Leslie Gunatilaka

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Scholarly Contributions

Chapters

• Gunatilaka, L. -. (2015). Bioprospecting Legumes of Arizona. In Legumes of Arizona: An Illustrated Flora and Reference (Ed. Kisten Lake).
• Gunatilaka, L., & Gunaherath, G. M. (2020). Plant Steroids: Occurrence, Biological Significance and their Analysis. In Handbook of Chemical and Biological Plant Analytical Methods - Updated Edition(pp 31 pages). Online Version: John Wiley & Sons, Ltd. doi:DOI: 10.1002/9780470027318.a9931.pub2
• Gunatilaka, L., Oliveira, M. C., & Mafezoli, J. (2017). Natural Products of the Rhizosphere and Its Microorganisms: Bioactivities and Implications of Occurrence. In Chemical Biology of Natural Products(pp 285-332). Boca Raton, Florida, USA: CRC Press, Taylor & Francis.
• Gunatilaka, L. -., & Gunaherath, G. (2014). Plant Steroids: Occurrence, Biological Significance and their Analysis. In Handbook of Chemical and Biological Plant Analytical Methods(pp 727-752). John Wiley & Sons.
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  Editor(s): Hostettmann, K

Journals/Publications

• Calderon-Rivera, A., Gomez, K., Loya-López, S., Wijeratne, E. M., Stratton, H., Tang, C., Duran, P., Masterson, K., Alsbiei, O., Gunatilaka, A. A., & Khanna, R. (2023). Betulinic acid analogs inhibit N- and T-type voltage-gated calcium channels to attenuate nerve-injury associated neuropathic and formalin models of pain. Neurobiology of pain (Cambridge, Mass.), 13, 100116.
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  Over the past three decades, there has been a significant growth in the use of natural products, with approximately 80% of individuals using them for some aspect of primary healthcare. Our laboratories have identified and studied natural compounds with analgesic effects from dry land plants or their associated fungus during the past ten years. Here, we isolated and characterized thirteen betulin analogs and fifteen betulinic acid analogs for their capacity to prevent calcium influx brought on by depolarization in sensory neurons. The in vitro inhibition of voltage-gated calcium channels by the top drugs was then assessed using whole cell patch clamp electrophysiology. In vivo experiments, conducted at two sites, evaluated the best compound in acute and tonic, neuropathic, inflammatory, post-operative and visceral models of pain. We found that the betulinic acid analog inhibited calcium influx in rat dorsal root ganglion neurons by inhibiting N- (CaV2.2) and T- (CaV3) type voltage-gated calcium channels. Moreover, intrathecal delivery of analog had analgesic activity in both spared nerve injury model of neuropathic pain and acute and tonic pain induced by formalin. The results presented herein highlight the potential antinociceptive properties of betulinic acid analog and set the stage for the development of novel non-opioid pain therapeutics based on the triterpenoid scaffold of betulinic acid.
• Zerio, C. J., Sivinski, J., Wijeratne, E. M., Xu, Y. M., Ngo, D. T., Ambrose, A. J., Villa-Celis, L., Ghadirian, N., Clarkson, M. W., Zhang, D. D., Horton, N. C., Gunatilaka, A. A., Fromme, R., & Chapman, E. (2023). Physachenolide C is a Potent, Selective BET Inhibitor. Journal of medicinal chemistry, 66(1), 913-933.
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  A pulldown using a biotinylated natural product of interest in the 17β-hydroxywithanolide (17-BHW) class, physachenolide C (PCC), identified the bromodomain and extra-terminal domain (BET) family of proteins (BRD2, BRD3, and BRD4), readers of acetyl-lysine modifications and regulators of gene transcription, as potential cellular targets. BROMOscan bromodomain profiling and biochemical assays support PCC as a BET inhibitor with increased selectivity for bromodomain (BD)-1 of BRD3 and BRD4, and X-ray crystallography and NMR studies uncovered specific contacts that underlie the potency and selectivity of PCC toward BRD3-BD1 over BRD3-BD2. PCC also displays characteristics of a molecular glue, facilitating proteasome-mediated degradation of BRD3 and BRD4. Finally, PCC is more potent than other withanolide analogues and gold-standard pan-BET inhibitor (+)-JQ1 in cytotoxicity assays across five prostate cancer (PC) cell lines regardless of androgen receptor (AR)-signaling status.
• Adams, A. C., Macy, A. M., Kang, P., Castro-Ochoa, K. F., Wijeratne, E. M., Xu, Y. M., Liu, M. X., Charos, A., Bosenberg, M. W., Gunatilaka, A. A., Sertil, A. R., & Hastings, K. T. (2022). Corrigendum to "Physachenolide C induces complete regression of established murine melanoma tumors via apoptosis and cell cycle arrest". Translational oncology, 21, 101446.
• Adams, A. C., Macy, A. M., Kang, P., Castro-Ochoa, K. F., Wijeratne, E. M., Xu, Y. M., Liu, M. X., Charos, A., Bosenberg, M. W., Gunatilaka, A. A., Sertil, A. R., & Hastings, K. T. (2022). Physachenolide C induces complete regression of established murine melanoma tumors via apoptosis and cell cycle arrest. Translational oncology, 15(1), 101259.
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  Melanoma is an aggressive skin cancer that metastasizes to other organs. While immune checkpoint blockade with anti-PD-1 has transformed the treatment of advanced melanoma, many melanoma patients fail to respond to anti-PD-1 therapy or develop acquired resistance. Thus, effective treatment of melanoma still represents an unmet clinical need. Our prior studies support the anti-cancer activity of the 17β-hydroxywithanolide class of natural products, including physachenolide C (PCC). As single agents, PCC and its semi-synthetic analog demonstrated direct cytotoxicity in a panel of murine melanoma cell lines, which share common driver mutations with human melanoma; the IC values ranged from 0.19-1.8 µM. PCC treatment induced apoptosis of tumor cells both in vitro and in vivo. In vivo treatment with PCC alone caused the complete regression of established melanoma tumors in all mice, with a durable response in 33% of mice after discontinuation of treatment. T cell-mediated immunity did not contribute to the therapeutic efficacy of PCC or prevent tumor recurrence in YUMM2.1 melanoma model. In addition to apoptosis, PCC treatment induced G0-G1 cell cycle arrest of melanoma cells, which upon removal of PCC, re-entered the cell cycle. PCC-induced cycle cell arrest likely contributed to the in vivo tumor recurrence in a portion of mice after discontinuation of treatment. Thus, 17β-hydroxywithanolides have the potential to improve the therapeutic outcome for patients with advanced melanoma.
• Duran, P., Loya-López, S., Ran, D., Tang, C., Calderon-Rivera, A., Gomez, K., Stratton, H. J., Huang, S., Xu, Y. M., Wijeratne, E. M., Perez-Miller, S., Shan, Z., Cai, S., Gabrielsen, A. T., Dorame, A., Masterson, K. A., Alsbiei, O., Madura, C. L., Luo, G., , Moutal, A., et al. (2022). The natural product argentatin C attenuates postoperative pain via inhibition of voltage-gated sodium and T-type voltage-gated calcium channels. British journal of pharmacology.
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  Postoperative pain occurs in as many as 70% of surgeries performed worldwide. Postoperative pain management still relies on opioids despite their negative consequences, resulting in a public health crisis. Therefore, it is important to develop alternative therapies to treat chronic pain. Natural products derived from medicinal plants are potential sources of novel biologically active compounds for development of safe analgesics. In this study, we screened a library of natural products to identify small molecules that target the activity of voltage-gated sodium and calcium channels that have important roles in nociceptive sensory processing.
• Gunatilaka, A. A., Inacio, M. C., Paz, T. A., Wijeratne, E. M., Gunaherath, G. B., & Guido, R. V. (2022). Antimicrobial activity of some celastrolids and their derivatives. Medicinal Chemistry Research, 1-13. doi:https://doi.org/10.1007/s00044-022-02927-6
• Gunatilaka, L., Madasu, C., Xu, Y., Liu, M. X., Wijeratne, E. M., & Molnar, I. (2022). Semi-synthesis and cytotoxicity evaluation of pyrimidine, thiazole, and indole analogues of argentatins A–C from guayule (Parthenium argentatum) resin. Medicinal Chemistry Research. doi:https://doi.org/10.1007/s00044-021-02835-1
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  Argentatins A–C (1–3), the major cycloartane-type triterpenoids of guayule resin, a byproduct of commercial rubber production, were converted into their pyrimidine (7–12), thiazole (13–15), and indole (16–18) analogues by a molecular hybridization approach. The cytotoxic activities of these fused heterocyclic analogues 7–18 were compared with those of argentatins A–C (1–3) against a panel of three sentinel human cancer cell lines [NCI-H460 (non-small cell lung), MCF-7 (breast adenocarcinoma), and SF-268 (central nervous system glioma)], and normal human fibroblast (WI-38) cells. The cytotoxicity data suggest that the pyrimidine analogues 7 and 8 (derived from 1), 9 and 10 (derived from 2), and 12 (derived from 3) had significantly enhanced activity compared to the parent compounds or their thiazole (13–15) and indole (16–18) analogues. These findings indicate that triterpenoid constituents of guayule resin may be exploited to obtain value-added products with potential applications in anticancer drug discovery.
• Xu, Y. M., Inacio, M. C., Liu, M. X., & Gunatilaka, A. A. (2022). Discovery of diminazene as a dual inhibitor of SARS-CoV-2 human host proteases TMPRSS2 and furin using cell-based assays. Current research in chemical biology, 2, 100023.
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  The proteases TMPRSS2 (transmembrane protease serine 2) and furin are known to play important roles in viral infectivity including systematic COVID-19 infection through priming of the spike protein of SARS-CoV-2 and related viruses. To discover small-molecules capable of inhibiting these host proteases, we established convenient and cost-effective cell-based assays employing Vero cells overexpressing TMPRSS2 and furin. A cell-based proteolytic assay for broad-spectrum protease inhibitors was also established using human prostate cancer cell line LNCaP. Evaluation of camostat, nafamostat, and gabexate in these cell-based assays confirmed their known TMPRSS2 inhibitory activities. Diminazene, a veterinary medicinal agent and a known furin inhibitor was found to inhibit both TMPRSS2 and furin with ICs of 1.35 and 13.2 M, respectively. Establishment and the use of cell-based assays for evaluation TMPRSS2 and furin inhibitory activity and implications of dual activity of diminazene vs TMPRSS2 and furin are presented.
• Xu, Y. M., Wijeratne, E. M., Liu, M. X., Xuan, L., Wang, W., & Gunatilaka, A. A. (2022). Production and Structural Diversification of Withanolides by Aeroponic Cultivation of Plants of Solanaceae: Cytotoxic and Other Withanolides from Aeroponically Grown Physalis coztomatl. Molecules (Basel, Switzerland), 27(3). doi:https://doi.org/10.3390/molecules27030909
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  Withanolides constitute one of the most interesting classes of natural products due to their diversity of structures and biological activities. Our recent studies on withanolides obtained from plants of Solanaceae including and a number of species grown under environmentally controlled aeroponic conditions suggested that this technique is a convenient, reproducible, and superior method for their production and structural diversification. Investigation of aeroponically grown afforded 29 withanolides compared to a total of 13 obtained previously from the wild-crafted plant and included 12 new withanolides, physacoztolides I-M (-), 15-acetoxy-28-hydroxyphysachenolide C (), 28-oxophysachenolide C (), and 28-hydroxyphysachenolide C (), 5-chloro-6-hydroxy-5,6-dihydrophysachenolide D (), 15-acetoxy-5-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (), 28-hydroxy-5-chloro-6-hydroxy-5,6-dihydrophysachenolide D (), physachenolide A-5-methyl ether (), and 17 known withanolides -, , and -. The structures of - were elucidated by the analysis of their spectroscopic data and the known withanolides -, , and - were identified by comparison of their spectroscopic data with those reported. Evaluation against a panel of prostate cancer (LNCaP, VCaP, DU-145, and PC-3) and renal carcinoma (ACHN) cell lines, and normal human foreskin fibroblast (WI-38) cells revealed that , , and - had potent and selective activity for prostate cancer cell lines. Facile conversion of the 5,6-chlorohydrin to its 5,6-epoxide in cell culture medium used for the bioassay suggested that the cytotoxic activities observed for - may be due to in situ formation of their corresponding 5β,6β-epoxides, , , and .
• Freitas Misakyan, M. F., Wijeratne, E. M., Issa, M. E., Xu, Y. M., Monteillier, A., Gunatilaka, A. A., & Cuendet, M. (2021). Structure-Activity Relationships of Withanolides as Antiproliferative Agents for Multiple Myeloma: Comparison of Activity in 2D Models and a 3D Coculture Model. Journal of natural products, 84(8), 2321-2335.
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  Multiple myeloma (MM) is a hematological cancer in which relapse and resistance are highly frequent. Therefore, alternatives to conventional treatments are necessary. Withaferin A, a withanolide isolated from , has previously shown promising activity against various MM models. In the present study, structure-activity relationships (SARs) were evaluated using 56 withanolides. The antiproliferative activity was assessed in three MM cell lines and in a 3D MM coculture model to understand the in vitro activity of compounds in models of various complexity. While the results obtained in 2D allowed a quick and simple evaluation of cytotoxicity used for a first selection, the use of the 3D MM coculture model allowed filtering compounds that perform better in a more complex setup. This study shows the importance of the last model as a bridge between 2D and in vivo studies to select the most active compounds and ultimately lead to a reduction of animal use for more sustained in vivo studies. NF-κB inhibition was determined to evaluate if this could be one of the targeted pathways. The most active compounds, withanolide D () and , should be further evaluated in vivo.
• Gunatilaka, L., Tewary, P., Brooks, A., Xu, Y., Wijeratne, K., Babyak, A., Back, T., Chari, R., Evans, C., Henrich, C., Meyer, T., & Sayers, T. (2021). A Small-Molecule Natural Product Potentiates Immunotherapy by Targeting BET Proteins, Reducing Levels of cFLIP and Promoting Caspase-8-Dependent Cancer Cell Death. Cancer Research, 81, 3374-3386. doi:10.1158/0008-5472.CAN-20-2634
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  Screening for sensitizers of cancer cells to TRAIL-mediated apoptosis identified a natural product (NP) of the 17β-hydroxywithanolide (17-BHW) class, physachenolide C (PCC), as a promising hit. In this study, we show that PCC was also able to sensitize melanoma and renal carcinoma cells to apoptosis in response not only to TRAIL, but also to the synthetic polynucleotide poly I:C, a viral mimetic and immune activator, by reducing levels of anti-apoptotic proteins cFLIP and Livin. Both death receptor and TLR3 signaling elicited subsequent increased assembly of a pro-apoptotic ripoptosome signaling complex. Administration of a combination of PCC and poly I:C in human M14 melanoma xenograft and a syngeneic B16 melanoma model provided significant therapeutic benefit as compared to individual agents. Additionally, PCC enhanced melanoma cell death in response to activated human T cells in vitro and in vivo in a death ligand-dependent manner. Biochemical mechanism of action studies established bromo and extraterminal domain (BET) proteins as major cellular targets of PCC. Thus, by targeting of BET proteins to reduce anti-apoptotic proteins and enhance caspase 8-dependent apoptosis of cancer cells, PCC represents a unique agent that can potentially be used in combination with various immunotherapeutic approaches to promote tumor regression and improve outcome.
• Gunatilaka, L., Xu, G., Xu, Y., Wijeratne, K., Ranjbar, F., & Liu, M. (2021). Cytotoxic Physalins from Aeroponically Grown Physalis acutifolia. Journal of Natural Products.
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  Aeroponically grown Physalis acutifolia afforded five new and six known withanolides including ten physalins. The structures of the new withanolides, acutifolactone (1), 5β,6β-epoxyphysalin C (2), 5α-chloro-6β-hydroxyphysalin C (3), and an inseparable mixture of 5β,6β-epoxy-2,3-dihydrophysalin F-3β-O-sulfate (4) and 5β,6β-epoxy-2,3-dihydrophysalin C-3β-O-sulfate (5) were elucidated by extensive analysis of their spectroscopic data and chemical interconversions. The known withanolides were identified as physalins B (6), D (7), F (8), H (9), I (10), and U (11) by comparison of their spectroscopic data with those reported. Evaluation of 1–11 and the derivatives, 12 and 12a, obtained from 4 and 5 against a panel of four human cancer cell lines [NCI-H460 (non-small cell lung), SF-268 (CNS glioma), PC-3 (prostate adenocarcinoma) and MCF-7 (breast adenocarcinoma)] and normal human fibroblast (WI-38) cells revealed that physalins 2, 3, 8, and 9 exhibited selective cytotoxic activity to at least one of the cancer cell lines tested compared to the normal cells and that 7, 10, and 11 were inactive up to a concentration of 5.0 microM. These data provided some preliminary structure-activity relationships and suggested that the mechanism of cytotoxic activity of physalins may differ from other classes of withanolides.
• Gunatilaka, L., Xu, Y., Madasu, C., Liu, M. X., Wijeratne, E. K., Dierig, D., White, B., & Molnar, I. (2021). Cycloartane and Lanostane Type Triterpenoids from the Resin of Parthenium argentatum AZ-2, A Byproduct of Guayule Rubber Production. ACS Omega, 6, 154486-154498. doi:doi.org/10.1021/acsomega.1c01714
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  Twelve new cycloartane and lanostane type triterpenoids including 16-deoxyargentatin A (1), 16-deoxyisoargentatin A (2), 7-oxoisoargentatin A (3), 24-epi-argentatin H (4), 24-O-p-anisoylargentatin C (5), 24-O-trans-cinnamoylargentatin C (6), 16-dehydroargentatin C (7), 16,17(20)-didehydroargentatin C (8), isoargentatin C (9), isoargentatin H (10), 3-epi-quisquagenin (11), and isoquisquagenin (12) together with ten known triterpenoids (13−22), were isolated from the resin of Parthenium argentatum AZ-2 obtained as a byproduct of Bridgestone guayule rubber production. The structures of new triterpenoids 1−12 and argentatin H (13), which has previously been characterized as it’s diacetate (23), were elucidated by extensive analysis of their spectroscopic data and chemical conversions, and the known compounds 14−22 were identified by comparison of their spectroscopic data with those reported. Of these, 13, 14 and 18 exhibited weak cytotoxic activity for several cancer cell lines.
• Kithsiri Wijeratne, E. M., Xu, Y. M., Liu, M. X., Inacio, M. C., Brooks, A. D., Tewary, P., Sayers, T. J., & Gunatilaka, A. A. (2021). Ring A/B-Modified 17β-Hydroxywithanolide Analogues as Antiproliferative Agents for Prostate Cancer and Potentiators of Immunotherapy for Renal Carcinoma and Melanoma. Journal of natural products, 84(12), 3029-3038.
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  Physachenolide C () is a 17β-hydroxywithanolide natural product with a unique anticancer potential, as it exhibits potent and selective in vitro antiproliferative activity against prostate cancer (PC) cells and promotes TRAIL-induced apoptosis of renal carcinoma (RC) and poly I:C-induced apoptosis of melanoma cells. To explore the effect of ring A/B modifications of physachenolide C () on these biological activities, 23 of its natural and semisynthetic analogues were evaluated. Analogues - were prepared by chemical transformations of a readily accessible compound, physachenolide D (). Compound and its analogues - were evaluated for their antiproliferative activity against PC (LNCaP and 22Rv1), RC (ACHN), and melanoma (M14 and SK-MEL-28) cell lines and normal human foreskin fibroblast (HFF) cells. Most of the active analogues had selective and potent activity in reducing cell number for PC cell lines, some showing selectivity for androgen-independent and enzalutamide-resistant 22Rv1 cells compared to androgen-dependent LNCaP cells. Analogues with ICs below 5.0 μM against ACHN cells, when tested in the presence of TRAIL, showed a significantly increased ability to reduce cell number, and those analogues active against the M14 and SK-MEL-28 cell lines exhibited enhanced activity when combined with poly I:C. These data provide additional structure-activity relationship information for 17β-hydroxywithanolides and suggest that selective activities of some analogues may be exploited to develop natural products-based tumor-specific agents for cancer chemotherapy.
• Lacombe, J., Cretignier, T., Meli, L., Wijeratne, E. M., Veuthey, J. L., Cuendet, M., Gunatilaka, A. A., & Zenhausern, F. (2021). Withanolide D Enhances Radiosensitivity of Human Cancer Cells by Inhibiting DNA Damage Non-homologous End Joining Repair Pathway. Frontiers in oncology. doi:doi.org/10.3389/fonc.2019.01468
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  Along with surgery and chemotherapy, radiation therapy (RT) is an important modality in cancer treatment, and the development of radiosensitizers is a current key challenge in radiobiology to maximize RT efficiency. In this study, the radiosensitizing effect of a natural compound from the withanolide family, withanolide D (WD), was assessed. Clonogenic assays showed that a 1 h WD pretreatment (0.7 μM) before irradiation decreased the surviving fraction of several cancer cell lines. To determine the mechanisms by which WD achieved its radiosensitizing effect, we then assessed whether WD could promote radiation-induced DNA damages and inhibit double-strand breaks (DSBs) repair in SKOV3 cells. Comet and γH2AX/53BP1 foci formation assays confirmed that DSBs were higher between 1 and 24 h after 2 Gy-irradiation in WD-treated cells compared to vehicle-treated cells, suggesting that WD induced the persistence of radiation-induced DNA damages. Immunoblotting was then performed to investigate protein expression involved in DNA repair pathways. Interestingly, DNA-PKc, ATM, and their phosphorylated forms appeared to be inhibited 24 h post-irradiation in WD-treated samples. XRCC4 expression was also down-regulated while RAD51 expression did not change compared to vehicle-treated cells suggesting that only non-homologous end joining (NHEJ) pathways was inhibited by WD. Mitotic catastrophe (MC) was then investigated in SKOV3, a p53-deficient cell line, to assess the consequence of such inhibition. MC was induced after irradiation and was predominant in WD-treated samples as shown by the few numbers of cells pursuing into anaphase and the increased amount of bipolar metaphasic cells. Together, these data demonstrated that WD could be a promising radiosensitizer candidate for RT by inhibiting NHEJ pathway and promoting MC. Additional studies are required to better understand its efficiency and mechanism of action in more relevant clinical models.
• Tewary, P., Brooks, A. D., Xu, Y. M., Wijeratne, E. M., Babyak, A. L., Back, T. C., Chari, R., Evans, C. N., Henrich, C. J., Meyer, T. J., Edmondson, E. F., de Aquino, M. T., Kanagasabai, T., Shanker, A., Gunatilaka, A. A., & Sayers, T. J. (2021). Small-Molecule Natural Product Physachenolide C Potentiates Immunotherapy Efficacy by Targeting BET Proteins. Cancer research, 81(12), 3374-3386.
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  Screening for sensitizers of cancer cells to TRAIL-mediated apoptosis identified a natural product of the 17β-hydroxywithanolide (17-BHW) class, physachenolide C (PCC), as a promising hit. In this study, we show that PCC was also able to sensitize melanoma and renal carcinoma cells to apoptosis in response not only to TRAIL, but also to the synthetic polynucleotide poly I:C, a viral mimetic and immune activator, by reducing levels of antiapoptotic proteins cFLIP and Livin. Both death receptor and TLR3 signaling elicited subsequent increased assembly of a proapoptotic ripoptosome signaling complex. Administration of a combination of PCC and poly I:C in human M14 melanoma xenograft and a syngeneic B16 melanoma model provided significant therapeutic benefit as compared with individual agents. In addition, PCC enhanced melanoma cell death in response to activated human T cells and in a death ligand-dependent manner. Biochemical mechanism-of-action studies established bromo and extraterminal domain (BET) proteins as major cellular targets of PCC. Thus, by targeting of BET proteins to reduce antiapoptotic proteins and enhance caspase-8-dependent apoptosis of cancer cells, PCC represents a unique agent that can potentially be used in combination with various immunotherapeutic approaches to promote tumor regression and improve outcome. SIGNIFICANCE: These findings demonstrate that PCC selectively sensitizes cancer cells to immune-mediated cell death, potentially improving the efficacy of cancer immunotherapies. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/12/3374/F1.large.jpg.
• Xu, G. B., Xu, Y. M., Wijeratne, E. M., Ranjbar, F., Liu, M. X., & Gunatilaka, A. A. (2021). Cytotoxic Physalins from Aeroponically Grown. Journal of natural products, 84(2), 187-194.
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  Aeroponically grown afforded five new and six known withanolides including 10 physalins. The structures of the new withanolides, acutifolactone (), 5β,6β-epoxyphysalin C (), 5α-chloro-6β-hydroxyphysalin C (), and an inseparable mixture of 5β,6β-epoxy-2,3-dihydrophysalin F-3β--sulfate () and 5β,6β-epoxy-2,3-dihydrophysalin C-3β--sulfate (), were elucidated by analysis of their spectroscopic data and chemical interconversions. The known withanolides were identified as physalins B (), D (), F (), H (), I (), and U () by comparison of their spectroscopic data with those reported. Evaluation of - and the derivatives, and , obtained from and against a panel of four human cancer cell lines [NCI-H460 (non-small-cell lung), SF-268 (CNS glioma), PC-3 (prostate adenocarcinoma), and MCF-7 (breast adenocarcinoma)] and normal human lung fibroblast (WI-38) cells revealed that physalins , , , and exhibited selective cytotoxic activity to at least one of the cancer cell lines tested compared to the normal cells and that , , and were inactive up to a concentration of 10.0 μM. These data provided some preliminary structure-activity relationships and suggested that the mechanism of cytotoxic activity of physalins may differ from other classes of withanolides.
• Xu, Y. M., Madasu, C., Liu, M. X., Wijeratne, E. M., Dierig, D., White, B., Molnár, I., & Gunatilaka, A. A. (2021). Cycloartane- and Lanostane-Type Triterpenoids from the Resin of AZ-2, a Byproduct of Guayule Rubber Production. ACS omega, 6(23), 15486-15498.
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  A total of 12 new cycloartane- and lanostane-type triterpenoids including 16-deoxyargentatin A (), 16-deoxyisoargentatin A (), 7-oxoisoargentatin A (), 24--argentatin H (), 24---anisoylargentatin C (), 24---cinnamoylargentatin C (), 16-dehydroargentatin C (), 16,17(20)-didehydroargentatin C (), isoargentatin C (), isoargentatin H (), 3--quisquagenin (), and isoquisquagenin () together with 10 known triterpenoids (-) were isolated from the resin of AZ-2 obtained as a byproduct of Bridgestone guayule rubber production. The structures of new triterpenoids - and argentatin H (), which has previously been characterized as its diacetate (), were elucidated by extensive analysis of their spectroscopic data and chemical conversions, and the known compounds - were identified by comparison of their spectroscopic data with those reported. Of these, , , and exhibited weak cytotoxic activity for several cancer cell lines.
• Wang, C., Wang, X., Zhang, L., Yue, Q., Liu, Q., Xu, Y. M., Gunatilaka, A. A., Wei, X., Xu, Y., & Molnár, I. (2020). Intrinsic and Extrinsic Programming of Product Chain Length and Release Mode in Fungal Collaborating Iterative Polyketide Synthases. Journal of the American Chemical Society, 142(40), 17093-17104.
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  Combinatorial biosynthesis with fungal polyketide synthases (PKSs) promises to produce unprecedented bioactive "unnatural" natural products (uNPs) for drug discovery. Genome mining of the dothideomycete uncovered a collaborating highly reducing PKS (hrPKS)-nonreducing PKS (nrPKS) pair. These enzymes produce trace amounts of rare S-type benzenediol macrolactone congeners with a phenylacetate core in a heterologous host. However, subunit shuffling and domain swaps with voucher enzymes demonstrated that all PKS domains are highly productive. This contradiction led us to reveal novel programming layers exerted by the starter unit acyltransferase (SAT) and the thioesterase (TE) domains on the PKS system. First, macrocyclic vs linear product formation is dictated by the intrinsic biosynthetic program of the TE domain. Next, the chain length of the hrPKS product is strongly influenced by the off-loading preferences of the nrPKS SAT domain. Last, TE domains are size-selective filters that facilitate or obstruct product formation from certain priming units. Thus, the intrinsic programs of the SAT and TE domains are both part of the extrinsic program of the hrPKS subunit and modulate the observable metaprogram of the whole PKS system. Reconstruction of SAT and TE phylogenies suggests that these domains travel different evolutionary trajectories, with the resulting divergence creating potential conflicts in the PKS metaprogram. Such conflicts often emerge in chimeric PKSs created by combinatorial biosynthesis, reducing biosynthetic efficiency or even incapacitating the system. Understanding the points of failure for such engineered biocatalysts is pivotal to advance the biosynthetic production of uNPs.
• Xu, Y. M., Arnold, A. E., U Ren, J. M., Xuan, L. J., Wang, W. Q., & Gunatilaka, A. A. (2020). Teratopyrones A-C, Dimeric Naphtho-γ-Pyrones and Other Metabolites from sp. AK1128, a Fungal Endophyte of. Molecules (Basel, Switzerland), 25(21).
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  Bioassay-guided fractionation of a cytotoxic extract derived from a solid potato dextrose agar (PDA) culture of sp. AK1128, a fungal endophyte of , afforded three new naphtho-γ-pyrone dimers, teratopyrones A-C (-), together with five known naphtho-γ-pyrones, aurasperone B (), aurasperone C (), aurasperone F (), nigerasperone A (), and fonsecin B (), and two known diketopiperazines, asperazine () and isorugulosuvine (). The structures of - were determined on the basis of their spectroscopic data. Cytotoxicity assay revealed that nigerasperone A () was moderately active against the cancer cell lines PC-3M (human metastatic prostate cancer), NCI-H460 (human non-small cell lung cancer), SF-268 (human CNS glioma), and MCF-7 (human breast cancer), with ICs ranging from 2.37 to 4.12 μM while other metabolites exhibited no cytotoxic activity up to a concentration of 5.0 μM.
• Zhou, Y., Cai, S., Gomez, K., Wijeratne, E. M., Ji, Y., Bellampalli, S. S., Luo, S., Moutal, A., Gunatilaka, A. A., & Khanna, R. (2020). 1-O-Acetylgeopyxin A, a derivative of a fungal metabolite, blocks tetrodotoxin-sensitive voltage-gated sodium, calcium channels and neuronal excitability which correlates with inhibition of neuropathic pain. Molecular brain, 13(1), 73.
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  Chronic pain can be the result of an underlying disease or condition, medical treatment, inflammation, or injury. The number of persons experiencing this type of pain is substantial, affecting upwards of 50 million adults in the United States. Pharmacotherapy of most of the severe chronic pain patients includes drugs such as gabapentinoids, re-uptake blockers and opioids. Unfortunately, gabapentinoids are not effective in up to two-thirds of this population and although opioids can be initially effective, their long-term use is associated with multiple side effects. Therefore, there is a great need to develop novel non-opioid alternative therapies to relieve chronic pain. For this purpose, we screened a small library of natural products and their derivatives in the search for pharmacological inhibitors of voltage-gated calcium and sodium channels, which are outstanding molecular targets due to their important roles in nociceptive pathways. We discovered that the acetylated derivative of the ent-kaurane diterpenoid, geopyxin A, 1-O-acetylgeopyxin A, blocks voltage-gated calcium and tetrodotoxin-sensitive voltage-gated sodium channels but not tetrodotoxin-resistant sodium channels in dorsal root ganglion (DRG) neurons. Consistent with inhibition of voltage-gated sodium and calcium channels, 1-O-acetylgeopyxin A reduced reduce action potential firing frequency and increased firing threshold (rheobase) in DRG neurons. Finally, we identified the potential of 1-O-acetylgeopyxin A to reverse mechanical allodynia in a preclinical rat model of HIV-induced sensory neuropathy. Dual targeting of both sodium and calcium channels may permit block of nociceptor excitability and of release of pro-nociceptive transmitters. Future studies will harness the core structure of geopyxins for the generation of antinociceptive drugs.
• de Amorim, M. R., Wijeratne, E. M., Zhou, S., Arnold, A. E., Batista, A. N., Batista, J. M., Dos Santos, L. C., & Gunatilaka, A. A. (2020). An epigenetic modifier induces production of 3-(4-oxopyrano)-chromen-2-ones in sp. AST0006, an endophytic fungus of. Tetrahedron, 76(43).
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  Incorporation of the epigenetic modifier suberoylanilide hydroxamic acid (SAHA) into a potato dextrose broth culture of the endophytic fungus sp. AST0006 affected its polyketide biosynthetic pathway providing two new 3-(4-oxopyrano)-chromen-2-ones, aspyranochromenones A () and B (), and the isocoumarin, (-)-6,7-dihydroxymellein (). Eight additional metabolites (-) and two biotransformation products of SAHA (-) were also encountered. The planar structures and relative configurations of the new metabolites - were elucidated with the help of high-resolution mass, 1D and 2D NMR spectroscopic data and the absolute configurations of - were determined by comparison of experimental and calculated ECD data. Possible biosynthetic pathways to and are presented.
• Bellampalli, S. S., Ji, Y., Moutal, A., Cai, S., Wijeratne, E. M., Gandini, M. A., Yu, J., Chefdeville, A., Dorame, A., Chew, L. A., Madura, C. L., Luo, S., Molnar, G., Khanna, M., Streicher, J. M., Zamponi, G. W., Gunatilaka, A. A., & Khanna, R. (2019). Betulinic acid, derived from the desert lavender Hyptis emoryi, attenuates paclitaxel-, HIV-, and nerve injury-associated peripheral sensory neuropathy via block of N- and T-type calcium channels. Pain, 160(1), 117-135.
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  The Federal Pain Research Strategy recommended development of nonopioid analgesics as a top priority in its strategic plan to address the significant public health crisis and individual burden of chronic pain faced by >100 million Americans. Motivated by this challenge, a natural product extracts library was screened and identified a plant extract that targets activity of voltage-gated calcium channels. This profile is of interest as a potential treatment for neuropathic pain. The active extract derived from the desert lavender plant native to southwestern United States, when subjected to bioassay-guided fractionation, afforded 3 compounds identified as pentacyclic triterpenoids, betulinic acid (BA), oleanolic acid, and ursolic acid. Betulinic acid inhibited depolarization-evoked calcium influx in dorsal root ganglion (DRG) neurons predominantly through targeting low-voltage-gated (Cav3 or T-type) and CaV2.2 (N-type) calcium channels. Voltage-clamp electrophysiology experiments revealed a reduction of Ca, but not Na, currents in sensory neurons after BA exposure. Betulinic acid inhibited spontaneous excitatory postsynaptic currents and depolarization-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices. Notably, BA did not engage human mu, delta, or kappa opioid receptors. Intrathecal administration of BA reversed mechanical allodynia in rat models of chemotherapy-induced peripheral neuropathy and HIV-associated peripheral sensory neuropathy as well as a mouse model of partial sciatic nerve ligation without effects on locomotion. The broad-spectrum biological and medicinal properties reported, including anti-HIV and anticancer activities of BA and its derivatives, position this plant-derived small molecule natural product as a potential nonopioid therapy for management of chronic pain.
• Cai, S., Bellampalli, S. S., Yu, J., Li, W., Ji, Y., Wijeratne, E. M., Dorame, A., Luo, S., Shan, Z., Khanna, M., Moutal, A., Streicher, J. M., Gunatilaka, A. A., & Khanna, R. (2018). (-)-Hardwickiic acid and Hautriwaic acid induce antinociception via blockade of tetrodotoxin-sensitive voltage-dependent sodium channels. ACS chemical neuroscience, 20(10), 1716-1728. doi:doi: 10.1021/acschemneuro.8b00617
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  For an affliction that debilitates an estimated 50 million of U.S. adults, the current chronic pain management approaches are inadequate. The Centers for Disease Control and Prevention have called for a minimization in opioid prescription and use for chronic pain conditions, and thus, it is imperative to discover alternative non-opioid based strategies. For the realization of this call, a library of natural products was screened in search of pharmacological inhibitors of both voltage-gated calcium channels and voltage-gated sodium channels, excellent targets due to their well-established roles in nociceptive pathways. We discovered (-)-hardwickiic acid ((-)-HDA) and hautriwaic acid (HTA) isolated from plants, Croton californicus and Eremocarpus setigerus, respectively, inhibited tetrodotoxin-sensitive sodium, but not calcium or potassium, channels in small diameter, presumptively nociceptive, dorsal root ganglion (DRG) neurons. Failure to inhibit spontaneous post-synaptic excitatory currents indicated a preferential targeting of voltage-gated sodium channels over voltage-gated calcium channels by these extracts. Neither compound was a ligand at opioid receptors. Finally, we identified the potential of both (-)-HDA and HTA to reverse chronic pain behavior in preclinical rat models of HIV-sensory neuropathy, and for (-)-HDA specifically, in chemotherapy-induced peripheral neuropathy. Our results illustrate the therapeutic potential for (-)-HDA and HTA for chronic pain management and could represent a scaffold, that, if optimized by structure-activity relationship studies, may yield novel specific sodium channel antagonists for pain relief.
• Gunatilaka, L., & Molnar, I. (2018). Rational reprogramming O-methylation regioselectivity for combinatorial biosynthetic tailoring of benzenediol lactone scaffolds. Journal of the American Chemical Society.
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  O-Methylation modulates the pharmacokinetic and pharmacodynamic (PK/PD) properties of small molecule natural products affecting their bioavailability, stability, and binding to targets. Diversity-oriented combinatorial biosynthesis of new chemical entities for drug discovery, and optimization of known bioactive scaffolds during drug development both demand efficient O-methyltransferase (OMT) biocatalysts with considerable substrate promiscuity and tunable regioselectivity that can be deployed in a scalable and sustainable manner. Here we demonstrate efficient total biosynthetic and biocatalytic platforms that use a pair of fungal OMTs with orthogonal regiospecificity to produce unnatural O-methylated benzenediol lactone (BDL) polyketides. We show that rational, structure-guided active site cavity engineering can reprogram the regioselectivity of these enzymes. We also characterize the interplay of engineered regioselectivity with substrate plasticity. These findings will guide combinatorial biosynthetic tailoring of unnatural products towards the generation of diverse chemical matter for drug discovery and the PK/PD optimization of bioactive scaffolds for drug development.
• Gunatilaka, L., Chapman, E., Zhang, D. D., Wijeratne, E. M., Tao, S., Tian, W., & Tillotson, J. (2018). NRF2 Activation by Geopyxins Protects Cells from Toxicants. Cell Chemical Biology.
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  Under normal conditions, NRF2 levels are low due to the action of the ubiquitin proteasome system, where KEAP1 functions as the specificity factor of a CUL3-containing E3 ubiquitin ligase. KEAP1 has an active cysteine, C151, that acts as a sensor. When C151 is modified by electrophiles or oxidants, NRF2 is protected from degradation and can transcribe cellular protective genes. All known therapeutic NRF2 inducers are electrophilic molecules. However, due of the promiscuous nature of these reactive compounds, electrophilic NRF2 inducers have many unwanted off-target effects, resulting in toxicity and off target liabilities. During our studies to discover natural products-based modulators of the NRF2 pathway, we have encountered a group of ent-kaurane diterpenoids, geopyxins, with promising activity. We were particularly interested in comparing biological activities of structurally-related small molecule NRF2 inducers with and without C151 reactive electrophilic moieties. We now report a detailed investigation of 16 geopyxins and the detailed evaluation of geopyxin F as a C151 independent activator of the NRF2 pathway. Interestingly, geopyxin F showed enhanced cellular protection relative to canonical, electrophilic NRF2 activators. To our knowledge, this represents the first detailed structure activity relationship study of covalent versus non-covalent NRF2 activators, showing the promise of non-covalent NRF2 activators as potential therapeutic compounds.
• Shan, Z., Cai, S., Yu, J., Zhang, Z., Vallecillo, T. G., Serafini, M. J., Thomas, A. M., Pham, N. Y., Bellampalli, S. S., Moutal, A., Zhou, Y., Xu, G. B., Xu, Y. M., Luo, S., Patek, M., Streicher, J. M., Gunatilaka, A. A., & Khanna, R. (2019). Reversal of Peripheral Neuropathic Pain by the Small-Molecule Natural Product Physalin F via Block of CaV2.3 (R-Type) and CaV2.2 (N-Type) Voltage-Gated Calcium Channels. ACS chemical neuroscience, 10(6), 2939-2955.
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  No universally efficacious therapy exists for chronic pain, a disease affecting one-fifth of the global population. An overreliance on the prescription of opioids for chronic pain despite their poor ability to improve function has led to a national opioid crisis. In 2018, the NIH launched a Helping to End Addiction Long-term plan to spur discovery and validation of novel targets and mechanisms to develop alternative nonaddictive treatment options. Phytochemicals with medicinal properties have long been used for various treatments worldwide. The natural product physalin F, isolated from the Physalis acutifolia (family: Solanaceae) herb, demonstrated antinociceptive effects in models of inflammatory pain, consistent with earlier reports of its anti-inflammatory and immunomodulatory activities. However, the target of action of physalin F remained unknown. Here, using whole-cell and slice electrophysiology, competition binding assays, and experimental models of neuropathic pain, we uncovered a molecular target for physalin F's antinociceptive actions. We found that physalin F (i) blocks CaV2.3 (R-type) and CaV2.2 (N-type) voltage-gated calcium channels in dorsal root ganglion (DRG) neurons, (ii) does not affect CaV3 (T-type) voltage-gated calcium channels or voltage-gated sodium or potassium channels, (iii) does not bind G-protein coupled opioid receptors, (iv) inhibits the frequency of spontaneous excitatory postsynaptic currents (EPSCs) in spinal cord slices, and (v) reverses tactile hypersensitivity in models of paclitaxel-induced peripheral neuropathy and spinal nerve ligation. Identifying CaV2.2 as a molecular target of physalin F may spur its use as a tool for mechanistic studies and position it as a structural template for future synthetic compounds.
• Shi, T., Wijeratne, E. M., Solano, C., Ambrose, A. J., Ross, A. B., Norwood, C., Orido, C. K., Grigoryan, T., Tillotson, J., Kang, M., Luo, G., Keegan, B. M., Hu, W., Blagg, B. S., Zhang, D. D., Gunatilaka, A. A., & Chapman, E. (2019). An Isoform-Selective PTP1B Inhibitor Derived from Nitrogen-Atom Augmentation of Radicicol. Biochemistry, 58(30), 3225-3231.
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  A library of natural products and their derivatives was screened for inhibition of protein tyrosine phosphatase (PTP) 1B, which is a validated drug target for the treatment of obesity and type II diabetes. Of those active in the preliminary assay, the most promising was compound containing a novel pyrrolopyrazoloisoquinolone scaffold derived by treating radicicol () with hydrazine. This nitrogen-atom augmented radicicol derivative was found to be PTP1B selective relative to other highly homologous nonreceptor PTPs. Biochemical evaluation, molecular docking, and mutagenesis revealed to be an allosteric inhibitor of PTP1B with a submicromolar . Cellular analyses using C2C12 myoblasts indicated that restored insulin signaling and increased glucose uptake.
• Wang, X., Wang, C., Duan, L., Zhang, L., Liu, H., Xu, Y., Liu, Q., Mao, T., Zhang, W., Chen, M., Lin, M., Gunatilaka, L., Xu, Y., & Molnar, I. (2019). Rational reprogramming O-methylation regioselectivity for combinatorial biosynthetic tailoring of benzenediol lactone scaffolds. Journal of the American Chemical Society, 141, 4355-4364. doi:DOI: 10.1021/jacs.8b12967
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  O-Methylation modulates the pharmacokinetic and pharmacodynamic (PK/PD) properties of small-molecule natural products, affecting their bioavailability, stability, and binding to targets. Diversity-oriented combinatorial biosynthesis of new chemical entities for drug discovery and optimization of known bioactive scaffolds during drug development both demand efficient O-methyltransferase (OMT) biocatalysts with considerable substrate promiscuity and tunable regioselectivity that can be deployed in a scalable and sustainable manner. Here we demonstrate efficient total biosynthetic and biocatalytic platforms that use a pair of fungal OMTs with orthogonal regiospecificity to produce unnatural O-methylated benzenediol lactone polyketides. We show that rational, structure-guided active-site cavity engineering can reprogram the regioselectivity of these enzymes. We also characterize the interplay of engineered regioselectivity with substrate plasticity. These findings will guide combinatorial biosynthetic tailoring of unnatural products toward the generation of diverse chemical matter for drug discovery and the PK/PD optimization of bioactive scaffolds for drug development.
• Gunatilaka, L., Mafezoli, J., Xu, Y., Freidhof, B., Hilário, F., Espinosa-Artiles, P., Santos, L. d., & Oliveira, M. d. (2018). Modulation of polyketide biosynthetic pathway of the endophytic fungus, Anteaglonium sp. FL0768, by copper (II) and anacardic acid. Phytochemistry Letters, 28, 157-163.
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  In an attempt to explore the biosynthetic potential of endosymbiotic fungi, the secondary metabolite profiles of the endophytic fungus, Anteaglonium sp. FL0768, cultured under a variety of conditions were investigated. Inpotato dextrose broth (PDB) medium, Anteaglonium sp. FL0768 produced the heptaketides, herbaridine A (1), herbarin (2), 1-hydroxydehydroherbarin (3), scorpinone (4), and the methylated hexaketide 9S,11R-(+)ascosalitoxin(5). Incorporation of commonly used epigenetic modifiers, 5-azacytidine and suberoylanilide hydroxamicacid, into the PDB culture medium of this fungus had no effect on its secondary metabolite profile.However, the histone acetyl transferase inhibitor, anacardic acid, slightly affected the metabolite profile affording scorpinone (4) as the major metabolite together with 1-hydroxydehydroherbarin (3) and a differentmethylated hexaketide, ascochitine (6). Intriguingly, incorporaion of Cu2+ into the PDB medium enhanced production of metabolites and drastically affected the biosynthetic pathway resulting in the production ofpentaketide dimers, palmarumycin CE4 (7), palmarumycin CP4 (8), and palmarumycin CP1 (9), in addition to ascochitine (6). The structure of the new metabolite 7 was established with the help of spectroscopic data and by MnO2 oxidation to the known pentaketide dimer, palmarumycin CP3 (10). Biosynthetic pathways to some metabolites in Anteaglonium sp. FL0768 are presented and possible effects of AA and Cu2+ on these pathways arediscussed
• Padumadasa, C., Xu, Y., Wijeratne, K., U'Ren, J., Arnold, E., & Gunatilaka, L. (2018). Cytotoxic and Non-Cytotoxic Metabolites from Teratosphaeria sp. FL2137, a Fungus Associated with Pinus clausa. Journal of Natural Products, 81, 616-624. doi:10.1021/acs.jnatprod.7b00838
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  A new naphthoquinone, teratosphaerone A (1), four new naphthalenones, namely, teratosphaerone B (2),structurally related to 1, iso-balticol B (3), iso-balticol B-4,9-acetonide (4), and (+)-balticol C (5), a new furanonaphthalenone,(3aS,9R,9aS)-1(9a),3(3a),9-hexahydromonosporascone (6), and the known metabolite monosporascone (7) were isolated fromTeratosphaeria sp. FL2137, a fungal strain inhabiting the internal tissue of recently dead but undecomposed foliage of Pinus clausa. The structures of 1−6 were elucidated on the basis of their spectroscopic data including 2D NMR, and absolute configurations of 2, 3, and 6 were determined by the modified Mosher’s ester method. When evaluated in a panel of five tumor cell lines, metabolites 1 and 7 isolated from a cytotoxic fraction of the extract exhibited moderate selectivity for metastatic breastadenocarcinoma cell line MDA-MB-231. Of these, 1 showed cytotoxicity to this cell line with an IC50 of 1.2 ± 0.1 μM.
• Wijeratne, K., Oliviera, M., Mafazoli, J., Xu, Y., Minguzzi, S., Batista, P., Pessoa, O., Whitesell, L., & Gunatilaka, L. (2018). Withaferin A and Withanolide D Analogues with Dual Heat-Shock-Inducing and Cytotoxic Activities: Semisynthesis and Biological Evaluation. Journal of Natural Products, 81, 825-837.
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  To understand the relationship between the structure and the remarkably diverse bioactivities reported for withanolides, we obtained withaferin A (WA; 1) and 36 analogues (2−37) and compared their cytotoxicity tocytoprotective heat-shock-inducing activity (HSA). By analyzingstructure−activity relationships for the series, we found that the ring A enone is essential for both bioactivities. Acetylation of 27-OH of 4-epi-WA (28) to 33 enhanced both activities, whereas introduction of β-OH to WA at C-12 (29) and C-15 (30) decreased both activities. Introduction of β-OAc to 4,27-diacetyl-WA (16) at C-15 (37) decreased HSA without affecting cytotoxicity, but at C-12 (36), it had minimal effect. Importantly, acetylation of 27-OH, yielding 15 from 1, 16 from 14, and 35 from 34, enhanced HSA without increasing cytotoxicity. Our findings demonstrate that the withanolide scaffold can be modified to enhance HSA selectively, thereby assisting development of natural product-inspired drugs to combat proteinaggregation-associated diseases by stimulating cellular defense mechanisms.
• Xie, L., Zhang, L., Wang, C., Wang, X., Xu, Y. M., Yu, H., Wu, P., Li, S., Han, L., Gunatilaka, A. A., Wei, X., Lin, M., Molnár, I., & Xu, Y. (2018). Methylglucosylation of aromatic amino and phenolic moieties of drug-like biosynthons by combinatorial biosynthesis. Proceedings of the National Academy of Sciences of the United States of America, 115(22), E4980-E4989.
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  Glycosylation is a prominent strategy to optimize the pharmacokinetic and pharmacodynamic properties of drug-like small-molecule scaffolds by modulating their solubility, stability, bioavailability, and bioactivity. Glycosyltransferases applicable for "sugarcoating" various small-molecule acceptors have been isolated and characterized from plants and bacteria, but remained cryptic from filamentous fungi until recently, despite the frequent use of some fungi for whole-cell biocatalytic glycosylations. Here, we use bioinformatic and genomic tools combined with heterologous expression to identify a glycosyltransferase-methyltransferase (GT-MT) gene pair that encodes a methylglucosylation functional module in the ascomycetous fungus The GT is the founding member of a family nonorthologous to characterized fungal enzymes. Using combinatorial biosynthetic and biocatalytic platforms, we reveal that this GT is a promiscuous enzyme that efficiently modifies a broad range of drug-like substrates, including polyketides, anthraquinones, flavonoids, and naphthalenes. It yields both - and -glucosides with remarkable regio- and stereospecificity, a spectrum not demonstrated for other characterized fungal enzymes. These glucosides are faithfully processed by the dedicated MT to afford 4--methylglucosides. The resulting "unnatural products" show increased solubility, while representative polyketide methylglucosides also display increased stability against glycoside hydrolysis. Upon methylglucosidation, specific polyketides were found to attain cancer cell line-specific antiproliferative or matrix attachment inhibitory activities. These findings will guide genome mining for fungal GTs with novel substrate and product specificities, and empower the efficient combinatorial biosynthesis of a broad range of natural and unnatural glycosides in total biosynthetic or biocatalytic formats.
• Xu, Y. M., Wijeratne, E. M., Brooks, A. D., Tewary, P., Xuan, L. J., Wang, W. Q., Sayers, T. J., & Gunatilaka, A. A. (2018). Cytotoxic and other withanolides from aeroponically grown Physalis philadelphica. Phytochemistry, 152, 174-181.
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  Eleven withanolides including six previously undescribed compounds, 16β-hydroxyixocarpanolide, 24,25-dihydroexodeconolide C, 16,17-dehydro-24-epi-dioscorolide A, 17-epi-philadelphicalactone A, 16-deoxyphiladelphicalactone C, and 4-deoxyixocarpalactone A were isolated from aeroponically grown Physalis philadelphica. Structures of these withanolides were elucidated by the analysis of their spectroscopic (HRMS, 1D and 2D NMR, ECD) data and comparison with published data for related withanolides. Cytotoxic activity of all isolated compounds was evaluated against a panel of five human tumor cell lines (LNCaP, ACHN, UO-31, M14 and SK-MEL-28), and normal (HFF) cells. Of these, 17-epi-philadelphicalactone A, withaphysacarpin, philadelphicalactone C, and ixocarpalactone A exhibited cytotoxicity against ACHN, UO-31, M14 and SK-MEL-28, but showed no toxicity to HFF cells.
• Bashyal, B., Kithsiri Wijeratne, E., Tillotson, J., Arnold, A. E., Chapman, E., & Gunatilaka, L. (2017). Chlorinated dehydrocurvularins and alterperylenepoxide A from Alternaria sp. AST0039, a fungal endophyte of Astragalus lentiginosus. Journal of Natural Products, 80, 427-433.
• Gunatilaka, L., Bashyal, B. P., Wijeratne, K., Tillotson, J., Arnold, E., & Chapman, E. (2017). Chlorinated Dehydrocurvularins and Alterperylenepoxide A from Alternaria sp. AST0039, a Fungal Endophyte of Astragalus lentiginosus. Journal of Natural Products, 80, 427-433. doi:10.1021/acs.jnatprod.6b00960
• Gunatilaka, L., Luo, J., Sandberg, D. C., & Arnold, E. (2017). Montagnuphilones A–G, Azaphilones from Montagnulaceae sp. DM0194, a Fungal Endophyte of Submerged Roots of Persicaria amphibia. Journal of Natural Products, 80, 76-81. doi:10.1021/acs.jnatprod.6b00714
• Gunatilaka, L., Wijeratne, K., Gubiani, J. R., Shi, T., Aruajo, A. R., Arnold, E., & Chapman, E. (2017). An epigenetic modifier induces production of (10S)-verruculide B, an inhibitor of protein tyrosine phosphatases by Phoma sp. nov. LG0217, a fungal endophyte of Parkinsonia microphylla. Bioorganic and Medicinal Chemistry, 25, 1860-1866. doi:dx.doi.org/10.1016/j.bmc.2017.01.048.
• Gunatilaka, L., Xu, Y., Wijeratne, K., Babyak, A. L., Brooks, A. D., Tewary, P., Marks, H. R., Xuan, L., Wang, W., & Sayers, T. J. (2017). Withanolides from Aeroponically Grown Physalis peruviana and Their Selective Cytotoxicity to Prostate Cancer and Renal Carcinoma Cells. Journal of Natural Products, 80, 1981-1991. doi:10.1021/acs.jnatprod.6b01129
• Gunatilaka, L., Xu, Y., Wijeratne, K., Brooks, A. D., Henrich, C. J., Tewary, P., & Sayers, T. J. (2017). 17beta-Hydroxywithanolides as Sensitizers of Renal Carcinoma Cells to TRAIL–Induced Apoptosis: Structure–Activity Relationships. Journal of Medicinal Chemistry, 60, 3039-3051. doi:10.1021/acs.jmedchem.7b00069
• Luo, J., Xu, Y., Sandberg, D., Arnold, A. E., & Gunatilaka, L. (2017). Montagnuphilones A-G, azaphilones from Montagnulaceae sp. DM0194, a fungal endophyte of submerged roots of Persicaria amphibia. Journal of Natural Products, 80, 76-81.
• Tewary, P., Gunatilaka, L., & Sayers, T. (2017). Using natural products to promote caspase-8-dependent cancer cell death. Cancer Immunology Immunotherapy, 66, 223-231. doi:10.1007/s00262-016-1855-0
• Gunatilaka, A. L., Shekhar-Guturja, T., Gunaherath, G. B., Wijeratne, E. K., Lambert, J., Averette, A. F., Bahn, Y., Tripodi, F., Ammar, R., Sanglard, D., Andes, D., Nislow, C., Coccetti, P., Gingras, A., Heitman, J., & Cowen, L. E. (2016). Dual Action Small Molecule Potentiates Antifungal Efficacy, Blocks the Evolution of Drug Resistance, and Renders Resistant Pathogens Responsive to Therapy via Modulation of Multidrug Efflux and TOR Signaling. Nature Chemical Biology, 12, 867-875.
• Gunatilaka, A. L., Xu, Y., Bunting, D. P., Liu, M. X., & Bandaranayake, H. A. (2016). 17β-Hydroxy-18-acetoxywithanolides from Aeroponically Grown Physalis crassifolia and Their Potent and Selective Antiproliferative Activity for Prostate Cancer Cells. Journal of Natural Products, 79, 821-830.
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  When cultivated under aeroponic growth conditions, Physalis crassifolia produced eleven new withanolides (1–11) and seven known withanolides (12–18) including those obtained from the wild-crafted plant. The structures of the new withanolides were elucidated by the application of spectroscopic techniques, and the known withanolides were identified by comparison of their spectroscopic data with those reported. Withanolides 1–11 and 16 were evaluated for their potential anticancer activity using five tumor cell lines. Of these, the 17-hydroxy-18-acetoxywithanolides 1, 2, 6, 7, and 16 showed potent antiproliferative activity, with some having selectivity for prostate adenocarcinoma (LNCaP and PC-3M) compared to the breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460), and CNS glioma (SF-268) cell lines used. The cytotoxicity data obtained for 12–15, 17, and 19 have provided additional structure-activity relationship information for the 17-hydroxy-18-acetoxywithanolides.
• Gunatilaka, L., Efferth, T., Banerjee, M., Paul, N. W., Abdelfatah, S., & Arend et al., J. (2016). Biopiracy of natural products and good bioprospecting practice. Phytomedicine, 23, 166-173.
• Gunatilaka, L., Tillotson, J., Bashyal, B. P., Kang, M., Shi, T., Cruz, F. D., & Chapman, E. (2016). Selective inhibition of p97 by chlorinated analogues of dehydrocurvularin. Organic & Biomolecular Chemistry, 14, 5918-5921.
• Molnar, I., Gunatilaka, L., & 7 co-authors, C. (2016). Diversity-Oriented Combinatorial Biosynthesis of Hybrid Polyketide Scaffolds from Azaphilone and Benzenediol Lactone Biosynthons. Organic Letters, 18, 1262-1265.
• Wijeratne, E. M., Gunaherath, G. M., Chapla, V. M., Tillotson, J., de la Cruz, F., Kang, M., U Ren, J. M., Araujo, A. R., Arnold, A. E., Chapman, E., & Gunatilaka, A. A. (2016). Oxaspirol B with p97 Inhibitory Activity and Other Oxaspirols from Lecythophora sp. FL1375 and FL1031, Endolichenic Fungi Inhabiting Parmotrema tinctorum and Cladonia evansii. Journal of natural products, 79, 340-352.
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  A new metabolite, oxaspirol D (4), together with oxaspirols B (2) and C (3) were isolated from Lecythophora sp. FL1375, an endolichenic fungus isolated from Parmotrema tinctorum, whereas Lecythophora sp. FL1031 inhabiting the lichen Cladonia evansii afforded oxaspirols A (1), B (2), and C (3). Of these, oxaspirol B (2) showed moderate p97 ATPase inhibitory activity. A detailed characterization of all oxaspirols was undertaken because structures proposed for known oxaspirols have involved incomplete assignments of NMR spectroscopic data leading only to their planar structures. Thus, the naturally occurring isomeric mixture (2a and 2b) of oxaspirol B was separated as their diacetates (5a and 5b) and the structures and absolute configurations of 1, 2a, 2b, 3, and 4 were determined by the application of spectroscopic techniques including two-dimensional NMR and the modified Mosher's ester method. Oxaspirol B (2) and its diacetates 5a and 5b were evaluated for their ATPase inhibitory activities of p97, p97 mutants, and other ATP-utilizing enzymes, and only 2 was found to be active, indicating the requirement of some structural features in oxaspirols for their activity. Additional biochemical and cellular assays suggested that 2 was a reversible, non-ATP competitive, and specific inhibitor of p97.
• Lau, E. C., Mason, D. J., Eichhorst, N., Engelder, P., Mesa, C., Kithsiri Wijeratne, E. M., Gunaherath, G. M., Gunatilaka, A. A., La Clair, J. J., & Chapman, E. (2015). Functional chromatographic technique for natural product isolation. Organic & biomolecular chemistry, 13, 2255-2259.
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  Natural product discovery arises through a unique interplay between chromatographic purification and biological assays. Currently, most techniques used for natural product purification deliver leads without a defined biological action. We now describe a technique, referred to herein as functional chromatography, that deploys biological affinity as the matrix for compound isolation.
• Tao, S., Tillotson, J., Wijeratne, E. M., Xu, Y., Kang, M., Wu, T., Lau, E. C., Mesa, C., Mason, D. J., Brown, R. V., La Clair, J. J., Gunatilaka, A. A., Zhang, D. D., & Chapman, E. (2015). Withaferin A Analogs That Target the AAA+ Chaperone p97. ACS chemical biology, 10(8), 1916-1924.
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  Understanding the mode of action (MOA) of many natural products can be puzzling with mechanistic clues that seem to lack a common thread. One such puzzle lies in the evaluation of the antitumor properties of the natural product withaferin A (WFA). A variety of seemingly unrelated pathways have been identified to explain its activity, suggesting a lack of selectivity. We now show that WFA acts as an inhibitor of the chaperone, p97, both in vitro and in cell models in addition to inhibiting the proteasome in vitro. Through medicinal chemistry, we have refined the activity of WFA toward p97 and away from the proteasome. Subsequent studies indicated that these WFA analogs retained p97 activity and cytostatic activity in cell models, suggesting that the modes of action reported for WFA could be connected by proteostasis modulation. Through this endeavor, we highlight how the parallel integration of medicinal chemistry with chemical biology offers a potent solution to one of natures' intriguing molecular puzzles.
• Wei, H., Xu, Y., Espinosa-Artiles, P., Liu, M. X., Luo, J., U'Ren, J. M., Arnold, A. E., & Gunatilaka, A. A. (2015). Sesquiterpenes and other constituents of Xylaria sp. NC1214, a fungal endophyte of the moss Hypnum sp. Phytochemistry, 118, 102-8.
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  Oxygenated guaiane-type sesquiterpenes, xylaguaianols A-D (1-4), an iso-cadinane-type sesquiterpene isocadinanol A (5), and an α-pyrone 9-hydroxyxylarone (6), together with five known sesquiterpenes (7-11), and four known cytochalasins (12-15) were isolated from a culture broth of Xylaria sp. NC1214, a fungal endophyte of the moss Hypnum sp. The structures of all compounds were elucidated by the analysis of their spectroscopic data and relative configurations of 1-5 were determined with the help of NMR NOESY experiments. Cytochalasins C (12), D (13), and Q (14) were investigated for their cytotoxic activity against five tumor cell lines. Cytochalasin D showed significant cytotoxicity against all five cell lines, with IC50s ranging from 0.22 to 1.44 μM, whereas cytochalasins C and Q exhibited moderate, but selective cytotoxicity.
• Wijeratne, E. K., Xu, Y., Arnold, A. E., & Gunatilaka, A. L. (2015). Pulvinulin A, Graminin C, and cis-Gregatin B – New Natural Furanones from Pulvinula sp. 11120, a Fungal Endophyte of Cupressus arizonica. Natural Product Communications, 10(1), 107-111.
• Xu, Y., Bashyal, B. P., Liu, M. X., Espinosa-Artiles, P., U'Ren, J. M., Arnold, A. E., & Gunatilaka, A. L. (2015). Cytotoxic Cytochalasins and other Metabolites from Xylariales sp. FL0390, A Fungal Endophyte of the Spanish moss. Natural Product Communications, 10(10), 1655-1658.
• Xu, Y., Liu, M. X., Grunow, N., Wijeratne, E. M., Paine-Murrieta, G., Felder, S., Kris, R. M., & Gunatilaka, A. A. (2015). Discovery of Potent 17β-Hydroxywithanolides for Castration-Resistant Prostate Cancer by High-Throughput Screening of a Natural Products Library for Androgen-Induced Gene Expression Inhibitors. Journal of medicinal chemistry, 58(17), 6984-93.
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  Prostate cancer (PC) is the second most prevalent cancer among men in Western societies, and those who develop metastatic castration-resistant PC (CRPC) invariably succumb to the disease. The need for effective treatments for CRPC is a pressing concern, especially due to limited durable responses with currently employed therapies. Here, we demonstrate the successful application of a high-throughput gene-expression profiling assay directly targeting genes of the androgen receptor pathway to screen a natural products library leading to the identification of 17β-hydroxywithanolides 1-5, of which physachenolide D (5) exhibited potent and selective in vitro activity against two PC cell lines, LNCaP and PC-3. Epoxidation of 5 afforded physachenolide C (6) with higher potency and stability. Structure-activity relationships for withanolides as potential anti-PC agents are presented together with in vivo efficacy studies on compound 6, suggesting that 17β-hydroxywithanolides are promising candidates for further development as CRPC therapeutics.
• Xu, Y., Mafezoli, J., Oliveira, M. C., U'Ren, J. M., Arnold, A. E., & Gunatilaka, A. A. (2015). Anteaglonialides A-F and Palmarumycins CE1-CE3 from Anteaglonium sp. FL0768, a Fungal Endophyte of the Spikemoss Selaginella arenicola. Journal of natural products, 78(11), 2738-47.
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  Anteaglonialides A-F (1-6), bearing a spiro[6-(tetrahydro-7-furanyl)cyclohexane-1,2'-naphtho[1,8-de][1,3]-dioxin]-10-one skeleton, three new spirobisnaphthalenes, palmarumycins CE1-CE3 (7-9), nine known palmarumycin analogues, palmarumycins CP5 (10), CP4a (11), CP3 (12), CP17 (13), CP2 (14), and CP1 (15), CJ-12,371 (16), 4-O-methyl CJ-12,371 (17), and CP4 (18), together with a possible artifact, 4a(5)-anhydropalmarumycin CE2 (8a), and four known metabolites, O-methylherbarin (19), herbarin (20), herbaridine B (21), and hyalopyrone (22), were encountered in a cytotoxic extract of a potato dextrose agar culture of Anteaglonium sp. FL0768, an endophytic fungus of the sand spikemoss, Selaginella arenicola. The planar structures and relative configurations of the new metabolites 1-9 were elucidated by analysis of extensive spectroscopic data, and the absolute configuration of 1 was determined by the modified Mosher's ester method. Application of the modified Mosher's ester method combined with the NOESY data resulted in revision of the absolute configuration previously proposed for 10. Co-occurrence of 1-6 and 7-18 in this fungus led to the proposal that the anteagloniolides may be biogenetically derived from palmarumycins. Among the metabolites encountered, anteaglonialide F (6) and known palmarumycins CP3 (12) and CP1 (15) exhibited strong cytotoxic activity against the human Ewing's sarcoma cell line CHP-100, with IC50 values of 1.4, 0.5, and 1.6 μM, respectively.
• Bashyal, B. P., Wellensiek, B. P., Ramakrishnan, R., Faeth, S. H., Ahmad, N., & Gunatilaka, A. A. (2014). Altertoxins with potent anti-HIV activity from Alternaria tenuissima QUE1Se, a fungal endophyte of Quercus emoryi. Bioorganic & medicinal chemistry, 22(21), 6112-6.
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  Screening of a small library of natural product extracts derived from endophytic fungi of the Sonoran desert plants in a cell-based anti-HIV assay involving T-cells infected with the HIV-1 virus identified the EtOAc extract of a fermentation broth of Alternaria tenuissima QUE1Se inhabiting the stem tissue of Quercus emoryi as a promising candidate for further investigation. Bioactivity-guided fractionation of this extract led to the isolation and identification of two new metabolites, altertoxins V (1) and VI (2) together with the known compounds, altertoxins I (3), II (4), and III (5). The structures of 1 and 2 were determined by detailed spectroscopic analysis and those of 3-5 were established by comparison with reported data. When tested in our cell-based assay at concentrations insignificantly toxic to T-cells, altertoxins V (1), I (3), II (4), and III (5) completely inhibited replication of the HIV-1 virus at concentrations of 0.50, 2.20, 0.30, and 1.50 μM, respectively. Our findings suggest that the epoxyperylene structural scaffold in altertoxins may be manipulated to produce potent anti-HIV therapeutics.
• Gu, M., Yu, Y., Gunaherath, G. M., Gunatilaka, A. A., Li, D., & Sun, D. (2014). Structure-activity relationship (SAR) of withanolides to inhibit Hsp90 for its activity in pancreatic cancer cells. Investigational new drugs, 32(1), 68-74.
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  Withaferin A (WA), a naturally occurring steroidal lactone, directly binds to Hsp90 and leads to the degradation of Hsp90 client protein. The purpose of this study is to investigate the structure activity relationship (SAR) of withanolides for their inhibition of Hsp90 and anti-proliferative activities in pancreatic cancer cells. In pancreatic cancer Panc-1 cells, withaferin A (WA) and its four analogues withanolide E (WE), 4-hydroxywithanolide E (HWE), 3-aziridinylwithaferin A (AzWA) inhibited cell proliferation with IC50 ranged from 1.0 to 2.8 μM. WA, WE, HWE, and AzWA also induced caspase-3 activity by 21-, 6-, 11- and 15-fold, respectively, in Panc-1 cells, while withaperuvin (WP) did not show any activity. Our data showed that WA, WE, HWE, and AzWA, but not WP, all directly bound to Hsp90 and induced Hsp90 aggregation,hence inhibited Hsp90 chaperone activity to induce degradation of Hsp90 client proteins Akt and Cdk4 through proteasome-dependent pathway in pancreatic cancer cells. However, only WA, HWE and AzWA disrupted Hsp90-Cdc37 complexes but not WE and WP. SAR study suggested that the C-5(6)-epoxy functional group contributes considerably for withanolide to bind to Hsp90, inhibit Hsp90 chaperone activity, and result in Hsp90 client protein depletion. Meanwhile, the hydroxyl group at C-4 of ring A may enhance withanolide to inhibit Hsp90 activity and disrupt Hsp90-Cdc37 interaction. These SAR data provide possible mechanisms of anti-proliferative action of withanolides.
• Gunatilaka, L. (2014). Traditional Medicine Inspired Discovery of Natural Product-Based Drugs for the Treatment of Modern Day Diseases. Euro. J. Integrative Medicine, 6, 694.
• Kang, M. J., Wu, T., Wijeratne, E. M., Lau, E. C., Mason, D. J., Mesa, C., Tillotson, J., Zhang, D. D., Gunatilaka, A. A., La Clair, J. J., & Chapman, E. (2014). Functional chromatography reveals three natural products that target the same protein with distinct mechanisms of action. Chembiochem : a European journal of chemical biology, 15(14), 2125-31.
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  Access to lead compounds with defined molecular targets continues to be a barrier to the translation of natural product resources. As a solution, we developed a system that uses discrete, recombinant proteins as the vehicles for natural product isolation. Here, we describe the use of this functional chromatographic method to identify natural products that bind to the AAA+ chaperone, p97, a promising cancer target. Application of this method to a panel of fungal and plant extracts identified rheoemodin, 1-hydroxydehydroherbarin, and phomapyrrolidone A as distinct p97 modulators. Excitingly, each of these molecules displayed a unique mechanism of p97 modulation. This discovery provides strong support for the application of functional chromatography to the discovery of protein modulators that would likely escape traditional high-throughput or phenotypic screening platforms.
• Luo, J., Wang, X., Xu, Y., U'Ren, J. M., Arnold, A. E., Kong, L., & Gunatilaka, A. A. (2014). Delitschiapyrone A, a pyrone-naphthalenone adduct bearing a new pentacyclic ring system from the leaf-associated fungus Delitschia sp. FL1581. Organic letters, 16(22), 5944-7.
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  Delitschiapyrone A (1), an α-pyrone-naphthalenone adduct with an unprecedented pentacyclic ring system, was isolated from a solid culture of the leaf-associated fungus Delitschia sp. FL1581. The structure of 1 was elucidated by spectroscopic analysis and X-ray crystallography, and its absolute configuration was defined by experimental and calculated ECD. Biosynthetically, the unique 6/6/5/7/6 pentacyclic core of 1 may be formed by an intermolecular Diels-Alder-type addition of the precursors derived from (1'R)-2',3'-dihydropyrenocine C (2) and 6-ethyl-2,7-dimethoxyjuglone (3) found to co-occur with 1 in this fungus.
• Mafezoli, J., Oliveira, M. C., Paiva, J. R., Sousa, A. H., Lima, M. A., Júnior, J. N., Barbosa, F. G., Wijeratne, E. M., & Gunatilaka, A. A. (2014). Stereo and regioselective microbial reduction of the clerodane diterpene 3,12-dioxo-15,16-epoxy-4-hydroxycleroda-13(16),14-diene. Natural product communications, 9(6), 759-62.
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  The biotransformation of the clerodane diterpene, 3,12-dioxo-15,16-epoxy-4-hydroxy-cleroda-13(16),14-diene (1), obtained from Croton micans var. argyroglossum (Baill.) Mill., was investigated for the first time. Whole cells of Cunninghamella echinulata and Rhizopus stolonifer were used as enzymatic systems, and with both fungi the only biotransformation product obtained was the new ent-neo-clerodane diterpene (3R,4S,5S,8S,9R,10S)-3,4-dihydroxy-15,16-epoxy-12-oxo-cleroda-13(16),14-diene (2a). The absolute stereochemistry of 2a was inferred by comparison of its optical rotation with those of the chemical reduction product of 1 and its quasienantiomer 2c.
• Wijeratne, E. M., Espinosa-Artiles, P., Gruener, R., & Gunatilaka, A. A. (2014). Thielavialides A-E, nor-spiro-azaphilones, and a bis-spiro-azaphilone from Thielavia sp. PA0001, an endophytic fungus isolated from aeroponically grown Physalis alkekengi. Journal of natural products, 77(6), 1467-72.
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  Four new nor-spiro-azaphilones, thielavialides A-D (1- 4), a new bis-spiro-azaphilone, thielavialide E (5), together with pestafolide A (6), were isolated from the endophytic fungal strain, Thielavia sp. PA0001, occurring in the healthy leaf tissue of aeroponically grown Physalis alkekengi. The structures and relative configurations of 1-5 were established on the basis of their MS and NMR data. Possible biosynthetic pathways to thielavialides A-E (1- 5) from pestafolide A (6), some involving a Favorskii-like rearrangement, are proposed.
• Wijeratne, E. M., Xu, Y., Scherz-Shouval, R., Marron, M. T., Rocha, D. D., Liu, M. X., Costa-Lotufo, L. V., Santagata, S., Lindquist, S., Whitesell, L., & Gunatilaka, A. A. (2014). Structure-activity relationships for withanolides as inducers of the cellular heat-shock response. Journal of medicinal chemistry, 57(7), 2851-63.
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  To understand the relationship between the structure and the remarkably diverse bioactivities reported for withanolides, we obtained withaferin A (WA; 1) and 36 analogues (2-37) and compared their cytotoxicity to cytoprotective heat-shock-inducing activity (HSA). By analyzing structure-activity relationships for the series, we found that the ring A enone is essential for both bioactivities. Acetylation of 27-OH of 4-epi-WA (28) to 33 enhanced both activities, whereas introduction of β-OH to WA at C-12 (29) and C-15 (30) decreased both activities. Introduction of β-OAc to 4,27-diacetyl-WA (16) at C-15 (37) decreased HSA without affecting cytotoxicity, but at C-12 (36), it had minimal effect. Importantly, acetylation of 27-OH, yielding 15 from 1, 16 from 14, and 35 from 34, enhanced HSA without increasing cytotoxicity. Our findings demonstrate that the withanolide scaffold can be modified to enhance HSA selectively, thereby assisting development of natural product-inspired drugs to combat protein aggregation-associated diseases by stimulating cellular defense mechanisms.
• Xu, Y., Zhou, T., Zhang, S., Espinosa-Artiles, P., Wang, L., Zhang, W., Lin, M., Gunatilaka, A. A., Zhan, J., & Molnár, I. (2014). Diversity-oriented combinatorial biosynthesis of benzenediol lactone scaffolds by subunit shuffling of fungal polyketide synthases. Proceedings of the National Academy of Sciences of the United States of America, 111(34), 12354-9.
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  Combinatorial biosynthesis aspires to exploit the promiscuity of microbial anabolic pathways to engineer the synthesis of new chemical entities. Fungal benzenediol lactone (BDL) polyketides are important pharmacophores with wide-ranging bioactivities, including heat shock response and immune system modulatory effects. Their biosynthesis on a pair of sequentially acting iterative polyketide synthases (iPKSs) offers a test case for the modularization of secondary metabolic pathways into "build-couple-pair" combinatorial synthetic schemes. Expression of random pairs of iPKS subunits from four BDL model systems in a yeast heterologous host created a diverse library of BDL congeners, including a polyketide with an unnatural skeleton and heat shock response-inducing activity. Pairwise heterocombinations of the iPKS subunits also helped to illuminate the innate, idiosyncratic programming of these enzymes. Even in combinatorial contexts, these biosynthetic programs remained largely unchanged, so that the iPKSs built their cognate biosynthons, coupled these building blocks into chimeric polyketide intermediates, and catalyzed intramolecular pairing to release macrocycles or α-pyrones. However, some heterocombinations also provoked stuttering, i.e., the relaxation of iPKSs chain length control to assemble larger homologous products. The success of such a plug and play approach to biosynthesize novel chemical diversity bodes well for bioprospecting unnatural polyketides for drug discovery.
• von Bierberstein, P., Yaming, X., Gunatilaka, L., & R. Gruener, R. (2014). Biomass production and withaferin A synthesis by Withania somnifera grown in aeroponics and hydroponics. HortScience, 2014, 49, ., 49, 1506–1509.
• Furtado, R. A., M., G., Bastos, J. K., & A., A. (2013). Microbial biotransformation of 16a,17-epoxy-ent-kaurane-19-oic acid by beauveria sulfurescens ATCC 7159-F. Natural Product Communications, 8(8), 1041-1044.
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  PMID: 24079162;Abstract: Biotransformation of 16α,17-epoxy-ent-kaurane-19-oic acid (1) by Beauveria sulfurescens ATCC 7159-F led to the production of a new ent-kaurane diterpenoid, 7β,17-dihydroxy-ent-kaur-15-en-19-oic acid (7), and four other ent-kauranes (8 - 11), all of which were identified as their methyl esters. Compounds 9 and 10 were found to be new stereoisomers. Structures of these were established by the extensive usage of their spectroscopic characteristics.
• Gunatilaka, L. -., Furtado, R., Gunaherath, G. B., & Bastos, J. K. (2013). Microbial Biotransformation of 16a,17-Epoxy-ent-kaurane-19-oic acid by Beauveria sulfurescens ATCC 7159-F. Natural Product Communications, 8, 1041-1044.
• Gunatilaka, L. -., Wanigasekara, W. M., Wijeratne, E. M., & Arnold, A. E. (2013). 10'-Deoxy-10'a-hydroxyascochlorin, a New Cell Migration Inhibitor and Other Metabolites from Acremonium sp., a Fungal Endophyte in Ephedra trifurca. Natural Product Communications, 8, 601-604.
• Gunatilaka, L., Gunatilaka, L. -., Gunaherath, G. M., Marron, M. T., Wijeratne, E. M., & Whitesell, L. (2013). Synthesis and biological evaluation of novobiocin analogues as potential heat shock protein 90 inhibitors. Bioorganic & medicinal chemistry, 21(17), 5118-5129.
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  Recent studies have shown that novobiocin (NB), a member of the coumermycin (CA) family of antibiotics with demonstrated DNA gyrase inhibitory activity, inhibits Heat shock protein 90 (HSP90) by binding weakly to a putative ATP-binding site within its C-terminus. To develop more potent HSP90 inhibitors that target this site and to define structure-activity relationships (SARs) for this class of compounds, we have synthesized twenty seven 3-amido-7-noviosylcoumarin analogues starting from NB and CA. These were evaluated for evidence of HSP90 inhibition using several biological assays including inhibition of cell proliferation and cell cycle arrest, induction of the heat shock response, inhibition of luciferase-refolding in vitro, and depletion of the HSP90 client protein c-erbB-2/HER-2/neu (HER2). This SAR study revealed that a substantial increase in biological activity can be achieved by introduction of an indole-2-carboxamide group in place of 4-hydroxy-isopentylbenzamido group at C-3 of NB in addition to removal/derivatization of the 4-hydroxyl group from the coumarin ring. Methylation of the 4-hydroxyl group in the coumarin moiety moderately increased biological activity as shown by compounds 11 and 13. Our most potent new analogue 19 demonstrated biological activities consistent with known HSP90-binding agents, but with greater potency than NB.
• Hoffman, M. T., Gunatilaka, M. K., Wijeratne, K., Gunatilaka, L., & Arnold, A. E. (2013). Endohyphal Bacterium Enhances Production of Indole-3-Acetic Acid by a Foliar Fungal Endophyte. PLoS ONE, 8(9).
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  PMID: 24086270;PMCID: PMC3782478;Abstract: Numerous plant pathogens, rhizosphere symbionts, and endophytic bacteria and yeasts produce the important phytohormone indole-3-acetic acid (IAA), often with profound effects on host plants. However, to date IAA production has not been documented among foliar endophytes -- the diverse guild of primarily filamentous Ascomycota that live within healthy, above-ground tissues of all plant species studied thus far. Recently bacteria that live within hyphae of endophytes (endohyphal bacteria) have been detected, but their effects have not been studied previously. Here we show not only that IAA is produced in vitro by a foliar endophyte (here identified as Pestalotiopsis aff. neglecta, Xylariales), but that IAA production is enhanced significantly when the endophyte hosts an endohyphal bacterium (here identified as Luteibacter sp., Xanthomonadales). Both the endophyte and the endophyte/bacterium complex appear to rely on an L-tryptophan dependent pathway for IAA synthesis. The bacterium can be isolated from the fungus when the symbiotic complex is cultivated at 36°C. In pure culture the bacterium does not produce IAA. Culture filtrate from the endophyte-bacterium complex significantly enhances growth of tomato in vitro relative to controls and to filtrate from the endophyte alone. Together these results speak to a facultative symbiosis between an endophyte and endohyphal bacterium that strongly influences IAA production, providing a new framework in which to explore endophyte-plant interactions. © 2013 Hoffman et al.
• Hoffman, M. T., Gunatilaka, M. K., Wijeratne, K., Gunatilaka, L., & Arnold, A. E. (2013). Endohyphal bacterium enhances production of indole-3-acetic Acid by a foliar fungal endophyte. PloS one, 8(9).
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  Numerous plant pathogens, rhizosphere symbionts, and endophytic bacteria and yeasts produce the important phytohormone indole-3-acetic acid (IAA), often with profound effects on host plants. However, to date IAA production has not been documented among foliar endophytes -- the diverse guild of primarily filamentous Ascomycota that live within healthy, above-ground tissues of all plant species studied thus far. Recently bacteria that live within hyphae of endophytes (endohyphal bacteria) have been detected, but their effects have not been studied previously. Here we show not only that IAA is produced in vitro by a foliar endophyte (here identified as Pestalotiopsis aff. neglecta, Xylariales), but that IAA production is enhanced significantly when the endophyte hosts an endohyphal bacterium (here identified as Luteibacter sp., Xanthomonadales). Both the endophyte and the endophyte/bacterium complex appear to rely on an L-tryptophan dependent pathway for IAA synthesis. The bacterium can be isolated from the fungus when the symbiotic complex is cultivated at 36°C. In pure culture the bacterium does not produce IAA. Culture filtrate from the endophyte-bacterium complex significantly enhances growth of tomato in vitro relative to controls and to filtrate from the endophyte alone. Together these results speak to a facultative symbiosis between an endophyte and endohyphal bacterium that strongly influences IAA production, providing a new framework in which to explore endophyte-plant interactions.
• Kamal, G., Marron, M. T., Wijeratne, E. K., Whitesell, L., & Gunatilaka, A. L. (2013). Synthesis and biological evaluation of novobiocin analogues as potential heat shock protein 90 inhibitors. Bioorganic and Medicinal Chemistry, 21(17), 5118-5129.
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  PMID: 23859777;Abstract: Recent studies have shown that novobiocin (NB), a member of the coumermycin (CA) family of antibiotics with demonstrated DNA gyrase inhibitory activity, inhibits Heat shock protein 90 (HSP90) by binding weakly to a putative ATP-binding site within its C-terminus. To develop more potent HSP90 inhibitors that target this site and to define structure-activity relationships (SARs) for this class of compounds, we have synthesized twenty seven 3-amido-7- noviosylcoumarin analogues starting from NB and CA. These were evaluated for evidence of HSP90 inhibition using several biological assays including inhibition of cell proliferation and cell cycle arrest, induction of the heat shock response, inhibition of luciferase-refolding in vitro, and depletion of the HSP90 client protein c-erbB-2/HER-2/neu (HER2). This SAR study revealed that a substantial increase in biological activity can be achieved by introduction of an indole-2-carboxamide group in place of 4-hydroxy-isopentylbenzamido group at C-3 of NB in addition to removal/derivatization of the 4-hydroxyl group from the coumarin ring. Methylation of the 4-hydroxyl group in the coumarin moiety moderately increased biological activity as shown by compounds 11 and 13. Our most potent new analogue 19 demonstrated biological activities consistent with known HSP90-binding agents, but with greater potency than NB. © 2013 Elsevier Ltd. All rights reserved.
• M., E., Hongping, H. e., Franzblau, S. G., Hoffman, A. M., & A., A. (2013). Phomapyrrolidones A-C, Antitubercular Alkaloids from the Endophytic Fungus Phoma sp. NRRL 46751. Journal of Natural Products, 76(10), 1860-1865.
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  PMID: 24079882;PMCID: PMC3896239;Abstract: Three new alkaloids, phomapyrrolidones A-C (1-3), bearing a cyclopenta[b]fluorene ring system were isolated from the mycelium extract of the endophytic fungal strain Phoma sp. NRRL 46751, inhabiting Saurauia scaberrinae. Methylation of 1 afforded its N-methyl derivative 4. The planar structures and relative configurations of 1-4 were elucidated by extensive spectroscopic analysis. Phomapyrrolidones B (2) and C (3) exhibited weak antitubercular activity at subcytotoxic concentrations. © 2013 The American Chemical Society and American Society of Pharmacognosy.
• M., W., M., E., Arnold, A. E., & A., A. (2013). 10′-deoxy-10′α-hydroxyascochlorin, a new cell migration inhibitor and other metabolites from Acremonium sp., a fungal endophyte in Ephedra trifurca. Natural Product Communications, 8(5), 601-604.
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  Abstract: A new ascochlorin, 10′-deoxy-10′α-hydroxyascochlorin (1), together with ascofuranone (2), ascochlorin (3), and 4′,5′-dihydro- 4′β-hydroxyascochlorin (4) were isolated from Acremonium sp. LG0808, an endophytic fungal strain occurring in the stem tissue of the medicinal plant, Ephedra trifurca. The structure of 1 was elucidated on the basis of its high-resolution mass spectrometric, and 1D and 2D NMR spectroscopic data. Compounds 1 and 3 inhibited migration of metastatic prostate cancer cells, PC-3M. In addition, 3 exhibited moderately selective cytotoxicity against the NCI-H460 (non-small cell lung cancer) cell line, but its dimethyl ether (6) showed selective activity against PC-3M, MCF-7 (breast cancer), and MDA-MB-231 (metastatic breast cancer) cell lines.
• Mancang, G. u., Yanke, Y. u., Gunaherath, G. B., Gunatilaka, A., Dapeng, L. i., & Sun, D. (2013). Structure-activity relationship (SAR) of withanolides to inhibit Hsp90 for its activity in pancreatic cancer cells. Investigational New Drugs, 1-7.
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  Abstract: Withaferin A (WA), a naturally occurring steroidal lactone, directly binds to Hsp90 and leads to the degradation of Hsp90 client protein. The purpose of this study is to investigate the structure activity relationship (SAR) of withanolides for their inhibition of Hsp90 and anti-proliferative activities in pancreatic cancer cells. In pancreatic cancer Panc-1 cells, withaferin A (WA) and its four analogues withanolide E (WE), 4-hydroxywithanolide E (HWE), 3-aziridinylwithaferin A (AzWA) inhibited cell proliferation with IC50 ranged from 1.0 to 2.8 μM. WA, WE, HWE, and AzWA also induced caspase-3 activity by 21-, 6-, 11- and 15-fold, respectively, in Panc-1 cells, while withaperuvin (WP) did not show any activity. Our data showed that WA, WE, HWE, and AzWA, but not WP, all directly bound to Hsp90 and induced Hsp90 aggregation,hence inhibited Hsp90 chaperone activity to induce degradation of Hsp90 client proteins Akt and Cdk4 through proteasome-dependent pathway in pancreatic cancer cells. However, only WA, HWE and AzWA disrupted Hsp90-Cdc37 complexes but not WE and WP. SAR study suggested that the C-5(6)-epoxy functional group contributes considerably for withanolide to bind to Hsp90, inhibit Hsp90 chaperone activity, and result in Hsp90 client protein depletion. Meanwhile, the hydroxyl group at C-4 of ring A may enhance withanolide to inhibit Hsp90 activity and disrupt Hsp90-Cdc37 interaction. These SAR data provide possible mechanisms of anti-proliferative action of withanolides. © 2013 Springer Science+Business Media New York.
• Wellensiek, B. P., Ramakrishnan, R., Bashyal, B. P., Eason, Y., Gunatilaka, A. A., & Ahmad, N. (2013). Inhibition of HIV-1 Replication by Secondary Metabolites From Endophytic Fungi of Desert Plants. The open virology journal, 7.
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  Most antiretroviral drugs currently in use to treat an HIV-1 infection are chemically synthesized and lead to the development of viral resistance, as well as cause severe toxicities. However, a largely unexplored source for HIV-1 drug discovery is endophytic fungi that live in a symbiotic relationship with plants. These fungi produce biologically active secondary metabolites, which are natural products that are beneficial to the host. We prepared several hundred extracts from endophytic fungi of desert plants and evaluated the inhibitory effects on HIV-1 replication of those extracts that showed less than 30% cytotoxicity in T-lymphocytes. Those extracts that inhibited viral replication were fractionated in order to isolate the compounds responsible for activity. Multiple rounds of fractionation and antiviral evaluation lead to the identification of four compounds, which almost completely impede HIV-1 replication. These studies demonstrate that metabolites from endophytic fungi of desert plants can serve as a viable source for identifying potent inhibitors of HIV-1 replication.
• Wijeratne, E. M., He, H., Franzblau, S. G., Hoffman, A. M., & Gunatilaka, A. A. (2013). Phomapyrrolidones A-C, antitubercular alkaloids from the endophytic fungus Phoma sp. NRRL 46751. Journal of natural products, 76(10), 1860-1865.
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  Three new alkaloids, phomapyrrolidones A-C (1-3), bearing a cyclopenta[b]fluorene ring system were isolated from the mycelium extract of the endophytic fungal strain Phoma sp. NRRL 46751, inhabiting Saurauia scaberrinae. Methylation of 1 afforded its N-methyl derivative 4. The planar structures and relative configurations of 1-4 were elucidated by extensive spectroscopic analysis. Phomapyrrolidones B (2) and C (3) exhibited weak antitubercular activity at subcytotoxic concentrations.
• Xu, Y., Espinosa-Artiles, P., Liu, M. X., Arnold, A. E., & A., A. (2013). Secoemestrin D, a cytotoxic epitetrathiodioxopiperizine, and emericellenes a-e, five sesterterpenoids from emericella sp. AST0036, a fungal endophyte of astragalus lentiginosus 1. Journal of Natural Products, 76(12), 2330-2336.
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  PMID: 24251417;Abstract: A new epitetrathiodioxopiperizine, secoemestrin D (1), and five sesterterpenoids bearing a new carbon skeleton, emericellenes A-E (2-6), together with previously known fungal metabolites, sterigmatocystin (7), arugosin C (8), and epiisoshamixanthone (9), were obtained from the endophytic fungal strain Emericella sp. AST0036 isolated from a healthy leaf tissue of Astragalus lentiginosus. The planar structures and relative configurations of the new metabolites 1-6 were elucidated using MS and 1D and 2D NMR spectroscopic data. All compounds were evaluated for their potential anticancer activity using a panel of six tumor cell lines and normal human fibroblast cells. Only metabolites 1 and 7 showed cytotoxic activity. More importantly, secoemestrin D (1) exhibited significant cytotoxicity with IC50 values ranging from 0.06 to 0.24 μM and moderate selectivity to human glioma (SF-268) and metastatic breast adenocarcinoma (MDA-MB-231) cell lines. © 2013 The American Chemical Society and American Society of Pharmacognosy.
• Xu, Y., Espinosa-Artiles, P., Liu, M. X., Arnold, A. E., & Gunatilaka, A. A. (2013). Secoemestrin D, a cytotoxic epitetrathiodioxopiperizine, and emericellenes A-E, five sesterterpenoids from Emericella sp. AST0036, a fungal endophyte of Astragalus lentiginosus1. Journal of natural products, 76(12), 2330-2336.
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  A new epitetrathiodioxopiperizine, secoemestrin D (1), and five sesterterpenoids bearing a new carbon skeleton, emericellenes A-E (2-6), together with previously known fungal metabolites, sterigmatocystin (7), arugosin C (8), and epiisoshamixanthone (9), were obtained from the endophytic fungal strain Emericella sp. AST0036 isolated from a healthy leaf tissue of Astragalus lentiginosus. The planar structures and relative configurations of the new metabolites 1-6 were elucidated using MS and 1D and 2D NMR spectroscopic data. All compounds were evaluated for their potential anticancer activity using a panel of six tumor cell lines and normal human fibroblast cells. Only metabolites 1 and 7 showed cytotoxic activity. More importantly, secoemestrin D (1) exhibited significant cytotoxicity with IC50 values ranging from 0.06 to 0.24 μM and moderate selectivity to human glioma (SF-268) and metastatic breast adenocarcinoma (MDA-MB-231) cell lines.
• Xu, Y., Espinosa-Artiles, P., Schubert, V., Xu, Y., Zhang, W., Lin, M., Gunatilaka, A. A., Süssmuth, R., & Molnár, I. (2013). Characterization of the biosynthetic genes for 10,11-dehydrocurvularin, a heat shock response-modulating anticancer fungal polyketide from Aspergillus terreus. Applied and environmental microbiology, 79(6).
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  10,11-Dehydrocurvularin is a prevalent fungal phytotoxin with heat shock response and immune-modulatory activities. It features a dihydroxyphenylacetic acid lactone polyketide framework with structural similarities to resorcylic acid lactones like radicicol or zearalenone. A genomic locus was identified from the dehydrocurvularin producer strain Aspergillus terreus AH-02-30-F7 to reveal genes encoding a pair of iterative polyketide synthases (A. terreus CURS1 [AtCURS1] and AtCURS2) that are predicted to collaborate in the biosynthesis of 10,11-dehydrocurvularin. Additional genes in this locus encode putative proteins that may be involved in the export of the compound from the cell and in the transcriptional regulation of the cluster. 10,11-Dehydrocurvularin biosynthesis was reconstituted in Saccharomyces cerevisiae by heterologous expression of the polyketide synthases. Bioinformatic analysis of the highly reducing polyketide synthase AtCURS1 and the nonreducing polyketide synthase AtCURS2 highlights crucial biosynthetic programming differences compared to similar synthases involved in resorcylic acid lactone biosynthesis. These differences lead to the synthesis of a predicted tetraketide starter unit that forms part of the 12-membered lactone ring of dehydrocurvularin, as opposed to the penta- or hexaketide starters in the 14-membered rings of resorcylic acid lactones. Tetraketide N-acetylcysteamine thioester analogues of the starter unit were shown to support the biosynthesis of dehydrocurvularin and its analogues, with yeast expressing AtCURS2 alone. Differential programming of the product template domain of the nonreducing polyketide synthase AtCURS2 results in an aldol condensation with a different regiospecificity than that of resorcylic acid lactones, yielding the dihydroxyphenylacetic acid scaffold characterized by an S-type cyclization pattern atypical for fungal polyketides.
• Yuquan, X. u., Espinosa-Artiles, P., Schubert, V., Xu, Y., Zhang, W., Lin, M., Gunatilaka, A. L., Süssmuth, R., & Molnár, I. (2013). Characterization of the biosynthetic genes for 10,11- dehydrocurvularin, a heat shock response-modulating anticancer fungal polyketide from Aspergillus terreus. Applied and Environmental Microbiology, 79(6), 2038-2047.
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  PMID: 23335766;PMCID: PMC3592213;Abstract: 10,11-Dehydrocurvularin is a prevalent fungal phytotoxin with heat shock response and immune-modulatory activities. It features a dihydroxyphenylacetic acid lactone polyketide framework with structural similarities to resorcylic acid lactones like radicicol or zearalenone. A genomic locus was identified from the dehydrocurvularin producer strain Aspergillus terreus AH-02- 30-F7 to reveal genes encoding a pair of iterative polyketide synthases (A. terreus CURS1 [AtCURS1] and AtCURS2) that are predicted to collaborate in the biosynthesis of 10,11-dehydrocurvularin. Additional genes in this locus encode putative proteins that may be involved in the export of the compound from the cell and in the transcriptional regulation of the cluster. 10,11-Dehydrocurvularin biosynthesis was reconstituted in Saccharomyces cerevisiae by heterologous expression of the polyketide synthases. Bioinformatic analysis of the highly reducing polyketide synthase AtCURS1 and the nonreducing polyketide synthase AtCURS2 highlights crucial biosynthetic programming differences compared to similar synthases involved in resorcylic acid lactone biosynthesis. These differences lead to the synthesis of a predicted tetraketide starter unit that forms part of the 12-membered lactone ring of dehydrocurvularin, as opposed to the penta- or hexaketide starters in the 14-membered rings of resorcylic acid lactones. Tetraketide N-acetylcysteamine thioester analogues of the starter unit were shown to support the biosynthesis of dehydrocurvularin and its analogues, with yeast expressing AtCURS2 alone. Differential programming of the product template domain of the nonreducing polyketide synthase AtCURS2 results in an aldolcondensation with a different regiospecificity than that of resorcylic acid lactones, yielding the dihydroxyphenylacetic acid scaffold characterized by an S-type cyclization pattern atypical for fungal polyketides. © 2013, American Society for Microbiology.
• Gunatilaka, A. L. (2012). Plant Natural Products. Natural Products in Chemical Biology, 1-29.
• M., E., Bashyal, B. P., Liu, M. X., Rocha, D. D., M., G., U'Ren, J. M., Gunatilaka, M. K., Arnold, A. E., Whitesell, L., & A., A. (2012). Geopyxins A-E, ent -Kaurane diterpenoids from endolichenic fungal strains geopyxis aff. majalis and Geopyxis sp. AZ0066: Structure-activity relationships of geopyxins and their analogues(1). Journal of Natural Products, 75(3), 361-369.
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  PMID: 22264149;PMCID: PMC3359839;Abstract: Four new ent-kaurane diterpenoids, geopyxins A-D (1-4), were isolated from Geopyxis aff. majalis, a fungus occurring in the lichen Pseudevernia intensa, whereas Geopyxis sp. AZ0066 inhabiting the same host afforded two new ent-kaurane diterpenoids, geopyxins E and F (5 and 6), together with 1 and 3. The structures of 1-6 were established on the basis of their spectroscopic data, while the absolute configurations were assigned using modified Mosher's ester method. Methylation of 1-3, 5, and 6 gave their corresponding methyl esters 7-11. On acetylation, 1 and 7 yielded their corresponding monoacetates 12 and 14 and diacetates 13 and 15. All compounds were evaluated for their cytotoxic and heat-shock induction activities. Compounds 2, 7-10, 12, 14, and 15 showed cytotoxic activity in the low micromolar range against all five cancer cell lines tested, but only compounds 7-9, 14, and 15 were found to activate the heat-shock response at similar concentrations. From a preliminary structure-activity perspective, the electrophilic α,β-unsaturated ketone carbonyl motif present in all compounds except 6 and 11 was found to be necessary but not sufficient for both cytotoxicity and heat-shock activation. © 2012 The American Chemical Society and American Society of Pharmacognosy.
• Santagata, S., Xu, Y., M., E., Kontnik, R., Rooney, C., Perley, C. C., Kwon, H., Clardy, J., Kesari, S., Whitesell, L., Lindquist, S., & A., A. (2012). Using the heat-shock response to discover anticancer compounds that target protein homeostasis. ACS Chemical Biology, 7(2), 340-349.
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  PMID: 22050377;PMCID: PMC3291478;Abstract: Unlike normal tissues, cancers experience profound alterations in protein homeostasis. Powerful innate adaptive mechanisms, especially the transcriptional response regulated by Heat Shock Factor 1 (HSF1), are activated in cancers to enable survival under these stressful conditions. Natural products that further tax these stress responses can overwhelm the ability to cope and could provide leads for the development of new, broadly effective anticancer drugs. To identify compounds that drive the HSF1-dependent stress response, we evaluated over 80,000 natural and synthetic compounds as well as partially purified natural product extracts using a reporter cell line optimized for high-throughput screening. Surprisingly, many of the strongly active compounds identified were natural products representing five diverse chemical classes (limonoids, curvularins, withanolides, celastraloids, and colletofragarones). All of these compounds share the same chemical motif, an α,β- unsaturated carbonyl functionality, with strong potential for thiol-reactivity. Despite the lack of a priori mechanistic requirements in our primary phenotypic screen, this motif was found to be necessary albeit not sufficient, for both heat-shock activation and inhibition of glioma tumor cell growth. Within the withanolide class, a promising therapeutic index for the compound withaferin A was demonstrated in vivo using a stringent orthotopic human glioma xenograft model in mice. Our findings reveal that diverse organisms elaborate structurally complex thiol-reactive metabolites that act on the stress responses of heterologous organisms including humans. From a chemical biology perspective, they define a robust approach for discovering candidate compounds that target the malignant phenotype by disrupting protein homeostasis. © 2011 American Chemical Society.
• Santagata, S., Xu, Y., Wijeratne, E. M., Kontnik, R., Rooney, C., Perley, C. C., Kwon, H., Clardy, J., Kesari, S., Whitesell, L., Lindquist, S., & Gunatilaka, A. A. (2012). Using the heat-shock response to discover anticancer compounds that target protein homeostasis. ACS chemical biology, 7(2).
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  Unlike normal tissues, cancers experience profound alterations in protein homeostasis. Powerful innate adaptive mechanisms, especially the transcriptional response regulated by Heat Shock Factor 1 (HSF1), are activated in cancers to enable survival under these stressful conditions. Natural products that further tax these stress responses can overwhelm the ability to cope and could provide leads for the development of new, broadly effective anticancer drugs. To identify compounds that drive the HSF1-dependent stress response, we evaluated over 80,000 natural and synthetic compounds as well as partially purified natural product extracts using a reporter cell line optimized for high-throughput screening. Surprisingly, many of the strongly active compounds identified were natural products representing five diverse chemical classes (limonoids, curvularins, withanolides, celastraloids, and colletofragarones). All of these compounds share the same chemical motif, an α,β-unsaturated carbonyl functionality, with strong potential for thiol-reactivity. Despite the lack of a priori mechanistic requirements in our primary phenotypic screen, this motif was found to be necessary albeit not sufficient, for both heat-shock activation and inhibition of glioma tumor cell growth. Within the withanolide class, a promising therapeutic index for the compound withaferin A was demonstrated in vivo using a stringent orthotopic human glioma xenograft model in mice. Our findings reveal that diverse organisms elaborate structurally complex thiol-reactive metabolites that act on the stress responses of heterologous organisms including humans. From a chemical biology perspective, they define a robust approach for discovering candidate compounds that target the malignant phenotype by disrupting protein homeostasis.
• Gao, S., Xu, Y., Valeriote, F. A., & A., A. (2011). Pierreiones A - D, solid tumor selective pyranoisoflavones and other cytotoxic constituents from antheroporum pierrei. Journal of Natural Products, 74(4), 852-856.
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  PMID: 21452840;PMCID: PMC3371367;Abstract: Bioassay-guided fractionation of a solid tumor selective extract of the leaves and twigs of Antheroporum pierrei acquired from the U.S. National Cancer Institute extract repository afforded four new pyranoisoflavones, pierreiones A-D (1-4), together with rotenone (5), 12a-hydroxyrotenone (6), and tephrosin (7). The structures of all new compounds were determined on the basis of their spectroscopic data, and the absolute configuration of 1 was assigned with the help of 1H NMR analysis of its Mosher's ester derivatives. Compounds 1 and 5-7 accounted for the majority of the biological activity in terms of either cytotoxicity and/or selective toxicity to solid tumor cell lines. Pierreiones A (1) and B (2) demonstrated solid tumor selectivity with minimal cytotoxicity, while pierreione C (3) exhibited no activity. © 2011 The American Chemical Society and American Society of Pharmacognosy.
• Gao, S., Xu, Y., Valeriote, F. A., & Gunatilaka, A. A. (2011). Pierreiones A-D, solid tumor selective pyranoisoflavones and other cytotoxic constituents from Antheroporum pierrei. Journal of natural products, 74(4).
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  Bioassay-guided fractionation of a solid tumor selective extract of the leaves and twigs of Antheroporum pierrei acquired from the U.S. National Cancer Institute extract repository afforded four new pyranoisoflavones, pierreiones A-D (1-4), together with rotenone (5), 12a-hydroxyrotenone (6), and tephrosin (7). The structures of all new compounds were determined on the basis of their spectroscopic data, and the absolute configuration of 1 was assigned with the help of (1)H NMR analysis of its Mosher's ester derivatives. Compounds 1 and 5-7 accounted for the majority of the biological activity in terms of either cytotoxicity and/or selective toxicity to solid tumor cell lines. Pierreiones A (1) and B (2) demonstrated solid tumor selectivity with minimal cytotoxicity, while pierreione C (3) exhibited no activity.
• Gunatilaka, L. -., Liu, X., Qi, W., Cooke, L. S., Wijeratne, E. M., Marron, M. T., & Mahadevan, D. (2011). An analog of withaferin A activates the MAPK and glutathione stress pathways and inhibits pancreas cancer cell proloferation. Cancer Investigation, 29, 668-675.
• Gunatilaka, L. -., Xu, Y., Ramirez-Ahumada, M. d., & Valeriote, F. A. (2011). Solid rumor inhibitory and other constituents of Casimiroa tetrameria. Chinese Journal of Natural Medicines, 9(5), 334-337.
• Liu, X., Wenqing, Q. i., Cooke, L. S., Wijeratne, E. K., Xu, Y., Marron, M. T., Gunatilaka, A. L., & Mahadevan, D. (2011). An analog of withaferin a activates the MAPK and glutathione "stress" pathways and inhibits pancreatic cancer cell proliferation. Cancer Investigation, 29(10), 668-675.
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  PMID: 22085270;Abstract: Withaferin A (WA) (1) and two analogs [4-epi-withaferin A (2) and 4,27-diacetyl-4-epi-withaferin A (3)] were evaluated for antitumor activity in pancreatic cancer cells. IC50 for 1, 2, and 3 were 0.87, 0.45, and 0.29 μM (BxPC-3); 1.28, 1.53, and 0.52 μM (MIAPaCa-2); and 0.59, 2.25, and 0.56 μM (PANC-1), respectively. We chose WA analog 3 for functional studies with confirmatory RT-PCR and Western blotting. ANOVA identified 33 (MIAPaCa-2), 54 (PANC-1), and 48 (BxPC-3) gene expression changes. Fisher exact test demonstrated MAPK and glutathione pathways to be overexpressed with WA analog 3. WA analog 3 elicits a dose-and time-dependent apoptosis, activates MAPK and glutathione "stress" pathways, and inhibits proliferation. © 2011 Informa Healthcare USA, Inc.
• Wang, X., Bashyal, B. P., M., E., U'Ren, J. M., Liu, M. X., Gunatilaka, M. K., Arnold, A. E., & A., A. (2011). Smardaesidins -G, isopimarane and 20 nor-isopimarane diterpenoids from Smardaea sp., a fungal endophyte of the moss Ceratodon purpureus (1). Journal of Natural Products, 74(10), 2052-2061.
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  PMID: 21999655;PMCID: PMC3371368;Abstract: Five new isopimarane diterpenes, smardaesidins -E (1- 5) and two new 20-nor-isopimarane diterpenes, smardaesidins F (6) and G (7), together with sphaeropsidins A (8) and C-F (10-13) were isolated from an endophytic fungal strain, Smardaea sp. AZ0432, occurring in living photosynthetic tissue of the moss Ceratodon purpureus. Of these, smardaesidins B (2) and C (3) were obtained as an inseparable mixture of isomers. Chemical reduction of sphaeropsidin A (8) afforded sphaeropsidin B (9), whereas catalytic hydrogenation of 8 yielded 7-O-15,16-tetrahydrosphaeropsidin A (14) and its new derivative, 7-hydroxy-6-oxoisopimara-7-en-20-oic acid (15). The acetylation and diazomethane reaction of sphaeropsidin A (8) afforded two of its known derivatives, 6-O-acetylsphaeropsidin A (16) and 8,14-methylenesphaeropsidin A methyl ester (17), respectively. Methylation of 10 yielded sphaeropsidin C methyl ester (18). The planar structures and relative configurations of the new compounds 1-7 and 15 were elucidated using MS and 1D and 2D NMR experiments, while the absolute configurations of the stereocenters of 4 and 6-8 were assigned using a modified Mosher's ester method, CD spectra, and comparison of specific rotation data with literature values. Compounds 1-18 were evaluated for their potential anticancer activity using several cancer cell lines and cells derived from normal human primary fibroblasts. Of these, compounds 8, 11, and 16 showed significant cytotoxic activity. More importantly, sphaeropsidin A (8) showed cell-type selectivity in the cytotoxicity assay and inhibited migration of metastatic breast adenocarcinoma (MDA-MB-231) cells at subcytotoxic concentrations. © 2011 The American Chemical Society and American Society of Pharmacognosy.
• Wang, X., Bashyal, B. P., Wijeratne, E. M., U'Ren, J. M., Liu, M. X., Gunatilaka, M. K., Arnold, A. E., & Gunatilaka, A. A. (2011). Smardaesidins A-G, isopimarane and 20-nor-isopimarane diterpenoids from Smardaea sp., a fungal endophyte of the moss Ceratodon purpureus. Journal of natural products, 74(10).
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  Five new isopimarane diterpenes, smardaesidins A-E (1- 5) and two new 20-nor-isopimarane diterpenes, smardaesidins F (6) and G (7), together with sphaeropsidins A (8) and C-F (10-13) were isolated from an endophytic fungal strain, Smardaea sp. AZ0432, occurring in living photosynthetic tissue of the moss Ceratodon purpureus . Of these, smardaesidins B (2) and C (3) were obtained as an inseparable mixture of isomers. Chemical reduction of sphaeropsidin A (8) afforded sphaeropsidin B (9), whereas catalytic hydrogenation of 8 yielded 7-O-15,16-tetrahydrosphaeropsidin A (14) and its new derivative, 7-hydroxy-6-oxoisopimara-7-en-20-oic acid (15). The acetylation and diazomethane reaction of sphaeropsidin A (8) afforded two of its known derivatives, 6-O-acetylsphaeropsidin A (16) and 8,14-methylenesphaeropsidin A methyl ester (17), respectively. Methylation of 10 yielded sphaeropsidin C methyl ester (18). The planar structures and relative configurations of the new compounds 1-7 and 15 were elucidated using MS and 1D and 2D NMR experiments, while the absolute configurations of the stereocenters of 4 and 6-8 were assigned using a modified Mosher's ester method, CD spectra, and comparison of specific rotation data with literature values. Compounds 1-18 were evaluated for their potential anticancer activity using several cancer cell lines and cells derived from normal human primary fibroblasts. Of these, compounds 8, 11, and 16 showed significant cytotoxic activity. More importantly, sphaeropsidin A (8) showed cell-type selectivity in the cytotoxicity assay and inhibited migration of metastatic breast adenocarcinoma (MDA-MB-231) cells at subcytotoxic concentrations.
• Wijeratne, E. K., & Gunatilaka, A. L. (2011). Biomimetic conversion of (-)-fusoxypyridone and (-)-oxysporidinone to (-)-sambutoxin: Further evidence for the structure of the tricyclic pyridone alkaloid, (-)-fusoxypyridone. Bioorganic and Medicinal Chemistry Letters, 21(8), 2327-2329.
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  PMID: 21419624;PMCID: PMC3359017;Abstract: Biomimetic-type reactions of the tricyclic pyridone alkaloid, (-)-fusoxypyridone [(-)-4,6′-anhydrooxysporidinone] (1), recently encountered in an endophytic strain of Fusarium oxysporum, and (-)-oxysporidinone (2) afforded (-)-sambutoxin (3) and an analogue of 1, identified as (-)-1′(6′)-dehydro-4,6′-anhydrooxysporidinone (4), thus confirming the structure previously proposed for 1 and suggesting that 1-3 bear the same relative stereochemistry. Oxidation of 4 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) yielded a hitherto unknown sambutoxin analogue, (-)-4,2′-anhydrosambutoxin (5). © 2011 Elsevier Ltd. All rights reserved.
• Wijeratne, E. M., & Gunatilaka, A. A. (2011). Biomimetic conversion of (-)-fusoxypyridone and (-)-oxysporidinone to (-)-sambutoxin: further evidence for the structure of the tricyclic pyridone alkaloid, (-)-fusoxypyridone. Bioorganic & medicinal chemistry letters, 21(8).
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  Biomimetic-type reactions of the tricyclic pyridone alkaloid, (-)-fusoxypyridone [(-)-4,6'-anhydrooxysporidinone] (1), recently encountered in an endophytic strain of Fusarium oxysporum, and (-)-oxysporidinone (2) afforded (-)-sambutoxin (3) and an analogue of 1, identified as (-)-1'(6')-dehydro-4,6'-anhydrooxysporidinone (4), thus confirming the structure previously proposed for 1 and suggesting that 1-3 bear the same relative stereochemistry. Oxidation of 4 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) yielded a hitherto unknown sambutoxin analogue, (-)-4,2'-anhydrosambutoxin (5).
• Xu, Y., Gao, S., Bunting, D. P., & Gunatilaka, A. A. (2011). Unusual withanolides from aeroponically grown Withania somnifera. Phytochemistry, 72(6).
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  In an attempt to maximize production and the structural diversity of plant metabolites, the effect of growing the medicinal plant Withania somnifera under soil-less aeroponic conditions on its ability to produce withaferin A and withanolides was investigated. It resulted in the isolation and characterization of two compounds, 3α-(uracil-1-yl)-2,3-dihydrowithaferin A (1) and 3β-(adenin-9-yl)-2,3-dihydrowithaferin A (2), in addition to 10 known withanolides including 2,3-dihydrowithaferin A-3β-O-sulfate. 3β-O-Butyl-2,3-dihydrowithaferin A (3), presumably an artifact formed from withaferin A during the isolation process was also encountered. Reaction of withaferin A with uracil afforded 1 and its epimer, 3β-(uracil-1-yl)-2,3-dihydrowithaferin A (4). The structures of these compounds were elucidated on the basis of their high resolution mass and NMR spectroscopic data.
• Xu, Y., Gao, S., Bunting, D. P., & Gunatilaka, A. L. (2011). Unusual withanolides from aeroponically grown Withania somnifera. Phytochemistry, 72(6), 518-522.
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  PMID: 21315384;Abstract: In an attempt to maximize production and the structural diversity of plant metabolites, the effect of growing the medicinal plant Withania somnifera under soil-less aeroponic conditions on its ability to produce withaferin A and withanolides was investigated. It resulted in the isolation and characterization of two compounds, 3α-(uracil-1-yl)-2,3-dihydrowithaferin A (1) and 3β-(adenin-9-yl)-2,3-dihydrowithaferin A (2), in addition to 10 known withanolides including 2,3-dihydrowithaferin A-3β-O-sulfate. 3β-O-Butyl-2,3-dihydrowithaferin A (3), presumably an artifact formed from withaferin A during the isolation process was also encountered. Reaction of withaferin A with uracil afforded 1 and its epimer, 3β-(uracil-1-yl)-2,3- dihydrowithaferin A (4). The structures of these compounds were elucidated on the basis of their high resolution mass and NMR spectroscopic data. © 2011 Elsevier Ltd. All rights reserved.
• Xu, Y., del, M., Valeriote, F. A., & Gunatilaka, A. L. (2011). Solid tumor inhibitory and other constituents of Casimiroa tetrameria. Chinese Journal of Natural Medicines, 9(5), 334-337.
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  Abstract: Aim: To isolate and characterize solid tumor inhibitory and other constituents from a bioactive extract of Casimiroa tetrameria ((Rutaceae). Methods: A crude extract of C. tetrameria obtained from the US National Cancer Institute Natural Product Repository and found to exhibit selective toxicity to solid tumor cells was subjected bioactivity-guided fractionation involving solvent-solvent partitioning, gel filtration, and chromatography. The structures of all isolated compounds were elucidated by spectroscopic analysis (NMR and MS) and/or by comparison with the reported data. Compounds 1 and 4-9 were evaluated for their solid tumor selective cytotoxicity. Results: Nine metabolites, including a new furanocoumarin, 5-methoxy-8-(4'-acetoxy-3'-methylbut-2-enyloxy)-psoralen (1), and the previously known compounds 2-9 were encountered. Of these the flavonoid zapotin (6), and N-benzoyltyramide derivatives 7 and 8 were found to be the active constituents. Conclusion: Zapotin (6) is the most potent constituent of C. tetrameria with solid tumor selectivity. © 2011 China Pharmaceutical University.
• Bashyal, B. P., & A., A. (2010). Tricinonoic acid and tricindiol, two new irregular sesquiterpenes from an endophytic strain of Fusarium tricinctum. Natural Product Research, 24(4), 349-356.
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  PMID: 20221941;PMCID: PMC3105968;Abstract: Two new rare irregular sesquiterpenes, tricinonoic acid (1) and tricindiol (2), and the known furanopyrrolidones, NG-391 (3) and NG-393 (4), have been isolated from an EtOAc extract of Fusarium tricinctum, a fungus endophytic in the root tissue of the Sonoran desert plant, Rumex hymenosepalus. The structures of 1 and 2 were elucidated on the basis of their high-resolution mass, 1D and 2D NMR spectroscopic data. A possible biosynthetic route to 1 and 2 from farnesyl diphosphate is proposed. © 2010 Taylor & Francis.
• Lafayette, S. L., Collins, C., Zaas, A. K., Schell, W. A., Betancourt-Quiroz, M., Gunatilaka, A. L., Perfect, J. R., & Cowen, L. E. (2010). PKC signaling regulates drug resistance of the fungal pathogen candida albicans via circuitry comprised of mkc1, calcineurin, and hsp90. PLoS Pathogens, 6(8), 79-80.
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  PMID: 20865172;PMCID: PMC2928802;Abstract: Fungal pathogens exploit diverse mechanisms to survive exposure to antifungal drugs. This poses concern given the limited number of clinically useful antifungals and the growing population of immunocompromised individuals vulnerable to lifethreatening fungal infection. To identify molecules that abrogate resistance to the most widely deployed class of antifungals, the azoles, we conducted a screen of 1,280 pharmacologically active compounds. Three out of seven hits that abolished azole resistance of a resistant mutant of the model yeast Saccharomyces cerevisiae and a clinical isolate of the leading human fungal pathogen Candida albicans were inhibitors of protein kinase C (PKC), which regulates cell wall integrity during growth, morphogenesis, and response to cell wall stress. Pharmacological or genetic impairment of Pkc1 conferred hypersensitivity to multiple drugs that target synthesis of the key cell membrane sterol ergosterol, including azoles, allylamines, and morpholines. Pkc1 enabled survival of cell membrane stress at least in part via the mitogen activated protein kinase (MAPK) cascade in both species, though through distinct downstream effectors. Strikingly, inhibition of Pkc1 phenocopied inhibition of the molecular chaperone Hsp90 or its client protein calcineurin. PKC signaling was required for calcineurin activation in response to drug exposure in S. cerevisiae. In contrast, Pkc1 and calcineurin independently regulate drug resistance via a common target in C. albicans. We identified an additional level of regulatory control in the C. albicans circuitry linking PKC signaling, Hsp90, and calcineurin as genetic reduction of Hsp90 led to depletion of the terminal MAPK, Mkc1. Deletion of C. albicans PKC1 rendered fungistatic ergosterol biosynthesis inhibitors fungicidal and attenuated virulence in a murine model of systemic candidiasis. This work establishes a new role for PKC signaling in drug resistance, novel circuitry through which Hsp90 regulates drug resistance, and that targeting stress response signaling provides a promising strategy for treating life-threatening fungal infections. © 2010 LaFayette et al.
• M., E., Bashyal, B. P., Gunatilaka, M. K., Arnold, A. E., & A., A. (2010). Maximizing chemical diversity of fungal metabolites: Biogenetically related heptaketides of the endolichenic fungus Corynespora sp. (1). Journal of Natural Products, 73(6), 1156-1159.
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  PMID: 20521776;PMCID: PMC3372999;Abstract: In an attempt to explore the biosynthetic potential of the endolichenic fungus Corynespora sp. BA-10763, its metabolite profiles under several culture conditions were investigated. When cultured in potato dextrose agar, it produced three new heptaketides, 9-O-methylscytalol A (1), 7-desmethylherbarin (2), and 8-hydroxyherbarin (3), together with biogenetically related metabolites scytalol A (4), 8-O-methylfusarubin (5), scorpinone (6), and 8-O-methylbostrycoidin (7), which are new to this organism, and herbarin (8), a metabolite previously encountered in this fungal strain. The use of malt extract agar as the culture medium led to the isolation of 6, 8, 1-hydroxydehydroherbarin (9), and 1-methoxydehydroherbarin (10), which was found to be an artifact formed during the extraction of the culture medium with methanol. The structures of all new compounds were determined by interpretation of their spectroscopic data and chemical interconversions. © 2010 The American Chemical Society and American Society of Pharmacognosy.
• Messiano, G. B., M., E., M., L., & A., A. (2010). Microbial transformations of aryltetralone and aryltetralin lignans by Cunninghamella echinulata and Beauveria bassiana. Journal of Natural Products, 73(11), 1933-1937.
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  PMID: 20961092;Abstract: Microbiological transformation of the aryltetralone lignan (-)-8′-epi-aristoligone (1) with Cunninghamella echinulata ATCC 10028B afforded two known natural lignans, (-)-holostyligone (3) and (-)-arisantetralone (4). Incubation of the aryltetralin lignan (-)-isogalbulin (2), obtained by chemical transformation of 1, with C. echinulata ATCC 10028B afforded the known lignan aryltetralol (5) and seven new metabolites, (-)-8-hydroxyisogalbulin (6), (-)-7-methoxyisogalbulin (7), (-)-4′-O- demethyl-8-hydroxyisogalbulin (8), (-)-7-methoxy-8-hydroxyisogalbulin (9), (-)-4′-O-demethyl-7-methoxyisogalbulin (10), (-)-4′,5-O- didemethylcyclogalgravin (11), and (-)-4′-O-demethylcyclogalgravin (12). When 2 was subjected to biotransformation with Beauveria bassiana ATCC 7159, (-)-8-hydroxyisogalbulin (6) was the only isolable product. The structures of all new compounds were established by detailed analysis of their spectroscopic data. © 2010 The American Chemical Society and American Society of Pharmacognosy.
• Yanke, Y. u., Hamza, A., Zhang, T., Mancang, G. u., Zou, P., Newman, B., Yanyan, L. i., Gunatilaka, A. L., Zhan, C., & Sun, D. (2010). Withaferin A targets heat shock protein 90 in pancreatic cancer cells. Biochemical Pharmacology, 79(4), 542-551.
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  PMID: 19769945;PMCID: PMC2794909;Abstract: The purpose of this study is to investigate the efficacy and the mechanism of Hsp90 inhibition of Withaferin A (WA), a steroidal lactone occurring in Withania somnifera, in pancreatic cancer in vitro and in vivo. Withaferin A exhibited potent antiproliferative activity against pancreatic cancer cells in vitro (with IC50s of 1.24, 2.93 and 2.78 μM) in pancreatic cancer cell lines Panc-1, MiaPaCa2 and BxPc3, respectively. Annexin V staining showed that WA induced significant apoptosis in Panc-1 cells in a dose-dependent manner. Western blotting demonstrated that WA inhibited Hsp90 chaperone activity to induce degradation of Hsp90 client proteins (Akt, Cdk4 and glucocorticoid receptor), which was reversed by the proteasomal inhibitor, MG132. WA-biotin pull down assay of Hsp90 using Panc-1 cancer cell lysates and purified Hsp90 showed that WA-biotin binds to C-terminus of Hsp90 which was competitively blocked by unlabeled WA. Co-immunoprecipitation exhibited that WA (10 μM) disrupted Hsp90-Cdc37 complexes from 1 to 24 h post-treatment, while it neither blocked ATP binding to Hsp90, nor changed Hsp90-P23 association. WA (3, 6 mg/kg) inhibited tumor growth in pancreatic Panc-1 xenografts by 30% and 58%, respectively. These data demonstrate that Withaferin A binds Hsp90, inhibits Hsp90 chaperone activity through an ATP-independent mechanism, results in Hsp90 client protein degradation, and exhibits in vivo anticancer activity against pancreatic cancer.
• Zhan, J., M., E., & A., A. (2010). Structure determination of two new monocillin I derivatives. Natural Product Communications, 5(5), 801-804.
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  PMID: 20521550;Abstract: Biotransformation of monocillin I (1) by Beauveria bassiana ATCC 7159 was investigated. Two new derivatives 2 and 3 were isolated and identified on the basis of the spectroscopic data. Compounds 2 and 3 are synthesized by hydration at 10,11-double bond and hydrolysis of 14,15-epoxide, respectively. The R configuration of 11-OH in 2 was established by the modified 2-methoxy-2- trifluoromethylphenylacetic acid (MTPA) method. The conversion of 1 to 2 and 3 was reconstituted in an acid solution, indicating that the formation of 2 and 3 is an acid-catalyzed instead of an enzymatic process.
• A., A., Da, V., & Newman, D. J. (2009). Special issue in honor of professor david G. I. kingston. Journal of Natural Products, 72(3), 325-326.
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  PMID: 19243191;
• Yuquan, X. u., Orozco, R., Wijeratne, E. K., Espinosa-Artiles, P., Gunatilaka, A. L., Stock, S. P., & Molnár, I. (2009). Biosynthesis of the cyclooligomer depsipeptide bassianolide, an insecticidal virulence factor of Beauveria bassiana. Fungal Genetics and Biology, 46(5), 353-364.
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  PMID: 19285149;Abstract: Beauveria bassiana is a facultative entomopathogen with an extremely broad host range that is used as a commercial biopesticide for the control of insects of agricultural, veterinary and medical significance. B. bassiana produces bassianolide, a cyclooligomer depsipeptide secondary metabolite. We have cloned the bbBsls gene of B. bassiana encoding a nonribosomal peptide synthetase (NRPS). Targeted inactivation of the B. bassiana genomic copy of bbBsls abolished bassianolide production, but did not affect the biosynthesis of beauvericin, another cyclodepsipeptide produced by the strain. Comparative sequence analysis of the BbBSLS bassianolide synthetase revealed enzymatic domains for the iterative synthesis of an enzyme-bound dipeptidol monomer intermediate from d-2-hydroxyisovalerate and l-leucine. Further BbBSLS domains are predicted to catalyze the formation of the cyclic tetrameric ester bassianolide by recursive condensations of this monomer. Comparative infection assays against three selected insect hosts established bassianolide as a highly significant virulence factor of B. bassiana. © 2009 Elsevier Inc. All rights reserved.
• Yuquan, X. u., Wijeratne, E. K., Espinosa-Artiles, P., Gunatilaka, A. L., & Molnár, I. (2009). Combinatorial mutasynthesis of scrambled beauvericins, cyclooligomer depsipeptide cell migration inhibitors from Beauveria bassiana. ChemBioChem, 10(2), 345-354.
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  PMID: 19105175;Abstract: Fungal cyclooligomer depsipeptides such as beauvericin, bassianolide, and enniatins display antibiotic, antifungal, insecticidal, broad-spectrum cancer cell antiproliferative, and cell migration inhibitory activities. We have identified a gene encoding a novel enzyme, ketoisovalerate reductase (KIVR), which is the sole provider of D-hydroxyisovalerate (D-Hiv), a common precursor for cyclooligomer depsipeptide biosynthesis in Beauveria bassiana. KIVR and related hypothetical oxidoreductases encoded in fungal genomes are similar to ketopantoate reductases but not to D-hydroxycarboxylate dehydrogenases. We demonstrate that a KIVR knockout B. bassiana strain can be used for the efficient mutasynthesis of unnatural beauvericin congeners. Simultaneous feeding of precursor analogues enabled the combinatorial mutasynthesis of scrambled beauvericins, some assembled entirely from unnatural precursors. The effects of the introduced structural changes on the antiproliferative and cell migration inhibitory ACHTUNGTRENNUNGactivities of these analogues were evaluated. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
• Jacobsen, N. E., Wijeratne, E. K., Corsino, J., Furlan, M., da, V., & Gunatilaka, A. L. (2008). Biomimetic synthesis of xuxuarines Eα and Eβ: Structure revision of Rzedowskia bistriterpenoids. Bioorganic and Medicinal Chemistry, 16(4), 1884-1889.
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  PMID: 18055208;Abstract: Reaction of pristimerin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) resulted in a biomimetic-type coupling leading to xuxuarines Eα and Eβ and not the previously reported Rzedowskia bistriterpenoids I and II suggesting that the structures proposed for these natural products need revision. A product obtained in this reaction by an unusual Diels-Alder addition followed by retro-Diels-Alder-type elimination was characterized as pristimerin dicyanophenalenedione. Complete 1H, and 13C NMR spectral assignments of xuxuarines Eα and Eβ have been made by the application of 1D and 2D NMR techniques. © 2007 Elsevier Ltd. All rights reserved.
• M., E., Paranagama, P. A., Marron, M. T., Gunatilaka, M. K., Arnold, A. E., & A., A. (2008). Sesquiterpene quinones and related metabolites from Phyllosticta spinarum, a fungal strain endophytic in Platycladus orientalis of the Sonoran desert. Journal of Natural Products, 71(2), 218-222.
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  PMID: 18247573;Abstract: Five new metabolites, (+)-(5S,10S)-4′-hydroxymethylcyclozonarone (1), 3-ketotauranin (3), 3α-hydroxytauranin (4), 12-hydroxytauranin (5), and phyllospinarone (6), together with tauranin (2), were isolated from Phyllosticta spinarum, a fungal strain endophytic in Platycladus orientalis. The structures of the new compounds were determined on the basis of their 1D and 2D NMR spectroscopic data and chemical interconversions. All compounds were evaluated for inhibition of cell proliferation in a panel of five cancer cell lines, and only tauranin (2) showed activity. When tested in a flow cytometry-based assay, tauranin induced apoptosis in PC-3M and NIH 3T3 cell lines. © 2008 American Chemical Society and American Society of Pharmacognosy.
• Wang, S., Yuquan, X. u., Maine, E. A., Wijeratne, E. K., Espinosa-Artiles, P., Gunatilaka, A. L., & Molnár, I. (2008). Functional Characterization of the Biosynthesis of Radicicol, an Hsp90 Inhibitor Resorcylic Acid Lactone from Chaetomium chiversii. Chemistry and Biology, 15(12), 1328-1338.
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  PMID: 19101477;Abstract: Fungal polyketides with the resorcylic acid lactone (RAL) scaffold are of interest for growth stimulation, the treatment of cancer, and neurodegenerative diseases. The RAL radicicol is a nanomolar inhibitor of the chaperone Hsp90, whose repression leads to a combinatorial blockade of cancer-causing pathways. Clustered genes for radicicol biosynthesis were identified and functionally characterized from the endophytic fungus Chaetomium chiversii, and compared to recently described RAL biosynthetic gene clusters. Radicicol production is abolished upon targeted inactivation of a putative cluster-specific regulator, or either of the two polyketide synthases that are predicted to collectively synthesize the radicicol polyketide core. Genomic evidence supports the existence of flavin-dependent halogenases in fungi: inactivation of such a putative halogenase from the C. chiversii radicicol locus yields dechloro-radicicol (monocillin I). Inactivation of a cytochrome P450 epoxidase furnishes pochonin D, a deepoxy-dihydro radicicol analog. © 2008 Elsevier Ltd. All rights reserved.
• Yuquan, X. u., Orozco, R., Wijeratne, E. K., Gunatilaka, A. L., Stock, S. P., & Molnár, I. (2008). Biosynthesis of the Cyclooligomer Depsipeptide Beauvericin, a Virulence Factor of the Entomopathogenic Fungus Beauveria bassiana. Chemistry and Biology, 15(9), 898-907.
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  PMID: 18804027;Abstract: Beauvericin, a cyclohexadepsipeptide ionophore from the entomopathogen Beauveria bassiana, shows antibiotic, antifungal, insecticidal, and cancer cell antiproliferative and antihaptotactic (cell motility inhibitory) activity in vitro. The bbBeas gene encoding the BbBEAS nonribosomal peptide synthetase was isolated from B. bassiana and confirmed to be responsible for beauvericin biosynthesis by targeted disruption. BbBEAS utilizes D-2-hydroxyisovalerate (D-Hiv) and L-phenylalanine (Phe) for the iterative synthesis of a predicted N-methyl-dipeptidol intermediate, and forms the cyclic trimeric ester beauvericin from this intermediate in an unusual recursive process. Heterologous expression of the bbBeas gene in Escherichia coli to produce the 3189 amino acid, 351.9 kDa BbBEAS enzyme provided a strain proficient in beauvericin biosynthesis. Comparative infection assays with a BbBEAS knockout B. bassiana strain against three insect hosts revealed that beauvericin plays a highly significant but not indispensable role in virulence. © 2008 Elsevier Ltd. All rights reserved.
• Zhan, J., & Gunatilaka, A. L. (2008). Microbial metabolism of 1-aminoanthracene by Beauveria bassiana. Bioorganic and Medicinal Chemistry, 16(9), 5085-5089.
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  PMID: 18378148;Abstract: The carcinogen and mutagen, 1-aminoanthracene, was efficiently metabolized by the fungal strain Beauveria bassiana ATCC 7159 to yield three new metabolites identified as 1-acetamido-5-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthracene, 1-acetamido-8-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthraquinone, and 1-acetamido-6-[(4′-O-methyl-β-d-glucopyranosyl)oxy]anthraquinone, together with 1-acetamidoanthracene and 1-acetamidoanthraquinone. Formation of these metabolites suggests that the metabolic pathways of 1-aminoanthracene in B. bassiana ATCC 7159 involve acetylation, oxidation, hydroxylation, and O-methylglucosylation. © 2008.
• Carbonezi, C. A., Hamerski, L., A., A., Cavalheiro, A., Castro-Gamboa, I., Helena, D., Furlan, M., Claudia, M., Lopes, M. N., & Da, V. (2007). Bioactive flavone dimers from Ouratea multiflora (Ochnaceae). Brazilian Journal of Pharmacognosy, 17(3), 319-324.
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  Abstract: Chromatographic fractionation of the organic extract from leaves of Ouratea multiflora afforded the flavone dimers heveaflavone, amentoflavone-7′, 4‴-dimethyl eter, podocarpusflavone-A and amentoflavone. Their structures were elucidated from spectral data, including 2D-NMR experiments of the natural substances. Biological activities of all isolates were evaluated, using antimicrobial assay against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, cytotoxicity assay against mouse lymphoma (L5178) and KB cell lines, TLC screening for acetylcholinesterase inhibitors and antioxidant activity measured by DPPH test.
• McLellan, C. A., Turbyville, T. J., Wijeratne, E. K., Kerschen, A., Vierling, E., Queitsch, C., Whitesell, L., & Gunatilaka, A. L. (2007). A rhizosphere fungus enhances Arabidopsis thermotolerance through production of an HSP90 inhibitor. Plant Physiology, 145(1), 174-182.
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  PMID: 17631526;PMCID: PMC1976574;Abstract: The molecular chaperone HEAT SHOCK PROTEIN90 (HSP90) is essential for the maturation of key regulatory proteins in eukaryotes and for the response to temperature stress. Earlier, we have reported that fungi living in association with plants of the Sonoran desert produce small molecule inhibitors of mammalian HSP90. Here, we address whether elaboration of the HSP90 inhibitor monocillin I (MON) by the rhizosphere fungus Paraphaeosphaeria quadriseptata affects plant HSP90 and plant environmental responsiveness. We demonstrate that MON binds Arabidopsis (Arabidopsis thaliana) HSP90 and can inhibit the function of HSP90 in lysates of wheat (Triticum aestivum) germ. MON treatment of Arabidopsis seedlings induced HSP101 and HSP70, conserved components of the stress response. Application of MON, or growth in the presence of MON, allowed Arabidopsis wild type but not AtHSP101 knockout mutant seedlings to survive otherwise lethal temperature stress. Finally, cocultivation of P. quadriseptata with Arabidopsis enhanced plant heat stress tolerance. These data demonstrate that HSP90-inhibitory compounds produced by fungi can influence plant growth and responses to the environment. © 2007 American Society of Plant Biologists.
• Paranagama, P. A., M., E., & A., A. (2007). Uncovering biosynthetic potential of plant-associated fungi: Effect of culture conditions on metabolite production by Paraphaeosphaeria quadriseptata and Chaetomium chiversii. Journal of Natural Products, 70(12), 1939-1945.
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  PMID: 18052326;Abstract: In an attempt to uncover the biosynthetic potential of plant-associated fungi, the effect of culture conditions on metabolite production by Paraphaeosphaeria quadriseptata and Chaetomium chiversii was investigated. These studies indicated that the production of the major metabolites by P. quadriseptata differ when the water used to make the media was changed from tap water to distilled water. It resulted in the isolation of six new secondary metabolites, cytosporones F-I (1-4), quadriseptin A (5), and 5′-hydroxymonocillin III (6) together with monocillin III (7), a metabolite new to P. quadriseptata, in addition to monocillin I (8), a previously known metabolite from this organism. Aposphaerin B (9) encountered was suspected to be an artifact originating from cytosporone F (1). Incorporation of heavy metal ions to P. quadriseptata culture medium induced production of monocillin I (8) by this fungus. Cultivation of C. chiversii in liquid medium resulted in the isolation of chaetochromin A (12) as the major metabolite instead of radicicol (10), the major constituent of this organism when grown in a solid medium. Compounds 1-7 and 12 were evaluated for their potential to inhibit Hsp90 and antiproliferative activity toward the cancer cell lines NCI-H460, MCF-7, and SF-268. Only compounds 6, 7, and 8 exhibited significant activity in both assays. © 2007 American Chemical Society and American Society of Pharmacognosy.
• Paranagama, P. A., M., E., Burns, A. M., Marron, M. T., Gunatilaka, M. K., Arnold, A. E., & A., A. (2007). Heptaketides from Corynespora sp. inhabiting the cavern beard lichen, Usnea cavernosa: First report of metabolites of an endolichenic fungus. Journal of Natural Products, 70(11), 1700-1705.
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  PMID: 17988097;Abstract: Two new heptaketides, corynesporol (1) and 1-hydroxydehydroherbarin (2), along with herbarin (3) were isolated from an endolichenic fungal strain, Corynespora sp. BA-10763, occurring in the cavern beard lichen Usnea cavernosa. The structures of 1-3 were elucidated from their spectroscopic data. Aerial oxidation of corynesporol (1) yielded herbarin (3). Acetylation of 1 afforded the naphthalene derivative 4, whereas acetylation of 3 gave the corresponding naphthoquinone 6 and dehydroherbarin (5). All compounds were evaluated for their cytotoxicity and ability to inhibit migration of human metastatic breast and prostate cancer cell lines MDA-MB-231 and PC-3M, respectively. Dehydroherbarin (5) inhibited migration of both cell lines at concentrations not toxic to these cell lines. This is the first report of metabolites from an endolichenic fungus. © 2007 American Chemical Society and American Society of Pharmacognosy.
• Xu, Y., McLaughlin, S. P., & A., A. (2007). Sorbifolivaltrates A-D, diene valepotriates from Valeriana sorbifolia. Journal of Natural Products, 70(12), 2045-2048.
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  PMID: 18052324;Abstract: Four new diene valepotriates, sorbifolivaltrates A-D (1-4), and the known compounds isovaltrate (5), valtrate (6), seneciovaltrate (7), valtrate hydrine B3 (8), and valtrate hydrine B7 (9), have been isolated by bioassay-guided fractionation of the cytotoxic hexanes and methyl ethyl ketone crude extracts of the aerial parts of Valeriana sorbifolia occurring in the Sonoran desert. The structures of 1-4 were determined on the basis of their high-resolution mass spectrometric and NMR spectroscopic data. All compounds exhibited weak to moderate cytotoxicity against the human metastatic prostate cancer cell line, PC-3M. © 2007 American Chemical Society and American Society of Pharmacognosy.
• Yuquan, X. u., Zhan, J., M., E., Burns, A. M., A., A., & Molnár, I. (2007). Cytotoxic and antihaptotactic beauvericin analogues from precursor-directed biosynthesis with the insect pathogen Beauveria bassiana ATCC 7159. Journal of Natural Products, 70(9), 1467-1471.
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  PMID: 17803266;Abstract: Precursor-directed biosynthesis was used to produce analogues of the cyclic depsipeptide mycotoxin beauvericin (1) using the filamentous fungus Beauveria bassiana ATCC 7159. Feeding 30 analogues of D-2-hydroxyisovalerate and L-phenylalanine, the natural 2-hydroxycarboxylic acid and amino acid precursors of beauvericin, led to the biosynthesis of novel beauvericins. Six of these were isolated and characterized, and their cytotoxicity and directional cell migration (haptotaxis) inhibitory activity against the metastatic prostate cancer cell line PC-3M were evaluated. Replacement of one, two, or all three of the D-2-hydroxyisovalerate constituents in beauvericin (1) with 2-hydroxybutyrate moieties (beauvericins G1-3, compounds 2-4) caused a parallel decline of cell migration inhibitory activity and cytotoxicity, suggesting a requirement for a branched side chain for both of these biological activities at the corresponding positions of beauvericins. Replacement of one, two, or all three N-methyl-L-phenylalanine residues of beauvericin with N-methyl-L-3-fluorophenylalanine moieties (beauvericins H1-3, compounds 5-7) increased cytotoxicity without affecting antihaptotactic activity. © 2007 American Chemical Society and American Society of Pharmacognosy.
• Zhan, J., Burns, A. M., Liu, M. X., Faeth, S. H., & A., A. (2007). Search for cell motility and angiogenesis inhibitors with potential anticancer activity: Beauvericin and other constituents of two endophytic strains of Fusarium oxysporum. Journal of Natural Products, 70(2), 227-232.
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  PMID: 17286429;PMCID: PMC3361905;Abstract: Wound-healing assay-guided fractionation of an EtOAc extract of the fungal strain Fusarium oxysporum EPH2RAA endophytic in Ephedra fasciculata afforded beauvericin (1), (-)-oxysporidinone (2), and two new N-methyl-2-pyridones, (-)-4,6′-anhydrooxysporidinone (3) and (-)-6-deoxyoxysporidinone (4). Beauvericin (1) inhibited migration of the metastatic prostate cancer (PC-3M) and breast cancer (MDA-MB-231) cells and showed antiangiogenic activity in HUVEC-2 cells at sublethal concentrations. Cytotoxicity-guided fractionation of an EtOAc extract of F. oxysporum strain CECIS occurring in Cylindropuntia echinocarpus afforded rhodolamprometrin (5), bikaverin (6), and the new natural product 6-deoxybikaverin (7). All compounds were evaluated for cytotoxicity in a panel of four sentinel cancer cell lines, NCI-H460 (non-small-cell lung), MIA Pa Ca-2 (pancreatic), MCF-7 (breast), and SF-268 (CNS glioma), and only beauvericin (1) and bikaverin (6) were active, with 1 and 6 showing selective toxicity toward NCI-H460 and MIA Pa Ca-2, respectively. Interestingly, 6-deoxybikaverin (7) was completely devoid of activity, suggesting the requirement of the C-6 hydroxy group of bikaverin for its cytotoxic activity. © 2007 American Chemical Society and American Society of Pharmacognosy.
• Zhan, J., Kamal, G., Wijeratne, E. K., & Gunatilaka, A. L. (2007). Asperpyrone D and other metabolites of the plant-associated fungal strain Aspergillus tubingensis. Phytochemistry, 68(3), 368-372.
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  PMID: 17150233;PMCID: PMC3361907;Abstract: Bioactivity-guided fractionation of a cytotoxic extract of Aspergillus tubingensis, a fungal strain occurring in the rhizosphere of the Sonoran desert plant, Fallugia paradoxa, afforded a dimeric naphtho-γ-pyrone asperpyrone D, nine known naphtho-γ-pyrones, funalenone, and the cytotoxic cyclic penta-peptide, malformin A1. © 2006 Elsevier Ltd. All rights reserved.
• A., A. (2006). Natural products from plant-associated microorganisms: Distribution, structural diversity, bioactivity, and implications of their occurrence. Journal of Natural Products, 69(3), 509-526.
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  PMID: 16562864;PMCID: PMC3362121;Abstract: A growing body of evidence suggests that plant-associated microorganisms, especially endophytic and rhizosphere bacteria and fungi, represent a huge and largely untapped resource of natural products with chemical structures that have been optimized by evolution for biological and ecological relevance. A diverse array of bioactive small molecule natural products has been encountered in these microorganisms. The structures of over 230 metabolites isolated and characterized from over 70 plant-associated microbial strains during the past four years are presented with information on their hosts, culture conditions, and biological activities. Some significant biological and ecological implications of their occurrence are also reviewed. © 2006 American Chemical Society and American Society of Pharmacognosy.
• Bashyal, B. P., McLaughlin, S. P., & A., A. (2006). Zinagrandinolides A-C, cytotoxic δ-elemanolide-type sesquiterpene lactones from Zinnia grandiflora. Journal of Natural Products, 69(12), 1820-1822.
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  PMID: 17190470;Abstract: Three new δ-elemanolide-type sesquiterpene lactones, zinagrandinolides A-C (1-3), and the known δ-elemanolide 4 have been isolated by a bioassay-guided fractionation of a cytotoxic hexane extract of the aerial parts of Zinnia grandiflora. The structures of 1-3 were determined on the basis of high-resolution mass and NMR data. All compounds exhibited strong cytotoxicity against the cancer cell lines NCI-H460, MCF-7, SF-268, and MIA Pa Ca-2 and the normal human fibroblast cell type WI-38, but none showed significant selectivity. © 2006 American Chemical Society and American Society of Pharmacognosy.
• Falsey, R. R., Marron, M. T., M., G., Shirahatti, N., Mahadevan, D., A., A., & Whitesell, L. (2006). Actin microfilament aggregation induced by withaferin A is mediated by annexin II. Nature Chemical Biology, 2(1), 33-38.
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  PMID: 16408090;Abstract: The actin cytoskeleton supports diverse cellular processes such as endocytosis, oriented growth, adhesion and migration1. The dynamic nature of the cytoskeleton, however, has made it difficult to define the roles of the many accessory molecules that modulate actin organization, especially the multifunctional adapter protein annexin II (refs. 2,3). We now report that the compound withaferin A (1) can alter cytoskeletal architecture in a previously unknown manner by covalently binding annexin II and stimulating its basal F-actin cross-linking activity. Drug-mediated disruption of F-actin organization is dependent on annexin II expression by cells and markedly limits their migratory and invasive capabilities at subcytotoxic concentrations. Given the extensive ethnobotanical history of withaferin-containing plant preparations in the treatment of cancer and inflammatory and neurological disorders, we suggest that annexin II represents a feasible, previously unexploited target for therapeutic intervention by small-molecule drugs4. © 2005 Nature Publishing Group.
• M., E., Paranagama, P. A., & A., A. (2006). Five new isocoumarins from Sonoran desert plant-associated fungal strains Paraphaeosphaeria quadriseptata and Chaetomium chiversii. Tetrahedron, 62(36), 8439-8446.
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  Abstract: Five new isocoumarins, paraphaeosphaerins A-C and chaetochiversins A and B, biogenetically related to monocillin I and radicicol, have been isolated from solid agar cultures of Paraphaeosphaeria quadriseptata and Chaetomium chiversii, two fungal strains living in association with the Sonoran desert plants, Opuntia leptocaulis and Ephedra fasciculata, respectively. A new chroman-4-one, aposphaerin C, was also isolated from P. quadriseptata. Their structures and stereochemistry were elucidated using a combination of 1H and 13C homo- and hetero-nuclear 2D NMR techniques, 1H NMR analysis of Mosher's esters, and chemical correlations. © 2006 Elsevier Ltd. All rights reserved.
• Subramanian, B., Nakeff, A., Tenney, K., Crews, P., Gunatilaka, L., & Valeriote, F. (2006). A new paradigm for the development of anticancer agents from natural products. Journal of Experimental Therapeutics and Oncology, 5(3), 195-204.
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  PMID: 16528970;PMCID: PMC1693669;Abstract: A novel pharmacology paradigm has been developed which quickly and efficiently moves prospective anticancer drugs from the discovery phase through pharmacology testing and into therapeutic trial assessment. Following discovery, the drug is first assessed in a clonogenic assay which determines the cytotoxic effect of different concentrations of the drug at 3 different exposure durations: 2h, 24h and continuous (168 h). Second, pharmacokinetic information is obtained in both plasma and tumor for the drug administered at the maximum tolerated dose given intravenously. The first study defines the time-concentration profile required to obtain a specific cell survival for the tumor cells; the second study determines the concentration-time profile that can be obtained in both plasma and tumor at the maximum tolerated dose of the drug. The integration of this information determines whether a successful therapeutic trial is possible. Only when a drug shows therapeutic efficacy is a proteomics-based mechanism of action study initiated. Two drugs have been assessed in this paradigm: salicortin and fascaplysin A. © 2006 Old City Publishing, Inc.
• Turbyville, T. J., M., E., Liu, M. X., Burns, A. M., Seliga, C. J., Luevano, L. A., David, C. L., Faeth, S. H., Whitesell, L., & A., A. (2006). Search for Hsp90 inhibitors with potential anticancer activity: Isolation and SAR studies of radicicol and monocillin I from two plant-associated fungi of the Sonoran desert. Journal of Natural Products, 69(2), 178-184.
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  PMID: 16499313;PMCID: PMC1876775;Abstract: In an effort to discover small molecule inhibitors of Hsp90, we have screened over 500 EtOAc extracts of Sonoran desert plant-associated fungi using a two-stage strategy consisting of a primary cell-based heat shock induction assay (HSIA) followed by a secondary biochemical luciferase refolding assay (LRA). Bioassay-guided fractionation of extracts active in these assays derived from Chaetomium chiversii and Paraphaeosphaeria quadriseptata furnished the Hsp90 inhibitors radicicol (1) and monocillin I (2), respectively. In SAR studies, 1, 2, and their analogues, 3-16, were evaluated in these assays, and the antiproliferative activity of compounds active in both assays was determined using the breast cancer cell line MCF-7. Radicicol and monocillin I were also evaluated in a solid-phase competition assay for their ability to bind Hsp90 and to deplete cellular levels of two known Hsp90 client proteins with relevance to breast cancer, estrogen receptor (ER), and the type 1 insulin-like growth factor receptor (IGF-IR). Some inferences on SAR were made considering the crystal structure of the N-terminus of yeast Hsp90 bound to 1 and the observed biological activities of 1-16. Isolation of radicicol and monocillin I in this study provides evidence that we have developed an effective strategy for discovering natural product-based Hsp90 inhibitors with potential anticancer activity. © 2006 American Chemical Society and American Society of Pharmacognosy.
• Vieira, H. S., Takahashi, J. A., A., A., & Amélia, M. (2006). ¹H and ¹³C NMR signal assignments of a novel Baeyer-Villiger originated diterpene lactone. Magnetic Resonance in Chemistry, 44(2), 146-150.
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  PMID: 16358289;Abstract: A highly rearranged novel dilactone was the single product isolated from Baeyer-Villiger oxidation of a norketone prepared from grandiflorenic acid, a natural kaurane diterpene. The complete 1H and 13C NMR assignment is presented for this novel compound that showed discrete in vitro antibacterial activity. Copyright © 2005 John Wiley & Sons, Ltd.
• Wijeratne, E. K., Liu, M. X., Kantipudi, N. B., Brochini, C. B., Gunatilaka, A. L., & Canfield, L. M. (2006). Synthesis and preliminary biological evaluation of β-carotene and retinoic acid oxidation products. Bioorganic and Medicinal Chemistry, 14(23), 7875-7879.
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  PMID: 16908162;Abstract: Synthesis of the β-carotene oxidation product, 2,3-dihydro-5,8-endoperoxy-β-apo-carotene-13-one (1) was achieved in six steps starting from β-ionone. Photo-oxygenation of all trans-retinoic acid (8) and 13-cis-retinoic acid (9) produced a mixture of 5S*,8S*-epidioxy-5,8-dihydroretinoic acid (10) and 13-cis-5S*,8S*-epidioxy-5,8-dihydroretinoic acid (11). Methylation of the crude photo-oxygenation mixture afforded the corresponding methyl esters 12 and 13, respectively, both of which underwent ready aerial oxidation yielding hitherto unknown oxidation products of retinoic acid identified as methyl 5S*,8S*-epidioxy-9,10β-epoxy-5,8,9,10-tetrahydroretinoate (14) and methyl 13-cis-5S*,8S*-epidioxy-9,10β-epoxy-5,8,9,10-tetrahydroretinoate (15). Evaluation of 1, all trans-retinoic acid (8), 13-cis-retinoic acid (9), and the photo-oxygenation products 10-15 in a panel of five cancer cell lines showed 1 to be inactive and that 11 is significantly cytotoxic compared with the other retinoic acid analogs suggesting the requirement of the carboxylic acid moiety and the cis-geometry of the 13(14) double bond for cytotoxic activity. © 2006 Elsevier Ltd. All rights reserved.
• Wijeratne, E. K., Turbyville, T. J., Fritz, A., Whitesell, L., & Gunatilaka, A. L. (2006). A new dihydroxanthenone from a plant-associated strain of the fungus Chaetomium globosum demonstrates anticancer activity. Bioorganic and Medicinal Chemistry, 14(23), 7917-7923.
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  PMID: 16904330;Abstract: Bioassay-guided fractionation of a cytotoxic EtOAc extract of the fungal strain, Chaetomium globosum, inhabiting the rhizosphere of the Christmas cactus, Opuntia leptocaulis, of the Sonoran desert afforded a new dihydroxanthenone, globosuxanthone A (1), a new tetrahydroxanthenone, globosuxanthone B (2), two new xanthones, globosuxanthone C (3) and D (4), 2-hydroxyvertixanthone (5), and two known anthraquinones (6 and 7). The structures of the new compounds 1-4 were elucidated by NMR and MS techniques, and the relative stereochemistry of 1 was determined by X-ray crystallographic analysis. Of the compounds encountered, 1 was found to exhibit strong cytotoxicity against a panel of seven human solid tumor cell lines, disrupt the cell cycle leading to the accumulation of cells in either G2/M or S phase, and induce classic signs of apoptosis. © 2006 Elsevier Ltd. All rights reserved.
• Zhan, J., & Gunatilaka, A. L. (2006). Microbial transformation of amino- and hydroxyanthraquinones by Beauveria bassiana ATCC 7159. Journal of Natural Products, 69(10), 1525-1527.
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  PMID: 17067178;Abstract: Microbial biotransformation of four amino- and hydroxyanthraquinones catalyzed by Beauveria bassiana ATCC 7159 has been studied. Incubation of 1,2-diaminoanthraquinone (1) with B. bassiana ATCC 7159 afforded 1-amino-2-(4′-O-methyl-2β-N-D-glucopyranosylamino)anthraquinone (5) in a hitherto unprecedented biotransformation involving N-glycosylation of an amine. Biotransformation of 1-aminoanthraquinone (2) yielded 1-amino-2-(4′-O-methyl-2β-O-D-glucopyranosyloxy)anthraquinone (6) as a result of microbial hydroxylation of C-2 followed by 4′-O-methyl- glucosylation of the newly introduced hydroxyl group. 1,8-Dihydroxyanthraquinone (3) and 1,2-dihydroxyanthraquinone (4) afforded 8-hydroxy-1-(4′-O-methyl- 1β-O-D-glucopyranosyloxy)anthraquinone (7) and 1-hydroxy-2-(4′-O- methyl-2β-O-D-glucopyranosyloxy)anthraquinone (8), respectively, resulting from 4′-O-methyl-glucosylation of the existing hydroxyl groups of the substrates. The efficiency of these conversions suggests that microbial biotransformation reactions offer an attractive alternative to chemical 4′-O-methyl-glucosylation of amino- and hydroxyanthraquinones. © 2006 American Chemical Society and American Society of Pharmacognosy.
• Zhan, J., & Gunatilaka, A. L. (2006). Selective 4′-O-methylglycosylation of the pentahydroxy-flavonoid quercetin by Beauveria bassiana ATCC 7159. Biocatalysis and Biotransformation, 24(5), 396-399.
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  Abstract: Biotransformation of the pentahydroxy-flavonoid natural product, quercetin, by Beauveria bassiana ATCC 7159 afforded a new derivative, quercetin-4′-O-methyl-7-β-D-glucopyranoside, in 87% isolated yield suggesting that glucosylation of the substrate occurred with high selectivity at C-7-OH out of the five hydroxyl groups. Most of the product was isolated from the mycelium and the filtrate of the culture medium did not show any catalytic activity. The mycelium is capable of performing this biotransformation when suspended in buffers of pH 2.1 and 7.2, suggesting that intracellular enzymes are involved and that they are active at a wide range of extracellular pH.
• Bashyal, B. P., Wijeratne, E. K., Faeth, S. H., & Gunatilaka, A. L. (2005). Globosumones A-C, cytotoxic orsellinic acid esters from the sonoran desert endophytic fungus Chaetomium globosum. Journal of Natural Products, 68(5), 724-728.
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  PMID: 15921417;Abstract: Three new esters of orsellinic acid, globosumones A-C (1-3), and three known compounds, orsellinic acid (4), orcinol, and trichodion (5), were isolated from Chaetomium globosum endophytic on Ephedra fasciculata (Mormon tea). The structures of the new compounds 1-3 were established spectroscopically, which included 2D NMK experiments and 1H NMK studies on Mosher's ester derivatives. All compounds were evaluated for inhibition of cell proliferation in a panel of four cancer cell lines, NCI-H460 (non-small cell lung cancer), MCF-7 (breast cancer), SF-268 (CNS glioma), and MIA Pa Ca-2 (pancreatic carcinoma), and normal human fibroblast cells (WI-38). Only globosumones A (1) and B (2) were found to be moderately active. © 2005 American Chemical Society and American Society of Pharmacognosy.
• Hsieh, T., Wijeratne, E. K., Liang, J., Gunatilaka, A. L., & Wu, J. M. (2005). Differential control of growth, cell cycle progression, and expression of NF-κB in human breast cancer cells MCF-7, MCF-10A, and MDA-MB-231 by ponicidin and oridonin, diterpenoids from the Chinese herb Rabdosia rubescens. Biochemical and Biophysical Research Communications, 337(1), 224-231.
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  PMID: 16176802;Abstract: Ponicidin and oridonin are novel diterpenoids isolated from Rabdosia rubescens. We tested their effects in MCF-7 and MDA-MB-231 cells, as representing low and high invasive breast carcinoma, with normal MCF-10A cells. Clonogenicity and proliferation in MCF-7 cells were inhibited more significantly by ponicidin than oridonin, while the reverse was observed in MCF-10A cells. Ponicidin and oridonin induced S/G2M arrest and G1/S block in MCF-7 cells. In MCF-10A cells treated with either diterpenoid, induction of apoptosis was observed. Moreover, oridonin almost completely blocked MCF-10A progression from S to G2/M phase; in contrast, ponicidin-treated MCF-10A cells showed no discernable changes in cell cycle phase distribution. Neither diterpenoid affected growth of MDA-MB-231 cells, at the dose range effective for MCF-7 or MCF-10A cells. Ponicidin-treated MCF-7 cells expressed reduced levels of cyclin B1, cdc2, transcription factor E2F, and Rb including phosphorylation at S780. Less pronounced effects were found in cells treated with oridonin. Neither compound altered cyclin D1 and cdk4 in MCF-7 cells. In MCF-10A cells, oridonin was more active than ponicidin in inhibiting the expression of cyclin B1, cdc2, S780-phosphorylated Rb, and E2F. To further investigate induction of apoptosis in MCF-10A cells, we measured changes in NF-κB. Decreases in p65 or p50 forms of NF-κB and its upstream regulator I-κB were found in oridonin-treated MCF-10A and not MCF-7 cells. Taken together, these results provide a mechanistic framework for the cellular effects of ponicidin and oridonin in different stage breast cancer cells. © 2005 Elsevier Inc. All rights reserved.
• Turbyville, T. J., Wijeratne, E. K., Whitesell, L., & Gunatilaka, A. L. (2005). The anticancer activity of the fungal metabolite terrecyclic acid A is associated with modulation of multiple cellular stress response pathways. Molecular Cancer Therapeutics, 4(10), 1569-1576.
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  PMID: 16227407;Abstract: Tumors are dependent on cellular stress responses, in particular the heat shock response, for survival in their hypoxic, acidotic, and nutrient-deprived microenvironments. Using cell-based reporter assays, we have identified terrecyclic acid A (TCA) from Aspergillus terreus, a fungus inhabiting the rhizosphere of Opuntia versicolor of the Sonoran desert, as a small-molecule inducer of the heat shock response that shows anticancer activity. Further characterization suggested that TCA also affects oxidative and inflammatory cellular stress response pathways. The presence of an α-methylene ketone moiety suggested that TCA may form adducts with sulfhydryl groups of proteins. Reaction with labile intracellular cysteines was supported by our finding that the glutathione precursor N-acetyl-cysteine protected tumor cells from the cytotoxic effects of TCA whereas the glutathione-depleting agent buthionine sulfoximine enhanced its activity. Related sesquiterpenes have been shown to increase levels of reactive oxygen species (ROS) and to inhibit nuclear factor κB (NF-κB) transcriptional activity. To assess whether TCA could have similar activities, we used a ROS-sensitive dye and flow cytometry to show that TCA does indeed increase ROS levels in 3LL cells. When tested in cells carrying NF-κB reporter constructs, TCA also exhibited concentration-dependent inhibition of cytokine-induced NF-κB transcriptional activity. These findings suggest that TCA modulates multiple stress pathways - the oxidative, heat shock, and inflammatory responses - in tumor cells that promote their survival. Small-molecule natural products such as TCA may serve as useful probes for understanding the relationships between these pathways, potentially providing leads for the design of novel and effective anti-cancer drugs. Copyright © 2005 American Association for Cancer Research.
• Zhan, J., & A., A. (2005). Microbial transformation of curvularin. Journal of Natural Products, 68(8), 1271-1273.
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  PMID: 16124776;Abstract: The microbiological transformation of curvularin (1) with Beauveria bassiana ATCC 7159 afforded three new metabolites identified as curvularin-7-O-β-D-glucopyranoside (2), curvularin-4′-O-methyl-7-O- β-D-glucopyranoside (3), and 6-hydroxycurvularin-4′-O-methyl-6-O- β-D-glucopyranoside (4) resulting from hydroxylation, glucosidation, and methylglucosidation of the substrate. Isolation of 6-methyl-2,4-dihydroxyphenyl- 4′-O-methyl-1-O-β-D-glucopyranoside (5) from the fermentation broth of B. bassiana ATCC 7159 without any added substrate suggested that hydroxylase, glucosyl transferase, and methylase are constitutive enzymes of this organism. © 2005 American Chemical Society and American Society of Pharmacognosy.
• Meade-Tollin, L. C., M., E., Cooper, D., Guild, M., Jon, E., Fritz, A., Zhou, G., Whitesell, L., Liang, J., & A., A. (2004). Ponicidin and Oridonin Are Responsible for the Antiangiogenic Activity of Rabdosia rubescens, a Constituent of the Herbal Supplement PC SPES. Journal of Natural Products, 67(1), 2-4.
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  PMID: 14738375;Abstract: Antiangiogenic activity has been identified in an aqueous EtOH extract of Rabdosia rubescens, a component of the dietary supplement PC SPES. Bioassay-guided fractionation using a novel in vitro human endothelial cell-based assay for angiogenesis afforded the diterpenoids ponicidin (1) and oridonin (2), with significant antiangiogenic activity at subcytotoxic concentrations, suggesting that these constituents may strongly contribute to the demonstrated clinical efficacy of PC SPES as a treatment for advanced prostate cancer.
• Tukov, F. F., Anand, S., Sarma, R., A., A., Matthews, J. C., & Rimoldi, J. M. (2004). Inactivation of the cytotoxic activity of repin, a sesquiterpene lactone from Centaurea repens. Chemical Research in Toxicology, 17(9), 1170-1176.
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  PMID: 15377150;Abstract: Prolonged ingestion of Yellow Starthistle (Centaurea solstitialis) and Russian Knapweed (Centaurea repens) by horses has been shown to result in a fatal neurodegenerative disorder called equine nigropallidal encephalomalacia (ENE). Bioassay-guided fractionation of extracts from Centaurea species using the PC12 cell line have led to the identification of one of several putative agents, which may contribute to ENE, namely, the sesquiterpene lactone (SQL) repin (1), previously linked to ENE due to its abundance in C. repens. To characterize the molecular basis of repin-induced neurotoxicity, the present study was designed to identify reactive functional groups that may contribute overall to its toxicity. The reaction of repin (1) with glutathione (GSH) led to the exclusive addition of GSH to the α-methylenebutyrolactone affording a GSH conjugate (3b) that lacked toxicity in the PC12 cell assay, while selective reduction of the α-methylenebutyrolactone double bond of 1 also resulted in an analogue (2) that was devoid of toxicity relative to the parent compound. Unlike repin, analogue 2 failed to decrease cellular dopamine levels in PC12 cells, further substantiating the requirement of the α- methylenebutyrolactone group. Results from this study are suggestive that GSH depletion by the SQL repin may be a primary event in the etiology of ENE, increasing the susceptibility to oxidative damage.
• Furbacher, T. R., & Gunatilaka, A. A. (2001). Catalytic inhibition of topoisomerase IIα by demethylzeylasterone, a 6-oxophenolic triterpenoid from Kokoona zeylanica. Journal of Natural Products, 64(10), 1294-1296.
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  PMID: 11678653;Abstract: In a study to evaluate celastroloids as potential anticancer agents, demethylzeylasterone (5), a 6-oxophenolic triterpenoid from Kokoona zeylanica, was found to be an inhibitor of the enzyme topoisomerase IIa (IC50. = 17.ΜM). Studies of the relationship of this inhibitor to both DNA and the enzyme resulted in 5 being classified as a "catalytic inhibitor" of topoisomerase II. Demethylzeylasterone selectively inhibits the growth of the breast cancer cell line MCF-7 (IC50 = 12.5ΜM) without inhibiting the growth of non-small cell lung cancer (NCI-H460) and CNS glioma (SF-268) cell lines. This is the first report of topoisomerase II inhibitory activity in a celastroloid.
• Gunatilaka, A. L., Berger, J. M., Evans, R., Miller, J. S., Wisse, J. H., Neddermann, K. M., Bursuker, I., & G., D. (2001). Isolation, synthesis, and structure - Activity relationships of bioactive benzoquinones from Miconia lepidota from the suriname rainforest. Journal of Natural Products, 64(1), 2-5.
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  PMID: 11170656;Abstract: Bioactivity-directed fractionation of an EtOAc extract from the leaves of Miconia lepidota afforded the two benzoquinones 2-methoxy-6-heptyl-1,4-benzoquinone (1) and 2-methoxy-6-pentyl-1,4-benzoquinone (primin) (2). This is the first reported isolation of 1. Both quinones 1 and 2 exhibited activity toward mutant yeast strains based on Saccharomyces cerevisiae, indicative of their cytotoxicity and potential anticancer activity. A number of previously synthesized and new analogues were prepared and tested in the same strains. Compounds 1, 2, 2-methoxy-6-butyl-1,4-benzoquinone (5), and 2-methoxy-6-decyl-1,4-benzoquinone (6) were tested in two cytotoxicity assays. In the M109 tumor cell lines, quinones 1, 2, and 6 had an IC50 value of 10 μg/mL. In the A2780 cell line, compounds 1, 2 and 5 had IC50 values of 7.9, 2.9, and 3.2/ μg/mL, respectively.
• Nissanka, A. P., Karunaratne, V., Bandara, B., Kumar, V., Nakanishi, T., Nishi, M., Inada, A., Tillekeratne, L., Wijesundara, D., & Gunatilaka, A. (2001). Antimicrobial alkaloids from Zanthoxylum tetraspermum and caudatum. Phytochemistry, 56(8), 857-861.
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  PMID: 11324918;Abstract: Two benzophenanthrene alkaloids, 8-acetonyldihydronitidine and 8-acetonyldihydroavicine were isolated from Zanthoxylum tetraspermum stem bark along with liriodenine, sesamin, lichexanthone and (+)-piperitol-γ,γ-dimethylallylether. The-species endemic to Sri Lanka, Z. caudatum, contained sesamin, savinin, liriodenine, decarine and 8-O-desmethyl-N-nornitidine. 8-Acetonyldihydronitidine and 8-acetonyldihydroavicine showed significant antibacterial activity while the former along with liriodenine was strongly antifungal. Savinin exhibited potent spermicidal activity. Both savinin and sesamin exhibited significant insecticidal activity. © 2001 Published by Elsevier Science Ltd.
• Wijeratne, E. M., Lankananda, B. D., Tezuka, Y., Nagaoka, T., & Gunatilaka, A. A. (2001). Dimeric aporphine alkaloids of Phoenicanthus obliqua from Sri Lanka. Journal of Natural Products, 64(11), 1465-1467.
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  PMID: 11720536;Abstract: A new dimeric aporphine alkaloid, phoenicanthusine (1), and six known alkaloids were isolated from the stem bark of Phoenicanthus obliqua. The structure of 1 was elucidated by 1D (1H, 13C) and 2D (1H-1H COSY, HMQC, HMBC, and NOESY) NMR and HRMS studies. Phoenicanthusine represents the first example of a N-6-C-4′ and C-7-C-5′ linked dimeric aporphine alkaloid.
• A., A., Paul, V. J., Park, P. U., Puglisi, M. P., Gitler, A. D., Eggleston, D. S., Haltiwanger, R. C., & G., D. (1999). Apakaochtodenes A and B: Two tetrahalogenated monoterpenes from the red marine alga Portieria hornemannii. Journal of Natural Products, 62(10), 1376-1378.
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  PMID: 10543896;Abstract: The structure of apakaochtodene A, the minor isomer of two tetrahalogenated ochtodene monoterpenes, isolated from the red marine alga Portieria hornemannii (Lyngbye) Silva has been identified as 6(S(*))bromo- 1,4(S(*)),8(R(*))-trichloro-2(Z)-ochtodene (1) by NMR spectral and X-ray crystallographic analysis. Its geometrical isomer, apakaochtodene B (2), which could not be separated from I and thus characterized as a 95:5 mixture of 2:1 had 1H and 13C NMR spectral characteristics similar to previously known ochtodene (3) and the related tetrahalogenated monoterpene 4.
• A., A., Ramdayal, F. D., Sarragiotto, M. H., G., D., Sackett, D. L., & Hamel, E. (1999). Synthesis and biological evaluation of novel paclitaxel (Taxol) D-ring modified analogues. Journal of Organic Chemistry, 64(8), 2694-2703.
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  Abstract: The semisynthesis and biological activity of paclitaxel (Taxol) analogues in which the oxygen atom in ring D is substituted by a sulfur or a selenium atom is presented. These derivatives were synthesized and tested in order to make more transparent the role of the oxetane ring in the biological activity of paclitaxel. The sulfur derivatives were found to be less active than paclitaxel in biological assays, while the selenium derivative could not be converted to its 4-acyl analogue. The results with the sulfur analogues suggest that the oxygen atom in the oxetane ring plays an important role in the mechanism by which paclitaxel exhibits its anticancer activity.
• G., D., Chaudhary, A. G., Chordia, M. D., Gharpure, M., A., A., Higgs, P. I., Rimoldi, J. M., Samala, L., Jagtap, P. G., Giannakakou, P., Jiang, Y. Q., Lin, C. M., Hamel, E., Long, B. H., Fairchild, C. R., & Johnston, K. A. (1998). Synthesis and biological evaluation of 2-acyl analogues of paclitaxel (Taxol). Journal of Medicinal Chemistry, 41(19), 3715-3726.
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  PMID: 9733497;Abstract: The anticancer drug paclitaxel (Taxol) has been converted to a large number of 2-debenzoyl-2-aroyl derivatives by three different methods. The bioactivities of the resulting analogues were determined in both tubulin polymerization and cytotoxicity assays, and several analogues with enhanced activity as compared with paclitaxel were discovered. Correlation of cytotoxicity in three cell lines with tubulin polymerization activity showed reasonable agreement. Among the cell lines examined, the closest correlation with antitubulin activity was observed with a human ovarian carcinoma cell line.
• Gunatilaka, A. L. (1998). Chapter 1 Alkaloids From Sri Lankan Flora^*. Alkaloids: Chemistry and Biology, 52(C), 1-101.
• Gunatilaka, A. L., Da, V., Dagne, E., Hofmann, G. A., Johnson, R. K., McCabe, F. L., Mattern, M. R., & G., D. (1998). Limonoids showing selective toxicity to DNA repair-deficient yeast and other constituents of Trichilia emetica. Journal of Natural Products, 61(2), 179-184.
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  PMID: 9514005;Abstract: Bioactivity-directed fractionation of the MeCOEt extract of Trichilia emetica (Meliaceae) resulted in the isolation of the limonoids nymania 1 (1), drageana 4 (3), trichilin A (4), rohituka 3 (5), and Tr-B (7) and the novel seco-A protolimonoid 8. Of these, nymania 1 and Tr-B showed selective inhibitory activity toward DNA repair-deficient yeast mutants. The isolation, structure elucidation, 13C NMR spectral assignments, and biological activities of these compounds are reported.
• Liang, J. Y., Huang, K. S., Gunatilaka, A. L., & Yang, L. (1998). Two new taxane diterpenoids from Taxus chinensis. Chinese Chemical Letters, 9(1), 45-49.
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  Abstract: Two new taxane diterpenoids, 2-deacetoxy-7,9-dideacetyltaxinine J (1) and 2-deacetoxytaxinine B (3), were isolated from the barks of Taxus chinensis. Their structures were elucidated by spectroscopic methods.
• Liang, J., Huang, K., & Gunatilaka, A. L. (1998). A new 1,2-deoxytaxane diterpenoid from Taxus chinensis. Planta Medica, 64(2), 187-188.
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  PMID: 17253235;Abstract: The bark of Taxus chinensis yielded a new taxane diterpenoid, 2- deacetoxy-7,9-dideacetyltaxinine J (1) together with several known taxoids. 1H- and 13C-NMR data of 1 are reported.
• Liang, J., Huang, K., A., A., & Yang, L. (1998). 2-deacetoxytaxinine B: A taxane diterpenoid from Taxus chinensis. Phytochemistry, 47(1), 69-72.
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  Abstract: 2-Deacetoxytaxinine B, a taxane diterpenoid, was isolated from the stem bark of Taxus chinensis along with six known taxane diterpenoids and the diterpenolignan, brevitaxin. The structure of 2-deacetoxytaxinine was determined with the aid of spectroscopic techniques, including 2D NMR spectroscopy.
• Chongming, W. u., A., A., McCabe, F. L., Johnson, R. K., Spjut, R. W., & G., D. (1997). Bioactive and other sesquiterpenes from Chiloscyphus rivularis. Journal of Natural Products, 60(12), 1281-1286.
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  PMID: 9463110;Abstract: Bioassay-directed fractionation of the methyl ethyl ketone extract of Chiloscyphus rivularis yielded five new sesquiterpenes, 12- hydroxychiloscyphone (2), chiloscypha-2,7-dione (3), 12-hydroxychiloscypha- 2,7-dione (4), chiloscypha-2,7,9-trione (5), and rivulalactone (6) in addition to the known sesquiterpenes, 4-hydroxyoppositan-7-one (7), chiloscyphone (1), and isointermedeol (8). The structure and stereochemistry of rivulalactone, a novel trinorsesquiterpene, was confirmed by its synthesis starting from 1. Compound 2 showed selective bioactivity in our yeast-based DNA-damaging assay and cytotoxicity to human lung carcinoma cells.
• Da, V., Izumisawa, C. M., Claudia, M., M., L., G., D., & Gunatilaka, A. L. (1997). Iridoids from Tocoyena formosa. Phytochemistry, 46(2), 305-308.
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  Abstract: The leaves of Tocoyena formosa afforded two antifungal iridoids α- and β-gardiol, and the new iridoids, mollugoside methyl ester and formosinoside. Formosinoside was characterized as its hexaacetyl derivative.
• Gunatilaka, A. A., Chordia, M. D., & Kingston, D. G. (1997). Efficient conversion of cephalomannine to paclitaxel and 3'-N-acyl-3'-N-debenzoylpaclitaxel analogs. Journal of Organic Chemistry, 62(11), 3775-3778.
• Gunatilaka, A., & Kingston, D. G. (1997). DNA-damaging natural products with potential anticancer activity. Studies in Natural Products Chemistry, 20(PART F), 457-505.
• M., L., A., A., G., D., Patitucci, M. L., & Pinto, A. C. (1997). A bioactive seco-rosane diterpenoid from Vellozia candida. Journal of Natural Products, 60(5), 478-481.
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  PMID: 9170291;Abstract: Bioassay-directed fractionation of the bioactive alcoholic extracts of Vellozia candida yielded a new 6,7-seco-rosane diterpenoid, candidalactone (1), which showed moderate toxicity toward DNA repair-deficient mutants of Saccharomyces cerevisiae. Another new but inactive rosane diterpenoid, candidenodiol (3), was also obtained.
• Dhanabalasingham, B., Karunaratne, V., Tezuka, Y., Kikuchi, T., & A., A. (1996). Biogenetically important quinonemethides and other triterpenoid constituents of Salacia reticulata. Phytochemistry, 42(5), 1377-1385.
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  Abstract: Phytochemical investigation of the outer root bark of Salacia reticulata var. β-diandra (Celastraceae) has resulted in the isolation of two novel quinonemethide triterpenoids (celastroloids), isoiguesterinol and 30- hydroxypristimerin, along with salacenonal, several known celastroloids and friedo-oleanane triterpenoids. Details of the structural elucidation and 1H and 13C NMR spectral assignments of these compounds are presented and their biogenetic significance is discussed.
• Kim, Y. C., Che, Q., A., A., & G., D. (1996). Bioactive steroidal alkaloids from Solanum umbelliferum. Journal of Natural Products, 59(3), 283-285.
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  PMID: 8882430;Abstract: Bioassay-directed fractionation of the MeOH extract of Solanum umbelliferum afforded solasodine (1), O-acetylsolasodine (2), and solasodine 3-O-β-D-glucopyranoside (3). Alkaloids 1 and 2 exhibited significant activity toward DNA repair-deficient yeast mutants, whereas 3 and the synthetic analogues N-acetylsolasodine (4) and N,O-diacetylsolasodine (5) were found to be inactive. Compounds 2 and 3 are new natural products.
• Kim, Y. C., Da, V., Baj, N., A., A., & G., D. (1996). A DNA-damaging sesquiterpene and other constituents from Frullania nisquallensis. Planta Medica, 62(1), 61-63.
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  PMID: 17252410;Abstract: Bioassay-guided fractionation of an MeCOEt extract of Frullania nisquallensis Sull. has furnished a DNA-damaging sesquiterpene, costunolide (1), and two inactive compounds, a sesquiterpene (-)-frullanolide (2) and a tridepside tenuiorin (3). 13C-NMR data of 3 are reported.
• Phillips, W. R., Baj, N. J., A., A., & G., D. (1996). C-geranyl compounds from Mimulus clevelandii. Journal of Natural Products, 59(5), 495-497.
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  PMID: 8778239;Abstract: Fractionation of the MeCOEt extract of Mimulus clevelandii yielded the novel 4-geranyl-5-hydroxy-2(3H)-benzofuranone (1) and the five known 6- geranylflavanones diplacone (2a), 3'-O-methyldiplacone (2b), diplacol (2c), mimulone (2d), and 3'-O-methyldiplacol (2e). 2D-NMR methods required revision of assignments for diplacone and diplacol and resolved the uncertainty in the site of methylation for the methyl ethers.
• Wijeratne, E. K., Hatanaka, Y., Kikuchi, T., Tezuka, Y., & Gunatilaka, A. L. (1996). A dioxoaporphine and other alkaloids of two annonaceous plants of sri lanka. Phytochemistry, 42(6), 1703-1706.
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  Abstract: A new 4.5-dioxoaporphine alkaloid, 8-methoxyyouregidione, along with artabotrine, ouregidione, liriodenine, oxocrebanine, oxobuxifoline, atherospermidine and lanuginosine have been isolated from Artobotrys zeylanicus. Investigation of Xylopia championii afforded O-methylmoschatoline and dicentrinone.
• Da, V., A., A., & G., D. (1995). Bioactive guanidine alkaloids from Pterogyne nitens. Journal of Natural Products, 58(11), 1683-1688.
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  Abstract: Bioactivity-guided fractionation of a methanolic CHCl3 extract of the leaves of Pterogyne nitens afforded the known guanidine alkaloid pterogynidine [2] and three new guanidine alkaloids, nitensidines A [3], B [4], and C [5], all of which exhibited selective activity towards the DNA repair-deficient yeast mutant RS 321 (IC12=9.3-20.0 μg/ml); 3,4, and 5 were moderately cytotoxic to CHO Aux B1 cells (IC50=8.5-13.0 μg/ml).
• Wijeratne, E. K., B., L., Kikuchi, T., Tezuka, Y., A., A., & G., D. (1995). Cyathocaline, an azafluorenone alkaloid from Cyathocalyx zeylanica. Journal of Natural Products, 58(3), 459-462.
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  Abstract: Bioactivity-guided fractionation of a MeOH extract of the stem bark of Cyathocalyx zeylanica afforded a moderately bioactive new azafluorenone alkaloid, cyathocaline, the structure of which was established as 5,7-dihydroxy-6-methoxy-1-methyl-4-azafluoren-9-orie [1] with the aid of spectroscopic data.
• Wijeratne, E. K., Gunatilaka, A. L., Kingston, D. G., Haltiwanger, R. C., & Eggleston, D. S. (1995). Artabotrine: A novel bioactive alkaloid from Artabotrys zeylanicus. Tetrahedron, 51(29), 7877-7882.
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  Abstract: The structure of artabotrine, an unprecedented bioactive N-methoxylated alkaloid from Artabotrys zeylanicus, has been deduced as N-methoxynorcepharadione A (1) from spectral data and single crystal X-ray analysis. The known oxoaporphine alkaloid, atherospennidine (2), was also isolated and shown to be active in a mechanism-based yeast bioassay. © 1995 Elsevier Science Ltd.
• da, V., Gunatilaka, A. L., & Kingston, D. G. (1995). Bioactive and other piperidine alkaloids from Cassia leptophylla. Tetrahedron, 51(21), 5929-5934.
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  Abstract: Four new piperidine alkaloids, leptophyllin A (4), 3-acetylleptophyllin A (5), leptophyllin B (8), and (-)-spectaline (1), and 3 known piperidine alkaloids, (-)-spectalinine (2), canavaline (3), and iso-6-canavaline (7), were isolated by a bioassay-guided fractionation of a leaf extract of Cassia leptophylla. The alkaloids 1-3 were active in a mechanism-based DNA-modifying yeast assay and 2 was moderately active in Vero monkey and Chinese hamster ovary cell cytotoxicity assays. © 1995.
• A., A., G., D., M., E., M., B., Hofmann, G. A., & Johnson, R. K. (1994). Biological activity of some coumarins from Sri Lankan Rutaceae. Journal of Natural Products, 57(4), 518-520.
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  PMID: 8021652;Abstract: Twelve coumarins isolated from plants of the Rutaceae collected in Sri Lanka have been subjected to a mechanism-based anticancer bioassay employing DNA repair-deficient and repair-proficient yeasts. Of these, seselin [10] and xanthyletin [11] were found to be active. Seselin also exhibited moderate cytotoxicity.
• Chaudhary, A. G., Gharpure, M. M., Rimoldi, J. M., Chordia, M. D., A., A., G., D., Grover, S., Lin, C. M., & Hamel, E. (1994). Unexpectedly facile hydrolysis of the 2-benzoate group of taxol and syntheses of analogs with increased activities. Journal of the American Chemical Society, 116(9), 4097-4098.
• Dagne, E., Gunatilaka, A., Asmellash, S., Abate, D., Kingston, D. G., Hofmann, G. A., & Johnson, R. K. (1994). Two new cytotoxic cytochalasins from Xylaria obovata. Tetrahedron, 50(19), 5615-5620.
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  Abstract: Two new cytotoxic cytochalasins were isolated by brine shrimp bioassay-guided fractionation from a culture of the wood inhabiting fungus, Xylaria obovata. Their structures were determined as 19,20-epoxycytochalasin Q (1) and its deacetyl analog 2 by the application of spectroscopic techniques and chemical correlation with cytochalasin R. Acetylation of 2 yielded 1. Both 1 and 2 were cytotoxic but were found to be inactive in an HIV-protease inhibitory assay and a mechanism-based DNA damaging yeast assay. © 1994.
• Harrigan, G. G., A., A., G., D., Chan, G. W., & Johnson, R. K. (1994). Isolation of bioactive and other oxoaporphine alkaloids from two annonaceous plants, Xylopia aethiopica and Miliusa cf. banacea. Journal of Natural Products, 57(1), 68-73.
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  PMID: 8158166;Abstract: The oxoaporphine alkaloids oxophoebine [1] and liriodenine [2] have been isolated from Xylopia aethiopica (Annonaceae). Both showed selective toxicity against DNA repair and recombination deficient mutants of the yeast Saccharomyces cerevisiae. Three related but inactive compounds, oxoglaucine [3], O-methylmoschatoline [4], and lysicamine [5], were also isolated from this plant. Selective toxicity was also observed for 10-methoxyliriodenine (lauterine) [6] and 10-hydroxyliriodenine [7], two oxoaporphine alkaloids isolated from Miliusa cf. banacea (Annonaceae). The structure of 10-hydroxyliriodenine [7], a novel oxoaporphine, was determined by spectroscopic methods and chemical conversion to compound 6. The role of the bioactive oxoaporphine alkaloids as DNA topoisomerase inhibitors is discussed.
• Harrigan, G. G., S.Bolzani, V. d., Gunatilaka, A. L., & Kingston, D. G. (1994). Kaurane and trachylobane diterpenes from Xylopia aethiopica. Phytochemistry, 36(1), 109-113.
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  Abstract: Phytochemical investigation of Xylopia aethiopica (Annonaceae) has resulted in the isolation of two novel diterpenes, 15-oxo-(-)-trachyloban-19-oic acid and (-)-kaur-15-en-17-al-19-oic acid. Also encountered were the known compounds 15-hydroxy-(-)-trachyloban-19-oic acid, 15β-hydroxy-(-)-kaur-16-en-19-oic acid (as an inseperable mixture), 15-oxo-(-)-kaur-16-en-19-oic acid and sitosterol glucoside. 13C NMR assignments of 15-hydroxy-(-)- trachyloban-19-oic acid and the assignment of the configuration of its hydroxyl group at C-15 have been carried out for the first time. © 1994.
• Heltzel, C. E., A., A., G., D., Hofmann, G. A., & Johnson, R. K. (1994). Synthesis and structure-activity relationships of cytotoxic 7-hydroxy sterols. Journal of Natural Products, 57(5), 620-628.
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  PMID: 8064294;Abstract: The cytotoxic sterols 1 and 2, previously isolated from Pseudobersama mossambicensis, have been synthesized in nine steps from stigmasterol, together with seven related sterols. Structure-activity relationships of these sterols in cytotoxicity and DNA-damaging assays are discussed.
• Kingston, D. G., Chaudhary, A. G., Gunatilaka, A., & Middleton, M. L. (1994). Synthesis of taxol from baccatin III via an oxazoline intermediate. Tetrahedron Letters, 35(26), 4483-4484.
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  Abstract: Taxol (1) can be prepared in good yield by coupling the oxazoline carboxylic acid 5 with 7-(triethylsilyl)baccatin III, followed by hydrolysis. The oxazolines 7 and 8 can also be prepared directly from taxol. © 1994.
• Tezuka, Y., Kikuchi, T., Dhanabalasingham, B., Karunaratne, V., & A., A. (1994). Studies on terpenoids and steroids, 25. Complete ¹H-and ¹³C-NMR spectral assignments of salaciquinone, a new 7-oxo-quinonemethide dinortriterpenoid. Journal of Natural Products, 57(2), 270-276.
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  Abstract: A new 7-oxo-quinonemethide dinortriterpenoid, salaciquinone [1], and a known quinonemethide dinortriterpenoid, isoiguesterin [3], were isolated from the root bark of Salacia reticulata var. β-diandra (Celastraceae). The structure elucidation of salaciquinone was based on detailed 2D and nOe-difference nmr spectroscopy, leading to the complete assignment of the 1H-and 13C-nmr spectra and revision of some 1H-nmr spectral assignments made previously for the related 7-oxo-quinonemethide nortriterpenoid, dispermoquinone [2]. Complete 1H- and 13C-nmr spectral assignments of isoiguesterin were also made, also leading to revision of some 13C-nmr assignments previously made for this compound.
• Valente, L. M., Gunatilaka, A. L., Kingston, D. G., & Pinto, A. C. (1994). Norcucurbitacin gentiobiosides from Fevillea trilobata. Journal of Natural Products, 57(11), 1560-1563.
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  PMID: 7853005;Abstract: The new norcucurbitacin glycosides, andirobicin A gentiobioside [2], and andirobicin C gentiobioside [1], and the known fevicordin F gentiobioside [3], were isolated from the aqueous MeOH fraction of a liquid-liquid partition of the MeOH extract of the seeds of Fevillea trilobata. Their structures were determined by nmr and ms techniques.
• Dagne, E., A., A., G., D., Alemu, M., Hofmann, G., & Johnson, R. K. (1993). Two bioactive pterocarpans from Erythrina burana. Journal of Natural Products, 56(10), 1831-1834.
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  PMID: 8277323;Abstract: Bioactivity-directed fractionation of the CHCl3 extract of the bark of Erythrina burana afforded phaseollidin [1] and cristacarpin [2]. Both 1 and 2 exhibited moderate but selective activity towards DNA repair-deficient yeast mutants, whereas only 1 was found to be cytotoxic. 13C-nmr spectra of both compounds were assigned.
• Dagne, E., Gunatilaka, A. L., G., D., & Alemu, M. (1993). 4′-O-methylstephavanine from Stephania abyssinica. Journal of Natural Products, 56(11), 2022-2025.
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  PMID: 8289070;Abstract: An EtOH extract of the roots of Stephania abyssinica (Menispermaceae) contained stephavanine [2] and a new alkaloid, 4′-O-methylstephavanine [1].
• Gunatilaka, A., Dhanabalasingham, B., Karunaratne, V., Kikuchi, T., & Tezuka, Y. (1993). Studies on terpenoids and stereoids. Part 27. Structure of a D:A-friedo-oleanane triterpenoid from salacia reticulata and revision of the structures of kokoonol and kokzeylanol series of triterpenoids. Tetrahedron, 49(45), 10397-10404.
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  Abstract: The structure of epi-kokoondiol isolated from the outer root bark of Salacia reticulata var. β-diandra has been elucidated as 21α,26-dihydroxy-D:A-friedo-oleanan-3-one (1) by the application of 2D and NOE difference NMR spectroscopy. Reinvestigation of some KoKoona triterpenoids by NOE difference spectroscopy led to the revision of the structures of kokoondiol, kokoononol, kokzeylanol, kokoonol, and kokzeylanonol as 21β,26-dihydroxy-D:A-friedo-oleanan-3-one (2), 26-hydroxy-D:A-friedo-oleanane-3,21-dione (3), 6β,26-dihydroxy-D:A-friedo-oleanan-3-one (4) 26-hydroxy-D:A-friedo-oleanan-3-one (5), and 6β,26-dihydroxy-D:A-friedo-oleanane-3,21-dione (6), respectively. © 1993.
• Harrigan, G. G., Ahmad, A., Baj, N., Glass, T. E., Gunatilaka, A. A., & Kingston, D. G. (1993). Bioactive and other sesquiterpenoids from Porella cordeana. Journal of Natural Products, 56(6), 921-925.
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  PMID: 8350093;Abstract: Bioassay-directed fractionation of the MeCOEt extract of Porella cordeana yielded drimenin [1] and aristolone [4], which were moderately toxic towards DNA-repair-deficient mutants of Saccharomyces cerevisiae. Three inactive sesquiterpenes, 7-ketoisodrimenin [2], 7-ketoisodrimenin-5-ene [3], and norpinguisanolide, were also obtained. Compounds 2 and 3 are new.
• Heltzel, C. E., A., A., Glass, T. E., G., D., Hoffmann, G., & Johnson, R. K. (1993). Bioactive furanonaphthoquinones from Crescentia cujete. Journal of Natural Products, 56(9), 1500-1505.
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  PMID: 8254347;Abstract: Bioassay-directed fractionation of the MeCOEt extract of Crescentia cujete (Bignonaceae) resulted in the isolation of (2S,3S)-3-hydroxy-5,6-dimethoxydehydroiso-α-lapachone [1], (2R)-5,6-dimethoxydehydroiso-α-lapachone [2], (2R)-5-methoxydehydroiso-α-lapachone [3], 2-(1-hydroxyethyl)naphtho[2,3-b]furan-4,9-dione [4], 5-hydroxy-2-(1-hydroxyethyl)naphtho[2,3-b]furan-4,9-dione[5],2- isopropenylnaphtho[2,3-b]furan-4,9-dione [6], and 5-hydroxydehydroiso-α-lapachone [7]. Compounds 1-3 are new, and all compounds are bioactive, showing selective activity towards DNA-repair-deficient yeast mutants. The isolation, structure elucidation, and biological activities of these compounds are reported.
• Heltzel, C. E., Gunatilaka, A. L., Glass, T. E., & Kingston, D. G. (1993). Furofuranonaphthoquinones: bioactive compounds with a novel fused ring system from crescentia cujete. Tetrahedron, 49(31), 6757-6762.
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  Abstract: Bioassay-directed fractionation of the methyl ethyl ketone extract of Crescentia cujete yielded the naphthoquinones 1 and 2. Both compounds are cytotoxic, and 1 shows selective DNA-damaging activity against yeast. Detailed spectroscopic interpretation led to the assignment of the structures of 1 and 2 as 3-hydroxymethylfuro[3,2-b]naphtho[2,3-d]furan-5,10-dione and 9-hydroxy-3-hydroxymethylfuro[3,2-b]naphtho[2,3-d]furan-5,10-dione, respectively. This is the first report of this fused furofuran ring system, either as a natural product or a synthetic substance. © 1993.
• M., L., A., A., Glass, T. E., G., D., & Pinto, A. C. (1993). New norcucurbitacin and heptanorcucurbitacin glucosides from Fevillea trilobata. Journal of Natural Products, 56(10), 1772-1778.
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  PMID: 8277315;Abstract: From the MeOH extract of the seeds of Fevillea trilobata (Cucurbitaceae) were isolated fevicordin A glucoside [1], cayaponoside B [2], cayaponoside D [3], a new norcucurbitacin glucoside, and a new heptanorcucurbitacin glucoside. The structure of the new norcucurbitacin glucoside, andirobicin A glucoside, was established as 29-nor-1,2,3,4,5,10-dehydro-25-methoxy-2-O-β-D-glucopyranosyl-3,16α, 20R,22ξ-tetrahydroxy-11-oxocucurbit-23-ene [4], and that of the novel heptanorcucurbitacin glucoside, andirobicin B glucoside, as 22,23,24,25,26,27,29-heptanor-1,2,3,4,5,10-dehydro-2-O-β-D-glucopyranosyl- 3,16α-dihydroxycucurbita-11,20-dione [5].
• Tezuka, Y., Kikuchi, T., Dhanabalasingham, B., Karunaratne, V., & Gunatilaka, A. A. (1993). Salacenonal: A novel nortriterpenoid aldehyde of biogenetic significance from Salacia reticulata. Natural Product Letters, 3(4), 273-276.
• Tezuka, Y., Kikuchi, T., Fernando, H., & Gunatilaka, A. (1993). ¹H and ¹³C NMR spectral assignments of some ene-quinonemethide nortriterpenoids. Phytochemistry, 32(6), 1531-1534.
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  Abstract: The 1H and 13C NMR spectra of three natural 14(15)-ene-quinonemethide nortriterpenoids, balaenonol, balaenol and isobalaendiol have been comple. © 1993.
• A., A., Samaranayake, G., G., D., Hoffmann, G., & Johnson, R. K. (1992). Bioactive ergost-5-ene-3β, 7α-diol derivatives from Pseudobersama mossambicensis. Journal of Natural Products, 55(11), 1648-1654.
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  PMID: 1479381;Abstract: Bioactivity-directed fractionation of the methyl ethyl ketone extract of Pseudobersama mossambicensis resulted in the isolation of ergosta-5,24(28)-diene-3β,7α-diol [1], 24,28-epoxyergost-5-ene-3β,7α-diol [2], and ergost-5-ene-3β,7α,24,28-tetraol [3]. All three sterols showed selective activity towards DNA repair-deficient yeast mutants. The sterol 1 also showed cytotoxicity towards wild-type P-388 murine leukemia cells. The isolation, structural elucidation, and biological activities of these sterols are reported. The sterol 3 is most probably an artifact formed from 2 during the isolation process.
• G., D., Gunatilaka, A. L., & Ivey, C. A. (1992). Modified taxols, 7 . A method for the separation of taxol and cephalomannine. Journal of Natural Products, 55(2), 259-261.
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  PMID: 1352536;Abstract: Taxol [1] can be separated from the closely related co-occurring diterpenoid cephalomannine [2] by oxidation of a mixture of the two with OsO4 and flash chromatography of the resulting products.
• M., E., M., B., A., A., Tezuka, Y., & Kikuchi, T. (1992). Chemical constituents of three rutaceae species from Sri Lanka. Journal of Natural Products, 55(9), 1261-1269.
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  Abstract: The stem bark of Luvunga angustifolia yielded a new acridone alkaloid, 5-methoxyarborinine [1], and several known compounds. Several known compounds were also isolated from Limonia acidissima. Pleiospermium alatum afforded a rare coumarin glycoside, apiosylskimmin [5], and two known limonoids 6 and 7. Nmr studies of 6 demonstrated strong nOe effects due to "through-space" coupling and led to revision of some previous carbon signal assignments. A probable biosynthetic relationship between some limonoids of the Rutaceae is suggested.
• Bandara, B., Gunatilaka, A., Wijeratne, E., & MacLeod, J. K. (1990). Acridone alkaloids and coumarins from Pleiospermium alatum. Phytochemistry, 29(1), 297-301.
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  Abstract: The root bark of Pleiospermium alatum afforded five alkaloids, five coumarins, lupeol and stigmasterol. One of the acridones, 1,5,6-trihydroxy-2,3-dimethoxy-10-methyl-9-acridone is a new compound while another, 1-hydroxy-2,3,5,6-tetramethoxy-10-methyl-9-acridone, is a new natural product. Chemotaxonomic aspects of the occurrence of acridone and coumarins in Pleiospermium is discussed. Seselin, one of the coumarins encountered displayed significant antifungal activity against Cladosporium cladosporioides. © 1990.
• Dehmlow, E. V., Sleegers, A., Risch, N., Trowitzsch-Kienast, W., Wray, V., & Gunatilaka, A. (1990). Structure revision of a minor alkaloid from Broussonetia zeylanica. Phytochemistry, 29(12), 3993-3995.
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  Abstract: It is shown by spectroscopic methods and synthesis that the minor alkaloid C10H8N2O2 from Broussonetia zeylanica is actually 8-hydroxyquinoline-4-carbaldehyde oxime and not 3,4′-dihydroxy-2,3′-bipyridine as was reported earlier. © 1990.
• Gamlath, C. B., Gunatilaka, A. L., Tezuka, Y., Kikuchi, T., & Balasubramaniam, S. (1990). Quinone-methide, phenolic and related triterpenoids of plants of Celastraceae: further evidence for the structure ofCelastranhydride. Phytochemistry, 29(10), 3189-3192.
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  Abstract: Quinone-methide and phenolic triterpenoids of the root outer bark ofCelastrus paniculatus have been identified as celastrol, pristimerin, zeylasterone and zeylasteral whereas those ofKokoona reflexa root outer bark were pristimerin, zeylasterone and zeylasteral. Celastranhydride, an unusual triterpene anhydride isolated fromK. zeylanica was shown to be present inK. reflexa, Cassine balae andReissantia indica. Details of the isolation and structure elucidation of celastranhydride are presented along with the analysis of1H-detected heteronuclear multiple-bond multi-quantum correlation (HMBC) NMR spectrum which aided the confirmation of its structure. Extracts ofC. balae, Gymnosporia emarginata, Pleurostylia opposita andR. indica were found to contain quinone-methides but were devoid of phenolic triterpenoids. The biosynthetic and chemotaxonomic significance of the co-occurrence of these triterpenoids in Celastraceae is discussed. © 1990 Pergamon Press plc.
• Fernando, H. C., Gunatilaka, A. L., Tezuka, Y., & Kikuchi, T. (1989). Studies on terpenoids and steroids - 18 balaenonol, balaenol and isobalaendiol: Three new 14(15)-ene-quinone-methide triterpenoids from cassine balae. Tetrahedron, 45(18), 5867-5876.
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  Abstract: The three new 14(15)-ene-quinone-methide triterpenoids, balaenonol, balaenol and isobalaendiol, isolated from Cassine balae have been shown to be 3,21β-dihydroxy-2,22-dioxo-3,5,7,10(1),14(15)-pentaen-(14→15)-D:A-friedo-24,29-dinoroleanane (1), 3,21β-dihydroxy-2-oxo-3,5,7,10(1),14(15)-pentaen-(14→15)-D:A-friedo-24,29-dinoroleanane (2) and 3,21β,22β-trihydroxy-2-oxo-3,5,7,10(1),14(15)-pentaen-(14→15)-D:A-friedo-24,30-dinoroleanane (3), respectively, on the basis of spectroscopic evidence. The possible biosynthetic origin of these 14(15)-ene-quinone-methides from pristimerin is discussed. © 1989.
• Gamlath, C. B., A., A., & Subramaniam, S. (1989). Studies on terpenoids and steroids. Part 19. Structures of three novel 19(10→9)abeo-8α,9β,10α-euphane triterpenoids from reissantia indica (celastraceae). Journal of the Chemical Society, Perkin Transactions 1, 2259-2267.
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  Abstract: The three novel 19(10→9)abeo-8α,9β,10α-euphane (reissantane) triterpenoids isolated from Reissantia indica (Celastraceae) and related to reissantioloxide (reissantenol oxide) (1) have been shown to be 24-oxoreissant-5-ene-3β,25-diol (2), 3-oxoreissant-5-ene-24β,25-diol (3), and reissant-5-ene-3β,24β,25-triol (4). A possible biosynthetic relationship for reissantane, D:B-friedo-oleanane, D:A-friedo-oleanane, and quinone-methide triterpenoids which occur in R. indica is presented.
• Gunatilaka, A., Fernando, H., Qureshi, M., & Balasubramaniam, S. (1989). Neisosposinine: A new oxindole alkaloid from neisosperma oppositifolia [Apocynaceae]. Heterocycles, 28(2), 999-1005.
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  Abstract: A new oxindole alkaloid named neisosposinine was isolated from the stem bark of Neisosperma oppositifolia and its structure was elucidated as (1) with the aid of spectroscopic data. The C-18 methyl epimer of (1), isocarapanaubine (2) was also isolated along with three indole alkaloids, reserpiline (3), isoreserpiline (4) and ochroposinine (5). © 1989.
• Macleod, J. K., D., P., M., B., A., A., & M., E. (1989). Acidissimin, a new limonoid from Limonia acidissima. Journal of Natural Products, 52(4), 882-885.
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  Abstract: Two limonoids, obacunone [1] and acidissimin [2] have been isolated from the stem bark and root bark, respectively, of Limonia acidissima. Acidissimin is a new compound whose structure has been elucidated by spectroscopic means.
• Bandara, B. M., Gunatilaka, A. A., & Wijeratne, E. M. (1988). Coumarins from Pleiospermium alatum.. Planta Medica, 54(1), 91-92.
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  PMID: 3375343;
• Bandara, B. R., Gunatilaka, A. L., Wijeratne, E. K., & Adikaram, N. K. (1988). Antifungal constituents of Limonia acidissima. Planta Medica, 54(4), 374-375.
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  PMID: 3222382;
• Bokel, M., Diyasena, M., Gunatilaka, A., Kraus, W., & Sotheeswaran, S. (1988). Canaliculatol, an antifungal resveratrol trimer from Stemonoporous canaliculatus. Phytochemistry, 27(2), 377-380.
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  Abstract: A new resveratrol trimer, canaliculatol, has been isolated from the bark of Stemonoporus canaliculatus. Canaliculatol showed antifungal activity against the fungus, Cladosporium cladosporioides. The structure and stereochemistry of canaliculatol is reported in this paper. © 1988.
• Fernando, H., Gunatilaka, A., Kumar, V., Weeratunga, G., Tezuka, Y., & Kikuchi, T. (1988). Two new quinone-methides from cassine balae: Revised structure of balaenonol. Tetrahedron Letters, 29(3), 387-390.
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  Abstract: The structure of balaenol, a new quinone-methide triterpene isolated from Cassine balae has been deduced as 1 and the structure of the previously isolated balaenonol has been revised as 2 from their spectral data including 2-D heteronuclear 1H13C shift correlated NMR spectra and n.O.e studies. © 1988.
• Gamlath, C. B., & Gunatilaka, A. (1988). Two phenolic friedo-23,24-dinoroleanane triterpenes from Kokoona zeylanica. Phytochemistry, 27(10), 3221-3224.
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  Abstract: Two novel phenolic dinor-triterpenes isolated from Kokoona zeylanica have been identified as 23-nor-6-oxopristimerol and 23-nor-6-oxodemethylpristimerol on the basis of spectroscopic evidence and chemical interconversions. The biosynthetic significance of the co-occurrence of phenolic D:A-friedo-23, 24-dinoroleananes with phenolic and quinone-methide triterpenes in K. zeylanica is discussed. © 1988.
• Gamlath, C. B., A., A., & Schlemper, E. O. (1988). Reissantioloxide: A novel epoxytriterpenoid from Reissantia indica; X-ray crystal structure. Journal of the Chemical Society, Chemical Communications, 249-250.
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  Abstract: The structure and stereochemistry of reissantioloxide, a triterpene epoxide with a novel (24S)-24,25-epoxy-19(10 → 9) abeo-8α,9β,10α- euph-5-en-3β-ol skeleton isolated from Reissantia indica, have been established from spectral data and single-crystal X-ray analysis.
• Gamlath, C. B., Gunatilaka, A. L., Tezuka, Y., & Kikuchi, T. (1988). The structure of celastranhydride: A novel triterpene anhydride of celastraceae. Tetrahedron Letters, 29(1), 109-112.
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  Abstract: The structure of celastranhydride, a novel triterpene anhydride isolated from Kokoona zeylanica and present in Cassine balae and Reissantia indica, all of the family Celastraceae, has been deduced as 1 from its spectral data including 2-D heteronuclear 1H13C shift correlated NMR spectra. © 1988.
• Gamlath, C. B., Gunatilaka, A., Alvi, K. A., & Balasubramaniam, S. (1988). Cucurbitacins of Colocynthis vulgaris. Phytochemistry, 27(10), 3225-3229.
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  Abstract: The methanolic extract of the fruits of Colocynthis vulgaris on acidic hydrolysis afforded in addition to cucurbitacin I and J a new cucurbitacin designated cucurbitacin T whose structure was elucidated as (24S)-16,24-anhydro-25-methoxy-2,16α,20β,24-tetrahydroxy-3,11,22-trioxocucurbita-1,5-diene by spectroscopic methods. The biosynthetic significance of the co-occurrence of cucurbitacins I, J and T in C. vulgaris is discussed. © 1988.
• Gunaherath, G. B., Gunatilaka, A., Cox, P. J., Howie, R., & Thomson, R. H. (1988). A revised structure for plumbazeylanone. Tetrahedron Letters, 29(6), 719-720.
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  Abstract: The structure of plumbazeylanone has been revised, by X-ray crystallography, to 1,2,3,4-tetrahydro-5-hydroxy-1,4-diketo-2-methyl-2,3-di(5′-hydroxy-2'-methyl-1,4-naphthoquinon-3′-yl)naphthalene. © 1988.
• M., G., A., A., & Thomson, R. H. (1988). Studies on medicinal and related plants of Sri Lanka. Part 18. Structure of a new naphthoquinone from Plumbago zeylanica. Journal of the Chemical Society, Perkin Transactions 1, 407-410.
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  Abstract: The isolation of chitranone (3), zeylanone (4), maritinone (5), 2-methylnaphthazarin (6), plumbazeylanone, and a new naphthoquinone, methylene-3,3′-diplumbagin (7) from the phenolic fraction of the light petroleum extract of the roots of Plumbago zeylanica (Plumbaginaceae) is reported. The dimethyl ether of the new quinone has been synthesized from plumbagin methyl ether.
• Gamlath, C. B., Gunaherath, K. B., & Gunatilaka, A. L. (1987). Studies on terpenoids and steroids. Part 10. Structures of four new natural phenolic D:A-friedo-24-noroleanane triterpenoids. Journal of the Chemical Society, Perkin Transactions 1, 2849-2854.
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  Abstract: The three new phenolic nortriterpenes, demethylzeylasteral, zeylasteral, and demethylzeylasterone, isolated from Kokoona zeylanica (Celastraceae), have been shown to be 2,3-dihydroxy-6,23-dioxo-D:A-friedo-24-noroleana-1,3,5(10),7- tetraen-29-oic acid (5), its methyl ester (6), and 2,3-dihydroxy-6-oxo-D:A- friedo-24-noroleana-1,3,5(10),7-tetraene-23,29-dioic acid (7), respectively. The structure of the new phenolic (9→8)-D:A-friedo-24-noroleanane triterpene obtained from 'kokum soap' has been established as 23-oxoisopristimerin III (11) on the basis of spectroscopic evidence. The biosynthetic significance of 23-oxoisopristimerin III is discussed.
• Govindan, S. V., G., D., Gunatilaka, A. A., L., R., Wilkins, T. D., Wit, P. D., Van, M., & Van, A. (1987). Synthesis and biological activity of analogs of fecapentaene-12. Journal of Natural Products, 50(1), 75-83.
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  PMID: 3598600;Abstract: Analogs of the potent fecal mutagen fecapentaene-12 [1] have been prepared and tested both for mutagenicity and for their ability to serve as biological precursors of 1. It was found that mutagenicity in three different Salmonella tester strains TA96, TA100, and TA104, decreased rapidly as the number of conjugated double bonds was reduced. The aldehyde 8, analogous to the hydrolysis product of 1, showed only low mutagenicity, even in the aldehyde-sensitive strain TA104. None of the polyenes prepared was able to function as a direct biological precursor of of 1 under the conditions employed.
• Gunatilaka, A. A., Dhanabalasingham, B., Paredes, L., Jakupovic, J., Bohlmann, F., & Adikaram, N. K. (1987). Microglossic acid an alicyclic diterpene and other consituents of Microglossa zeylanica. Phytochemistry, 26(8), 2408-2409.
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  Abstract: The aerial parts of Microglossa zeylanica collected in Sri Lanka contained β-farnesene, squalene, dammadienyl acetate, caryophyllen-1,10-epoxide, 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone, dehydrofalcarindiol and two new alicyclic diterpenes, microglossic acid and dihydromicroglossic acid. Their structures were elucidated by high field 1H NMR spectroscopy. © 1987.
• Shafiee, A., Vosooghi, M., Francisco, C. G., Freire, R., Hernandez, R., Salazar, J. A., Suarez, E., Sotheeswaran, S., & Gunatilaka, A. (1987). Potential long-acting contraceptive agents: Esters of testosterone with alkoxy- and halogeno-substituted carboxylic acids. Steroids, 49(4-5), 397-402.
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  PMID: 3455051;Abstract: The chemical synthesis and physical data of several new esters of testosterone (17β -hydroxyandrost-4-en-3-one), which contain either a halogeno or an alkoxy substituent in the acid chain, are reported. © 1987.
• Sotheeswaran, S., Diyasena, M. C., Gunatilaka, A. L., Bokel, M., & Kraus, W. (1987). Further evidence for the structure of vaticaffinol and a revision of its stereochemistry. Phytochemistry, 26(5), 1505-1507.
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  Abstract: The resveratrol tetramer, vaticaffinol, has been isolated from the bark of Stemonoporus canaliculatus. Further evidence has been obtained to support its structure. Its stereochemistry has been revised on the results of NOE and 1HNMR homodecoupling experiments. © 1987.
• G., A., Broughton, H. B., Attwood, S. V., & A., A. (1986). Two total syntheses of showdomycin and related studies. Journal of Organic Chemistry, 51(4), 495-503.
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  Abstract: After a series of model reactions, D-ribose (2) was reacted with 3-(triphenylphosphoranylidene)-2,5-pyrrolidinedione (8a) in THF at reflux to produce 3(E)-(2(S),3(S),4(R),5-tetrahydroxy-1-pentylidene)-2,5-pyrrolidinedione (35) (75%). Subsequent cyclization of 35 using phenylselenenyl chloride followed by hydrogen peroxide gave showdomycin (1) (13%) and epi-showdomycin (36) (41%). Using a similar strategy 2,3-O-isopropylidene-D-ribose (37b) was reacted sequentially with 1-(triphenylmethyl)-3-(triphenylphosphoranylidene)-2,5-pyrrolidinedione (8b), phenylselenenyl chloride, hydrogen peroxide, and trifluoroacetic acid to give 1 (3% overall). © 1986 American Chemical Society.
• Arseculeratne, S. N., Gunatilaka, A., & Panabokke, R. G. (1985). Studies on medicinal plants of sri lanka. part 14: toxicity of some traditional medicinal herbs. Journal of Ethnopharmacology, 13(3), 323-335.
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  PMID: 4058035;Abstract: Seventy five medicinal plants of the traditional Ayurvedic pharmacopoeia of Sri Lanka have been screened chemically for alkaloids and pyrrolizidine alkaloids. Of these, Crotolaria juncea L. was found to contain pyrrolizidine alkaloids with biological effects consistent with pyrrolizidine alkaloid toxicity. Feeding trials in rats with three plants lacking pyrrolizidine alkaloids, namely Aegle marmelos (L.) Corr., Hemidesmus indicus (L.) Ait. F. and Terminalia chebula Retz. produced hepatic lesions which included central vein abnormalities while Terminalia chebula and Withania somnifera (L.) Dunal produced marked renal lesions. © 1985.
• Herz, J. E., Torres, J. V., Murillo, A., Cruz, S., Shafiee, A., Vosooghi, M., Sotheeswaran, S., & Gunatilaka, A. A. (1985). Potential long-acting contraceptive agents: Esters and ethersof testosterone with α-and/or β-chain branching. Steroids, 46(6), 947-953.
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  PMID: 3842023;Abstract: The synthesis of ten esters and two ethers of testosterone (17 β-hydroxyandrost-4-en-3-one) is described. All these possess some form of α-and/or β-substitution in the ester/ether sidechain. The work was undertaken in order to evaluate the long-acting antifertility effect of such compounds in males. © 1985.
• Gunatilaka, A. L., & Nanayakkara, N. D. (1984). Studies on terpenoids and steroids-2. Structures of two new tri- and tetra-oxygenated D:A-friedo-oleanan triterpenes from kokoona zeylanica. Tetrahedron, 40(4), 805-809.
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  Abstract: The two D:A-friedo-oleanane triterpenes kokzeylanol and kokzeylanonol isolated from the inner bark of Kokoona zeylanica have been characterized as 6β,27-dihydroxy-D:A -friedo-olean-3-one and 6β,27-dihydroxy-D:A-friedo-olean-3,21-dione, respectively, by the deoxygenation of their 27-acetoxy derivatives using lithium-ethylenediamine reduction coupled with spectroscopic and irradiation methods. Kokzeylanonol represents the first tetra-oxygenated D:A-friedo-oleanane triterpene obtained from a nautral source. Significance of some of these D:A-friedo-oleananes in the biosynthesis of quinonoid triterpenes in Celastraceae is discussed. © 1984.
• Gunatilaka, A., Silva, A. D., Sotheeswaran, S., Balasubramaniam, S., & Wazeer, M. I. (1984). Terpenoid and biflavonoid constituents of Calophyllum calaba and Garcinia spicata from Sri Lanka. Phytochemistry, 23(2), 323-328.
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  Abstract: A new bark acid, isochapelieric acid (cis-chapelieric acid), chapelieric acid, friedelin, friedelan-3β-ol, canophyllal, canophyllol, friedelan-3β,28-diol, canophyllic acid and amentoflavone have been isolated and characterized from leaf extractives of Calophyllum calaba. 13CNMR spectra of methyl chapelierate and methyl isochapelierate have been recorded and interpreted. Leaf extractives of Garcinia spicata afforded an unidentified long chain carboxylic acid, friedelin, friedelan-3β-ol, sitosterol and the biflavanones GB-1, GB-1a, GB-2a and morelloflavone. Chemotaxonomic significance of the occurrence of some of the above foliar constituents in Calophyllum and Garcinia species is discussed. © 1984.
• Gunatilaka, A., Sriyani, H., & Sotheeswaran, S. (1984). Quaesitol, a phenol from Garcinia quaesita. Phytochemistry, 23(11), 2679-2681.
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  Abstract: The petrol extractives of the bark of Garcinia quaesita gave hermonionic acid, its decarboxylated product and a new phenol, quaesitol. © 1984.
• Gunatilaka, A., Surendrakumar, S., & Thomson, R. H. (1984). Broussonetine, a bisquinolyl-γ-butyrolactone from Broussonetia zeylanica. Phytochemistry, 23(4), 929-931.
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  Abstract: The wood of B. zeylanica (Moraceae) contains a new alkaloid broussonetine, identified as 3,4-bis(8- hydroxyquinolin-4-yl)-γ-butyrolactone. © 1984.
• Kamal, G. M., Gunaherath, B., Gunatilaka, A., & Thomson, R. H. (1984). Structure of plumbazeylanone: a novel trimer of plumbagin from plumbago zeylanica. Tetrahedron Letters, 25(42), 4801-4804.
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  Abstract: Plumbazeylanone, a quinone from Plumbago zeylanica is probably 5b,11a,12,12a-tetrahydro-1,7-dihydroxy-5b-(8-hydroxy-3-methyl-1,4-naphthoquinon-2-yl)-5a,12a-dimethyl-5aH-dibenzo[b,h]fluorene-5,13:6,11-diquinone, a novel trimer of plumbagin with an additional methyl group. © 1984.
• A., A., P., N., & Uvais, M. (1983). Studies on terpenoids and steroids. Part 1. Structures of six novel 27-hydroxy and 6β-hydroxy di- and tri-oxygenated D : A-friedo-oleanane triterpenes from Kokoona zeylanica. Journal of the Chemical Society, Perkin Transactions 1, 2459-2469.
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  Abstract: The benzene extract of the inner stem bark of Kokoona zeylanica Thwaites (Celastraceae) contains twelve D : A-friedo-oleananes of which nine are new. The new triterpenes have been classified under three series; kokoonol (3,27-dioxy and 3,21,27-trioxy), zeylanol (3,6-dioxy and 3,6,21 -trioxy), and kokzeylanol (3,6,27-trioxy and 3,6,21,27-tetraoxy). Six of these triterpenes belonging to the kokoonol and zeylanol series have been identified as 27-hydroxy-D : A-friedo-oleanan-3-one (4) (kokoonol), 27-hydroxy-D : A-friedo-oleanane-3,21 -dione (5) (kokoononol), 21 α,27-dihydroxy-D : A-friedo-oleanan-3-one (6) (kokoondiol), 6β-hydroxy-D : A-friedo-oleanan-3-one (21) (zeylanol), 6β-hydroxy-D : A-friedo-oleanane-3,21-dione (22) (zeylanonol) and 6β,21 β-dihydroxy-D : A-friedo-oleanan-3-one (23) (zeylandiol), by spectroscopic methods and chemical interconversions. The biosynthetic significance of 6-hydroxy-D : A-friedo-oleananes is discussed.
• Gunaherath, G. B., & Gunatilaka, A. (1983). Structures of two new phenolic 24-nor-D:A-friedo-oleananes related to zeylasterone: A partial synthesis of trimethylzeylasterone. Tetrahedron Letters, 24(19), 2025-2028.
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  Abstract: Zeylasteral and desmethylzeylasterone, two new triterpenes from Kokoona zeylanica have been shown to be 2,3-dihydroxy-6,23-dioxo-24-nor-D:A-friedo-oleana-1,3,5(10),7-tetraen-29-oic acid methyl ester (20α) and 2,3-dihydroxy-6-oxo-24-nor-D:A-friedo-oleana-1,3,5(10),7-tetraen23,29-dioic acid (20α), respectively, and have been related to trimethylzeylasterone. A partial synthesis of trimethylzeylasterone starting from pristimerin has been achieved. © 1983.
• Gunaherath, G. B., Gunatilaka, A., Sultanbawa, M. S., & Balasubramaniam, S. (1983). 1,2(3)-Tetrahydro-3,3′-biplumbagin: A naphthalenone and other constituents from Plumbago zeylanica. Phytochemistry, 22(5), 1245-1247.
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  Abstract: The isolation of plumbagin, droserone, isoshinanolone and a new naphthalenone, 1,2(3)-tetrahydro-3,3′-biplumbagin is reported from the phenolic fract. © 1983.
• Gunatilaka, A. A., Sultanbawa, U. S., Wimalasena, K., & Balasubramaniam, S. (1983). Studies on medicinal plants of Sri Lanka. 10. Linarin, a flavone glycoside from exacum macranthum. Planta Medica, 48(1), 61-62.
• Gunatilaka, A. L., Nanayakkara, N. D., & Wazeer, M. I. (1983). ¹³C NMR Spectra of some D:A-friedo-oleananes. Phytochemistry, 22(4), 991-992.
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  Abstract: The 13C NMR signals of D:A-friedo-olean-7-one, putranjivadione, D:A-friedo-olean-22-one, D:A-friedo-olean-3,22-dione, and Salacia triterpene R have been assigned using off-resonance decoupling and lanthanide induced shift techniques. 13C NMR data provide further evidence for the boat-boat conformation for the D and E rings of D:A-friedo-oleananes in solution. © 1983.
• Gunatilaka, A. L., Uvais, M., Sultanbawa, S., Surendrakumar, S., & Somanathan, R. (1983). Structure of a bipyridine alkaloid from Broussonetia zeylanica. Phytochemistry, 22(12), 2847-2850.
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  Abstract: From the benzene extract of the timber of Broussonetia zeylanica, 8-hydroxyquinoline-4-aldehyde, a new alkaloid and two unidentified minor alkaloids have been isolated. The spectroscopic evidence suggested the new alkaloid to be 3,4′-dihydroxy-2,3′-bipyridine. © 1983.
• Gunatilaka, A., Hirai, N., & Kingston, D. G. (1983). Synthesis of racemic fecapentaene-12, a potent mutagen from human feces, and its regioisomer. Tetrahedron Letters, 24(49), 5457-5460.
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  Abstract: Racemic fecapentaene-12 [3-(1,3,5,7,9-dodecapentaenyloxy)-1,2-propanediol (1)] and its regioisomer 2-(1,3,5,7,9-dodecapentaenyloxy)-1,3-propanediol (2) have been synthesized. The latter compound is comparably mutagenic to 1. © 1983.
• Gunatilaka, A., Sriyani, H., Sotheeswaran, S., & Waight, E. S. (1983). 2,5-dihydroxy-1,6-dimethoxyxanthone and biflavonoids of Garcinia thwaitesii. Phytochemistry, 22(1), 233-235.
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  Abstract: The petrol and methanol extracts of the bark and timber of Garcinia thwaitesii have been investigated. In addition to β-amyrin and tirucallol, four biflavonoids and a new xanthone, 2,5-dihydroxy-1,6-dimethoxyxanthone have been isolated and characterized. © 1983.
• Kamal, G. M., Gunaherath, B., & Gunatilaka, A. L. (1983). 23-oxo-isopristimerin III: A new natural phenolic (9+8)-24-nor-d:a-friedo-oleanan triterpene. Tetrahedron Letters, 24(27), 2799-2800.
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  Abstract: The structure of a new natural phenolic (9+8)-24-nor-D:A-friedo-oleanan triterpene isolated from Kokoona zeylanica has been established as 23-oxo-isopristimerin III. © 1983.
• M., G., & A., A. (1983). Studies on terpenoids and steroids. Part 3. Structure and synthesis of a new phenolic D:A-friedo-24-noroleanane triterpenoid, zeylasterone, from Kokoona zeylanica. Journal of the Chemical Society, Perkin Transactions 1, 2845-2850.
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  Abstract: Zeylasterone, the first of a novel series of natural phenolic nortriterpenes from Kokoona zeylanica (Celastraceae) and ' kokum soap ' has been shown to be 29-methyl hydrogen 2,3-dihydroxy-6-oxo-D:A-friedo-24-noroleana-1,3, 5(10),7-tetraene-23,29-dioate (3) on the basis of spectroscopic and chemical evidence. Trimethylzeylasterone (8) has been synthesized from pristimerin, a quinone methide present in K. zeylanica and ' kokum soap '. The biosynthetic importance of some triterpenoids of K. zeylanica is discussed.
• Dissanayake, C. B., Senaratne, A., & Gunatilaka, A. (1982). Organic geochemical studies of the Muthurajawela peat deposit of Sri Lanka. Organic Geochemistry, 4(1), 19-26.
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  Abstract: Organic constituents present in the Muthurajawela peat deposit of Sri Lanka, have been investigated. Here, we report the variations with depth of sitosterol and sitostane (stigmastane), which were found to be major constituents of extracts and, hence, were selected to study the process of diagenesis. These two compounds were present in anomalous concentrations in the middle horizon of the depth profile. Considering the stratigraphy and sterol concentrations, it can be concluded that the middle horizon resulted from a sudden terrestrial input, which could have been due to a Pleistocene or Quaternary environmental change. © 1982.
• Gunatilaka, A. L., Jasmin, A., & Sotheeswaran, S. (1982). Minor xanthones of Hypericum mysorense. Phytochemistry, 21(7), 1751-1753.
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  Abstract: 2-Hydroxyxanthone, 1,7-dihydroxyxanthone, 1-hydroxy-7-methoxyxanthone, 6,7-dimethoxy-1-hydroxyxanthone and a new natural product, 2-hydroxy-3-methoxyxanthone, have been isolated and characterized from the phenolic fraction of the chloroform extract of the timber of Hypericum mysorense. The presence of simple xanthones in this genus supports the classification of Hypericum in the subfamily Hypericoideae in Guttiferae. © 1982.
• Gunatilaka, A. L., Nanayakkara, N. D., Uvais, M., Sultanbawa, S., & Balasubramaniam, S. (1982). Friedelin, D:A-friedo-olean-3,21-dione and 21α-hydroxy-D:A-friedo-olean-3-one from Kokoona zeylanica. Phytochemistry, 21(8), 2061-2063.
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  Abstract: Three triterpenes obtained from the inner bark of Kokoona zeylanica have been identified as friedelin, D:A-friedo-olean-3, 21-dione and 21α-hydroxy- D:A-friedo-olean-3-one by spectroscopic properties and chemical interconversions. Their chemotaxonomic significance is emphasized. © 1982.
• Gunatilaka, A., Silva, A. D., Sotheeswaran, S., & Tillekeratne, L. M. (1982). Horsfieldin, a lignan and other constituents from Horsfieldia iryaghedhi. Phytochemistry, 21(11), 2719-2723.
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  Abstract: A new lignan, horsfieldin [2-(3-hydroxy-4-methoxyphenyl)-6-(3,4-methylenedioxyphenyl)-3,7-dioxabicyclo(3,3,0)octane], d-asarinin, (-)-dihydrocubebin, dodecanoylphloroglucinol, myristic acid, trimyristin and sitosterol have been isolated and characterized from the hot methanol extract of Horsfieldia iryaghedhi seeds. The absolute configuration of the lignans and the chemotaxonomic significance of their occurrence is discussed. © 1982.
• Gunatilaka, A., Sirimanne, S. R., Sotheeswaran, S., & Sriyani, H. (1982). Flavonoids of Gardenia cramerii and G. fosbergii bud exudates. Phytochemistry, 21(3), 805-806.
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  Abstract: From the bud exudates of Gardenia cramerii and G. fosbergii, two species endemic to Sri Lanka, a new flavonoid with an unusual B-ring oxidation pattern, 5,5′-dihydroxy-6,7,2′,3′-tetramethoxyflavone, was characterized. Two other rare flavonoids, 5,3′,5′-trihydroxy-3,6,7,4′-tetramethoxyflavone and 5-hydroxy-6,7,3′,4′,5′-pentamethoxyflavone were also isolated from both Gardenia species. © 1982.
• Gunatilaka, A., Sotheeswaran, S., Sriyani, H., & Waight, E. S. (1982). A revised structure for hermonionic acid. Tetrahedron Letters, 23(29), 2987-2990.
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  Abstract: Hermonionic acid and its decarboxylated product have been isolated from Garcinia quaesita. 13C NMR spectral and chemical evidence indicate that hermonionic acid is 2-0-[2-(3-methylbut-2-enyl)-3-methoxy- 4-hydroxy-5-(3,7-dimethylocta-2,6-dienyl]-4-methoxy-5-(3-methylbut-2-enyl-6-hydroxybenzoic acid. The previously assigned dienone structure for this acid is incorrect. © 1982.
• Herz, J. E., Gunatilaka, A., Sotheeswaran, S., & Torres, J. V. (1982). Esterification of acid chlorides with thallium and potassium salts of 19-norethisterone: Formation of 17-enol esters. Steroids, 40(3), 261-266.
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  PMID: 7184202;Abstract: During the esterification of acid chlorides with thallium and potassium salts of 19-norethisterone, 17-enol esters were isolated. The enol esters are formed Via the intermediate, 4-estrene-3, 17-dione. © 1982.
• Kamal, G. M., Gunaherath, B., A., A., Uvais, M., Sultanbawa, S., & Balasubramaniam, S. (1982). Dulcitol and (-)-4′-O-methylepigallocatechin from Kokoona zeylanica. Journal of Natural Products, 45(2), 140-142.
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  Abstract: A phytochemical investigation of the methanolic extract of the inner root bark of Kokoona zeylanica Thwaites (Celastraceae) has resulted in the isolation and identification of dulcitol and (-)-4′-O-methylepigallocatechin. The chemotaxonomic significance and biological activity of dulcitol are discussed.
• Tillekeratne, L. M., Jayamanne, D. T., Weerasuria, K. D., & Gunatilaka, A. (1982). Lignans of Horsfieldia iryaghedhi. Phytochemistry, 21(2), 476-478.
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  Abstract: A detailed chemical investigation of extracts of the bark, leaf and timber of Horsfieldia iryaghedhi collected in Sri Lanka, led to the isolation of (+)-asarinin, dodecanoylphloroglucinol and (-)-dihydrocubebin. © 1982.
• A., A., Gopichand, Y., Schmitz, F. J., & Djerassi, C. (1981). Minor and trace sterols in marine invertebrates. 26. Isolation and structure elucidation of nine new 5α,8α-epidioxy sterols from four marine organisms. Journal of Organic Chemistry, 46(19), 3860-3866.
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  Abstract: Sixteen 5α,8α-epidioxy Δ6 and Δ6,9(11) sterols, of which nine are new, have been isolated from the marine organisms Ascidia nigra, Dendrogyra cylindrus, Thalysias juniperina, and Aplysia dactylomela by reverse-phase high-performance liquid chromatography and characterized by high-resolution mass spectrometry and 360-MHz proton NMR spectroscopy. Attention is drawn to some unusual concentration-dependent NMR shifts of methyl signals. The probable biological significance of these epidioxy sterols is discussed with special reference to sterol biosynthesis. © 1981 American Chemical Society.
• Arseculeratne, S. N., Gunatilaka, A., & Panabokke, R. G. (1981). Studies on medicinal plants of Sri Lanka: Occurrence of pyrrolizidine alkaloids and hepatotoxic properties in some traditional medicinal herbs. Journal of Ethnopharmacology, 4(2), 159-177.
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  PMID: 7311596;Abstract: There is a paucity of data on the occurrence of hepatotoxic and hepatocarcinogenic pyrrolizidine alkaloids in medicinal plants, and there are no data on the hepatotoxic properties of herbal medicines that are used in the traditional pharmacopoiea of Sri Lanka and other Asian and African countries. In view of the extensive consumption of these herbs and the occurrence of chronic liver diseases including hepatocellular cancer in this and other countries of South Asia, we have screened fifty medicinal plants for pyrrolizidine alkaloids and have obtained positive results with three species, namely Crotalaria verrucosa L., Holarrhena antidysenterica (L.) Br., and Cassia auriculata L. Feeding trials in rats with materials from these three species produced liver lesions - disruption of the centrilobular veins, congestion or haemorrhage in the centrilobular sinusoids, centrilobular or focal hepatocellular necrosis - and histopathology in the lungs and kidneys which were compatible with the action of pyrrolizidine alkaloids. The presence of alkaloids in C. auriculata has not been previously reported nor has the presence of pyrrolizidine alkaloids in H. antidysenterica. It is suggested that the consumption of herbal medicines that contain pyrrólizidine alkaloids could contribute to the high incidence of chronic liver disease including primary hepatocellular cancer in Asian and African countries. © 1981.
• Gunatilaka, A. L., Sotheeswaran, S., Sriyani, B., & Balasubramaniam, S. (1981). Isoboldine and lupenone from Neolitsea fuscata. Planta Medica, 43(3), 309-310.
• Gunatilaka, A., Nanayakkara, N., Uvais, M., & Sultanbawa, S. (1981). Structures of kokzeylanol and kokzeylanonol two new natural tri- and tetra- oxygenated D:A-friedo-oleananes. Tetrahedron Letters, 22(15), 1425-1428.
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  Abstract: Kokzeylanol and kokzeylanonol obtained from Kokoona zeylanica have been shown to be 6β,27-dihydroxy-D:A-friedo-olean-3-one (1) and 6β,27-dihydroxy-D:A-friedo-oleana-3,21-dione (2), respectively by the deoxygenatlon of their 27-acetoxy derivatives using Lithium-ethylene diamine reduction coupled with spectroscopic and irradiation methods. Kokzeylanonol represents the first tetraoxygenated D:A-friedo-oleanane isolated from a natural source. © 1981.
• Gunatilaka, A. A., Sotheeswaran, S., Balasubramaniam, S., Chandrasekara, A. I., & Sriyani, H. T. (1980). Studies on medicinal plants of Sri Lanka. III: Pharmacologically important alkaloids of some Sida species. Planta Medica, 39(1), 66-72.
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  PMID: 7403308;
• Kamal, G. M., Gunaherath, B., Gunatilaka, A. L., Uvais, M., Sultanbawa, S., & Wazeer, M. I. (1980). The structure of zeylasterone - the first of a new series of phenolic 24-nor-D:A-friedo-oleanan triterpenes. Tetrahedron Letters, 21(49), 4749-4752.
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  Abstract: Zeylasterone, a new triterpene from Kokoona zeylanica, is shown to be 2,3-dihydroxy-6-oxo-24-nor-D:A-friedo-oleana-1,3,5(10),7-tetraen-23,29-d ioic acid-29-methyl ester (20 α) (1), the first member of a new series of phenolic 24-nor-D:A-friedo-oleanans. © 1980.
• Gunatilaka, A. L., & Mateos, A. F. (1979). Hydroboration of tricarbonylironergosteryl benzoate. Synthesis of (22R)- and (22S)-3β-benzoyloxyergosta-5,7-dien-22-ol and (23R)-3β- benzoyloxyergosta-5,7-dien-23-ol. Journal of the Chemical Society, Perkin Transactions 1, 935-938.
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  Abstract: Hydration of tricarbonylironergosteryl benzoate via hydroboration and subsequent decomplexing affords a mixture of (22R)- and (22S)-3β- benzoyloxyergosta-5,7-dien-22-ol and (23R)-3β-benzoyloxyergosta-5,7-dien- 23-ol. Oxidation gives 3β-benzoyloxyergosta-5,7-dien-22- and -23-one. On reduction these ketones yield (23S)-3β-benzoyloxyergosta-5,7-dien-23-ol in addition to the above three dienols. Stereochemical assignments are on the basis of molecular rotations.
• Gunatilaka, A. L., Nanayakkara, N. D., & Uvais, M. (1979). Irradiation of friedelan-21-ones: Structure determination of novel friedelane triterpenes from kokoona zeylanica. Journal of the Chemical Society, Chemical Communications, 434-436.
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  Abstract: Formation of the photoproducts (10) and (12) and chemical and spectroscopic evidence suggest that kokoononol obtained from Kokoona zeylanica is 27-hydroxyfriedelane-3,21-dione (1); kokoondiol and kokoonol have been identified as 21α,27-dihydroxyfriedelan-3-one (2) and 27-hydroxyfriedelan- 3-one (3), respectively, by chemical conversions.
• Gunatilaka, A., Balasubramaniam, S., & Kumar, V. (1979). 2,3-Dimethoxyxanthone from Hypericum mysorense. Phytochemistry, 18(1), 182-183.
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  Abstract: Different parts of Hypericum mysorense have been examined for the presence of2,3-dimethoxyxanthone which comprised the major constituent of the timber. Presence of simple xanthones in this genus supports the classification of Hypericum in the subfamily Hypericoideae in Guttiferae. © 1979.
• Gunatilaka, A., Nanayakkara, N., & Sultanbawa, M. S. (1979). Structures of three new 6β-hydroxy di- and tri-oxygenated friedelane triterpenes from kokoona zeylanica thw. (celastraceae). Tetrahedron Letters, 20(19), 1727-1730.
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  Abstract: Three new triterpenes zeylanol, zeylanonol and zeylandiol isolated from Kokoona zeylanica have been identified as 6β-hydroxyfriedelan-3-one, 6β-hydroxyfriedelan-3,21-dione and 6β,21β-dihydroxyfriedelan-3-one, respectively by spectroscopic methods and chemical interconversions. © 1979.
• Gunatilaka, A. L., & Sotheeswaran, S. (1978). Convenient preparation of esters of testosterone and 19-norethisterone with hindered acids. Journal of the Chemical Society, Chemical Communications, 980-981.
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  Abstract: Testosterone and 19-norethisterone are smoothly esterified by some hindered carboxylic acids in pyridine containing benzenesulphonyl chloride.
• Sultanbawa, M. U., Wannigama, G. P., Bandaranayake, W. M., Kumar, V., A., A., Marikar, F. A., Balasubramaniam, S., & Arsecularatne, S. N. (1978). Chemical investigation of ceylonese plants. Part XXIX. A survey of plants of Sri Lanka (Ceylon) for alkaloids I. Journal of Natural Products, 41(6), 597-633.
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  Abstract: Four hundred and sixty-four Sri Lanka plant species, including 170 endemic species, were screened for the occurrence of alkaloids. The plants represented 314 genera and 96 families, of which 49 were tropical families. Extractions were carried out by three different procedures, and the presence of alkaloids was determined by Mayer's test. Tlc of the crude extracts furnished the approximate number of alkaloids. Ninety-one species, inclusive of 27 endemic species, gave a positive Mayer's test. By means of tlc, 417 species were tested with Dragendorff's reagent, and 137 were found to be positive. Of the 214 species tested with iodoplatinate reagent, 89 gave a positive response. Of the alkaloid-containing species, 128, distributed among 42 families, had not been previously reported in the literature, to the best of our knowledge. These included 59 endemic species distributed among 25 families.
• Gunatilaka, A. (1976). Thin-layer chromatography of N-nitrosamines. Journal of Chromatography A, 120(1), 229-233.
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  PMID: 1270550;
• H., D., A., A., Nakanishi, T., Patin, H., Widdowson, D. A., & Worth, B. R. (1976). Synthetic uses of steroidal ring B diene protection: 22,23- dihydroergosterol. Journal of the Chemical Society, Perkin Transactions 1, 821-826.
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  PMID: 944709;Abstract: Protection of the ring B diene system of ergosterol by (i) a two-step addition of the elements of water across the 5,6-double bond, (ii) formation of the 4-phenyl-1,2,4-triazoline-3,5-dione adduct, or (iii) formation of the iron tricarbonyl adduct by treatment with p-methoxybenzylideneacetonetricarbonyliron, allowed selective reduction of the 22,23-double bond by catalytic or, as appropriate, ionic hydrogenation. Regeneration of the 5,7-diene system in each case gave a high yield of 22,23-dihydroergosterol.
• H., D., Bracho, R. D., Gunatilaka, A. L., & Widdowson, D. A. (1975). Phenol oxidation and biosynthesis. Part XXV. New syntheses of bis-(2-arylethyl)amines of biosynthetic importance. Journal of the Chemical Society, Perkin Transactions 1, 579-588.
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  Abstract: Two efficient routes to bis-(2-arylethyl)amines have been developed by using regiospecific alkylation of dialkylnitrosamine anions and homologation of aromatic aldehydes with methoxyacetonitrile anion as the respective key steps. The hitherto uncharacterised 1,3-diaryl-2-azonia-allene ions have been prepared in isolable form. Attempted insertion of C1 fragments into these systems as a third route to the title compounds failed.
• H., D., Gunatilaka, A. L., Jarman, T. R., Widdowson, D. A., Bard, M., & Woods, R. A. (1975). Biosynthesis of terpenes and steroids. Part X. The sterois of some yeast mutants doubly defective in ergosterol biosynthesis. Journal of the Chemical Society, Perkin Transactions 1, 88-92.
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  PMID: 1094026;Abstract: The sterols of six double mutants of Saccharomyces cerevisiae have been isolated and characterised, and the sterol distribution has been related to the biosynthetic pathway from zymosterol to ergosterol. Hitherto unknown ergosta-5,8-dien-3β-ol and cholesta-7,24-dien-3β-ol have been isolated and characterised.
• Jarman, T. R., Gunatilaka, A., & Widdowson, D. A. (1975). Investigations on the biosynthesis of steroids and terpenoids. XI. The 24-methylene sterol 24(28)-reductase of Saccharomyces cerevisiae. Bioorganic Chemistry, 4(2), 202-211.
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  Abstract: The microsomal fraction of Saccharomyces cerevisiae has been shown to catalyse the NADPH-dependent reduction of ergosta-5,7,22,24(28)-tetraen-3β-ol to ergosterol. This cell-free system together with whole-cell cultures of polyene-resistant mutants has been used to compare the rates of reduction of other 24-methylene sterols. The results indicate that the enzyme involved exhibits a marked specificity for ergosta-5,7,22,24(28)-tetraen-3β-ol and support the concept of a major terminal step in ergosterol biosynthesis. © 1975.
• A., A., & Uvais, M. (1973). Chemical investigation of ceylonese plants. Part III. Extractives of the fruits of argyreia populifolia choisy (Convolvulaceae). Journal of the Chemical Society, Perkin Transactions 1, 1155-1157.
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  Abstract: From the light petroleum extractives of the fruits of Argyreia populifolia Choisy, friedelin, friedelan-3β-ol, octacosan1-ol, β-sitosterol, a new ester [stearyl 4-hydroxycinnamate (I)], and an unidentified ester have been isolated. Stearyl 4-methoxycinnamate (II) has been synthesised and shown to be identical with the methyl ether of the natural ester (I).
• H., D., A., A., Letcher, R. M., M., A., & Widdowson, D. A. (1973). Phenol oxidation and biosynthesis. Part XXII. The alkaloids of erythrina lysistemon, E. abyssinica, E. poeppigiana, E. fusca, and E. lithosperma; the structure of erythratidine. Journal of the Chemical Society, Perkin Transactions 1, 874-880.
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  Abstract: Erythrina lysistemon, E. abyssinica, E. poeppigiana, E. fusca, and E. lithosperma have been examined for alkaloids of biogenetic interest. In addition to the known Erythrina alkaloids, α- and β-erythroidine, eryosdine, erythraline, erythratine, and erysotrine, new alkaloids erythristemine, erythratidinone, and 3-demethoxyerythratidinone were isolated and characterised. The aporphine alkaloid isoboldine, and the benzyltetrahydroisoquinoline alkaloids (-)-orientaline and (+)-N-nororientaline were also isolated. A partial synthesis of erythratidine indicated a 2S configuration. A plausible biogenetic scheme for the new alkaloids is discussed. © Copyright 1973 by The Chemical Society.

Presentations

• Gunatilaka, L. (2022, November). Natural Products Research: Opportunities and Challenges. Invited Seminar, University of Geneva. University of Geneva, Switzerland.
• Gunatilaka, L., Cuendet, M., & Vérièpe-Salarno, J. (2022, October). A withanolide derivative as modulator of autophagy in multiple myeloma. Swiss Cancer Center Leman Annual Retreat. Geneva, Switzerland: University of Geneva.
• Gunatilaka, L. (2019, April). Discovery and Development of Natural Products-Based Potential Therapeutics for Prostate Cancer and Melanoma. Research Seminar. Blacksburg, Virginia: Virginia Tech.
• Gunatilaka, L. (2019, February). Anticancer Potential of 17beta-Hydroxywithanolides (17-BHWs) in Prostate Cancer. Research Seminar. Baroda, India: Sun Pharma Advanced Research Company.
• Gunatilaka, L. (2019, February). Discovery and Development ofNatural Product-Based Drugs: Opportunities and Challenges. Research Seminar. Baroda, India: Sun Pharma Advanced Research Company.
• Gunatilaka, L. (2019, July). Discovery of Natural Products-Based Anticancer & Other Bioactive Agents From Plants and Symbiotic Fungi. Research Seminar. Shandong, PR China: Shandong University.
• Gunatilaka, L. (2019, July). Discovery of Natural Products-Based Anticancer & Other Bioactive Agents From Plants and Symbiotic Fungi. Research Seminar. Xuzhou, PR China: The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, Jiangsu Normal University.
• Gunatilaka, L. (2019, July). Traditional Medicine-Inspired Drug Discovery for Some Modern Day Diseases. Research Seminar. Xi'an, PR China: North Western University.
• Gunatilaka, L. (2019, July). Withanolides as Potential Natural Product-Based Drugs to Treat Cancer and Neurodegenerative Diseases. Research Seminar. Nanjing, PR China: China Pharmaceutical University.
• Gunatilaka, L. (2019, June). Discovery of Anticancer Drugs from Plants Used in Traditional Medicine. The 10th International Conference on TCM Pharmaceutical Analysis &Annual Meeting & Election of the Council of Specialty Committee of TCM Pharmaceutical Analysis. Shanghai, PR China: World Federation of Chinese Medicine Societies.
• Gunatilaka, L. (2019, March). From Plants to Pharmacy Shelf: Discovery & Development of Potential Therapeutics for Prostate Cancer. Research Seminar. Colombo, Sri Lanka: Link Natural Products Inc..
• Gunatilaka, L. (2019, March). Natural Product Research: Opportunities and Challenges. Research Seminar. Peradeniya, Sri Lanka: University of Peradeniya.
• Gunatilaka, L., de Amorim, M., Wijeratne, K., Batista, J., & dos Santos, L. (2019, September). An epigenetic modifier induces the production of new metabolites by Aspergillus terreus AST0006. 67th International Congress and Annual Meeting of the Society for Medicinal Plant and Natural Product Research. Innsbruck, Austria: European Society of Pharmacognosy.
• Gunatilaka, L. (2017, November). Annonalide and Derivatives: Semi-synthesis, Antiproliferative Activities and Studies of Annonalide-DNA Interactions. Sixth Brazilian Conference on Natural Products. Vitoria, Brazil: Brazilian Chemical Society.
• Gunatilaka, L. (2016, May). Withanolides – a Class of Plant-Based Natural Products – as Potential Drugs for Some Modern Day Diseases. Research Seminar. Deartment of Chemistry, University of Sao Paulo, Brazil.
• Gunatilaka, L. (2016, October). "Cool" Molecules from "Hot" Deserts, A Tale of Significant Findings. Research Seminar. CEAC, University of Arizona, Tucson.
• Gunatilaka, L. (2015, February). Life Saving Plants – Mother Natures’ Gifts to the Man. Seminar. Tucson, Arizona: Plant Sciences Undergraduate Student Club.
• Gunatilaka, L. (2015, February). Traditional Knowledge Inspired Discovery of Natural Product-Based Therapeutics for Cancer & Neurological Disorders. Research Seminar. Phoenix, Arizona: Translational Genomics Institute (TGen).
• Gunatilaka, L. (2015, July). Exploring Plant & Lichen-Associated Microbial Diversity for Discovery of Small-Molecule Bioactive Agents. American Society of Pharmacognosy Annual Meeting. Copper Mountain, Colorado: American Society of Pharmacognosy.
• Gunatilaka, L. (2015, May). Withanolides, A Class of Steroidal Lactones, as Potential Drugs for Cancer & Neurodegenerative Disorders. Research Seminar. Sao Paulo, Brazil: University of Sao Paulo, Brazil.
• Gunatilaka, L. (2015, November). Natural Products-Based Discovery of Drugs for Cancer and Neurodegenerative Diseases. Invited Research Seminar. Geneva, Switzerland: University of Geneva.
• Gunatilaka, L. (2015, September). Accessing Plant & Lichen-Associated Microbial Diversity for Bioactive Metabolites. Invited Research Seminar. Dortmund, Germany: Technical University of Dortmund.
• Gunatilaka, L. (2015, September). Traditional Medicine Inspired Drug Discovery for Some Modern Day Diseases. Research Seminar. London, England: London School of Pharmacy.
• Gunatilaka, L. (2014, August). Withanolides as Potential Drugs for Cancer & Neurodegenerative Disorders. Research Seminar. Bethesda, Maryland, USA: National Cancer Institute.
• Gunatilaka, L. (2014, December). Natural Products from Microbial (Endo)symbionts: Occurrence & Significance. Symposium on Bioprospection of Marine Natural Products. Fortaleza, Brazil: University of Ceara.
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  Invited Lecture
• Gunatilaka, L. (2014, December). Natural Products-Based Discovery & Development Through Multidisciplinary Collaboration & Innovation. Research Seminar. Fortaleza, Brazil: Postgraduate Program of University of Ceara.
• Gunatilaka, L. (2014, July). Discovery & Development of Natural Products-Based Drugs Through Multidisciplinary Collaboration and Innovation. Public Lecture. Colombo, Sri Lanka: National Science Foundation, Sri Lanka.
• Gunatilaka, L. (2014, July). Some Innovative Strategies for Natural Products Research. Research Seminar. Shanghai, China: Shanghai Institute of Materia Medica.
• Gunatilaka, L. (2014, May 19th). Natural Products Discovery & Development at UA-NPC: An Overview. Research Seminar. Fortaleza, Brazil: Department of Chemistry, University of Ceara.
• Gunatilaka, L. (2014, May 9th). Withanolides as Potential Drugs to Treat Cancer and Neurodegenerative Disorders: Structure-Activity Relationships. Research Seminar. Fortaleza, Brazil: Department of Pharmacology, University of Ceara.
• Gunatilaka, L. (2014, October). Natural Products of Agricultural and Medicinal Value from Plants and “Bugs” of Arid Environments. Research Seminar. University of Arizona: School of Natural Resources & the Environment.
• Gunatilaka, L. (2014, October). Traditional Knowledge Inspired Discovery of Natural Product-Based Therapeutics for Cancer & Neurological Disorders. 46th Brazilian Congress of Pharmacology & Experimental Therapeutics. Fortaleza, Brazil: Brazilian Society of Pharmacology & Experimental Therapeutics.
• Gunatilaka, L. (2014, September). Studies on Constituents of Indian Ginseng: A Dietary Supplement and Panacea for Some Modern Day Diseases. Research Seminar. University of Arizona: Department of Nutritional Sciences.
• Gunatilaka, L. (2014, September). Traditional Medicine Inspired (Anticancer) Drug Discovery. Research Seminar. University of Arizona: Cancer Biology Program.
• Gunatilaka, L. -. (2013, July). Harnessing Natural Product Resources for (Drug) Discovery & Development: Some Innovative Strategies. Sao Paulo Advanced School on Bioorganic Chemistry. Sao Paulo, Brazil: FAPESP.
• Gunatilaka, L. -. (2013, October). Traditional Medicine Inspired Drug Discovery for Some Modern Day Diseases. American Chemical Society 44th Western Regional Meeting. Santa Clara, Califormia: American Chemical Society.

Poster Presentations

• Gunatilaka, L., Cuendet, M., & Ferro, A. (2022, October). Withanolide analogs as anti-proliferative compounds in various cancer cell types. Swiss Cancer Center Leman Annual Retreat. Geneva, Switzerland: University of Geneva.
• Gunatilaka, L., Macy, A., Adams, A., Castro-Ochoa, K., Wijeratne, K., Xu, Y., Liu, M. X., Charos, A., Bosenberg, M., Sertil, A., & Hastings, K. T. (2022, February). Natural Product-Based Induction of Cancer Cell Death Combined with Immunotherapy for Melanoma Treatment. Sixth Annual Arizona Biomedical Research Commission – Flinn Research Conference. Phoenix, AZ: Arizona Biomedical Research Commission and Flinn Foundation.
• Gunatilaka, L., Sertil, A., Castro-Ochoa, K., Wijeratne, K., Xu, Y., Liu, M. X., Adams, A., Macy, A., Kang, P., Charos, A., Bosenberg, M., & Hastings, K. T. (2021, April). Natural Product-Based Induction of Cancer Cell Death Combined with Immunotherapy for Melanoma Treatment. Arizona Biomedical Center/Flinn Foundation Annual Conference. Phoenix, AZ: Arizona Biomedical Center/Flinn Foundation.
• Gunatilaka, L., Wijeratne, E. M., Xu, Y., Liu, M. X., Inacio, M. C., Brooks, A. D., Tewary, P., & Sayers, T. J. (2021, October). Ring A/B-modified analogues of physachenolide C as antiproliferative agents for prostate cancer. Rocky Mountain Regional Meeting. Tucson, AZ: American Chemical Society.
• Gunatilaka, L., Xu, Y., Wijeratne, E. M., Liu, M. X., Inacio, M. C., Ranjbar, F., Snitkin, E., Xuan, L., & Wang, W. (2021, October). Natural products-based anticancer drug discovery: New cytotoxic withanolides from Physalis coztomatl. Rocky Mountain Regional Meeting. Tucson, AZ: American Chemical Society.
• Gunatilaka, L., Sayers, T., Hastings, K., Sertil, A., Tewary, P., Wijeratne, K., Xu, Y., Liu, M., Macy, A., & Brooks, A. (2020, February). Natural products-based induction of cancer cell death combined with immunotherapy for melanoma treatment.. Fifth Annual Arizona Biomedical Research Commission – Flinn Research Conference. Phoenix, AZ: Arizona Biomedical Research Center.
• Gunatilaka, L., Sayers, T., Xu, Y., Wijeratne, K., Brooks, A., & Tewary, P. (2019, March). Natural Products-Based Induction of Cancer Cell Death Combined with Immunotherapy for Melanoma Treatment. Arizona Biomedical Research Center Conference. Phoenix, Arizona: Arizona Department of Health Services.
• Gunatilaka, L., Brooks, A. D., Xu, Y., Wijeratne, K., Tewary, P., Henrich, C. J., Thomas, C. L., & Sayers, T. J. (2016, April). Promoting TRAIL apoptosis signaling using 17-beta-hydroxywithanolides. American Association for Cancer Research Annual Meeting. New Orleans, Louisiana: American Association for Cancer Research.
• Gunatilaka, L., Issa, M. E., Barta, S., Monteillier, A., Wijeratne, K., & Cuendet, M. (2016, August). The In Vitro Cytotoxic Effect of Withanolides in Multiple Myeloma Cancer Stem Cells and Tumoral Cells. Ninth Swiss Pharma Science Day. University of Bern, Bern, Switzerland: Swiss Academy of Pharmaceutical Sciences.
• Gunatilaka, L., Wijeratne, E. K., Bashyal, B. P., U’Ren, J. M., Arnold, A. E., Tan, W., Zhang, D., & Chapman, E. (2015, October). Geopyxins A–F, Six New Tetracyclic ent-Kaurane Diterpenoids from Endolichenic Fungal Strains Geopyxis aff. majalis and Geopyxis sp. AZ0066. CALS Poster Session. Tucson, Arizona: College of Agriculture & Life Sciences.
• Gunatilaka, L., Xu, Y., Bunting, D. P., Liu, M. X., & Bandaranayake, H. A. (2015, October). Withanolides from Aeroponically Grown Physalis crassifolia (Yellow Nightshade Ground Cherry) and Their Potent and Selective Cytotoxicity for Prostate Cancer Cells. CALS Poster Forum. Tucson, Arizona: College of Agriculture & Life Sciences.

Reviews

• Gunatilaka, L., & Padumadasa, C. (2017. Review of the Book Medicinal and Aromatic Plants – Industrial Profiles. Volume 48: Sesame, The genus Sesamum. Edited by D. Bedigian (Missouri Botanical Garden, St. Louis, Missouri). CRC Press, Taylor & Francis Group: Boca Raton, FL. 2011. xxiii + 532 pp. 18 x 26 cm. $159.95. ISBN 978-0-8493-3538-9 (Hardback).(pp 230-231).