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Tetramic Acids and Pyridone Alkaloids from the Endolichenic Fungus Tolypocladium cylindrosporum
- Li, Xiao-Bin, Li, Lin, Zhu, Rong-Xiu, Li, Wei, Chang, Wen-Qiang, Zhang, Lu-Lu, Wang, Xiao-Ning, Zhao, Zun-Tian, Lou, Hong-Xiang
- Journal of natural products 2015 v.78 no.9 pp. 2155-2160
- Tolypocladium cylindrosporum, X-ray diffraction, acids, alkaloids, apoptosis, bioassays, cell cycle checkpoints, coumarin, cytotoxicity, fungi, humans, lichens, neoplasm cells, neoplasms, spectral analysis
- Three new tetramic acid derivatives, tolypocladenols A₁, A₂, and B (1–3), a new pyridone alkaloid, tolypyridone A (4), and a new coumarin derivative, 3,8-dihydroxy-4-(4-hydroxyphenyl)-6-methylcoumarin (5), together with four known compounds (6–9) were isolated from the endolichenic fungus Tolypocladium cylindrosporum, which inhabits the lichen Lethariella zahlbruckneri. Structures of these compounds were determined by comprehensive analysis of spectroscopic data and single-crystal X-ray diffraction determination. Bioassay of the isolated compounds found that pyridoxatin (7) was cytotoxic to human cancer cells by induction of G0/G1 cell cycle arrest and apoptosis.