Lithocarpins A–D: four tenellone-macrolide conjugated [4 + 2] hetero-adducts from the deep-sea derived fungus Phomopsis lithocarpus FS508

Jianlin Xu, Haibo Tan, Yuchan Chen, Saini Li, Zilei Huang, Heng Guo, Haohua Li, Xiaoxia Gao, Hongxin Liu, Weimin Zhang

Index: 10.1039/C8QO00095F

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Abstract

Lithocarpins A–D (1–4), the first examples of highly oxygenated tenellone-macrolide conjugated dimers, were isolated from the deep-sea derived fungus Phomopsis lithocarpus FS508. Their structures were elucidated by extensive spectroscopic analyses and X-ray diffraction techniques. Their plausible biogenetic pathways suggested a very intriguing and unusual [4 + 2] cycloaddition with an isobenzofuran as an electron-donating diene. Lithocarpins C and D exhibited a moderate inhibitory effect against three tumor cell lines with IC50 values ranging from 17.0 to 21.6 μM.