Fifteen compounds, namely three new cytochalasans, one new sesquiterpenoid, two new amides, eight known cytochalasans, and one known amide, were isolated from the rice medium fermented by a soil fungus Xylaria sp. Y01. The structures of these compounds were determined through comprehensive analyses of their extensive spectroscopic data, along with quantum chemical calculations. In vitro cytotoxicity assays, we selected three cancer cell lines (HCT116, 4T1, and MHCC97H) and one normal human gastric epithelial GES-1 cell line to explore their potential as anticancer agents. As a result, 6,7-dihydro-7-oxo-cytochalasin C, 5,6-dihydro-7-oxo-19,20-epoxycytochalasin C, 19,20-epoxycytochalasin D, and 19‑epi-cytochalasin P1 showed cytotoxicity against GES-1, while only 19,20-epoxycytochalasin D also exhibited cytotoxicity against 4T1. Our findings further enrich the structural diversity of secondary metabolites from Xylaria species and provide clues for exploring their anticancer potential.
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