Cytotoxic 19,20-epoxycytochalasans from endophytic fungus Xylaria cf. curta

Nine new 19,20-epoxycytochalasans (1–9) were isolated from the rice fermentation extracts of endophytic fungus Xylaria cf. curta, along with four known compounds 19,20-epoxycytochalasin C (10), 18-desoxy-19,20-epoxycytochalasin C (11), 19,20-epoxycytochalasin D (12) and 5,6-dihydro-7-oxo-19,20-epoxycytochalasin C (13). Their structures and absolute configurations were determined by 1D and 2D NMR, HRESIMS, X-ray diffraction and ECD calculation. The cytotoxicity of obtained compounds (1−13) was evaluated against human cancer cell lines HL-60, A549, SMMC-7721, MCF-7, and SW480. Remarkably, compound 10 showed significant specific cytotoxicity against HL-60 cell lines with IC50 value of 1.11 μM.