Cytotoxic xanthones from the plant endophytic fungusPaecilamycessp. TE-540

One new xanthone, chryxanthone C (1), together with four known analogues (2-5), were isolated from the cultures ofPaecilamycessp. TE-540, an endophytic fungus obtained from the leaves ofNicotiana tabacumL. The structure of1was elucidated by comprehensive spectral analysis including HRESIMS and 1D/2D NMR, which were confirmed by Cu K alpha X-ray crystallography. Compound1featured an unusual dihydropyran ring fused to an aromatic ring, rather than the commonly occurring prenyl moiety. The cytotoxicity of compounds1-5were evaluated against five human tumour cell lines and4exhibited moderate to strong cytotoxicities with IC(50)values ranging from 5.6 to 14.2 mu M.