Xanthone derivatives from the fermentation products of an endophytic fungus Phomopsis sp.

Three new xanthones, 1-hydroxy-3-hydroxyethyl-5-methoxy-6-methoxycarbonylxanthone (1), 1,4-dihydroxy-3-hydroxyethyl-5-methoxy-6-methoxydarbonyl-xanthone (2), and 1-hydroxy-3-hydroxyethyl-4-methoxy-8-methoxycarbonylxanthone (3), together with five known xanthones (4-8) were isolated from the fermentation products of an endophytic fungus Phomopsis sp.. Their structures were elucidated by spectroscopic methods including extensive 1D- and 2D-NMR spectroscopic techniques. Compounds 1-3 and 7 were also tested for their cytotoxicity against five human tumor cell lines (NB4, A549, SHSY5Y, PC3, and MCF7) by the MTT method, with paclitaxel used as the positive control. Compound 1 showed cytotoxicity against A549 and PC3 cells with IC50 values of 3.2 and 2.5 mu M, respectively, 2 showed potential cytotoxicity against NB4 cells, with an IC50 value of 3.6 mu M, and 3 showed cytotoxicity against A549 cells with an IC50 value of 3.5 mu M.