Dihydroxanthenones from the fermentation product of an endophytic fungus Gliomastix murorum

Three new dihydroxanthones, muroxanthenones A-C (1-3), together with three known dihydroxanthones (4-6) were isolated from the fermentation products of an endophytic fungus Gliomastix murorum. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compound 3 showed high cytotoxicities against NB4 and PC3 cell with IC50 values of 2.2 and 2.8 mu M. The other compounds also showed moderate cytotoxicities for some tested cell lines with IC50 values between 4.1 and 9.5 mu M.