Isolation, Structure Determination, In Vivo/Vitro Assay and Docking Study of a Xanthone with antitumor activity from Fungus Penicillium oxalicum

Investigation of EtOAc extract from the fermentation broth of the fungus Penicillium oxalicum led to the isolation of a xanthone, secalonic acid D, which showed good antitumor activity both in vivo and in vitro. The docking study revealed that secalonic acid D could block the active pocket of topoisomerase І with seven hydrogen bonds between secalonic acid D and ARG488, LYS532, ASP533.