Biotransformation of α-mangostin by Colletotrichum sp. MT02 and Phomopsis euphorbiae K12

The microbial transformation of the major mangosteen pericarp xanthone, α-mangostin (1) by the endophytic fungi Colletotrichum sp. MT02 and Phomopsis euphorbiae K12 resulted in the production of the five metabolites 2–6. Biotransformation with Colletotrichum sp. MT02 converted 1 into 17,18-dihydroxymangostanin (2) and cyclomangostanin (3), while incubation with P. euphorbiae K12 gave 12,13,20-trihydroxymangostin (4), 12,13,19-trihydroxymangostin (5), and 20-hydroxymangostanin (6) as transformation products. The structures of these metabolites were elucidated via spectroscopic analyses, and for compound 3, the structure was confirmed by X-ray crystallographic analysis. All metabolites are new, and metabolite 3 possessed an unusual structure of bis-ring fused xanthene in nature. In addition, substrate and all products were evaluated for the antimycobacterial activity against Mycobacterium tuberculosis as well as the cytotoxicity against breast cancer (MCF-7) cell lines.