Cytotoxic Prenylated Xanthones from the Young Fruit of Garcinia mangostana

Three new prenylated xanthones, mangostenones C (1), D (2), and E (3), together with 16 known xanthones 4—19, were isolated from the young fruit (7-week maturity stage) of Garcinia mangostana. The structural elucidation of the new compounds was mainly established on the basis of 1D and 2D NMR and HR-MS spectroscopic analysis. Compound 1 showed cytotoxic properties against three human cancer cell lines, epidermoid carcinoma of the mouth (KB), breast cancer (BC-1), and small cell lung cancer (NCI-H187), with IC50 values of 2.8, 3.53, and 3.72 μg/ml, respectively. Among the isolates, α-mangostin (12), the major metabolite, exhibited the most potent effects against the BC-1 cells with an IC50 value of 0.92 μg/ml, an activity greater than that of the standard drug ellipticine (IC50=1.46 μg/ml). Compound 12 also showed the highest activity against KB cells, while gartanin (10) displayed the strongest activity against the NCI-H187 cells at the respective IC50 values of 2.08 μg/ml and 1.08 μg/ml.