Chemical constituents of Calophyllum brasiliensis: structure elucidation of seven new xanthones and their cancer chemopreventive activity.

The first study of chemical constituents of the stem bark of Calophyllum brasilienses collected in Brazil has led to the isolation and identification of seven new xanthones named brasixanthones A (1), B (4), C (5), D (6), E (2), F (3), and G (10), together with 10 known xanthones. Among the xanthones isolated in this study, 4, 5, 6, and 11 were found to exhibit significant inhibitory activity against 12-O-tetradecanoylphorbol-13-acetate induced Epstein-Barr virus early antigen activation in Raji cells.