... ) -1,3,6-trihydroxyxanthone (mangostingone) (2), together with 12 known xanthones, cudraxanthone G (3), 8-deoxygartanin (4), garcimangosone ... alpha-mangostin (10), gamma-mangostin (11), mangostinone (12), smeathxanthone A (13), and tovophyllin A (14). The structures of compounds 1 ... 8, 10, 11, and 13 were the most active. Alpha-mangostin (10) inhibited 7,12-dimethylbenz [alpha] anthracene-induced ...