... rats in the late 1970s, and 1,3,6,7- tetrahydroxy- 2,8-bis (3-methyl-2-butenyl) -9H -xanthen -9-one ... G (1) and 7-methoxy-2- (3-methyl-2-butenyl)-8 -(3-methyl-2-oxo-3- butenyl) -1,3,6-trihydroxyxanthone (mangostingone) (2), together with ... 12 known xanthones, cudraxanthone G (3), 8-deoxygartanin ...