A new polyisoprenylated benzophenone, guttiferone I, together with the known compounds cambogin, 1,7-dihydroxyxanthone, 1,3,6,7-tetrahydroxyxanthone and 1,3,5,6-tetrahydroxyxanthone were isolated from the stem bark of Garcinia griffithii. The acetone extract of the heartwood of Garcinia mangostana