Polyisoprenylated benzophenones and an unusual polyisoprenylated tetracyclic xanthone from the fruits of Garcinia cambogia

In light of the wide range of biological activities of garcinol and with the aim of exploring some of them, we carried out its isolation from the fruits of Garcinia cambogia L. (Guttiferae). Surprisingly, the fruits were also found to contain guttiferones I, J, and K, compounds never reported in G. cambogia, along with three new compounds, namely, guttiferone M (1), guttiferone N (2), and the oxidized derivative of guttiferone K (6). Oxy-guttiferone K (6) is the first example of tetracyclic xanthone derived from the oxidation of a polyisoprenylated benzophenone from natural source. The natural formation of oxy-guttiferone K is in agreement with the previously described cyclization of garcinol by DPPH.