Caged Xanthones and Biphenyls Isolated from the Tropical Plant Garcinia lateriflora .

Four cytotoxic heptacyclic caged-xanthones [gambogefic acids B-E ( 1 - 4 )], a cytotoxic hexacyclic caged-xanthone [garcilatelic acid ( 5 )], and four biphenyl derivatives [garcilatelibiphenyls A-D ( 6 - 9 )] were newly isolated in a phytochemical study of a 50% MeOH/CH ₂ Cl ₂ extract of Garcinia lateriflora (Clusiaceae). The isolated compounds were evaluated for antiproliferative activity against five human tumor cell lines including a vincristine-resistant line. The new caged-xanthones displayed potent activity with IC ₅₀ values from 0.5 to 6.7 μM against all tested tumor cell lines.