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/CH2Cl2 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 IC50 values from 0.5 to 6.7 μM against all tested tumor cell lines.