Anti-HIV and cytotoxic biphenyls, benzophenones and xanthones from stems, leaves and twigs of Garcinia speciosa

Eleven previously undescribed compounds, including four benzophenones (garciosones A−D), four xanthones (garciosones E−H) and three biphenyls (garciosines A−C), along with eighteen known compounds were isolated from the stems, leaves and twigs of Garcinia speciosa Wall. (Clusiaceae). Their structures were established by extensive spectroscopic analysis. For garciosines A−C, the structures were confirmed by single crystal X-ray diffraction analysis. Most of the isolated compounds were evaluated for their cytotoxic activity and anti-HIV-1 activity using the syncytium inhibition assay and HIV-1 reverse transcriptase (RT) assay. The known compounds, 4,6,3′,4′-tetrahydroxy-2-methoxybenzophenone and macluraxanthone, displayed significant cytotoxic activity with the ED50 in the range of 1.85–11.76 μM. 1,5-Dihydroxyxanthone exhibited the most potent anti-HIV activity against syncytium formation with EC50 < 17.13 μM (SI > 25.28) and 2-(3,3-dimethylallyl)-1,3,7-trihydroxyxanthone was the most active compound in the HIV-1 reverse transcriptase assay with IC50 value of 58.24 μM. Structure-activity relationship of some isolated compounds were also discussed.