Cytotoxic and anti-HIV-1 constituents of Gardenia obtusifolia and their modified compounds

5α-Cycloart-24-ene-3,23-dione (), 5α-cycloart-24-ene-3,16,23-trione () and methyl 3,4-seco-cycloart-4(28),24-diene-29-hydroxy-23-oxo-3-oate (), together with five known flavones 5,7,4′-trihydroxy-3,8-dimethoxyflavone (), 5,7,4′-trihydroxy-3,8,3′-tri-methoxyflavone (), 5,7,4′-trihydroxy-3,6,8-trimethoxyflavone (), 5,4′-dihydroxy-3,6,7,8-tetramethoxyflavone () and 5,3′-dihydroxy-3,6,7,8,4′-pentamethoxyflavone () have been isolated from the leaves and twigs of Gardenia obtusifolia. The structures were assigned on the basis of spectroscopic methods. Compounds and some of the modified compounds showed significant cytotoxic activities in several mammalian cell lines, especially and its diacetate which exhibited potent cytotoxicities (compound : P-388 0.05 μg/mL, KB 0.09 μg/mL, BCA-1 0.63 μg/mL, Lu-1 0.09 μg/mL, ASK 0.70 μg/mL; its diacetate: P-388 0.27 μg/mL, KB 0.06 μg/mL, BCA-1 0.53 μg/mL, Lu-1 0.49 μg/mL). It was also found that , and showed antimitotic acitivity in the ASK assay. Compounds , , , and some of the modified compounds displayed interesting anti-HIV activity in the syncytium assay, but were inactive or exhibited weak activity in the HIV-1 RT assay; while compound was found to be active in the HIV-1 RT assay (99.9 % inhibition at 200 μg/mL), but cytotoxic in the syncytium assay.