Cytotoxic constituents of the twigs and leaves of Aglaia rubiginosa

Activity-guided fractionation of a CHCl3-soluble extract of the twigs of Aglaia rubiginosa, using human oral epidermoid carcinoma (KB) cells as a monitor, led to the isolation of a new naturally occurring cyclopenta[b]benzofuran, 1-O-acetylrocaglaol (1), along with seven known compounds, methyl rocaglate (2), rocagloic acid (3), 1-O-acetylmethyl rocaglate (4), desyclamide, eryodictiol, 5-hydroxy-3,7,4'-trimethoxyflavone, and naringenin. A CHCl3 extract of the leaves of A. rubiginosa yielded the new compound (3S,4R,22R)-cholest-7,24-diene-3,4,22-triol (5), as well as 11 known compounds, including 2 and 4 and cabraleone, dammarelonic acid, (20S, 23E)-20,25-dihydroxy-3,4-secodammara-4(28),23-dienoic acid, (20S, 23E)-20,25-dihydroxy-3,4-secodammara-4(28),23-dienoic acid methyl ester, (3,4,22R)-ergosta-5,24(24')-diene-3,4,22-triol, ocotillone, shoreic acid, beta-sitosterol, and beta-sitosterol glycoside. The structures of 1 and 5 were elucidated by spectral and chemical methods. Isolates were evaluated with a human cancer cell panel, and compounds 1-4 were found to exhibit potent cytotoxic activity.