2 NEW ISOFLAVONES FROM CEIBA-PENTANDRA AND THEIR EFFECT ON CYCLOOXYGENASE-CATALYZED PROSTAGLANDIN BIOSYNTHESIS

The new isoflavone glucoside vavain 3'-O-beta-D-glucoside (1) and its aglycon, vavain (2), were isolated from the bark of Ceiba pentandra, t ogether with the known flavan-3-ol, (+)-catechin. These novel structur es were elucidated by one-and two-dimensional NMR experiments and by M S, IR, and UV spectroscopy as 5-hydroxy-7,4',5'-trimethoxyisoflavone 3 '-O-beta-D-glucoside (1) and 5,3'-dihydroxy-7,4',5'-trimethoxyisoflavo ne (2), respectively. The compounds were isolated following bioactivit y-directed fractionation, using a cyclooxygenase-1-catalyzed prostagla ndin biosynthesis assay in vitro, in which compounds 1 and 2 and (+)-c atechin exhibited IC50 values of 381, 97, and 80 mu M, respectively (s tandard: indomethacin, IC50 1.1 mu M). When further tested for their i nhibitory effects on cyclooxygenase-2-catalyzed prostaglandin biosynth esis, 1 and 2 were found to be inactive (IC50 > 1200 and >900 mu M, re spectively).