Kaurane-type diterpene glycoside from the stem bark of Acanthopanax trifoliatus

A new diterpene glycoside, acantrifoside D ( 1), as well as three known diterpenes (2 - 4) were isolated from the stem bark of Acanthopanax trifoliatus from Vietnam. Based on 1D and 2D NMR spectroscopic data, their chemical structures were determined to be 16alpha,17-dihydroxy- ent-kauran-19-oic acid 16- O-beta- D-glucopyranoside 19- O-beta- D-glucopyranosyl ester (1), 16alpha H,17-isovalerate- ent-kauran-19-oic acid (2), ent-kaur-16-en-19-oic acid ( 3), and ent-pimara-8(14),15-dien-19-oic acid (4). Compounds 2 - 4 had strong inhibitory effects against COX-1 in an in vitro assay, with IC50 values of 0.21, 0.15 and 0.19 mM, respectively.