Inhibitory constituents against cyclooxygenases from Aralia cordata Thunb.

Seven diterpenes, four polyacetylenes, a lipid glycerol, and two sterols were isolated from the methylene chloride fraction of the root of Aralia cordata. Their chemical structures were determined as (-)-pimara-8(14),15-dien-19-oic acid (2), pimaric acid (3), (-)-kaur-16-en-19-oic acid (4), 17-hydroxy-ent-kaur-15-en-19-oic acid (9), 7alpha-hydroxy-(-)-pimara-8(14),15-dien-19-oic acid (10), 16alpha,17-dihydroxy-(-)-kauran-19-oic acid (11), 16-hydroxy-17-isovaleroyloxy-ent-kauran-19-oic acid (12), falcarindiol (5), dehydrofalcarindiol (6), dehydrofalcarindiol-8-acetate (7), falcarindiol-8-acetate (8), alpha-mono palmitin (13), stigmasterol (1), and daucosterol (14) by the spectral evidences. These compounds were tested with COX-1 and COX-2 inhibition assays. This study found that compounds 2, 4, 5, 6, 7, 8, and 10 inhibited COX-1 dependent conversion of the exogenous arachidonic acid to PGE2 in a dose-dependent manner with IC50 values of 134.2 microM, 121.6 microM, 170 microM, 50.4 microM, 11.7 microM, 99.6 microM, and 69.6 microM, respectively. But, most of these compounds weakly inhibited COX-2 dependent PGE2 generation. Among them, only compound 4 showed relatively significant inhibitory activity (IC50: 127.6 microM).