An in vitro bioassay-guide revealed that the methanol (MeOH) extract of the stem bark of Populus davidiana showed considerable inhibitory activity against cyclooxygenase (COX-1, COX-2). Continuous phytochemical study of the MeOH extract of this plant led to the isolation of ten flavonoids; sakuranetin (1), rhamnocitrin (2), 7-O-methylaromadendrin (3), naringenin (4), eriodictyol (5), aromadendrin (6), kaempferol (7), neosakuranin (8), sakuranin (9) and sakurenetin-5,4'-di-beta-D-glucopyranoside (10). Their structures were identified on the basis of their physicochemical and spectroscopic analyses. The isolated compounds, 1-10, were tested for their inhibitory activities against COX-1 and COX-2. Compound 7 was found to have potent inhibitory effect on COX-1 and a moderate effect on COX-2, meanwhile, compounds 1-6 showed moderate inhibition against COX-1 only. Moreover, compounds 5-8 exhibited suppressive effects on xanthine oxidase (XO). These results may explain, in part, the traditional uses of P. davidiana in ethnomedicine.

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).

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Cytotoxic bioassay-guided fractionation of methanol extract of Angelicae Sinensis Radix led to the isolation of a new dimeric Z-ligustilide, named neodiligustilide (1), together with three known compounds, Z-ligustilide (2), 11(S),16(R)-dihydroxy-octadeca-9Z, 17-dien-12,14-diyn-1-yl acetate (3), and 3(R),8(S)-falcarindiol (4). Among them, 2 showed the strongest cytotoxicity against L1210 and K562 cell lines with IC50 values of 2.27 +/- 0.10 and 4.78 +/- 0.18 microM, respectively, while 1 showed moderate cytotoxicity with IC50 values of 5.45 +/- 0.19 and 9.87 +/- 0.14 microM. Two polyacetylenes, 3 and 4, showed cytotoxicity only against L1210 cell line with IC50 values of 2.60 +/- 0.90 and 2.87 +/- 0.49 microM, respectively.

The hexane extract of the fruit of Schizandra chinensis (Schisandraceae) was found to show significant inhibition of the activity of acetylcholinesterase enzyme (AChE). In further studies, fourteen lignans were isolated, and evaluated for their inhibitory effect on AChE. The compounds having both aromatic methylenedioxy and hydroxyl groups on their cyclooctadiene ring, such as gomisin C (6), gomisin G (7), gomisin D (8), schisandrol B (11) and gomisin A (13), entirely inhibited AChE in dose dependent manners, with IC50 values of 6.71 +/- 0.53, 6.55 +/- 0.31, 7.84 +/- 0.62, 12.57 +/- 1.07 and 13.28 +/- 1.68 microM, respectively. These results indicate that the lignans could potentially be a potent class of AChE inhibitors.