Anti-inflammatory activity of flavonoids fromPopulus davidiana

Anin vitro bioassay-guide revealed that the methanol (MeOH) extract of the stem bark ofPopulus 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-β-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. Compound7 was found to have potent inhibitory effect on COX-1 and a moderate effect on COX-2, meanwhile, compounds1–6 showed moderate inhibition against COX-1 only. Moreover, compounds5–8 exhibited suppressive effects on xanthine oxidase (XO). These results may explain, in part, the traditional uses ofP. davidiana in ethnomedicine.