In vitro anti-inflammatory effects of quercetin 3-O-methyl ether and other constituents from Rhamnus species.

The anti-inflammatory activities of the isolated flavonoids, quercetin 3-O-methyl ether (1), kaempferol (2), and quercetin (3), of Rhamnus nakaharai, and anthraquinone, frangulin B (4), of Rhamnus formosana, were assessed in vitro by determining their inhibitory effects on the chemical mediators released from mast cells, neutrophils, macrophages, and microglial cells. Compounds 1 - 3 strongly inhibited the release of beta-glucuronidase and lysozyme from rat neutrophils stimulated with formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB). Compound 1 strongly inhibited superoxide anion formation in fMLP/CB or phorbol 12-myristate 13-acetate (PMA)-stimulated rat neutrophils. Compound 1 exhibited potent inhibitory effect on tumor-necrosis factor-alpha ( TNF-alpha) formation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells while 1 and 4 showed potent inhibitory effects on TNF-alpha formation in LPS/IFN-gamma (interferon-gamma)-stimulated murine microglial cell lines N9.