Evaluation of Antioxidant and Inhibitory Activities for Different Subclasses Flavonoids on Enzymes for Rheumatoid Arthritis

Antioxidant activities of flavonoids were decreased in the order of flavonols > flavanones > flavones. Inhibitory intensities for hyaluronidase and collagenase reaction differed clearly according to flavonoid subclasses. Kaempferol, quercetin, myricetin, and rutin in flavonols inhibited hyaluronidase reaction specifically, while apigenin, luteolin, baicalin, and baicalein in flavones showed specific inhibition to collagenase reaction. In addition, the flavonoids, except baicalin and catechin, inhibited potently LPS-induced nitrite production in a dose-dependent manner, which might be mainly due to the suppression of inducible nitric oxide (NO) synthase. Quercetin and luteolin showed the strongest inhibitory activities on 15-lipoxygenase (LOX), and quercetin showed relatively potent inhibition on cyclooxygenase-1 (COX-1) reaction. Otherwise, all tested flavonoids possessed the inhibitory activity to COX-2 reaction, and especially luteolin, kaempferol, hesperetin, and naringin showed relatively the potent inhibition on COX-2 reaction. This report elucidated the anti-inflammatory activities, such as the antioxidant property, inhibition of NO production, and inhibition of inflammatory enzymes (hyaluronidase, collagenase, LOX, and COXs) of several subclass flavonoids.