Comparison of Inhibitory Effects of Nine Flavonoids on Prostaglandin E2 Production and COX-2 Expression in LPS-Stimulated RAW264.7 Macrophages

Prostaglandin E₂ (PGE2) has a crucial role in inflammation and is synthesized by cyclooxygenase-2 (COX-2), of which the expression is induced in inflammatory site by inflammatory stimuli like lipopolysaccharide (LPS). In the present study, nine flavonoids were tested for their effects on prostaglandin E₂ production and cyclooxygenase-2 expression in LPS-stimulated RAW 264.7 macrophages. All the nine compounds, including apigenin, lute Olin, scutellarein, quercetin, myricetin, isoquercitrin, genistein, hyperoside, rutin effectively inhibited the LPS-induced PGE2 production but only isoquercitrin showed the significant inhibitory effect on the COX-2 expression. It was found that isoquercitrin exhibited a concentration-dependent inhibition of PGE2 production and COX-2 expression with the estimated IC50 values of 25 μM and 65 μM, respectively. The results introduce isoquercitrin as a good compound capable of down regulating the expression of COX-2.