Anti-oxidative actions of Curcuma zedoaria extract with inhibition of inducible nitric oxide synthase (iNOS) induction and lipid peroxidation

Abstract

The aim of this study was to determine if Curcuma zedoaria extract has antioxidant activities. Anti-oxidative actions were explored by measuring free radical scavenging activity, nitric oxide (NO) levels, and reducing power. The mechanism of anti-oxidative action of C. zedoaria was determined by measuring inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression in lipopolysaccharide (LPS) stimulated RAW 264.7 cells. 70% methanolic extract of C. zedoaria exerted significant diphenylpicrylhydrazyl (DPPH) free radical and NO scavenging activities in a dose-dependent manner. More strikingly, the C. zedoaria extract exerted dramatic reducing power activity (30-fold over control). Production of iNOS induced by LPS was significantly inhibited by the C. zedoariaextract, suggesting that it inhibited NO production by suppressing iNOS expression. These results obtained suggest that 70% methanolic extract of C. zedoaria has a significant anti-oxidant activity via inhibiting iNOS induction. The extract contains anti-oxidant components including phenolics, flavonoids and anthocyanin at the concentration of 1.062, 16.33, and 30.57 mg/g, respectively, suggesting that these components may play a significant role in displaying its anti-oxidative action. Key words: Curcuma zedoaria, free radical, lipid peroxidation, iNOS, NO, COX-2.