Methanol extract of Codonopsis pilosula inhibits inducible nitric oxide synthase and protein oxidation in lipopolysaccharide-stimulated raw cells

Abstract

Purpose: To evaluate the mechanism of antioxidant activity of the methanol extract of Codonopsis pilosula. Methods: Anti-oxidative properties were assessed by measuring free radical scavenging activity, nitric oxide (NO) levels, protein oxidation and reducing power, while the mechanism of antioxidative effect of Codonopsis pilosula extract was determined by measuring iNOS and COX-2 expression in lipopolysaccharide (LPS)-stimulated raw cells. Results: Codonopsis pilosula extract (CPE) exerted significant DPPH free radical and NO-scavenging activities. Protein oxidation was decreased by 30% by the CPE (1mg/ml). The extract (1mg/ml) enhanced reducing power 16-fold (compared with control). LPS-induced production of iNOS was significantly inhibited by the extract (60%), suggesting that it inhibits NO production by suppressing iNOS expression. However, LPS-induced production of COX-2 was not significantly (p < 0.05) inhibited by the extract. The levels of total phenolics, total flavonoids, and total anthocyanin in CPE were 0.38, 2.10, and 2.47 mg/g, respectively. Conclusion: These results suggest that CPE exerts marked antioxidant activity via inhibition of iNOS and protein oxidation. © Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, 300001 Nigeria. All rights reserved.