In vitro antioxidant activity of Piper nigrum Linn.

Abstract

The fractions R1, R2 and R3 obtained from pet ether extract of Piper nigrum Linn. (PEPN) were investigated for in vitro antioxidant activity.1,1-Diphenyl-2-picryl-hydrazyl (DPPH) radical, superoxide anion radical, nitric oxide radical, and hydroxyl radical scavenging assays were performed. The free radical scavenging activity of the different fractions PEPN increased in a concentration dependent manner. R3 and R2 fraction of PEPN in 500µg/ml inhibited the peroxidation of a linoleic acid emulsion by 60.48±3.33% and 58.89±2.51%, respectively. In DPPH free radical scavenging assay, the activity of R3 and R2 was found almost similar. R3 (100µg/ml) fraction of PEPN inhibited 55.68±4.48% nitric oxide radicals generated from sodium nitroprusside whereas curcumin in the same amount inhibited 84.27±4.12%. Moreover, PEPN scavenged the superoxide radical generated by the Xanthine/Xanthine oxidase system. The fraction R2 and R3 in the dose of 1000µg/ml also inhibited 61.04±5.11% and 63.56±4.17% respectively, the hydroxyl radical generated by Fenton's reaction. The amounts of total phenolic compounds were also determined and 56.98µg pyrocatechol phenol equivalents were detected in one mg of R3.

Keywords: Lipid peroxidation; phenolic compounds; Piper nigrum