In vitro antioxidant activity of pet ether extract of black pepper

OBJECTIVE To investigate the in vitro antioxidant activity of different fractions (R1, R2 and R3) obtained from pet ether extract of black pepper fruits (Piper nigrum Linn.) MATERIALS AND METHODS The fractions R1, R2 and R3 were eluted from pet ether and ethyl acetate in the ratio of 6:4, 5:5 and 4:6, respectively. 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) radical, superoxide anion radical, nitric oxide radical, and hydroxyl radical scavenging assays were carried out to evaluate the antioxidant potential of the extract. RESULTS The free radical scavenging activity of the different fractions of pet ether extract of P. nigrum (PEPN) increased in a concentration dependent manner. The R3 and R2 fraction of PEPN in 500 microg/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 were found to be almost similar. The R3 (100microg/ml) fraction of PEPN inhibited 55.68+/-4.48% nitric oxide radicals generated from sodium nitroprusside, whereas curcumin in the same concentration 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 doses of 1000microg/ml inhibited 61.04+/-5.11% and 63.56+/-4.17%, respectively. The hydroxyl radical was generated by Fenton's reaction. The amounts of total phenolic compounds were determined and 56.98 microg pyrocatechol phenol equivalents were detected in one mg of R3. CONCLUSIONS P. nigrum could be considered as a potential source of natural antioxidant.