Antioxidant activity of pomegranate peel extracts

Water,methanol,acetone and ethyl acetate were used to extract polyphenols from pomegranate peels.The antioxidant activity of the dried extracts was characterized by peroxide value(POV) assay in lard and 1,1-diphenyl-2-picryl hydrazyl(DPPH) radical method.All the extracts could inhibit lard peroxidation and scavenge DPPH free radical.Their antioxidant activity was increased with their concentrations.In lard system,acetone extract showed the highest inhibitory activity on lipid peroxidation,followed by water,methanol and ethyl acetate extracts.When acetone extract was at 0.1%(g/g lard),its antiliperoxidation was close to that of 0.02% pure green tea polyphenols or 0.02% BHT. In DPPH system,the extracts had the following order of DPPH radical scavenging activity: water extractacetone extractmethanol extractethyl acetate extract.The water extract exhibited 85.2% radical-scavenging rate at 0.0175 mg/mL,which was lower than that of pure green tea polyphenols but much higher than that of BHT.