ANTIOXIDANT PROPERTIES OF PHENOLIC EXTRACTS FROM DRIED JUJUBE (ZIZIPHUS JUJUBA MILL.) PEEL AGAINST OXIDATIVE DAMAGE IN ERYTHROCYTES

This study investigated the antioxidant properties of phenolic extracts of dried jujube fruit (Ziziphus jujuba Mill.). The phenolic content in jujube peel was 53 times higher than that found in the pulp. A phenolic assay revealed that p-coumaric acid, catechin, epicatechin, and rutin were the major phenolic components in jujube peel. The damage caused to rat erythrocytes induced by hydrogen peroxide (H2O2) was ameliorated by treatment with the jujube peel phenolic extracts. Compared with the control, the hemolytic level in erythrocytes treated with 10 mu M free or bound phenols from jujube peel was reduced by 42.1% or 44.0%, while the malondialdehyde level was reduced by 31.2% or 29.3%, respectively. (HO2)-O-2-induced ferryl hemoglobin formation in erythrocytes was also inhibited by free or bound phenolics extracted from jujube peel. These results demonstrated that jujube phenolic extracts could prevent hemolysis of and lipid peroxidation in the erythrocytes and could be a promising source of antioxidants.