LIPOPEROXIDATION INDUCED BY HYDROGEN-PEROXIDE IN HUMAN ERYTHROCYTE-MEMBRANES .2. COMPARISON OF THE ANTIOXIDANT EFFECT OF GINKGO-BILOBA EXTRACT (EGB-761) WITH THOSE OF WATER-SOLUBLE AND LIPID-SOLUBLE ANTIOXIDANTS

An in vitro model using healthy human erythrocyte suspensions was used to compare the antioxidant effect of standardized Ginkgo biloba extra ct (EGb 761) with those of water-soluble (ascorbic acid, glutathione a nd uric acid) and lipid-soluble (a-tocopherol and retinol acetate) ant ioxidants. Lipid peroxidation was induced by hydrogen peroxide in the absence (control) and presence of antioxidants at low (25 mu g/ml) and high (250 mu g/ml) concentrations. Malondialdehyde production was det ermined as the indicator of lipid peroxidation during the incubation p eriod. The results suggest that all of the antioxidants, except ascorb ic acid, have antioxidant potential in this system in a concentration- dependent manner. When the antioxidants were compared, EGb 761 was fou nd to be more effective than water-soluble antioxidants, and as effect ive as lipid-soluble antioxidants. Among the lipid-soluble antioxidant s there was no significant difference in potency between alpha-tocophe rol and retinol acetate, but uric acid was the most potent of the wate r-soluble antioxidants. The antioxidant potency of EGb 761 appears to be comparable with that of the well-known antioxidants alpha-tocophero l and retinol acetate.