Effect of the antioxidant (+)-cyanidanol-3 on H2O2 formation and lipid peroxidation in liver microsomes

(+)-Cyanidanol-3, a flavonoid with antioxidant properties, leads to an increase of hydrogen peroxide production when added to liver microsomes from untreated and variously pretreated rats. No distinct extra production of hydrogen peroxide was observed in liver microsomes from guinea pig, rabbit and man. The optimal stimulatory concentration was 100 microM; at higher concentrations a lesser degree of stimulation was obtained. Metyrapone inhibited the stimulation process, indicating that cytochrome P-450 function may be involved. Increase of hydrogen peroxide formation occurred at the same (+)-cyanidanol-3 concentrations that were capable to inhibit lipid peroxidation, suggesting that the interference of (+)-cyanidanol-3 with the oxidase function of cytochrome P-450 does not compromise its antioxidative activity towards lipid peroxidation.