[Peroxidation of lecithin in the presence of dihydroquercetin and its complex with ferrous iron ions].

The ability of the flavonoid dihydroquercetin to prevent or accelerate the accumulation of reactive oxygen species and the metabolites of oxidative stress, carbonyl compounds has been studied. It has been shown on a model of oxidation of lecithin that dihydroquercetin exhibits a prooxidant effect in the alkaline region of pH, whereas at neutral and acidic pH values dihydroquercetin is an effective antioxidant. In the presence of ferrous iron ions, which catalyze the Fenton's reaction, dihydroquercetin forms a complex with metal that shows the antioxidant activity in the region of high pH values. It has been found that the oxidation of lecithin in the presence of 20-200 microM ferrous iron is inhibited by dihydroquercetin to a concentration of 3.2 mM. At higher concentration of dihydroquercetin in the presence of ferrous iron, the accumulation of malonic dialdehyde occurs, indicating the presence of the prooxidant activity of dihydroquercetin.