Metal-Catalyzed Oxidation of Ascorbate, Deoxyribose and Linoleic Acid as Affected by Phytic Acid in a Model System

Antioxidant activity of phytate was investigated in metal-catalyzed model systems. In a dose-dependent manner, phytate facilitated oxidation of Fe (II) to Fe (III) and inhibited formation of thiobarbituric acid-reactive substances (TBARS) from Fe (II)- or hemeprotein-catalyzed deoxyribose degradation. In the presence of 100 μM Fe (III), phytate inhibited reduction of Fe (III) to Fe (II) by 100 μM ascorbic acid and it consequently inhibited ascorbate oxidation. Phytate inhibited hemeprotein- and H₂O₂-catalyzed TBARS formation from linoleic acid micelles. Inhibition by phytate of iron + ascorbate-dependent lipid peroxidation depended on the concentration of ascorbate. These results indicate that phytate may be a useful antioxidant in the protection against oxidative deterioration of foods.