METAL-CATALYZED OXIDATION OF ASCORBATE, DEOXYRIBOSE AND LINOLEIC-ACIDAS AFFECTED BY PHYTIC ACID IN A MODEL SYSTEM

Antioxidant activity of phytate was investigated in metal-catalyzed mo del 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 de oxyribose degradation. In the presence of 100 mu M Fe (III), phytate i nhibited reduction of Fe (III) to Fe (II) by 100 mu M ascorbic acid an d it consequently inhibited ascorbate oxidation. Phytate inhibited hem eprotein- and H2O2-catalyzed TBARS formation from linoleic acid micell es. Inhibition dy phytate of iron + ascorbate-dependent lipid peroxida tion depended on the concentration of ascorbate. These results indicat e that phytate may be a useful antioxidant in the protection against o xidative deterioration of foods.