Phytic acid inhibits free radical formation in vitro but does not affect liver oxidant or antioxidant status in growing rats.

The objective of this study was to determine the effects of phytic acid on free radical generation in vitro and in growing rats. Electron spin resonance spectroscopy studies using 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap indicate a complete inhibition of hydroxyl radical formation via the iron-catalyzed Fenton reaction at molar phytic acid/iron ratios >5. However, phytic acid had no scavenging effect on superoxide radicals generated in the xanthine/xanthine oxidase reaction. For the in vivo study, male growing albino rats were fed purified diets based on casein, cornstarch and vitamin E-stripped corn oil differing in the concentration of iron (30 or 300 mg/kg), phytic acid (0 or 10 g/kg) and dl-alpha-tocopheryl acetate (0 or 50 mg/kg). At marginal dietary iron supply, phytic acid supplementation reduced apparent Fe absorption, thereby decreasing liver Fe concentration. Dietary iron and phytate had no effect on the level of hepatic alpha-tocopherol, reduced glutathione, thiobarbituric acid-reactive substances and protein carbonyls. The concentration of thiobarbituric acid-reactive substances and protein carbonyls in the liver decreased as dietary vitamin E was increased from 0 to 50 mg/kg diet. The results obtained provide evidence for antioxidant properties of phytic acid under in vitro conditions. However, neither phytic acid nor iron had any significant effect on liver oxidant or antioxidant status in vivo in growing rats.