EFFECT OF SUPEROXIDE AND SUPEROXIDE-GENERATING SYSTEMS ON THE PROOXIDANT EFFECT OF IRON IN OIL EMULSION AND RAW TURKEY HOMOGENATES

Mechanisms of superoxide . O-2(-)-generating systems on the pro-oxidan t effect of iron from various sources were studied. Reaction mixtures were prepared with distilled water, oil emulsion, or meat homogenates. Free ionic iron (ferrous and ferric), ferritin and hemoglobin (Hb) we re used as iron sources, and KO2 and xanthine oxidase (XOD) systems we re used to produce . O-2(-) Thiobarbituric acid reactive substances (T BARS) values and iron contents of the reaction mixtures were determine d. Ferric iron and ferritin, in the presence or absence of superoxide- generating systems, had no catalytic effect on the oxidation of oil em ulsion but became prooxidants when reducing agent (ascorbate) was pres ent. Ferrous iron and Hb had strong catalytic effects on the oxidation of oil emulsion as shown by TEARS values. Superoxide and H2O2, genera ted from superoxide-generating systems, oxidized ferrous iron and asco rbate, and lowered the pro-oxidant effect of ferrous iron in oil emuls ion. Addition of ferric or ferrous iron increased but Hb did not have any effect on the TEARS values of raw meat homogenates. The reaction m echanisms of superoxide and the superoxide-generating systems on the p rooxidant effect of various iron sources indicated that . O-2(-) was a strong oxidizer rather than a reducing agent, and the antioxidant eff ect of XOD system in oil was caused by the oxidation of ferrous iron t o the ferric form by . O-2(-) and/or H2O2.