LIPID-PEROXIDATION OF MUSCLE FOOD - THE ROLE OF THE CYTOSOLIC FRACTION

The cytosolic extract from turkey muscle tissues contained compounds that partially inhibited membrane lipid peroxidation initiated by an iron-redox cycle (ascorbic acid-ferric ions and iron-NADPH enzymatic reaction). The cytosolic extract, however, totally inhibited lipid peroxidation catalyzed by H2O2-activated metmyoglobin. The cytosolic extract was separated into low and high molecular weight fractions, and both fractions exhibited inhibitory effects on H2O2-activated myoglobin. Membrane lipid peroxidation initiated by the iron-redox cycle was inhibited partially by the high molecular weight fraction but accelerated by the low molecular weight fraction. Turkey muscle cytosol contains reducing compounds at a level equivalent to approximately 3 mg of ascorbic acid/100 g of fresh weight or at a concentration of approximately 150 mu-M. These reducing compounds, 80% of which contain ascorbic acid, seem to be responsible for the activation of the iron-redox cycle and for the inhibition of H2O2-activated myoglobin toward membranal lipid peroxidation.