EVALUATION OF ANTIOXIDANT EFFECT OF CARNO SINE ON PHOSPHOLIPIDS BY OXYGEN-UPTAKE AND TBA TEST

Carnosine (beta-Ala-His), a naturally occuring dipeptide, has been fou nd to have an antioxidant activity essentially with the thiobarbituric acid test (TBA). Here, the antioxidant activity of carnosine on iron- ascorbate catalysed phospholipid oxidation has been evaluated by oxyge n uptake and TBA test methods. Phospholipid oxidation was initiated at 25-degrees-C by an equimolar Fe3+-ascorbate mixture on total phosphol ipids (PL) extracted from turkey pectoralis muscle or on phosphatidyle thanolamine enriched (90%) fraction (PE) dispersed in PIPES buffer (10 mM, NaCl 0.15 M, pH = 6.0). It was greatly enhanced when the PE fract ion was used instead of PL. Carnosine (peptide/ phospholipid molar rat io = 1.5 to 15) decreased the oxygen consumption of PL by 5 to 25% whi le TBARS formation was inhibited by 20 to 50% (peptide/phospholipid mo lar ratio = 1.5 to 7). When evaluated on PE fraction, the antioxidant activity of carnosine, measured with the oxygen consumption method, wa s very low, but the measured TBA reactive substances decreased by 4 to 34%. The antioxidant activity of carnosine is relatively weak but it leads to an important decrease in carbonyl compounds.