NATURAL ANTIOXIDANTS PRODUCED IN OXIDIZED LIPID AMINO-ACID BROWNING REACTIONS

1-Substituted pyrroles (1 and 2) and 1-substituted 2-(1'-hydroxypropyl )pyrroles (3-5) were produced in reactions between a lipid peroxidatio n product, 4,5(E)-epoxy-2(E)-heptenal, and the amino acid lysine. The antioxidative activity of compounds 1-5 was studied. Oxidative stabili ty was evaluated in refined soybean oil containing compounds 1-5, buty lated hydroxytoluene (BHT), n-propyl gallate or L-lysine, at concentra tions of 50-200 ppm. Oils were either oxidized at 60 degrees C and oxi dation products determined by the thiobarbituric acid-reactive substan ces assay, or they were oxidized at 110 degrees C by the Rancimat meth od. Although both methods gave similar results, greater differences we re observed at 60 degrees C than 110 degrees C. Addition of compounds 1-5, L-lysine, BHT, and propyl gallate sig significantly (P < 0.01) pr otected the oil against oxidation. The effectiveness order found was: L-lysine << compounds 3-4 compounds 1-2 < compound 5 approximate to BH T << propyl gallate.