ABSTRACT

   For the evaluation of antioxidant activities of dipeptides (carnosine, anserine), and free amino acids (histidine, 1-methylhistidine, taurine, glycine, alanine, b-alanine), four methods were used, including the analysis of the inhibition of linoleic acid autoxidation, scavenging effect on a,a-diphenyl-b-picrylhydrazyl free radical, reducing power, and chelating ability of Cu²⁺. Results showed that carnosine and anserine were antioxidants preventing lipid peroxidation in linoleic acid systems. They also possessed effective abilities as free radical scavengers, reducing agents, and copper ion chelators. The activities increased with increasing concentration. However, the constituent amino acids of dipeptides, b-alanine, histidine and 1-methylhistidine, were not as effective in inhibiting oxidation regardless of individual or combined usage. Taurine, glycine, alanine and b-alanine showed much weaker antioxidant activities than carnosine, anserine, histidine and 1-methylhistidine. No synergistic effects on antioxidation were found among compounds used in combination. The results suggested that histidine-containing compounds were related to antioxidation abilities, and the peptide linkage between b-alanine, histidine and 1-methylhistidine was involved in the antioxidant activities of carnosine and anserine.