Abstract: The antioxidant activities of reduced glutathione, L-carnosine, N-acetyl-L-carnosine, Gly-L-Tyr, L-Ala-Gln and Gly-Gly were measured by various chemical assays, including DPPH radical scavenging assay, ABTS radical scavenging assay, ferrous ion chelating assay and ferric thiocyanate method (for determining the inhibitory activity against linoleic acid peroxidation). The results showed that all these peptides had antioxidant activity, especially in linoleic acid system for peroxidation inhibitory activity. The antioxidant activity of reduced glutathione and Gly-L-Tyr were similar to those of BHA and VE and better than those of L-carnosine, L-Ala-Gln and Gly-Gly, and N-acetyl-L-carnosine had the weakest antioxidant activity. L-Carnosine, which contains histidine, was excellent in chelating ferrous ions, and the ability reached 92.51% at the concentration of 1 mg/mL, which was similar to that of EDTA.

Key words: reduced glutathione, dipeptide, antioxidant activity, metal ion chelating