Antioxidative properties of peptides obtained from porcine myofibrillar proteins by a protease treatment in an Fe (II)-induced aqueous lipid peroxidation system.

The porcine myofibrillar protein hydrolysate obtained by a papain treatment showed antioxidative activity in a system of linolenic acid peroxidation induced by Fe(2+). The five peptides, DSGVT, IEAEGE, DAQEKLE, EELDNALN, and VPSIDDQEELM, have been characterized as antioxidative peptides (Saiga et al., J. Agric. Food Chem., 51, 3661-3667 (2003)). These peptides were synthesized and their antioxidative activity evaluated. The antioxidative activity of four peptides, excluding DSGVT, was confirmed by their addition at 0.1% to the peroxidation system. To clarify the mechanism for the antioxidative activity of these peptides, their short peptides with amino acid deletions at the C- or N-termini were synthesized. The antioxidative activity gradually decreased with decreasing peptide length. Replacing the charged amino acids in these peptide sequences with Ala also affected their antioxidative activity. We hypothesize that the anions from acidic amino acids and the cations from iron interacted with each other and inactivated the pro-oxidant, Fe (II).