Isolation and identification of antioxidative peptides from porcine collagen hydrolysate by consecutive chromatography and electrospray ionization–mass spectrometry

The porcine skin collagen was hydrolyzed by different protease treatments to obtain antioxidative peptides. The hydrolysate of collagen by cocktail mixture of protease bovine pancreas, protease Streptomyces and protease Bacillus spp. exhibited the highest antioxidant activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, metal chelating and in a linoleic acid peroxidation system induced by Fe2+. And degree of hydrolysis highly affected the antioxidant properties of the hydrolysates. Four different peptides showing strong antioxidant activity were isolated from the hydrolysate using consecutive chromatographic methods including gel filtration chromatography, ion-exchange chromatography and high-performance liquid chromatography. The molecular masses and amino acid sequences of the purified antioxidant peptides were determined using electrospray ionization (ESI) mass spectrometry. One of the antioxidative peptides, Gln-Gly-Ala-Arg, was then synthesized and the antioxidant activities measured using the aforementioned methods. The results confirmed the antioxidant activity of this peptide, and adds further support to its feasibility as a provider of natural antioxidants from porcine skin collagen protein.