Antioxidant effects of ovotransferrin and its hydrolysates

Food protein-derived peptides are important components for nutraceuticals, with many biological functions as well as substantial nutritional benefits. The aim of this study was to investigate the antioxidant effects of ovotransferrin (OTF) derived from egg white and its hydrolysates (OH) prepared by hydrolyzing either with acid or enzymes (protamex, alkalase, trypsin, neutrase, flavorzyme, maxazyme, collupulin., protex, promod 278, and alpha-chymotrypsin). All OH showed approximately 3.2 to 13.5 times higher superoxide anion scavenging activity than OTF, with the maximum activity found in the OH-protamex. Similar results were obtained for oxygen radical absorbance capacity assay, with the highest value in OH-alpha-chymotrypsin [1.6 mu M trolox equivalents (TE)] and the lowest value in OTF (0.2 mu M TE). However, OTF showed the most powerful 2,2-diphenyl-2-picrylhydrazyl radical scavenging activity, which reached 78.2% after 36 h of reaction. Both OTF and OH showed protective effects against the oxidative stress-induced DNA damages in human leukocytes. Overall, OTF possessed antioxidant abilities and hydrolyzation of OTF with acid or enzymes improved these abilities.