Antioxidant activity of gelatin hydrolysates derived from salmon (Oncorhynchus keta) skin and their cytoprotective effect on oxidative injury of rat hepatocytes

Seven chum salmon skin gelatin hydrolysates with degree of hydrolysis (DH) 4. 7%～13. 5% were prepared by three commercial proteases, Alcalase, papain or Neutrase, respectively. The antioxidant activity of gelatin hydrolysates was evaluated by the ability of scavenging free radicals. The results demonstrated that the antioxidant activity of the gelatin hydrolysates was gradually increased with the increase of degree of hydrolysis in a dose-dependent manner. Rat hepatocyte BRL cells were preincubated with gelatin hydrolysates (0.5, 1, 2mg/mL) and then were oxidative injuried by H2O2 (5mmol/L) . The cell viability, leakage of lactate dehydrogenase (LDH) , content of malondialdehyde (MDA) and GSH were determined by commercial kits. The results indicated that the cell viability was remarkably improved while the leakage of LDH and MDA formation were reduced significantly with the content of GSH almost unchanged. The statistical analysis of the results showed that seven gelatin hydrolysates played a protective role in H2O2-induced oxidative injury, and the cell viability was positively correlated with antioxidant activity of gelatin hydrolysates, while leakage of LDH and the content of MDA formed were negatively correlated with antioxidant activity of gelatin hydrolysates.