In vitro antioxidant activity and in vivo anti-fatigue effect of loach (Misgurnus anguillicaudatus) peptides prepared by papain digestion

Abstract The in vitro antioxidant activity and in vivo anti-fatigue activity of loach peptide (LP) were determined. Results showed that LP contained the amino acids, which were expected to contribute to its antioxidant and anti-fatigue activities. LP could scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC 50 17.0 ± 0.54 mg/ml) and hydroxyl radicals (IC 50 2.64 ± 0.29 mg/ml). It could chelate cupric ion and inhibit the lipid peroxidation in a linoleic acid emulsion system. It also prolonged the swimming time to exhaustion of mice by 20–28% compared to the control. It increased the levels of blood glucose (28–42% increase) and liver glycogen (2.3–3.0-fold increase). It decreased the levels of lactic acid and blood urea nitrogen by 10.9–27.5% and 8.6–17.5%, respectively. It also improved the endogenous cellular antioxidant enzymes in mice by increasing the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Therefore, LP can increase an endurance capacity and facilitate recovery from fatigue.