In Vitro Antioxidant Activity and In Vivo Anti-fatigue Effects of Oyster (Ostrea plicatula Gmelin) Peptides Prepared Using Neutral Proteinase

The amino acid profile of oyster (Ostrea plicatula Gmelin) peptides (OP) was assayed. Its in vitro antioxidant activity was determined, and its in vivo anti-fatigue activity was compared with those of oyster meat and oyster protein. Seven amino acids that may play an important role in enhancing antioxidant activity account for 25.8% of total OP content. These amino acids are histidine, proline, methionine, cysteine, tyrosine, tryptophan, and phenylalanine. The F-value of OP was 4.89, and the concentration of taurine was 45.43 mmol/mL. OP acted as a scavenger for hydroxyl radicals, 1,1-diphenyl-2-picrylhydrazyl, and superoxide anion radicals. It also inhibited lipid peroxidation. The intragastric administration of OP prolonged the swimming time to exhaustion of mice by 78% over that of the control. It decreased the levels of serum lactic acid and blood urea nitrogen by 24.8% and 11.2%, respectively. Finally, it increased the levels of liver glycogen (1.0-fold) and gastrocnemius muscle glycogen (55.6%).