Abstract: In this study, mixed aqueous solutions of taurine and hydrolyzed soybean protein with different mixing ratios were screened for their antioxidant activity in vitro. A rat model of exercise-induced fatigue was established and administered by gavage with the selected mixtures. To evaluate their in vivo antioxidant activity, the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) and the concentration of malondialdehyde (MDA) in the serum of rats were measured. Their anti-fatigue capacity was judged by the concentrations of serum lactic acid (LA) and blood urea nitrogen (BUN) and exercise endurance time. The results showed that the exercise endurance time of rats with exercise-induced fatigue was significantly shortened compared with normal rats (P < 0.05). The activities of SOD, GSH-Px and CAT were increased and MDA concentration was decreased after administration with the taurine-hydrolyzed soybean protein mixtures. The 1:10 (m/m) mixture had the most significant antioxidant effect in vivo. Correspondingly, it was the most effective in prolonging the exercise endurance time and reducing the concentrations of serum LA and BUN, indicating the best anti-fatigue effect. SOD activity was plotted against exercise endurance time, revealing a positive correlation between the antioxidant capacity of the taurine-hydrolyzed soybean protein mixture and its anti-fatigue effect (R2 = 0.820 5). This research can provide a reference for the development of compound functional anti fatigue products based on hydrolyzed protein and taurine.

Key words: taurine; hydrolyzed soybean protein; antioxidant activity; exercise-induced fatigue