Abstract:

The antioxidative effect of whey protein isolate (WPI) hydrolysates on aging rats induced by D-galactose (D-gal) was investigated. The rats were divided into seven groups including the control group, D-gal model group, D-gal-induced rats treated with unhydrolyzed WPI, D-gal-induced rats treated with WPI hydrolysates at low, middle and high dosages, and D-gal-induced rats treated with ascorbic acid as the positive group. The experiment period was last for 45 days. The effect of WPI hydrolysates on antioxidative enzyme system including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and hydrogen peroxidase (CAT) in rats was evaluated, and the content of malondialdehyde (MDA) was determined. Results showed that WPI hydrolysates at three dosage levels significantly increased SOD and GSH-Px activities and simultaneously decreased MDA content in serum, heart and kidney tissues. The CAT activity in liver tissue of treated rats was also improved (P ＜ 0.05). Moreover, a higher SOD activity was observed in rats treated with WPI hydrolysates at the dosage of 200 mg/kg· bw. Compared with the negative control, the SOD activity in serum of rats treated with WPI hydrolysates at the high dosage was increased by 29.2%. No significant difference in GSH-Px activity in kidney and CAT activity in liver between WPI hydrolysate treatment at the high dosage and the positive control of ascorbic acid was observed (P ＞0.05). In contrast, compared with the negative control, the MDA content in rats treated with WPI hydrolysates at the dosage of 100 mg/kg bw was decreased by 38.6% in heart. Therefore, WPI hydrolysates delayed the aging process of rats due to the increase of the activity in antioxdative enzyme system.

Key words: D-galactose, rats, whey protein hydrolysate, antioxidant capacity