Effects of Soybean Antioxidant Peptides (SAP) on SOD, GSH-Px, CAT Activity and MDA Level<i> </i>in Vivo<i> </i>

The superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) are important ones of antioxidant defense systems. Malonaldehyde (MDA) is formed as an end product of lipid peroxidation. Soybean peptides possess antioxidant activity. In previous study, the antioxidant activities of soybean peptides were determined in vitro . The male ICR mice were intragastrically administered by different molecular weight and dose of soybean antioxidant peptides (SAP) for 60 days. Control group was treated with saline by intragastric administration for 60 days. The SOD, GSH-Px, CAT activity and MDA level were determined in serum. The results suggested the SAP of 1-3k Da had the ability to increase significantly GSH-Px and SOD activity and decrease significantly MDA level at different dose (100 and 200 mg/kg/d) compared with control group ( P < 0.05 ). The SAP of 3-10k Da (200 mg/kg/d) enhanced the GSH-Px activity and decreased significantly MDA level compared with the control group ( P < 0.05 ). The SAP of 10-30k Da (200 mg/kg/d) had the lowest MDA level among all the groups. All the SAP groups and positive control group cannot increase the CAT activity.