| The aim of the study was to explore the effects of hydrolysates of soybean protein and casein on antioxidation in vitro and on antioxidative function in liver and plasma of mice and CC14-induced rats in vivo. This study consists of three parts as follows.1. Effects of hydrolysates of soybean protein and casein on antioxidation in vitroThe hydrolyzation condition of soybean protein and casein by papain, subtilisin, pepsin with the criterion of scavenging activity of hydroxyl radical of hydrolysed soybean protein and casein was studied by single factor and orthogonal experiment design. The optimum condition of soybean protein concentrate has been found as follows: papain, pH7.5, enzyme concentration 6%, hydrolysis temperature 40 C, hydrolysis time 30min and the scavenging rate of hydroxyl radical is 68.20%. The optimum condition of soybean meal has been found as follows: papain, pH7.5, enzyme concentration 6%, temperature 40掳C, time 30min and the scavenging rate of hydroxyl radical is 58.67%. The optimum condition of casein has been found as follows: papain, pH7.5, enzyme concentration 8%, temperature 45 C, time 90min and the scavenging rate of hydroxyl radical is 72.06%.2. Effects of hydrolysates of soybean protein and casein on antioxidation of mice80 mice were randomly divided into 8 groups: Control group, Vitamin E group(VE), low dose of soybean protein hydrolysate group (SPH1), middle dose of soybean protein hydrolysate group (SPH2) and high dose of soybean protein hydrolysate group (SPH3) , low dose of casein hydrolysate group (CHI), middle dose of casein hydrolysate group (CH2) and high dose of casein hydrolysate group (CH3) . The mice were administrated with 0.25mL normal saline, 7.2mg/mLVE, 4mg/mL, 12mg/mL and 20mg/mL soybean protein hydrolysates, 4mg/mL, 12mg/mL and 20mg/mL casein hydrolysates respectively one time a day. The mice were euthanatized after ten days being treated. The activities of SOD, GSH-Px and the level of MDA in liver and plasma were determined. Vitamin E significantly reduced MDA level in plasma and liver of mice (P<0.05) , but did not affect activities of SOD and GSH-Px in plasma and liver. Different doses of soybean proteinhydrolysates could improve antioxidant capacities in mice, especially the high dose one (SPH3) which envidently increased the activities of SOD and GSH-Px in liver and activity of GSH-Px in plasma(.P<0.01), but did not affect MDA level in plasma and liver of mice. Different doses of casein hydrolysates could improve antioxidant capacities in mice, especially the high dose one (CH3) which significantly increased activities of GSH-Px in liver and activities of SOD and GSH-Px in plasma, and reduced the level of MDA in plasma and liver of mice (P<0.05) .3. Effects of hydrolysates of soybean protein and casein on antioxidation of CC14-induced ratsThe protective effect of Vitamin E (VE), soy protein, soy protein hydrolysate, casein and casein hydrolysate on CC14-induced oxidative stress was investigated in rats. 70 SD rats were randomly divided into 7 groups: Control, CC14, CC14+VE, CC14+CAS (casein), CC14+SP (soybean protein), CC14+CH and CC14+SPH. Rats were orally administered with 1mL normal saline, normal saline, VE (8mg/mL), CAS, SP, CH and SPH (50mg/mL) respectively for four weeks. After two weeks, all the rats were supplemented with 30%CC14 (l.5mL/kg) except rats in control group twice per week for two weeks successively. The rats were euthanatized after four weeks. The activities of CAT, SOD, GSH-Px, GOT, GPT and MDA in plasma and the activities of CAT, SOD, GSH-PX and MDA in liver were determined. The results showed as follows: the activities of CAT, SOD and GSH-Px in liver and plasma of rats did not change greatly(P>0.05)while the level of MDA significantly increased (P<0.01) after being treated with CC14. Hydrolysates of soybean protein and casein significantly increased the activities of SOD, GSH-Px in plasma and CAT, SOD, GSH-Px in liver (P<0.05) and reduced the level of MDA in plasma and liver. VE and hydrolysates of soybean...
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