The Preparation Of Soy Peptides And Study On Its Antioxidant Effect In Vitro And In Vivo

Fundamental study in free radical showed that oxygen radicals relate to hundreds of diseases. Previous data showed that many chronic diseases and senile phenomenon of human being were all relevant to radical level unbalance in the body. Excessive radicals cause oxidation damage in the body. If the damage could not be repaired timely and be collected to some degree, it would result in some diseases. Bio-antioxidant can help people hold radical balance in the body. It is possible to develop potent antioxidant drugs and functional foods through studying and modifying some natural foods having antioxidative activity.Soy peptides were short peptide mixture obtained by soybean protein enzymatic hydrolysis. By far, soy peptides were found to have bioactivity such as antioxidant ability, blood pressure reducing activity, cholesterol and blood sugar reducing activity, anti-fatigue activity and others. Antioxidant ability of soybean peptide is the basis of other physiological functions. It is possible to develop new drug or food products to cure the disease triggered by free radicals by screen and separate antioxidant soybean peptide.Based on the results of one-factor-at-a-time-technique,a three-level Box-Behnken factorial design combining with response surface analysis (RSA) was employed to optimize the enzymatic hydrolyze condition of antioxidant soy peptides. It shows that the optimum conditions for preparing high antioxidant soy peptides by alkaline protease were: substrate concentration 8.50%, proteases concentration 8 750 U per gram substrate, pH11, temperature 55℃, and time 3.0 h. The soy peptides produced in this condition had strong scavenging activities of hydroxyl radicals; scavenging rate on them was 65.37%.The defatted soy meal hydrolysate was separated into three parts using Sephadex G-25 gel filtration chromatography; the second part FⅡhas strong antioxidative activities. So we prepare FⅡand test its antioxidant bioactivity in vitro and in vivo. The experiment in vitro shows that soy peptides have significant effect on scavenging hydroxyl radicals and superoxide anion free radicals. It could inhibit the generation of MDA in liver homogenate, hemolysis of red blood cell induced by hydrogen peroxide. All the results above show that soy peptides have antioxidation effect in vitro.POV were measured by Oven Storage Method to research on the activities of oxidation resistance of the soy peptides by soybean oil and colza oil as substrates. The result shows that the soy peptides have antioxidative activities to resist lipin-oxidation.The senior modle was built up with Kunming-mice by treating D-galactose. Different doses of soy peptides were administered to the experimental mice. Brain index, heart index, liver index, spleen index, kidney index were measured. MDA content and SOD activity of mice in serum were measured. The content of MDA, activity of SOD, GSH-Px and CAT of mice in brain and liver were measured. The results indicated that soy peptides could (1) effect on spleen index of mice;(2) increase the activities of SOD, reduce the level of MDA in serum;(3) reduce the level of MDA in liver and brain;(4)increase the activities of SOD, GSH-Px and CAT in liver and brain.