Preparation And Study On Functional Components From Rice Bran

Rice bran (RB) is the main by-product of rice milling industry, which has many bioactive components in it, thus study on it is very prospective. In this paper, fresh RB was used to make full use of it. Eventually, three different functional components were prepared and in-vitro activity studies were carried out to investigate their biochemical functions, which would provide theoretical information for industrial production and diversified utilization of RB.Firstly, ethanol was used for the preparation of rice bran extract I(RBE1) from RB, sediments of the process was extracted under water with amylase and protease to prepare rice bran extract II(RBE2) and III(RBE3). These three extracts were found to exhibit antioxidative,anti-hyperglycemic and anti-hypercholesterol activity respectively. The optimized parameters for RBE1 were: temperature, 55.93℃; time, 5.56 h; ratio of solution to solid, 15.59mL·g^-1, which for RBE2 and RBE3 were: Alcalase dosage 350U/g, time 5h, medium temperatureα-amylase dosage 0.2%.RBE1 exhibited great potential for DPPH·scavenging, reducing power, ferrous ion chelating, OH·scavenging and superoxide anion scavenging. Superoxide anion scavenging rate was 90.36% at the concentration of 4mg/mL.α-Glucosidase(AGC) inhibitory capacity was used to study the anti-hyperglycemic activity of RBE2. Inhibitory rate of RBE2 on AGC was 88.94% at 100mg/mL. Results of experiment on the mechanism of RBE2 on AGC showed that its inhibitory effect was reversible, Linweaver-Burk plot of kinetic studies revealed that RBE2 inhibit AGC in a mix-type manner. RBE2 inhibit ACE wit IC50 20mg/mL, which implied RBE2 could prevent or ease hypertension symptoms that often accompanied diabetes. Molecular weight of the peptides of RBE2 was determined and 72.62% of the total amount distribute between 180¹000Da.Inhibitory power on the solubility of cholesterol micelle and binding effect of bild acid were adopted respectively to examine the anti-hypercholesterol capacity of RBE3. RBE3 exhibited great inhibitory power on the solubility of cholesterol micelle, the inhibitory rate went to 56.85% at 40mg/mL. Sodium cholate, sodium deoxycholate, sodium taurocholate and sodium chenodeoxycholate were used to determine the in-vitro binding capacity of bile acid by RBE3. The binding capacities were 49.38%, 48.50%, 52.13%, 43.64% for chenodeoxycholic, deoxycholic, cholic and taurocholic, respectively, relative to cholestyramine. There was on correlation between any two bile salts, which indicates the binding mechanisms of different bile salts by RBE3 differ. X-ray diffraction and SEM results suggested that RBE3 has more complicate net-alike structure; water-holding capacity, fat-binding capacity, swelling capacity and cation exchange capacity were higher than RB; results above explained the good binding capacity of RBE3.