Study On The Immunomodulating Polysaccharides From Rice Bran

Rice Bran is an abundant, cheap, and safe raw material for the extraction of immunomodulating polysaccharides. The extraction, purification and immunomodulating activities of rice bran polysaccharides were studied in this paper. The immunomodulating activities of each fraction were measured in vivo and in vitro, and an active fraction, RBP-II, was purified. Its molecular composition and structure were characterized. Meanwhile, the immunomodulating mechanism of RBP-II was also investigated.The suitable extraction techniques for water-soluble rice bran polysaccharide (high temperature, HWSRBP; low temperature, LWSRBP) and alkaline-solubb polysaccharide (ASRBP) from extrusion defatted rice bran were established, and the corresponding extraction parameters were also optimized. Rise in extraction temperature was found to greatly increase the crude polysaccharide yield. Under optimum conditions, the yield of HWSRBP was 2.82%, higher than by reported techniques. The yield of ASRBP was 2.32%. The composition of each non-starch polysaccharide fraction was analyzed for the first time. For primary purification, various procedures were used to remove impurities existing therein, such as starch, protein, etc. 10% Ca(OH)2was added to the solution containing the polysaccharide HWSRBP to precipitate phytin ,50 that the ash content of HWSRBP was decreased from 14% to 1.3%.Compared with other type of crude rice bran polysaccharide, HWSRBP has significantly immunomodulating activity .When HWSRBP was orally administered to mice, the spleen and thymus index of mice were greatly increased ; the lymphocyte proliferation degree was increased three times and the phagocyte ratio and phagocyte index were also significantly higher than control group in a dose-dependent manner. ASRBP has immunomodulating activity when orally administered at high and middle dose, while LWSRBP has lower immunomodulating than HWSRBP and ASRBP. AISRBP didn't had no immunomogolating activity. HWSRBP was studied in depth in the following research for its great biological activities and highest yield.The immunomodulating activity of HWSRBP in vitro was studied. HWSRBP can significantly enhance the proliferation of T lymphocyte induced with Con A in vitro, and is dose dependent. This method was used to detect the biological activity of each purified fraction. HWSRBP can also enhance nitric oxide secretion of peritoneal macrophage of mice, but this effect had no statistical significance. HWSRBP has marked anti-complementary activity, and this method was suitable to detect biological activities of polysaccharides in short periods in view of agent variations.HWSRBP was successively fractionated by stepwise ethanol precipitation, and column chromatography on Sepharose CL-6B and DEAE Sepharose Fast Flow. The effect of each fraction at various concentrations was measured on the proliferation of T lymphocytes induced by Con A in vitro, and an active fraction, RBP-II, was purified. The relationship between the structure and the biological activity of RBP-II was studied. Results indicated that anti-complementary activity of RBP-II was due to polysaccharide rather than LPS and thepulyplionol moieties, feruiic acid, being an possible component in rice bran.The physicochemical properties of RBP-II were studied. Gas Chromatography (GC) shows that RBP-II consist Arabinose, Xylose, Glucose and Galactose in a ratio of 1.37: 0.50: 0.20: 1; Its molecular weight is about 191 000. UV, IR and NMR spectra reveal that RBP-II consist a repeating unit with the following structure:RBP-II is a new polysaccharide isolated and purified from defatted rice bran.RBP and RBP-II can stimulate humoral, cellular and non-specific immunity by oral administration in mice with immunosuppressive agent Cyclophophamide (CY). J.tp. injection of CY can inhibit the proliferation of splenocytes , phagocytic function of PM . While RBP-II can promote non-specific immunity such as the phagocytosis of macrophages, stimulate cellular immunity such as the proliferation of splennocytes and the genesis...