Preparation Of Polysaccharides From Crassostrea Gigas And It’s Biological Activities

Crassostrea gigas is one of the traditional aquacultured shellfish in China, which has rich nutrition and special health value. In this study, extraction technology, physical and chemical properties, structure and biological activity in vitro and in vivo studies of polysaccharide were studied.Therefore,The results will be helpful for the application of C. gigas.A water-soluble polysaccharide was isolated from C. gigas(CGPS-1) by hot-water extraction, isoelectric precipitation, hydrolysis and ultrafiltration without using ethanol. Based on the calibration with Dextran, CGPS-1 had a molecular weight of approximately 6.5 × 106 Da. CGPS-1 was analyzed using high-performance liquid chromatography(HPLC), Fourier-transform infrared spectroscopy and 1H and 13 C nuclear magnetic resonance spectroscopy. Based on the data, CGPS-1 was found to be a uniform glucose polymer with α-pyranoside based linkage.CGPS-1 is separated using hydrophobic chromatography on an ME-1 resin column. Three major polysaccharide fractions, CGPS-2, CGPS-3 and CGPS-4, were analyzed by Fourier-transform infrared and 13 C nuclear magnetic resonance spectroscopy. These three fractions showed free radical scavenging activity against ABTS+· in vitro.The free protein and other impurities in CGPS-1 were wiped out by pepsin- trypsin-Sevag method. After the process of dialyzing, the obtained polysaccharides were further purified by DEAE-52 column chromatography and Sephadex G-100 chromatography, CGPS-A was obtained. Molecular and structural of CGPS-A were preliminarily analyzed.The results of antioxidation test in vitro showed that CGPS-1 played a good role in the antioxidation process. CGPS-1 was obviously able to scavenge DPPH free radical in the concentration of 5.0 mg/m L and the scavenging rate was 90%; while in the concentration of 10 mg/m L inhibition rate of hydroxyl radical was 84%. The protective effect of CGPS-1 on acute carbon tetrachloride and chronic ethanol-induced liver injury was investigated in mice. Treatment with CGPS-1 decreased serum aspartate aminotransferase(AST), serum alanine aminotransferase(ALT), and malondialdehyde aldehyde(MDA) levels; increased superoxide dismutase(SOD) activity; and improved hepatic injury in both the acute and chronic models of liver injury in mice. These results suggest that CGPS-1 possesses potent hepatoprotective activity.CGPS-1 has a strong inhibitory activity on angiotensin-converting enzyme(ACE).