Nutrients, Extraction, Isolation, Purification, Antioxidant Activity And Structural Elucidation Of Polysaccharides From The Durvillaea Antarctica

There are three parts in this research:(1)Determination the nutrients of Durvillaea antarctica; (2)compare three polysaccharide extraction methods include water extraction, ultrasonic wave and microwave extraction, use response surface analysis to optimize the best extraction process. Adopt the method of the optimized extraction of polysaccharide, analysis the antioxidant activity of polysaccharide; (3) purification, physical-chemical character research and sugar structure elucidation.Durvillaea antarctica is rich in minerals、 protein and crude fiber, and low fat content, the ash content is 10.15%, the protein content is 10.699%, the crude fat is only 0.874%, the crude fiber content is 5.8%. Heavy metal content were not overweight, is the ideal food in our life.Polysaccharide yield of water extraction, ultrasonic wave and microwave extraction respectively was 1.57%,2.90%,3.85%. The response surface analysis was used to determine the optimum conditions of polysaccharide extraction, the optimal extractive techniques of microwave extraction were as follows:the ratio of water to material 33, extraction temperature 86℃, extraction time 31 min, repeatedly extracting 3 times, and the extracting yield reached 5.347% under the conditions.Durvillaea antarctica polysaccharide(HRC) were extracted under the conditions, precipitated into different crude polysaccharide HRC30, HRC60 and HRC80 by different degree of ethanol, yield respectively was 12.26%、4.22%、4.88%, the total sugar content respectively was 32.94%、 31.56%、35.19%. Analysis the antioxidant activity of HRC80, HRC60 and HRC30, the result showed that size of oxidation resistance ability was HRC80>HRC60>HRC30. HRC80 was purified using DEAE Sepharose Fast Flow and Sephacryl S gel-filtration chromatography repeatedly, obtained homogeneous polysaccharides HRCS. IR spectra showed that the sugar characteristic peaks were existed. UV scanning indicated that it contained no nucleic acid and protein. HPLC producing a single symmetrical peak, indicated that it was homogeneous and the molecular weight was 1.79×105Da. Molecular weight had the certain influence for the activity of polysaccharide, too big or too small were detrimental to the activity of polysaccharide, ordinary the molecular weight of seaweed polysaccharides was significant activity in 1 × 105 Da～5 × 105 Da, therefore, HRCS had obvious biological activities.HRCS was investigated by GC analysis, GC-MS analysis and NMR spectroscopic methods to confirm the sugar composition, the number of sugar residues and the form of glycosyl linkage. HRCS composed of L-rhamnose, D-glucose and D- galactose, the molar ratio is 1.70:1:0.16. And the methylation showed that the glucose residues were mainly 1,3-linked and 1,6-linked, with the NMR analysis, it showed that glucose were existed as β-glycosidic bond with pyranose. Rhamnose were terminals-linked, and were furan type of sugar. And contained a small amount of galactose.