Extraction, Separation And Structural Characterization Of Polysaccharides From Neverita Didyma

Neverita didyma belongs to neverita,naticidae,mesogastropoda,mollusca,widely distributed on the coast of China.Neverita didyma is a kind of common economic seafood, whose meat not only delicious but also rich in nutrients such as protein, fat, carbohydrates, minerals and so on, has the effect of removing heat,brighting vision and nourishing the stomach and yin. In this paper,the neverita didyma power were obtained by degreasing from the fresh meat of neverita didyma which collected from seas of Yantai.The crude polysaccharides of neverita didyma were obtained by different methods and their physicochemical properties were studied,the structure of the puritied components BYL-S2was determined by modern analytical techniques,and the antioxidant activity of the crude polysaccharides were studied.The crude polysaccharides of BYL-S and BYL-J were extracted by distilled water at60℃and1%Na2CO3alkali solution at room temperature sequentially.The physicochemical properties of BYL-S and BYL-J were studied,No uronic acid,sulfate and amino sugar were found in BYL-S and its monosaccharide composition is simple,only including Glc.While BYL-J has complex monosaccharide composition,including Glc,Man,GlcN,GalN,Gal and Fuc,and their molar ratio was Glc:Man:GlcN:GalN:Gal:Fuc=78.9:1.7:3.4:2.2:5.2:5.6.Four water-soluble fractions were isolated by DEAE Sepharose FF anion-exchange (BYL-S1, BYL-S2, BYL-S3, BYL-S4),and their monosaccharide composition was Glc only.While three alkali-soluble fractions were isolated by DEAE Sepharose FF anion-exchange (BYL-J1, BYL-J2, BYL-J3),and the monosaccharide composition of them were relatively complex, they contains amino sugar, galactose, mannose,besides glucose.The molar ratio of BYL-J1is Man:GlcN:GalN:Glc Gal=1.5:2.7:1:23:4.9, the molar ratio of BYL-J2is Man:GlcN:GalN:Glc Gal:Fuc=1:4.7:1.6:10.1:2.9:8.7, the molar ratio of BYL-J3is GlcN:GlcUA GalN:Glc:Gal=12.4:1:11:10.2:9.2.The relative molecular mass of water-extract BYL-S1and BYL-S2were721and642kD, the relative molecular mass of alkali-extract BYL-J2was3.6kD,and BYL-S2was the highest purity.The structure of BYL-S2was identified by methylation method,GC-MS,infrared spectroscopy,mass spectrometry, NMR and other technologies, the data showed that the structure of BYL-S2was characterized to be composed of α-(1â†'4)-D-glucopyranose, with little β-(1â†'3,4) and β-(1â†'3) branched units.The polysaccharides of neverita didyma (BYL-S and BYL-J)possessed good antioxidant activity in vitro as evaluated by scavenging assays involving1,1-diphenyl-2-picrylhydrazyl(DPPH) and hydroxyl radical,reducing power and iron ion chelation,and the antioxidant activity of BYL-S was better than BYL-J,while their antioxidant activity were lower than Vc.At present,there was little researches on polysaccharides from neverita didyma,excepting the extraction and the contention of the polysaccharides.In the paper, The crude polysaccharides of neverita didyma were extracted by water and alkali solution sequentially, and their physicochemical properties,antioxidant activities and the structure of BYL-S were studied the preliminary study of the polysaccharides from neverita didyma providing the basis for further research on relationships of structure and activity,and comprehensive utilization of the polysaccharides.