Degradation,structural Analysis And Biological Activity Of Polysaccharides From Codium Cylindricum

Seaweed polysaccharides are important natural macromolecular active substances,with diverse species,widely application and multiple of biological activities.It has been widely used in the food,pharmaceutical and cosmetic industries.Codium cylindricum is a kind of green algae rich in biological nutrients and widely distributed in the coastal areas of Guangdong and Fujian.At present,C.cylindricum is mainly applied as feed and bait,and its comprehensive utilization is not high.To our best knowledge,the information about polysaccharide from C.cylindricum was limited.In this study,low molecular weight polysaccharides from polysaccharides were prepared by ultrasonics-assisted hydrogen peroxide degradation.The physiochemical properties and structural characterization of polysaccharides were studied,and the antioxidant and hypoglycemic activities of polysaccharides were evaluated.The intent of this study was to provide a theoretical reference for the development and application of C.cylindricum polysaccharides,as well as an experimental basis for the selection of polysaccharide degradation methods.The main research contents and results are as follows:1.Study on extraction,degradation and physicochemical properties of polysaccharides.Hot water extraction and alcohol precipitation was used to prepare C.cylindricum polysaccharides.C.cylindricum degraded polysaccharides were prepared by two kinds of ultrasound-assisted hydrogen peroxide degradation methods.The contents of total sugar,protein,sulfate and uronic acid of polysaccharides were determined by different methods.In addition,the solubility,viscosity,particle size and Zeta potential of polysaccharides were measured to analyze the changes of polysaccharides properties after degradation.The results showed that the total sugar,sulfate and uronic acid contents of the degraded polysaccharides were increased,while the protein content was decreased.After degradation treatment,the solubility and viscosity of polysaccharides were significantly improved.The dissolution time of polysaccharides decreased from 34.83min to 3.17 and 2.52 min at 20°C,and the viscosity decreased from 13.75 to 4.70 and3.24 Pa·s.The results of polysaccharide particle size and Zeta potential showed that the mean particle size and potential of degraded polysaccharides decreased,and the dissolution of polysaccharides tended to be dispersed.2.To characterize the structure of polysaccharides and analyze the structural differences of polysaccharides.The structure of polysaccharides was determined by ultraviolet spectroscopy,infrared spectroscopy,high performance liquid permeation chromatography,PMP pre-column derivatization-high performance liquid mass spectrometry,nuclear magnetic resonance spectroscopy,atomic force microscopy and scanning electron microscopy.The results indicated that the polysaccharides were sulphated polysaccharides,mainly composed of mannose and galactose,containedαandβglycosidic bonds.After degradation treatment,the basic structure of polysaccharides was not significantly damaged,while the molecular weight of polysaccharides decreased significantly from 50.75 k Da to 15.07 and 8.47 k Da.The results of surface morphology and apparent conformational scanning represented that the surface of polysaccharide was fragmented,the degree of molecular aggregation was decreased,and the molecular distribution was scattered.3.Study on antioxidant and hypoglycemic activities of polysaccharides.The antioxidant activity of polysaccharides was evaluated by free radical scavenging ability,and iron reducing power.The results indicated that the polysaccharide had certain antioxidant activity,which represented dose-independent manner.After degradation,the antioxidant activity of polysaccharides was significantly increased,especially the DPPH free radical scavenging activity,and the IC₅₀ value decreased from 3.854 to 1.161 mg·m L^-1 and 0.5515 mg·m L^-1.The results showed that the polysaccharide had a certain hypoglycemic activity,which inhibitedα-amylase andα-glucosidase.Degradation treatment could effectively improve the hypoglycemic activity of polysaccharides,and the order of the inhibition ofα-amylase andα-glucosidase of the three polysaccharides was consistent with the results of antioxidant activity in vitro.