Study On Extraction,structure And Activity Of Nostoc Sphaeroids Kütz Polysaccharide

Nostoc sphaeroids kütz is a kind of blue-green algae of the Chinese medicine and food,which has the efficacy of bright eyes,clearing heat and benefit bowel.In recent years,with the artificial cultivation technology has tended to perfect,it was used in the food,health care products and cosmetics.In recent years,with the artificial cultivation technology has tended to perfect,it was used in the food,health care products and cosmetics.Polysaccharide is the main active ingredient in Nostoc sphaeroids kütz but the research on the polysaccharide determination methods,structure characteristics and biological activity was lacked.So this research established the polysaccharide determination methods by colorimetric method and HPLC method,the physicochemical properties,structure,moisture and immunity of the polysaccharide were analyzed,the main results are as follows:The optimization conditions of extraction process of the polysaccharide was 100?of water bath,6 hours of heating time,1:500 of liquid ratio,the content could reach up to 32.65%by the phenol-sulfuric acid method.Methodology indicated the determination results were high precision,good reproducibility and color stability.The polysaccharide was determine by High Performance Liquid Chromatography?HPLC?result showed that the macromolecular polysaccharide could be effectively measured by TSK-Gel G6000 PW_XL,peak area showed a good linear relationship in the range of0.15625⁵mg/mL;The precision,rrepeatability and stability of the relative standard deviation?RSD?were 1.59%,1.13%and 2.56%,the average recovery rate was 97.8%and RSD was 1.72%,indicating that the method has high sensitivity,repeatability and stability well,so HPLC method is suitable for determining macromolecular polysaccharide content.The polysaccharide was obtained by graded and repeated ethanol precipitation extraction,The weight average molecular weight?Mw?of NSKP40?40%ethanol?is1.31×10⁵ Da,which is made up of galactose,glucose,xylose,mannose and glucuronic acid in a molar ratios of 1.00:1.92:0.97:1.02:0.91,respectively.Using reduction of uronic acid,FTIR,methylation,nuclear magnetic resonance spectroscopy?NMR?and acid degradation to analyse the structure,the results show that the NSKP40?40%ethanol?is mainly composed of Terminal-Gal-?Terminal-GlcA-?-4-Man-1??-4-Xyl-1??-3,4-Glc-1??-4,6-Glc-1?and its chemical structure as follows:Using MCR-302 type rotary rheometer to investigate the rheological properties of the polysaccharide NSKP40?40%ethanol?,result showed the apparent viscosity is influenced by temperature,concentration,pH,antioxidants and oxidants.The polysaccharide solution was pseudoplastic non-Newtonian fluid with shear thinning properties;The viscosity of polysaccharide solution increased with the increasing concentration;in the range of 20⁸0?,the viscosity of polysaccharide solution decreased with the increase of temperature;The viscosity of polysaccharide solution at pH=3.0 or pH=11.0 was lower than pH=7.0;VC and H₂O₂ could reduce the viscosity of polysaccharide solution,but the decline extent of viscosity was not related to the concentration of VC.The storage modulus?G??and loss modulus?G???increased with increasing concentration of polysaccharide solution in scanning frequency 0.1¹0 Hz.In addition,The polysaccharide had synergistic thickening interaction with hyaluronic acid.In different relative humidity?43%and 81%?conditions,the polysaccharide had moisture absorption and moisture retention,and the moisture retention rate of high molecular weight polysaccharide was better than hyaluronic acid.Compared with the LPS stimulation control group,it could accelerated the NO release of model cells,and NSKP40 showed significant immuno at low concentration 50?g/mL.Therefore,the polysaccharide may exert the bioactivity of immunomodulatory by an inhibition of the production of NO from macrophages models.