Study On The Structure And Physicochemical Properties Of Polysaccharides From Pholiota Nameko

Pholiota nameko(Pholiota nameko Ito ex Imai),also known as Pheliota nameko,is one of the main active ingredients of Pheliota nameko,which has a variety of functions and has high nutritional value and economic value.In this paper,using modern separation and purification technology,several components were extracted from the mushroom,and their physicochemical properties,structural characteristics and biological activities were systematically studied.The following experimental results were obtained:Five polysaccharide components,RTSP,BWSP,HPSP,WBSP and SASP,were extracted from Pheliota nameko by means of water extraction at room temperature,hot water extraction,high pressure extraction,0.125 mol/L Na OH and 1.25 mol/L Na OH.The physical and chemical properties and solution behavior of the five polysaccharides were further studied by chemical and spectroscopic methods.The total sugar contents were 53.46%,78.19%,86.91%,84.24%and 95.21%,the protein contents were 5.41%,0.40%,1.32%,1.99%and 1.88%,and the uronic acid contents were 2.41%,0.42%,1.31%,1.89%and 0.87%,respectively.X-ray diffraction patterns showed that RTSP,BWSP and HPSP could not form polysaccharide monomers,and WBSP and SASP were amorphous structures.The thermal analysis results show that RTSP,BWSP and HPSP have better thermal stability,while WBSP and SASP have poor thermal stability.The structure and solution behavior of the alkali-extracted components WBSP and SASP were further analyzed.High performance size exclusion chromatography-multi angle laser light scattering(HPSEC-MALLS)analysis showed that the molecular weights of WBSP and SASP were 3.58×10~5 and 8.45×10~6Da,respectively.g/mol,mean square radius(Rg)are 50.6 nm and 248.3 nm,polydispersity index(Mw/Mn)are 2.341and 1.593,respectively.The NMR spectrum shows that the two components are based on?3)-?-D-Glcp-(1?as the main chain,with side chains?6)-?-D-Glcp-(1?.Congo red experiments show that the two groups SASP has a triple helix structure.The critical concentrations of WBSP and SASP in aqueous solution are 0.94 g/and 0.86 g/d L,and the intrinsic viscosities are 1.136 d L/g and 0.394 d L/g,respectively.rheological analysis shows that the two alkalis,the viscosity of the extraction component is affected by concentration,stress and metal ions.During the temperature and frequency scanning process,both components show weak gel characteristics.The polysaccharide BWSP obtained by hot water extraction method was separated and purified by ion exchange chromatography,and two homogeneous components BWSP-1 and BWSP-2 were obtained,and the structure and immunological activity of these two components were characterized.The experiment results show that the relative average molecular weights of BWSP-1 and BWSP-2 are 6.99×10~5 Da and 7.78×10~5 Da and the neutral sugar content is 96.53%and 94.06%,respectively.BWSP-1 mainly contains xylose,mannose and glucose.The molar ratio of the three monosaccharides is0.235:1:0.117 respectively.The main chain consists of the main chain?6)-?-D-Manp-(1?,?3,6)-?-D-Manp-(1?and?4)-?-D-Glcp-(1?composition,in the O-3 upper link of?6)-?-D-Manp-(1?Branched-chain?-D-Xylp-(1?.BWSP-2 mainly contains xylose,mannose and glucose.The molar ratio of the three monosaccharides is0.262:1:0.096 respectively.The main chain consists of?3,6)-?-D-Manp-(1?,?6)-D-Manp(1?and?4)-D-Manp(1?composed,branched by?4)-?-D-Xylp-(1?and?3,6)-?-D-Manp-(1?O-3 is connected.The physical and chemical properties show that the two components have good heat Stability,X-ray diffraction shows that these two components are very weak in crystallinity and belong to semi-crystalline polymers.It is observed through scanning electron microscopy and atomic force microscopy that some molecules of BWSP-1 are in a polymerized state,and the distribution of BWSP-2 is more uniform.The antioxidant activity analysis showed that RTSP,BWSP,HPSP,WBSP and SASP had good scavenging ability on DPPH radical and hydroxyl radical.When the concentration of polysaccharide reached 5 mg/m L,The scavenging ability of DPPH free radical was 94.46%,86.45%,88.56%,88.35%,95.81%,and the scavenging ability of hydroxyl free radical was 57.55%,53.48%,65.54%,67.36%,57.83%,respectively.The ABTS free radical scavenging ability and Fe3+reducing ability of 5 components were weak.The results of immunoassay showed that both BWSP-1 and BWSP-2 could promote the proliferation of mouse macrophages RAW 264.7,stimulate the production of NO in macrophages,and enhance the phagocytosis capacity of macrophages.The two components had good immunomodulatory activity.