| Chinese water chestnut(Eleocharis dulcis)is a kind of aquatic plant belonging to the family of sedges which usually refers to the edible corms.The peels are the by-products of the procession of Chinese water chestnut,which comprise approximately 20%(w/w)of the corms.However,the peels discarded or as feed are not utilized thoroughly with low economic value.Polysaccharide is a kind of bioactive composition with antioxidant,immunomodulatory,hypoglycemic and anti-tumor effect,showing potential in weight control,immunity improvement and tumor prevention.Polysaccharide is also an important component in Chinese water chestnut peels.However,the structure and activity research about polysaccharides in Chinese water chestnut peels is not enough.According to the situation,this research purified,characterized and studied the bioactivities and propertites of polysacchardies in Chinese water chestnut peels.The main approaches and results of this research are listed as follow:(1)The carbohydrate,protein,lipid,polyphenol and flavonoids contents in Chinese water chestnut peels were 25.04%,0.57%,0.13%,1.93%and 2.19%,respectively.After extraction and removal of other compositions,the yield of crude polysaccharide WP was 1.20%.The major purified compositions WVP-1 and WVP-2were obtained after DEAE-Sepharose Fast Flow and Sephadex G-75 seperation.The carbohydrate contents of WVP-1 and WVP-2 were 95.03%and 91.61%,respectively without protein and endotoxin detected.Besides,the sulfuric acid-carbazole assay indicated that the uronic acid content of WVP-2 was 9.20%,which belonged to acidic polysaccharide with a possible pectin structure.(2)In HPGPC,the Mw of WVP-1 and WVP-2 was 3.16 and 56.97 k Da respectively.XRD patterns indicated that WVP-1 and WVP-2 were mainly characterized as amorphous forms.In TG-DSC analysis,Tg of WVP-1 and WVP-2was 61.3 and 69.5?,while decomposition temperature of WVP-1 and WVP-2 was290.5 and 308.5?,respectively.Thus,WVP-2 exhibited better stability of storage and thermal procession.The Zeta potential of WVP-1 and WVP-2 was 9.6 and-18.5mV and the absolute value of WVP-2 solution was higher with better stability.The intrinsic viscosity of WVP-1 and WVP-2 was 5.3×10-3 and 3.8×10-2 mL/mg.In consideration of the results of FT-IR,WVP-2 was a pectin-like polysaccharide and the degree of esterification was 15%.(3)According to the results of HPLC,WVP-1 mainly contained mannose(1.75%),glucose(84.69%),galactose(6.32%)and arabinose(7.24%).WVP-2 was mainly composed of mannose(3.18%),rhamnose(1.52%),glucuronic acid(1.42%),galacturonic acid(4.83%),glucose(11.51%),galactose(36.02%)and arabinose(41.53%).The FT-IR sprctra indicated that both WVP-1 and WVP-2 contained furan and pyranose rings mainly as?-configurations.In Congo red assay,it possibly exhibited a triple helical strcture both in WVP-1 and WVP-2.WVP-1 contained 9types of linkage,among which?-D-Glcp-(1?and?4)-?-D-Glcp-(1?accounted for higher proportions,while WVP-2 contained 12 types of linkage and the backbone consisted of?4)-?-L-Arap-(1?and?3)-?-D-Galp-(1?.In addition,?4)-?-D-Galp A6Me-(1?was detected.WVP-1 consisted of linear and branched polysaccharides simultaneously and WVP-2 was a low uronic acid and DE pectin-like polysaccharide with HG region.(4)The ORAC values of WVP-1 and WVP-2 were 5.1±0.10 and 27.6±0.01?mol Te/g.WVP-1 and WVP-2 could effectively inhibited increase of ROS level in Hep G2cells and at the range of 125?250?g/mL,the inhibition effect of WVP-2 was stronger than that of WVP-1.At the range of 62.5?1000?g/mL,WVP-1 and WVP-2 protected erythrocyte away from oxidative hemolysis induced by AAPH and the best effect appeared at the concentration of 500?g/mL.However,when the concentration was blow 1000?g/mL,the scavenging rate of DPPH·was blow 10%for WVP-1 and WVP-2.WVP-2 exhibited a stronger capacity as antioxidant.(5)62.5?1000?g/mL WVP-1 and WVP-2 were nontoxic to RAW 264.7 cells.The higher the concentration of WVP-1 and WVP-2,the more strongly RAW 264.7cells phagocytosed FITC-labled E.Coli.Both WVP-1 and WVP-2 exhibited a capacity to induce RAW 264.7 cells to produce NO,IL-6 and TNF-?and the capacity of WVP-2 was siginificantly better(p<0.05)at various concentrations.Thus,polysaccharides in Chinese water chestnut peels played a potential role in immunomodulatory activity. |
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