Fractionation, Structure Characterization And Hypoglycemic Activity Analysis Of Selenium-enriched Chrysanthemum Selenium Polysaccharide

Selenium is an essential micronutrient for human health.Se-polysaccharide is an ideal selenium supplement.It can not only avoid the high toxicity of inorganic selenium,but also exert the efficacy of Se and polysaccharides.As the selenium valley of China,the cultivation area of selenium-enriched chrysanthemum has reached 2,000mu in Ankang city.In this study,flowers and leaves from selenium-enriched chrysanthemum were used as raw materials.A hydride atomic fluorescence spectrometry was established to quantitative analysis of selenium in chrysanthemums.Then,the physical and chemical properties,structural characterization and hypoglycemic activity of flowers and leaves from selenium-enriched chrysanthemum were preliminarily investigated.The main contents and results are as follows:(1)A hydride generation atomic fluorescence spectrometric method was developed for quantitative analysis of selenium in chrysanthemum.Selenium contents in chrysanthemum samples purchased from Shaanxi province and in different parts of Ankang selenium-enriched chrysanthemum were determined using the novel method.The optimal conditions were obtained by single factor experiments and orthogonal test:negative high voltage,320V;lamp current,85mA;and NaBH4 concentration,1.0%.System suitability test indicated that regression equation of standard curve was y=116.86x+88.69(R2=0.9998),and linear range was 10.00-100.00?g/L.LOD and LOQ were 2.60 and 7.88?g/L,respectively.Precision and mean recovery were 1.27%and 98.38%,respectively.The method is precise,accurate,sensitive,simple,safe as well as low-cost.A large variation of selenium contents was found among chrysanthemum samples from different regions in Shaanxi province,among them,chrysanthemum samples from Ankang,Xi'an and Weinan reached the selenium-rich food standard.And the selenium contents in stems and leaves of Ankang selenium-enriched chrysanthemum were relatively high,which deserved further study.(2)Se-polysaccharides from selenium-enriched chrysanthemum(CMP)and chrysanthemum leaves(CLP)by were extracted by water extraction and ethanol precipitation.According to the different molecular weights of polysaccharides,the ethanol gradient precipitation method was used to classify polysaccharides(CMP30,CMP50,CMP70,CLP30,CLP50,CLP70).The selenium content of polysaccharides was determined by hydride generation atomic fluorescence spectrometry.The best Se-polysaccharide component was screened by antioxidant tests(DPPH·,·OH,ABTS·+and reducing power)and hypoglycemic tests(inhibition of a-amylase and a-glucosidase activities).The best bioactivity component of Se-polysaccharides from selenium-enriched chrysanthemum is CMP50,the best bioactivity component of Se-polysaccharides from chrysanthemum leaves is CLP50,and the activity of CLP50 is better than that of CMP50.Then the structural characterization of these two Se-polysaccharides was identified by chromatography and other methods.It is found that the selenium content of CMP50 was 0.068?g/g and the viscosity average molecular weight was 6.13*104Da,the EC50 of DPPH·,·OH,ABTS·+were 0.47,4.35 and 3.78mg/mL,and the IC50 of a-amylase and a-glucosidase were 17.9 and 4.49mg/mL,respectively.The polysaccharides have Se-O-C characteristic absorption peak at 663cm-1,which can prove that CMP50 sure is se-polysaccharides.CMP50 has asymmetric structure in aqueous solution and may have three helix structure,the morphology of the polysaccharides could be divided into two kinds,one is porous,the other is porous,the polysaccharides could keep their structure stable in the range of 0-200'C.These structures indicate that they may have anti-inflammatory,hypoglycemic and other biological activities.The selenium content of CLP50 was 0.060?g/g and the viscosity average molecular weight was 3.05*104Da,the EC50 of DPPH·,·OH,ABTS·+were 0.1?1.84?0.89mg/mL,and the IC50 of ?-amylase and a-glucosidase were 3.27?2.71mg/mL,respectively.The polysaccharides have Se=O and Se=H characteristic absorption peak at 631cm-1,which can prove that CLP50 is se-polysaccharides.The polysaccharides exist laminated structure in aqueous solution,the morphology of the polysaccharides could be divided into four kinds,two of the polysaccharides were in the same state as CMP50,which have smooth porous surface and irregular polyporous surface,the other two were irregular mesh and regular prism.The polysaccharides could keep their structure stable in the range of 0-200?.These structures indicate that they have anti-tumor,antioxidant,hypoglycemic and other biological activities.(3)Diabetic mice models induced by streptozocin were applied to verifie the hypoglycemic activity of CLP50.Results showed that 600mg/kg CLP50 could significantly ameliorate "three more and one less" symptoms of the diabetic mice,reduce the blood glucose level of diabetic mice without causing hypoglycemic complication.It also protected liver,kidney and spleen from the diabetese induced injuries in mice.Glucose tolerance test showed that CLP50 could increase the tolerance of glucose in diabetic mice,its bioavailability was relatively high.After determining the biochemical indexes in serum and liver of mice,it was found that CLP50 could significantly increase the content of serum insulin,decrease the content of glycosylated serum protein and increase the activity of antioxidant enzymes in mice liver.CLP50 is relatively safe,non-toxic and has potential development and utilization value,although the effect of CLP50 is not as good as insulin.