Isolation, Purification, Structure Characterization And Hypoglycemic Activity Analysis Of Lycium Barbarum Leaf Polysaccharides

In recent years,diabetes is one of the chronic diseases endangering human health.The main causes are the lack of insulin or its biological damaged effect.In modern society,more and more insulin or oral drug therapy(eg:sulfonylureas and metformin drugs)are used to alleviate symptoms and treat of diabetes.However,long-term administration of chemical synthesis drugs can lead to side effects to human body.A large number of studies showed that natural ingredient was a safe and feasible way to develpment hypoglycemic drugs.And studies indicated that antioxidation is related to hypoglycemic.So in this paper,ultrasonic-microwave combined extraction(UMCE)process was optimized by response surface method(RSM).After Molish test,Fehling test,I-KI test,the extract was identifited as polysaccharide substance.The purified Lycium barbarum leaves polysaccharides(LLP)was graded,then its structure was explored by scanning electron microscope(SEM),FTIR Spectrometer and Circular Dichroism(CD)method.The PMP-HPLC method was used for determination of the monosaccharide composition of LLP.In addition,the antioxidant activity and hypoglycemic activity of LLP was studied,it provided a basis for the Lycium barbarum leaves as resist lipid peroxidation and the development of natural hypoglycemic food.Firstly,UMCE conditions are optimized and its mechanism is preliminary explored.Compared to traditional hot water bath heating method(HWE),microwave assisted extraction(MAE),ultrasonic assisted extraction(UAE),UMCE method significantly improved the extraction yield of LLP.This method possessed the advantages of ultrasound and microwave.Water extract-alcohol precipitation repeatedly and Sevage method was used for polysaccharide purified.Then LLPs was graded by ethanol,respectively LLP30,LLP50 and LLP70.And the molecular weight of LLPs was determined through ubbelohde viscometer.The study found that the monosaccharide composition and content of LLPs were not identical,LLP30 contained mannose,rhamnose,galacturonic acid,glucose,galactose and arabinose,the highest content was galacturonic acid.The galacturonic acid and arabinose were main monosaccharide composition in LLPs,LLP30 had higher monosaccharide content than others,but its galactose levelwas below than LLP50.Secondly,ABTS·+?DPPH·?O2-and·OH was used to analyze antioxidant activity of LLPs in vitro.The a-glycosidase enzymes and a-amylase was studied for hypoglycemic activity in vitro.Results showed that LLP had strong ability on ABTS,DPPH,O2-and OH radical,including LLP50 and LLP30 was stronger.And LLPs had inhibition on alpha effect on a-glycosidase enzymes and a-amylase.Among them,the LLP50 had the stronger inhibition ability.Thus LLP50 was selected for feeding diabetes mice which was caused by STZ.Thirdly,the result of its daily water quantity,food intake,weight value and blood glucose levels,found that high concentrations of LLP can significantly lower the blood glucose levels of diabetic mice.The mice's serum,liver and kidney was usedto study the superoxide dismutase(SOD)and catalase(CAT)activity,glycosylated serum protein(GSP)and the content of serum insulin in vivo.The result showed that 800 mg/kg dose of LLP50 can significantly increase the content of serum insulin,and decrease the content of GSP in serum,it can also maintain the diabetes mice organs and serum enzyme vigor.Finally,based on the LLP had hypoglycemic and antioxidant activity,thus we developed a LLP auxiliary hypoglycemic lozenges,it met the national food safety standards.