Study On The Screening And Preparation Of The Auricularia Auricular Polysaccharide Simulated Hydrolysate And Its Hypoglycaemic Effect

In this paper,the influence of materials' origin,extraction methods on the bioactivity of Auricularia auricular polysaccharide were investigated.AAOS,which was obtained by in vitro digesting of Auricularia auricular polysaccharide,had been used to study its hypoglycemic effect.What's more,the spectral analysis of the main groups which were purificated from AAOS.The main conclusions are as follows:1.The biological activities of polysaccharide(DDA,DXA,SXA,HSA,ZJA)extracted from different varieties of Auricularia auricular,which were respectively produced in Daxing'an Mountain range,Yichun,Shaanxi,Anhui and Zhejiang,were different.The results indicated that Auricularia auricular produced in Shaanxi had the highest yield of crude polysaccharide,53.02±1.32%;DXA showed the strongest antioxidant ability in vitro(DPPH radical-scavenging effect,hydroxyl radical-scavening effect,superoxide radical-scavenging effect,metal chelating ability,reducing power);DDA had the strongest antioxidant capacity(Caenorhabditis elegans' lifespan,oxidative stress,SOD/CAT activity and ROS level)and?-glucosidase inhibition ability.Comprehensive consideration,the Auricularia auricular produced in Heilongjiang is better than the other varirties to prepare polysaccharide.2.Extraction processes of polysaccharide had effect on the biological activities of polysaccharide.Among hot water extraction,enzyme extraction and alkali extraction,alkali extraction had the highest yield of crude polysaccharide;Auricularia auricular polysaccharide extracted by enzyme extraction showed the strongest antioxidant capacities in vitro(DPPH radical-scavenging effect,hydroxyl radical-scavening effect,superoxide radical-scavenging effect,metal chelating ability,reducing power)and ?-glucosidase inhibition rate.But there was no significant difference between enzyme extraction and alkali extraction on ?-glucosidase inhibition rate(p>0.05).And the Auricularia auricular polysaccharide extracted through alkali extraction showed better antioxidant activity in vivo in C.elegans.Comprehensive consideration,the enzyme extraction is more suitable for thepreparation of Auricularia auricular polysaccharide.3.In vitro digestion procedure of Auricularia auricular polysaccharide was simulated with artificial gastric juice and artificial intestinal fluid.And then the rules of biodistribution of Auricularia auricular polysaccharide was understood.At 5min,Auricularia auricular polysaccharide was start to be degraded.Meanwhile,the level of reducing sugar increased rapidly;after 20 min,the speed slowed down and the retention time of peak on HPLC chromatograms was no longer changing.In addition,after digestion in the gastric juice for 30 min,the content of reducing sugar in the hydrolysate was no longer increased.There was no new compound appear.Results suggested that the Auricularia auricular polysaccharide in artificial gastric juice,20 min has been already degraded,and there was no further degradation in artificial intestinal juice.And then the hydrolysates of Auricularia auricular polysaccharide(AAOS)was prepared according to the above conclusion.AAOS was mainly composed of mannose,glucosamine,glucose,galactose,xylose,arabinose with the molar ratio of 1.89:0.23:1.00:0.13:0.56:1.00.4.Establishing the model of type 2 diabetes was by intraperitoneal injection of streptozotocin(STZ)to rats.Diabetic rats were induced by long-term administration of AAOS,and the changes of morphology,body weight and blood glucose were dynamically monitored.Compared with the negative group,the weight loss of the polysaccharide group was smaller.And the symptoms of diabetes had been improved.What's more,the blood glucose decreased significantly after seven weeks(P<0.05).After that,in sugar tolerance test(GTT),the level of glucagon like peptide 1(GLP-1)in polysaccharide group increased significantly when compared with negative group.At 60 min,the blood glucose reached to the highest level,while at 120 min down to the initial level.This shows that AAOS can improve the regulation of blood glucose by promoting the secretion of GLP-1 in STZ diabetic rats.,There was significant difference between polysaccharide group and negative group on the activities of SOD,CAT and GR in serum(P<0.05,P<0.05,P<0.01).In polysaccharide group,the levels of TG,LDL-C in serum significantly decreased(P<0.01);the levels of insulin in pancreatic,liver glycogen content had been significantly increased(P<0.01).This shows that AAOS can improve the antioxidant related enzymes activities in diabetic rats,enhance the ability of radicals-scavenging,regulate lipid metabolism,promoteinsulin secretion and liver glycogen synthesis.It can play a role in reducing blood glucose.At the same time,AAOS prolonged the lifespan of C.elegan in high glucose environment.It means that AAOS can reduce the damage caused by high glucose.5.The four main groups were separated and purified by Sephadex G-100 column from AAOS,labeled as AAOS1,AAOS2,AAOS3 and AAOS4.There were no absorption peak of protein and nucleic acid in UV spectral.The average molecular weights of these four groups were 320627 Da,169044Da,61944 Da,5689Da,respectively.According to the 13C-NMR of AAOS1 and AAOS2,the two components have the similar structure.The primary key of their molecules was?-1?4 glycosidic bond.And there may have ?-Glc(1?4)-,?-xyl(1?4)-,?-xyl(1?3)in C-1.C-6 in AAOS1 or AAOS2 was connected with branched side chains.And AAOS1 may have methyl groups in C-6.In AAOS2,one of these positions(C-2,C-3,C-4)was substituted.