Structure,Simulated Digestion And Immune Activity Of Expolysaccharide Of Morchella Esculenta

In this study,Morchella esculenta polysaccharide(MEP)was obtained by fermentation and extraction.After purification by chromatographic column,a homogeneous component of Morchella esculenta polysaccharide MEP 2a was obtained.Then,the primary and advance structure,changes in structure before and after in vitro simulated digestion and biological activity(antioxidation,hypoglycemic and blood lipid),cellular immune regulation,and other aspects have been studied.Structural identification of MEP 2a:MEP 2a is a homogeneous polysaccharide with a molecular weight of 139.15×10~4 Da.It is inferred that MEP 2a is a glucomannan,which is represented by→1)-β-D-Glcp-(6→,→1)-α-D-Manp-(3,4,→1)-α-D-Manp-(2→constituted as main chain,branched chain isα-D-Manp-(1→,→1)-β-D-Glcp-(6→andα-D-Glcp-(1→.The thermal stability of MEP 2a is tested by DSC and TG,which proves that MEP 2a is a stable macromolecular compound,and it will only decomposition at temperatures above 300°C.The morphology of MEP 2a was observed by SEM,and it was found that the surface of MEP 2a polysaccharide was uneven and there were many fragmented particles.It was found that MEP 2a had no triple helix conformation by Congo Red and AFM.Changes in structure and antioxidant and hypoglycemic lipid activity before and after simulated digestion in vitro:Polysaccharides did not change significantly during the saliva digestion,but the molecular weights of gastric and intestinal juice were changed to some small molecular weights.Therefore,indicating that part of the configuration of polysaccharides changes during the in vitro simulated digestion process.Through SEM and AFM,it can be observed that the MEP 2a changes from a sheet-like structure to a honeycomb-like structure after digestion by intestinal juice,which may be due to the p H and enzymes during the digestion process.The antioxidant and hypoglycemic activity of MEP 2a did not reduce its biological activity due to digestion of gastrointestinal juice.After digestion of intestinal juice,the rate of scavenging DPPH and ABTS free radicals by MEP 2a increased.As the concentration of MEP 2a increased,the inhibition ofα-amylase and the ability to bind bile salts also increased.Cell experiment to explore the immune activity of MEP 2a:MTT method experiment results show that MEP 2a is not toxic to RAW264.7 cells,and will not inhibit the growth of macrophages.Using neutral red phagocytosis experiment results showed that MEP 2a significantly increased the phagocytic activity of macrophages(p<0.01).The results of using the NO kit showed that MEP 2a significantly promote the release of NO and enhance the immunity of macrophages(p<0.05).The results of the ELISA kit showed that MEP 2a can increase the release of IL-1β,IL-6,and TNF-α,and stimulate the phagocytic activity of macrophages(p<0.05).Wb was used to detect the MAPKs protein kinase signaling pathway related to the immunoactivity of MEP 2a.The results showed that MEP 2a significantly increased the expression levels of ERK,JNK,p38and its phosphorylated proteins,and improved the immunoactivity.