Study On The Extraction And Treating Alzheimer’s Disease Model Mice Of Polysaccharides From Schisandra Chinensis Leaf

Objective The crude polysaccharides of Schisandra chinensis Leaves was extracted.We studied the effect of Schisandra chinensis polysaccharide on Alzheimer’s disease（AD）model mice.The mechanism of action of Schisandra chinensis Leaves polysaccharides in the treatment of AD was explored,which provided a theoretical basis for the development and utilization of Schisandra chinensis Leaves.Methods（1）Crude polysaccharide were obtained by reflux extraction method.Based on the single factor experiment,the influence of three factors on the extraction yield of crude polysaccharide was investigated.The best extraction process of crude polysaccharide was optimized by Box-Behnken response surface analysis method.The crude polysaccharide was deproteinized to obtain Schisandra chinensis leaves polysaccharide（SCLP）.（2）The content of total sugar,uronic acid and protein of SCLP was determined by UV spectrophotometer.The chemical bonds or functional groups of SCLP were analyzed by infrared spectroscopy（FT-IR）.The average molecular weight of SCLP was determined by GPC/SEC-MALS.The monosaccharide composition of SCLP was determined by thin layer chromatography.The thermal stability of SCLP was analyzed by DSC.The crystal structure of SCLP.was determine by XRD.（3）The total reducing power of SCLP and the clear rate of DPPH·,ABTS⁺·,·OH^-,and·O₂^-were determine to assess antioxidant capacity by spectrophotometry.The EC₅₀of scavenging rate of each free radical of SCLP was calculated and analysis antioxidant capacity of SCLP.（4）The AD model of BABL/c mice was established by aluminum trichloride（Al Cl₃）combined with D-galactose（D-gal）.The diversification in learning and memory ability of mice were detected by MWM and NOR.The contents of TNF-α,IL-1,Aβ,ZO-1 and D-Lac were determined.The expressions of BACE1 and AMPK in the hippocampus of AD mice were detected by Western blot.The microorganisms in the feces of mice in each group were analyzed by 16S r RNA gene diversity sequencing to explore the mechanism of SCLP on the treatment of AD mice.Results（1）The best extraction craftsmanship of crude polysaccharide was described as:the liquid-solid ratio as 31:1（m L/g）,the extraction time as 245 min,the extraction temperature as 81℃,and the yield of crude polysaccharide from Schisandra chinensis leaves is 7.08%.（2）The total sugar content is 65.21±2.15%,the uronic acid content is16.42±1.65%,the protein content is 5.61±0.51%.FT-IR indicated that SCLP contained characteristic absorption peaks of polyhydroxy aldose.The weight-average molecular weight（Mw）was 2.21×10⁶Da.The monosaccharide composition of SCLP contain Glu,Gal,Rha,Xyl,Ara,Man,Glc A,Gal A and Rib.X-ray showed that SCLP was an amorphous polymer.DSC showed that SCLP had good thermal stability.（3）SCLP can effectively capability of free radicals and there is a significant dose-effect relationship.The EC₅₀values were 0.735 mg/m L,0.626 mg/m L,1.677 mg/m L,and 0.253 mg/m L,respectively.The results showed that it has a certain antioxidant activity in vitro.（4）Behavioral tests showed that it could improve the learning and memory ability of AD mice.SCLP could reduce the levels of TNF-α,IL-1 and Aβin serum,ameliorate the inflammation and amyloidβdeposition in AD mice,inhibit the expression of BACE1 and increase the expression of AMPK in the hippocampus.The results of 16S r RNA sequencing showed that compared with the blank group,the intestinal flora of AD mice was disordered,but SCLP could regulate the structural composition and function of the intestinal flora of AD model mice.Conclusion In this paper,the optimal process for extracting crude polysaccharides from Schisandra chinensis Leaves is obtained through single factor investigation and BBD.It is found that SCLP has antioxidant activity.In addition,it is found that SCLP can regulate the intestinal flora and the gut-brain axis,inhibiting the expression of BACE1.and elevating expression of AMPK to treat AD model mice.In conclusion,it provides a scientific foundation for reasonable development and take advantange of non-medicinal resources of Schisandra chinensis and the prevention and treatment of AD.