Studies On Extraction,Purification And Bioactivity Of Extracellular Polysaccharide From Tricholoma Mongolicum Imai

Tricholoma mongolicum Imai is a large-scale fungus,medicinal and edible.It is always famous for its good taste and rich nutrition.Polysaccharide is one of the T.mongolicum Imai main active substances and has important research value.The extreacellular polysaccharides was extracted from fermentation solutions of T.mongolicum Imai by alcohol preciption.Later,enzymation,gel column and ion exchange column were applied to isolate and purify the crude polysaccharides.After that the structure identifications of pure polysaccharides were conducted by the combination of UV-Vis,GPC,GC-MS and FTIR.As it turns out,the optimum process of alcohol precipitation was determined as follows: temperature was 8℃,time was 36 h,ethanol concentration was 85%.Meanwhile,the optimal protein removal conditions were: enzyme addition 0.31%,pH 7.0,temperature 49.0℃,time 1.40 h.Under the mentioned process,the polysaccharide retention rate was 80.81%,along with the protein removal rate was 80.52%.In addition,two pure polysaccharides,TMMEP-1 and TMMEP-2,were obtained,with molecular weights of 273816 D and 86656 D.Furthermore,the monosaccharide composition of TMMEP-2 was detaily discussed.TMMEP-2 was composed of ribose,arabinose,xylose,mannose,glucose and galactose.Its molar ratio was 0.23:0.41:3.64:1.84:1.47:1.88.Further comprehensive evaluation of its bioactivity including antioxidant,hypoglycemic activity and bacteriostasis,were also demonstrated and results are as follows: in vitro scavenging free radicals to determine the antioxidant activity of TMMEP-2,indicating that TMEMEP-2 has strong hydroxyl radicals and the DPPH· free radical scavenging capacity reached 71.02% and 45.01%,respectively.The reducing power of TMMEP-2 is not high.Animal experiment to determine the hypoglycemic activity of TMEMEP-2: TMEEP-2 has hypoglycemic effect,can reduce the fasting blood glucose value of diabetic mice,improve the glucose tolerance effect and have a certain mitigating effect on liver damage caused by diabetes.The Oxford Cup antibacterial experiment found that TMMEP-2 had no obvious antibacterial activity against Escherichia coli,Staphylococcus aureus,Penicillium expansum,Aspergillus niger and Saccharomyces paradoxus.