Study On Hypoglycemic Activity Of Aqueous Extract From Inonotus Obliquus

Inonotus obliquus is a very rare medicinal fungus.The efficacy of its"anti diabetes"properties has been widely recognized,but there is a lack of systematic research on its composition and hypoglycemic mechanism.Inonotus obliquus was chosen as the research object,the polysaccharide extraction,component analysis,antioxidant activity and the hypoglycemic effect and mechanism were studied.This was done to establish a theoretical basis and reference for the application of this valuable medicinal fungus in the treatment of diabetes mellitus.The main research results are as follows:（1）The Inonotus obliquus polysaccharide extraction conditions were optimized by response surface methodology.The optimum process parameters were:2 hours at 100℃,with a solid to liquid ratio of 24:1.The theoretical polysaccharide yield under these conditions was 2.84%.The experimental test result was 2.78%.According to the variance analysis,it is concluded that the influence of each factor decreased in the following order:extraction temperature>solid-liquid ratio>extracting time.（2）Three crude polysaccharide fractions from different levels were obtained by ethanol precipitation.The nutrient components and antioxidant activity（DPPH,ABTS,hydroxyl radical,reducing power and total antioxidant capacity of FRAP）were analyzed.The antioxidant activity of each crude polysaccharide decreased in the following order:PP80>PP60>PP30.（3）PP30 showed the bestα-glycosidase inhibitory activity.PP30was hydrolyzed with TFA,reduced with NaBH₄ and acetylated with acetic anhydride.GC analysis indicated that PP30 was composed of rhamose,arabinose,xylose,mannose,glucose and galactose.（4）Four methods for removing proteins from PP30 were compared.The Sevage method for removing protiens was selected.Under the same conditions,theα-glycosidase inhibitory activity of Inonotus obliquus polysaccharide with no protein decreased.Therefore,it is inferred that there is a close relationship between good hypoglycemic effect and the existence of protein.（5）Aiming at the molecular level,a study was conducted on theα-glycosidase andα-amylase inhibitory activity of Inonotus obliquus polysaccharide PP30.The results showed that each concentration of PP30showed inhibitory activity towardα-amylase(IC₅₀=337μg/ml).It also showed excellentα-glycosidase inhibitory activity(IC₅₀=31.5μg/ml,more than 100 times that of acarbose),and the experimental results demonstrate non-competitive inhibition.（6）In the target cells（HepG2）experiment,Inonotus obliquus polysaccharide with different concentration groups showed certain hypoglycemic effects.It can increase the glucose consumption in the culture liquid of HepG2 cells and,when combined with insulin use,a synergistic enhancement of glucose consumption of HepG2 was observed.The effect of Inonotus obliquus polysaccharide PP30 groups of different concentrations on the proliferation of HepG2 cells was not significant.A preliminary conclusion was drawn that Inonotus obliquus polysaccharide hypoglycemic mechanism may be:Inonotus obliquus polysaccharide can help to metabolise glucose in the surrounding tissue and also,strengthen the sensitivity of liver cells to insulin.