Structural Characterization,sulfated Modification And Hypoglycemic Activity Of Polysaccharide From Inonotus Obliquus

The biological activity of polysaccharides is related to the structure.Therefore,the structural modification of polysaccharides can change the biological activity of polysaccharides.In this paper,two extraction methods were used to fully extract the fruiting body polysaccharide of Inonotus obliquus.The structural characterization and in-vitro hypoglycemic activity of polysaccharides and the sulfation of polysaccharides were investigated.The main research results are listed as follows:?1?The isolation and purification of the crude polysaccharide extracted from the fruiting body of Inonotus obliquus were studied.The results showed that both NIOP1-S and HIOP1-S were homogenous components.With the average molecular weight of 36765 Da,NIOP1-S consisted of mannose,rhamnose,glucose,galactose,xylose,and arabinose,and the monosaccharide molar ratio was 0.23:0.17:1.31:4.56:0.44:1.HIOP1-S was composed of mannose,rhamnose,glucose,galactose,and arabinose,with a monosaccharide molar ratio of0.55:0.29:4.85:9.37:1,whose average molecular weight was 32681 Da.Infrared and¹H-NMR results indicated that both NIOP1-S and HIOP1-S were?-pianos.?2?Two different in-vitro experiments were used to study the hypoglycemic activity and mechanism of NIOP1-S and HIOP1-S.The results showed that compared with the acarbose group,the inhibition rate of NIOP1-S and HIOP1-S was higher.The IC₅₀0 of NIOP1-S,HIOP1-S,and acarbose were 24.22,29.95,and 1020?g/mL,respectively.In addition,it was found that NIOP1-S was a non-competitive inhibitor and HIOP1-S was a competitive inhibitor.HepG2 cells were used as a receptor model to study the effects of polysaccharides on glucose consumption in normal cells and the insulin resistance cells.Compared with the control,both NIOP1-S and HIOP1-S couldincrease the glucose consumption of HepG2 cells within the range of safe administration?10-100?g/mL?.Among them,the highest glucose consumption was obtained when NIOP1-S was at a concentration of 25?g/mL and HIOP1-S was at a concentration of 50?g/mL,and the effect was better than the experimental insulin group(10^-8mmol/L)and metformin group?10^-33 mmol/L?.Compared with the normal control group,the glucose consumption of the model group?IR?induced by high insulin was significantly reduced,indicating that the insulin resistance model was successfully established.Compared to the IR group,the metformin group?10^-33 mol/L?,the NIOP1-S sample group?10-100?g/mL?,and the HIOP1-S sample group?10-100?g/mL?can promote the glucose consumption of insulin resistant HepG2 cells.And when NIOP1-S was at a concentration of 25?g/mL and HIOP1-S was at a concentration of 50?g/m L,the glucose consumption of insulin resistant HepG2 cells was significantly increased.?3?S-NIOP1-S and S-HIOP1-S,the sulfated polysaccharides,were obtained by using chlorosulfonic acid-pyridine method.The corresponding modification groups appeared in the infrared images of S-NIOP1-S and S-HIOP1-S,indicating that the sulfation was successful.And the UV absorption was showed that the sulfated polysaccharides did not appear new absorption peaks.The results of?-glucosidase inhibition of S-NIOP1-S and S-HIOP1-S showed that the?-glucosidase inhibition rates of S-NIOP1-S and S-HIOP1-S were higher than those of unmodified at the same concentration.Among them,the IC₅₀0 of NIOP1-S and HIOP1-S was reduced by 2.5 times and 1.95 times respectively.The study found that the introduction of sulfuric acid groups had a toxic influence on HepG2 cells,while the safe administration range of S-NIOP1-S and S-HIOP1-S was 10-50?g/mL.To investigate the effects of S-NIOP1-S and S-HIOP1-S on glucose consumption in HepG2 cells,we found that when the concentration of S-NIOP1-S was 10?g/mL and the concentration of S-HIOP1-S was 10-25?g/mL,sulfation can increase the glucose consumption of HepG2 cell.However,with the polysaccharide concentration increasing,the sulfate group concentration also increased as well,and meanwhile the sulfated modified polysaccharide reduced the glucose consumption of HepG2 cells.This showed that high concentration of sulfate groups was not conducive to enhance the glucose consumption of HepG2 cells.