Microwave-assisted Synthesis Of Chitooligosaccharide Guanidine And Its Repairment Effect On Oxidative Damage Of Diabetic Rats

Diabetes is a metabolic disorder characterized by chronic hyperglycemia,which is caused by a variety of causes.It is a major disease that affects human life.By reference to the molecular structure of metformin(an oral hypoglycemic drug),this project used chitooligosaccharide(COS)and dicyandiamide to prepare chitooligosaccharide guanidine(COSG)with different molecular weight and different degree of substitution(DS)by microwave irradiation.Comparing with metformin and insulin,the recovery effect of COS and COSG on oxidative damage of diabetic rats was studied.Further studies of the influence of COSG on repair of oxidative damage of kidney in diabetic rats and the possible signaling pathways were also explored.First of all,COSG was prepared from COS with different molecular weight and dicyandiamide through microwave irradiation.XRD,IR and NMR were employed to analyze the structure and molecular weight of the product.Results conformed that the guanidine group was introduced into chitosan main chains.Then,the antioxidant activity of COSG was measured by scavenging capacity on DPPH free radicals.Therefore,diabetic rat model was established,taking metformin as a reference,the effect of different molecular weight of COS and preparation of different degree of substitution on oxidation injury repairmen in diabetic rats of COSG was observed.We also researched the expression level of related protein on renal oxidative injury of diabetic rats,discussing the influence mechanism of renal oxidative damage in diabetic rats.The experimental results showed that COS and the prepared COSG had better DPPH free radical scavenging effect.Compared with the model group,COS and COSG could reduce the body weight of diabetic rats by about 12%,reduce serum cholesterol in different degrees,the maximum reduction amounted to 17.25%,the largest decline in serum FFA reached 67.63%.They could significantly reduce serum GSH-Px and SOD in kidney,improve the the content of MDA,in order to improve the oxidative damage of diabetic rats.COS and COSG were likely to repair oxidative damage by decreasing the expression of PKC and TGF-β.The repairment of COSG on the oxidative damage kidney of diabetic rats has a certain dose dependent,but it has little relationship with the molecular weight.