Research On Hypoglycemic And Hypolipidemic Effects And Mechanism Of Cellulose Nanocrystals From Sweet Potato Residues

Cellulose nanocrystal is prepared by acid degradation, with natural cellulose or microcrystalline cellulose as raw material. It not only has the basic structure and properties of the fiber, but also has the characteristics of nanoparticles. The research about cellulose nanocrystal is less at home and abroad, mainly in the preparation and physicochemical properties, and the reports of cellulose nanocrystal in physiological function is not yet. With cellulose nanocrystal prepared from sweet potato residue fiber as raw material, the research was on hypoglycemic and hypolipidemic effects and mechanism of cellulose nanocrystals from sweet potato residues and its functional properties. It is provide theoretical basis for actual application and the further research.The main conclusions of the research are as follows:(1) This study was to investigate the effects of nanocrystallization process on the various functional and physiological properties of cellulose from sweet potato residues. With sweet potato residue as raw material, preparation of raw cellulose, microcrystalline cellulose, and cellulose nanocrystals, to measuring the adsorption capacity of cholesterol, bile acid sodium and oil, cation exchange capacity, glucose binding ability, alpha amylase and pancreatic lipase activity inhibition, viscosity, and infrared spectrum measurement. The results show that as particle size of cellulose decreased, the adsorption capacity of cholesterol, bile acid sodium and oil, cation exchange capacity, glucose binding ability, alpha amylase and pancreatic lipase activity inhibition, and viscosity were increased. However, cellulose naonocrystals showed the highest adsorption capacities, cation-exchange capacity, glucose binding ability, alpha amylase and pancreatic lipase activity inhibition, compared to the ordinary cellulose and microcrystalline cellulose. The FTIR showed chemical structure of these cellulose were no difference. These properties indicate that the nanocrystallization treatments would provide an opportunity to improve the functionality of cellulose from sweet potato residues in food applications.(2) The research was on hypolipidemic effects and mechanism of cellulose nanocrystals from sweet potato residues in Diabetic Rats. Forty mature male SD rats were divided into five groups. One group was fed with basic forage as control group (CON). The other four groups were given intraperitoneal injection of streptozotocin (STZ) to establish diabetic rat model. They were fed with basic forage and dietary fiber, assigned as model control (MC), ordinary cellulose (OC), microcrystalline cellulose (MCC) and cellulose nanocrystals (CNC). Compared with those of control group, the feed intake, fasting plasma glucose, glycosylated serum protein, and serum lipids of model control were significantly higher (P< 0.05), and their body weight, insulin and the content of hepatic glycogen obviously declined (P<0.05), the insulin shape changed. The results suggest the diabetic model was successfully built. Feeding different granularity of sweet potato residues fiber to diabetic rats resulted in their weights, serum insulin, glycogen levels and the expression of liver GK and PPAR-y increased, original and fasting glucose, glycosylated serum protein, blood fat and the expression of liver GLUT2, G6Pase and PEPCK decreased. However, Feeding cellulose nanocrystals diabetic rats were significantly changed (P<0.05). And the expressions of liver GK and PPAR-y were significantly increased. It showed that cellulose nanocrystals from sweet potato residues can effectively regulate the levels of blood glucose and serum lipid. The hypoglycemic mechanism may be by slowing down the body’s absorption of glucose, reduce fasting blood glucose value, improve the glucose tolerance, at the same time increase the body’s sensitivity to insulin and insulin secretion, promote the synthesis of liver glycogen, adjust the balance of glucolipid metabolism in the liver.(3) Diabetes has the influence on the intestinal environment. Research on the effect of cellulose nanocrystals on gut environment of diabetic rats, and analyze its correlation with the effects of hypolipidemic in diabetic rats. Forty mature male SD rats were divided into five groups. One group was fed with basic forage as control group (CON). The other four groups were given intraperitoneal injection of streptozotocin (STZ) to establish diabetic rat model. They were fed with basic forage and dietary fiber, assigned as model control (MC), ordinary cellulose (OC), microcrystalline cellulose (MCC) and cellulose nanocrystals (CNC). Results show that the cecum, cecum contents and the free ammonia, harmful organisms such as the number of escherichia coli and enterococcus were increased in diabetic model group rats, while the cecum content of short chain fatty acids and beneficial microbial decreased. It indicated that the diabetes can causes the intestinal environment change, make intestines metabolic disorders. And sweet potato residue fiber can reduce the cecum contents of free ammonia and harmful bacteria diabetic, at the same time increase the cecum content of short chain fatty acid content and beneficial microbial. Cellulose nanocrystals can improve the intestinal environment and morphology on the small intestine and colon. That indicated cellulose nanocrystals can improve the intestinal environment and regulate intestinal glucolipid metabolism to improve diabetic disease.(4) Study the hypoglycemic effect and mechanism of cellulose nanocrystals. Forty mature male SD rats were divided into five groups. One group was fed with basic forage as control group (CON). The other four groups were fed with high fat diet and dietary fiber, assigned as model control (MC), ordinary cellulose (OC), microcrystalline cellulose (MCC) and cellulose nanocrystals (CNC). The results show that body weight gain, feed intake, plasma lipid, liver lipid content were significantly higher than control group (P<0.05), and lots of fat droplet in liver tissue. A high-fat diet is easy to cause hyperlipidemia. The body weight gain, feed intake, plasma lipid and liver lipid content were decreased after fed with sweet potato residue fiber. The cellulose nanocrystals can significantly reduce body weight gain, feed intake, plasma lipid, liver lipid content, and fat droplet in liver tissue. It also decease the mRNA and protein expression of SREBP-2, CYP7A1, FXR and HMG-CoA R (P<0.05) in the liver. The cellulose nanocrystals mainly through adsorption of lipids and cholesterol, reduce exogenous cholesterol, and regulating the liver lipid metabolism related gene and protein expression, reduce the endogenous cholesterol synthesis, to regulate plasma lipid and liver lipid.(5) To investigate effect of cellulose nanocrystals from sweet potato residue on intestinal histology and environment in rats fed with high fat diet, and the relation with hypoglycemic. Forty mature male Wistar rats were divided into five groups. One group was fed with basic forage as control group (CON). The other four groups were fed with high fat diet and dietary fiber, assigned as model control (MC), ordinary cellulose (OC), microcrystalline cellulose (MCC) and cellulose nanocrystals (CNC). Results:as particle size of cellulose decreased, the concentration of free ammonia and harmful bacteria were redced, the values of cecum, the concentration of short-chain acids, cecum content pH values and beneficial bacteria were raised, the change of cellulose nanocrystals was significantly (P<0.05), and improve the morphology of small intestine and colon. The cellulose nanocrystals also could significantly decrease the protain expression of ASBT, mRNA expression of ASBT and IBABP in ileum, significantly increase the content of total bile acid and neutral sterols in feces (P<0.05). It showed that cellulose nanocrystals from sweet potato residue can improve the intestinal health, adsorpt the intestinal bile acid, hinder the absorption of bile acid, and increase of the total bile acid and neutral sterols in feces excretion, to collaborative hypoglycemic.