Hypoglycemic Activity Of Ginseng Aqueous Extract

Diabetes Mellitus is the glucose, protein and lipid metabolic disorder syndrome caused by absolute or relative lack of insulin secretion, the basic characteristics of which is blood glucose increasing. Currently, diabetes has become globally prevalent disease, and is the third disease causing death following cancer and cardiovascular disease. Therefore, it is very important to look for a safe and effective method to control blood sugar for diabetes prevention and treatment.Panax ginseng C. A. Meyer (ginseng) has been recorded to treat "Xiaoke" symptom in many ancient Chinese medical literatures. "Xiaoke", in general, indicates diabetes mellitus. Ginseng polysaccharide is one of the active ingredients of ginseng. Some studies have shown that ginseng polysaccharides can decrease the blood sugar of diabetes mice after intraperitoneal injection. However, since the ginseng polysaccahrides fractions have various differences such as moleculaer weight and sugar composition, they showed different effects on insulin-sensitivity and regulation of glucose metabolism. Existing studies showed that hypoglycemic ginseng polysaccharides usually administe with intraperitoneal injection. In order to further facilitate administion, we selected oral administion to find the best hypoglycemic fraction of ginseng polysaccharides. In this paper, the hypoglycemic effect of ginseng aqueous extract, polysaccharides, and pectin were studied, respectively. The mechanisms of ginseng pectin were investigated. The results are as followings:1. Ginseng aqueous extract, mainly containing gingenosides and polysaccharides, produced dose-dependent hypoglycemic effect. With the increasing of doses in oral, ginseng aqueous extract can reduce blood sugar of normal mice and promote the glucose transforming into triglycerides. Also, ginseng aqueous extract can significantly improved glucose tolerance in normal mice. In addition, it can significantly reduce the blood glucose levels in alloxan-induced hyperglycemic mice. In summary, Ginseng aqueous extract played an important role in the regulation of glucose and lipid metabolism, prevention of metabolic syndrome in normal mice and protection of the islet cells in diabetic mice.2. The blood glucose levels in mice with streptozotocin-induced diabetes were reduced significantly by oral administration of Ginseng polysaccharides. The blood glucose after treatment decreased with the dose increasing from 12.5 mg/kg/d, and reached the most significant hypoglycemic effect with the rate of 28.52% (p <0.05) at the dose of 50 mg/kg/d. The study indicated that 50 mg/kg/d of ginseng polysaccharide was the best dose for hypoglycemic effect in diabetic mice.3. Ginseng polysaccharides were composed of gensing neutral polysaccharides and acidic pectin, which played different roles on hypoglycemic action with different routes of administration. 50 mg/kg/d ginseng polysaccharides can significantly reduce the high blood glucose levels of diabetic mice, its hypoglycemic rate was 28.52% (p <0.05). 10 mg/kg/d ginseng acidic polysaccharide isolated from ginseng polysaccharide significantly reduced the high blood glucose levels, and the hypoglycemic rate was 35.59% (p <0.01), reached normal level. This indicated the main hypoglycemic component of ginseng polysaccharides was acidic polysaccharide fraction when administered by oral. 30 mg/kg/d ginseng polysaccharide administered by intraperitoneal injection significantly reduced the blood glucose levels of STZ-induced hyperglycemia, the hypoglycemic rate was 71.67% (p <0.01). 6 mg/kg/d neutral polysaccharide isolated from Ginseng polysaccharide significantly reduced the high blood glucose values in mice with the hypoglycemic rate of 78.75% (p <0.01). These results indicated that the neutral polysaccharide fraction was the main component of ginseng polysaccharides with hypoglycemic activity when injected through intraperitoneal. Maybe, Genseng acidic pectin polysaccharides can inhibit the activity of glycosidase in the gastrointestinal tract.4. Hypoglycemic mechanism of ginseng pectin. Give ginseng pectin by oral, the blood glucose in normal mice showed no significant difference. The hypoglycemic activity of ginseng pectin reached the highest hypoglycemic effect at the dose of 50 mg/kg/d. The blood and plasma insulin levels of STZ-mice increased significantly. At the same time, the results showed that ginseng pectin can significantly increase the plasma insulin, SOD, liver glycogen level, and reduce the concentration of MDA. The reduced hypoglycemic effect of the Ginseng neutral polysaccharide may be caused by the digestion in gastrointestinal tract or other complex reasons. In vitro, tests showed that Ginseng pectin had significantly inhibitory effect againstα-glycosidase. Based on above results we can infer the hypoglycemic mechanism of ginseng polysaccharide may be performed by various factors.5. The crude enzymes of rat intestinal were obtained and used to hydrolyze Ginseng pectin in vitro. The results showed that the WGPA-2-AG with type-I rhamnogalacturonan (RG-I) domains was hydrolyzed after 16 h incubation, one oligosaccharide fraction with the molecular weight of 1×103 Da was obtained. The monosaccharide components of the hydrolysis product were mainly Ara and Gal, these two components account for 78.2% in sugar content. The oligosaccharide obtained was a RG-I configuration fragments. WGPA-4-HG with homogalacturonan (HG) domains was not hydrolyzed after 16 h reaction, which sugar content was not changed. We infer that the structure of WGPA-4-HG is relatively stable, thus it is difficult to hydrolyze it in the digestive tract.In conclusion, the hypoglycemic studies showed that ginseng aqueous extract can regulate glucose and lipid metabolism in normal mice, increase postprandial blood glucose, protect the islet cells of diabetes mice, and so on. Ginseng pectin showed significant hypoglycemic effect by oral administration. Ginseng pectin increased plasma insulin and liver glycogen level to regulate glucose metabolism, promoted antioxidant and inhibited free radical-induced lipid peroxidation to protect islet cells, and inhibited theα-glucosidase activity in vitro to decrease absorption of glucose. Ginseng pectin with RG-I domain can be in vitro digested by intestinal hydrolyase to give an oligosaccharide fraction with RG-I domain. In animal digestive tract, ginseng pectin would be hydrolyzed to oligosaccharides or other small molecules by various enzymes and intestinal microbial fermentation. These hydrolysis products may cause various hypoglycemic effects of ginseng polysaccharides.