| American ginseng (Panax quinquefolius L.), which belongs to Araliaceae, is native to east U.S., Montreal and Quebec of Canada, and France. Recently, it is also cultivated in northeast China and Beijing, Xian, Jiangxi and Shandong. American ginseng has been used in China for more than 200 years, and is famous for the activity of reinforcing Qi, yin-nourishing, heat-clearing and produce saliva. Ginsenosides are the primary bioactive components of American ginseng. The content of ginsenosides in American ginseng leaf is higher than that in main-root and root-hair, and the content of PPD (Protopanaxadiol) is higher than PPT (Protopanaxatriol) in American ginseng leaf. Therefore, the development and utilization of American ginseng leaf is essential. Making rational use of American ginseng leaf can decrease the waste of resources. The bioactive activity of ginsenosides in American ginseng leaf contains anti-aging, enhancing immunity, promoting hematopoiesis, protecting focal cerebral ischemia damage, anti-myocardial ischemia, decreasing blood glucose and improving glucose tolerance. PPD from American ginseng leaf has the activity of regulating blood lipid.Ginsenoside Rb3 is one of the main components of PPD in American ginseng leaf. Most literature reports studies on the effect of ginsenoside Rb3 on cerebrovascular disease, such as protecting nervous system and protecting ischemic injury in brain, antithrombotic activity and affecting against myocardial injury. However, there is little report about ginsenoside Rb3 in controlling blood glucose and adjusting blood lipid. In order to provide some theoretical basis for studies on the application of monomeric ginsenoside in metabolic disease, such as diabetes and dyslipidemia, the present study was designed to investigate the effect of ginsenoside Rb3 on alloxan-induced diabetic mice and high diet induced dyslipidemic mice.PPD and PPT were isolated from the extract of American ginseng leaf and stem by macroporous resin NKA-12. PPT was washed down by 30% ethanol and PPD was washed down by 50% ethanol. The weight of PPT and PPD were 42.5 g and 111.2 g, respectively. Ginsenoside Rb3 was isolated and purified from PPD by silica gel column chromatography using two solvent system:chloroform-methanol-water (65:35:10) and N-butanol-acetidin-water (4:1:5). After repeat separation and purification,10.5 g ginsenoside Rb3 was obtained, and the yield was 5.25%. Further analysis by HPLC showed that the purity of ginsenoside Rb3 was 93.87%.This paper investigated the effect of ginsenoside Rb3 on alloxan-induced diabetic mice. The results showed that ginsenoside Rb3 reduced fasting blood glucose level, food intake, water intake, improved oral glucose tolerance, and repaired injured pancreas tissues of alloxan-induced diabetic mice. These demonstrated that ginsenoside Rb3 has anti-diabetic activity. Therefore, it was suggested that ginsenoside Rb3 possesses the potential of the clinical use in improving the symptoms of diabetes and preventing cardiovascular disease resulted from hyperglycemia and impaired glucose tolerance. Glucose consumption in C2C12 myotubes was also determined in vitro. At concentrations of 100 and 200μM, ginsenoside Rb3 increased glucose consumption in C2C12 myotubes as compared to the control group. However, the influence of ginsenoside Rb3 on C2C12 myotubes was much lower than that of insulin at 100 nM. The result shows that ginsenoside Rb3 has the activity of increasing glucose consumption in C2C12 myotubes. Therefore, it was suggested that ginsenoside Rb3 possesses the application value of increasing insulin sensitivity.In order to investigate the effect of ginsenoside Rb3 on TC (total cholesterol), TG (total triglycerides), LDL-C (low density lipoprotein-cholesterol), HDL-C (high density lipoprotein-cholesterol), LDL-C/HDL-C and oral glucose tolerance in experimental dyslipidemic mice, dyslipidemic mice was induced by high fat diet. Ginsenoside Rb3 significantly reduced TC, TG, LDL-C and the ratio of LDL-C/HDL-C, and reduced AUC of dyslipidemic mice in OGTT. These results suggest that ginsenoside Rb3 can regulate lipid metabolism, and improve glucose tolerance of experimental dyslipidemic mice. These results provide the theoretic basis for the application of ginsenoside Rb3 in preventing and treating AS, CHD (coronary heart disease) and hypertension resulted from dyslipidemia. |
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