Ginsenoside Rh2 is One of the Active Principles of Panax Ginseng Root to Improve Insulin Sensitivity in Fructose-rich Chow-fed Rats

Abstract

Ginsenoside Rh2, one of the ginsenosides contained in the Panax ginseng root, was employed to screen the effect on insulin resistance of rats induced by a diet containing 60% fructose. Single intravenous injection of ginsenoside Rh2 decreased the plasma glucose concentrations in 60 minutes in a dose-dependent manner from 0.1 mg/kg to 1 mg/kg in rats with insulin resistance induced by fructose-rich chow. Repeated intravenous injection of ginsenoside Rh2 (1 mg/kg per injection, 3 times daily) into rats which received fructose-rich chow for 3 consecutive days decreased the value of glucose-insulin index, the product of the areas under the curve of glucose and insulin during the intraperitoneal (i.p.) glucose tolerance test. This means that ginsenoside Rh2 has an ability to improve insulin action on glucose disposal. The plasma glucose lowering action of tolbutamide, induced by the secretion of endogenous insulin, is widely used to characterize the formation of insulin resistance. Time for the loss of plasma glucose lowering response to tolbutamide (10 mg/kg, i.p.) in rats during insulin resistance induction by fructose-rich chow was also markedly delayed by the repeated treatment of ginsenoside Rh2, as compared to the vehicle-treated control. Thus, the repeated treatment of ginsenoside Rh2 delayed the development of insulin resistance in high fructose feeding rats. Increase of insulin sensitivity by ginsenoside Rh2 was further identified using the plasma glucose lowering action of exogenous insulin in streptozotocin-induced diabetic rats (STZ-diabetic rats). Repeated injection of ginsenoside Rh2 at the same dosing (1 mg/kg, 3 times daily) into STZ-diabetic rats for 10 days made an increase of the responses to exogenous insulin. Taken together, it can be concluded that ginsenoside Rh2 has an ability to improve insulin sensitivity and it seems suitable to use ginsenoside Rh2 as an adjuvant for diabetic patients and/or the subjects wishing to increase insulin sensitivity.

Isolation, Synthesis and Structures of Cytotoxic Ginsenoside Derivatives

“…Ginseng (Panax ginseng C. A. Meyer) has been used in China for thousands of years as a traditional medicine and proven to possess a wide range of pharmacological properties, such as anti-fatigue, memory stimulating and anti-diabetes, as well as in the prevention of cancer and the ageing process [1][2][3][4][5][6][7]. Recent publications also indicated some rare ginsenosides such as Rh 2 , Rg 3 and M 1 showed significant in vivo anti-tumor activities [8][9][10][11][12].…”

Merit of Ginseng in the Improvement of Insulin Resistance

“…Thus, ginsenoside Rh2 is valued as the bioactive principle in the glucose homeostasis. In our study, Rh2 has the ability to improve insulin resistance in a dose-dependent fashion [25]. The fasting plasma level of glucose was significantly higher in rats fed with 4 weeks fructoserich chow than that fed with standard chow for same period.…”

“…Even at the end of treatment, tolbutamide could effectively decrease the plasma glucose in rats receiving fructose-rich chow combined treatment with ginsenoside Rh2, the plasma glucose lowering activity of tolbutamide remained significant. Also, the glucoseinsulin index in rats received fructose-rich chow was reduced by same 3 days treatment of ginsenoside Rh2 [25]. Improvement of insulin resistance by ginsenoside Rh2 has thus been identified.…”

“…We treated Rh2 through injection into animal is going to rule out the pharmacokinetic parameters. Following the 3 days of ginsenoside Rh2 treatment (1 mg/kg per intravenous injection, 3 injections per day), plasma glucose levels in rats with insulin resistance fell to the value significantly lower than the vehicle-treated counterparts [25].…”

“…The fasting plasma level of glucose was significantly higher in rats fed with 4 weeks fructoserich chow than that fed with standard chow for same period. A dose-dependent reduction of plasma glucose was obtained in fructose-rich chow-fed rats receiving an in-travenous injection of ginsenoside Rh2 from 0.1 mg/kg to 1 mg/kg [25]. We treated Rh2 through injection into animal is going to rule out the pharmacokinetic parameters.…”