Black ginseng was produced by a repeated steaming and drying process, subsequent extraction with 70% ethanol, filtration, and lyophilization. The effect of GBG05-FF on glucose uptake and related protein expression and phosphorylation were determined in C2C12 cells. Furthermore, we evaluated the anti-diabetic effects of GBG05-FF in STZ-induced diabetic mice.
GBG05-FF significantly (p<0.05) increased glucose uptake in C2C12 myotubes via AMPK, Sirt1 and PI3-K pathway. In addition, GBG05-FF improved the fasting blood glucose levels and glucose tolerance in STZ-induced diabetic mice. GBG05-FF decreased blood parameters such as glycated hemoglobin, triglyceride and total cholesterol. Quantitative RT-PCR assay revealed that in the STZ-induced diabetic mice treated with GBG05-FF, the expression of hepatic genes involved in gluconeogenesis (phosphoenolpyruvate carboxykinase (PEPCK), glucose 6-phosphatase (G6Pase)), glycogenolysis (liver glycogen phosphorylase (LGP)) and glycogenesis (glycogen synthase (GS)) was suppressed, while the expression of the genes involved in glucose uptake (glucose transporter (GLUT) 1, GLUT4) and β-oxidation (acyl-CoA oxidase (ACO), carnitine palmitoyl transferase 1a (CPT1a), mitochondrial medium chain acyl-CoA dehydrogenase (MCAD)) in muscle were increased. GBG05-FF delayed diabetes-associated muscle atrophy by activating mTOR. The major bioactive compounds including ginsenoside Rg1, Rg3(S), Rg3(R), Rg5, Rk1 and Rh4 were evaluated for glucose uptake effect in C2C12 myotubes; the data indicated that Rh4 significantly (p<0.05) increased glucose uptake.
Collectively, the results suggested that GBG05-FF is a potentially useful agent for treatment of diabetes by increasing glucose uptake.