Antihyperglycaemic and anti-oxidant properties of Anoectochilus formosanus in diabetic rats.

1. In the present study, we investigated aqueous extracts of Anoectochilus formosanus (AFE) for antihyperglycaemic and anti-oxidant effects in diabetic rats induced by streptozotocin (STZ). 2. Diabetic rats were randomly divided into groups and treated orally by gavage with vehicle (distilled water) or AFE (1 and 2 g/kg), once a day for 21 days. 3. At the end of the 21 day period, AFE (2 g/kg) significantly reduced fasting blood glucose, serum fructosamine, triglycerides and total cholesterol compared with vehicle-treated diabetic rats. In vehicle-treated diabetic rats, levels of renal lipid peroxidation were increased, whereas glutathione concentrations were not affected. Renal lipid peroxidation levels were significantly lower and renal reduced glutathione (GSH) concentrations were significantly higher in AFE-treated diabetic rats compared with vehicle-treated diabetic rats. The diabetic kidney in the vehicle-treated group showed a decrease in catalase, but the activity of glutathione peroxidase (GSH-Px) was increased. 4. The activity of catalase, but not GSH-Px, was significantly reversed by AFE treatment. These results indicate that AFE (1 and 2 g/kg) not only possesses an antihyperglycemic effect, but that it may also reduce oxidative stress in diabetic rats.