Antidiabetic Activities of Methanolic Extracts of Marrubium vulgare Leaves in Rats

This study was carried out to evaluate the chronic effect and possible mechanism of action of the methnolic extract (MEex) of Marrubium vulgare using normal and streptozotocin-induced diabetic rats, and in vitro methods. Administration of the MEex at a dose of 200 mg/kg daily on diabetic rats for 5 weeks showed a significant lowering (p < 0.05) of the blood glucose level, serum urea, uric acid and creatinine and correction of the lipid profiles compared to diabetic rats. However, MEex significantly increased (p < 0.05) the glucose uptake by liver and skeletal muscle. The increase in glucose uptake was also shown when the liver and skeletal muscle was treated by 5mg/kg of glibenclamide. Furthermore, the effect of this extract on glucose absorption in the everted rat jejunum showed that MEex at concentrations of 2 mg/mL and 5 mg/mL significantly reduced the glucose absorption of the jejunum (p < 0.05). Similarly, the absorption of glucose was also inhibited by 1 mg/mL of acarbose (p < 0.01). These results suggest that the effect of MEex may be due to extrapancreatic mechanisms. This antidiabetic activity is, at least partly, due to modulation of glycogen synthesis and inhibition of intestinal glucose absorption.