Anti-hyperglycemic Activity of Four Plants Extracts Effective against Alpha Glucosidase in Normal and Diabetic Rats

Postprandial hyperglycemia results in the development of chronic complications. Therefore, its control is critical in the treatment of diabetes. One of the main therapeutic approaches for reducing postprandial hyperglycemia is to reduce the absorption of carbohydrates by enzyme inhibitors such as Acarbose which have already been clinically used as a medicine for diabetic patients. Aqueous and methanolic extracts of Zataria multiflora, Pistachio hulls, Myrtle leaves and Quercus infectoria which had inhibited alpha glucosidase (>90%) in our previous study were prepared by maceration method. Male wistar rats were divided into two, streptozotocin-induced diabetic group and non-diabetic group. Then each group subdivided into 6 groups of control receiving 2g/kg maltose, positive control receiving 2g/kg maltose as well as Acarbose and 4 other groups receiving 2g/kg maltose and one of the prepared extracts (1000mg/kg) after deprivation of food. Blood glucose level was measured before and 30, 60 and 120 min. after extract administration. In non-diabetic rats, Quercus infectoria and Myrtle extracts significantly reduced the postprandial glucose levels (60 and 50% respectively, P<0.0001) comparing to the control. The effect of Pistachio extract on reduction of blood glucose was not significant. Zataria multiflora extract had no significant effect (P>0.05) but showed a reveres effect on plasma glucose and remained at high level up to 60 minutes. Further studies must be done for proving the efficacy of Zataria multiflora and Quercus infectoria for hyperglycemic patients with uncontrolled diets