Antidiabetic effects of knema glauca leaf extract toward inhibitions of a-amylase and a-glucosidase assays

Abstract

This study was part of our preliminary work in the search for biologically active compounds from endemic plants of Kuala Keniam National Park, Pahang, Malaysia. Postprandial hyperglycaemia is linked to the development of diabetes complications such as micro and macro vascular diseases. Inhibitions of carbohydrate digestive key enzymes, a-amylase and a-glucosidase using plant extracts are possible therapeutic strategies to suppress postprandial hyperglycaemia. The aim of this study was to investigate the effects of the dichloromethane leaf extract of Knema glauca (DLKG) in vitro and in vivo a-amylase and a-glucosidase inhibitory activities. The antidiabetic property of DLKG was investigated by using in vitro a-amylase and a-glucosidase inhibitory activity assays. The effects of DLKG on oral starch and sucrose challenge tests were investigated by administering 125, 250 and 500 mg/kg of the extract to normal and diabetic rats. DLKG demonstrated potent a-amylase and a-glucosidase inhibitory activities with IC50 values of 1.26 and 4.09 μg/ml, respectively. In the oral starch challenge test, the extract significantly (p<0.05) reduced blood glucose levels in both normal and diabetic rats. On the other hand, DLKG showed significant (p<0.05) reduction of blood glucose levels in normal rats in the oral sucrose challenge test. The results showed that the leaves of K. glauca possessed a beneficial effect in reducing postprandial hyperglycaemia and have potential as an alternative antidiabetic agent.