Hypoglycaemic and anti-hyperglycaemic activity of aqueous extract of Azanza garckeana leaves in normal and alloxan -induced diabetic rats

Abstract

The aqueous extract of Azanza garckeana (AG) leaves was tested for hypoglycaemic and anti-hyperglycaemic activities. The extract was administered to Wistar rats orally at 100 and 150 mg/kg doses in oral glucose tolerance test (OGTT), glucose baseline conditions and diabetic conditions. OGTT was tested with the administration of the aqueous extract to normal rats and blood glucose levels were measured for each animal at 30, 60 and 120 minutes after glucose loading. For the hypoglycaemic activity, the extract was administered to normal rats and blood glucose levels were measured for each animal, at 30, 60 and 120 minutes. Alloxan induced diabetic rats were used to determine the anti-hyperglycaemic activity. The extract was administered for 14 days and blood glucose levels were measured for each animal at a weekly interval for 2 weeks. The OGTT study in normal rats showed that administration of the extract at 150 mg/kg reduced blood glucose levels within 30 to 60 minutes after glucose administration, as was also observed with the standard drug (glibenclamide). For the hypoglycaemic study, fasting blood glucose test in normal rats showed that aqueous extract of AG leaf at 150 mg/kg, produced significant (P < 0.05) blood glucose reduction at 60 minutes after administration while glibenclamide revealed significant reduction throughout the time as compared with normal control. 150 mg/kg was the most effective dose during the anti-hyperglycaemic study as it had a significant reduction in blood glucose levels after the 7th day. However glibenclamide had a more significant reduction when compared with treated groups. In conclusion, these results clearly indicate that aqueous leaf extract of Azanza garckeana possess hypoglycaemic and anti-hyperglycaemic effects in normal and diabetic rats and thus support its traditional use to treat diabetes. Therefore, a detailed mechanism-based study and isolation of bioactive compounds responsible for the observed activities of Azanza garckeana is recommended.