Hypoglycemic activity of aqueous seed extract of Hunteria umbellata in normal and streptozotocin-induced diabetic rats

The present study evaluated the aqueous seed extract of Hunteria umbellata K. Schum (Apocynaceae) for hypoglycemic activity in rats. Diabetes was induced by a single dose of streptozotocin (50mg/kg i.p.). Daily doses of 400, 800, and 1000mg/kg of extract were orally administered to fasted normal and diabetic rats. Blood glucose levels were monitored after 0, 2, 4, 8, 12h and on day 14 post treatment. Liver glycogen levels were also estimated on day 14. In normal rats, only 400mg/kg of the extract produced a significant reduction in blood glucose at the 4h (P<0.05) which was 22.15±4.88%. In diabetic rats, the extract, 400, 800mg/kg, caused significant reduction (P<0.01), 51.87% ± 5.79% and 43.47% ± 8.06% respectively, with maximum effect at 8h. This reduction in blood glucose was greater than that of glibenclamide (31.03% ± 8.86%). Diabetic rats administered with 400mg/kg extract produced a significant reduction (P<0.01) on day 14 (43.60% ± 8.10%). Liver glycogen levels were significantly increased (P<0.05) in diabetic rats administered with doses of 400 and 800mg/kg extracts and these were comparable to glibenclamide. Acute toxicity data showed no mortality in mice up to 17.5g/kg. We conclude that the extract possesses marked hypoglycemic effects in diabetic rats possibly through increased glycogenesis, thus justifying its use in herbal medicine for the treatment of diabetes. © 2009 Informa UK Ltd.