Hypoglycaemic and anti-hyperglycaemic activity of Tabernanthe iboga aqueous extract in fructose-fed Streptozotocin type 2 diabetic rats
Bourobou Bourobou, Henri-Paul
Root bark preparations of the Gabonese plant Tabernanthe iboga (T. iboga) has long been used in traditional medicine in Central and West African regions for the management of type 2 diabetes (T2D). This study is the first investigation of in vivo hypoglycaemic activity in healthy rats and anti-hyperglycaemic activity of T. iboga in a 10% fructose-fed (40 mg/kg i.p.) streptozotocin (STZ) injected type 2 diabetic rat model. T. iboga at 50 to 200 mg/kg induced hypoglycaemia activity over 3 h fasted glucose tolerance in healthy Wistar rats and anti-hyperglycaemic effects on non-fasted and fasted blood glucose in fructose-fed STZ T2D rats with no toxicity. Fructose-fed STZ T2D rats developed characteristic type 2 diabetic complications over 6 weeks exhibiting significantly elevated fasting and non-fasting blood glucose, polydipsia, reduced body weight gain and glucose and insulin tolerance compared with STZ alone and normal control rats. T. iboga (50 mg/kg and 200 mg/kg bw) administered p.o. once daily for 4 weeks significantly improved diabetic symptoms of polydipsia, reduced body weight, hyperglycaemia, glucose and insulin tolerance (as AUC) compared with fructose-fed STZ T2D rats. T. iboga aqueous extract (50 mg/kg and 200 mg/kg) also significantly reversed altered actions of marker enzymes of liver including alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate transaminase (AST), creatinine, HbA1c and elevated triglycerides in fructose-fed STZ type 2 diabetic rats. Our outcomes show that daily oral provision of T. iboga improves type 2 diabetes complications, superior to glibenclamide, in rat fructose-fed STZ model and offers the potential for safe clinical management of T2D in Gabon.