Long-term anti-diabetic and anti-hyperlipidaemic effects of aqueous stem bark extracts of Irvingia gabonensis in streptozotocin-induced diabetic rats

Abstract

Our previous studies have shown that aqueous stem bark extracts of Irvingia gabonensis possess long term hypoglycaemic effects in normal rabbits. This study was designed to evaluate the long-term anti-diabetic and anti-hyperlipidaemic effects of aqueous stem bark extracts of I. gabonensis in streptozotocin-induced diabetic rats. Twenty four Wistar rats in three groups, normal control, diabetic control and I. gabonensis treated diabetic rats (TDR) were used for this study. Diabetes was induced in 16 rats by intraperitoneal injection of streptozotocin (STZ) at 65 mg/kg body weight. Upon confirmation of diabetes, the treated diabetic rats were orally (by gavage) given aqueous extracts of I. gabonensis bark at 200 mg/kg body weight daily for 24 weeks. Body weight was monitored weekly, while fasting blood sugar (FBS) and serum lipid profile (triglycerides, total cholesterol, LDL-cholesterol and HDL-cholesterol) were assessed at specific intervals for 24 weeks. I. gabonensis reduced the FBS of the treated diabetic rats to normal control levels 2 weeks after the commencement of treatment. The reduction of FBS was sustained till the end of the study (24 weeks). Furthermore, at various stages of monitoring, the extract reduced the STZ-induced elevation of serum triglycerides, total cholesterol and LDL-cholesterol, and significantly (p < 0.05) increased the STZ-induced decrease in HDL-cholesterol. Our study concludes that aqueous stem bark extracts of I. gabonensis possess profound long-term anti-diabetic and hypolipidaemic effects. These anti-hyperlipidaemic effects as well as the presence of phytochemicals with recognizable anti-oxidant effects will be useful in the treatment of diabetic complications.