Abstract

EFFECTS OF THE AQUEOUS EXTRACT OF ALSTONIA BOONEI (APOCYNACEAE) BARKS ON SUCROSE-INDUCED GLUCOSE INTOLERANCE AND INSULIN RESISTANCE IN WISTAR RATS

Ngueguim Tsofack Florence, Nyawa Kengne Steve Landry, Dzeufiet Djomeni Paul Desire, Kamtchouing Pierre and Dimo Theophile*

ABSTRACT

The aqueous extract of Alstonia boonei (A. boonei) has been shown to have antidiabetic activity using chemical drug. However there is no report on its effect on sucrose-induced insulin resistance and glucose tolerance in long term consumption. The current study investigates the effects of A. boonei aqueous extract on sucrose-induced glucose intolerance and insulin resistance in rats. Animals were fed with 20% sucrose solution and 5% sucrose in drinking water during ten weeks. Those with glucose tolerance abnormality were treated with the extract (100 or 200 mg/kg) for two more weeks after stopping or without stopping the sucrose. Animals were subjected to insulin sensitivity and glucose tolerance tests. Sera and homogenates of organs were used for biochemical analysis. Sucrose administration caused hyperglycemia (54.85%), glucose intolerance but failed to induce insulin resistance. Rats receiving sucrose for two more weeks showed hyperglycemia (71.39%), glucose intolerance and insulin resistance. When stopping sucrose, the extract significantly reduced blood glucose and improved sucrose tolerance. The extract significantly decreased blood glucose, prevented insulin tolerance and insulin resistance. Sucrose caused a significant increase in cholesterol, triglycerides, LDL-cholesterol, atherogenic index, ALT, AST, creatinine, MDA levels and a decrease of GSH concentration and SOD activity. The extract significantly improved the concentrations of all these parameters. The aqueous extract of A. boonei improves glucose tolerance and insulin sensitivity due to its hypoglycemic, hypolipidemic and antioxidant activities. It can be used to manage glucose intolerance and insulin resistance in diabetic patients.

Keywords: Sucrose, glucose tolerance, insulin resistance, Alstonia boonei.