Anti–diabetic activity of the semi–purified fractions of Averrhoa bilimbi in high fat diet fed–streptozotocin–induced diabetic rats

The present study was designed to investigate the hypoglycemic and hypolipidemic activities of the semi–purified fractions of an ethanolic leaf extract of Averrhoa bilimbi (ABe) in high fat diet (HFD)–streptozotocin (STZ)–induced diabetic rats. Male Sprague–Dawley rats aged 10 weeks (200–250 g) were fed with a high fat diet obtained from Glen Forrest stock feeders (Western Australia) for 2 weeks prior to intraperitoneal injection with streptozotocin (STZ, 50 mg/kg). The leaves of A.bilimbi were exhaustively extracted with 80% ethanol, concentrated at 40°C using a rotavapor and partitioned successively with butanol, ethylacetate and hexane to get aqueous (AF), butanol (BuF), ethylacetate (EF), and hexane fractions (HF). The fractions were freeze–dried to obtain powders of each. To investigate the effect of long term administration of the hypoglycemic fractions, diabetic animals were treated with vehicle (distilled water), AF (125 mg/kg), or BuF (125 mg/kg), twice a day for 14 days. The long term administration of AF and BuF at a dose of 125 mg/kg significantly (P < 0.05) lowered blood glucose and triglyceride concentrations when compared to the vehicle. The hepatic glycogen content was significantly higher (P < 0.05) in AF–treated rats when compared to diabetic control, however no change was found in the BuF–treated rats. Moreover, AF as well as BuF did not cause any significant change in the total cholesterol and HDL–cholesterol. There was also no difference in liver thiobarbituric acid reactive substances (TBARS) and cytochrome P450 values between AF, BuF and vehicle–treated control rats. In conclusion, the results indicate that AF is more potent than BuF in the amelioration of hyperglycemia and hyperlipidemia in HFD fed–STZ diabetic rats. Hence, AF is a potential source for the isolation of active principle (s) for oral anti–diabetic therapy.