Chromatographic and anti-diabetic studies on root extract of acanthus montanus (acanthaceae)

The roots of Acanthus montanus were extracted with methanol and the extract successively extracted with n-hexane, petroleum ether, ethylacetate, diethylether and chloroform to investigate the anti-diabetic activity based on ethnomedicinal lead. Through a pilot study the ethylacetate fraction (EAF) was studied against alloxan-induced diabetic rats. Preliminary phytochemical analysis and acute toxicity studies were carried out in mice intraperitoneally. An attempt was made to resolve the EAF into its components using thin layer chromatography (TLC). Result of the anti-diabetic study shows significant dose-dependent reduction (P <0.05) in blood sugar levels of both normoglycemic and hyperglycemic rats. When doses of 100, 200 and 300 mg/kg of the EAF were administered intraperitoneally to alloxan-induced diabetic rats, significant decrease in blood sugar level occurred (21.91, 38.12 and 49.20 % respectively) compared to the sugar lowering effect of glibenclamide (51.78 %). In normal rats, EAF (100, 200 and 300 mg/kg) exhibited a significant reduction of the blood sugar level of 19.20, 27.80 and 40.74 % respectively, while glibenclamide caused a 49.94 % reduction. Phytochemical tests showed the presence of alkaloids, flavonoids, glycosides, steroids, saponins, tannins and terpenoids. Acute toxicity test carried out in mice using Lorke’s methods showed that the extract was safe, since no death was recorded at a dose of 5000 mg/kg. The study shows that the extract of the EAF of Acanthus montanus possessed a significant and dose-dependent hypoglycemic activity in normoglycemic and alloxan-induced diabetic rats and provides a pharmacological basis for the use of Acanthus montanus root in folk medicine in management of diabetes. Among the chromatographic solvent systems tested, chloroform: ethylacetate (6:4) gave the best resolution of the EAF giving the highest number of spots. The result of the chromatographic studies can be a guide for further studies to isolate and characterize the active principle(s) responsible for this activity.