Hypoglycaemic and hypolipidaemic effects of crude extracts and chromatographic fractions of Morinda morindoides root bark in diabetic rats

Hypoglycaemic and hypolipidaemic effects of different extracts and fractions of root bark from the plant Morinda morindoides (Baker) Milne-Redh of the family Rubiaceae were evaluated in alloxan-induced diabetic rats. The aqueous and methanolic extracts were administered to 48 rats orally at a dose of 400 mg.kg(-1) for 21 days. Fractions (hydromethanol, hexane, chloroform and ethyl acetate) from bio-activity guided fractionation and chromatographic sub fractions (CsF) A-F from accelerated gradient chromatography were also evaluated in 45 rats for the hypoglycaemic activity at doses of 400 mg.kg(-1), 200 mg.kg(-1) and 100 mg.kg(-1) of solvent fractions and (CsF) A-F, respectively. Glibenclamide was used as positive control. Polyoxyethylene sorbitan monooleate and distilled water administered to rats were used as negative controls. The dose of 400 mg.kg(-1) of aqueous and methanolic extracts and 100 mg.kg(-1) of chloroform CsF B of Morinda morindoides caused (62.8%, 56% and 74%, respectively) reductions in blood glucose level (BGL). The aqueous extract caused significant (P < 0.05) decreases in the values of serum cholesterol (133.48 +/- 1.1) mg.dl(-1), low density lipoprotein (66.38 +/- 2.5) mg.dl(-1) and significant (P < 0.05) increase in the value of high density lipoprotein (51.03 +/- 3.0) mg.dl(-1) when compared to the control. These results confirm the folkloric claim of the hypoglycaemic and hypolipidaemic activities of Morinda morindoides root bark.