Hypoglycemic Potential of Polysaccharides of the Leaf Extract of Telfairia occidentalis

Abstract

Context: Telfairia occidentalis Hook (Cucurbitaceae), a popular vegetable in West Africa, has been reported to have antidiabetic property. But the active components are not yet known. Aims: This study was carried out to determine the hypoglycemic potentials and the antidiabetic property of polysaccharides of the leaf of Telfairia occidentalis. Place and Duration of Study: Hypertension and Cardiovascular Physiology Research Laboratory; School of Pharmaceutical Sciences, University Sains Malaysia, Penang, Malaysia, between June 2013 and October 2013. Methodology: The dried plant material was macerated with water and extracted with ethyl acetate to obtain ethyl acetate and aqueous residue fractions. To obtain the crude polysaccharides, the plant material was boiled with water. Ethanol (96%) was added to the extract. The precipitate obtained was successively washed with ethanol (99%), ether and acetone. Crude proteins were obtained by ammonium sulphate precipitation. The various fractions (250 and 500mg/kg) were orally administered to normoglycemic and STZ-induced diabetic rats. Blood glucose was evaluated with a glucometer at 0, 1, 2 and 4 hours, after administration. Glibenclamide (4mg/kg) was used as the positive control. Column chromatography and HPLC analyses of the aqueous residue and crude polysaccharides were carried out. Results: None of the fractions at the two dose levels affected blood glucose concentration of the normoglycemic rats. However, the aqueous residue and crude polysaccharides significantly (p=0.05) reduced glucose level at 4 hours in the diabetic rats from 100% at 0 hour to 74.28 and 60.87% at 4 hours, respectively. Based on the column chromatography and HPLC profiles, the hypoglycemic activity of the aqueous residue and crude polysaccharides fractions could be attributed to their carbohydrates content. Conclusion: Polysaccharides from the leaf of Telfairia occidentalis possess hypoglycemic activity and have the potential of being useful in the management of diabetes. Further work needs to be done to characterize the active polysaccharides.