Hypoglycemic effects of the aqueous seed extract of Hunteria umbellata in normoglycemic and glucose and nicotine induced hyperglycemic rats
The dry seeds of Hunteria umbellata K. Schum (Apocynaceae) are highly valued in African traditional medicine in the treatment of various human diseases, including diabetes mellitus and obesity. In the present study, the hypoglycemic and weight loss effects of 50–200mg/kg of the aqueous seed extract of Hunteria umbellata were investigated in normoglycemic and glucose- and nicotine-induced hyperglycemic rats. In addition, examination of the acute oral toxicity using the preliminary and the main tests of the Up-and-Down Procedure according to OECD/OCDE Test Guidelines on Acute Oral Toxicity was conducted . Phytochemical analysis of the aqueous seed extract was also carried out using standard procedures [2, 3]. Results showed that the extract caused progressive and significant (p<0.05, p<0.01, and p<0.001) dose-related reduction in the blood glucose concentrations in normal and drug-induced hyperglycemic rat models, an effect, which was more than that of glibenclamide and mediated via inhibition of intestinal glucose uptake and adrenergic homeostatic mechanisms. The extract also caused significant (p<0.05, p<0.01, and p<0.001) dose-dependent reduction in the average body weight of treated rats when compared to untreated rats. The acute oral toxicity showed that the extract had an LD50 of 1020mg/kg and as such can be considered slightly toxic. Results of the phytochemical analysis of the seed extract revealed the presence of alkaloids, flavonoids, tannins and glycosides. Thus, the data generated in the present study has a strong positive correlation with its folkloric use in the treatment of suspected type 2 diabetic patients, although it should be used with great caution.
References:1. Acute Oral Toxicity (OECD Test Guideline 425) (2001). Statistical Programme (AOT425StatPgm), Version 1.0. http://www.oecd.org/oecd/pages/home/displaygeneral/0,3380,EN-document-524-nodirectorate-no-24–6775–8,FF.html.
2. Sofowora A. (1993). Medicinal Plants and Traditional Medicine in Africa. Spectrum Books Ltd. Ibadan, Nigeria.
3. Trease G.E., Evans W.C. (1989). A Textbook of Pharmacognosy. Bailliere Tindall Ltd. London.