The Effect of Drying Conditions on the Antidiabetic Activity of the Ethanolic Leaf Extract OFof Vernonia Amygdalina

Abstract

Ethanolic extracts of the leaves of Vernonia amygdalina were obtained by maceration from the freshly -harvested leaves, leaves dried in the shade, and leaves dried at 40 °C in the hot air oven. Solvent removal was achieved with the aid of a rotary evaporator. White albino rats of both sexes weighing 90-145 g were used. Diabetes was induced with alloxan given i.p. at a dose of 150 mg/kg body weight. The animals were randomized into 8 groups of 5 animals per group. After a 12 hr overnight fast, each group treated as follows: group 1 received 50 mg/kg of fresh leaves extract; group 2 received 50 mg/kg of shade-dried leaves extract; group 3 received 50 mg/kg of oven-dried leaves extract; group 4 received 100 mg/kg of fresh leaves extract; group 5 received 100 mg/kg of shade-dried leaves extract; group 6 received 100 mg/kg of oven-dried leaves extract; group received Glibenclamide 10 mg/kg while group 8 received 2 ml/kg distilled water. Fresh blood obtained from the rat tail vein was analyzed for blood glucose level at 0, 1,2,4,6,8,12 and 24 hr from the time of administration with a glucometer. Free access to both food and water was allowed immediately after drug administration. Analysis of variance of the results was carried out with Microsoft SPSS^® software at a 5 % level of significance. The results show that at 50 mg/kg dose of extract, the hypoglycemic activities were in the order: shade-dried leaves extract > fresh leaves extract> glibenclamide (10 mg/kg)> oven-dried leaves extract > water. The hypoglycemic effects of the leaves extracts were significant up till 6 hr; thereafter the blood glucose started rising again. Hypoglycemic activity significantly (p<0.05) increased with increase in extract dose. Thus, the shade-dried leaves extract was more effective weight for weight than either the oven-dried or fresh leaves extracts as an antidiabetic agent when compared weight per weight.

Keywords: Diabetes mellitus, Vernonia amygdalina, drying conditions, blood glucose-lowering

Nigerian Journal of Pharmaceutical Research Vol. 8 No 1 pp. 12 - 18