Phytochemical Screening, Acute Toxicity study and Evaluation of Antidiabetic properties of the methanolic leaf extract of Vernonia glaberrima (Asteraceae)

Vernonia species, family Asteraceae, have been used for the treatment of diabetes mellitus and various other ailments in traditional medicine. Vernonia glaberrima is employed traditionally in Northern Nigeria for treating malaria, pain, dysmenorrhea, inflammation and microbial infections. The plant material was pulverized and macerated using methanol. Phytochemical screening was conducted on the crude methanol extract to test for the presence of secondary metabolites. Acute toxicity study of the crude extract was conducted (i.p.) using Swiss albino mice. The antidiabetic effect of the extract was evaluated by normoglycemic, glucose tolerance test and alloxan-induced diabetic models. The results of the phytochemical screening indicated the presence of flavonoids, saponins, tannins, steroids, glycosides, terpenes and alkaloids. The lethal dose (LD50) was found to be 1265mg/kg suggesting the plant to be fairly toxic. The crude extract (300mg/kg) exhibited significant (p˂0.05) hypoglycemic activity in alloxan-induced diabetic model when compared to the control but did not show significant change in the normoglycemic and oral glucose tests. These results suggest that the extract has a moderate hypoglycemic effect and may potentially be used for the treatment of diabetes mellitus without a major drawback of hypoglycemia. Keyword: Vernonia glaberrima extract; Diabetes mellitus; blood glucose; phytochemical screening