Antidiabetic activity of aqueous and methanol extract and fractions of Gongronema latifolium (Asclepidaceae) leaves in Alloxan Diabetic Rats

Rural dwellers in Nigeria often resort to herbal remedy and dietary control in the treatment of diabetes mellitus (DM). This work was undertaken to provide the rationale for the use of the leaves of Gogronema latifolium as a traditional antidiabetic agent. Methanol extract (ME) of the leaves of G. latifolium was prepared by soxhlet extraction while the aqueous extract (AE) was prepared by cold maceration. The methanol extract was separated into fractions by column chromatography to yield methanol fraction (MF), n-hexane fraction (HF) and chloroform fraction (CF).The extract and the fractions were evaluated for antidiabetic effect in alloxan-induced diabetes in rats. The blood sugar levels were assayed as indices of diabetes. The phytochemical analyses of the extracts and fractions as well as the LD50 of the ME were determined. The results indicated that intraperitoneal injection of AE, ME, CF, HF, and MF, (200-800 mg/kg/day) exhibited a significant (P<0.05) anti-diabetic effect by ameliorating alloxan-induced increase in blood sugar. Antidiabetic potency of the extracts and fractions was in the order; MF> ME> AE>HF>CF. Phytochemical analysis of the extracts and fractions indicated high concentration of proteins, flavonoids, saponins, alkaloids, terpenoids, and steroids while tannins, reducing sugar and acidic compounds were absent. The LD50 of the methanol extract was calculated to be 900mg/kg. The results of this study lead credence to the use of G. latifolium in the management of diabetes mellitus.