Hypoglycemic effect of the methylene chloride-methanolic extract of the fresh and dried fruits of Gongronema latifolium in normoglycemic and alloxan-induced diabetic rats

Abstract

Ifeoma P. Okoli, Uduma E. Osonwa, Daniel L. Ajaghaku, Amarachukwu U. Anwuchaepe

Objective: The study investigated the hypoglycemic effect of the methylene chloride/ methanol (1:1) extracts (methylene methanolic extracts) of fresh and dried fruits of Gongronema latifolium in both normoglycemic and alloxan-induced diabetic animals. Activities of these extracts were also tested in combination with reference anti-diabetic drug—Glibenclamide. Methods: Qualitative screening for secondary metabolites and acute toxicities of the extracts was carried out using standard methods and modified Lorke’s method, respectively. Diabetes was induced intraperitoneally using alloxan monohydrate (120 mg/kg) and blood samples drawn by tail milking at 0 hour, 30 minutes, 1 hour, 2 hours, and 4 hours, respectively, for the determination of blood glucose. The extracts were tested at 50 and 100 mg/kg, while the combination study was tested at 50 mg/kg of the extracts +5 mg/kg gibenclamide in both alloxan-induced diabetic and normoglycemic rats. Results: Phytochemical analysis revealed the presence of varying amount of secondary metabolites such as alkaloids, glycosides, tannins, steroids, terpenoids, saponins, and resins. The acute toxicity tests indicated no obvious sign of toxicity or mortality. The fresh and dried fruit extracts produced significant (p < 0.05) dose-dependent hypoglycemic activities in both the normoglycemic and alloxan-induced hyperglycemic rats. Co-administration of the fresh fruit extract at 50 mg/kg and glibenclamide at 5 mg/kg showed a significantly (p < 0.05) increased activity over glibenclamide alone throughout the duration of the experiment. Conclusion: This study establishes the anti-diabetic activities of the fresh and dried fruits of G. latifolium and proves the treatment benefit in combining the methylene methanolic extract of this fruit with a standard oral hypoglycemic agent.