Phytochemical Investigation and In Vivo Antidiabetic Activity of Gongronema latifolium Leaf Fractions in Streptozotocin-Induced Diabetic Rats

Type 2 diabetes mellitus is a rapidly escalating chronic disease burden across Nigeria, with the South East zone recording increasing incidence driven by urbanisation and dietary transition. Gongronema latifolium, locally called utazi, is widely consumed and used medicinally for diabetes management in Igbo communities of South East Nigeria, yet systematic in vivo antidiabetic evaluations of its fractionated extracts are lacking. This study investigates the phytochemical composition and in vivo antidiabetic activity of successive methanol leaf fractions of Gongronema latifolium using a streptozotocin (STZ)-induced type 2 diabetic rat model. Diabetes was induced by a single intraperitoneal injection of STZ (45 mg/kg) following a high-fat diet pre-treatment protocol. Fractions obtained from column chromatography were screened for phytoconstituents and administered at 200 and 400 mg/kg for 28 days. Fasting blood glucose, serum insulin, HOMA-IR index, lipid profile, and pancreatic histopathology were evaluated. The ethyl acetate fraction significantly reduced fasting blood glucose levels, improved serum insulin, and corrected dyslipidaemia in a dose-dependent manner, with efficacy comparable to metformin at 400 mg/kg. Histopathological examination showed partial preservation of islet beta-cell architecture in fraction-treated animals. Identified active constituents included flavonoid glycosides and triterpenoid saponins. These findings provide the mechanistic basis for the antidiabetic ethnomedicinal use of Gongronema latifolium and recommend progression to clinical evaluation. Keywords: Gongronema latifolium, antidiabetic, streptozotocin, utazi, South East Nigeria