Antidiabetic and Pancreato-Protective Activity of Polyphenol-Rich Extract of Irvingia gabonensis Seed in a High-Fat Diet Streptozotocin Model

Irvingia gabonensis, commonly called wild mango or ogbono, is widely consumed in the South East and South South zones of Nigeria, where the seed is used as both a food thickener and a traditional remedy for diabetes and dyslipidaemia. The polyphenol and fibre-rich composition of Irvingia gabonensis seed suggests pleiotropic mechanisms of potential antidiabetic utility, yet in vivo evidence using a pathophysiologically relevant type 2 diabetes model is absent. This study evaluates the antidiabetic and pancreato-protective activity of a polyphenol-rich aqueous extract of Irvingia gabonensis seed kernel in a high-fat diet combined with low-dose streptozotocin (HFD-STZ) rat model, which recapitulates human type 2 diabetes phenotype. After 8 weeks of HFD feeding, diabetes was confirmed by STZ (35 mg/kg, i.p.) and fasting blood glucose measurement. Diabetic rats received extract at 200 and 400 mg/kg for 28 days, with metformin (200 mg/kg) as the reference drug. Outcome measures included fasting blood glucose, insulin, HOMA-IR, HbA1c, lipid profile, and pancreatic histopathology with immunohistochemical staining for insulin and glucagon. The 400 mg/kg extract significantly reduced fasting blood glucose, improved HOMA-IR, and partially restored islet cell architecture on histopathology. Immunohistochemistry showed preservation of insulin-positive beta-cell area. Polyphenol-PPARG and GLP-1 receptor interaction was proposed as the primary mechanism based on pathway gene expression analysis. These results support Irvingia gabonensis seed as a candidate for antidiabetic functional food and phytomedicine development. Keywords: Irvingia gabonensis, antidiabetic, streptozotocin, pancreato-protective, ogbono