Protective effect of Gnetum africanum methanol leaf extract on pancreatic islet cells in rats

Laboratory rats have played a central role in studies of islet biology. Their islets have a well-defined structure with a central core of β-cells representing 60–80% of islet cells and a layer of other endocrine cells surrounding the core including α-cells, δ-cells, and pluripotent cells. Gnetum africanum is a leafy vegetable used in the management of diabetes by the people of Southern Nigeria. Despite its wide usage, its effect on alloxan-induced pancreatic cells is largely unknown. Its protective effect on pancreatic islets was studied using rats, in which diabetes was induced using alloxan (160 mg/kg). Diabetic rats were randomly divided into five groups (n = 10). Groups 1 and 2 received 10 ml/kg of distilled water and 2 mg/kg of glibenclamide respectively, while groups 3–5 received 200, 400, and 800 mg/kg of the extract. All treatments were performed daily for 21 days, after which they were sacrificed and the pancreas was taken for histopathology. Antioxidant activity of the extract was studied using in vitro (1,1-diphenyl-2-picrylhydrazine (DPPH)) and in vivo (superoxide dismutase (SOD)) models. The extract caused a dose-dependent reversal of islet destruction, especially at the dose of 800 mg/kg, produced an increase in antioxidant activity that was dependent on the concentration using DPPH assay, and significantly (p < 0.05) increased SOD levels compared to the control. These findings suggest that G. africanum protects against pancreatic islet destruction and validates its use in diabetes management.