Investigation of the Antidiabetic Potential of Combination of Newbouldia leavis (P. Beauv) Leaves and Garcinia kola (Hackel) Seed Extracts in NAD – Streptozin Induced Diabetes

Background: Type 2 diabetes mellitus (T2DM) is a widespread metabolic disorder characterized by insulin resistance and impaired insulin secretion, leading to hyperglycemia and various complications. Despite the availability of conventional therapies, achieving optimal glycemic control remains a challenge, necessitating alternative treatment strategies. Ethnomedicinal evidence suggests that Newbouldia laevis (P. Beauv) leaves and Garcinia kola (Hackel) seeds possess hypoglycemic properties, but their combined antidiabetic potential remains underexplored. Objective: This study investigates the antidiabetic efficacy of N. laevis and G. kola extracts individually and in combination, aiming to develop a synergistic polyherbal formulation for diabetes management. Methods: The study involved phytochemical screening, acute toxicity assessment, and in vivo evaluation of antidiabetic activity using a nicotinamide-streptozotocin (NAD-STZ) induced diabetic model in Swiss albino mice. The median effective doses (ED₅₀) of the individual extracts were determined, followed by an isobologram analysis to assess the interaction between the two plant extracts. Mice were divided into treatment groups receiving different combinations of N. laevis and G. kola extracts, alongside standard antidiabetic drugs as controls. Biochemical parameters, including fasting blood glucose (FBG), lipid profile, insulin secretion, and insulin resistance indices, were evaluated over 12 weeks. Results: Phytochemical analysis confirmed the presence of bioactive compounds such as flavonoids, saponins, and terpenoids in both extracts. Acute toxicity studies showed no mortality at doses up to 5000 mg/kg, indicating safety. Both extracts significantly reduced FBG levels in a dose-dependent manner, with G. kola exhibiting superior glucose-lowering effects. The combination therapy demonstrated a synergistic effect, achieving enhanced glycemic control and lipid modulation compared to individual treatments. The most effective combination ratio (110 mg/kg G. kola: 160 mg/kg N. laevis) showed significant improvements in insulin sensitivity, glucose tolerance, and lipid profiles. Conclusion: The synergistic interaction between N. laevis and G. kola offers a promising alternative for diabetes management. This combination not only improves glycemic control but also addresses metabolic complications associated with T2DM, potentially serving as a foundation for novel polyherbal formulations. Further clinical investigations are warranted to validate these findings for human application.