Formulation and Comprehensive Evaluation of a Polyherbal Oil-in-Water Emulsion with Antidiabetic Activity in Streptozotocin-Induced Diabetic Rats

Abstract

Diabetes mellitus and dyslipidemia are closely associated metabolic disorders that increase the risk of cardiovascular and other chronic complications. Although synthetic drugs are effective, adverse effects, treatment costs, and limitations of combination therapy have increased interest in polyherbal alternatives. However, scientifically optimized herbal emulsions integrating multiple bioactive oils remain scarce. The aim was to develop and optimize an oil-in-water (O/W) polyherbal emulsion containing oils of Azadirachta indica, Syzygium aromaticum, Allium sativum, and Bombax ceiba, characterize its phytochemical composition by GC–MS, and evaluate its antidiabetic activity. Nine formulations (F1–F9) were prepared by wet-gum emulsification and optimized using a factorial design. F5 was selected based on physicochemical characteristics and evaluated in STZ-induced diabetic Wistar rats (n = 6/group). Animals received PHF (200 or 400 mg/kg) orally for 28 days. Blood glucose and body weight were assessed, and GC–MS characterized the major phytoconstituents. Statistical significance was set at p < 0.05. The optimized PHF produced significant, dose-dependent antihyperglycemic activity, markedly reducing fasting blood glucose compared with disease controls (p < 0.05). GC–MS identified pharmacologically important constituents, including eugenol, β-caryophyllene, eugenyl acetate, diallyl sulfur compounds, lupeol, β-sitosterol, and fatty acids, supporting potential synergistic and insulin-sensitizing effects. The optimized polyherbal O/W emulsion demonstrated significant antidiabetic activity and excellent acute safety. Its complementary phytoconstituents suggest multitarget therapeutic potential. Further pharmacokinetic, mechanistic, chronic toxicity, and clinical studies are warranted.