Alpha Glucosidase Inhibiting Activity and in vivo Antidiabetic Activity of Fraxinus floribunda Bark in Streptozotocin‑Induced Diabetic Rats

Background: Diabetes mellitus is a serious health problem being the third largest cause of death worldwide. Natural sources of antidiabetic agents are of high demand due to side effects of modern drugs. Bark of Fraxinus floribunda (FF) is conventionally used in Sikkim to treat diabetes, but there is not a single documented report on the same. Objective: The aim of this study is to evaluate in vitro and in vivo antidiabetic activity of FF bark. Materials and Methods: FF bark was extracted through four methods, namely normal boiling, pressure boiling (PB), soxhlet, and cold percolation to be subjected to α‑glucosidase inhibiting assay. The extract showing the highest in vitro antidiabetic activity was selected for in vivo antidiabetic activity. Results: Extract from PB showed the highest antidiabetic activity (10.25 ± 4.56 mg/ml FWT); thus, it was selected for antidiabetic property in animal model. The extracts (200 and 400 mg/kg) significantly (P < 0.05) reduced plasma glucose concentration in streptozotocin‑induced diabetic rats. Glibenclamide (0.50 mg/kg) was used as standard. Decrease in bodyweight during diabetes was significantly controlled by the extract which was comparable with the standard at the same concentration. Changes in lipid profile (total cholesterol, triglycerides, high‑density lipoprotein, and low‑density lipoprotein) of the diabetic rats were also maintained almost to the level of normal rats by the extracts. Histopathology of liver sections of diabetic rats showed damage in the hepatic architecture (swelling of sinusoids, vacuolization of cytoplasm, and inflammation of the central vein) which was controlled by the extracts. Conclusion: This study agrees with the traditional use of FF bark as an antidiabetic agent.