Antidiabetic Activity of Extracts of Terminalia brownii Fresen. Stem Bark in Mice

Background: Diabetes mellitus is a chronic metabolic disorder that imposes a huge health and economic burden on societies. Because the currently available medications have many drawbacks, it is important to search for alternative therapies. Medicinal plants used in traditional medicines are ideal candidates. Hence, this study was undertaken to investigate the antidiabetic activity of crude extract and solvent fractions from the stem bark of Terminalia brownii Fresen. (Combretaceae) in mice. Materials and Methods: The in vitro alpha-amylase inhibition assay was performed using the chromogenic 3, 5-dinitrosalicylic acid (DNSA) method while the antihyperglycemic activity was assessed using three mouse models: streptozotocin-induced diabetic mice, normoglycemic mice, and oral glucose challenged mice. Experimental diabetes was induced by a single intraperitoneal injection of streptozotocin at a dose of 150 mg/kg and animals with fasting blood glucose level (BGL) >200 mg/dL were considered diabetic. Glibenclamide (5 mg/kg) was used as a standard drug. Fasting BGL and body weight were used to assess the antidiabetic activity. The result was analyzed using GraphPad Prism software version 8 and one-way ANOVA followed by Tukey's post hoc test with p<0.05 considered as statistically significant. Results: The crude extract of T. brownii at all tested dose levels (250, 500 and 750 mg/kg) showed a significant BGL reduction in all the three animal models. Moreover, the ethyl acetate and aqueous fractions (at 500 mg/kg) significantly (p<0.01) reduced the BGL in the streptozotocin induced diabetic model. The crude extract and different solvent fractions also showed a dose-dependent in vitro alpha-amylase inhibitory activity and improvement of body weight. Conclusion: T. brownii crude extract and its solvent fractions showed a significant antihyperglycemic activity in STZ induced diabetic mice, hypoglycemic activity and improvement of oral glucose tolerance in normal mice.