Aqueous Extract of Terminalia bellirica Fruits Improves Insulin Sensitivity, Controls Hyperglycaemia and Improves SIRT1 Expression in High-fat Diet and Streptozotocin-induced Type 2 Diabetes in Rats

Background: Plants from the genus “Terminalia” are well known for their various pharmacological and medicinal properties. Terminalia bellirica is considered a vital medicinal plant from the genus Terminalia. It has been reported for its astringent, antipyretic, and purgative effects. It is also used to treat dyspepsia, tropical pulmonary eosinophilia, allergic eruptions, bronchitis, upper respiratory tract infections, and leprosy. The present research study aimed to investigate the antidiabetic activity of T. bellirica in an experimental model of type 2 diabetes in experimental rats. Materials and Methods: In rats, type 2 diabetes was induced by the alteration in the diet by administration of a high-fat diet for 15 days, followed by the administration of streptozotocin (35 mg/kg, i.p.). The experimental animals were given 500 and 1,000 mg/kg of T. bellirica aqueous fruit extract for six weeks. Liver enzymes and lipid parameters, homeostatic model assessment–insulin resistance, insulin sensitivity index, glycohemoglobin, and oral glucose tolerance tests were performed at the end of the study. Histopathology and immunohistochemical analysis for the SIRT1 expression of pancreatic tissue were also performed. Results: The selected doses of the aqueous extract of T. bellirica (500 and 1,000 mg/kg) significantly reduced blood glucose ( p < .05). The 1,000 mg/kg dose of T. bellirica notably decreased glucose tolerance ( p < .001) in experimental animals. A high dose of T. bellirica significantly reduced resistance ( p < .001). The lipid profile was improved significantly ( p < .01) at both the selected dose levels. Glycohemoglobin concentration was significantly reduced in experimental animals ( p < .001) at both dose levels. The extract treatment increased the expression of SIRT1 in the pancreas. Conclusion: The results of the present study indicate that the extract has significant effects on the management of type 2 diabetes.