Phytochemical Constituents, Anti-Diabetic and Antioxidant Activities of Methanol Extracts of Diospyros malabarica (Desr.) Kostel Leaves and Stem Bark

Abstract

Therefore, there is the need for a therapeutic agent that will reduce glucose absorption by inhibiting the action of carbohydrate hydrolyzing enzymes such as α-glucosidase, 2,3 inhibiting the action of the DPP-4 enzyme which plays a role in reducing glucagon secretion and stimulating insulin secretion from the pancreas, 2 and scavenging free radicals. Diabetes mellitus and its complications are associated with increased oxidative stress caused by free radicals. 3 Free radicals are compounds with unpaired electrons which make them unstable and very reactive. In order to attain a paired electron state and become stable, free radicals oxidizes biomolecules and cell organelles, thus inducing cell damage. 4 Most free radicals in the body are reactive oxygen species (ROS) consisting of superoxide anion (O2•-), alkoxyl radical (RO•) radical, hydroxyl radical (OH•), peroxyl radical (ROO•), and hydroperoxyl radical (HO2•), while nitric oxide (NO•), nitrite (NO2•), and nitrate radicals (NO3•) are termed the reactive nitrogen species (RNS). 5 Free radical activity causes physiological disturbances in cells; therefore, antioxidants are needed to neutralize or mitigate free radical levels to maintain cell physiological functions and contribute to disease prevention. Antioxidant activity protects the body against the damaging effects of oxidative stress due to hyperglycemia and can improve carbohydrate, protein and lipid metabolism and glucose absorption in people with diabetes mellitus. 6 Currently, several types of drugs are available for the treatment of diabetes including non-insulin anti-diabetic drugs such as sulfonylureas, biguanides, thiazolidinediones, α-glucosidase inhibitors, Dipeptidyl peptidase 4 (DPP-4) inhibitors, and Sodium-glucose cotransporter-2 (SGLT2) inhibitors. 7 However, the use of anti-diabetic