Terpenoids: An Activator of “Fuel-Sensing Enzyme AMPK” with Special Emphasis on Antidiabetic Activity

Abstract

The past decade has witnessed a tremendous resurgence in the interest and use of medicinal plants. The therapeutic effects of these medicinal plants can justifiably be attributed to the phytochemicals in them especially the flavonoids, alkaloids, sterols, terpenoids, phenolic acids, stilbenes, lignans, tannins, and saponins. Terpenoids comprise one of the most interesting groups of natural products; due to their diverse pharmacological activities, such compounds can either be used directly as active compounds or modified to increase their selectivity and potency. Type 2 diabetes is one of the fastest-growing public health problems worldwide characterized by the abnormal glucose and lipid metabolism due in part to resistance to the actions of insulin in the skeletal muscle, liver, and fat. This may result from inadequate adaptation to environmental changes (e.g., imbalance between energy intake and energy expenditure). AMP-activated protein kinase (AMPK), a phylogenetically conserved serine/threonine protein kinase, acts as an integrator of regulatory signals monitoring systemic and cellular energy status. The growing realization that AMPK regulates the coordination of anabolic (synthesis and storage of glucose and fatty acids) and catabolic (oxidation of glucose and fatty acids) metabolic processes represents an attractive therapeutic target for intervention in many conditions of disordered energy balance. Recent evidences that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profile, and blood pressure in insulin-resistant rodents make this protein kinase a novel therapeutic target in the treatment of type 2 diabetes. The present review provides updates on wide range of biological activities of terpenoids in activating AMPK and thereby regulating type 2 diabetes.