Distinct Properties of Telmisartan on Agonistic Activities for Peroxisome Proliferator-Activated Receptor g among Clinically Used Angiotensin II Receptor Blockers: Drug-Target Interaction Analyses

A proportion of angiotensin II type 1 receptor blockers (ARBs) improves glucose dyshomeostasis and insulin resistance in a clinical setting. Of these ARBs, telmisartan has the unique property of being a partial agonist for peroxisome proliferatoractivated receptor g (PPARg). However, the detailed mechanism of how telmisartan acts on PPARg and exerts its insulinsensitizing effect is poorly understood. In this context, we investigated the agonistic activity of a variety of clinically available ARBs on PPARg using isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) system. Based on physicochemical data, we then reevaluated the metabolically beneficial effects of telmisartan in cultured murine adipocytes. ITC and SPR assays demonstrated that telmisartan exhibited the highest affinity of the ARBs tested. Distribution coefficient and parallel artificial membrane permeability assays were used to assess lipophilicity and cell permeability, for which telmisartan exhibited the highest levels of both. We next examined the effect of each ARB on insulin-mediated glucosemetabolism in 3T3-L1 preadipocytes. To investigate the impact on adipogenesis, 3T3-L1 preadipocytes were differentiated with each ARB in addition to standard inducers of differentiation for adipogenesis. Telmisartan dose-dependently facilitated adipogenesis and markedly augmented the mRNA expression of adipocyte fatty acid-binding protein (aP2), accompanied by an increase in the uptake of 2-deoxyglucose and protein expression of glucose transporter 4 (GLUT4). In contrast, other ARBs showed only marginal effects in these experiments. In accordancewith its highest affinity of binding for PPARg as well as the highest cell permeability, telmisartan superbly activates PPARg among the ARBs tested, thereby providing a fresh avenue for treating hypertensive patients with metabolic derangement.