Improvement of the Anticancer Activities of Telmisartan by Zn(II) Complexation and Mechanisms of Action

To improve the anticancer activity of telmisartan, its structure has been modified by Zn(II) complexation giving [Zn(Telm)2(H2O)2]·2H2O (ZnTelm). The cytotoxic effect was measured on the human lung cancer cells (A549) and on the lung fibroblast cells (MRC-5). The complex markedly improved anticancer activity (IC50 75 μM) of telmisartan (IC50 125 μM) or ZnSO4 (IC50 225 μM) and did not show toxicity on non-cancer cells, inducing oxidative stress with cellular ROS generation and GSH/GSSG decrease. Apoptosis was the dominant form of cell death for the complex. The Bax/Bcl-XL ratio was significantly increased as well as caspase-3 activation. Both the complex and the ligand bind to bovine serum albumin (BSA) and can be stored and transported by the protein but the interaction with the complex is greater. Telmisartan binds BSA by hydrophobic interactions while the interaction of ZnTelm occurs through van der Waals forces and hydrogen bonding. Therefore, it can be shown that the coordination complex ZnTelm improved the anticancer activity of the antihypertensive drug telmisartan (IC50 75 μM and 125 μM, respectively) and the interaction with BSA.