Synthesis, X-ray structures and anticancer activity of gold(I)-carbene complexes with selenones as co-ligands and their molecular docking studies with thioredoxin reductase

Abstract

Five new gold(I) complexes of carbene and selenone ligands (1–5) having the general formula, [Au(IPr)(selenone)]PF6 were synthesized by the reaction of [Au(IPr)Cl] (0) with selenones (IPr = 1,3-Bis(2,6-di-isopropylphenyl)imidazol-2-ylidene and selenone = 1,3-imidazolidine-2-selenone, N-ethyl-1,3-imidazolidine-2-selenone, N-propyl-1,3-imidazolidine-2-selenone, N,N′-dimethyl-1,3-imidazolidine-2-selenone and N,N′-diethyl-1,3-imidiazolidine-2-selenone for 1–5 respectively). The complexes were characterized by elemental analysis, IR and NMR (1H, 13C, 77Se) spectroscopy, and two of them by X-ray crystallography. The X-ray diffraction analysis of complexes 2 and 4 revealed that they were composed of [Au(IPr)(Selenone)]+ and PF6− ions. In the complex ions, gold(I) atom adopts a linear geometry. In vitro cytotoxicity was appraised for all complexes against HCT15, A549 and MCF7 cancer cell lines. The IC50 values showed that the complexes exhibited poor activity as compared to cisplatin. However, the complex 1 showed a promising anticancer activity (IC50 = 33 ± 1 μM) similar to that exhibited by cisplatin (32 ± 2 μM) against HCT15 (human colon cancer) cell line. The molecular docking analysis showed the potential inhibitory capacity of the gold complexes with thioredoxin reductase with complex 4 having the highest binding affinity with a score of −34.45. The interactions of the gold complexes with tryptophan and lysozyme were studied electrochemically using Cyclic and Square Wave Voltammetry.