1,2,4‐Triazole‐based N‐heterocyclic carbene complexes of gold(I): synthesis, characterization and biological activity

Two gold(I) complexes of the (NHC)AuX type bearing a triazole-based N-heterocyclic carbene (NHC) ligand (1-tert-butyl-4-(4-methylphenyl)-3-phenyl-1H-1,2,4-triazol-4-ium-5-ylidene) and various halide ligands (X = Br, I) were synthesized and characterized in solution using NMR spectroscopy as well as in the solid state using X-ray diffraction techniques. The cytotoxic properties of both compounds and the precursor, (NHC)AuCl, were screened against a panel of human tumour cell lines including liver cancer (HepG2), cervical cancer (HeLa S3) and leukaemia (CCRF-CEM, HL-60) and compared to cisplatin and auranofin. It was found that the activities of the chloro and bromo derivatives were generally superior to that of cisplatin and slightly less effective compared to auranofin, except for HepG2 cells where auranofin was not as effective. In addition, the ability to induce membrane phosphatidyl serine externalization as a hallmark of apoptosis in CCRF-CEM leukaemic cells was investigated. Copyright © 2016 John Wiley & Sons, Ltd.