Gold(I) and gold(III) complexes of 1,2,4-triazole-derived N-heterocyclic carbenes: Synthesis, characterization, in-vitro anticancer and anti-inflammatory studies

Abstract

Two gold(I) and two gold(III) complexes featuring 1,2,4-triazole derived carbenes ([AuCl(Cy-tazy)] and [AuCl(Bn-tazy)]) have been successfully synthesized via a silver-carbene transfer pathway. Subsequent metal oxidations of using PhICl2 resulted in gold(III) complexes [AuCl3(Cy-tazy)] and [AuCl3(Bn-tazy)], respectively. All the complexes have been characterized by elemental analysis, multinuclear NMR spectroscopy, (ESI) mass spectrometry, single crystal X-ray diffraction and DFT calculations. In addition, all the four gold complexes exhibit high antiproliferative activities against KB, MCF-7 and HT-29 cancerous cell lines. The most active compound is also potent to Hela and leukemia (HL-60) cells but shows lower degree of cytotoxicity toward non-cancerous human embryonic kidney cells (HEK-293). Our preliminary studies also reveal that the two gold(III) complexes are capable of stabilizing red blood cell membrane and suppressing the NO production in RAW264.7 macrophages induced by lipopolysaccharides, suggesting their potential anti-inflammatory activities. Interestingly, there have hardly been any reports on anti-inflammatory activities of gold(III) complexes of N-heterocyclic carbenes.