Synthesis, characterization and cytotoxicity of new gold(III) complexes with 1,2-diaminocyclohexane: Influence of stereochemistry on antitumor activity

Gold(III) complexes of the type [(DACH)AuCl2]Cl, derived from sodium tetrachloroaurate(III) dihydrate NaAuCl4 center dot 2H(2)O, where DACH is diaminocyclohexane, have been synthesized. These potential metallodrug compounds were characterized using various spectroscopic and analytical techniques, including elemental analysis, UV-Vis, infrared spectroscopy, solution as well as solid NMR spectroscopy and X-ray crystallography. The potential of the synthesized gold(III) complexes as anti-cancer agents was investigated by measuring some relevant physicochemical and biochemical properties, such as the stability of the Au-N bonds by vibrational stretching from far-IR as well as cytotoxicity and the stomach cancer cell inhibiting effect. The solid-state C-13 NMR chemical shift shows that the ligand is strongly bound to the gold(III) center via N atoms. An X-ray crystallography study of the complexes shows that the cyclohexyl ring adopts a chair conformation and the gold coordination sphere adopts a distorted square planar geometry. The cis isomer in solution showed higher activity towards the inhibitory effect of human cancer cell lines such as prostate cancer (PC-3) and gastric carcinoma (SGC-7901) than that of the trans isomer. The cytotoxicity of the cis isomer complex has also been estimated in PC-3 and SGC-7901 cells. (C) 2012 Elsevier Ltd. All rights reserved.