Synthesis, spectroscopic characterization and anti-cancer properties of new gold(III)–alkanediamine complexes against gastric, prostate and ovarian cancer cells; crystal structure of [Au2(pn)2(Cl)2]Cl2·H2O

Abstract

A new series of Au(III) diamine complexes, with the general formulae [LAuCl2]Cl and [Au(L)2]Cl3 [where L=ethylenediamine (en), propylenediamine (pn), butylenediamine (bn) and N-alkyl substituted ethylenediamine (N-R-en)] was initially synthesized by reacting trihydrate auric acid (HAuCl4·3H2O) with 1 or 2 equivalents of the diamine ligands. These complexes have subsequently been characterized by elemental analysis, IR spectroscopy and NMR measurements. The IR data shows complexation of the diamine ligands to the Au(III) metal centre via N donor atoms. The solution and solid-state NMR data confirm the stability of the complexes due to the chelating effect of the diamine ligands. The crystal structure of one complex shows a dinuclear ionic complex with two discrete [Au(pn)(Cl)]+ units bridged by two deprotonated pn ligands and a pseudo square planar coordination geometry of the Au(III) ion. In this paper, the anti-cancer properties of gold(III) diamine complexes have also been evaluated in vitro against prostate PC3, gastric SGC7901 and ovarian A2780/A2780 ciscancer cells. Generally, [Au(diamine)2]3+ complexes demonstrate better anticancer properties in PC3 cells, whereas [Au(diamine)Cl2]+ displays better anticancer properties in SGC7901 and A2780/A2780 cis cells. The complex [Au(en)2]Cl3 is recognized as a cytotoxic agent that is as effective as cis-platin on prostate PC3 cancer cells.