Synthesis, characterization and anti proliferative effect of [Au(en)2]Cl3 and [Au(N-propyl-en)2]Cl3 on human cancer cell lines

Two Au(III) complexes of the type [Au(en)2]Cl3 (2a) and [Au(N-pr-en)2]Cl3 (3a) were synthesized by reacting Auric acid (HAuCl4·3H2O) with 2 equiv. ethylenediamine (en) or N-alkyl substituted ethylenediamine ligands. This metallodrug was characterized by various analytical and spectroscopic techniques such as elemental analysis, UV–Vis, Far-IR, 1H NMR and solution 13C as well as solid 13C and 15N NMR. Potentiality of [Au(en)2]Cl3 and [Au(N-pr-en)2]Cl3 as an anti-cancer agent were investigated by measuring some relevant physicochemical and biochemical properties such as stability of Au-N bonds by vibrational stretching from Far IR as well as cytotoxicity and stomach cancer cell inhibiting effect, respectively. The solid-state 15N NMR chemical shift shows that the ligand is strongly bound to gold(III) centre via N atoms. The computational study of 2a shows that the gold coordination sphere adopts distorted square planar geometry with bidentate ethylenediamine ligands acting as a tetradentate chelate. While stable in the solution state, the in vitro biological studies performed with these compounds 2a in solution showed higher activity towards the inhibitory effects of the human cancer cell lines such as prostate cancer (PC-3) and gastric carcinoma (SGC-7901) than that of the N-substituted gold(III) complex (3a). Cytotoxicity of the new compounds has also been estimated in PC-3 and SGC-7901 cells.

Graphical abstractTwo Au(III) complexes of the type [Au(en)2]Cl3 and [Au(N-pr-en)2]Cl3 were synthesized by reacting Auric acid (HAuCl4·3H2O) with 2 equiv. ethylenediamine (en) or N-alkyl substituted ethylenediamine ligands. This metallodrug was characterized by various analytical and spectroscopic techniques such as elemental analysis, UV–Vis, Far-IR, 1H NMR and solution 13C as well as solid 13C and 15N NMR. The following structure was determined by GAUSSIAN03 calculation.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Two complexes of [Au(en)2]Cl3 and [Au(N-pr-en)2]Cl3 (where en = ethylenediamine and N-pr-en = N-propyl ethylenediamine) were prepared and analyzed using various analytical techniques. ► The NMR and elemental analysis results strongly support the formation of a 1:2 complex of the type [Au(en)2]+3 complex with chelating ethylenediamine or substituted ethylenediamine ligands. ► The [Au(en)2]Cl3 seems be a promising chemo preventative and chemotherapeutic agent against human gastric carcinogenesis. ► As cytotoxic activity of [Au(en)2]Cl3 complex is high towards some cancer cell lines; further biological evaluation for this class of complexes is worthy of efforts especially in order to evaluate activities in vivo.