Synthesis and cytotoxic activity of gold(I) complexes containing phosphines and 3-benzyl-1,3-thiazolidine-2-thione or 5-phenyl-1,3,4-oxadiazole-2-thione as ligands

Heterocyclic compounds and their metal complexes display a broad spectrum of pharmacological properties. This work reports the preparation and characterization of four novel gold(I) complexes containing tertiary phosphine and 3-benzyl-1,3-thiazolidine-2-thione, 5-phenyl-1,3,4-oxadiazole-2-thione as ligands. The reaction of chloro(triphenylphosphine) gold(I) and chloro(triethylphosphine) gold(I) with thioamides, 3-benzyl-1,3-thiazolidine-2-thione and 5-phenyl-1,3,4-oxadiazole-2-thione in dichloromethane or dichloromethane/acetone resulted in the formation of the gold(I) complexes of general formula: [SAuPR3] Cl, S = 3-benzyl-1,3-thiazolidine-2-thione, R = Ph or Et and [SAuPR3], S = 5-phenyl-1,3,4-oxadiazole-2-thione, R = Ph or Et. Spectroscopic evidence suggested that gold is coordinated to the exocyclic sulfur atom in all cases and this was confirmed by X-ray crystallographic data obtained for complex (4). The cytotoxicity of the compounds has been evaluated in comparison to cisplatin in two different tumor cell lines, colon cancer (CT26WT) and metastatic skin melanoma (B16F10), and also in a kidney normal cell (BHK-21). The gold complexes showed a better activity than cisplatin and presented a high selectivity index. (C) 2014 Elsevier B. V. All rights reserved.