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

Abstract 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: [SAuPR 3 ]Cl, S = 3-benzyl-1,3-thiazolidine-2-thione, R = Ph or Et and [SAuPR 3 ] , 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.