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

•Gold(I) complexes containing phosphine and heterocyclic compounds were synthesized.•All compounds exhibited high cytotoxicity and present high selectivity index. Complex 3 exhibited high cytotoxicity in melanoma and colon cells.

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.

Graphical abstract[C28H26NPS2Au]Cl (1), [C16H26NPS2Au]Cl (2), C26H20N2OPSAu (3) and C14H20N2OPSAu (4) were obtained with 3-benzyl-1,3-thiazolidine-2-thione or 5-phenyl-1,3,4-oxadiazole-2-thione and phosphines. The compounds were more cytotoxic than cisplatin to colon cancer (CT26WT) and metastatic skin melanoma (B16F10) tumor cell lines.Figure optionsDownload full-size imageDownload as PowerPoint slide