Synthesis, structural and antimicrobial studies of type II topoisomerase-targeted copper(II) complexes of 1,3-disubstituted thiourea ligands.

A series of Cu(II) complexes of 3-(trifluoromethyl)phenylthiourea derivatives was synthesized. Their structural properties were investigated by spectroscopic techniques (infrared and electron paramagnetic resonance), as well as molecular modeling. All studied coordination compounds are mononuclear complexes containing two chelating ligands bonded to the metal cation via S and deprotonated N atoms. The new chelates were evaluated for their antimicrobial potency. The complex of 1-(3,4-dichlorophenyl)-3-[3-(trifluoromethyl)phenyl]thiourea (3) presented the highest activity against Gram-positive pathogens, even stronger than the activity of its non-complexed counterpart and the reference drug. The compound also prevented the biofilm formation of methicillin-resistant and standard strains of staphylococcal cocci. The title derivatives were found to be effective inhibitors of DNA gyrase and topoisomerase IV isolated from Staphylococcus aureus. The binding modes of the ligand L3 with DNA gyrase and topoisomerase IV were presented.