Jozef Miklovič, Miroslava Bašnárová, Peter Segľa and Marián Koman
The synthesis and characterization of eleven new Cu(II) and Co(II) complexes is reported. The complexes were characterized by elemental analyses, infrared and electronic spectra. Copper(II) with 3- methylthiophene-2-carboxylic acid (HMTK) forms a dinuclear complex of the acetate type [Cu2(MTK)4(H2O)2]. By reaction of this complex with 2-metylfuro[3,2-c]pyridine (MeFP), not only acetate type complexes [Cu2(MTK)4L2] (L= FP, MeFP) were obtained, but also monomeric complex [Cu(MTK)2(FP)2]. In the cases of benzofuro[3,2-c]pyridine (BFP) and 2-(3-trifluoromethylphenyl) furo[3,2-c]pyridine (CF3FP) only monomeric complexes [Cu(MTK)2L2] (L = BFP, CF3FP) were obtained. It is possible to observe, that with increasing amount of the ligand, the yield of monomeric complexes increases too. In monomeric complexes, the carboxylic group of anionic MTK binds to atom Cu(II) by asymmetrically chelating O,O-coordination. The crystal structure of the complex [Cu(MTK)2(MeFP)2] was determined by X-ray single crystal structure analysis. The copper(II) atom lies in the crystallographic centre of symmetry in an distorted tetragonal-bipyramidal arrangement. The structure of this complex confirms an asymmetric chelate coordination of the carboxylic group. HMTK and Cobalt(II) form coordination compound [Co(H2O)6](MTK)2 with assumed ionic mode of coordination of anionic MTK. With furopyridines monomeric complexes [Co(MTK)2L2] (L= FP, MeFP, BFP, CF3FP) with distorted octahedral coordination polyhedron around Co(II), were formed.
Barbora Kaliňáková, Daniela Hudecová, Peter Segľa, Martina Palicová and Jozef Švorec
Probable mode of action of new copper complexes of 2-methylthionicotinate (2-MeSNic) of composition [Cu(2-MeSNic)2(H2O)2] and [Cu(2-MeSNic)2(MeNia)2(H2O)2]·H2O (where MeNia is N-methylnicotinamide) is described. Both partial growth inhibition of Candida albicans (IC50 ≥ 1.78 mmol·L−1, MIC ≥ 2.5 mmol·L−1) and leak of proteins into the extracellular space (more than 80 %) were observed in the presence of these copper complexes. The membrane damage was detected by staining with Hoechst 33342, propidium iodide and methylene blue. Ascorbic acid potentiated antifungal activity of copper complexes approximately seven-fold and induced the oxidative stress, respectively. The production of intracellular reactive oxygen species was visualized by dichlorofluorescein. Thiobarbituric acid-reactive substances were formed as a by-product of lipid peroxidation.