Antibacterial Activity of Co(III) Complexes with Diamine Chelate Ligands against a Broad Spectrum of Bacteria with a DNA Interaction Mechanism

Abstract

Cobalt coordination complexes are very attractive compounds for their therapeutic uses as antiviral, antibacterial, antifungal, antiparasitic, or antitumor agents. Two Co(III) complexes with diamine chelate ligands ([CoCl2(dap)2]Cl (1) and [CoCl2(en)2]Cl (2)) (where dap = 1,3-diaminopropane, en = ethylenediamine) were synthesized and characterized by elemental analysis, an ATR technique, and a scan method and sequentially tested against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration results revealed that anaerobic and microaerophilic bacteria were found to be the most sensitive; the serial passages assay presented insignificant increases in bacterial resistance to both compounds after 20 passages. The synergy assay showed a significant reduction in the MIC values of nalidixic acid when combined with Compounds (1) or (2). The assessment of cell damage by the complexes was performed using scanning electron microscopy, transmission electron microscopy, and confocal microscopy, which indicated cell membrane permeability, deformation, and altered cell morphology. DNA interaction studies of the Co(III) complexes with plasmid pBR322 using spectrophotometric titration methods revealed that the interaction between Complex (1) or (2) and DNA suggested an electrostatic and intercalative mode of binding, respectively. Furthermore, the DNA cleavage ability of compounds by agarose gel electrophoresis showed nuclease activity for both complexes. The results suggest that the effect of the tested compounds against bacteria can be complex.

Crystallographic Structure and Quantum-Chemical Analysis of Biologically Active Co(III)-Pyridoxal–Isothiosemicarbazone Complex

“…For the positive control, Streptomycin, the zone of inhibition was 14 mm for E. coli and 17 mm for B. subtilis when the lowest concentration was considered. The activity of this compound was found to be greater than those of other Co(III), Zn(II), Ni(II), and Cu(II) complexes with analogous ligands, as reported in previous research [18,40,46]. This study demonstrated that complexes comprising thiosemicarbazone and semicarbazone ligands have a moderately high activity against E. coli and B. subtilis.…”

Anti-Helicobacter pylori Biofilm Extracts from Rubus idaeus and Rubus occidentalis

“…The effect of the plant extracts on the biofilm formed on the surface of intravenous infusion fragments was determined using SEM according to the procedure described by Turecka et al [ 31 ]. A JSM-6010LA scanning electron microscope from JEOL (Akishima, Tokyo, Japan), equipped with an EDX energy dispersive X-ray spectrometer, was used.…”

“…Identification of compounds was carried out on the basis of comparison with standard compounds and comparison of the obtained chromatographic data (Table 1) with data previously published by us [20,22,32]. All analyzed fruit extracts contained sanguiin H-6 (31), four isomers of sanguiin H-10 (3, 6, 21, 24), 8 sanguiin H-2 (28), quercetin 3-O-glucuronide (33), ellagic acid (27) and its pentoside (23), methylpentoside (35), and acetylpentoside (37). The fruits of the 'Poranna Rosa' variety were the only ones to contain epicatechin (14), while the presence of an additional pentoside of ellagic acid (25) was found in the fruits of the 'Laszka' variety.…”

Ru(II) Oxygen Sensors for Co(III) Complexes and Amphotericin B Antifungal Activity Detection by Phosphorescence Optical Respirometry

“…Coogan et al [22] showed that the Ru(II) coordination complex embedded within hydrodynamic diameter nanoparticles of polyacrylamide enters the analyzed cells. In our previous work [24], we showed that the newly synthesized FITC-labelled [Co(dap) 2 ]Cl 2 ([Co(dap) 2 FLU]Cl 2 ) penetrated the bacterial cell membrane and was evenly distributed inside bacterial cells. Using confocal microscopy and the mentioned properties of the tested compounds, it is possible to determine their binding site in Candida spp.…”