Abstract
Four mixed-ligand metal(II) complexes with the molecular formulae [M(ofl)(bipy)]NO3�H2O and [M(ofl)(phen)]NO3�H2O were synthesized by the reaction of Co(II) and Ni(II) with ofloxacin (Hofl) in the presence of 1,10-phenanthroline (phen) / 2,2`-bipyridine (bipy) (1:1:1 molar ratio). The data obtained from elemental analysis, molar conductance, spectral infrared, reflectance spectra and magnetic studies gave information about the coordination of the ligands and the geometry of the metallic ion. The results suggest that Hofl is deprotonated and bidentately bound to the metal ion through the pyridone oxygen and the carboxylato oxygen while phen and bipy act as neutral bidentate ligands coordinated through the nitrogen atoms. Tetrahedral geometry is proposed for all complexes. Thermal analysis data led to useful information concerning the composition, dehydration and thermal behaviour of the complexes. Ofloxacin and the metal complexes were tested for antibacterial activity and also for antioxidant activity. The variations of physicochemical parameters were monitored, which explain the antibacterial behaviour of these compounds. The interactions between metal complexes and bacterial receptors have lower energy values compared to the ofloxacin ligand. The molecular docking studies allow the identification of the biological target and the predictions of the bonds between the studied compounds and the receptors of E. coli (3t88), S. aureus (3q8u) and P. aeruginosa (4lkd).
Highlights
In recent years, researchers have been trying to discover new chemical compounds in order to prevent microbial resistance to antibiotics which represents one of the major problems facing the medical world.Ofloxacin (Hofl), 7-fluoro-2-methyl-6-(4-methylpiperazin-1-yl)-10-oxo-4-oxa-1-azatricyclo [7.3. 1.05,13]trideca-5(13), 6,8,11-tetraene-11- carboxylic acid, is a second-generation fluoroquinolone drug which is active against both Gram positive and Gram-negative bacteria
The results suggest that Hofl is deprotonated and bidentately bound to the metal ion through the pyridone oxygen and the carboxylato oxygen while phen and bipy act as neutral bidentate ligands coordinated through the nitrogen atoms
The molar conductivities of metal complexes measured in 10-3 molL-1 DMF have high values (113-128 Ω-1cm2 mol1), which indicate their electrolyte nature [34]
Summary
Researchers have been trying to discover new chemical compounds in order to prevent microbial resistance to antibiotics which represents one of the major problems facing the medical world.Ofloxacin (Hofl), 7-fluoro-2-methyl-6-(4-methylpiperazin-1-yl)-10-oxo-4-oxa-1-azatricyclo [7.3. 1.05,13]trideca-5(13), 6,8,11-tetraene-11- carboxylic acid, is a second-generation fluoroquinolone drug which is active against both Gram positive and Gram-negative bacteria. Ofloxacin functions by inhibiting DNA gyrase - an enzyme necessary to separate replicated DNA- thereby inhibiting bacterial cell division [1]. One of the main objectives when obtaining ofloxacin metal complexes was to ascertain the nature of the functional groups responsible for metal-ligand binding [2,3]. There are reports in the literature about the synthesis, structural characterization and antibacterial activity of ofloxacin metal complexes [4,5,6,7,8]. It was found that when a nitrogen-donating coligand (1,10-phenanthroline or 2,2'-bipyridine) is added in the coordination sphere, in addition to ofloxacin which is the primary ligand, the obtained complexes show a much improved antibacterial activity. It is known that 1,10-phenanthroline and 2,2'-bipyridine present considerable interest in coordination chemistry as chelating bidentate ligands for transition metal ions
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