Synthesis, characterization and antibacterial studies of a copper(II) lomefloxacin ternary complex.
Solution behavior of lomefloxacin (lmx) complexes with copper(II) in the presence and absence of 1,10-phenanthroline (phen) was studied in aqueous solution, by potentiometry. The results obtained showed that under physiological conditions (micromolar concentration range and pH7.4) only copper(II):lmx:phen ternary complexes are stable. Hence, a novel copper(II) ternary complex of lomefloxacin with the nitrogen donor heterocyclic ligand phen was synthesized and characterized by means of UV-visible and IR spectroscopy, elemental analysis and X-ray crystallography. In the synthesized complex (1), [Cu(lmx)(phen)(NO3)]·5H2O, lmx acts as a bidentate ligand coordinating the metal cation, in its anionic form, through the carbonyl and carboxyl oxygens and phen coordinates through two N-atoms forming the equatorial plane of a distorted square-pyramidal geometry. The fifth ligand of the penta-coordinated Cu(II) center is occupied axially by an oxygen atom from the nitrate ion. Minimum inhibitory concentration (MIC) determinations of the complex and comparison with free lomefloxacin in various E. coli strains indicated that the Cu-complex is an antimicrobial which is as efficient as the free antibiotic but strongly suggest that the cell intake route of both species is different. Moreover, spectrophotometric stability studies suggest that the solution of the complex synthesized is considerably more photostable than the free fluoroquinolone supporting, therefore, the complex's suitability as a candidate for further biological testing in fluoroquinolone-resistant microorganisms with possible reduced side-effects.
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
Patrícia
P
Fernandes
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
Isabel
I
Sousa
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
Luís
L
Cunha-Silva
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
Mariana
M
Ferreira
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
Baltazar
B
de Castro
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
Eulália F
EF
Pereira
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal. Electronic address: mffeio@fc.up.pt.
Maria J
MJ
Feio
REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
Paula
P
Gameiro
D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics; D003300:Copper / Q000737:chemistry* / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D004355:Drug Stability; D004926:Escherichia coli / Q000187:drug effects; D024841:Fluoroquinolones / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D011199:Potentiometry / Q000379:methods; D012996:Solutions; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
D000900:Anti-Bacterial Agents; D056831:Coordination Complexes; D024841:Fluoroquinolones; D012996:Solutions; D003300:Copper; C053091:lomefloxacin
Bacterial resistance; Fluoroquinolones; Lomefloxacin; Metalloantibiotics; Solution equilibria