title: Synthesis, characterization and antibacterial studies of a copper(II) levofloxacin ternary complex.
abstract: Solution behavior of levofloxacin (lvx) complexes with copper(II) in the presence and absence of phen was studied in aqueous solution, by potentiometry. The results obtained show that under physiological conditions (micromolar concentration range and pH 7.4) only copper(II):lvx:phen ternary complexes are stable. Hence, a novel copper(II) ternary complex of fluoroquinolone levofloxacin with 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(lvx)(phen)(H(2)O)](NO(3)).2H(2)O, levofloxacin acts as a bidentate ligand coordinating to the metal, 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) centre is occupied axially by an oxygen atom from a water molecule. Minimum inhibitory concentration (MIC) determinations of the complex and comparison with free levofloxacin in various E. coli strains indicated that the Cu-complex is as efficient an antimicrobial as the free antibiotic (both in the case of the dissolved synthesized complex and the complex formed following stoichiometric mixture of the individual components in solution). Moreover, results strongly suggest that the cell intake route of both species is different supporting, therefore, the complex's suitability as a candidate for further biological testing in fluoroquinolone-resistant microorganisms.
authors.affiliation: Requimte, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Sousa
authors.forename: Vasco
authors.initials: V
authors.lastname: Claro
authors.forename: João Lino
authors.initials: JL
authors.lastname: Pereira
authors.forename: Ana Luísa
authors.initials: AL
authors.lastname: Amaral
authors.forename: Luís
authors.initials: L
authors.lastname: Cunha-Silva
authors.forename: Baltazar
authors.initials: B
authors.lastname: de Castro
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Feio
authors.forename: Eulália
authors.initials: E
authors.lastname: Pereira
authors.forename: Paula
authors.initials: P
authors.lastname: Gameiro
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D003300:Copper / Q000737:chemistry / Q000494:pharmacology; D004926:Escherichia coli / Q000254:growth & development*; D004927:Escherichia coli Infections / Q000188:drug therapy; D064704:Levofloxacin; D015242:Ofloxacin / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D064704:Levofloxacin; D003300:Copper; D015242:Ofloxacin