engleski

Spectroscopic study of fluoroquinolone complexes with metal ions

It is well known that the absorption of quinolone antimicrobials is significantly reduced in the presence of several metal cations, due to metal ion-drug complexation. Thus, concomitant administration of metal ion containing drugs, e.g. Al, Mg or Ca containing antacid preparations, as well as drugs with Fe or Zn might antagonise the antimicrobial activity of fluoroquinolone. Our attention was focused on the complexation of three fluoroquinolones, ciprofloxacin (CF), norfloxacin (NF) and pefloxacin (PF) with following metal ions: Ca(II), Mg(II), Fe(II), Fe(III), Cu(II), Zn(II) and Al(III). The investigation was extended to health hazardous metals, e.g. Pb(II), Hg(II) and Cd(II), which sometimes could be present in higher concentrations in human body. The complexes were studied by UV/VIS, IR and 1D and 2D homo- and heteronuclear 1H and 13C NMR (COSY, NOESY and HETCOR) spectroscopies. The complexation depended on both fluoroquinolone derivative and metal ion type. The reactivity among fluoroquinolones was as it follow CF>NF>PF. Both, CF and NF interacted with all investigated metal ions, although NF poorly, while PF did not yield complexes with Al(III), Cd(II) and Pb(II) at all. The spectroscopic data indicate that beside carboxylic and keto groups at positions 3 and 4, respectively, more than one coordinating site in the fluoroquinolone structure exist, and it seems that N-1 and/or pyperazine nitrogen atoms are also involved in the complexation.

fluoroquinolone; ciprofloxacin; norfloxacin; pefloxacin; complexes; metal ions; IR spectroscopy; NMR spectroscopy

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