Rhenium complexes with the antibiotic cip
rofloxacin have been p
repa
red to be studied as models of technetium
radiopha
rmaceuticals. With this aim, the new
rhenium complexes
rong class="boldFont">1rong> {[ReO(Cpf)
2]Cl},
rong class="boldFont">2rong> {[ReO(CpfH)
2]Cl
3} and
rong class="boldFont">3rong> {
fac-[Re(CO)
3(H
2O)(Cpf)]} with cip
rofloxacin (CpfH = cip
rofloxacin; Cpf = conjugated base of cip
rofloxacin) have been synthesised and cha
racte
rised by elemental analyses, IR, NMR (
1H,
19F and
13C CP-MAS) spect
roscopy, as well as MS measu
rements. All spect
roscopic data a
re consistent with the coo
rdination of cip
rofloxacin in all these complexes th
rough the ca
rbonyl and the ca
rboxylate oxygen atoms with the fo
rmation of a six membe
r chelate
ring.
The study of a Tc-ciprofloxacin solution by ESI–MS reveals the presence of [TcO(Cpf)2]+ cations, which agrees with the hypothesis that complexes rong class="boldFont">1rong> and rong class="boldFont">2rong> can be seen as model rhenium complexes of this radiopharmaceutical.
Antimicrobial and DNA gyrase inhibition studies performed with complexes rong class="boldFont">2rong> and rong class="boldFont">3rong> have shown a very similar behaviour between complex rong class="boldFont">2rong> and the free antibiotic, whereas complex rong class="boldFont">3rong> exhibit a lower antimicrobial activity.
Based on a joint analysis of the data reported in the literature and the chemical and biological results obtained in this study, a tentative proposal to explain some aspects of the behaviour of Tc-ciprofloxacin radiopharmaceutical has been made.