Conjugation of Ciprofloxacin with Poly(2-oxazoline)s and Polyethylene Glycol via End Groups

The antibiotic ciprofloxacin (CIP) was covalently attached to the chain end of poly­(2-methyloxazoline) (PMOx), poly­(2-ethyloxazoline) (PEtOx), and polyethylene glycol (PEG), and the antimicrobial activity of these conjugates was tested for <i>Staphylococcus aureus</i>, <i>Streptococcus mutans</i>, <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, and <i>Kleisella pneumoniae.</i> Chemical structures of the conjugates were proven by ¹H NMR and electron spray ionization mass spectrometry. The direct coupling of PMOx and CIP resulted in low antimicrobial activity. The coupling via a spacer afforded molecular weight dependent activity with a molar minimal inhibitory concentration that is even higher than that of the pristine CIP. The antimicrobial activity of the conjugates increases in the order of PMOx < PEtOx < PEG. Conjugation of CIP and a quaternary ammonium compound via PMOx did not result in higher activity, indicating no satellite group or synergistic effect of the different biocidal end groups