EPR examination of free radical properties of DOPA-melanin complexes with ciprofloxacin, lomefloxacin, norfloxacin and sparfloxacin

► Ciprofloxacin, lomefloxacin, norfloxacin and sparfloxacin form complexes with DOPA-melanin. ► Fluoroquinolones-melanin complexes are characterized by strong paramagnetism. ► Free radicals play an important role in fluoroquinolones binding to melanin. ► EPR spectroscopy is useful technique for examination of drugs binding to melanin.