In vitro phototoxic activities of new quinolone antibacterial agents: lipid peroxidative potentials.

To determine the fundamental photochemical properties of new quinolones that can induce photosensitivity, the in vitro phototoxicity of these drugs (enoxacin, norfloxacin, ofloxacin, ciprofloxacin, and lomefloxacin) was examined with respect to photosensitizing ability to peroxidize unsaturated lipid squalene in ethanol solution. Lomefloxacin and ciprofloxacin showed the highest efficiency in sensitization of peroxidation of the lipid. Moderate repression of peroxidation occurred by addition of sodium azide (a quencher of singlet molecular oxygen), suggesting that the nonsinglet oxygen mechanism is operative in addition to the singlet oxygen mechanism.