Radiation-induced in vitro phototoxic potential of some fluoroquinolones

Photosensitizing drugs that can damage cellular biomolecules is a matter of concern. Lomefloxacin, norfloxacin, ofloxacin, and enoxacin (broad-spectrum antibiotics of fluoroquinolone group) are used for the treatment of Gram-positive and Gram-negative bacterial infections. Phototoxicity and possible mechanism of their action was assessed under the exposure of ambient levels of UV-A, UV-B, and sunlight at a concentration generally used in the treatment of various diseases. Singlet oxygen (O-1(2)), superoxide anion radical (O-2(-)) generation, DNA damage, and lipid peroxidation in human blood were studied. All the fluoroquinolones tested in this study produced O-1(2) and O-2(-) under exposure to UV-A, UV-B, and sunlight depending on the concentrations (0 to 60 mu g/mL) of the drugs. Enoxacin showed a higher yield of O-1(2) and O-2(-) than other drugs. These materials also degraded deoxyguanosine and induced lipid peroxidation in vitro under exposure to UV-A, UV-B, and sunlight (depending on the dose of radiation). The formation of the reactive oxygen species (ROS) by the photoexcited drugs may be considered as a possible mechanism of their action.