PHOTOREACTION AND ACTIVE OXYGEN GENERATION BY PHOTOSENSITIZATION OF ANEW ANTIBACTERIAL FLUOROQUINOLONE DERIVATIVE, ORBIFLOXACIN, IN THE PRESENCE OF CHLORIDE-ION
T. Morimura et al., PHOTOREACTION AND ACTIVE OXYGEN GENERATION BY PHOTOSENSITIZATION OF ANEW ANTIBACTERIAL FLUOROQUINOLONE DERIVATIVE, ORBIFLOXACIN, IN THE PRESENCE OF CHLORIDE-ION, Chemical and Pharmaceutical Bulletin, 45(11), 1997, pp. 1828-1832
The photoreaction of orbifloxacin (ORFX), a fluoroquinolone derivative
having a fluorine at the 8 position, was investigated in aqueous solu
tion containing chloride ion to determine its photochemical properties
, In the presence of chloride ion, ORFX was found to convert into a ph
otoproduct substituted by chlorine at the 8 position (8-Cl ORFX) under
irradiation by ultraviolet-A (WA) light, Although the formation rate
of 8-Cl ORFX increased greatly with increase in chloride ion concentra
tion, the apparent photodegradation rate of ORFX in aqueous solution w
as not varied by the presence of the ion, This implies that the dissoc
iation of the C-F bond at the 8 position is the rate-limiting step in
the photodegradation of ORFX. The active oxygen generated by the photo
sensitization of ORFX were determined by measuring the bleaching rate
of p-nitrosodimethylaniline and the reduction rate of cytochrome c. Th
eir generation was inhibited by sodium azide and superoxide dismutase
but not by D-mannitol, The photoreaction between ORFX and chloride ion
also inhibited their generation, The mechanism is believed to be the
photochlorination at the 8 position competing with the reaction betwee
n free radical and oxygen.