The photoreaction of orbifloxacin (ORFX), a fluoroquinolone derivative having a fluorine at the 8 position, was investigated in aqueous solution containing chloride ion to determine its photochemical properties. In the presence of chloride ion, ORFX was found to convert into a photoproduct substituted by chlorine at the 8 position (8-Cl ORFX) under irradiation by ultraviolet-A (UVA) light. Although the formation rate of 8-Cl ORFX increased greatly with increase in chloride ion concentration, the apparent photodegradation rate of ORFX in aqueous solution was not varied by the presence of the ion. This implies that the dissociation of the C-F bond at the 8 position is the rate-limiting steps in the photodegradation of ORFX. The active oxygen generated by the photosensitization of ORFX were determined by measuring the bleaching rate of p-nitrosodimethylaniline and the reduction rate of cytochrome c. Their 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 between free radical and oxygen.
研究人员考察了奥比沙星(ORFX)在含
氯离子的
水溶液中的光反应,以确定其光
化学性质。ORFX 是一种
氟喹诺酮衍
生物,其 8 位上有一个
氟。研究发现,在
氯离子存在的情况下,ORFX 在紫外线-A(UVA)照射下会转化为一种 8 位被
氯取代的光产物(8-Cl ORFX)。虽然随着
氯离子浓度的增加,8-Cl ORFX 的形成率大大增加,但 ORFX 在
水溶液中的表观光降解率并不因
氯离子的存在而变化。这意味着 8 位 C-F 键的解离是 ORFX 光降解的限速步骤。通过测量对硝基二甲基
苯胺的漂白率和细胞色素 c 的还原率,确定了 ORFX 光敏化产生的活性氧。其机理被认为是 8 位上的光
氯化与自由基和氧之间的反应发生了竞争。