Photo -oxidation and non photo-oxidation of fluorinated quinolones and naphthyridones
The fluorinated quinolones (FQ) are a group of anti-infective quinolones containing one or more fluorine atoms in the molecule, and 2 types of ring structures; quinolones and naphthyridones. FQ have been reported to cause phototoxic reactions via unknown mechanisms and ROS might be the cause of this phototoxicity. The purpose of the study was to generate ROS; hydroxyl radical (Fenton reaction), peroxyl radical (AAPH reaction) and singlet oxygen (hypochlorite/peroxide reaction) under non photo-oxidation conditions and to study the effect of non photo-oxidation on the oxidative stability of the FQ. Enoxacin, alatrovafloxacin, and nalidixic acid were subjected to photo-oxidation (UV 254 and 365 nm) and reacted with hydroxyl radical, peroxyl radical and singlet oxygen reaction. HPLC methods for the analysis of reaction products were developed. Product structures for enoxacin were determined using LC-MS. Experimental results show that lomefloxacin, alatrovafloxacin, enoxacin, or nalidixic acid degradation products were observed with the Fenton, hypochlorite/peroxide, and at 254 and 365 nm reactions, but not with AAPH. The 254 nm reaction sample, formed degradation products were similar to those products from the Fenton reaction suggesting that hydroxyl radicals are largely responsible for the degradation of our model FQs. The 365 nm reaction sample gave less degradation products but similar to 254 nm reaction. Photo-oxidation reactions at 254 nm gave products with m/z 226, 251, 317, 319 (major) and 335. Reactions at 365 nm gave only m/z 317, 319 (major), and 335. The Fenton reaction (hydroxyl radicals) sample gave multiple products but only these at m/z 251 and 319 could be identified. Hypochlorite/peroxide sample show products resulting from reaction with hydroxyl radicals and singlet oxygen. The photo-oxidation at 254 and 365 nm exhibit mixed reactions from ROS.
0486: Analytical chemistry