Evaluation of the oxidation of enrofloxacin by permanganate and the antimicrobial activity of the products.
Permanganate [Mn(VII)] oxidation of the fluoroquinolone (FQ) antibiotic enrofloxacin (ENR) was investigated with respect to kinetics and mechanisms, and the products were evaluated for residual antibacterial activity. The degradation of ENR by Mn(VII) obeyed second-order kinetics. A modern liquid chromatography coupled to a hybrid quadrupole time-of-flight mass spectrometer (LC-Q-TOF) was used to determine the accurate mass of the measured degradation products. The structures of nine oxidation products were identified at a neutral pH, one of which was an N-oxide product formed from the oxidation of tertiary amines. One proposed plausible reaction pathway was that the oxidation occurred on the piperazine ring; the C-H adjacent to the amine group was attacked by Mn(VII). The identified products from ENR arose through four pathways involving two mechanisms of N-dealkylation, C-hydroxylation and the reactions of amine oxides. The quinolone core remained intact for all of the products. The residual antibacterial activity of the oxidative reaction byproducts against the nonresistant Escherichia coli (G(-)) reference strain DH5ɑ was evaluated by quantifying the bacterial colonies. The oxidation products exhibited reduced antibacterial activity compared with their parent compound.
State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China. Electronic address: xuyongpeng@hit.edu.cn.
Yongpeng
Y
Xu
State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China.
Shiyao
S
Liu
Academy of Fundamental and Interdisciplinary Science, Harbin Institute of Technology, Harbin 150080, China.
Fang
F
Guo
School of Environmental Science & Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: zhangbo214@sjtu.edu.cn.
Bo
B
Zhang
D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D002853:Chromatography, Liquid; D000077422:Enrofloxacin; D004926:Escherichia coli / Q000187:drug effects*; D024841:Fluoroquinolones / Q000737:chemistry*; D007700:Kinetics; D017895:Manganese Compounds / Q000737:chemistry*; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*
D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D017895:Manganese Compounds; D010087:Oxides; C048856:permanganic acid; D000077422:Enrofloxacin
Antibacterial potency; Enrofloxacin; Mn(VII); Oxidation pathway; Product