title: Direct Photolysis of Fluoroquinolone Antibiotics at 253.7 nm: Specific Reaction Kinetics and Formation of Equally Potent Fluoroquinolone Antibiotics.
abstract: Three fluoroquinolone-to-fluoroquinolone antibiotic transformations were monitored during UV-C irradiation processes. In particular, the following reactions were observed: enrofloxacin-to-ciprofloxacin, difloxacin-to-sarafloxacin, and pefloxacin-to-norfloxacin. The apparent molar absorptivity and fluence-based pseudo-first-order rate constants for transformation of the six fluoroquinolones by direct photolysis at 253.7 nm were determined for the pH 2-12 range. These parameters were deconvoluted to calculate specific molar absorptivity and fluence-based rate constants for cationic, zwitterionic, and anionic fluoroquinolone species. For a typical disinfection fluence of 40 mJ/cm(2), the apparent transformation efficiencies were inflated by 2-8% when fluoroquinolone products were not considered; moreover, the overall transformation efficiencies at 400 mJ/cm(2) varied by up to 40% depending on pH. The three product antibiotics, namely ciprofloxacin, sarafloxacin, and norfloxacin, were found to be equally or more potent than the parent fluoroquinolones using an Escherichia coli-based assay. UV treatment of a solution containing difloxacin was found to increase antimicrobial activity due to formation of sarafloxacin. These results highlight the importance of considering antibiotic-to-antibiotic transformations in UV-based processes.
authors.affiliation: University of Maryland Baltimore County , Department of Chemical, Biochemical and Environmental Engineering, 1000 Hilltop Circle, ECS 314 Baltimore, Maryland 21250, United States.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Snowberger
authors.affiliation: University of Maryland Baltimore County , Department of Chemical, Biochemical and Environmental Engineering, 1000 Hilltop Circle, ECS 314 Baltimore, Maryland 21250, United States.
authors.forename: Hollie
authors.initials: H
authors.lastname: Adejumo
authors.affiliation: University of Maryland Baltimore County , Department of Chemical, Biochemical and Environmental Engineering, 1000 Hilltop Circle, ECS 314 Baltimore, Maryland 21250, United States.
authors.forename: Ke
authors.initials: K
authors.lastname: He
authors.affiliation: University of Maryland Baltimore County , Department of Chemical, Biochemical and Environmental Engineering, 1000 Hilltop Circle, ECS 314 Baltimore, Maryland 21250, United States.
authors.forename: Kiranmayi P
authors.initials: KP
authors.lastname: Mangalgiri
authors.affiliation: University of Maryland Baltimore County , Department of Chemical, Biochemical and Environmental Engineering, 1000 Hilltop Circle, ECS 314 Baltimore, Maryland 21250, United States.
authors.forename: Mamatha
authors.initials: M
authors.lastname: Hopanna
authors.affiliation: University of Maryland Baltimore County , Department of Chemical, Biochemical and Environmental Engineering, 1000 Hilltop Circle, ECS 314 Baltimore, Maryland 21250, United States.
authors.forename: Ana Dulce
authors.initials: AD
authors.lastname: Soares
authors.affiliation: University of Maryland Baltimore County , Department of Chemical, Biochemical and Environmental Engineering, 1000 Hilltop Circle, ECS 314 Baltimore, Maryland 21250, United States.
authors.forename: Lee
authors.initials: L
authors.lastname: Blaney
mesh_terms: D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D024841:Fluoroquinolones; D007700:Kinetics; D009643:Norfloxacin; D010782:Photolysis
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D002939:Ciprofloxacin; D009643:Norfloxacin