title: Degradation of the antibiotics norfloxacin and ciprofloxacin by a white-rot fungus and identification of degradation products.
abstract: More than 90% of the antibiotics ciprofloxacin (CIPRO) and norfloxacin (NOR) at 2 mg L(-1) were degraded by Trametes versicolor after 7 days of incubation in malt extract liquid medium. In in vitro assays with purified laccase (16.7 nkat mL(-1)), an extracellular enzyme excreted constitutively by this fungus, 16% of CIPRO was removed after 20 h. The addition of the laccase mediator 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt led to 97.7% and 33.7% degradation of CIPRO and NOR, respectively. Inhibition of CIPRO and NOR degradation by the cytochrome P450 inhibitor 1-aminobenzotriazole suggests that the P450 system also plays a role in the degradation of the two antibiotics. Transformation products of CIPRO and NOR were monitored at different incubation times by triple-quadrupole and quadrupole time-of-flight mass spectrometry, and can be assigned to three different reaction pathways: (i) oxidation of the piperazinyl substituent, (ii) monohydroxylation, and (iii) formation of dimeric products.
authors.affiliation: Department of Analytical Chemistry, University of the Basque Country, P.K. 644, 48080 Bilbao, Spain.
authors.forename: Ailette
authors.initials: A
authors.lastname: Prieto
authors.forename: Monika
authors.initials: M
authors.lastname: Möder
authors.forename: Rosario
authors.initials: R
authors.lastname: Rodil
authors.forename: Lorenz
authors.initials: L
authors.lastname: Adrian
authors.forename: Ernest
authors.initials: E
authors.lastname: Marco-Urrea
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology; D001673:Biodegradation, Environmental; D001709:Biotechnology / Q000379:methods; D001711:Biotransformation; D002853:Chromatography, Liquid / Q000379:methods; D002939:Ciprofloxacin / Q000302:isolation & purification*; D019281:Dimerization; D042845:Laccase / Q000737:chemistry / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D008956:Models, Chemical; D009643:Norfloxacin / Q000302:isolation & purification*; D010100:Oxygen / Q000737:chemistry; D053719:Tandem Mass Spectrometry / Q000379:methods; D013678:Technology, Pharmaceutical / Q000379:methods; D013997:Time Factors; D055454:Trametes / Q000378:metabolism*; D014230:Triazoles / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D014230:Triazoles; C033020:1-aminobenzotriazole; D002939:Ciprofloxacin; D042845:Laccase; D009643:Norfloxacin; D010100:Oxygen