title: Metabolism of diclofenac in plants--hydroxylation is followed by glucose conjugation.
abstract: Pharmaceuticals from human or veterinary medication form a new class of micropollutants that poses a serious threat to our aquatic environment and its organisms. The intensively used nonsteroidal anti-inflammatory drug diclofenac is found in the environment worldwide due to its poor elimination during waste water treatment processes. In order to test phytoremediation as a tool for the removal of this drug from waste water, the uptake of the compound into plant tissues and its metabolic pathway was addressed using Hordeum vulgare (barley) and a hairy root cell culture of Armoracia rusticana (horse radish) as model species. Diclofenac is taken up by plants and undergoes rapid metabolization; already after 3h of exposure the drug and its metabolites could be detected in the plant tissues. Similar to its fate in mammalian cells the drug is activated in a phase I reaction resulting in the hydroxylated metabolite 4'OH-diclofenac which is conjugated subsequently in phase II to a glucopyranoside, a typical plant specific metabolite. After exposure to 10 and 100 μM diclofenac a concentration dependent formation of the hydroxylated metabolite was observed, while the formation of the phase II metabolite OH-diclofenac glucopyranoside was not positively affected by the higher concentration. To our knowledge this is the first time these two human painkiller metabolites are shown to occur in plant tissues.
authors.affiliation: Helmholtz Zentrum München, GmbH, German Research Center for Environmental Health, Research Unit Microbe Plant Interactions, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Huber
authors.forename: Bernadett
authors.initials: B
authors.lastname: Bartha
authors.forename: Peter
authors.initials: P
authors.lastname: Schröder
mesh_terms: D031215:Armoracia / Q000378:metabolism; D001673:Biodegradation, Environmental; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004008:Diclofenac / Q000302:isolation & purification / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D005959:Glucosidases / Q000378:metabolism; D016695:Glycosyltransferases / Q000378:metabolism; D001467:Hordeum / Q000378:metabolism; D006900:Hydroxylation; D013058:Mass Spectrometry; D008861:Microsomes / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology; D018517:Plant Roots / Q000201:enzymology / Q000378:metabolism; D010944:Plants / Q000378:metabolism*
chemical_list: D004008:Diclofenac; D003577:Cytochrome P-450 Enzyme System; D016695:Glycosyltransferases; D005959:Glucosidases; D005947:Glucose