title: In vitro glucuronidation kinetics of deoxynivalenol by human and animal microsomes and recombinant human UGT enzymes.
abstract: The mycotoxin deoxynivalenol (DON), formed by Fusarium species, is one of the most abundant mycotoxins contaminating food and feed worldwide. Upon ingestion, the majority of the toxin is excreted by humans and animal species as glucuronide conjugate. First in vitro data indicated that DON phase II metabolism is strongly species dependent. However, kinetic data on the in vitro metabolism as well as investigations on the specific enzymes responsible for DON glucuronidation in human are lacking. In the present study, the DON metabolism was investigated using human microsomal fractions and uridine-diphosphoglucuronyltransferases (UGTs) as well as liver microsomes from five animal species. Only two of the twelve tested human recombinant UGTs led to the formation of DON glucuronides with a different regiospecificity. UGT2B4 predominantly catalyzed the formation of DON-15-O-glucuronide (DON-15GlcA), while for UGT2B7 the DON-3-O-glucuronide (DON-3GlcA) metabolite prevailed. For human UGTs, liver, and intestinal microsomes, the glucuronidation activities were low. The estimated apparent intrinsic clearance (Clapp,int) for all human UGT as well as tissue homogenates was <1 mL/min mg protein. For the animal liver microsomes, moderate Clapp,int between 1.5 and 10 mL/min mg protein were calculated for carp, trout, and porcine liver. An elevated glucuronidation activity was detected for rat and bovine liver microsomes leading to Clapp,int between 20 and 80 mL/min mg protein. The obtained in vitro data points out that none of the animal models is suitable for estimating the human DON metabolism with respect to the metabolite pattern and formation rate.
authors.affiliation: Division of Food Analysis, BAM - Federal Institute for Materials Research and Testing, Richard-Willstätter-Straße 11, 12489, Berlin, Germany, maul@igzev.de.
authors.forename: Ronald
authors.initials: R
authors.lastname: Maul
authors.forename: Benedikt
authors.initials: B
authors.lastname: Warth
authors.forename: Nils Helge
authors.initials: NH
authors.lastname: Schebb
authors.forename: Rudolf
authors.initials: R
authors.lastname: Krska
authors.forename: Matthias
authors.initials: M
authors.lastname: Koch
authors.forename: Michael
authors.initials: M
authors.lastname: Sulyok
mesh_terms: D000818:Animals; D002347:Carps; D002417:Cattle; D002853:Chromatography, Liquid; D020719:Glucuronides / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D050217:Metabolic Detoxication, Phase II; D008862:Microsomes, Liver / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D013552:Swine; D053719:Tandem Mass Spectrometry; D014255:Trichothecenes / Q000378:metabolism* / Q000633:toxicity*; D014337:Trout
chemical_list: D020719:Glucuronides; D011994:Recombinant Proteins; D014255:Trichothecenes; D014453:Glucuronosyltransferase; C486404:UGT2B4 protein, human; C007262:deoxynivalenol