title: In vitro metabolism of 2-ethylhexyldiphenyl phosphate (EHDPHP) by human liver microsomes.
abstract: 2-ethylhexyl diphenyl phosphate (EHDPHP) is used as flame retardant and plasticizer additive in a variety of consumer products. Since EHDPHP is toxic to aquatic organisms and has been detected in environmental samples, concerns about human exposure and toxicity are emerging. With the aim of identifying human-specific metabolites, the biotransformation of EHDPHP was investigated using human liver microsomes. Using an in silico program (Meteor) for the prediction of metabolites, untargeted screening tools (agilent Mass Hunter) and a suitable analysis platform based on ultra-high performance liquid chromatography (UPLC) and quadrupole time-of-flight high resolution mass spectrometer (QTOF-MS), for the first time a wide variety of phases-I and II metabolites of EHDPHP were identified. Mono- and di-hydroxylated metabolites, keto metabolites, mixed keto and hydroxylated metabolites and diphenyl phosphate were the major phase-I metabolites of EHDPHP. Glucuronidated metabolites of phase-I metabolites of EHDPHP were also formed by human liver microsomes. Using these results, we propose a general metabolism pathway for EHDPHP in humans and a number of candidate biomarkers for assessing the human exposure to this ubiquitous phosphate flame retardant and plasticizer in future biomonitoring studies. Furthermore, we provide a template analytical approach based on the combination of untargeted and targeted screening and UPLC-QTOF-MS analysis suitable for use in future metabolism studies.
authors.affiliation: Toxicological Center, University of Antwerp, Universiteitsplein 1, Antwerp, Wilrijk 2610, Belgium; Institute for Environmental Studies (IVM), VU University, De Boelelaan 1087, Amsterdam 1081 HV, The Netherlands. Electronic address: a.m.ballesterosgomez@gmail.com.
authors.forename: Ana
authors.initials: A
authors.lastname: Ballesteros-Gómez
authors.affiliation: Toxicological Center, University of Antwerp, Universiteitsplein 1, Antwerp, Wilrijk 2610, Belgium.
authors.forename: Claudio A
authors.initials: CA
authors.lastname: Erratico
authors.affiliation: Toxicological Center, University of Antwerp, Universiteitsplein 1, Antwerp, Wilrijk 2610, Belgium.
authors.forename: Nele Van den
authors.initials: NV
authors.lastname: Eede
authors.affiliation: Toxicological Center, University of Antwerp, Universiteitsplein 1, Antwerp, Wilrijk 2610, Belgium.
authors.forename: Alin C
authors.initials: AC
authors.lastname: Ionas
authors.affiliation: Institute for Environmental Studies (IVM), VU University, De Boelelaan 1087, Amsterdam 1081 HV, The Netherlands.
authors.forename: Pim E G
authors.initials: PE
authors.lastname: Leonards
authors.affiliation: Toxicological Center, University of Antwerp, Universiteitsplein 1, Antwerp, Wilrijk 2610, Belgium.
authors.forename: Adrian
authors.initials: A
authors.lastname: Covaci
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005260:Female; D005411:Flame Retardants / Q000378:metabolism*; D020719:Glucuronides / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000378:metabolism; D006801:Humans; D006900:Hydroxylation; D008297:Male; D050216:Metabolic Detoxication, Phase I; D050217:Metabolic Detoxication, Phase II; D008862:Microsomes, Liver / Q000201:enzymology*; D010755:Organophosphates / Q000378:metabolism*; D010968:Plasticizers / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D015238:Sulfotransferases / Q000378:metabolism
chemical_list: D005411:Flame Retardants; D020719:Glucuronides; D010755:Organophosphates; D010968:Plasticizers; C018535:2-ethylhexyldiphenylphosphate; D014453:Glucuronosyltransferase; D015238:Sulfotransferases
keywords: 2-Ethylhexyldiphenyl phosphate; Human liver microsomes; In vitro; Mass spectrometry; Metabolism