title: Study of tamoxifen urinary metabolites in rat by ultra-high-performance liquid chromatography time-of-flight mass spectrometry.
abstract: Tamoxifen (TMX) is a nonsteroidal estrogen antagonist drug used for the treatment of breast cancer. It is also included in the list of banned substances of the World Anti Doping Agency (WADA) prohibited in and out of competition. In this work, the excretion of urinary metabolites of TMX after a single therapeutic dose administration in rats has been studied using ultra-high-performance liquid chromatography electrospray time-of-flight mass spectrometry (UHPLC-TOFMS). A systematic strategy based on the search of typical biotransformations that a xenobiotic can undergo in living organisms, based on their corresponding molecular formula modification and accurate mass shifts, was applied for the identification of TMX metabolites. Prior to UHPLC-TOFMS analyses, a solid-phase extraction step with polymeric cartridges was applied to urine samples. Up to 38 TMX metabolites were detected. Additional collision induced dissociation (CID) MS/MS fragmentation was performed using UHPLC-QTOFMS. Compared with recent previous studies in human urine and plasma, new metabolites have been reported for the first time in urine. Metabolites identified in rat urine include the oxygen addition, owing to different possibilities for the hydroxylation of the rings in different positions (m/z 388.2271), the incorporation of two oxygen atoms (m/z 404.2220) (including dihydroxylated derivatives or alternatives such as epoxidation plus hydroxylation or N-oxidation and hydroxylation), epoxide formation or hydroxylation and dehydrogenation [m/z 386.2114 (+O -H2 )], hydroxylation of the ring accompanied by N-desmethylation (m/z 374.2115), combined hydroxylation and methoxylation (m/z 418.2377), desaturated TMX derivate (m/z 370.2165) and its N-desmethylated derivate (m/z 356.2009), the two latter modifications not previously being reported in urine. These findings confirm the usefulness of the proposed approach based on UHPLC-TOFMS.
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, 23071, Jaén, Spain.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Domínguez-Romero
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, 23071, Jaén, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: García-Reyes
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, 23071, Jaén, Spain.
authors.forename: Miriam
authors.initials: M
authors.lastname: Beneito-Cambra
authors.affiliation: Cellular Stress and Age Research Group. Department of Experimental Biology, University of Jaén, 23071, Jaén, Spain.
authors.forename: Rubén
authors.initials: R
authors.lastname: Martínez-Romero
authors.affiliation: Cellular Stress and Age Research Group. Department of Experimental Biology, University of Jaén, 23071, Jaén, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Martinez-Lara
authors.affiliation: Cellular Stress and Age Research Group. Department of Experimental Biology, University of Jaén, 23071, Jaén, Spain.
authors.forename: María L
authors.initials: ML
authors.lastname: Del Moral-Leal
authors.affiliation: Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, 23071, Jaén, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina-Díaz
mesh_terms: D000818:Animals; D018931:Antineoplastic Agents, Hormonal / Q000378:metabolism* / Q000652:urine*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D008297:Male; D017208:Rats, Wistar; D013629:Tamoxifen / Q000378:metabolism* / Q000652:urine*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen
keywords: liquid chromatography; mass spectrometry; metabolite; tamoxifen; urine