title: Detection and characterization of a new metabolite of 17alpha-methyltestosterone.
abstract: The misuse of the anabolic steroid methyltestosterone is currently routinely monitored in doping control laboratories by gas chromatography-mass spectrometry (GC-MS) of two of its metabolites: 17alpha-methyl-5beta-androstane-3alpha,17beta-diol and 17alpha-methyl-5alpha-androstane-3alpha,17beta-diol. Because of the absence of any easy ionizable moiety, these metabolites are poorly detectable using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). In this study, the metabolism of methyltestosterone has been reinvestigated by the use of a precursor ion scan method in LC-ESI-MS/MS. Two metabolites have been detected using this method. Both compounds have been confirmed in postadministration urine samples of an urokinase plasminogen activator-severe combined immunodeficiency (uPA-SCID) mouse with humanized liver and were characterized by LC-MS/MS and GC-MS using both quadrupole and time of flight analyzers. From the detailed study of the fragmentation, these metabolites were proposed to be epimethyltestosterone and a dehydrogenated compound. Epimethyltestosterone has previously been described as a minor metabolite, whereas the occurrence of the oxidized metabolite has not been reported. Comparison with the synthesized reference revealed that the structure of the dehydrogenated metabolite is 6-ene-epimethyltestosterone. A selected reaction monitoring method including three transitions for each metabolite has been developed and applied to samples from an excretion study and to samples declared positive after GC-MS analysis. 6-Ene-epimethyltestosterone was found in all samples, showing its applicability in the detection of methyltestosterone misuse.
authors.affiliation: DoCoLab, Ghent University, Department of Clinical Chemistry, Microbiology and Immunology, Zwijnaarde, Belgium. oscar.pozomendoza@gmail.com
authors.forename: Oscar J
authors.initials: OJ
authors.lastname: Pozo
authors.forename: Peter
authors.initials: P
authors.lastname: Van Eenoo
authors.forename: Koen
authors.initials: K
authors.lastname: Deventer
authors.forename: Leen
authors.initials: L
authors.lastname: Lootens
authors.forename: Wim
authors.initials: W
authors.lastname: Van Thuyne
authors.forename: Maria K
authors.initials: MK
authors.lastname: Parr
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Schänzer
authors.forename: Juan V
authors.initials: JV
authors.lastname: Sancho
authors.forename: Felix
authors.initials: F
authors.lastname: Hernández
authors.forename: Philip
authors.initials: P
authors.lastname: Meuleman
authors.forename: Geert
authors.initials: G
authors.lastname: Leroux-Roels
authors.forename: Frans T
authors.initials: FT
authors.lastname: Delbeke
mesh_terms: D000818:Animals; D004311:Double-Blind Method; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D008777:Methyltestosterone / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D016513:Mice, SCID; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D018183:Transplantation Chimera
chemical_list: D008777:Methyltestosterone