title: Examination of structurally selective derivatization of vitamin D(3) analogues by electrospray mass spectrometry.
abstract: The structural specificity of vitamin D derivatization by PTAD (4-phenyl-1,2,4-triazoline-3,5-dione) was probed using synthetic analogues and ion trap mass spectrometry. EB 1089, a vitamin D(3) analogue which contains a second site for Diels--Alder cycloaddition on its side-chain, allowed the examination of derivatization modes and comparisons of ion fragment structures. The origins of a PTAD-vitamin D(3) ion fragment, commonly used in metabolite characterization and quantitation of vitamin D(3) analogues (m/z 314), were established; ion trap mass spectrometry revealed that the PTAD comprises a portion of this diagnostic fragment, and is not lost by a retro-Diels--Alder step. Furthermore, the unique structure of the EB 1089 side-chain also permits facile determination of its side-chain metabolism. Use of PTAD derivatization and detection of metabolite-specific ion fragments identify hydroxylation at the end of the EB 1089 sidechain. It is believed that the results from these studies provide a clearer understanding of the mass spectrometry of triazolinedione derivatives, not only in the specific case of EB 1089, but also in their application to other vitamin D compounds.
authors.affiliation: The Barnett Institute and Department of Chemistry, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Weiskopf
authors.forename: P
authors.initials: P
authors.lastname: Vouros
authors.forename: J
authors.initials: J
authors.lastname: Cunniff
authors.forename: E
authors.initials: E
authors.lastname: Binderup
authors.forename: F
authors.initials: F
authors.lastname: Björkling
authors.forename: L
authors.initials: L
authors.lastname: Binderup
authors.forename: M C
authors.initials: MC
authors.lastname: White
authors.forename: G H
authors.initials: GH
authors.lastname: Posner
mesh_terms: D002117:Calcitriol / Q000031:analogs & derivatives* / Q000737:chemistry; D002762:Cholecalciferol / Q000737:chemistry*; D006900:Hydroxylation; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization; D014230:Triazoles / Q000737:chemistry
chemical_list: D014230:Triazoles; D002762:Cholecalciferol; C053540:4-phenyl-1,2,4-triazoline-3,5-dione; D002117:Calcitriol; C078903:seocalcitol