title: Stable isotope gas chromatography-tandem mass spectrometry determination of aminoethylcysteine ketimine decarboxylated dimer in biological samples.
abstract: Aminoethylcysteine ketimine decarboxylated dimer (AECK-DD; systematic name: 1,2-3,4-5,6-7,8-octahydro-1,8a-diaza-4,6-dithiafluoren-9(8aH)-one) is a previously described metabolite of cysteamine that has been reported to be present in mammalian brain, urine, plasma, and cells in culture and vegetables and to possess potent antioxidative properties. Here, we describe a stable isotope gas chromatography-tandem mass spectrometry (GC-MS/MS) method for specific and sensitive determination of AECK-DD in biological samples. (13)C(2)-labeled AECK-DD was synthesized and used as the internal standard. Derivatization was carried out by N-pentafluorobenzylation with pentafluorobenzyl bromide in acetonitrile. Quantification was performed by selected reaction monitoring of the mass transitions m/z 328 to 268 for AECK-DD and m/z 330 to 270 for [(13)C(2)]AECK-DD in the electron capture negative ion chemical ionization mode. The procedure was systematically validated for human plasma and urine samples. AECK-DD was not detectable in human plasma above approximately 4nM but was present in urine samples of healthy humans at a maximal concentration of 46nM. AECK-DD was detectable in rat brain at very low levels of approximately 8pmol/g wet weight. Higher levels of AECK-DD were detected in mouse brain (∼1nmol/g wet weight). Among nine dietary vegetables evaluated, only shallots were found to contain trace amounts of AECK-DD (∼6.8pmol/g fresh tissue).
authors.affiliation: Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany. tsikas.dimitros@mh-hannover.de
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Tsikas
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Evans
authors.forename: Travis T
authors.initials: TT
authors.lastname: Denton
authors.forename: Anja
authors.initials: A
authors.lastname: Mitschke
authors.forename: Frank-Mathias
authors.initials: FM
authors.lastname: Gutzki
authors.forename: John T
authors.initials: JT
authors.lastname: Pinto
authors.forename: Tetyana
authors.initials: T
authors.lastname: Khomenko
authors.forename: Sandor
authors.initials: S
authors.lastname: Szabo
authors.forename: Arthur J L
authors.initials: AJ
authors.lastname: Cooper
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D019963:Clinical Chemistry Tests / Q000379:methods*; D003543:Cysteamine / Q000494:pharmacology; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods* / Q000592:standards; D006801:Humans; D008297:Male; D051379:Mice; D009025:Morpholines / Q000032:analysis* / Q000097:blood / Q000737:chemistry / Q000652:urine; D051381:Rats; D012015:Reference Standards; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods* / Q000592:standards; D014675:Vegetables / Q000737:chemistry
chemical_list: C086349:5,9a-dihydro-5-oxopyrrolo(2,1-c-3,4-b')dithiomorpholine; D009025:Morpholines; D003543:Cysteamine