Development of liquid chromatography-tandem mass spectrometry-based analytical assays for the determination of HIF stabilizers in preventive doping research.
Hypoxia-inducible factor (HIF) stabilizers increase blood haemoglobin levels after oral administration and their use in sports was recently banned by the World Anti-Doping Agency. For the support of analytical assay development, the metabolic fate of two model HIF stabilizers, based on the isoquinoline-3-carboxamide scaffold of the lead drug candidate FG-2216, was assessed by in vitro methods. The analytes were identified and characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive and negative ionization mode using an API 4000 Qtrap as well as an exactive high resolution-high accuracy MS. The model HIF stabilizer N-[(1-chloro-4-hydroxy-7-isopropoxy-isoquinolin-3-carbonyl)-amino]-acetic acid (1), was converted into 3 major phase I metabolites by hydroxylation, dealkylation, and dehydrogenation. The structures of the hydroxylated and the dealkylated metabolites were confirmed by LC-coupled nuclear magnetic resonance spectroscopy. Moreover, glucuronic acid conjugates of the active drug and one of the dealkylated phase I metabolite were identified. Hydroxylation of model compound 2 (N-[(1-chloro-4-hydroxy-isoquinolin-3-carbonyl)-amino]-acetic acid) yielded two metabolites, regioisomeric to the dealkylated product of 1. Mass spectral data of compounds 1 and 2, as well as a structure-related analogue were included into a multi-target analytical assay based on direct injection and LC-MS/MS analysis of human urine. The method was validated for quantitative purposes. In an approach of preventive doping research, more comprehensive screening methods applying precursor ion (m/z 166) and neutral loss (-10 Da) scans were developed, allowing for the detection of unknown metabolites and structurally analogous HIF stabilizers emerging from ongoing lead structure developments.
Institute of Biochemistry, Centre for Preventive Doping Research, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
Simon
S
Beuck
Wolfgang
W
Bornatsch
Andreas
A
Lagojda
Wilhelm
W
Schänzer
Mario
M
Thevis
D002853:Chromatography, Liquid / Q000379:methods; D004300:Doping in Sports; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism*; D007546:Isoquinolines / Q000032:analysis / Q000378:metabolism* / Q000652:urine; D009682:Magnetic Resonance Spectroscopy; D058573:Performance-Enhancing Substances / Q000032:analysis / Q000378:metabolism* / Q000652:urine; D012680:Sensitivity and Specificity; D015813:Substance Abuse Detection / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
D051793:Hypoxia-Inducible Factor 1; D007546:Isoquinolines; D058573:Performance-Enhancing Substances