title: Resolution of catecholic tetrahydroisoquinoline enantiomers and the determination of R- and S-salsolinol in biological samples by gas chromatography-mass spectrometry.
abstract: Tetrahydroisoquinolines (TIQs) might be formed endogenously and can act centrally to promote a mechanism governing alcohol drinking behaviour. The possibility that biosynthesis occurs through a stereospecific enzymatic reaction is considered. Several TIQs were transformed into diastereomers by a two-step derivation with N-methyl-N-trimethylsilyltrifluoracetamide and R-(-)-2-phenylbutyrylic acid and were analyzed by gas chromatography-mass spectrometry (GC-MS). High resolution of the TIQ enantiomers was achieved. This method was applied to the quantification of the enantiomers of salsolinol (SAL) in urine and plasma of healthy humans. Deuterated SAL was used as the internal standard. SAL was extracted from biological material using phenyl-boronic phase cartridges and transformed into diastereomers. The sensitivity and specificity of the assay permit the determination of the enantiomeric composition of SAL in plasma and urine. The limit of quantification was found to be 100 pg/ml for each enantiomer. The described method has the advantage that optimal resolution of the SAL enantiomers without peak overlapping between analyte and other compounds can be achieved. Contrary to other findings, our GC-MS studies have demonstrated that endogenously formed SAL is racemic in plasma as well as in urine of healthy subjects.
authors.affiliation: Research Institute for Molecular Pharmacology, Berlin, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Haber
authors.forename: P
authors.initials: P
authors.lastname: Henklein
authors.forename: M
authors.initials: M
authors.lastname: Georgi
authors.forename: M F
authors.initials: MF
authors.lastname: Melzig
mesh_terms: D003903:Deuterium; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007202:Indicators and Reagents; D007546:Isoquinolines / Q000032:analysis* / Q000097:blood / Q000652:urine; D012680:Sensitivity and Specificity; D013237:Stereoisomerism
chemical_list: D007202:Indicators and Reagents; D007546:Isoquinolines; C036617:salsolinol; D003903:Deuterium