Steroidal isomers with uniform mass spectra of their per-TMS derivatives: Synthesis of 17-hydroxyandrostan-3-ones, androst-1-, and -4-ene-3,17-diols
摘要:
In human sports doping control analysis most of the steroids are analyzed after enzymatic hydrolysis of the glucuronides as per-trimethylsilyl (TMS) derivatives applying gas chromatography-mass spectrometry (GC-MS). According to the recommendations of the World Anti-Doping Agency the identification of analytes should be based on retention time and on mass spectrometric characterization. This study shows that the bis-TMS derivatives of 16 specific C19 steroids, namely the stereoisomers of S xi-androst-l-ene-3 xi,17 xi-diol (8 isomers), androst-4-ene-3 xi,17 xi-diol (4 isomers), and 17 xi-hydroxy-5 xi-androstan-3-one (4 isomers), reveal very similar mass spectra. As a rule, when taking the retention times, which are provided as Kovac indices for all these isomers, into account, a restriction to two or three possible isomers is possible. Reliable identification should additionally include a comparison of the retention times of the analytes with the reference compounds measured concomitantly. In some cases standard addition may be appropriate.Due to the limited availability; the above mentioned isomers were synthesized by reduction of the corresponding alpha,beta-unsaturated oxo, steroids either with K-Selectride or by catalytic hydrogenation (Pd/C as catalyst). The products of the reactions were identified by means of nuclear magnetic resonance (NMR) characterization and by further reduction to the corresponding 5 xi-androstane-3 xi,17 xi-diols and GC-MS comparison with commercially available reference standards. (c) 2007 Elsevier Inc. All rights reserved.
A method for the fluorescent detection of a substance, the method comprising providing particles comprising a metal or a metal oxide core, wherein one or more optionally fluorescently tagged antibodies or human specific peptide nucleic acid (PNA) oligomers for binding to a substance is/are bound, directly or indirectly, to the surface of the metal or metal oxide; contacting a substrate, which may or may not have the substance on its surface, with the particles for a time sufficient to allow the antibody/PNA oligomer to bind with the substance; removing those particles which have not bound to the substrate; if the antibodies or PNA oligomers are not fluorescently tagged, contacting the substrate with one or more fluorophores that selectively bind with the antibody and/or substance, then optionally washing the substrate to remove unbound fluorophores; and illuminating the substrate with appropriate radiation to show the fluorophores on the substrate.
A variety of bone anabolic compounds are useful for maintaining and/or increasing bone mass, density, and/or strength in mammals. Preferred compounds enhance bone anabolic activity while minimizing or eliminating undesirable feminizing or masculinizing effects.