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《Magnetic resonance in chemistry : MRC》2002,40(9):581-588
The configuration at C‐3 of the 3α‐ and 3β‐hydroxy metabolites of tibolone was studied by extensive application of one‐ and two‐dimensional 1H and 13C NMR spectroscopy combined with molecular modeling performed at the B3LYP/6–31G(d) level. Using HF and DFT GIAO methods, shielding tensors of the two molecules were computed; comparison of the calculated NMR chemical shifts with the experimental values revealed that the density functional methods produced the best results for assigning proton and carbon resonances. Although steroids are relatively large molecules, the present approach appears accurate enough to allow the determination of relative configurations by using calculated 13C resonances; the chemical shift of pairs of geminal α/β hydrogen atoms can also be established by using calculated 1H resonances. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Fabiana Fernandes de Santana e Silva Cardoso Isabela Costa César Iram Moreira Mundim Leonardo de Souza Teixeira Enikson Pontes da Silva Ricardo Rodrigues Bonfim Sandro Antônio Gomes Denys Pires Ferreira Aderimar Rogério Batista Lopes Helifas Duarte Pascoal Weidson Carlo de Souza Gerson Antônio Pianetti 《Biomedical chromatography : BMC》2013,27(11):1457-1462
A new method was developed for the quantitation of 3‐α‐hydroxy tibolone, in human plasma, after oral administration of a tablet formulation containing tibolone (2.5 mg). 3‐α‐Hydroxy tibolone was extracted by a liquid–liquid procedure, using cyproterone acetate as internal standard and chlorobutane as extraction solvent. After extraction, samples were submitted to a derivatization step with p‐toluenesulfonyl isocyanate. A mobile phase consisting of acetonitrile and water (72:28 v/v) was used and chromatographic separation was achieved using Agilent XDB C18 column (100 × 4.6 mm i.d.; 5 µm particle size), at 40°C. Mass spectrometric detection was performed using atmospheric pressure chemical ionization in negative mode for 3‐α‐hydroxy tibolone and in positive mode for cyproterone acetate. The fragmentation transitions were m/z 510.2 → m/z 170.1 and m/z 417.0 → m/z 357.1 for 3‐α‐hydroxy tibolone and cyproterone acetate, respectively. Calibration curves were constructed over the range 100–30,000 pg/mL and the method was shown to be specific, precise and accurate, with a mean recovery rate of 94.2% for 3‐α‐hydroxy tibolone. No matrix effect or carry‐over was detected in the samples. The validated method was applied in a pharmacokinetic study with a tibolone formulation in healthy female volunteers. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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