Comparative GC-MS based in vitro assays of 5α-reductase activity using rat liver S9 fraction

Su Hyeon Lee, Dong Hyoung Lee, Jeong Ae Lee, Won Yong Lee, Bong Chul Chung, Man Ho Choi

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8 Citations (Scopus)


5α-Dihydrotestosterone (DHT) is the primary active metabolite of testosterone, catalyzed by 5α-reductase (5αR) in the skin, prostate, and liver. In this study, the 5αR activity in rat liver S9 fraction in the presence of a NADPH-generating system was evaluated and compared by gas chromatography-mass spectrometry (GC-MS)-based in vitro assays. Testosterone and a 5αR inhibitor, finasteride, were added to the S9 fractions and incubated at 37oC for 1 h. Both testosterone and DHT were quantitatively measured and compared with two different GC-MS-based steroid profiling techniques. DHT was not detected by conventional GC-MS analysis in the absence of finasteride when the concentration of testosterone in the S9 fraction was less than 0.2 μM, whereas the isotope-dilution GC-MS (GC-IDMS) system was able to evaluate the 5αR activity. Because the S9 fraction contains more reactive enzymes and is easier to collect from tissues compared with a microsomal solution, the combination of the S9 fraction and GC-IDMS technique may be a promising assay for evaluating the 5αR activity in large-scale clinical studies.

Original languageEnglish
Pages (from-to)21-24
Number of pages4
JournalMass Spectrometry Letters
Issue number1
Publication statusPublished - 2012

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Spectroscopy


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