Metabolism of anabolic steroids by recombinant human cytochrome P450 enzymes. Gas chromatographic-mass spectrometric determination of metabolites

J Chromatogr B Biomed Sci Appl. 1999 Nov 26;735(1):73-83. doi: 10.1016/s0378-4347(99)00400-4.


Metabolism of steroid hormones with anabolic properties was studied in vitro using human recombinant CYP3A4, CYP2C9 and 2B6 enzymes. The enzyme formats used for CYP3A4 and CYP2C9 were insect cell microsomes expressing human CYP enzymes and purified recombinant human CYP enzymes in a reconstituted system. CYP3A4 enzyme formats incubated with anabolic steroids, testosterone, 17alpha-methyltestosterone, metandienone, boldenone and 4-chloro-1,2-dehydro-17alpha-methyltestosterone, produced 6beta-hydroxyl metabolites identified as trimethylsilyl (TMS)-ethers by a gas chromatography-mass spectrometry (GC-MS) method. When the same formats of CYP2C9 were incubated with the anabolic steroids, no 6beta-hydroxyl metabolites were formed. Human lymphoblast cell microsomes expressing human CYP2B6 incubated with the steroids investigated produced traces of 6beta-hydroxyl metabolites with testosterone and 17alpha-methyltestosterone only. We suggest that the electronic effects of the 3-keto-4-ene structural moiety contribute to the selectivity within the active site of CYP3A4 enzyme resulting in selective 6beta-hydroxylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anabolic Agents / metabolism*
  • Aryl Hydrocarbon Hydroxylases*
  • Binding Sites
  • Cytochrome P-450 CYP2B6
  • Cytochrome P-450 CYP2C9
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 Enzyme System / metabolism*
  • Gas Chromatography-Mass Spectrometry / methods*
  • Humans
  • Hydroxylation
  • Lymphocytes / ultrastructure
  • Methandrostenolone / metabolism
  • Methyltestosterone / metabolism
  • Microsomes / enzymology
  • Mixed Function Oxygenases / metabolism
  • Oxidoreductases, N-Demethylating / metabolism
  • Recombinant Proteins / metabolism
  • Steroid 16-alpha-Hydroxylase*
  • Steroid Hydroxylases / metabolism
  • Testosterone / analogs & derivatives
  • Testosterone / metabolism


  • Anabolic Agents
  • Recombinant Proteins
  • Testosterone
  • boldenone
  • Cytochrome P-450 Enzyme System
  • Methandrostenolone
  • Mixed Function Oxygenases
  • Steroid Hydroxylases
  • CYP2C9 protein, human
  • Cytochrome P-450 CYP2C9
  • Aryl Hydrocarbon Hydroxylases
  • CYP2B6 protein, human
  • CYP3A protein, human
  • Cytochrome P-450 CYP2B6
  • Cytochrome P-450 CYP3A
  • Steroid 16-alpha-Hydroxylase
  • CYP3A4 protein, human
  • Oxidoreductases, N-Demethylating
  • Methyltestosterone