Human liver microsomal cytochrome P450 3A enzymes involved in thalidomide 5-hydroxylation and formation of a glutathione conjugate

Chem Res Toxicol. 2010 Jun 21;23(6):1018-24. doi: 10.1021/tx900367p.


(R)-Thalidomide was oxidized to 5-hydroxythalidomide and 5'-hydroxythalidomide by NADPH-fortified liver microsomes from humans and monkeys. (R)-Thalidomide was hydroxylated more efficiently than (S)-thalidomide. Recombinant human P450s 3A4, 3A5, and 3A7 and monkey P450s 3A8 and 3A5 (coexpressed with NADPH-P450 reductase in bacterial membranes) also catalyzed (R)-thalidomide 5-hydroxylation. Purified human P450s 2C19, 3A4, and 3A5 mediated (R)-thalidomide 5-hydroxylation at similar rates in reconstituted systems. P450 2C19 showed a rather nonsaturable substrate-velocity curve; however, P450s 3A4 and 3A5 showed sigmoidal curves. P450 also oxidized 5-hydroxythalidomide to an epoxide or dihydroxy compound. Liquid chromatography-mass spectrometry analysis revealed the formation of a glutathione conjugate from (R)- and (S)-5-hydroxythalidomide, catalyzed by liver microsomal P450s 3A4 and 3A5 in the presence of glutathione (assigned as a conjugate of 5-hydroxythalidomide formed on the phenyl ring). These results indicate that human P450s 3A4 and 3A5 mediate thalidomide 5-hydroxylation and further oxidation leading to a glutathione conjugate, which may be of relevance in the pharmacological and toxicological actions of thalidomide.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cytochrome P-450 CYP3A / metabolism*
  • Glutathione / metabolism*
  • Humans
  • Hydroxylation
  • Macaca fascicularis
  • Microsomes, Liver / enzymology*
  • Oxidation-Reduction
  • Rabbits
  • Swine
  • Thalidomide / metabolism*


  • Thalidomide
  • Cytochrome P-450 CYP3A
  • Glutathione