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

Chowdhury G, Murayama N, Okada Y, Uno Y, Shimizu M, Shibata N, Guengerich FP, Yamazaki H
Chem Res Toxicol. 2010 23 (6): 1018-24

PMID: 20443640 · PMCID: PMC3843493 · 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.

MeSH Terms (11)

Animals Cytochrome P-450 CYP3A Glutathione Humans Hydroxylation Macaca fascicularis Microsomes, Liver Oxidation-Reduction Rabbits Swine Thalidomide

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