CYP2A6: a human coumarin 7-hydroxylase

Toxicology. 2000 Apr 3;144(1-3):139-47. doi: 10.1016/s0300-483x(99)00200-0.


Coumarin 7-hydroxylation is catalysed by a high-affinity CYP2A6 enzyme in human liver microsomes. CYP2A6 is the only enzyme catalysing this reaction and consequently the formation of 7-hydroxycoumarin can be used as 'an in vitro and in vivo probe' for CYP2A6. CYP2A6 is a major contributor to the oxidative metabolism of nicotine and cotinine, and it also contributes, to a larger or smaller extent, to the metabolism of a few pharmaceuticals (e.g. fadrozole), nitrosamines, other carcinogens (e.g. aflatoxin B1) and a number of coumarin-type alkaloids. CYP2A6 may be inducible by antiepileptic drugs and it is decreased in alcohol-induced severe liver cirrhosis. Several mutated or deleted CYP2A6 alleles have been characterized. Although CYP2A6 represent up to 15% of human microsomes P450 proteins, it is still one of the less well characterised cytochrome P450 enzymes.

Publication types

  • Review

MeSH terms

  • Anticoagulants / metabolism*
  • Aryl Hydrocarbon Hydroxylases*
  • Coumarins / metabolism*
  • Cytochrome P-450 CYP2A6
  • Cytochrome P-450 Enzyme Inhibitors
  • Cytochrome P-450 Enzyme System / biosynthesis
  • Cytochrome P-450 Enzyme System / metabolism*
  • Humans
  • Liver / enzymology
  • Mixed Function Oxygenases / antagonists & inhibitors
  • Mixed Function Oxygenases / biosynthesis
  • Mixed Function Oxygenases / metabolism*


  • Anticoagulants
  • Coumarins
  • Cytochrome P-450 Enzyme Inhibitors
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • Aryl Hydrocarbon Hydroxylases
  • CYP2A6 protein, human
  • Cytochrome P-450 CYP2A6