Higher activity of polymorphic NAD(P)H:quinone oxidoreductase in liver cytosols from blacks compared to whites

Toxicol Lett. 2006 Jul 14;164(3):249-58. doi: 10.1016/j.toxlet.2006.01.004. Epub 2006 Feb 14.


In human liver, the two-electron reduction of quinone compounds, such as menadione is catalyzed by cytosolic carbonyl reductase (CBR) and NAD(P)H:quinone oxidoreductase (NQO1) activities. We assessed the relative contributions of CBR and NQO1 activities to the total menadione reducing capacity in liver cytosols from black (n=31) and white donors (n=63). Maximal menadione reductase activities did not differ between black (13.0+/-5.0 nmol/min mg), and white donors (11.4+/-6.6 nmol/min mg; p=0.208). In addition, both groups presented similar levels of CBR activities (CBR(blacks)=10.9+/-4.1 nmol/min mg) versus CBR(whites)=10.5+/-5.8 nmol/min mg; p=0.708). In contrast, blacks showed higher NQO1 activities (two-fold) than whites (NQO1(blacks)=2.1+/-3.0 nmol/min mg versus NQO1(whites)=0.9+/-1.6 nmol/min mg, p<0.01). To further explore this disparity, we tested whether NQO1 activity was associated with the common NQO1(*)2 genetic polymorphism by using paired DNA samples for genotyping. Cytosolic NQO1 activities differed significantly by NQO1 genotype status in whites (NQO1(whites[NQO1*1/*1])=1.3+/-1.7 nmol/min mg versus NQO1(whites[NQO1*1/*2+NQO1*2/*2])=0.5+/-0.7 nmol/min mg, p<0.01), but not in blacks (NQO1(blacks[NQO1*1/*1])=2.6+/-3.4 nmol/min mg versus NQO1(blacks[NQO1*1/*2])=1.1+/-1.2 nmol/min mg, p=0.134). Our findings pinpoint the presence of significant interethnic differences in polymorphic hepatic NQO1 activity.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Alcohol Oxidoreductases / genetics
  • Alcohol Oxidoreductases / metabolism
  • Aldehyde Reductase
  • Aldo-Keto Reductases
  • Black People / genetics*
  • Cytosol / enzymology*
  • Female
  • Genotype
  • Humans
  • Liver / cytology
  • Liver / enzymology*
  • Male
  • Middle Aged
  • NAD(P)H Dehydrogenase (Quinone) / genetics
  • NAD(P)H Dehydrogenase (Quinone) / metabolism*
  • Polymorphism, Genetic*
  • Vitamin K 3 / pharmacokinetics
  • White People / genetics*


  • Vitamin K 3
  • Alcohol Oxidoreductases
  • Aldo-Keto Reductases
  • Aldehyde Reductase
  • NAD(P)H Dehydrogenase (Quinone)
  • NQO1 protein, human