Title : Identification of the human liver cytochrome P450 enzymes involved in the metabolism of zileuton (ABT-077) and its N-dehydroxylated metabolite, Abbott-66193.

Pub. Date : 1995 Oct

PMID : 8654206






3 Functional Relationships(s)
Download
Sentence
Compound Name
Protein Name
Organism
1 Results suggested that whereas the metabolism of zileuton and Abbott-66193 were mediated by the same CYP forms, the CYP forms responsible for hydroxylation (CYP1A2 and CYP2C9/10) were distinct from those involved in sulfoxidation (CYP3A > CYP2C9/10). zileuton cytochrome P450 family 2 subfamily C member 9 Homo sapiens
2 On the other hand, hydroxylation of the two compounds (zileuton, Km = 0.34 +/- 0.25 mM, Vmax = 17.8 +/- 5.58 pmol/min/mg; Abbott-66193,Km = 0.39 +/- 0.14 mM, Vmax = 1061 +/- 220 pmol/min/mg) was significantly correlated with 7-ethoxyresorufin O-deethylase (CYP1A2; r=0.652-0.762; p<0.01, N=11) and tolbutamide methyl hydroxylase (CYP2C9/10; r=0.863-0.935; p<0.01, N=10) activity in human liver microsome, and was inhibited (26-51%) by well-known CYP1A2 inhibitors (furafylline and alpha-naphthoflavone). zileuton cytochrome P450 family 2 subfamily C member 9 Homo sapiens
3 Abbott-66193 was a better substrate for CYP2C9/10, when compared with zileuton: 1) the effect of sulfaphenazole on hydroxylation in human liver microsomes was more pronounced for Abbott-66193 than zileuton (56% vs. 9% inhibition); and 2) the rate of Abbott-66193 hydroxylation by purified CYP2C9 was almost 30-fold greater than that of zilueton. Sulfaphenazole cytochrome P450 family 2 subfamily C member 9 Homo sapiens