The inhibition study of human UDP-glucuronosyltransferases with cytochrome P450 selective substrates and inhibitors.
J Enzyme Inhib Med Chem
; 26(3): 386-93, 2011 Jun.
Article
em En
| MEDLINE
| ID: mdl-20939765
ABSTRACT
Human uridine-5'-diphosphoglucuronosyltransferases (UGTs) are the major phase II metabolizing enzymes. In the present study, five human UGTs (UGT1A1, 1A4, 1A6, 2B7, and 2B10) were individually expressed and used to examine the inhibition IC(50) values of 20 selective substrates and inhibitors of major cytochromes P450 (CYPs). The inhibition kinetics of UGT1A1 was also analyzed. The results showed that some compounds like α-naphthoflavone, paclitaxel, midazolam, cyclosporine A, and ketoconazole displayed strong inhibitions on UGT activities with their IC(50) values in a range of 4.1-26 µM. Especially, the IC(50) values were 4.1 ± 0.8 µM for ketoconazole in inhibiting UGT1A1-mediated ß-estradiol-3-glucuronidation, and 4.9 ± 0.3 µM for paclitaxel towards UGT1A4-mediated midazolam-N-glucuronidation. Additionally, the IC(50) values of bupropion, tolbutamide, and testosterone in inhibiting UGT-mediated metabolisms were similar with the K(m) values of respective CYPs. Some kinetic behaviours of UGTs were following Michaelis-Menten kinetics, while some were not.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Glucuronosiltransferase
/
Inibidores Enzimáticos
/
Inibidores das Enzimas do Citocromo P-450
Limite:
Humans
Idioma:
En
Revista:
J Enzyme Inhib Med Chem
Assunto da revista:
BIOQUIMICA
/
QUIMICA
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
China