| Budget Amount *help |
¥3,460,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥360,000)
Fiscal Year 2007: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2006: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Cytochrome P450 (CYP) 2E1 is a major CYP isoform expressed in human liver. Human CYP2E1 is responsible for activation of carcinogenic nitrosamines such as dimethyl- and diethylnitrosamines. Because human CYP2E1 has been reported to be inducible by alcohol intake, fasting, and diabetes, it is an important CYP isoform for the investigation of drug-drug interactions. We have previously reported that quinoline (Q) is metabolized to 3-hydroxyquinoline (3-OH-Q) by CYP2E1, and that 3-OH-Q could be determined by fluorescence analysis. In the present study, a total of 43 quinoline-related substrates, including aza-chrysens, benzoquinolines and quinolines, were metabolized by a combination of human liver microsomes (HLMs) and various recombinant human CYPs, and the fluorescent metabolites were determined by fluorescence monitoring (Ex = 355 nm and Em = 460 nm).The fluorescent intensities of the metabolites of aza-chrysens and benzoquinolines were not high enough to detect the CYP2E1 activity. Most of the Q derivatives were metabolized to highly fluorescent metabolites; especially the metabolites of 4-Cl, 5-Cl-, 7-Cl-, 4-Me-, 5,7-diCl-, 5,8-diC1l- and 6,8-diCl-Q showed high fluorescent intensities. It is suggested that 5-Cl-Q and 5,7-diCl-Q are the most selective fluorescent probes of CYP2E1. On the other hands, 4-Me-Q and 7-Cl-Q were metabolized by many recombinant CYPs. 5,8-diCl-Q and 6,8-diCl-Q were not selective to CYP2E1, but they showed high selectivity to CYP3A4. The results showed that the substituted position of chlorine (s) on the Q molecule may alter CYP isoform selectivity in metabolism of Q derivatives.
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