2007 Fiscal Year Final Research Report Summary
FLUORESCENT PROBES OF HUMAN CYTOCHROME P450 2E1
| Project/Area Number |
18590148
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Medical pharmacy
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| Research Institution | Nagoya City University |
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Principal Investigator |
SAEKI Ken-ichi Nagoya City University, Graduate School of Pharmaceutical Sciences, Instructor (60254306)
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| Project Period (FY) |
2006 – 2007
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| Keywords | fluorescent probe / cvtochrome P450 / selective substrate / halogen-substitution / selectivity / aza-oolvcvclic aromatic hydrocarbon |
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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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