N-GLUCURONIDATION OF THE PLATELET-DERIVED GROWTH FACTOR RECEPTOR TYROSINE KINASE INHIBITOR 6,7-(DIMETHOXY-2,4-DIHYDROINDENO[1,2-C]PYRAZOL-3-YL)-(3-FLUORO-PHENYL)-AMINE BY HUMAN UDP-GLUCURONOSYLTRANSFERASES
The potential cancer therapeutic agent, 6,7-(dimethoxy-2, 4-dihydroindeno[1,2-c]pyrazol-3-yl)-(3-fluoro-phenyl)-amine (JNJ-10198409), formed three N -glucuronides that were positively identified by liquid chromatography-tandem mass spectrometry and NMR as N -amine-glucuronide (Glu-A), 1- N -pyrazole...
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Published in | Drug metabolism and disposition Vol. 34; no. 5; pp. 748 - 755 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
American Society for Pharmacology and Experimental Therapeutics
01.05.2006
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Subjects | |
Online Access | Get full text |
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Summary: | The potential cancer therapeutic agent, 6,7-(dimethoxy-2, 4-dihydroindeno[1,2-c]pyrazol-3-yl)-(3-fluoro-phenyl)-amine (JNJ-10198409),
formed three N -glucuronides that were positively identified by liquid chromatography-tandem mass spectrometry and NMR as N -amine-glucuronide (Glu-A), 1- N -pyrazole-glucuronide (Glu-B), and 2- N -pyrazole-glucuronide (Glu-C). All three N -glucuronides were detected in rat liver microsomes, whereas only Glu-A and -B were found in monkey and human liver microsomes.
In contrast to common glucuronides, Glu-B was completely resistant to β-glucuronidase. Kinetic analyses revealed that glucuronidation
of JNJ-10198409 in human liver microsomes exhibited atypical kinetics that may be described by a two-site binding model. For
the high affinity binding, K m values were 1.2 and 5.0 μM, and V max values were 2002 and 2403 nmol min â1 mg â1 for Glu-A and Glu-B, respectively. Kinetic constants of low affinity binding were not determined due to low solubility of
the drug. Among the human UDP-glucuronosyltransferases (UGTs) tested, UGT1A9, 1A8, 1A7, and 1A4 were the most active isozymes
to produce Glu-A; for the formation of Glu-B, UGT1A9 was the most active enzyme, followed by UGT1A3, 1A7, and 1A4. Glucuronidation
of JNJ-10198409 by those UGT1A enzymes followed classic Michaelis-Menten kinetics. In contrast, no glucuronides were formed
by all UGT2B isozymes tested, including UGT2B4, 2B7, 2B15, and 2B17. Collectively, these results suggested that glucuronidation
of JNJ-10198409 in human liver microsomes is catalyzed by multiple UGT1A enzymes. Since UGT1A enzymes are widely expressed
in various tissues, it is anticipated that both hepatic and extrahepatic glucuronidation will likely contribute to the elimination
of the drug in humans. Additionally, conjugation at the nitrogens of the pyrazole ring represents a new structural moiety
for UGT1A-mediated reactions. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0090-9556 1521-009X |
DOI: | 10.1124/dmd.106.009274 |