Carbonyl reduction of triadimefon by human and rodent 11β-hydroxysteroid dehydrogenase 1

Meyer, Arne and Vuorinen, Anna and Zielinska, Agnieszka E. and Da Cunha, Thierry and Strajhar, Petra and Lavery, Gareth G. and Schuster, Daniela and Odermatt, Alex. (2013) Carbonyl reduction of triadimefon by human and rodent 11β-hydroxysteroid dehydrogenase 1. Biochemical pharmacology, Vol. 85, H. 9. pp. 1370-1378.

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Official URL: http://edoc.unibas.ch/dok/A6194605

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11β-Hydroxysteroid dehydrogenase 1 (11β-HSD1) catalyzes the conversion of inactive 11-oxo glucocorticoids (endogenous cortisone, 11-dehydrocorticosterone and synthetic prednisone) to their potent 11β-hydroxyl forms (cortisol, corticosterone and prednisolone). Besides, 11β-HSD1 accepts several other substrates. Using rodent liver microsomes and the unspecific inhibitor glycyrrhetinic acid, it has been proposed earlier that 11β-HSD1 catalyzes the reversible conversion of the fungicide triadimefon to triadimenol. In the present study, recombinant human, rat and mouse enzymes together with a highly selective 11β-HSD1 inhibitor were applied to assess the role of 11β-HSD1 in the reduction of triadimefon and to uncover species-specific differences. To further demonstrate the role of 11β-HSD1 in the carbonyl reduction of triadimefon, microsomes from liver-specific 11β-HSD1-deficient mice were employed. Molecular docking was applied to investigate substrate binding. The results revealed important species differences and demonstrated the irreversible 11β-HSD1-dependent reduction of triadimefon. Human liver microsomes showed 4 and 8 times higher activity than rat and mouse liver microsomes. The apparent Vmax/Km of recombinant human 11β-HSD1 was 5 and 15 times higher than that of mouse and rat 11β-HSD1, respectively, indicating isoform-specific differences and different expression levels for the three species. Experiments using inhibitors and microsomes from 11β-HSD1-deficient mice indicated that 11β-HSD1 is the major if not only enzyme responsible for triadimenol formation. The IC50 values of triadimefon and triadimenol for cortisone reduction suggested that exposure to these xenobiotica unlikely impairs the 11β-HSD1-dependent glucocorticoid activation. However, elevated glucocorticoids during stress or upon pharmacological administration likely inhibit 11β-HSD1-dependent metabolism of triadimefon in humans.
Faculties and Departments:05 Faculty of Science > Departement Pharmazeutische Wissenschaften > Pharmazie > Molecular and Systems Toxicology (Odermatt)
UniBasel Contributors:Odermatt, Alex
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Pergamon Press
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:06 Dec 2013 09:35
Deposited On:06 Dec 2013 09:35

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