title: Induction of cytochrome P4501A (CYP1A) by clotrimazole, a non-planar aromatic compound. Computational studies on structural features of clotrimazole and related imidazole derivatives.
abstract: The classical pathway for induction of cytochrome P4501A (CYP1A) by xenobiotics is ligand binding to the aryl hydrocarbon receptor (AhR). High-affinity AhR ligands are planar polyaromatic molecules such as the prototypic ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The present work investigated the ability of the imidazole derivative, clotrimazole [1-(2'chlorotrityl)imidazole, CLO], to induce CYP1A in cultured rainbow trout (Oncorhynchus mykiss) hepatocytes at the catalytic activity (determined as 7-ethoxyresorufin-O-deethylase, EROD) and at the transcriptional level. CLO resulted in a significant increase of hepatocyte EROD activity and CYP1A mRNA at a concentration of 1.56 microM. Computational studies on the molecular structure of CLO show that CLO is unlikely to take a planar conformation. Further indications that CLO does not behave like a planar AhR ligand come from the experimental observation that co-incubation of trout hepatocytes with CLO and the AhR antagonist, alpha-naphthoflavone (alpha-NF), did not result in an inhibition of CLO induction of CYP1A mRNA, whereas alpha-NF was able to inhibit CYP1A induction by the prototpyic, planar AhR ligand, beta-naphthoflavone. The experimental findings on CLO agree with previous results obtained for another non-planar imidazole derivative, 1-benzylimidazole (BIM). Further, computational studies showed that the non-planar imidazoles, BIM and CLO, are highly similar with respect to some electrostatic properties, namely the dipole moment and the molecular electrostatic potential (MEP). Overall our experimental and computational studies suggest that transcriptional activation of CYP1A by the imidazole derivatives CLO and BIM is mediated by a mechanism different to that of prototypic CYP1A inducers such as the planar AhR-ligands.
authors.affiliation: Department of Chemical Ecotoxicology, UFZ Center for Environmental Research, Permoserstr. 15, D-04318 Leipzig, Germany. jmnavas@inia.es
authors.forename: José María
authors.initials: JM
authors.lastname: Navas
authors.forename: Antonio
authors.initials: A
authors.lastname: Chana
authors.forename: Bernardo
authors.initials: B
authors.lastname: Herradón
authors.forename: Helmut
authors.initials: H
authors.lastname: Segner
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003022:Clotrimazole / Q000737:chemistry* / Q000494:pharmacology*; D019295:Computational Biology; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D008968:Molecular Conformation; D017686:Oncorhynchus mykiss; D011789:Quantum Theory; D012333:RNA, Messenger / Q000096:biosynthesis; D018336:Receptors, Aryl Hydrocarbon / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013329:Structure-Activity Relationship; D015262:Xenobiotics / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D007093:Imidazoles; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D015262:Xenobiotics; D003577:Cytochrome P-450 Enzyme System; D019363:Cytochrome P-450 CYP1A1; D003022:Clotrimazole