Influence of Some Novel N-Substituted Azoles and Pyridines on Rat Hepatic CYP3A Activity (original) (raw)
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INDUCTION OF CYP1A BY THE N-IMIDAZOLE DERIVATIVE, 1-BENZYLIMIDAZOLE
Environmental Toxicology and Chemistry, 2003
Xenobiotics can induce cytochrome P4501A (CYP1A) by ligand binding to the aryl hydrocarbon receptor (AhR). Typical AhR ligands are polycyclic aromatic compounds with planar molecular conformation. The present work investigated the ability of the N-imidazole derivative, 1-benzylimidazole (BIM), to induce CYP1A in rainbow trout hepatocytes. Benzylimidazole increased hepatocellular CYP1A catalytic activity (determined as 7-ethoxyresorufin-O-deethylase [EROD] activity) and CYP1A mRNA in a concentration-dependent way. Computational studies on the molecular structure of BIM indicated that the energetically most stable BIM conformer has the imidazole ring and the phenyl ring in different planes, i.e., does not take a planar conformation. This property of BIM does not agree with the structural requirements of a typical AhR ligand. In line with this observation, we found that the AhR antagonist, ␣-naphthoflavone (␣NF), was not able to inhibit BIM induction of EROD activity and CYP1A mRNA, although it inhibited the induction of CYP1A by the prototypic AhR ligand, -naphthoflavone (NF). The results suggest that transcriptional activation of CYP1A by the N-imidazole derivative, BIM, is not mediated through direct ligand binding to the AhR.
Induction of CYP2A5 by pyrazole and its derivatives in mouse primary hepatocytes
Archives of Toxicology, 1998
Mouse liver CYP2A5 is induced by several structurally unrelated compounds. In intact mouse liver, pyrazole (PYR) and 4-hydroxypyrazole (4-OH) induce selectively the expression of CYP2A5 while expression of other CYPs is decreased. In this study we exposed mouse primary hepatocytes to PYR, 4-OH, 4-methylpyrazole (4Me; 0.1±20 mM) and 4-iodopyrazole (4-I; 0.1± 5.0 mM). PYR and its derivatives increased coumarin 7-hydroxylase activity, with 4-1 and 4-OH being the strongest inducers, by 114-fold and 41-fold, respectively. However, only 4-1 treatment increased markedly the CYP2A5 protein content. CYP2B9/10-mediated pent-oxyresoru®n O-deethylase activity (PROD) was decreased by 80% by 4-Me and 4-1, and by 50% by 4-OH while PYR had no marked eect. PYR and 4-Me increased 2-to 3-fold the CYPA1/2-mediated ethoxyresoru®n O-deethylase activity (EROD) while 4-OH and 4-1 had no marked eect on this enzyme. The time of exposure markedly aected the inducibility of 4-OH such that induction was 7-fold stronger when it was added to the incubation medium 24 h after the isolation of hepatocytes compared to exposure 3 h after their isolation. Cimetidine prevented the induction of coumarin 7-hydroxylase activity by PYR and 4-OH by 46 and 74%, respectively indicating that their eects on the expression of CYP2A5 are, at least partly, mediated via their metabolites. The data demonstrate that the regulation of CYP2A5 is dierent from other monooxygenases and that the eects of pyrazole and its derivatives are dierent in vivo and in vitro. Also, the timing of exposure markedly aects the inducibility of 4-OH in hepatocytes.
Life Sciences, 2004
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-(2Vchlorotrityl)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 AM. 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, a-naphthoflavone (a-NF), did not result in an inhibition of CLO induction of CYP1A mRNA, whereas a-NF was able to inhibit CYP1A induction by the prototpyic, planar AhR ligand, h-naphthoflavone. The experimental findings on CLO agree with previous results obtained for another non-planar imidazole derivative, 1benzylimidazole (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 Life Sciences 76 www.elsevier.com/locate/lifescie 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.
Bioorganic & Medicinal Chemistry Letters, 1998
Pyrimidine analogs of the pyridinylimidazole class of CSBP/p38 kinase inhibitors were prepared in an effort to reduce the potent inhibition of hepatic cytochrome P450 observed for the pyridinyl compounds. The substitution of pyrimidin-4-yl, 2-methoxypyrimidin-4-yl, or 2-methylaminopyrimidin-4-yl for pyridin-4-yl effectively dissociates CSBP/p38 kinase from P450 inhibition for this series and furthermore achieves an increase in oral activity.
Chemical Research in Toxicology, 2000
Objective: 1,4-Dihydropyridine calcium antagonists such as nifedipine are potent vasodilators. It is now commonly agreed that the oxidation of 1,4dihydropyridine into pyridine, which is one of the main metabolic pathways, is catalysed by the cytochrome P450 (CYP) 3A4 isoform. In the present study, the inhibitory eects of 13 kinds of 1,4-dihydropyridine calcium antagonists clinically used in Japan on human CYP-isoform-dependent reactions were investigated to predict the drug interactions using microsomes from human B-lymphoblast cells expressing CYP. Results: The speci®c activities for human CYP isoforms included 7-ethoxyresor®n O-deethylation (CYP1A1), phenacetin O-deethylation (CYP1A2), coumarin 7-hydroxylation (CYP2A6), 7-benzyloxyresoru®n O-dealkylation (CYP2B6), S-warfarin 7-hydroxylation (CYP2C9), S-mephenytoin 4¢-hydroxylaion (CYP2C19), bufuralol 1¢-hydroxylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1), and testosterone 6b-hydroxylation (CYP3A4). Benidipine and amlodipine competitively inhibited the CYP1A1 activity. Nifedipine, nisoldipine and aranidipine competitively inhibited the CYP1A2 activity. No 1,4-dihydropyridie calcium antagonists used in this study inhibited the CYP2A6 activity. Barnidipine and amlodipine inhibited the CYP2B6 activity. Nicardipine, benidipine, manidipine and barnidipine competitively inhibited the CYP2C9 and CYP2D6 activities. Inhibition extent of the CYP2E1 activity by nifedipine and aranidipine were weak. Nicardipine, benidipine and barnidipine inhibited the CYP2C19 and CYP3A4 activities. Among the human CYP isoforms investigated, the inhibitory eects of 1,4dihydropyridine calcium antagonists were potent on human CYP1A2, CYP2B6, CYP2C9, CYP2C19 and CYP2D6 as well as CYP3A4. Furthermore, the isoform selectivity of inhibition by 1,4-dihydropyridine calcium antagonists was clari®ed. Conclusions: In consideration of the K i values obtained in the in vitro inhibition study and the concentration of 1,4-dihydropyridine calcium antagonists in human liver, the possibility of in vivo drug interactions of nicardipine and other drugs which are mainly metabolised by CYP2C9 and/or CYP3A4 was suggested. The inhibition of human CYP isoforms by 1,4-dihydropyridine calcium antagonists except nicardipine might be clinically insig-ni®cant.
Chemico-Biological Interactions, 1998
Primary human hepatocytes contain a full complement of human drug-metabolizing enzymes and therefore represent a relevant experimental system for the evaluation of pharmacokinetic drug-drug interaction potential in human. In this study, the cytochrome P450 (CYP) induction potential of pantoprazole (PAN) was evaluated and compared to two other proton pump inhibitors (PPIs), omeprazole (OM) and lansoprazole (LAN). Primary human hepatocytes from three donors were studied. The hepatocytes were cultured for 3 days, followed by treatment for 3 days with the PPIs at 2, 5 and 10 vM. Two other known CYP inducers, 3-methylcholanthrene at 1 vM and rifampin at 50 vM, were also evaluated. Induction potentials of these chemicals for CYP1A and CYP3A were evaluated by isozyme activity and isozyme content. 7-Ethoxyresorufin-O-deethylase and testosterone 6i-hydroxylase activities were used as endpoints for CYP1A and CYP3A, respectively. Isozyme protein contents of CYP1A and CYP3A were evaluated via Western blotting. The results showed that for CYP1A induction, the rank ordering in induction potential was consistently OM \ LAN\PAN. CYP3A induction by the PPI's were observed in two of the three hepatocyte cultures, with no apparent differences in induction potency for the three compounds. Our results on CYP1A induction suggest that PAN has a lower drug-drug interaction potential than OM and LAN.
Journal of Pharmacy and Pharmacology, 2003
Mebendazole is a benzimidazole anthelmintic widely used in veterinary and human therapy. Among benzimidazole derivatives, several drugs with inducing effect on cytochromes P450 can be found. However, the induction capacity of mebendazole on P450s has not been explored yet. In this study, the effects of mebendazole on P4501A activity was tested in primary cultures of rat hepatocytes and in human hepatoma HepG2 cell line. Two known P4501A inducers with benzimidazole structure, tiabendazole and omeprazole, were also included in the experiments with the aim of studying structure-induction relationships. After 24-, 48- and 72-h incubation of rat hepatocytes and HepG2 cells with drugs in various concentrations (0.1–100μm), enzyme activity associated with P4501A1/2 (EROD, MROD) was measured. In addition, the P4501A1/2 protein levels in both in-vitro systems were determined by Western-blotting. Mebendazole provoked a significant increase in P4501A1/2 protein expression and P4501A activity i...
Acta Poloniae Pharmaceutica - Drug Research, 2020
The aim of this study was to identify cytochrome P450 (CYP) isoforms that participate in the metabolism of some novel arylpiperazine derivatives developed by authors as well as their potency to inhibit reactions catalyzed by identified lead metabolizing enzyme. Such studies allow to predicting possible drug-drug interactions that might occur during co-administration of studied compounds with other drugs that are metabolized by an identified enzyme. The compounds were incubated in vitro together with the isolated CYP isoforms. After the incubation, samples were analyzed by liquid chromatography coupled with mass spectrometry. The results showed the main contribution of CYP3A4 isoform in biotransformation of the investigated derivatives. With CYP3A4 being the main CYP isoform responsible for the metabolism of arylpiperazine derivatives and at the same time being the main metabolizing enzyme for almost 50% of all drugs, a high chance of in vivo drug-drug interactions emerged. Therefore, IC 50 values were also determined using testosterone hydroxylation as a probe reaction, specific for CYP3A4. The resulting values ranged from 6.13 to 15.85 µM, which places studied derivatives as moderate or weak inhibitors of CYP3A4. Those results, combined with the conclusion that all of the arylpiperazine derivatives are also metabolized to some extent by other CYP isoforms (providing alternative metabolic pathways), result in a conclusion that studied arylpiperazines might be safe for co-administration with other CYP3A4 substrates.
Induction of Cyp450 enzymes by 4-thiazolidinone-based derivatives in 3T3-L1 cells in vitro
Naunyn-Schmiedeberg's Archives of Pharmacology, 2020
4-Thiazolidinones and related derivatives are regarded as privileged structures in medicinal chemistry and a source of new drug-like compounds. To date it is known that thiazolidinones are able to induce CYP1A1 activity in 3T3-L1 cells. Therefore, to extend the knowledge of the mechanism of thiazolidinones in the cell, four chemically synthesized heterocycles were tested on 3T3-L1 cells. The 3T3-L1 cells were exposed to Les-2194, Les-3640, Les-5935, and Les-6166. Our study showed that 1 μM βNF, Les-2194, and Les-6166 decreased the expression of Ahr mRNA. In turn, βNF, Les-2194, and Les-3640 increased the Cyp1a1 mRNA expression at the same time interval. On the other hand, Les-5935 was found to decrease the Cyp1a1 mRNA expression. Interestingly, the expression of Cyp1a2 mRNA was activated only by βNF and Les-2194. The expression of Cyp1b1 mRNA in the 3T3 cell line increased after the βNF and Les-2194 treatment but declined after the exposure to Les-5935 and Les-6166. Moreover, the Le...
Identifying a Selective Substrate and Inhibitor Pair for the Evaluation of CYP2J2 Activity
Drug Metabolism and Disposition, 2012
CYP2J2, an arachidonic acid epoxygenase, is recognized for its role in the first-pass metabolism of astemizole and ebastine. To fully assess the role of CYP2J2 in drug metabolism, a selective substrate and potent specific chemical inhibitor are essential. In this study, we report amiodarone 4-hydoxylation as a specific CYP2J2-catalyzed reaction with no CYP3A4, or other drug-metabolizing enzyme, involvement. Amiodarone 4-hydroxylation enabled the determination of liver relative activity factor and intersystem extrapolation factor for CYP2J2. Amiodarone 4-hydroxylation correlated with astemizole O-demethylation but not with CYP2J2 protein content in a sample of human liver microsomes. To identify a specific CYP2J2 inhibitor, 138 drugs were screened using terfenadine and astemizole as probe substrates with recombinant CYP2J2. Forty-two drugs inhibited CYP2J2 activity by >50% at 30 M, but inhibition was substrate-dependent. Of these, danazol was a potent inhibitor of both hydroxylation of terfenadine (IC 50 ؍ 77 nM) and O-demethylation of astemizole (K i ؍ 20 nM), and inhibition was mostly competitive. Danazol inhibited CYP2C9, CYP2C8, and CYP2D6 with IC 50 values of 1.44, 1.95, and 2.74 M, respectively. Amiodarone or astemizole were included in a sevenprobe cocktail for cytochrome P450 (P450) drug-interaction screening potential, and astemizole demonstrated a better profile because it did not appreciably interact with other P450 probes. Thus, danazol, amiodarone, and astemizole will facilitate the ability to determine the metabolic role of CYP2J2 in hepatic and extrahepatic tissues.