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Roy K, Roy PP. Exploring QSARs for Binding Affinity of Azoles with CYP2B and CYP3A Enzymes Using GFA and G/PLS Techniques. Chem Biol Drug Des 2008; 71:464-473. [DOI: 10.1111/j.1747-0285.2008.00658.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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2
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Hasselberg L, Westerberg S, Wassmur B, Celander MC. Ketoconazole, an antifungal imidazole, increases the sensitivity of rainbow trout to 17alpha-ethynylestradiol exposure. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2008; 86:256-264. [PMID: 18082278 DOI: 10.1016/j.aquatox.2007.11.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 11/06/2007] [Accepted: 11/07/2007] [Indexed: 05/25/2023]
Abstract
This study focuses on effects of two classes of xenobiotics, azole fungicides and xenoestrogens, both of which have been detected in the aquatic environment. We hypothesize that azoles and estrogenic compounds are metabolized by cytochrome P450 (CYP) enzymes, and in particular CYP1A and CYP3A, to more readily excreted metabolites. We exposed rainbow trout (Oncorhynchus mykiss) to two different pharmaceutical representatives of theses two classes, such as the imidazole ketoconazole and the synthetic estrogen analogue, 17alpha-ethynylestradiol (EE(2)). Juvenile rainbow trout were i.p. injected with a single low dose of EE(2) (2.5 microg/kg), alone or in combination with ketoconazole (100mg/kg). Hepatic microsomal CYP1A and CYP3A protein expressions were analyzed in Western blots using polyclonal antibodies (PAb) and enhanced cheminoluminescence. CYP1A activities were analyzed using the ethoxyresorufin-O-deethylase (EROD) assay and CYP3A activities were analyzed using the benzyloxy-4-[trifluoromethyl]-coumarin-O-debenzyloxylase (BFCOD) assay. Plasma vitellogenin (vtg) and sex steroid hormones (i.e. 17beta-estradiol, testosterone and 11-keto-testosterone) were analyzed using commercially available ELISA-kits. The vtg mRNA expression was analyzed using quantitative (Q)-PCR. The dose of EE(2) selected had little or no effect on the estrogen receptor (ER) mediated vtg induction. However, in combination with ketoconazole this threshold-dose of EE(2) resulted in significantly elevated plasma vtg levels, 6 days post injection. Exposure to ketoconazole resulted in up to nine-fold induction of CYP1A after 3 days. However, this nine-fold induction was not reflected on the CYP1A catalytic activity, where exposure to ketoconazole resulted only in a two-fold increase in activity. Ketoconazole increased CYP3A protein levels 1.5-fold and decreased BFCOD activities by 80% at days 3 and 6. Treatment with ketoconazole and EE(2) alone and in combination had no significant effect on sex steroid hormones, compared to vehicle-treated fish. This study demonstrates that exposure to ketoconazole compromises the function of key enzymes involved in metabolic clearance of xenobiotics and steroids, and increases the sensitivity to EE(2) exposure in juvenile rainbow trout.
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Affiliation(s)
- Linda Hasselberg
- Department of Zoophysiology, Göteborg University, Box 463, SE 405 30 Göteborg, Sweden
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3
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Casley WL, Ogrodowczyk C, Larocque L, Jaentschke B, LeBlanc-Westwood C, Menzies JA, Whitehouse L, Hefford MA, Aubin RA, Thorn CF, Whitehead AS, Li X. Cytotoxic doses of ketoconazole affect expression of a subset of hepatic genes. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2007; 70:1946-1955. [PMID: 17966066 DOI: 10.1080/15287390701551407] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Ketoconazole is a widely prescribed antifungal drug, which has also been investigated as an anticancer therapy in both clinical and pre-clinical settings. However, severe hepatic injuries were reported to be associated with the use of ketoconazole, even in patients routinely monitored for their liver functions. Several questions concerning ketoconazole-induced hepatic injury remain unanswered, including (1) does ketoconazole alter cytochrome P450 expression at the transcriptional level?, (2) what types of gene products responsible for cytotoxicity are induced by ketoconazole?, and (3) what role do the major metabolites of ketoconazole play in this pathophysiologic process? A mouse model was employed to investigate hepatic gene expression following hepatotoxic doses of ketoconazole. Hepatic gene expression was analyzed using a toxicogenomic microarray platform, which is comprised of cDNA probes generated from livers exposed to various hepatoxicants. These hepatoxicants fall into five well-studied toxicological categories: peroxisome proliferators, aryl hydrocarbon receptor agonists, noncoplanar polychlorinated biphenyls, inflammatory agents, and hypoxia-inducing agents. Nine genes encoding enzymes involved in Phase I metabolism and one Phase II enzyme (glutathione S-transferase) were found to be upregulated. Serum amyloid A (SAA1/2) and hepcidin were the only genes that were downregulated among the 2364 genes assessed. In vitro cytotoxicity and transcription analyses revealed that SAA and hepcidin are associated with the general toxicity of ketoconazole, and might be usefully explored as generalized surrogate markers of xenobiotic-induced hepatic injury. Finally, it was shown that the primary metabolite of ketoconazole (de-N-acetyl ketoconazole) is largely responsible for the hepatoxicity and the downregulation of SAA and hepcidin.
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Affiliation(s)
- William L Casley
- Center for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, Ottawa, Ontario, Canada
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4
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Konwick BJ, Garrison AW, Avants JK, Fisk AT. Bioaccumulation and biotransformation of chiral triazole fungicides in rainbow trout (Oncorhynchus mykiss). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2006; 80:372-81. [PMID: 17118468 DOI: 10.1016/j.aquatox.2006.10.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 10/09/2006] [Accepted: 10/11/2006] [Indexed: 05/12/2023]
Abstract
There are very little data on the bioaccumulation and biotransformation of current-use pesticides (CUPs) despite the fact that such data are critical in assessing their fate and potential toxic effects in aquatic organisms. To help address this issue, juvenile rainbow trout (Oncorhynchus mykiss) were exposed to dietary concentrations of a mixture of chiral triazole fungicides (bromuconazole, cyproconazole, metconazole, myclobutanil, penconazole, propiconazole, tebuconazole, tetraconazole, and triadimefon) and a chiral legacy pesticide [alpha-hexachlorocyclohexane (alpha-HCH)] to study the bioaccumulation and biotransformation of these CUPs. Fish accumulated all triazoles rapidly during the 8 day uptake phase, and was followed by rapid elimination, which was estimated by taking accelerated sampling times during the 16 day depuration period. Half-lives (t1/2s) and times to 95% elimination (t95s) ranged from 1.0 to 2.5 and 4.5 to 11.0 days, respectively. Chiral analysis suggested no significant selectivity in biotransformation for most of the compounds based on statistically unaltered enantiomer fractions (EFs) in the fish compared to food values; exceptions were a change in EF of myclobutanil and changes in diastereomer fractions (DFs) of propiconazole and cyproconazole. No biotransformation was observed for alpha-HCH based on consistent EFs in the fish throughout the experiment and a t1/2 (15.8 days) that fell within the 95% confidence interval of a log K(ow)-log t1/2 relationship developed for assessing biotransformation of organic contaminants. This relationship did show that biotransformation accounted for the majority (ranging from 59.9 to 90.4%) of the elimination for all triazoles, and that triazole compounds with oxygen and hydroxyl functional groups were more easily biotransformed. This research indicated that chiral analysis may potentially miss biotransformation of CUPs and other potential non-persistent organic contaminants and shows the utility of the log K(ow)-log t1/2 relationship as a mechanistic tool for quantifying biotransformation. Based on the rapid biotransformation of the triazoles, future research should focus on formation of metabolites and their fate and possible effects in the environment.
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Affiliation(s)
- Brad J Konwick
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, United States.
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5
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Somchit N, Wong CW, Zuraini A, Ahmad Bustamam A, Hasiah AH, Khairi HM, Sulaiman MR, Israf DA. Involvement of phenobarbital and SKF 525A in the hepatotoxicity of antifungal drugs itraconazole and fluconazole in rats. Drug Chem Toxicol 2006; 29:237-53. [PMID: 16777703 DOI: 10.1080/01480540600651535] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Itraconazole and fluconazole are potent wide spectrum antifungal drugs. Both of these drugs induce hepatotoxicity clinically. The mechanism underlying the hepatotoxicity is unknown. The purpose of this study was to investigate the role of phenobarbital (PB), an inducer of cytochrome P450 (CYP), and SKF 525A, an inhibitor of CYP, in the mechanism of hepatotoxicity induced by these two drugs in vivo. Rats were pretreated with PB (75 mg/kg for 4 days) prior to itraconazole or fluconazole dosing (20 and 200 mg/kg for 4 days). In the inhibition study, for 4 consecutive days, rats were pretreated with SKF 525A (50 mg/kg) or saline followed by itraconazole or fluconazole (20 and 200 mg/kg) Dose-dependent increases in plasma alanine aminotransferase (ALT), gamma-glutamyl transferase (gamma-GT), and alkaline phosphatase (ALP) activities and in liver weight were detected in rats receiving itraconazole treatment. Interestingly, pretreatment with PB prior to itraconazole reduced the ALT and gamma-GT activities and the liver weight of rats. No changes were observed in rats treated with fluconazole. Pretreatment with SKF 525A induced more severe hepatotoxicity for both itraconazole and fluconazole. CYP 3A activity was inhibited dose-dependently by itraconazole treatment. Itraconazole had no effects on the activity of CYP 1A and 2E. Fluconazole potently inhibited all three isoenzymes of CYP. PB plays a role in hepatoprotection to itraconazole-induced but not fluconazole-induced hepatotoxicity. SKF 525A enhanced the hepatotoxicity of both antifungal drugs in vivo. Therefore, it can be concluded that inhibition of CYP may play a key role in the mechanism of hepatotoxicity induced by itraconazole and fluconazole.
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Affiliation(s)
- N Somchit
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia.
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6
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Hasselberg L, Grøsvik BE, Goksøyr A, Celander MC. Interactions between xenoestrogens and ketoconazole on hepatic CYP1A and CYP3A, in juvenile Atlantic cod (Gadus morhua). COMPARATIVE HEPATOLOGY 2005; 4:2. [PMID: 15701172 PMCID: PMC549046 DOI: 10.1186/1476-5926-4-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Accepted: 02/08/2005] [Indexed: 01/22/2023]
Abstract
BACKGROUND: Xenoestrogens and antifungal azoles probably share a common route of metabolism, through hepatic cytochrome P450 (CYP) enzymes. Chemical interactions with metabolic pathways may affect clearance of both xenobiotics and endobiotics. This study was carried out to identify possible chemical interactions by those substances on CYP1A and CYP3A, in Atlantic cod liver. We investigated effects of two xenoestrogens (nonylphenol and ethynylestradiol) and of the model imidazole ketoconazole, alone and in combination. RESULTS: Treatment with ketoconazole resulted in 60% increase in CYP1A-mediated ethoxyresorufin-O-deethylase (EROD) activity. Treatment with nonylphenol resulted in 40% reduction of CYP1A activity. Combined exposure to ketoconazole and nonylphenol resulted in 70% induction of CYP1A activities and 93% increase in CYP1A protein levels. Ketoconazole and nonylphenol alone or in combination had no effect on CYP3A expression, as analyzed by western blots. However, 2-dimensional (2D) gel electrophoresis revealed the presence of two CYP3A-immunoreactive proteins, with a more basic isoform induced by ketoconazole. Treatment with ketoconazole and nonylphenol alone resulted in 54% and 35% reduction of the CYP3A-mediated benzyloxy-4-[trifluoromethyl]-coumarin-O-debenzyloxylase (BFCOD) activity. Combined exposure of ketoconazole and nonylphenol resulted in 98% decrease in CYP3A activity. This decrease was greater than the additive effect of each compound alone. In vitro studies revealed that ketoconazole was a potent non-competitive inhibitor of both CYP1A and CYP3A activities and that nonylphenol selectively non-competitively inhibited CYP1A activity. Treatment with ethynylestradiol resulted in 46% decrease in CYP3A activity and 22% decrease in protein expression in vivo. In vitro inhibition studies in liver microsomes showed that ethynylestradiol acted as a non-competitive inhibitor of CYP1A activity and as an uncompetitive inhibitor of CYP3A activity. CONCLUSIONS: Ketoconazole, nonylphenol and ethynylestradiol all interacted with CYP1A and CYP3A activities and protein expression in Atlantic cod. However, mechanisms of interactions on CYP1A and CYP3A differ between theses substances and combined exposure had different effects than exposure to single compounds. Thus, CYP1A and CYP3A mediated clearance may be impaired in situations of mixed exposure to those types of compounds.
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Affiliation(s)
- Linda Hasselberg
- Department of Zoophysiology, Göteborg University, Box 463, SE 405 30 Göteborg, Sweden
| | - Bjørn E Grøsvik
- Department of Molecular Biology, HIB, University of Bergen, N 5020 Bergen, Norway
| | - Anders Goksøyr
- Department of Molecular Biology, HIB, University of Bergen, N 5020 Bergen, Norway
- Biosense Laboratories AS, N-5008, Bergen, Norway
| | - Malin C Celander
- Department of Zoophysiology, Göteborg University, Box 463, SE 405 30 Göteborg, Sweden
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7
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Abstract
The nuclear pregnane X receptor (PXR; NR1I2) is an important component of the body's adaptive defense mechanism against toxic substances including foreign chemicals (xenobiotics). PXR is activated by a large number of endogenous and exogenous chemicals including steroids, antibiotics, antimycotics, bile acids, and the herbal antidepressant St. John's wort. Elucidation of the three-dimensional structure of the PXR ligand binding domain revealed that it has a large, spherical ligand binding cavity that allows it to interact with a wide range of hydrophobic chemicals. Thus, unlike other nuclear receptors that interact selectively with their physiological ligands, PXR serves as a generalized sensor of hydrophobic toxins. PXR binds as a heterodimer with the 9-cis retinoic acid receptor (NR2B) to DNA response elements in the regulatory regions of cytochrome P450 3A monooxygenase genes and a number of other genes involved in the metabolism and elimination of xenobiotics from the body. Although PXR evolved to protect the body, its activation by a variety of prescription drugs represents the molecular basis for an important class of harmful drug-drug interactions. Thus, assays that detect PXR activity will be useful in developing safer prescription drugs.
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MESH Headings
- Amino Acid Sequence
- Animals
- Aryl Hydrocarbon Hydroxylases/genetics
- Bile Acids and Salts/metabolism
- Binding Sites
- Cell Nucleus/chemistry
- Cloning, Molecular
- Cytochrome P-450 CYP3A
- DNA/metabolism
- Dimerization
- Gene Expression Regulation/drug effects
- Humans
- Molecular Sequence Data
- Molecular Structure
- Oxidoreductases, N-Demethylating/genetics
- Polymorphism, Genetic
- Pregnane X Receptor
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
- Receptors, Retinoic Acid/metabolism
- Receptors, Steroid/chemistry
- Receptors, Steroid/genetics
- Receptors, Steroid/physiology
- Response Elements
- Retinoid X Receptors
- Transcription Factors/metabolism
- Xenobiotics/metabolism
- Xenobiotics/pharmacology
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Affiliation(s)
- Steven A Kliewer
- Nuclear Receptor Discovery Research, GlaxoSmithKline, Research Triangle Park, North Carolina 27709, USA.
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8
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Abstract
The pregnane X receptor (PXR) is a promiscuous nuclear receptor that has evolved to protect the body from toxic chemicals. PXR is activated by a structurally diverse collection of xenobiotics, including several widely used prescription drugs. Various lipophilic compounds produced by the body, such as bile acids and steroids, also activate PXR. PXR stimulates the transcription of cytochrome P450 3A monooxygenases and other genes involved in the detoxification and elimination of these potentially harmful chemicals. Assays that detect PXR activation have important implications for the design of future drugs in two respects. On the one hand, PXR activation assays can be used to determine whether candidate drugs are likely to induce CYP3A gene expression and interact with other medicines. On the other hand, PXR agonists may prove useful in the treatment of diseases in which toxic metabolites accumulate, such as cholestatic liver disease.
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Affiliation(s)
- Bryan Goodwin
- Nuclear Receptor Systems Research, GlaxoSmithKline Research and Development, Research Triangle Park, NC 27709, USA.
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9
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Kobayashi Y, Suzuki M, Ohshiro N, Sunagawa T, Sasaki T, Oguro T, Tokuyama S, Yamamoto T, Yoshida T. Induction and inhibition of cytochrome P450 and drug-metabolizing enzymes by climbazole. Biol Pharm Bull 2002; 25:53-7. [PMID: 11824557 DOI: 10.1248/bpb.25.53] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To determine the effect of climbazole on hepatic microsomal cytochrome P450 (P450) and drug-metabolizing enzymes, four different P450 isoforms (CYP2B1, 3A2, 2E1, and 2C12) were examined in female Long-Evans rats. Treatment of rats with climbazole resulted in the induction of P450 content. Climbazole both induced and inhibited aminopyrine N-demethylase activity, but not erythromycin N-demethylase activity. Uridine 5'-phosphate (UDP)-glucuronosyl transferase and glutathione S-transferase activities were also increased with climbazole treatment. Immunoblot analyses revealed that climbazole induces CYP2B1 and CYP3A2 at the lower dose examined, but it failed to increase CYP2B1 at the higher dose. Northern blot analysis revealed that climbazole markedly increases P450 2B1 mRNA. These results indicate that climbazole induces and inhibits P450-dependent drug-metabolizing enzymes in vivo and may have the dose-differential effect on CYP2B1 in rat liver.
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Affiliation(s)
- Yasuna Kobayashi
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan
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10
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Somchit N, Hassim SM, Samsudin SH. Itraconazole- and fluconazole-induced toxicity in rat hepatocytes: a comparative in vitro study. Hum Exp Toxicol 2002; 21:43-8. [PMID: 12046723 DOI: 10.1191/0960327102ht208oa] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This current study was to investigate the in vitro cytotoxicity of rat hepatocytes induced by the antifungal drugs, itraconazole and fluconazole. Both antifungal drugs caused dose-dependent cytotoxicity. In vitro incubation of hepatocytes with itraconazole revealed significantly higher lactate dehydrogenase (LDH) leakage when compared to fluconazole. Phenobarbital pretreated hepatocytes contained significantly higher total cytochrome P450 content than the control hepatocytes. P450 content was reduced approximately 30% for both types of hepatocytes after 6 hours incubation. Interestingly, cytotoxicity of itraconazole was reduced significantly by phenobarbital pretreatment. Phenobarbital did not have any effect on the cytotoxicity induced by fluconazole. These results demonstrate the in vitro toxicity of hepatocytes induced by itraconazole and fluconazole that were expressed in a dose- and time-dependent manner. Phenobarbital plays a role in the cytoprotection of hepatocytes to itraconazole-induced but not fluconazole-induced cytotoxicity in vitro.
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Affiliation(s)
- N Somchit
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Selangor.
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11
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Kobayashi Y, Suzuki M, Ohshiro N, Sunagawa T, Sasaki T, Tokuyama S, Yamamoto T, Yoshida T. Climbazole is a new potent inducer of rat hepatic cytochrome P450. J Toxicol Sci 2001; 26:141-50. [PMID: 11552297 DOI: 10.2131/jts.26.141] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We examined the effect of climbazole on the induction of rat hepatic microsomal cytochrome P450 (P450), and compared the induction potency with other N-substituted azole drugs such as clorimazole. We found that climbazole is found to be a potent inducer of rat hepatic microsomal P450 as clorimazole. Induced level of P450 by climbazole was almost similar in extent to clorimazole when compared with other imidazole drugs in a dose- and time-dependent manner. Parallel to the increase in P450, climbazole increased aminopyrine and erythromycin N-demethylase, ethoxycoumarin O-deethylase, and androstenedione 16 beta- and 15 alpha/6 beta hydroxylase activities; however, clorimazole did not induce aminopyrine N-demethylase activity irrespective of its marked increase in P450 content. Immunoblot analyses revealed that climbazole induced CYP2B1, 3A2 and 4A1. The present findings indicate that climbazole is a new potent inducer of hepatic microsomal P450 and drug-metabolizing enzymes like clorimazole, but it may have some differential mechanism(s) for these enzymes' induction in rat liver.
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Affiliation(s)
- Y Kobayashi
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan
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12
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Bu-Abbas A, Clifford MN, Walker R, Ioannides C. Modulation of hepatic cytochrome P450 activity and carcinogen bioactivation by black and decaffeinated black tea. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 1999; 7:41-47. [PMID: 21781908 DOI: 10.1016/s1382-6689(98)00049-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/1998] [Revised: 11/25/1998] [Accepted: 11/30/1998] [Indexed: 05/31/2023]
Abstract
The principal objective of this study was to compare the ability of green, black and decaffeinated black tea to modulate hepatic expression of cytochromes P450 in the rat, and the consequences on the bioactivation of some food-borne carcinogens. Furthermore, these studies allow inferences to be drawn as to the contribution of caffeine and flavanols in the tea-mediated changes in cytochrome P450 expression. Black tea is prepared from fresh tea leaf following oxidation of flavanols by polyphenol oxidases and consequently has a low content of these compounds. All three types of tea enhanced lauric acid hydroxylation but in the case of decaffeinated black tea no statistical significance was attained. Green tea and black tea, but not decaffeinated black tea, stimulated the O-dealkylations of methoxy-, ethoxy- and pentoxy-resorufin indicating upregulation of CYP1A and CYP2B. Immunoblot analysis revealed that green and black tea, but not decaffeinated black tea, elevated the hepatic CYP1A2 apoprotein levels. Hepatic microsomes from green and black tea-treated rats, but not those from the decaffeinated black tea-treated rats, were more effective than controls in converting IQ into mutagenic species in the Ames test. It is concluded that flavanols are not responsible for the effects of tea on the cytochrome P450 system, but caffeine could account for the increase in CYP1A2 and the consequent increase in the bioactivation of IQ.
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Affiliation(s)
- A Bu-Abbas
- School of Biological Sciences, University of Surrey, Guildford, Surrey, GU2 5XH, UK
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13
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Abstract
The effect of methoxsalen, the inhibitor of the hepatic mixed function oxidase, on the expression of liver cytochrome P450s was examined in rats. Administration of methoxsalen to rats significantly increased the hepatic content of P450 and activities of microsomal ethoxyresorufin O-deethylase (EROD), methoxyresorufin O-demethylase (MROD), pentoxyresorufin O-dealkylase (PROD), a representative activity of P4501A1, P4501A2 and P4502B1/2, respectively, in a dose-dependent manner. In contrast, there was no effect on the P4502E1 catalyzed aniline hydroxylase. In the time-course experiment, methoxsalen exhibited a biphasic effect on EROD, MROD, and PROD activities, an initial inhibitory phase was followed by a phase of induction following a single treatment. Immunoblot analysis using anti-rat liver P4501A and P4502B revealed that increase in the apoprotein levels of P4501A1/2 and P4502B1/2 by methoxsalen was consistent with those in enzyme activity levels. Levels of mRNA of P4501A1/2 and P4502B1/2 were also increased by methoxsalen in Northern blot analysis. These results demonstrated that methoxsalen acts as an inducer of the hepatic microsomal mixed function oxidase; selective induction of P4501A and P4502B families involved increases in mRNA levels.
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Affiliation(s)
- J H Gwang
- Department of Environmental Science, Chosun University, Kwangju City, South Korea
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14
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Sabzevari O, Hatcher M, Kentish P, O'Sullivan M, Gibson GG. Bifonazole, but not the structurally-related clotrimazole, induces both peroxisome proliferation and members of the cytochrome P4504A sub-family in rat liver. Toxicology 1996; 106:19-26. [PMID: 8571391 DOI: 10.1016/0300-483x(95)03150-e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Male Wistar rats were treated with a low (150 mumol/kg) and a high (750 mumol/kg) dose of either clotrimazole of bifonazole. Bifonazole, but not clotrimazole, exhibited the characteristics of a peroxisome proliferator including hepatomegaly (increase in liver:body weight ratio), up to a 4-fold induction of lauric acid omega-hydroxylase activity and an 8-fold induction of palmitoyl-CoA oxidation by rat liver peroxisomes. This induction of enzyme activities was paralleled by increased protein levels as determined by immunochemical analysis for both liver microsomal cytochrome P4504A1 and the peroxisomal trifunctional protein of the beta-oxidation spiral. In contrast, clotrimazole did not increase protein levels of either cytochrome P4504A or the trifunctional protein. Western blot analyses demonstrated that bifonazole also induced P4502B1/2B2, P4503A and P4501A1, but not P4502E1. Clotrimazole induced a similar spectrum of P450s as determined by Western blotting with the exception that this azole was a marginal P4501A1 inducer under the conditions studied. Taken collectively, our data provides evidence that bifonazole is one of the increasingly recognised, non-carboxylate containing xenobiotics that induce both peroxisome proliferation and the cytochrome P4504A sub-family in rat liver.
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Affiliation(s)
- O Sabzevari
- University of Surrey, School of Biological Sciences, Guildford, UK
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15
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Sabzevari O, Hatcher M, O'Sullivan M, Kentish P, Gibson G. Comparative induction of cytochrome P4504A in rat hepatocyte culture by the peroxisome proliferators, bifonazole and clofibrate. Xenobiotica 1995; 25:395-403. [PMID: 7645305 DOI: 10.3109/00498259509061860] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
1. The influence of imidazole and triazole antifungal drugs on cytochrome P450 levels in male Wistar primary rat hepatocyte culture for 70 h has been investigated and compared with clofibrate. 2. Bifonazole, clotrimazole, geniconazole clofibrate induced total P450 in hepatocytes, whereas itraconazole, miconazole and UK-47,265 did not. 3. When the CYP4A subfamily was examined, only bifonazole and clofibrate induced CYP4A as assessed by both Western blot analysis and the 11- and 12-hydroxylation of lauric acid. 4. By analysis of concentration-response curves in hepatocyte culture, bifonazole was 160 and 40 times more potent than clofibrate for induction of the 11- and 12-hydroxylation of lauric acid respectively. 5. Taken collectively, our data have identified bifonazole as a relatively potent, non-carboxylate inducer of CYP4A and the mechanism of induction and specificity of this azole is discussed.
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Affiliation(s)
- O Sabzevari
- Molecular Toxicology Group, School of Biological Sciences, University of Surrey, Guildford, UK
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16
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Yoshida T, Kobayashi Y, Masuko T, Hashimoto Y, Kuroiwa Y. Differential effects of 3 dipyridyl isomers on hepatic microsomal cytochrome P450 and heme oxygenase in rats. Toxicol Lett 1995; 76:145-53. [PMID: 7725346 DOI: 10.1016/0378-4274(94)03208-o] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We compared the effects of 3 dipyridyl isomers, 2,2'-dipyridyl, 2,4'-dipyridyl and 4,4'-dipyridyl, on hepatic microsomal heme oxygenase and drug-metabolizing enzyme activities in male rats. 2,2'-Dipyridyl increased cytochrome P450 (P450) content at lower doses, but decreased with increasing dose levels. Immunoblot analysis revealed that 2,2'-dipyridyl did not induce both P450 1A1/2 and P450 2B1/2, in contrast to 2,4'- and 4,4'-dipyridyls, both of which were inducers of either P450 1A1/2 and/or P450 2B1/2. Some drug-metabolizing enzyme activities gradually declined with the increasing dose level of 2,2'-dipyridyl. 2,2'-Dipyridyl was able to induce hepatic microsomal heme oxygenase in a dose-dependent manner, but 2,4'- and 4,4'-dipyridyls did not, even at the highest dose (0.80 mmol/kg) examined. Treatment of rats with 2,2'-dipyridyl resulted in the increase of glutathione (GSH) content in a dose-dependent manner, but not 4-substituted isomers. A time course study with 2,2'-dipyridyl revealed that it produced a significant decrease in hepatic GSH content at early time periods (2-6 h) after its administration with an inverse increase in heme oxygenase activity. The present investigation has revealed that in contrast to the induction of P450 by 4-substituted dipyridyl compounds, 2,2'-dipyridyl is a novel inducer of hepatic microsomal heme oxygenase, together with the change in hepatic GSH content. This study would provide information on the differential effects of simple dipyridyl isomers on hepatic enzymes involved in heme and drug metabolism.
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Affiliation(s)
- T Yoshida
- Department of Biochemical Toxicology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan
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17
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Bensoussan C, Delaforge M, Mansuy D. Particular ability of cytochromes P450 3A to form inhibitory P450-iron-metabolite complexes upon metabolic oxidation of aminodrugs. Biochem Pharmacol 1995; 49:591-602. [PMID: 7887973 DOI: 10.1016/0006-2952(94)00477-4] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The ability of 21 drugs containing an amine function to form inhibitory P450-iron-metabolite complexes absorbing around 455 nm was studied on liver microsomes from rats treated with various P450 inducers. These drugs belong to different chemical and therapeutic series and exhibit very different structures. In the case of eight compounds (diltiazem, lidocaine, imipramine, SKF 525A, fluoxetine, L-alpha-acetylmethadol, methadol and desmethyltamoxifen) whose oxidation by microsomes from rats treated with several inducers was studied, only dexamethasone (DEX)-treated rat microsomes and, to a lesser extent, phenobarbital (PB)-treated rat microsomes, were able to give significant amounts of 455 nm absorbing complexes. Ten of the 21 compounds studied gave such complexes with DEX-treated rat microsomes, while only three compounds gave complexes (in low amounts) with PB-treated rat microsomes only. For all compounds leading to complexes both with DEX- and PB-treated rat microsomes, much higher amounts of complexes were obtained with DEX-treated rat microsomes. DEX-treated rat microsomes also led to the most intense type I spectral interactions with most of the compounds studied, and very often exhibited the highest N-dealkylation activities towards the tertiary or secondary amine function of the drugs used. A few exceptions aside, there generally exists a qualitative relationship between the ability of P450 3As, induced by DEX, to bind and N-dealkylate amino compounds and their propensity to lead to 455 nm absorbing complexes. This was confirmed by in vivo experiments showing that rats treated with diltiazem, tamoxifen or imipramine accumulated large amounts of 455 nm absorbing complexes in their liver only after pretreatment with DEX and, to a lesser extent, with PB. This particular ability of P450 3As to oxidize amino drugs with formation of inhibitory P450-metabolite complexes could be of great importance for the appearance of drug interactions in man.
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Affiliation(s)
- C Bensoussan
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université René Descartes, Paris, France
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18
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Franklin MR. Induction of rat liver drug-metabolizing enzymes by heterocycle-containing mono-, di-, tri- and tetra-arylmethanes. Biochem Pharmacol 1993; 46:683-9. [PMID: 8363642 DOI: 10.1016/0006-2952(93)90555-b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effect of a nitrogen heterocycle constituent on the ability of arylmethanes to induce phase I and phase II drug-metabolizing enzymes has been examined. Rats were treated with tetra-, tri-, di- or monoarylmethane compounds daily for 3 days at a dose of 75 mg/kg. Induction of UDP-glucuronosyltransferase (morphine) activity was seen with twelve of the eighteen compounds investigated, and for three compounds it occurred independent of any induction of cytochrome P450. Induction of glutathione S-transferase activity was seen with ten of the compounds and was generally paralleled by changes in overall cytochrome P450 concentration and in both pentoxyresorufin and erythromycin dealkylase activities. Major induction of ethoxyresorufin deethylase activity was only apparent with two diarylmethanes that contained a 1-substituted imidazole moiety. UDP-glucuronosyltransferase (1-naphthol) activity was coinduced by these two compounds. A third compound, diphenyl-4-pyridylmethane, induced UDP-glucuronosyltransferase (1-naphthol) activity without increasing ethoxyresorufin deethylase activity. Cytosolic sulfotransferase activity was not induced by the administration of any compound in this study. Among arylmethane derivatives, the presence of two aryl groups appeared to be a minimum requirement for induction of drug-metabolizing enzymes. If one of the aryl groups was not a heterocycle, or if the nitrogen atom of the heterocycle was sterically hindered, major induction of cytochrome P450 did not occur. With triarylmethanes, induction was independent of whether the heterocycle was imidazole, pyridine or pyrimidine.
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Affiliation(s)
- M R Franklin
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City 84112
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19
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Delaforge M, Servent D, Wirsta P, Ducrocq C, Mansuy D, Lenfant M. Particular ability of cytochrome P-450 CYP3A to reduce glyceryl trinitrate in rat liver microsomes: subsequent formation of nitric oxide. Chem Biol Interact 1993; 86:103-17. [PMID: 8448809 DOI: 10.1016/0009-2797(93)90115-f] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Glyceryl trinitrate was denitrated in rat hepatic subcellular fractions, with formation of glyceryl dinitrates and glyceryl mononitrates. Among differently treated-rat liver microsomes, the highest microsomal activity was obtained under anaerobic conditions with microsomal preparations from dexamethasone-treated rats and NADPH. The reaction was inhibited by O2, CO, miconazole, dihydroergotamine and troleandomycin showing that it was catalyzed by cytochrome P-450 CYP3A isoforms. The formation of a transient cytochrome P-450 Fe(II)-NO complex during this reaction was shown by visible spectroscopy. The cytosolic activity was shown to be dependent on glutathione and glutathione transferase and was not inhibited by dioxygen. In the hepatic 9000 x g supernatant containing both NADPH and cytochrome P-450 and glutathione and glutathione transferase, the cytochrome P-450-dependent reaction accounts for 30-40% of the total denitration activity observed under anaerobic conditions, using 100 microM GTN.
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Affiliation(s)
- M Delaforge
- Université René Descartes URA 400 CNRS, Paris, France
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20
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Ioannides C, Ayrton AD, Lewis DF, Walker R. Extrapolation of in vitro antimutagenicity to the in vivo situation: the case for anthraflavic acid. BASIC LIFE SCIENCES 1993; 61:103-10. [PMID: 8304922 DOI: 10.1007/978-1-4615-2984-2_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- C Ioannides
- Division of Toxicology, School of Biological Sciences, University of Surrey, Guildford, United Kingdom
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21
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Antignac E, Fakuhara M, Kimura M, Ushio F. Clotrimazole-induced modulation of hepatic cytochrome P450 enzymes in Syrian and Chinese hamsters. Biochem Pharmacol 1992; 44:2266-70. [PMID: 1472091 DOI: 10.1016/0006-2952(92)90357-o] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Clotrimazole, an imidazole antifungal drug, is known to induce cytochrome P450 isozymes of the P450IIIA and P450IIB subfamilies in rats. This agent modulated hepatic cytochrome P450 enzymes differently in golden Syrian and Chinese hamsters and also in hamsters and rats. Clotrimazole at a daily intraperitoneal dose of 100 mg/kg for three days increased the amount of cytochrome P450 in the livers of the two hamster strains. In Syrian hamsters, clotrimazole significantly induced the activities of 7-pentoxyresorufin O-dealkylase, coumarin 7-hydroxylase, benzphetamine N-demethylase and testosterone 15 alpha- and 16 alpha-hydroxylases, but reduced those of testosterone 15 beta-, 7 alpha-, 6 beta-, 2 alpha- and 2 beta-hydroxylases. In Chinese hamsters, clotrimazole markedly stimulated the activities of coumarin 7-hydroxylase and testosterone 15 alpha, 16 alpha- and 2 alpha-hydroxylases as well as the formation of androstenedione. Western blot analysis revealed that clotrimazole treatment induced mainly cytochrome P450 isozymes immunorelated to the P450IIB and P450IIA subfamilies in Syrian hamsters and isozymes immunorelated to the P450IIA subfamily in Chinese hamsters. In contrast, in both hamster strains, clotrimazole did not induce the isozymes corresponding to the P450IIIA subfamily.
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Affiliation(s)
- E Antignac
- Department of Pharmaceutical Sciences, Institute of Public Health, Tokyo, Japan
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22
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Kobayashi Y, Matsuura Y, Kotani E, Iio T, Fukuda T, Aoyagi T, Tobinaga S, Yoshida T, Kuroiwa Y. Induction of hepatic microsomal cytochrome P450 and drug-metabolizing enzymes by 4-benzylpyridine and its structurally related compounds in rats. Dose- and sex-related differential induction of cytochrome P450 species. Biochem Pharmacol 1992; 43:2151-9. [PMID: 1599503 DOI: 10.1016/0006-2952(92)90174-h] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We examined the abilities of 4-, 3- and 2-benzylpyridine and 4-tert-butylpyridine to induce hepatic microsomal cytochrome P450 and drug-metabolizing enzymes in male and female rats in order to define the effects of pyridine-containing compounds on drug metabolism. 4-Benzylpyridine (0.4 mmol/kg, for 2 consecutive days) induced total cytochrome P450 to about three times that of the controls at 24 hr, and its inducing effect was sustained for 120 hr after the treatment in male and female rats. 4-Benzylpyridine was a more potent inducer of cytochrome P450 than 3- and 2-benzylpyridine, which induced the cytochrome to 71.4 and 43.9%, respectively, of that produced by the 4-substituted isomer. 4-tert-Butylpyridine also induced cytochrome P450. Immunoblot analysis revealed that a single treatment of male rats with 4-benzylpyridine at doses ranging from 0.05 to 0.80 mmol/kg induced cytochrome P450b/e and caused a maximum increase in the level of the isozyme at the 0.2 mmol/kg dose. 4-Benzylpyridine at doses from 0.40 to 0.80 mmol/kg also induced cytochrome P450c/d in male rats. In female rats, 4-benzylpyridine induced cytochrome P450b at doses ranging from 0.1 to 0.80 mmol/kg and produced a maximum increase in the level of this isozyme at 0.40 to 0.60 mmol/kg. Induction of cytochrome P450c/d by 4-benzylpyridine in female rats was observed at a dose of 0.20 mmol/kg, and the magnitude of the induction of the isozyme was increased in a dose-dependent manner. Both 3- and 2-benzylpyridine induced cytochrome P450b/e and/or c/d depending on the increase of total cytochrome P450 without changing the induction patterns of the isozymes. 4-tert-Butylpyridine induced cytochrome P450b at doses ranging from 0.20 to 0.60 mmol/kg and slightly induced P450c/d at doses ranging from 0.10 to 0.40 mmol/kg in male rats. These results and our previous report (Matsuura et al., Biochem Pharmacol 41: 1949-1956, 1991) clearly show that the pyridine compounds having lipophilic groups at the 4- or 3-position of the ring could be inducers of cytochrome P450. The present results also revealed that 4-benzylpyridine shows dose- and sex-related differences in the induction of cytochrome P450b/e and c/d in rats.
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Affiliation(s)
- Y Kobayashi
- Showa College of Pharmaceutical Sciences, Tokyo, Japan
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23
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Franklin MR. Drug metabolizing enzyme induction by simple diaryl pyridines; 2-substituted isomers selectively increase only conjugation enzyme activities, 4-substituted isomers also induce cytochrome P450. Toxicol Appl Pharmacol 1991; 111:24-32. [PMID: 1949033 DOI: 10.1016/0041-008x(91)90130-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Pyridine derivatives bearing aryl containing substitutions at the 2- and 4-position were administered to male rats, daily, for 3 days at 75 mg/kg. All five 2-substituted pyridines investigated increased rat hepatic UDP-glucuronosyltransferase activities toward three aglycones (morphine, p-nitrophenol, and 1-naphthol) without inducing cytochrome P450. Two of the 4-substituted pyridines investigated (4,4'-dipyridyl, 4-benzylpyridine) significantly induced cytochrome P450. UDP-glucuronosyl-transferase activity by the 4-substituted pyridines was increased to a much lesser extent than seen for the equivalent 2-isomers. The two 4-substituted pyridines eliciting induction of cytochrome P450 were also the only 4-isomers which increased cytosolic glutathione-S-transferase activity, but three 2-substituted pyridines (2-benzoylpyridine, 2-benzylpyridine, and trans-1,2-bis(2-pyridyl)ethylene) increased this activity in the absence of cytochrome P450 induction. No compound investigated induced cytosolic sulfotransferase activity. Diaryl compounds lacking a heterocyclic ring did not increase any of the investigated drug metabolizing enzyme activities. For simple diarylpyridines, the position of substitution on the pyridine ring rather than the nature of the substituent appears to be a major determinant for selective induction of UDP-glucuronosyltransferases without concurrent increases in cytochrome P450. The 2-substituted pyridines were consistently selective inducers of only Phase II or conjugation enzymes. The 4-substituted pyridines included derivatives that could selectively induce Phase II and nonselectively induce both Phase I and Phase II and one derivative that induced neither.
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Affiliation(s)
- M R Franklin
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City 84112
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24
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Gleizes C, Eeckhoutte C, Pineau T, Alvinerie M, Galtier P. Inducing effect of oxfendazole on cytochrome P450IA2 in rabbit liver. Consequences on cytochrome P450 dependent monooxygenases. Biochem Pharmacol 1991; 41:1813-20. [PMID: 2039538 DOI: 10.1016/0006-2952(91)90119-p] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Male New Zealand rabbits were dosed with either 0.9, 4.5 or 22.5 mg/kg/day of oxfendazole by gastric intubation for 10 days. Oxfendazole administered at the therapeutic dose (4.5 mg/kg) and at the highest dose (22.5 mg/kg) increased 1.54- and 2.36-fold the total liver microsomal cytochrome P450 and more particularly the isoenzyme P450IA2 (95 and 184% increases) as demonstrated by western blotting. Increases in ethoxyresorufin O-deethylation and hydroxylations of benzopyrene and acetanilide occurred in livers of the same animals without any change in N-demethylation of aminopyrine, benzphetamine or erythromycin. Because of the unchanged level of mRNA specific to cytochrome P450IA2, as shown by northern blot analysis of poly mRNA, an enzyme stabilization rather than a transcriptional activation of IA2 genes should be involved in the P450IA2 regulation mechanisms. Oxfendazole bound strongly to cytochrome P450, giving rise to a type II spectrum, and inhibited noncompetitively the ethoxyresorufin O-deethylase and acetanilide hydroxylase activities, this confirmed that oxfendazole interacts only with the P450IA2 family. On the basis of a comparison of the enzymatic activities induced by various imidazole drugs, it was concluded that oxfendazole, like omeprazole and albendazole, behaved as a 3-methylcholanthrene-type inducer. These three benzimidazoles did not all belong to the same category of cytochrome P450 inducers as the antifungal drugs miconazole, clotrimazole and ketoconazole.
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Affiliation(s)
- C Gleizes
- Laboratoire de Pharmacologie-toxicologie INRA, Toulouse, France
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25
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Matsuura Y, Kotani E, Iio T, Fukuda T, Tobinaga S, Yoshida T, Kuroiwa Y. Structure-activity relationships in the induction of hepatic microsomal cytochrome P450 by clotrimazole and its structurally related compounds in rats. Biochem Pharmacol 1991; 41:1949-56. [PMID: 2039545 DOI: 10.1016/0006-2952(91)90135-r] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We investigated the structure-activity relationship in the induction of hepatic microsomal cytochrome P450 by clotrimazole and its structurally related compounds. For this purpose, we synthesized various compounds structurally analogous to clotrimazole and injected them into rats at a fixed dose of 0.2 mmol/kg. We found that the chlorine atom in clotrimazole was not necessary for the induction of cytochrome P450. The imidazole moiety of clotrimazole, however, was a very important structural component for the induction of cytochrome P450; triazole, but not pyrrole, could be substituted for this moiety. 1-Tritylimidazole, 1-diphenylmethylimidazole and 1-benzylimidazole were also found to be inducers of cytochrome P450, but, to a somewhat lesser extent, with a decreasing number of substituted phenyl groups. Thus, 1-benzylimidazole was a minimum structurally active unit for inducing cytochrome P450. In addition, 4-diphenylmethylpyridine and 4-benzylpyridine also induced cytochrome P450 to extents similar to those induced by the corresponding imidazole derivatives, but 4-benzylpiperidine lacked this effect. When the methylene unit of clotrimazole-related compounds was introduced by a hydroxy or amino group instead of imidazole, there was a less extensive increase in cytochrome P450 content. This inducing effect was lost completely by the lack of an imidazole moiety and imidazole itself. 1-Phenylethylimidazole and 1-benzylimidazole induced cytochrome P450 to a similar extent. All of these findings suggest that 1-substituted heteroaromatic compounds having two or more nitrogen atoms are likely to be required for inducing cytochrome P450. Immunoblot analysis revealed that clotrimazole and other various inducers found in this study increased cytochrome P450b/e content. These results could provide information on the effects of drugs and chemicals on cytochrome P450 induction.
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Affiliation(s)
- Y Matsuura
- Showa College of Pharmaceutical Sciences, Tokyo, Japan
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26
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Harmsworth WL, Franklin MR. Induction of hepatic and extrahepatic cytochrome P-450 and monooxygenase activities by N-substituted imidazoles. Xenobiotica 1990; 20:1053-63. [PMID: 2082595 DOI: 10.3109/00498259009046826] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
1. Seven N-substituted imidazoles, with abilities to induce rat hepatic cytochrome P-450 from 1.5- to 4-fold after 3 days of treatment (75 mg/kg daily), were investigated for their concurrent inductive effect in kidney, intestine and lung. 2. The ability of a compound to induce cytochrome P-450 in the liver did not correlate with the ability to induce in extrahepatic tissues, the highest magnitude hepatic inducer (clotrimazole) having little inductive effect in other organs. 3. Induction of cytochrome P-450 concentration was greater in kidney and intestine than in lung but, with the exception of the two imidazoles bearing either a benzyl or a 2-naphthylmethyl substituent, the degree of induction in the extrahepatic organs did not approach that seen in liver. 4. Different monooxygenase activities were preferentially induced by the individual N-substituted imidazoles in a single tissue, and activities induced by a compound in one tissue were not uniformly induced by that compound in other tissues. Induction of activities did not always correlate with an increase in cytochrome P-450 concentration.
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Affiliation(s)
- W L Harmsworth
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City 84112
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27
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Barnett CR, Gibson GG, Wolf CR, Flatt PR, Ioannides C. Induction of cytochrome P450III and P450IV family proteins in streptozotocin-induced diabetes. Biochem J 1990; 268:765-9. [PMID: 2141978 PMCID: PMC1131506 DOI: 10.1042/bj2680765] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of insulin-dependent diabetes on the hepatic microsomal activity of cytochrome P450III and P450IV family proteins was investigated in rats pretreated with streptozotocin. In order to discern between the effects of the diabetogen per se and those of the ensuing diabetes, streptozotocin-treated rats received in addition either nicotinamide to prevent the onset of diabetes or daily treatment with insulin to antagonize the effects of diabetes. Streptozotocin-treated rats displayed higher ethylmorphine and erythromycin N-demethylase activities and lauric acid hydroxylase activity. Increases were also detected immunologically by using monospecific polyclonal antibodies against the P450III and P450IV families. All effects were prevented by nicotinamide and effectively antagonized by insulin. In order to evaluate the role of the ketone bodies in the diabetes-induced increases in the above activities, rats were rendered hyperketonaemic by dietary administration of medium-chain triacylglycerols. These hyperketonaemic animals displayed high laurate hydroxylase activity and P450IV apoprotein levels, similar to those seen in the diabetic animals. Hyperketonaemia induced by dietary means caused a modest increase in the demethylation of erythromycin and had no significant effect on the N-demethylation of ethylmorphine. Furthermore, no marked increases were evident in the P450III apoprotein levels in the hyperketonaemic animals. It is concluded that insulin-dependent diabetes induces proteins of the P450III and P450IV families, and that the hyperketonaemia that accompanies diabetes is largely responsible for the changes in the latter family.
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Affiliation(s)
- C R Barnett
- Department of Biochemistry, University of Surrey, Guildford, U.K
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28
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Lavrijsen KL, Van Houdt JM, Van Dyck DM, Meuldermans WE, Heykants JJ. Induction potential of fluconazole toward drug-metabolizing enzymes in rats. Antimicrob Agents Chemother 1990; 34:402-8. [PMID: 2334152 PMCID: PMC171605 DOI: 10.1128/aac.34.3.402] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The induction of drug-metabolizing enzymes in rat liver was studied after subchronic administration of the new triazole antifungal agent fluconazole. The administered doses were 10, 40, and 160 mg/kg per day for 7 days. Fluconazole behaved as a high-magnitude inducer and significantly increased cytochrome P-450 concentrations already at 10 mg/kg (+42%). Cytochrome P-450 induction by fluconazole was dose dependent and reached a value of 302% of the control value at the dose of 160 mg/kg. The induction effects on cytochrome P-450 were also reflected in the drug-metabolizing enzyme activities in hepatic microsomes of pretreated rats. Fluconazole (160 mg/kg per day) preferentially induced the demethylase activities of N,N-dimethylaniline and p-nitroanisole to 258 and 281% of the control values, respectively. The detoxification enzyme UDP-glucuronosyltransferase was significantly lowered by fluconazole at the highest dose. A possible link between the induction potential and the pharmacokinetic properties of triazole antifungal agents is discussed.
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Affiliation(s)
- K L Lavrijsen
- Department of Drug Metabolism and Pharmacokinetics, Janssen Research Foundation, Beerse, Belgium
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29
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Ioannides C, Parke DV. The cytochrome P450 I gene family of microsomal hemoproteins and their role in the metabolic activation of chemicals. Drug Metab Rev 1990; 22:1-85. [PMID: 2199176 DOI: 10.3109/03602539008991444] [Citation(s) in RCA: 198] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- C Ioannides
- Department of Biochemistry, University of Surrey, Guildford, U.K
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30
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Smith JN, Ayrton AD, Chown J, Lewis DF, Ioannides C. Feprazone: an inducer of the P450 II B family of proteins in the rat. JOURNAL OF BIOCHEMICAL TOXICOLOGY 1990; 5:9-12. [PMID: 2402005 DOI: 10.1002/jbt.2570050103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The ability of feprazone to induce the hepatic microsomal mixed-function oxidases was investigated in the rat, with emphasis being placed on the nature of the cytochrome P-450 family induced. Treatment with feprazone enhanced the p-hydroxylation of aniline and the dealkylations of benzphetamine and pentoxyresorufin but had no effect on the O-deethylation of ethoxyresorufin. The same treatment had no major effect on total cytochrome P-450 levels but increased the spectral interaction of metyrapone with reduced cytochrome P-450. Immunoblots employing monospecific polyclonal antibodies revealed that feprazone induces the apoprotein levels of the P450 II B, but not of the P450 I, family. It is concluded that feprazone is an inducer of the rat hepatic mixed-function oxidase system showing selectivity toward the P450 II B family.
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Affiliation(s)
- J N Smith
- Department of Biochemistry, University of Surrey, Guildford, United Kingdom
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31
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González P, Tuñón MJ, Manrique V, Garcia-Pardo LA, González J. Changes in hepatic cytosolic glutathione S-transferase enzymes induced by clotrimazole treatment in rats. Clin Exp Pharmacol Physiol 1989; 16:867-71. [PMID: 2612064 DOI: 10.1111/j.1440-1681.1989.tb01526.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1. The influence of the antifungal agent clotrimazole on cytosolic glutathione S-transferase activities was studied in male Wistar rats. 2. Animals received clotrimazole by gastric lavage for 3 days (75 mg/kg per day). Hepatic glutathione S-transferase activity was determined with five different substrates: 1-chloro-2,4-dinitrobenzene (CDNB), 1,2-dichloro-4-nitrobenzene (DCNB), p-nitro-benzyl chloride (PNBC), ethacrynic acid (EA) and trans-4-phenyl-3-buten-2-one (TPBO). 3. The largest increases in glutathione S-transferase activity were found with CDNB, DCNB and PNBC (+61%, +50% and +50%, respectively, when expressed per mg of cytosolic protein). Enzyme activity toward EA was induced to a lower extent (+33%). Changes in the formation of the conjugate of TPBO were relatively small (+22%). 4. These data indicate a differential induction of glutathione S-transferase isoenzymes and suggest that clotrimazole is a phenobarbital-type inducer of enzyme activity.
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Affiliation(s)
- P González
- Department of Physiology, Pharmacology and Toxicology, University of León, Spain
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Lewis DF, Rodrigues AD, Ioannides C, Parke DV. Adverse reactions of imidazole antifungal agents: computer graphic studies of cytochrome P-450 interactions. JOURNAL OF BIOCHEMICAL TOXICOLOGY 1989; 4:231-4. [PMID: 2634093 DOI: 10.1002/jbt.2570040405] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The imidazole antifungal agents give rise to adverse reactions and clinically relevant drug interactions. This is due to lack of specificity of the antifungal agents that interact avidly not only with the fungal but also with mammalian cytochrome P-450 proteins. A computer graphic technique capable of predicting the interaction of these structurally-related imidazoles with fungal and mammalian cytochrome P-450 proteins is described. This prediction is achieved by comparing the molecular conformation of these drugs with lanosterol, the substrate of the fungal cytochrome P-450, and with phenobarbitone, an inducing agent of a family of mammalian cytochrome P-450, toward which the antifungal agents show highest inhibitory activity.
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Affiliation(s)
- D F Lewis
- Department of Biochemistry, University of Surrey, Guildford, United Kingdom
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Ayrton AD, Ioannides C, Walker R. Induction of rat hepatic cytochrome P-450 I proteins by the antimutagen anthraflavic acid. Food Chem Toxicol 1988; 26:909-15. [PMID: 3209131 DOI: 10.1016/0278-6915(88)90088-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Administration of the antimutagen anthraflavic acid to rats gave rise to significant increases in the hepatic microsomal O-deethylations of ethoxyresorufin and ethoxycoumarin, but not in the O-dealkylation of pentoxyresorufin nor in cytosolic glutathione S-transferase activity. Immunoblot studies of solubilized microsomes from anthraflavic acid-treated rats revealed that anthraflavic acid induced the apoproteins P-450 I A1 and A2 but not P-450 B1 and B2. Pretreatment with anthraflavic acid resulted in a marked increase in the in vitro bioactivation of 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole and 2-amino-3,2-amino-3-methylimidazomethylimidazo[4,5-f]-quinoline (IQ) to mutagenic intermediate(s); IQ is a carcinogen against which anthraflavic acid has displayed strong antimutagenic effect in the Ames test when incorporated into the metabolic activation system. The increase in mutagenicity of IQ was the result of enhancement of both the microsomal and cytosolic activation steps. It is concluded that anthraflavic acid is a specific inducer of P-450 I proteins in the rat and this compound is not only unlikely to exhibit any anticarcinogenic effect in vivo but may act as a co-carcinogen.
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Affiliation(s)
- A D Ayrton
- Department of Biochemistry, University of Surrey, Guildford, England
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