1
|
Alhusainy W, Paini A, Punt A, Louisse J, Spenkelink A, Vervoort J, Delatour T, Scholz G, Schilter B, Adams T, van Bladeren P, Rietjens I. Identification of nevadensin as an important herb-based constituent inhibiting estragole bioactivation and physiology-based biokinetic modeling of its possible in vivo effect. Toxicol Appl Pharmacol 2010; 245:179-90. [DOI: 10.1016/j.taap.2010.02.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 02/17/2010] [Accepted: 02/26/2010] [Indexed: 10/19/2022]
|
2
|
Mizuno K, Katoh M, Okumura H, Nakagawa N, Negishi T, Hashizume T, Nakajima M, Yokoi T. Metabolic Activation of Benzodiazepines by CYP3A4. Drug Metab Dispos 2008; 37:345-51. [DOI: 10.1124/dmd.108.024521] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
3
|
Ohbuchi M, Miyata M, Nagai D, Shimada M, Yoshinari K, Yamazoe Y. Role of Enzymatic N-Hydroxylation and Reduction in Flutamide Metabolite-Induced Liver Toxicity. Drug Metab Dispos 2008; 37:97-105. [DOI: 10.1124/dmd.108.021964] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
4
|
Chen K, Cole RB, Santa Cruz V, Blakeney EW, Kanz MF, Dugas TR. Characterization of biliary conjugates of 4,4'-methylenedianiline in male versus female rats. Toxicol Appl Pharmacol 2008; 232:190-202. [PMID: 18692083 DOI: 10.1016/j.taap.2008.06.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Accepted: 06/20/2008] [Indexed: 11/18/2022]
Abstract
4,4'-Methylenedianiline (4,4'-diaminodiphenylmethane; DAPM) is an aromatic diamine used in the production of numerous polyurethane foams and epoxy resins. Previous studies in rats revealed that DAPM initially injures biliary epithelial cells of the liver, that the toxicity is greater in female than in male rats, and that the toxic metabolites of DAPM are excreted into bile. Since male and female rats exhibit differences in the expression of both phase I and phase II enzymes, our hypothesis was that female rats either metabolize DAPM to more toxic metabolites or have a decreased capacity to conjugate metabolites to less toxic intermediates. Our objective was thus to isolate, characterize, and quantify DAPM metabolites excreted into bile in both male and female bile duct-cannulated Sprague Dawley rats. The rats were gavaged with [(14)C]-DAPM, and the collected bile was subjected to reversed-phase HPLC with radioisotope detection. Peaks eluting from HPLC were collected and analyzed using electrospray MS and NMR spectroscopy. HPLC analysis indicated numerous metabolites in both sexes, but male rats excreted greater amounts of glutathione and glucuronide conjugates than females. Electrospray MS and NMR spectra of HPLC fractions revealed that the most prominent metabolite found in bile of both sexes was a glutathione conjugate of an imine metabolite of a 4'-nitroso-DAPM. Seven other metabolites were identified, including acetylated, cysteinyl-glycine, glutamyl-cysteine, glycine, and glucuronide conjugates. While our prior studies demonstrated increased covalent binding of DAPM in the liver and bile of female compared to male rats, in these studies, SDS-PAGE with autoradiography revealed 4-5 radiolabeled protein bands in the bile of rats treated with [(14)C]-DAPM. In addition, these bands were much more prominent in female than in male rats. These studies thus suggest that a plausible mechanism for the increased sensitivity of female rats to DAPM toxicity may be decreased conjugation of reactive DAPM metabolites, leading to greater levels of protein adduct formation.
Collapse
Affiliation(s)
- Kan Chen
- Department of Chemistry, University of New Orleans, New Orleans, LA, USA
| | | | | | | | | | | |
Collapse
|
5
|
Liquid chromatography-electrospray tandem mass spectrometry investigations of fragmentation pathways of biliary 4,4'-methylenedianiline conjugates produced in rats. Anal Bioanal Chem 2008; 391:271-8. [PMID: 18373088 DOI: 10.1007/s00216-008-1954-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 01/30/2008] [Accepted: 02/07/2008] [Indexed: 10/22/2022]
Abstract
4,4'-methylenedianiline (DAPM) is the main building block for production of 4,4'-methylenediphenyldiisocyanate that has been widely used in the manufacturing of polyurethane materials including medical devices. Although it was revealed that damage to biliary epithelial cells of the liver and common bile duct occurred upon acute exposure to DAPM, the exact mechanism of DAPM toxicity is not fully understood. Both phase I and II biotransformations of DAPM, some of which generate reactive intermediates, are characterized in detail by liquid chromatography electrospray tandem mass spectrometry. The two most prominent metabolites found in rat bile (M2 and M7) implicated glutathione, glucuronic acid, and glycine conjugations (phase II) following hydroxylation, and N-oxidation (phase I). Their decomposition pathways, as evidenced by MS(n) experiments, have been elucidated in detail. [figure: see text]
Collapse
|
6
|
Gresner P, Gromadzinska J, Wasowicz W. Polymorphism of selected enzymes involved in detoxification and biotransformation in relation to lung cancer. Lung Cancer 2007; 57:1-25. [PMID: 17337085 DOI: 10.1016/j.lungcan.2007.02.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 01/30/2007] [Accepted: 02/04/2007] [Indexed: 01/22/2023]
Abstract
Available data indicate that there are significant differences in individual susceptibility to lung cancer within the human population. It is believed to be underlie by inherited genetic predispositions related to the genetic polymorphism of several enzymes involved in the detoxification and xenobiotic metabolism. In this review, we collect and discuss the evidence reported up to date on the association between lung cancer and genetic polymorphism of cytochromes P450, N-acetyltransferase, glutathione S-transferases, microsomal epoxide hydrolase, NAD(P)H:quinone oxidoreductase, myeloperoxidase and glutathione peroxidase. All these genes might appear to be candidates for lung cancer susceptibility genes, nevertheless, the present state of the art still offers only a limited explanation of the link between such polymorphisms and increased risk of lung cancer.
Collapse
Affiliation(s)
- Peter Gresner
- Department of Toxicology and Carcinogenesis, Nofer Institute of Occupational Medicine, Lodz, Poland.
| | | | | |
Collapse
|
7
|
Goda R, Nagai D, Akiyama Y, Nishikawa K, Ikemoto I, Aizawa Y, Nagata K, Yamazoe Y. Detection of a new N-oxidized metabolite of flutamide, N-[4-nitro-3-(trifluoromethyl)phenyl]hydroxylamine, in human liver microsomes and urine of prostate cancer patients. Drug Metab Dispos 2006; 34:828-35. [PMID: 16507648 DOI: 10.1124/dmd.105.008623] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Flutamide (2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide), a nonsteroidal antiandrogen, is used in the treatment of prostate cancer but is occasionally associated with hepatic dysfunction. In the present study, the metabolism of flutamide including the formation of the possible reactive toxic metabolites was investigated using human liver microsomes and 10 isoforms of recombinant human cytochrome P450 (P450). 2-Hydroxyflutamide (OH-flutamide) and 4-nitro-3-(trifluoromethyl)phenylamine (FLU-1) were the main products of flutamide metabolism in human liver microsomes. The formation of OH-flutamide was markedly inhibited by ellipticine, an inhibitor of CYP1A1/1A2, and was mainly catalyzed by the recombinant CYP1A2. FLU-1 was also produced from OH-flutamide, but its metabolic rate was much less than that from flutamide. An inhibitor of carboxylesterase, bis-(p-nitrophenyl)phosphoric acid, completely inhibited the formation of FLU-1 from flutamide in human liver microsomes. A new metabolite, N-[4-nitro-3-(trifluoromethyl)phenyl]hydroxylamine (FLU-1-N-OH), was detected as a product of the reaction of FLU-1 with human liver microsomes and identified by comparison with the synthetic standard. The formation of FLU-1-N-OH was markedly inhibited by the addition of miconazole, an inhibitor of CYP3A4, and was mediated by recombinant CYP3A4. Furthermore, FLU-1-N-OH was detected mostly as the conjugates (glucuronide/sulfate) in the urine of prostate cancer patients collected for 3 h after treatment with flutamide. The formation of FLU-1-N-OH, however, did not differ between patients with and without abnormalities of hepatic functions among a total of 29 patients. The lack of an apparent association of the urinary excretion of FLU-1-N-OH and hepatic disorder may suggest the involvement of an additional unknown factor in the mechanisms of flutamide hepatotoxicity.
Collapse
Affiliation(s)
- Rika Goda
- R&D Division, Pharmaceuticals Group, Nippon Kayaku Co., Ltd., 3-31-12 Shimo, Tokyo 115-8588, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Wang LQ, Lehmler HJ, Robertson LW, James MO. Polychlorobiphenylols are selective inhibitors of human phenol sulfotransferase 1A1 with 4-nitrophenol as a substrate. Chem Biol Interact 2006; 159:235-46. [PMID: 16413005 DOI: 10.1016/j.cbi.2005.12.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 12/05/2005] [Accepted: 12/06/2005] [Indexed: 11/29/2022]
Abstract
Polychlorobiphenylols (OH-PCBs) were reported as potent inhibitors of estrogen sulfotransferase, thyroid hormone and 3-hydroxybenzo(a)pyrene sulfotransferases. The aim of this study was to examine the effects of selected OH-PCBs on SULT1A1 activity in human liver cytosol, measured with 4microM 4-nitrophenol, a concentration considered to be diagnostic for selectively detecting SULT1A1. All the OH-PCBs studied inhibited the sulfonation of 4-nitrophenol in human liver cytosol. Among the eighteen OH-PCBs studied, 3'-OH-CB3 (4-chlorobiphenyl-3'-ol) was the most potent inhibitor (IC(50): 0.73+/-0.15microM, mean+/-S.D., n=3). The least potent inhibitor studied was 6'-OH-CB35 (3,3',4-trichlorobiphenyl-6'-ol) with IC(50): 49.1+/-10.8microM. The IC(50) values of the other OH-PCBs studied ranged from 0.78 to 3.76microM. Some OH-PCBs with various inhibitory potencies with human liver cytosol were selected for study with recombinant human SULT1A1 and SULT1B1. These OH-PCBs showed more potent inhibition of 4-nitrophenol sulfonation with SULT1A1 than with human liver cytosol. The IC(50) values with human liver cytosol showed a perfect linear correlation with those found with SULT1A1 (r(2)=1), but not with SULT1B1 (r(2)=0.21). The results suggested that in these human samples SULT1A1 was predominantly responsible for the sulfonation of 4-nitrophenol, with very little or no contribution from SULT1B1. The kinetics of inhibition were studied with 4'-OH-CB165, which is similar in structure to OH-PCBs found in human blood. The 4'-OH-CB165 was a mixed noncompetitive-uncompetitive inhibitor (K(i)=1.80+/-0.2microM, K(ies)=0.16+/-0.02microM). Finally, it was demonstrated that the tested OH-PCBs were themselves only slowly sulfonated by human sulfotransferases in the presence of (35)S-PAPS, as measured by the production of (35)S-labeled metabolites. Although this series of 18 OH-PCBs was too small to draw conclusions about structure-potency relationships, this work demonstrated that several OH-PCBs were potent inhibitors of 4-nitrophenol sulfonation but poor substrates in human liver cytosol, and suggested that OH-PCBs may inhibit the sulfation rate of those xenobiotics sulfated by SULT1A1.
Collapse
Affiliation(s)
- Li-Quan Wang
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville 32610-0485, USA
| | | | | | | |
Collapse
|
9
|
Sharma V, Duffel MW. Comparative molecular field analysis of substrates for an aryl sulfotransferase based on catalytic mechanism and protein homology modeling. J Med Chem 2002; 45:5514-22. [PMID: 12459019 DOI: 10.1021/jm010481c] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Comparative Molecular Field Analysis (CoMFA) methods were used to produce a 3D-QSAR model that correlated the catalytic efficiency of rat hepatic aryl sulfotransferase (AST) IV, expressed as log(k(cat)/K(m)), with the molecular structures of its substrates. A total of 35 substrate molecules were used to construct a CoMFA model that was evaluated on the basis of its leave-one-out cross-validated partial least-squares value (q(2)) and its ability to predict the activity of six additional substrates not used in the training set. The model was constructed using substrate conformations that favored (1) proton abstraction by the catalytic histidine residue, (2) an in-line sulfuryl-group transfer mechanism, and (3) constraints imposed by the residues lining the substrate binding pocket of a homology model of AST IV. This CoMFA model had a q(2) value of 0.691, and it successfully predicted the activities of the six molecules not used in the training set. A final CoMFA model was constructed using the same methodology but with molecules from both the training set and the test set. Its q(2) value was 0.701, and it had a non-cross-validated r(2) value of 0.922. The contour coefficient map generated by this CoMFA was overlaid on the amino acids in the substrate-binding pocket of the homology model of AST IV and found to show a good fit. Additionally external validation was obtained by using the CoMFA model to design substrates that show high activities. These results establish a methodology for prediction of the substrate specificity of this sulfotransferase based on CoMFA methods that are guided by both the homology model and the catalytic mechanism of the enzyme.
Collapse
Affiliation(s)
- Vyas Sharma
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, The University of Iowa, Iowa City, Iowa 52242, USA
| | | |
Collapse
|
10
|
Weisburger JH. Comments on the history and importance of aromatic and heterocyclic amines in public health. Mutat Res 2002; 506-507:9-20. [PMID: 12351140 DOI: 10.1016/s0027-5107(02)00147-1] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The carcinogenic risk of aromatic amines in humans was first discovered when a physician related the occurrence of urinary bladder cancer to the occupation of his patients. They were employed in the dyestuff industry, chronically exposed to large amounts of intermediate arylamines. Laboratory investigations disclosed that rats and mice administered specific azo dyes arylamines or derivatives developed cancer, primarily in the liver. Also, at that time, a possible pesticide, 2-aminofluorene, was tested for chronic toxicity, revealing that it rapidly induced cancers in several organs of rodents. This led to investigations on the mode of action of this class of chemicals, including their metabolic conversion. Biochemical activation to more reactive N-hydroxy compounds was found to occur, mostly in the liver, through what is now known as the cytochrome p450 enzyme systems, and also through prostaglandin synthetases. There were species differences. Guinea pigs were resistant to carcinogenesis because of the low titer of the necessary activating enzymes. In target tissues, a second essential reaction was necessary, namely acylation or sulfate ester formation. The reactive compounds produced display attributes of genotoxicity in appropriate test systems. Interest in this class of compounds increased when of Sugimura and colleagues discovered the formation of mutagens at the surface of cooked meat or fish, that were identified as heterocyclic amines (HCAs). These compounds undergo the same type of activation reactions, as do other arylamines. Epidemiological data suggest that meat eaters may have a higher risk of breast and colon cancer. HCAs induced cancer in rats in these organs and also in the prostate and the pancreas. In addition, there is some evidence that they affect the vascular system. The formation of HCAs during cooking can be decreased by natural and synthetic antioxidants, by tryptophan or proline, or by removing the essential creatine through brief microwave cooking prior to frying or broiling. The amounts of HCAs in cooked foods are small, but other components in diet such as omega-6-polyunsaturated oils have powerful promoting effects in target organs of HCAs. On the other hand, the action of HCAs may be decreased by foods containing antioxidants, such as vegetables, soy, and tea. Some constituents in foods also induce phase II enzymes that detoxify reactive HCA metabolites. Additional mechanisms involved decreased growth of neoplasms by intake of protective foods. Possibly, the carcinogenic effect of HCAs is accompanied by the presence of reactive oxygen species (ROS), which are also inhibited by antioxidants. World-wide, there have been many contributors to knowledge in this field. Adequate information may permit now to adjust lifestyle and lower the risk of human disease stemming from this entire class of aryl and HCA.
Collapse
|
11
|
Yoshinari K, Petrotchenko EV, Pedersen LC, Negishi M. Crystal structure-based studies of cytosolic sulfotransferase. J Biochem Mol Toxicol 2001; 15:67-75. [PMID: 11284047 DOI: 10.1002/jbt.1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Sulfation is a widely observed biological reaction conserved from bacterium to human that plays a key role in various biological processes such as growth, development, and defense against adversities. Deficiencies due to the lack of the ubiquitous sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) are lethal in humans. A large group of enzymes called sulfotransferases catalyze the transfer reaction of sulfuryl group of PAPS to the acceptor group of numerous biochemical and xenochemical substrates. Four X-ray crystal structures of sulfotransferases have now been determined: cytosolic estrogen, hydroxysteroid, aryl sulfotransferases, and a sulfotransferase domain of the Golgi-membrane heparan sulfate N-deacetylase/N-sulfotransferase 1. These have revealed the conserved core structure of the PAPS binding site, a common reaction mechanism, and some information concerning the substrate specificity. These crystal structures introduce a new era of the study of the sulfotransferases.
Collapse
Affiliation(s)
- K Yoshinari
- Pharmacogenetics Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | | | | | | |
Collapse
|
12
|
Boudreau MD, Baker DG, Taylor HW, Barker SA, Means JC. Suppression of arylamine toxicity in the Fischer-344 rat following ingestion of a complex mixture. Toxicol Pathol 2001; 29:333-43. [PMID: 11442020 DOI: 10.1080/019262301316905291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The toxic effects of a mixture of 2-aminoanthracene (2-AA), benzanthracene (BA), and dinitropyrene isomers (DNP), and the toxic effects of these compounds individually, were investigated in the Fischer-344 rat following dietary exposure via a powdered basal diet. Animals were sacrificed at 14-, 30-, and 80-days of dietary exposure. Exposure to dietary 2-AA alone induced anorexia, cachexia, variable mortality, and altered serum chemistry profiles in the F-344 rat. Reduced lymphocyte counts were also shown in rats exposed to 2-AA. A temporal pattern of effect of 2-AA dietary exposure was observed in the progression of hepatic lesions in exposed animals. Dietary exposure to either DNP isomers or BA at a 10-fold higher concentration in the diet, relative to 2-AA, did not induce detectable toxic responses. However, exposure of rats to a mixture of 2-AA, BA, and DNP isomers (100 mg/kg, 1.0 g/kg, and 1.0 g/kg of diet, respectively) resulted in the attenuation of toxic effects when compared to exposure of F-344 rats to 2-AA alone. These results indicate that the toxic effects of 2-AA are suppressed by co-administration of DNP and BA and suggest that compound interactions need to be considered when predicting the toxic potential of specific environmental pollutants.
Collapse
Affiliation(s)
- M D Boudreau
- Department of Physiology, Pharmacology, and Toxicology, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803, USA
| | | | | | | | | |
Collapse
|
13
|
Kranendonk M, Laires A, Rueff J, Estabrook WR, Vermeulen NP. Heterologous expression of xenobiotic mammalian-metabolizing enzymes in mutagenicity tester bacteria: an update and practical considerations. Crit Rev Toxicol 2000; 30:287-306. [PMID: 10852498 DOI: 10.1080/10408440091159211] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
There is an increasing need for metabolic competent cell systems for the mechanistic studies of biotransformation of xenobiotics in toxicology in general and in genotoxicology in particular. These cell systems combine the heterologous expression of a particular mammalian biotransformation enzyme with a specific target/ end point by which a functional analysis of the expressed gene product in the (geno)toxicity of chemicals can be performed. cDNAs of an increasing number of mammalian biotransformation enzymes is being cloned. The construction of specific expression vectors permits their heterologous expression in laboratory bacteria, such as Escherichia coli strains. This development does not only allow biochemical and enzymatic studies of (pure) enzyme preparations but also facilitates the engineering of metabolically competent mutagenicity tester bacteria, thereby providing new tools for genotoxicity testing and for studying of the roles of biotransformation in chemical carcinogenesis. In this review, we describe an update as well as an evaluation of enzymes expressed in mutagenicity tester bacteria. Four types of biotransformation enzymes are now expressed in these bacteria, namely, GSTs, CYPs, NATs, and STs. The expression of these enzymes in the tester bacteria and their subsequent application in mutagenicity assays demonstrates that heterologous expression in this type of bacteria has a number implications for the functionality of the biotransformation enzymes as well as for the functioning of the tester bacteria in mutagenicity detection. We also describe here a number of practical considerations in this regard.
Collapse
Affiliation(s)
- M Kranendonk
- Department of Genetics, Faculty of Medical Sciences, Universidade Nova de Lisboa, Lisbon, Portugal.
| | | | | | | | | |
Collapse
|
14
|
Lee HC, Kumar P, McEwan AJ, Wiebe LI, Mercer JR. Synthesis, radiolabeling, and biodistribution of putative metabolites of iodoazomycin arabinoside. Nucl Med Biol 2000; 27:61-8. [PMID: 10755647 DOI: 10.1016/s0969-8051(99)00089-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Scintigraphic evaluation of patients with advanced oncological disease showed uptake of radioactivity in the brain following administration of the hypoxic imaging agent 123I-iodoazomycin arabinoside (123I-IAZA). Three proposed metabolites of IAZA--methyl 5-deoxy-5-iodo-D-arabinofuranoside, methyl 2,3-di-O-acetyl-5-deoxy-5-iodo-alpha-D-arabinofuranoside, and 1-(5-deoxy-5-iodo-alpha-D-arabinofuranosyl)-2-aminoimidazole (IAIA)--were synthesized, radiolabeled with 125I, and investigated in normal and tumor-bearing murine models for their contribution to this unusual phenomenon. The three compounds were readily radiolabeled by melt or solvent exchange procedures. Biodistribution data indicated rapid blood clearance, rapid excretion, and little tissue accumulation in the brain. IAIA showed significant tumor to blood ratios at 4 h (4.3:1) and liver to blood ratios at 24 h (30:1).
Collapse
Affiliation(s)
- H C Lee
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada
| | | | | | | | | |
Collapse
|
15
|
Hsieh FI, Pu YS, Chern HD, Hsu LI, Chiou HY, Chen CJ. Genetic polymorphisms of N-acetyltransferase 1 and 2 and risk of cigarette smoking-related bladder cancer. Br J Cancer 1999; 81:537-41. [PMID: 10507782 PMCID: PMC2362925 DOI: 10.1038/sj.bjc.6690727] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/1998] [Revised: 02/21/1999] [Accepted: 03/02/1999] [Indexed: 01/13/2023] Open
Abstract
Aromatic amines from cigarette smoking or occupational exposure, recognized risk factors for bladder cancer, are metabolized by N-acetyltransferases (NAT). This study examined the association of (NAT) 1 and 2 genotypes with the risk of smoking-related bladder cancer. A total of 74 pathologically confirmed bladder cancer patients and 184 controls were serially recruited from the National Taiwan University Hospital. History of cigarette smoking and other risk factors for bladder cancer was obtained through standardized questionnaire interview. Peripheral blood lymphocytes were collected from each subject and genotyped for NAT1 and NAT2 by DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism methods. Allele frequency distributions of NAT1 and NAT2 were similar between cases and controls. There was a significant dose-response relationship between the risk of bladder cancer and the quantity and duration of cigarette smoking. The biological gradients were significant among subjects carrying NAT1*10 allele or NAT2 slow acetylators, but not among NAT2 rapid acetylators without NAT1*10 allele. The results are consistent with the hypothesis that NAT1 and NAT2 might modulate the susceptibility to bladder cancer associated with cigarette smoking.
Collapse
Affiliation(s)
- F I Hsieh
- Graduate Institute of Epidemiology, College of Public Health, Taipei, Taiwan
| | | | | | | | | | | |
Collapse
|
16
|
FILIADIS IOANNISF, GEORGIOU IOANNIS, ALAMANOS YANNIS, KRANAS VASILIS, GIANNAKOPOULOS XENOPHON, LOLIS DIMITRIOS. GENOTYPES OF N-ACETYLTRANSFERASE-2 AND RISK OF BLADDER CANCER: A CASE-CONTROL STUDY. J Urol 1999. [DOI: 10.1016/s0022-5347(05)69002-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
17
|
Abstract
Tea is the most popular beverage, consumed by over two thirds of the world's population. Tea is processed differently in different parts of the world to give green (20%), black (78%) or oolong tea (2%). Green tea is consumed mostly in Japan and China. The antimutagenic and anticarcinogenic activities of green tea are extensively examined. The chemical components of green and black tea are polyphenols, which include EC, ECG, EGC, EGCG and TFs. This article reviews the epidemiological and experimental studies on the antimutagenicity and anticarcinogenicity of tea extracts and tea polyphenols. In Japan, an epidemiological study showed an inverse relationship between habitual green tea drinking and the standardized mortality rates for cancer. Some cohort studies on Chanoyu (Japanese tea ceremony) women teachers also showed that their mortality ratio including deaths caused by malignant neoplasms were surprisingly low. The antimutagenic activity against various mutagens of tea extracts and polyphenols including ECG and EGCG has been demonstrated in microbial systems (Salmonella typhimurium and Escherichia coli), mammalian cell systems and in vivo animal tests. The anticarcinogenic activity of tea phenols has been shown in experimental animals such as rats and mice, in transplantable tumors, carcinogen-induced tumors in digestive organs, mammary glands, hepatocarcinomas, lung cancers, skin tumors, leukemia, tumor promotion and metastasis. The mechanisms of antimutagenesis and anticarcinogenesis of tea polyphenols suggest that the inhibition of tumors may be due to both extracellular and intracellular mechanisms including the modulation of metabolism, blocking or suppression, modulation of DNA replication and repair effects, promotion, inhibition of invasion and metastasis, and induction of novel mechanisms.
Collapse
Affiliation(s)
- Y Kuroda
- National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | | |
Collapse
|
18
|
Apostolides Z, Balentine DA, Harbowy ME, Hara Y, Weisburger JH. Inhibition of PhIP mutagenicity by catechins, and by theaflavins and gallate esters. Mutat Res 1997; 389:167-72. [PMID: 9093380 DOI: 10.1016/s1383-5718(96)00143-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Aqueous solutions of gallic acid, methyl gallate, catechins, theaflavins and tannic acid were tested for inhibition of the mutagenicity of PhIP in the Salmonella typhimurium TA98 assay with an S9 fraction from the liver of rats induced with alpha-naphthoflavone and phenobarbital. The IC50S were in the 80-250 microM range for the gallated catechins, theaflavins and tannic acid. No inhibition could be found with these compounds when a direct acting mutagen was used. This indicates that the anti-mutagenic properties of these phenolic compounds may be due to their inhibition of the cytochrome P-450 enzymes.
Collapse
Affiliation(s)
- Z Apostolides
- Department of Biochemistry, University of Pretoria, South Africa
| | | | | | | | | |
Collapse
|
19
|
O'Brien PJ, Hales BF, Josephy PD, Castonguay A, Yamazoe Y, Guengirich FP. Chemical carcinogenesis, mutagenesis, and teratogenesis. Can J Physiol Pharmacol 1996. [DOI: 10.1139/y96-054] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
20
|
Walle T, Eaton EA, Walle UK. Quercetin, a potent and specific inhibitor of the human P-form phenosulfotransferase. Biochem Pharmacol 1995; 50:731-4. [PMID: 7669078 DOI: 10.1016/0006-2952(95)00190-b] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The natural product quercetin was a potent inhibitor of the human P-form phenolsulfo-transferase with an IC50 value of 0.10 +/- 0.03 microM (mean +/- SEM; N = 5), which was three to four orders of magnitude more potent than its inhibition of other human sulfotransferases. The inhibition was noncompetitive with a Ki value of 0.10 microM. The potency and mechanism of this inhibition appear similar to those of the current standard P-form inhibitor, 2,6-dichloro-4-nitrophenol. Among other flavonoids examined, kaempferol was found to have an IC50 value of 0.39 +/- 0.07 microM, naringenin 10.6 +/- 1.6 microM and naringin 265 +/- 90 microM (N = 3). These observations suggest the potential for clinically important pharmacologic and toxicologic interactions by flavonoid-containing foods and beverages.
Collapse
Affiliation(s)
- T Walle
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston 29425, USA
| | | | | |
Collapse
|
21
|
Kiehlbauch CC, Lam YF, Ringer DP. Homodimeric and heterodimeric aryl sulfotransferases catalyze the sulfuric acid esterification of N-hydroxy-2-acetylaminofluorene. J Biol Chem 1995; 270:18941-7. [PMID: 7642552 DOI: 10.1074/jbc.270.32.18941] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Three aryl sulfotransferases (ASTs) isolated from rat liver catalyze the sulfuric acid esterification of the carcinogen N-hydroxy-2-acetylaminofluorene (N-OH-2AAF). These three ASTs were separated by high resolution anion exchange chromatography and were designated Q1, Q2, and Q3. Q1 and Q2 had high N-OH-2AAF sulfonation activity, whereas Q3 showed low activity. Reversed phase high performance liquid chromatography/mass spectrometry analysis showed Q1-Q3 to be comprised of 33,945- and 35,675-Da protein subunits. Q1 contained only the 35,675-Da protein subunit, Q2 contained equal quantities of 33,945- and 35,675-Da subunits, and Q3 contained only the 33,945-Da subunit. The subunit compositions of Q1-Q3 were confirmed by immunochemical analysis. Size exclusion high performance liquid chromatography confirmed that the active quaternary structure of the three isoenzymes was dimeric. Analysis of liver cytosols for the relative contributions of Q1-Q3 to total cytosolic N-OH-2AAF sulfotransferase activity indicated the Q1, Q2, and Q3 accounted for 44, 46, and 10% of the activity, respectively. These results demonstrate the existence of both homodimeric and heterodimeric aryl sulfotransferases and show that two ASTs, a homodimer of 35,675-Da subunits and a heterodimer of a 33,945- and a 35,675-Da subunit, are primarily responsible for hepatic N-OH-2AAF sulfotransferase activity.
Collapse
Affiliation(s)
- C C Kiehlbauch
- Oklahoma Medical Research Foundation, Noble Center for Biomedical Research, Oklahoma City 73104-5046, USA
| | | | | |
Collapse
|
22
|
Clement B, Linne S. P216 genotoxic activities of N-hydroxylated derivatives of amidines, guanidines and amidinohydrazones in salmonella typhimurium. Eur J Pharm Sci 1994. [DOI: 10.1016/0928-0987(94)90389-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|