Strategy for genotoxicity testing—Metabolic considerations

Ku, Warren W.; Bigger, Anita; Brambilla, Giovanni; Glatt, Hansruedi; Gocke, Elmar; Guzzie, Peggy J.; Hakura, Atsushi; Honma, Masamitsu; Martus, Hans-Joerg; Obach, R. Scott; Roberts, Stanley A.

doi:10.1016/j.mrgentox.2006.10.004

Cited by 98 publications

(55 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, based on the structural knowledge of the chemicals to be tested, suitable strain/cell, exogeneous activation systems and tests should be chosen for genotoxicity screening [15,21]. In this study, since 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane (I) derivates involve nitro groups, makes advantageous the use of the umu-test, using NM2009 and NM1011 strains especially designed for detecting the mutagenicity of nitroarenes.…”

Section: Resultsmentioning

confidence: 99%

“…The nitro groups are regarded as mutagenic and carcinogenic in several drugs, like in the case of metronidazole. On the other hand, nitazoxanide, has a wide range antiviral activity, was found to be weak positive in only Ames tester strain TA102, whereas non-mutagenic in other Ames tester strains [15,16]. Nowadays, antiviral therapies utilize combination therapies involving generally nucleoside analogs such as zidovudine (AZT) and lamivudine (3TC).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Genotoxicity of potent antiviral 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane derivatives designed as drug agents

Doğan¹,

Durusoy²,

Gökçe³

et al. 2014

Turk J Bioch

View full text Add to dashboard Cite

Objective: Genotoxic potentials of six selected nitrobutane (I) derivatives designed as drug agents were tested here for the first time using umu-microplate test system. An important principle in drug development is to perform safety tests of previously determined significant drug activity in in vitro assays. This may be even more crucial than its efficiency in terms of experimental conditions, since it is important in chemotherapy to treat without risk for the patient. Methods: Umu-microplate test system is especially designed for detecting the mutagenicity of nitro compounds. 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane (I) derivatives involve nitro groups. Therefore umu-microplate test system has been chosen for our analysis. Evaluation of the SOS inducing activity of the tested compounds was examined with the umu-microplate test system using Salmonella typhimurium NM1011 (overexpressed NR (nitroreductase)) and S.typhimurium NM2009 (overexpressed O-At (O-acethyltransferase))strains which are sensitive to nitro compounds. Chlorophenol red-β-D-galactopyranoside (CPRG) and O-nitrophenyl-β-D-galactopyranoside (ONPG) were used as substrate in the enzyme assays and also the well-known genotoxic nitro compound, 4-nitroquinoline 1-oxide (4NQO), was the positive control in the test. Results: Although the β-galactosidase activities with using CPRG were three fold higher than ONPG, parallel results were obtained for both substrates and strains with all compounds tested. For all compounds, the induction of umuC gene expression was found to be almost the same for the strains that overexpress NR and O-At. The derivatives tested didn't caused an evident induction in both strains overexpressed NR and O-At enzymes which have a role in metabolic activation mechanism of nitro compunds. Conclusion: Our study showed that, 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane derivatives have no genotoxic effects in this test system. This result is a very important data making them a potential drug candidate. Key Words: Nitro compounds, umu-microplate, genotoxicity, drug Conflict of Interest: Authors have no conflict of interest. ÖZETAmaç: Bu çalışmada, ilaç etken maddesi olarak tasarlanmış altı adet nitrobütan türevinin genotoksik potansiyelleri, umu-mikroplak test sistemi ile değerlendirilmiştir. İn vitro testlerde anlamlı bir ilaç aktivitesinin saptanması durumunda, güvenlik testlerinin uygulanması, ilaç geliştirmede çok önemli bir ilkedir. Kemoterapide hastayı risk oluşturmadan tedavi etmek esas olduğundan, güvenlik testleri ilacın deneysel koşullardaki etkinliğinden bile daha fazla önem taşıyabilir. Metod: Umu-mikroplak test sistemi özel olarak nitrolu bileşiklerin mutajenitesini saptamak için tasarlanmıştır. 1-[(2-aminofenil)tiyo]-1-fenil-2-nitrobütan (I) türevleri de nitro grubu içermektedir, bu nedenle çalışmamızda bu test sistemi seçilmiştir. SOS indükleme aktivitelerinin değerlendirildiği umu-mikroplak test sisteminde, nitrolu bileşiklere hassas olarak geliştirilmiş, NR (nitroredüktaz) enzimini normalden fazla ifade e...

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Genotoxicity of potent antiviral 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane derivatives designed as drug agents

Doğan¹,

Durusoy²,

Gökçe³

et al. 2014

Turk J Bioch

View full text Add to dashboard Cite

show abstract

“…CYP2C6 and CYP2C11 have been shown to be the major enzymes responsible for the bioactivation of CP in uninduced male rat liver microsomes (25), and nitro group-containing aromatic compounds (AF-2 and 4NQO) are reported to be activated by bacterial nitroreductase enzymes (26)(27)(28). It is important that each promutagen is not merely activated by a single speciˆc metabolizing enzyme, but also activated or detoxiˆed by some other metabolizing enzymes, including enzymes of the CYP subfamily, and that the magnitude of the mutagenicity is determined by the metabolic balance between the activation and detoxiˆcation of promutagens (12,13,(18)(19)(20). These lines of evidence and knowledge suggest that the inhibitory eŠect of DMSO on the mutagenicity observed in this study may be attributable to its inhibitory eŠect on the exogenous or endogenous drug-metabolizing enzymes involved in the parallel or sequential metabolic activation/detoxiˆca-tion pathways.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, DMSO is frequently used at concentrations of as high as 14z in the Ames preincubation test, where practically no decrease of the mutagenicity of MMS has been observed in spite of its marked cytotoxicity against the TA100 and TA1535 strains among the standard bacterial test strains recommended for use in the guidelines (6). As discussed in the reports (12,13), careful consideration should be given to the metabolism of the compounds during the evaluation of the mutagenicity of test chemicals, and while maximum volumes of DMSO were recommended (100 mL/plate) for the plate incorporation assay, lower amounts/concentrations were suggested for the preincubation version of the test [for example, 31.6 mL/plate of DMSO produced little poisoning of metabolic activation for a number of promutagens, Gocke as a personal communication in reference (12)]. However, data on the eŠect of DMSO on the mutagenicity of promutagens are still limited (5,7,(14)(15)(16)(17).…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand some studies have demonstrated that DMSO inhibits several kinds of CYP enzymes involved in the metabolic activation or detoxiˆca-tion of chemical mutagens, even at concentrations of 1 z or less (7)(8)(9)(10)(11). Although the issue of poisoning of enzymes by organic vehicles, including DMSO, in genotoxicity tests has been debated (12,13), data on the eŠect of DMSO on the mutagenicity of promutagens that require metabolic activation are still limited in terms of the number of compounds tested, the kinds of chemical classes studied, and comparative data for mutagenicity obtained at low and high concentrations (14z) of DMSO (5,7,(14)(15)(16)(17). Therefore, in the present study, we examined the mutagenicity of 14 promutagens belonging to several chemical classes and a direct mutagen (as a reference compound) in the presence of DMSO at concentrations of 1z and 14z in the Ames preincubation test, and compared the results, to clarify how much the results are aŠected by DMSO.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Inhibitory Effect of Dimethyl Sulfoxide on the Mutagenicity of Promutagens in the Ames Test

Hakura

Hori²,

Uchida

et al. 2010

Genes and Environment

Self Cite

View full text Add to dashboard Cite

The eŠect of dimethyl sulfoxide (DMSO) on the mutagenicity of 14 promutagens belonging to several chemical classes and one direct mutagen as a reference compound was examined in the Ames preincubation test, to clarify how much the test results were aŠected by its inhibitory activity on metabolic enzymes. The mutagens were assayed by the preincubation method using the TA100 or WP2uvrA(pKM101) bacterial test strains in the presence of 1% and 14% DMSO (concentrations in treatment mixture) with S9 mix for 12 promutagens that are known to be activated by CYP enzymes or without S9 mix for 2 promutagens that are known to be activated by bacterial nitroreductase enzymes, and the direct-mutagen. The data indicate that the mutagenicity of 11 of the 14 promutagens was signiˆcantly reduced in the presence of 14% DMSO as compared with that in the presence of 1% DMSO, while the 3 remaining promutagens and the direct mutagen exhibited mutagenicity of equal degree at both concentrations. The largest inhibitory eŠect of DMSO was found on the nitrosamines in WP2uvrA(pKM101) and TA100, and no cytotoxicity was detected by survival test, with 14% DMSO in WP2uvrA(pKM101), at any amounts of dimethylnitrosamine. Further equivalent or slightly lower cytotoxicity in the presence of 14% DMSO than in the presence of 1% DMSO was detected by decrease in the bacterial background-lawn density, as a whole. These observations suggest that the reduction in the yield of revertant colonies in the presence of 14% DMSO with the 11 chemicals was not due to cytotoxicity of DMSO. The inhibitory eŠect of DMSO on the mutagenicity of the promutagens can be explained by its inhibitory eŠect on the drug-metabolizing enzymes involved in the activation/detoxiˆcation pathways. Use of DMSO at a low concentration, such as 1%, may be suggested for the Ames test, as for other in vitro genotoxicity tests.

show abstract

Genetic Toxicology Testing Guidelines and Regulations

Müller

Martus

2010

Cancer Risk Assessment

View full text Add to dashboard Cite

Strategy for genotoxicity testing—Metabolic considerations

Cited by 98 publications

References 56 publications

Genotoxicity of potent antiviral 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane derivatives designed as drug agents

Genotoxicity of potent antiviral 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane derivatives designed as drug agents

Inhibitory Effect of Dimethyl Sulfoxide on the Mutagenicity of Promutagens in the Ames Test

Genetic Toxicology Testing Guidelines and Regulations

Contact Info

Product

Resources

About