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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Apr 1991 - June 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report date:
1991

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Qualifier:
according to guideline
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Qualifier:
according to guideline
Guideline:
JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
Qualifier:
according to guideline
Guideline:
EPA OTS 798.5265 (The Salmonella typhimurium Bacterial Reverse Mutation Test)
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
N-Pentanoyl-N-{[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl}-L-valine
EC Number:
604-045-2
Cas Number:
137862-53-4
Molecular formula:
C24 H29 N5 O3
IUPAC Name:
N-Pentanoyl-N-{[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl}-L-valine
Test material form:
solid: particulate/powder

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
Rat-liver microsomal fraction S9 was prepared in advance from male RAI rats
Test concentrations with justification for top dose:
The concentration range of CGP 48933 to be tested in the mutagenicity test was determined in a preliminary toxicity test. Thus, CGP 48933 was tested for mutagenic effects without microsomal activation at five concentrations in the range of 312.5 - 5000 μg/plate. In the experiment carried out with microsomal activation five concentrations in the range of 312.5 - 5000 μg/plate were tested. In order to confirm the results, the experiments were repeated with the same concentration ranges.
Six concentrations of CGP 48933 ranging from 20. 6-5000 μg/plate were tested with strains s. typhimurium TA 100 and E.coli WP2uvrA to determine the highest concentration to be used in the mutagenicity assay. The experiments were performed with and without microsomal activation. From the results obtained, the highest concentration suitable for the mutagenicity test was selected to be 5000 μg/plate without and with microsomal activation.
Vehicle / solvent:
CGP 48933 was dissolved in dimethylsulfoxide at room temperature.
The highest concentration of CGP 48933 was determined in a preliminary solubilisation test to be so mg/ml. Lower concentrations of the test substance were obtained by-appropriate dilution of the stock solution with dimethylsulfoxide. No precipitates or aggregates were noted.
Details on test system and experimental conditions:
This test system permits the detection of gene mutations induced by the test material or its metabolites in histidine-requiring strains of Salmonella typhimurium and in a tryptophan-requiring strain of Escherichia coli. When the Salmonella strains are exposed to a mutagen, some of the bacteria in the treated population, through chemical interaction with the compound, undergo genetic changes which cause them to revert to a non-histidine-requiring state and thus to grow in the
absence of exogenous histidine. Similarly, after mutation, the E.coli bacteria are able to grow in tryptophan-free medium. Mutagenic effects of the test ubstance are demonstrable on comparison of the number of bacteria in the treated and control cultures that have undergone reverse-mutation to histidine prototrophism or tryptophan prototrophism, respectively. Different tester strains are used because of differing sensitivities to known mutagens. The following bacterial
strains have been used in this study:
Strain Type of Mutation
s. typhimurium TA 100 b ase-pair substitution
s. typhimurium TA 1535 base-pair substitution
E. coli WP2uvrA base-pair substitution
s. typhimurium TA 98 frame-shift
s. typhimurium TA 1537 frame-shift
Rationale for test conditions:
The concentration range of CGP 48933 to be tested in the mutagenicity test was determined in a preliminary toxicity test.
Statistics:
A statistical analysis was not performed. At present the use of statistical methods concerning this particular test system is not generally recommended

Results and discussion

Test results
Key result
Species / strain:
S. typhimurium, other: TA 98, TA 100, TA 1535 and TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
True negative controls validity:
not applicable
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
Based on the results of these experiments and on standard evaluation criteria, it is concluded that CGP 48933 and its metabolites did not induce gene mutations in the strains of S. typhimurium and E.coli used.