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EC number: 204-145-2 | CAS number: 116-53-0
Genetic toxicity: in vitro
Administrative data
- Endpoint:
- in vitro gene mutation study in bacteria
- Remarks:
- Type of genotoxicity: gene mutation
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 15. Aug 2017 to 30. Aug. 2017
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 2 017
- Report date:
- 2017
Materials and methods
Test guidelineopen allclose all
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 471 (Bacterial Reverse Mutation Assay)
- Version / remarks:
- July 21, 1997
- Qualifier:
- according to guideline
- Guideline:
- EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
- Version / remarks:
- May 30, 2008
- GLP compliance:
- yes
- Type of assay:
- bacterial reverse mutation assay
Test material
- Reference substance name:
- 2-methylbutyric acid
- EC Number:
- 204-145-2
- EC Name:
- 2-methylbutyric acid
- Cas Number:
- 116-53-0
- Molecular formula:
- C5H10O2
- IUPAC Name:
- 2-methylbutanoic acid
- Test material form:
- liquid
Constituent 1
Method
Species / strainopen allclose all
- Species / strain / cell type:
- S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
- Additional strain / cell type characteristics:
- not applicable
- Species / strain / cell type:
- E. coli WP2 uvr A
- Additional strain / cell type characteristics:
- not applicable
- Metabolic activation:
- with and without
- Metabolic activation system:
- Phenobarbital/β-naphthoflavone induced rat liver S9
- Test concentrations with justification for top dose:
- Pre-Experiment/Experiment I: 3; 10; 33; 100; 333; 1000; 2500; and 5000 μg/plate
Experiment II: 33; 100; 333; 1000; 2500; and 5000 μg/plate
Top dose according to guideline - Vehicle / solvent:
- DMSO (purity > 99%)
Controlsopen allclose all
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: TA 1535, TA 100: sodium azide, TA 1537, TA 98: 4-nitro-o-phenylene-diamine, WP2 uvrA: methyl methane sulfonate
- Remarks:
- without metabolic activation
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: 2-aminoanthracene
- Remarks:
- all strains with metabolic activation
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: plate incorporation test (experiment I) and the pre-incubation test (experiment II)
DURATION
- Preincubation period: at 37 °C for 60 minutes (experiment II)
- Exposure duration: at least 48 h
NUMBER OF REPLICATIONS: triplicates for each dose
DETERMINATION OF CYTOTOXICITY
- Method: relative total growth (background growth) - Rationale for test conditions:
- Conditions according to guideline
- Evaluation criteria:
- A test item is considered as a mutagen if a biologically relevant increase in the number of revertants exceeding the threshold of twice (strains TA 98, TA 100, and WP2 uvrA) or thrice (strains TA 1535 and TA 1537) the colony count of the corresponding solvent control is observed.
A dose dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration.
An increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent second experiment.
A dose dependent increase in the number of revertant colonies below the threshold is regarded as an indication of a mutagenic potential if reproduced in an independent second experiment. However, whenever the colony counts remain within the historical range of negative and solvent controls such an increase is not considered biologically relevant. - Statistics:
- not perfrormed
Results and discussion
Test resultsopen allclose all
- Key result
- Species / strain:
- S. typhimurium TA 1535
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium 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 examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium TA 98
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium TA 100
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- E. coli WP2 uvr A
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Additional information on results:
- No precipitation of the test item occurred up to the highest investigated dose.
Applicant's summary and conclusion
- Conclusions:
- Under the conditions of this bacterial mutagenicity assay, the test item was not mutagenic
- Executive summary:
This study was performed to investigate the potential of 2-methylbutyric acid to induce gene mutations according to the plate incorporation test (experiment I) and the pre-incubation test (experiment II) using the Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100, and the Escherichia coli strain WP2 uvrA.
The assay was performed in two independent experiments both with and without liver microsomal activation. Each concentration, including the controls, was tested in triplicate. The test item was tested at the following concentrations:
Pre-Experiment/Experiment I: 3; 10; 33; 100; 333; 1000; 2500; and 5000 μg/plate
Experiment II: 33; 100; 333; 1000; 2500; and 5000 μg/plate
No precipitation of the test item occurred up to the highest investigated dose.
The plates incubated with the test item showed normal background growth up to 5000 μg/plate with and without S9 mix in all strains used.
No toxic effects, evident as a reduction in the number of revertants (below the indication factor of 0.5), occurred in all strains with and without metabolic activation.
No substantial increase in revertant colony numbers of any of the five tester strains was observed following treatment with 2-methylbutyric acid at any dose level, neither in the presence nor absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance.
Appropriate reference mutagens were used as positive controls and showed a distinct increase of induced revertant colonies.
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