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Toxicological information

Genetic toxicity: in vitro

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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:
2006-09-28 to 2007-02-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study performed according to OECD Guideline 471 (Bacterial Reverse Mutation Assay) and EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria) without deviations.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Remarks:
The testing facility indicated that the protocol was followed without deviation.
Qualifier:
according to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
Remarks:
The testing facility indicated that the protocol was followed without deviation.
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
Certificate from "The Department of Health of the Government of the United Kingdom"
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: VRT-126016
- Molecular formula: not applicable
- Molecular weight: not applicable
- Smiles notation: not applicable
- InChl: not applicable
- Structural formula attached as image file: not applicable
- Substance type: no data
- Physical state: white powder
- Analytical purity: 99.8 % (area)
- Impurities:<0.1% chloride and <0.3 % (area) Z-D-Cyclohexylglycine
- Composition of test material, percentage of components: no data
- Isomers composition: no data
- Purity test date: 2006-02-02
- Lot/batch No.: batch 25719 and lot 1-4107-6-02-02
- Expiration date of the lot/batch: 2008-02
- Stability under test conditions: no data
- Storage condition of test material: room temperature
- Other: The test substance was received on 2006-09-15.

Method

Target gene:
histidine locus (S. typhimurium strains); tryptophan locus (E. coli strain)
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Details on mammalian cell type (if applicable):
Not applicable
Additional strain / cell type characteristics:
other: Please see below for additional strain characteristics.
Species / strain / cell type:
E. coli WP2 uvr A pKM 101
Details on mammalian cell type (if applicable):
Not applicable
Additional strain / cell type characteristics:
other: Please see below for additional strain characteristics.
Metabolic activation:
with and without
Metabolic activation system:
phenobarbital and 5,6-benzoflavone induced rat liver S9
Test concentrations with justification for top dose:
Experiment 1 (with and without metabolic activation for all tester strains)-5, 15, 50, 150, 500, 1500 and 5000 ug/plate
Experiment 2 (with and without metabolic activation for all tester strains)-50, 150, 500, 1500 and 5000 ug/plate
The highest concentration tested in the study (5000 ug/plate) is the standard limit concentration recommended in the regulatory guidelines that this assay followed.
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The solubility of the test substance was assessed at 50 mg/mL in water and dimethyl sulphoxide (DMSO). It was found to be insoluble in water, but soluble in DMSO. DMSO was, therefore, used as the vehicle for the study.
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
without metabolic activation

Migrated to IUCLID6: 2 ug/plate for strains TA100 and TA1535
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
without metabolic activation

Migrated to IUCLID6: 50 ug/plate for strain TA1537
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
without metabolic activation

Migrated to IUCLID6: 2 ug/plate for strain TA98
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
Remarks:
without metabolic activation

Migrated to IUCLID6: 2 ug/plate for strain WP2 uvrA (pKM101)
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene- 10 ug/plate for strain WP2 uvrA (pKM101) and 5 ug/plate for strains TA100 and TA1535
Remarks:
with metabolic activation
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
Remarks:
with metabolic activation

Migrated to IUCLID6: 5 ug/plate for strains TA98 and TA1537
Details on test system and experimental conditions:
METHOD OF APPLICATION
- experiment 1-in agar (plate incorporation); experiment 2-preincubation

DURATION
- Preincubation period: 30 minutes (experiment 2)
- Exposure duration: 72 hours (experiments 1 and 2)
- Expression time: not applicable
- Selection time: 72 hours (experiments 1 and 2); simultaneous with exposure
- Fixation time: not applicable

SELECTION AGENT
- histidine (S. typhimurium strains) and tryptophan (E. coli strain)

SPINDLE INHIBITOR
- not applicable

STAIN
- not applicable

NUMBER OF REPLICATIONS
- 3 (experiments 1 and 2)

NUMBER OF CELLS EVALUATED
- not applicable

DETERMINATION OF CYTOTOXICITY
- Method: Toxic effects of the test substance were detected by a substantial reduction in mean revertant colony counts or by a sparse or absent background bacterial lawn.

OTHER EXAMINATIONS
- Determination of polyploidy: not applicable
- Determination of endoreplication: not applicable
- Other: not applicable

OTHER
- Additional plates were prepared without the addition of bacteria, in order to assess the sterility of the test substance, S9 mix and sodium phosphate buffer. In addition, the viability of the cultures used for the experments were evaluated by adding to nutrient broth and icnucating for 10 hours. These cultures were then spread on nutrient agar for 24 hours and the resulting colonies were counted.
Evaluation criteria:
If exposure to the test substance produced a reproducible increase in revertant colony numbers of at least twice (three times in the case of strains TA1535 and TA1537) the concurrent vehicle controls, with some evidence of a positive dose-response relationship, it was considered to exhibit mutagenic activity in the test system.
If exposure to the test substance did not produce a reproducible increase in revertant colony numbers, it was considered to show no evidence of mutagenic activity in the test system.
If the results obtained failed to satisfy the criteria for a clear "positive" or "negative" response, even after additional testing, the test data, may have been subjected to analysis to determine the statistical significance of any increase in revertant colony numbers. See statistics section below. Biological importance was considered along with statistical significance. In general, treatment-associated increases in revertant colony numbers below two or three times the vehicle controls were not considered biologically important. It was acceptable to conclude an equivocal response if no clear results could be obtained.
If these criteria were not appropriate to the test data, the Study Director would use scientific judgment.
Statistics:
The mean number and standard deviation of revertant colonies were calculated for all groups. The "fold-increases" relative to the vehicle controls were calculated in order to compare the means for all treatment groups with those obtained for the vehicle control groups. No statistical analysis was performed for tests judged as negative or positive. However, if tests failed to satisfy the criteria for a clear positive or negative response and statistical tests were deemed necessary, the statistical procedures used were those described by Mahon et al (1989) and were usually Dunnett's test followed , if appropriate, by trend analysis.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Remarks:
experiment 1 and 2
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Species / strain:
E. coli WP2 uvr A pKM 101
Metabolic activation:
with and without
Genotoxicity:
negative
Remarks:
experiments 1 and 2
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no data
- Effects of osmolality: no data
- Evaporation from medium: no data
- Water solubility: The test substance was not soluble in water.
- Precipitation: no data
- Other confounding effects: no data

RANGE-FINDING/SCREENING STUDIES
No range-finding test was performed. However, experiment 1 was used to specify the concentrations to be used in experiment 2.

COMPARISON WITH HISTORICAL CONTROL DATA
The mean revertant colony counts for the vehicle control were within or close to the 99 % confidence limits of the current historical control range of the laboratory (experiments 1 and 2). Appropriate positive control substances (experiments 1 and 2) induced substantial increases (all within historical positive control range) in revertant colony numbers with all strains in all tests, confirming sensitivity of the cultures and activity of the S9 mix. No substantial increases in revertant colony numbers over control counts were obtained with any of the tester strains following exposure to the test substance at any concentration up to 5000 ug/plate in either the presence or absence of metabolic activation in either of the experiments.

ADDITIONAL INFORMATION ON CYTOTOXICITY
No evidence of toxicity was obtained following exposure to the test substance in either of the experiments.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

The absence of colonies on sterility check plates confirmed the absence of microbial contamination of the S9 mix, buffer and test substance formulation. Total colony counts on nutrient agar plates (100 uL aliquots of E-6 dilution of 10 -hour bacterial culture) confirmed the viability and high cell density of the cultures of the individual organisms.

Applicant's summary and conclusion

Conclusions:
The test substance was evaluated for mutagenic potential using the Ames assay in S. typhimurium strains TA98, TA100, TA1535, TA1537 and E. coli strain WP2 uvrA (pKM101), both in the presence and absence of metabolic activation. It was concluded that the test substance showed no evidence of mutagenic activity in this bacterial system, under the test conditions employed, up to a concentration of 5000 ug/plate.
Executive summary:

Not applicable