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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:
Experimental start date 08 June 2016. Experimental completion date 20 June 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report date:
2016

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)
Deviations:
no
Qualifier:
according to guideline
Guideline:
JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
Reaction mass of N-(3-{[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]amino}propyl)-N,N-dimethyldocosan-1-aminium chloride and N-(3-{[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]amino}propyl)-N,N-dimethylicosan-1-aminium chloride
EC Number:
947-079-6
IUPAC Name:
Reaction mass of N-(3-{[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]amino}propyl)-N,N-dimethyldocosan-1-aminium chloride and N-(3-{[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]amino}propyl)-N,N-dimethylicosan-1-aminium chloride
Test material form:
other: paste
Specific details on test material used for the study:
Identification: Methoxycinnamidopropyl Behendimonium Chloride
Physical state/Appearance: Off-white paste
Batch: INV-1603010
Purity: 29.37%
Expiry Date: 01 February 2017
Storage Conditions: Room temperature in the dark

Formulated concentrations were adjusted to allow for the stated solids content (29.37%) of the test item.

Method

Target gene:
Histidine locus
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:
Phenobarbital/ β-naphthoflavone induced rat liver S9 were used as the metabolic activation system
Test concentrations with justification for top dose:
Mutagenicity: Experiment 1: 1.5, 5, 15, 50, 150, 500, 1500 and 5000 μg/plate.
The maximum concentration was 5000 μg/plate (the maximum recommended dose level).

Mutagenicity: Experiment 2: 15, 50, 150, 500, 1500, 5000 μg/plate.
There was no visible reduction in the growth of the bacterial background lawn at any dose level, either in the presence or absence of metabolic activation (S9-mix), in the first mutation test (plate incorporation method) and consequently the same maximum dose level was used in the second mutation test.
Vehicle / solvent:
In solubility checks performed in–house the test item was noted to be insoluble in sterile distilled water, dimethyl sulphoxide, dimethyl formamide and acetonitrile at 50 mg/mL and in acetone at 100 mg/mL but was fully soluble in tetrahydrofuran at 200 mg/mL. Tetrahydrofuran was therefore selected as the vehicle.
Controlsopen allclose all
Untreated negative controls:
yes
Remarks:
sponaneous mutation rates
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Remarks:
2 μg/plate for WP2uvrA. 3 μg/plate for TA100. 5 μg/plate for TA1535.
Positive control substance:
N-ethyl-N-nitro-N-nitrosoguanidine
Remarks:
without metabolic activation
Untreated negative controls:
yes
Remarks:
sponaneous mutation rates
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Remarks:
80 μg/plate for TA1537
Positive control substance:
9-aminoacridine
Remarks:
without metabolic activation
Untreated negative controls:
yes
Remarks:
sponaneous mutation rates
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Remarks:
0.2 μg/plate for TA98
Positive control substance:
4-nitroquinoline-N-oxide
Remarks:
without metabolic activation
Untreated negative controls:
yes
Remarks:
sponaneous mutation rates
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Remarks:
1 μg/plate for TA100. 2 μg/plate for TA1535 and TA1537. 10 μg/plate for WP2uvrA.
Positive control substance:
other: 2-Aminoanthracene (2AA)
Remarks:
with metabolic activation
Untreated negative controls:
yes
Remarks:
sponaneous mutation rates
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Remarks:
5 μg/plate for TA98
Positive control substance:
benzo(a)pyrene
Remarks:
with metabolic activation
Details on test system and experimental conditions:
Test Item Preparation and Analysis:
The test item was accurately weighed and approximate half-log dilutions prepared in tetrahydrofuran by mixing on a vortex mixer and sonication for 20 minutes at 40 °C on the day of each experiment. Formulated concentrations were adjusted to allow for the stated solids content (29.37%) of the test item. Tetrahydrofuran is toxic to the bacterial cells at and above 50 μL (0.05 mL), therefore all of the formulations were prepared at concentrations four times greater than required on Vogel-Bonner agar plates. To compensate, each formulation was dosed using 25 μL (0.025 mL) aliquots. Tetrahydrofuran is considered an acceptable vehicle for use in this test system (Maron et al., 1981). Prior to use, the solvent was dried to remove water using molecular sieves i.e. 2 mm sodium alumino-silicate pellets with a
nominal pore diameter of 4 x 10^-4 microns.
All formulations were used within four hours of preparation and were assumed to be stable for this period. Analysis for concentration, homogeneity and stability of the test item formulations is not a requirement of the test guidelines and was, therefore, not determined.

Test for Mutagenicity: Experiment 1 - Plate Incorporation Method:
Without Metabolic Activation:
0.025 mL of the appropriate concentration of test item or solvent vehicle or 0.1 mL of appropriate positive control was added to 2 mL of molten, trace amino-acid supplemented media containing 0.1 mL of one of the bacterial strain cultures and 0.5 mL of phosphate buffer. These were then mixed and overlayed onto a Vogel-Bonner agar plate. Negative (untreated) controls were also performed on the same day as the mutation test. Each concentration of the test item, appropriate positive, vehicle and negative controls, and each bacterial strain, was assayed using triplicate plates.

With Metabolic Activation:
The procedure was the same as described previously except that following the addition of the test item formulation and bacterial culture, 0.5 mL of S9-mix was added to the molten, trace amino-acid supplemented media instead of phosphate buffer.

Incubation and Scoring:
All of the plates were incubated at 37 ± 3 °C for approximately 48 hours and scored for the presence of revertant colonies using an automated colony counting system. The plates were viewed microscopically for evidence of thinning (toxicity). Manual counts were performed at and above 1500 μg/plate because of test item precipitation. Several further manual counts were also required due to marks on the base plate and interference in the base agar e.g. minor precipitation of salts/dust particles slightly distorting the counts.

Test for Mutagenicity: Experiment 2 – Pre-Incubation Method:
As Experiment 1 was deemed negative, Experiment 2 was performed using the pre-incubation method in the presence and absence of metabolic activation.

Dose selection:
The dose range used for Experiment 2 was determined by the results of Experiment 1 and was 15 to 5000 μg/plate.
Six test item dose levels were selected in Experiment 2 in order to achieve both a minimum of four non-toxic dose levels and the toxic limit of the test item following the change in test methodology from plate incorporation to pre-incubation.

Without Metabolic Activation:
0.1 mL of the appropriate bacterial strain culture, 0.5 mL of phosphate buffer and 0.025 mL of the test item formulation or solvent vehicle or 0.1 mL of appropriate positive control were incubated at 37 ± 3 °C for 20 minutes (with shaking) prior to addition of 2 mL of molten, trace amino-acid supplemented media and subsequent plating onto Vogel-Bonner plates. Negative (untreated) controls were also performed on the same day as the mutation test employing the plate incorporation method. All testing for this experiment was performed in triplicate.

With Metabolic Activation:
The procedure was the same as described previously except that following the addition of the test item formulation and bacterial strain culture, 0.5 mL of S9-mix was added to the tube instead of phosphate buffer, prior to incubation at 37 ± 3 °C for 20 minutes (with shaking) and addition of molten, trace amino-acid supplemented media. All testing for this experiment was performed in triplicate.

Incubation and Scoring:
All of the plates were incubated at 37 ± 3 °C for approximately 48 hours and scored for the presence of revertant colonies using an automated colony counting system. The plates were viewed microscopically for evidence of thinning (toxicity). Manual counts were performed at and above 1500 μg/plate because of test item precipitation. Further manual counts were also required due to marks on the base plate and interference in the base agar e.g. minor precipitation of salts/dust particles slightly distorting the counts. Occasional plates were also manually assessed for accuracy against the automated counts.
Evaluation criteria:
There are several criteria for determining a positive result. Any, one, or all of the following can be used to determine the overall result of the study:
1. A dose-related increase in mutant frequency over the dose range tested (De Serres and Shelby, 1979).
2. A reproducible increase at one or more concentrations.
3. Biological relevance against in-house historical control ranges.
4. Statistical analysis of data as determined by UKEMS (Mahon et al., 1989).
5. Fold increase greater than two times the concurrent solvent control for any tester strain (especially if accompanied by an out-of-historical range response (Cariello and Piegorsch, 1996)).
A test item will be considered non-mutagenic (negative) in the test system if the above criteria are not met. Although most experiments will give clear positive or negative results, in some instances the data generated will prohibit making a definite judgment about test item activity. Results of this type will be reported as equivocal.
Statistics:
Statistical significance was confirmed by using Dunnetts Regression Analysis (* = p < 0.05) for those values that indicate statistically significant increases in the frequency of revertant colonies compared to the concurrent solvent control.

Results and discussion

Test resultsopen allclose all
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:
valid
Positive controls validity:
valid
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:
valid
Positive controls validity:
valid
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:
valid
Positive controls validity:
valid
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:
valid
Positive controls validity:
valid
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:
valid
Positive controls validity:
valid
Additional information on results:
Prior to use, the master strains were checked for characteristics, viability and spontaneous reversion rate (all were found to be satisfactory). The amino acid supplemented top agar and the S9-mix used in both experiments was shown to be sterile. The test item formulation was also shown to be sterile.

Results for the negative controls (spontaneous mutation rates) and were considered to be acceptable. These data are for concurrent untreated control plates performed on the same day as the Mutation Test.

The maximum dose level of the test item in the first experiment was selected as the maximum recommended dose level of 5000 μg/plate. There was no visible reduction in the growth of the bacterial background lawn at any dose level, either in the presence or absence of metabolic activation (S9-mix), in the first mutation test (plate incorporation method) and consequently the same maximum dose level was used in the second mutation test. Similarly there was no visible reduction in the growth of the bacterial background lawn at any dose level, either in the presence or absence of metabolic activation (S9-mix), in the second mutation test (pre-incubation method). A test item precipitate (white and powdery in appearance) was noted from 1500 μg/plate (Experiment 1; plate incorporation method) and from 500 μg/plate (Experiment 2; pre-incubation method). These precipitate observations did not prevent the scoring of revertant colonies.

There were no toxicologically significant increases in the frequency of revertant colonies recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation (S9-mix) in Experiment 1 (plate incorporation method). Similarly, no significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation (S9-mix) in Experiment 2 (pre-incubation method). A small, statistically significant increase in TA1535 revertant colony frequency was observed in the presence of S9-mix at
150 μg/plate in the first mutation test. This increase was considered to be of no biological relevance because there was no evidence of a dose-response relationship or reproducibility. Furthermore, the individual revertant colony counts at 150 μg/plate were within the in-house historical untreated/vehicle control range for the tester strain and the fold increase was only 1.7 times the concurrent vehicle control.

The vehicle (tetrahydrofuran) control plates gave counts of revertant colonies generally within the normal range. A single count for TA1535 (presence of S9-mix during the first mutation test) was just below the minimum level. This count was still considered acceptable as the other vehicle and untreated control counts were within expected range and the tester strain responded very well with the respective positive controls in both the presence and absence of S9-mix. All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies, both with or without metabolic activation.
Thus, the sensitivity of the assay and the efficacy of the S9-mix were validated.

Applicant's summary and conclusion

Conclusions:
Methoxycinnamidopropyl Behendimonium Chloride was considered to be non-mutagenic under the conditions of this test.
Executive summary:

Introduction

The test method was designed to be compatible with the guidelines for bacterial mutagenicity testing published by the major Japanese Regulatory Authorities including METI, MHLW and MAFF, the OECD Guidelines for Testing of Chemicals No. 471 "Bacterial Reverse Mutation Test", Method B13/14 of Commission Regulation (EC) number 440/2008 of 30 May 2008 and the USA, EPA OCSPP harmonized guideline - Bacterial Reverse Mutation Test.

Methods

Salmonella typhimurium strains TA1535, TA1537, TA98 and TA100 and Escherichia coli strain WP2uvrA were treated with the test item using both the Ames plate incorporation and pre-incubation methods at up to eight dose levels, in triplicate, both with and without the addition of a rat liver homogenate metabolizing system (10% liver S9 in standard co-factors). The dose range for Experiment 1 was predetermined and was 1.5 to 5000 μg/plate. The experiment was repeated on a separate day (pre-incubation method) using fresh cultures of the bacterial strains and fresh test item formulations. The dose range was amended following the results of Experiment 1 and was 15 to 5000 μg/plate.

Six test item concentrations were selected in Experiment 2 in order to achieve both four non-toxic dose levels and the potential toxic limit of the test item following the change in test methodology.

Results

The vehicle (tetrahydrofuran) control plates gave counts of revertant colonies generally within the normal range. All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies, both with or without metabolic activation. Thus, the sensitivity of the assay and the efficacy of the S9-mix were validated.

The maximum dose level of the test item in the first experiment was selected as the maximum recommended dose level of 5000 μg/plate. There was no visible reduction in the growth of the bacterial background lawn at any dose level, either in the presence or absence of metabolic activation (S9-mix), in the first mutation test (plate incorporation method) and consequently the same maximum dose level was used in the second mutation test. Similarly there was no visible reduction in the growth of the bacterial background lawn at any dose level, either in the presence or absence of metabolic activation (S9-mix), in the second mutation test (pre-incubation method). A test item precipitate (white and powdery in appearance) was noted from 1500 μg/plate (Experiment 1; plate incorporation method) and from 500 μg/plate (Experiment 2; pre-incubation method). These precipitate observations did not prevent the scoring of revertant colonies.

There were no toxicologically significant increases in the frequency of revertant colonies recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation (S9-mix) in Experiment 1 (plate incorporation method). Similarly, no significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test item, either with or without metabolic activation (S9-mix) in Experiment 2 (pre-incubation method). A small, statistically significant increase in TA1535 revertant colony frequency was observed in the presence of S9-mix at 150 μg/plate in the first mutation test. This increase was considered to be of no biological relevance because there was no evidence of a dose-response relationship or reproducibility. Furthermore, the individual revertant colony counts at 150 μg/plate were within the in-house historical untreated/vehicle control range for the tester strain and the fold increase was only 1.7 times the concurrent vehicle control.

Conclusion

Methoxycinnamidopropyl Behendimonium Chloride was considered to be non-mutagenic under the conditions of this test.

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