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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:
2016-04-04 to 2016-04-13
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:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Details on test material:
- Name of test material (as cited in study reports): JNJ-118872-AAA (T000749)
- Physical state: liquid
- Appearance: Light yellow, light brown liquid
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: A15JB2997
- Expiration date of the lot/batch: 2016-10-21
- Purity test date: 2015-10-22

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
- Stability under test conditions:not indicated
- Solubility and stability of the test substance in the solvent/vehicle: not indicated
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: not indicated

Method

Target gene:
The Histidine locus (S. typhimurium strains TA98, TA100, TA1535 and TA1537) and the Tryptophan locus (E. coli).
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Details on mammalian cell type (if applicable):
not applicable
Metabolic activation:
with and without
Metabolic activation system:
S9-mix (Aroclor 1254 induced rat liver metabolic activation system)
Test concentrations with justification for top dose:
Dose-range finding test (part 1): 1.7, 5.4, 17, 52, 164, 512, 1600 and 5000 μg/plate (top dose selected based on the solubility findings)
Mutation experiment (part 2): 52, 164, 512, 1600, 3000 and 5000 μg/plate (top dose selected based on the dose-range finding test results)


Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: In DMSO, the test item was soluble at 50 mg/ml. Based on these solubility findings, DMSO was selected as vehicle and 5000 μg/plate was selected as the maximum final concentration for the dose range finding test.
Controlsopen allclose all
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
Without metabolic activation, 5 μg/plate (TA1535)
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: ICR-191
Remarks:
Without metabolic activation, 2.5 μg/plate (TA1537)
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
Without metabolic activation, 10 μg/plate (TA98), dissolved in DMSO
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
Without metabolic activation, 650 μg/plate (TA100), dissolved in DMSO
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
Remarks:
Without metabolic activation, 10 μg/plate (WP2uvrA), dissolved in DMSO
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene
Remarks:
With S9-mix; 2.5μg/plate (TA1535 with 5 and 10% S9-mix, TA1537 with 5% S9-mix), 5μg/plate (TA1537 with 10% S9-mix), 1μg/plate (TA98 with 5 and 10% S9-mix, TA100 with 5% S9-mix), 2μg/plate (TA100 with 10% S9-mix), 15μg/plate (WP2uvrA with 5 and 10% S9-mix)
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)
Top agar in top agar tubes was melted by heating to 45 ± 2°C. The following solutions were successively added to 3 ml molten top agar: 0.1 ml of a fresh bacterial culture (10^9 cells/ml) of one of the tester strains, 0.1 ml of a dilution of the test item in DMSO and either 0.5 ml S9-mix (in case of activation assays) or 0.5 ml 0.1 M phosphate buffer (in case of non-activation assays). The ingredients were mixed on a Vortex and the content of the top agar tube was poured onto a selective agar plate. After solidification of the top agar, the plates were inverted and incubated in the dark at 37.0 ± 1.0 °C for 48 ± 4 h. After this period revertant colonies were counted.

DURATION
- Exposure duration:48+-4h
- Selection time: 48h (simultaneous with exposure)

SELECTION AGENT (mutation assays): Histidine (S. Typhimurium strains), Tryptophan (E. coli strains)

NUMBER OF REPLICATIONS: All concentrations for all experiments were tested in triplicate

DETERMINATION OF CYTOTOXICITY
- Method: Reduction in bacterial background lawn; increase in size of the microcolonies; reduction of revertant colonies
Evaluation criteria:
A test item is considered negative (not mutagenic) in the test if:
a) The total number of revertants in the tester strain TA100 or WP2uvrA is not greater than two (2) times the concurrent vehicle control, and the total number of revertants in tester strains TA1535, TA1537 or TA98 is not greater than three (3) times the concurrent vehicle control.
b) The negative response should be reproducible in at least one follow-up experiment.

A test item is considered positive (mutagenic) in the test if:
a) The total number of revertants in tester strain TA100 or WP2uvrA is greater than two (2) times the concurrent vehicle control, or the total number of revertants in tester strain TA1535, TA1537 or TA98 is greater than three (3) times the concurrent vehicle control.
b) A concentration related effect is observed.
c) In case a follow up experiment is performed when a positive response is observed in one of the tester strains, the positive response should be reproducible in at least one follow up experiment.
Statistics:
No formal hypothesis testing was done.
In addition to the criteria for a positive or negative response, any increase in the total number of revertants was evaluated for its biological relevance including a comparison of the results with the historical control data range.

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:
cytotoxicity
Remarks:
at 3000 and 5000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with
Genotoxicity:
positive
Remarks:
up to 7.0-fold increases
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 3000 and 5000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
without
Genotoxicity:
positive
Remarks:
up to 5.8-fold increases
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 3000 and 5000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with
Genotoxicity:
positive
Remarks:
up to 5.6-fold increases
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 3000 and 5000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
without
Genotoxicity:
positive
Remarks:
up to 6.6-fold increases
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 3000 and 5000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with
Genotoxicity:
positive
Remarks:
up to 3.8-fold increases
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 5000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
without
Genotoxicity:
positive
Remarks:
up to 2.8-fold increases
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 5000 µg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with
Genotoxicity:
positive
Remarks:
up to 2.3-fold increases
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:
without
Genotoxicity:
positive
Remarks:
up to 4.1-fold increases
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Water solubility: The test item was observed to be insoluble in water at 50 mg/ml (test item formed droplets in water)
- Precipitation: At 512 µg/plate and upwards (Dose-range finding test); at 512 µg/plate and upwards (Mutation experiment, start of the incubation period); at 1600 µg/plate and above (Mutation experiment; end of the incubation period)

RANGE-FINDING/SCREENING STUDIES: The test item was tested in the tester strains TA100 and WP2uvrA at concentrations of 1.7, 5.4, 17, 52, 164, 512, 1600 and 5000 μg/plate in the absence and presence of 5% (v/v) S9-mix. Based on the results, the results of the dose range finding test are reported as a part of the mutation experiment. In the second part of the mutation experiment, the test item was tested both in the absence and presence of 5% (v/v) S9-mix in the tester strains TA1535, TA1537 and TA98. Six concentrations, 52, 164, 512, 1600, 3000 and 5000 μg/plate were tested in triplicate. In compliance with the OECD guideline No 471, there is no requirement for verification of a clear positive response. Since the test results of the mutation experiment showed clear positive responses, the follow-up experiment was not performed.

HISTORICAL CONTROL DATA (with ranges, means and standard deviation and confidence interval (e.g. 95%)
- Positive historical control data: The strain-specific positive control values were within the laboratory historical control data ranges
- Negative (solvent/vehicle) historical control data: The negative control values were within the laboratory historical control data ranges

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- Measurement of cytotoxicity used: Reduction in bacterial background lawn; increase in size of the microcolonies; reduction of revertant colonies
- Other observations when applicable: Cytotoxicity was observed in the tester strains TA100, TA1535, TA1537 and TA98 in the absence and presence of S9-mix at the concentrations of 3000 and 5000 μg/plate. In tester strain WP2uvrA, no toxicity was observed at any of the dose levels tested.

Any other information on results incl. tables

Although some increases were only observed at cytotoxic or precipitating dose levels or the number of revertants were within the historical control data ranges, clear dose related increases were observed in tester strains TA98 and TA100 both in the absence and presence of S9-mix.

Applicant's summary and conclusion

Conclusions:
Interpretation of results:
positive with and without metabolic activation

Based on the results of this study it is concluded that the test item is mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay.