2-[4-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)phenyl]butyric acid

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2017-10-09 to 2017-10-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2-[4-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)phenyl]butyric acid

EC Number:

303-995-2

EC Name:

2-[4-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)phenyl]butyric acid

Cas Number:

94232-67-4

Molecular formula:

C18H15NO4

IUPAC Name:

2-[4-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)phenyl]butanoic acid

Specific details on test material used for the study:

Batch:17001R73A
Purity: 102%

Method

Target gene:

histidine locus in several strains of Salmonella typhimurium and tryptophan locus of Escherichia coli (E. coli) strain

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Rat liver metabolic activation system (S9 homogenate)

Test concentrations with justification for top dose:

-Dose-range Finding Test:
TA100 and the WP2uvrA, both with and without S9-mix: 1.7, 5.4, 17, 52, 164, 512, 1600 and 5000 μg/plate.
-First Experiment:
TA1535, TA1537 and TA98, both with and without S9-mix: 52, 164, 512, 1600 and 5000 μg/plate.
-Second Experiment:
TA1535, TA1537, TA98, TA100 and the WP2uvrA,both with and without S9-mix: 52, 164, 512, 1600 and 5000 μg/plate.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: dimethyl sulfoxide
- Justification for choice of solvent/vehicle: Through solubility test based on visual assessment, the test item was dissolved in dimethyl sulfoxide.

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

For TA1535, without metabolic activation.

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: ICR-191

Remarks:

For TA1537, without metabolic activation

Controls 3

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

For TA1537, TA98, without metabolic activation

Controls 4

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

For TA100, without metabolic activation

Controls 5

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

Remarks:

For WP2uvrA, wthout metabolic activation

Controls 6

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

For TA1535, TA1537, TA98, TA100 and WP2uvrA, with metabolic activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: Dose-Range Finding Test and Experiment 1: in agar (plate incorporation); Experiment 2: preincubation
- Cell density at seeding (if applicable): the optical density of 1.0 ± 0.1 at 700 nm (1E+09 cells/mL)

DURATION
- Preincubation period: 30 ± 2 minutes for Experiment 2.
- Exposure duration: 48 ± 4 h both for dose range finding test, Experiment 1 and Experiment 2.

DETERMINATION OF CYTOTOXICITY
- Method: To determine the toxicity of the test item, the reduction of the bacterial background lawn, the increase in the size of the microcolonies and the reduction of the revertant colonies were observed

Evaluation criteria:

A Salmonella typhimurium reverse mutation assay and/or Escherichia coli reverse mutation assay is considered acceptable if it meets the following criteria:
a) The vehicle control and positive control plates from each tester strain (with or without S9-mix) must exhibit a characteristic number of revertant colonies whencompared against relevant historical control data generated at the lab.
b) The selected dose-range should include a clearly toxic concentration or should exhibit limited solubility as demonstrated by the preliminary toxicity range-finding test or should extend to 5 mg/plate.
c) No more than 5% of the plates are lost through contamination or some other unforeseen event. If the results are considered invalid due to contamination, the xperiment will be repeated.

Statistics:

A test item is considered negative (not mutagenic) in the test if:
a) The total number of revertants in tester strain TA100 or WP2uvrA is not greater than two (2) times the concurrent control, and the total number of revertants intester strains TA1535, TA1537 or TA98 is not greater than three (3) times the concurrent 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 control, or the total number of revertants in tester strains TA1535, TA1537 or TA98 is greater than three (3) times the concurrent control.
b) In case a repeat 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.

Results and discussion

Test results

Test results 1

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

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 6

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 7

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 8

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

Positive controls validity:

valid

Additional information on results:

Dose range finding test/first mutation experiment
-Precipitate: Precipitation of the test item on the plates was not observed at the start or at the end of the incubation period.
-Toxicity: Cytotoxicity, as evidenced by a decrease in the number of revertants, was observed in the tester strains TA100, TA1537 and TA98 in the absence of S9-mix.
-Mutagenicity: In the direct plate test, no increase in the number of revertants was observed upon treatment with Phtalimido butyric acid under all conditions tested.

Second Experiment
-Precipitate: Precipitation of the test item on the plates was not observed at the start or at the end of the incubation period.
-Toxicity: There was no reduction in the bacterial background lawn and no biologically relevant decrease in the number of revertants at any of the concentrations tested in all tester strains in the absence and presence of S9-mix. In tester strain TA1537 in the presence of S9-mix, a fluctuation in the number of revertant colonies below the laboratory historical control data range was observed. However, since no dose-relationship was observed, this reduction is not considered to be caused by toxicity of the test item. It is more likely this reduction is caused by an incidental fluctuation in the number of revertant colonies.
-Mutagenicity: In the pre-incubation test, no increase in the number of revertants was observed upon treatment with the test item under all conditions tested.

Applicant's summary and conclusion

Conclusions:

The test item is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay.

Executive summary:

The potential of test item and/or its metabolites to induce reverse mutations at the histidine locus in several strains of Salmonella typhimurium (S. typhimurium; TA98, TA100, TA1535, and TA1537), and at the tryptophan locus of Escherichia coli (E. coli) strain WP2uvrA in the presence or absence of an exogenous mammalian metabolic activation system (S9) were determined according to OECD 471. 

The test was performed in two independent experiments, at first a direct plate assay was performed and secondly a pre-incubation assay.

The test item did not induce a significant dose-related increase in the number of revertant (His+) colonies in each of the four tester strains (TA1535, TA1537, TA98 and TA100) and in the number of revertant (Trp+) colonies in tester strain WP2uvrA both in the absence and presence of S9-metabolic activation. These results were confirmed in a follow-up experiment.

 

In conclusion, based on the results of this study it is concluded that test item is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay.