N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-2-[(2-methoxyphenyl)azo]-3-oxobutyramide

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

GLP compliance:

yes (incl. QA statement)

Type of assay:

other: In vitro mammalian cell gene mutation test using the Hprt gene

Test material

Test material information

Constituent 1

Reference substance name:

N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-2-[(2-methoxyphenyl)azo]-3-oxobutyramide

EC Number:

279-914-9

EC Name:

N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-2-[(2-methoxyphenyl)azo]-3-oxobutyramide

Cas Number:

82199-12-0

Molecular formula:

C18H17N5O4

IUPAC Name:

2-[(1E)-2-(2-methoxyphenyl)diazen-1-yl]-3-oxo-N-(2-oxo-2,3-dihydro-1H-1,3-benzodiazol-5-yl)butanamide

Test material form:

solid: bulk

Method

Target gene:

HPRT

Species / strain

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

Chinese Hamster (Cricetulus griseus) ovary cell line CHO-K1,
(ATCC CCL-61, Lot 4765275)

Metabolic activation:

with and without

Controls

Untreated negative controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

3-methylcholanthrene

Details on test system and experimental conditions:

Cells were grown in tissue culture flasks at 37 ± 1 °C in a humidified carbon dioxide incubator (5 ± 0.2 % CO2 in air)

Rationale for test conditions:

Test approaches currently accepted under the OECD for the assessment of mammalian cell gene mutation involve the use of Chinese Hamster Ovary (CHO) cell line. This cell line has been demonstrated to be sensitive to the mutagenic activity of a variety of chemicals.

Established CHO cell line is useful in in vitro gene mutation testing because it is easily cultured in standard medium, has a small number of large chromosomes each with a more or less distinctive morphology and a relatively short cycle time

Evaluation criteria:

CRITERIA FOR ACCEPTABILITY OF THE TEST
The assay will be considered valid if the following criteria are met:
a) The concurrent vehicle control data is within the range of the laboratory historical control data.
b) The concurrent positive control substances should induce responses that are compatible with those generated in the historical positive control data base and produce a statistically significant increase compared with the concurrent vehicle control.
c) Two experimental conditions are tested unless one results in positive response.
d) Adequate number of cells and analyzable concentrations are tested under each of the experimental conditions.
e) The criteria for the selection of top concentration are consistent with those described in the guideline.

EVALUATION AND INTERPRETATION OF RESULTS
When all the validity criteria are fulfilled:

1. A test chemical is considered to be clearly positive if, in any of the experimental conditions examined:
• At least one of the test concentrations exhibits a statistically significant increase compared with the concurrent vehicle control
• The increase is concentration-dependent when evaluated with an appropriate trend test
• Any of the results are outside the distribution of the historical vehicle control data

When all of these criteria are met, the test chemical is then considered able to induce gene mutations in cultured mammalian cells in this test system.

2 A test chemical is considered to be clearly negative if, in all experimental conditions examined:

• None of the test concentrations exhibits a statistically significant increase compared with the concurrent vehicle control
• There is no concentration-related increase when evaluated with an appropriate trend test
• All results are inside the distribution of the historical vehicle control data

The test chemical is then considered unable to induce gene mutations in cultured mammalian cells in this test system.

Results and discussion

Test results

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

It is concluded that the test item, C.I.Pigment Yellow 194 does not have the potential to induce gene mutation in CHO-K1 cells at the tested concentrations and under the conditions of testing employed.

Executive summary:

 

The genotoxic potential of the test item C.I.Pigment Yellow 194 induce gene mutation in mammalian cells was evaluated using Chinese Hamster ovary (CHO) cells.

 

The study consisted of a preliminary cytotoxicity test and a definitive gene mutation test. The gene mutation test comprised of two independent experiments, one each in the presence and absence of metabolic activation system (S9 fraction prepared from Aroclor 1254 induced rat liver).

 

C.I.Pigment Yellow 194 was insoluble in sterile water and formed a free flowing suspension in Dimethyl sulfoxide (DMSO) at
200 mg/mL.

 

In a preliminary cytotoxicity test for the selection of test concentrations for the gene mutation assay, the Relative Survival was 27 and 32 % at the
1000 µg/mL, in the presence and absence of metabolic activation, respectively. There was precipitation of the test item in the test medium at and above
1000 µg/mL, both in the presence and absence of metabolic activation. There was no appreciable change in the pH and osmolality of test medium. Based on these observations a maximum of 1500 µg/mL was tested in the gene mutation assay. 

 

In the gene mutation test, CHO-K1 cells were exposed to the test item in duplicate at concentrations of 23.44, 93.75, 375 and 1500 µg/mL of the medium for 3 hours in the presence (Experiment 1) and absence (Experiment 2) of metabolic activation. In a similar way, a concurrent vehicle control (DMSO) and a positive control, 3-methylcholanthrene (Experiment 1) were also tested in duplicate.

 

There was no evidence of induction of gene mutations in any of the test item treated cultures either in the presence or absence of metabolic activation. The positive control in experiment 1 produced a statistically significant increase in the frequencies of mutants, under identical conditions.

 

The results of the forward gene mutation test at thehprtlocus with C.I.Pigment Yellow 194 indicated that the test item was non-mutagenic under the conditions of this study