4-Ethoxy-2,3-difluorphenylboronic 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:

2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Screening assay (only results were reported, limited number of strains, methodological details are missing)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not applicable

GLP compliance:

no

Remarks:

Screening test

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

(4-ethoxy-2,3-difluorophenyl)boronic acid

EC Number:

606-729-6

Cas Number:

212386-71-5

Molecular formula:

C8 H9 B F2 O3

IUPAC Name:

(4-ethoxy-2,3-difluorophenyl)boronic acid

Test material form:

solid

Method

Target gene:

HIS operon (S. thyphimurium)
TRP operon (E. coli)

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 98

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 100

Species / strain 3

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Liver S9 mix from Aroclor 1254-pretreated rats with standard co-factors

Test concentrations with justification for top dose:

1st series (TA 98, TA 100, E. coli WP2 uvr A): 5, 15.8, 50, 158, 500, 500, 1580 and 5000 μg/plate
2nd series (TA 100, E. coli WP2 uvr A): 500, 889, 1580, and 2810 μg/plate

Vehicle / solvent:

DMSO

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

sodium azide

other: daunomycin

Remarks:

without S9 mix

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

with S9 mix

Details on test system and experimental conditions:

The assessment of test material-induced effects is dependent on the number of spontaneous revertants of each bacterial strain (solvent controls) and the increase in the number of revertants at the test material concentration which shows the highest number of colonies.

Rationale for test conditions:

Screening assay

Statistics:

n.a.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

reduced background lawn at 5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

reduced background lawn at 5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

reduced background lawn at 5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation and time of the determination: Precipitation at the beginning of the experiment starting at 1580 µg/plate.

Ames test:
- Signs of toxicity : Reduced bacterial background lawn at 5000 µg/plate in all three strains.

Applicant's summary and conclusion

Conclusions:

With and without addition of S9 mix as the external metabolizing system, the test item was mutagenic in Salmonella typhimurium TA 100 and Escherichia coli WP2 uvrA under the experimental conditions described.

Executive summary:

Study design

The mutagenic potential of the test item was examined in a screening assay equivalent to OECD GL 471 using Salmonella typhimurium tester strains TA 98, TA 100 and Escherichia coli WP2 uvrA. The plate incorporation test (two parallel plates per condition) with and without addition of liver S9 mix from Aroclor 1254-pretreated rats was used. The test item was dissolved in DMSO and tested at concentrations ranging from 5 - 5000 μg/plate.

Results

Precipitation of the test item on the agar plates occurred at concentrations of >= 1580 μg/plate and toxicity to bacteria at 5000 µg/plate. The treatment with the test materials used as positive controls led to a clear increase in revertant colonies, thus, showing the expected reversion properties of all strains and good metabolic activity of the S9 mix used. Following test item treatments in the absence and presence of S9, the test item was mutagenic in Salmonella typhimurium TA 100 and Escherichia coli WP2 uvrA.

Conclusion

With and without addition of S9 mix as the external metabolizing system, the test item was mutagenic in Salmonella typhimurium TA 100 and Escherichia coli WP2 uvrA.