Pregn-4-ene-3,20-dione, 21-(acetyloxy)-6-fluoro-16-methyl-, (6.alpha.,16.alpha.)-

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

other information

Study period:

Jan to Feb 1997

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: comparable to guideline study with acceptable restrictions (no E. coli WP2 or S. typhimurium TA102 strain tested)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

- no E. coli WP2 or S. typhimurium TA102 strain tested; only one experiment (direct plate incorporation procedure) was performed

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

21-Acetoxy-6 alpha-fluoro-16 alpha-methyl-4-pregnene-3,20-dione

EC Number:

603-033-4

Cas Number:

1251-28-1

Molecular formula:

C24 H33 F O4

IUPAC Name:

21-Acetoxy-6 alpha-fluoro-16 alpha-methyl-4-pregnene-3,20-dione

Method

Target gene:

Histidine gene locus

Species / strain

Species / strain / cell type:

S. typhimurium, other: TA 98, TA 100, TA 1535, TA 1537 and TA 1538

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced male rat liver S9 mix

Test concentrations with justification for top dose:

50, 100, 250, 500, 1000, 2500 µg/plate

Vehicle / solvent:

DMSO

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 9-acridinamine, hydrochloride (only TA 1537), 2-nitrofluorene (only TA 1538 and 98), sodium azide (only TA 1535 and 100), benzo(a)pyrene (only TA 1537,1538, 98 and 100), cyclophosphamide (only TA 1535), 2-aminoanthracene (all strains)

Results and discussion

Test results

Species / strain:

S. typhimurium, other: TA 98, TA 100, TA 1535, TA 1537 and TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

The counts recorded on appropriate negative control plates confirmed the characteristically spontaneous reversion rates of the tester strains. The total colony counts of the 10 ^-6 dilution of bacterial culture confirmed the viability and high cell density of the cultures of the individual strains.

Appropriate positive control chemicals induced marked increases in revertant colony numbers with all strains.

None of the five tester strains showed increased reversion to prototrophy in assays with ZK 4841 at the concentrations tested between 50 and 2500 µg/plate, either in the absence or precence of S9 mix.

Growth inhibition of the background lawn was not observed. Precipitates of the test substance in the agar were found starting at 500 or 1000 µg/plate in all strains without or with S9 mix, respectively.

Applicant's summary and conclusion

Executive summary:

The mutagenic potential of the test substance was evaluated in a Salmonella/microsome test with the S. typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and TA 1538 in the presence and absence of S9 mix according to OECD TG 471. Evidence of mutagenic activity was not seen up to the maximum soluble dose level of 2500 µg/plate. No substantial increases in revertant colony numbers of any of the five tester strains were observed at any dose level in the presence and absence of metabolic activation. Therefore, the test substance was considered to be non-mutagenic in the Salmonella typhimurium reverse mutation assay.