Pregn-4-ene-3,20-dione, 21-(acetyloxy)-16-methyl-, (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:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

other information

Study period:

Dec 1995 to Feb 1996

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:

1996

Report date:

1996

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

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

39987-86-5

EC Number:

609-766-6

Cas Number:

39987-86-5

IUPAC Name:

39987-86-5

Constituent 2

Reference substance name:

21-Hydroxy-16 alpha-methyl-4-pregnene-3,20-dione

IUPAC Name:

21-Hydroxy-16 alpha-methyl-4-pregnene-3,20-dione

Constituent 3

Reference substance name:

M-DOC

IUPAC Name:

M-DOC

Details on test material:

- Name of test material (as cited in study report): ZK 9340
- Batch No.: 34514021
- Stability under test conditions: The solution and further dilutions were prepared immediately before addition to the test bacteria.

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:

100, 250, 500, 1000, 2500, 5000 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:

cytotoxicity

Remarks:

in all strains at 5000 µg/plate (-/+ S9 mix)

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 9340 at any of the 6 concentrations tested between 100 and 5000 µg/plate, either in the absence or precence of S9 mix.

Growth inhibition of the background lawn was observed in all strains tested at 5000 µg/plate with and without S9 mix. Visible precipitates in the agar were found on all strains from 2500 µg/plate onwards.

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 recommended dose level of 5000 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.