Pregna-4,6-diene-3,20-dione, 17-(acetyloxy)-6-chloro-1-(chloromethyl)-, (1.alpha.)-

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:

February to March 1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1983

Deviations:

yes

Remarks:

no bacteria strain included to detect cross-linking mutagens (e.g. TA 102)

Principles of method if other than guideline:

Direct plate incorporation procedure was performed. No E. coli WP2 or S. typhimurium TA102 strain tested; no preincubation test performed. These requirements were first formulated in the adoption of the guideline in 1997 and thus the study was conducted prior to implementation of these requirements.

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

(1R,3aS,3bR,9S,9aS,9bS,11aS)-1-acetyl-5-chloro-9-(chloromethyl)-9a,11a-dimethyl-7-oxo-1H,2H,3H,3aH,3bH,7H,8H,9H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-1-yl acetate

EC Number:

605-617-4

Cas Number:

17183-98-1

Molecular formula:

C24 H30 Cl2 O4

IUPAC Name:

(1R,3aS,3bR,9S,9aS,9bS,11aS)-1-acetyl-5-chloro-9-(chloromethyl)-9a,11a-dimethyl-7-oxo-1H,2H,3H,3aH,3bH,7H,8H,9H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-1-yl acetate

Method

Target gene:

Histidine gene locus

Species / strain

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

liver S9-mix from Aroclor 1254 -treated rats

Test concentrations with justification for top dose:

6-Chlor-Chlormethyldien: six concentrations from 0.005 to 0.5 mg/plate
9-Acridinamine, hydrochloride: 100 µg/plate
2-Aminoanthracene: 2.0 µg/plate
2-Nitrofluorene: 10 µg/plate
Benzo[a]pyrene: 5 µg and 10.0 µg/plate
Sodium azide: 5 µg/plate
Cyclophosphamide: 400 µg/plate

Controls

Negative solvent / vehicle controls:

yes

Remarks:

DMSO and phosphate buffer pH 7.4, 0.1 mol/l

Positive controls:

yes

Positive control substance:

other: 9-Acridinamine, hydrochloride; 2-Aminoanthracene; 2-Nitrofluorene; Benzo[a]pyrene; Sodium azide; Cyclophosphamide

Details on test system and experimental conditions:

NUMBER OF REPLICATIONS:
- Number of cultures per concentration: triplicate
- Number of independent experiments: one

METHOD OF TREATMENT/ EXPOSURE:
- Test substance added in agar (plate incorporation)

METHODS FOR MEASUREMENT OF CYTOTOXICITY
- Method: background growth inhibition

Evaluation criteria:

The plates were scored for the number of mutant colonies with an automated colony counter (Artek M 982B, Artek Systems Corporation, Farmingdale, NY, USA). The arithmetic means of the number of mutant colonies of the 3 parallel plates in the negative control groups were compared with those of the compound groups. A positive response was considered if at least 5 mg/plate or up to a toxic dose had been tested (or the compound formed precipitates in the agar) and if the number of induced revertants compared to the number of spontaneous ones was reproducibly higher than 2-fold. A dose-dependent increase in the number of revertants was also considered to indicate a mutagenic effect.

Results and discussion

Test results

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

There were visible precipitates in the agar starting from 0.05 mg/plate in all tested strains in absence and presence of S9 mix.

Applicant's summary and conclusion

Conclusions:

No increase of reverse gene mutations in bacteria induced by the test item up to maximum concentration of 0.5 mg/ plate (precipitation started at 0.05 mg/ plate).

Executive summary:

6 -Chlor-Chlormethyldien (ZK 10882) was examined for mutagenic activity up to 500 µg/plate in the five histidine-dependent Salmonella typhimurium strains TA 1535, TA 100, TA 1537, TA 1538 and TA 98 with and without metabolic activation.

No cytotoxic effect was observed up to 0.5 mg/plate with and without S9 mix. There were visible precipitates in the agar from 0.05 mg/plate onwards with and without S9 mix in all tested strains.

There was no evidence for a mutagenic activity of 6 -Chlor-Chlormethyldien, when tested up to the precipitating dose level of 0.5 mg/plate in the absence and presence of S9 mix.