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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2 September 1994 to 17 October 1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study according to international guideline

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
The assay is based on the use of 5 Salmonella typhimurium tester strains that revert from histidine dependence (auxotrophy) to histidine independence (prototrophy) in the presence of a genotoxic agent, with or without metabolic activation system.
This study was carried out with the preincubation method.
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: solution
Details on test material:
Test compound/batch: SR 48941/ batch 4 SNP 006.
SR 48941 was extemporaneously dissolved and diluted in dimethyl sulfoxide (Merck, 99.8 % purity) in order to obtain the following concentrations: 1, 5, 10, 25, 50, 100, 250, 500, 1000 and 2500 µg/plate.

Method

Target gene:
Histidine
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102
Additional strain / cell type characteristics:
other: TA1535 and TA 1537: rfa uvrB; TA 98 and TA100: rfa uvrB with R factor plasmid pKM 101, TA102: rfa with the R factor plasmid pKM101 and pAQ1.
Metabolic activation:
with and without
Metabolic activation system:
S-9 mix (2.5%) from Aroclor 1254-induced rat liver
Test concentrations with justification for top dose:
Preliminary study (TA100)
Preincubation method: 0, 10, 50, 100, 250, 500, 1000 and 2500 µg/plate on TA100

Main study(TA98, TA100, TA102, TA1535, TA1537)
Plate incorporation method: 0, 10, 50, 100, 250, 500 and 1000 µg/plate

Additional assay on TA1537: 0, 1, 5, 10, 50, 100 and 250 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
Dimethyl sulfoxide
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
mitomycin C
other: 2-aminoanthracene, Danthron
Remarks:
Further information on positive controls under section 'Any other information on materials and methods incl. tables".
Details on test system and experimental conditions:
Main study method: preincubation
Numbers od replications: 3
Exposure duration: 48 hours for TA98, TA100, TA1535, TA1537; 72 hours for TA102
The bacterial suspension used for each test was obtained from a bacterial inoculum grown in nutrient broth in a shaking incubator for approximately 7 hours at 37°C. The bacterial density ranged from 1 to 2 x 10^9 bacteria/ml.
Evaluation criteria:
Criteria for bacterial toxicity are:
- reduced number of revertant colonies/plate,
- sparsity of the bacterial background lawn when compared with control plates

The compound is considered genotoxic:
- if the increase in the number of revertants is concentration-related, or
- if, at one concentration tested (at least), the induction factor is equal to or higher than 2 with TA98, TA100 and TA102 and higher than 3 with TA1535 and TA1537 and,
- if the positive response is reproducible in an independent assay.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 102
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
From 250 µg/plate upwards
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
positive
Remarks:
A significant increase in the number of His+ revertant colonies/plate was seen.
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
From 250 µg/plate upwards with S-9 mix and from 500 µg/plate upwards without S9- mix
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
positive
Remarks:
A significant increase in the number of His+ revertant colonies/plate was seen.
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
From 500 µg/plate upwards
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
at 1000 µg/plate with S-9 mix
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
positive
Remarks:
A significant increase in the number of His+ revertant colonies/plate was seen.
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive

In conclusion, SR 48941 was genotoxic in the Ames test, with or without metabolic activation.