Registration Dossier

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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: well performed GLP and OECD guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report date:
1998

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
N-[4-(aminocarbonyl)phenyl]-4-methoxy-3-nitrobenzamide
EC Number:
298-790-7
EC Name:
N-[4-(aminocarbonyl)phenyl]-4-methoxy-3-nitrobenzamide
Cas Number:
93839-20-4
Molecular formula:
C15H13N3O5
IUPAC Name:
N-(4-carbamoylphenyl)-4-methoxy-3-nitrobenzamide

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254 induced rat liver S9-mix
Test concentrations with justification for top dose:
First plate incorporation test: 0, 50, 160, 500, 1600 and 5000 µg/plate
Second plate incorporation test: 0, 5, 10, 25, 50, 100 and 160µg/plate
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
other: N-Methyl-N-nitro-N-nitrosoguanidine, 2-aminoanthracene
Evaluation criteria:
The assay is considered valid if the following criteria are met:
- the solvent control data are within the laboratory's normal control range for the spontaneous mutant frequency
- the positive controls induced increases in the mutation frequency which were both statistically significant and within the laboratory's normal range

A test compound is classified as mutagenic if it has either of the following effects:
a) it produces at least a 2-fold increase in the mean number of revertants per plate of at least one of the tester strains over the mean number of revertants per plate of the appropriate vehicle control at complete bacterial background lawn
b) it induces a dose-related increase in the mean number of revertants per plate of at least one of the tester strains over the mean number of revertants per plate of the appropriate vehicle control in at least two to three concentrations of the test compound at complete bacterial background lawn.

If the test substance does not achieve either of the above criteria, it is considered to show no evidence of mutagenic activity in this system

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Metabolic activation:
with and without
Genotoxicity:
positive
Remarks:
TA 98, TA 1537, TA 100 with and without S9-mix, TA 1535 and WP2 uvrA with S9-mix
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive

The results lead to the conclusion that the tested substance is mutagenic in these bacterial test systems with and without an exogenous metabolizing system.
Executive summary:

The substance was tested for mutagenicity with the strains TA 100, TA 1535, TA 1537 and TA 98 of Salmonella typhimurium and Escherichia coli WP2uvrA. Two independent mutagenicity studies were conducted (two plate incorporation tests), each in the absence and in the presence of a metabolizing system derived from a rat liver homogenate. The second plate incorporation test was performed only with the strains TA 100 and TA 1537 in the absence and in the presence of S9-mix. For both studies, the compound was dissolved in DMSO, and each bacterial strain was exposed to 5 dose levels, respectively 6 dose levels in the second plate incorporation test. The contentrations for the first plate incorporation test were 50, 160, 500, 1600 and 5000 µg/plate. Because of toxicity and mutagenicity in the first plate incorporation test dose levels from 5 to 160 µg/plate were chosen for the second plate incorporation test. Control plates without mutagen showed that the number of spontaneous revertant colonies was within the laboratory's historical control range. All the positive control compounds showed the expected increase in the number of revertant colonies.

Toxicity: In the first plate incorporation test toxicity was observed with and without metabolic activation at a concentration of 160 µg/plate and above. Additionally, in the absence of metabolic activation the test compound proved to be toxic to the bacterial strain TA 1537 at the concentration of 50 µg/plate. In the second plate incorporation test toxicity was observed with and without metabolic activation in a dose range of 50 to 100 µg/plate and above.

Mutagenicity: In the absence and in the presence of the metabolic activation system the test compound induced a significant and dose-dependent increase in the number of revertant colonies with the bacterial strain TA 100. At toxic doses increased numbers of revertants were obtained with S9-mix in the strains TA 1535 and WP2 uvrA, and with and without S9-mix in the tester strains TA 1537 and TA 98.