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
Study period:
2009
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test substance: Diethylphosphonoacetic acid (impurity of BIBW 2992)
Batch no.: 1041020
Appearance: white, crystalline substance
Purity: 99.6 %
Certificate of analysis: 11 March 2009
To be retested: February 2010
Storage conditions: At room temperature in the dark (ambient humidity)
Manufacturer: Boehringer Ingelheim Pharma GmbH & Co. KG,
88397 Biberach (Germany)

Method

Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
S9 mix: Aroclor 1254-unduced rat liver microsomal fraction and cofactors
Test concentrations with justification for top dose:
100-5000 ug/plate

A maximum concentration of 5000 μg/plate should be investigated according to relevant
guidelines. Diethylphosphonoacetic acid did not precipitate up to the highest concentrations
of 5000 μg/plate in a non-GLP solubility test. Therefore, 5000 μg/plate was investigated as
the highest concentration.
Vehicle / solvent:
DMSO was used as solvent vehicle and negative control.
Controls
Untreated negative controls:
yes
Remarks:
DMSO only
Negative solvent / vehicle controls:
yes
Remarks:
DMSO only
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
mitomycin C
other: 2.Aminoanthracene
Remarks:
2-Nitrofluorene, Sodium azide, Mitomycin C and 9-Aminoacridine without activation; 2-Aminoanthracene with activation
Details on test system and experimental conditions:
Revertant his+ colonies were counted using the automatic colony counter IPI Analyzer 982 B
after incubation at 37°C for 2 days (TA 102: 3 days) and the data were collected by computer.
For all replicate platings, the mean number of revertants per test concentration was
calculated. The condition of the background bacterial lawn (residual growth on minimum
histidine) was evaluated macroscopically for evidence of bacteriotoxicity induced by the test
substance. If extreme thinning or complete lack of the microcolony lawn compared to the
negative, vehicle control plates was observed, no revertants were counted. Evidence of test
substance precipitates in the agar overlay was recorded.
Evaluation criteria:
A reproducible, concentration-dependent increase in the number of revertants of at least one
tester strain over the vehicle control value and/or outside the historical control range is
indicative of genotoxic activity.

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Additional information on results:
Diethylphosphonoacetic acid did not increase the number of revertant colonies in different
tester strains of S. typhimurium compared to the negative control when tested up to
bacteriotoxic concentrations. Furthermore, metabolic activation by S9 mix did not alter the
mutation frequency of these bacterial strains. All values were clearly within the historical
background data range.
The validity of this study is given since the vehicle control plates showed spontaneous
revertants in different tester strains of S. typhimurium at frequencies similar to those
described in the literature and within the historical control range experienced in our
laboratory.
The diagnostic mutagens NaN3, 9-AA, 2-NF, MMC and 2-AA showed the expected strain
specific responses in the absence and presence of mammalian liver enzymes, respectively,
demonstrating the validity of this study.
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):
negative

Diethylphosphonoacetic acid caused neither base-pair substitutions nor frameshift mutations
in different strains of S. typhimurium in the presence and absence of metabolic activation
when tested up to bacteriotoxic concentrations. Based on these results it was concluded, that
the test substance is "Ames negative".
Executive summary:

SUMMARY

Diethylphosphonoacetic acid, a possible impurity in BIBW 2992, triggered a structural alert for mutagenicity in the DEREK in silico system. Therefore, Diethylphosphonoacetic acid was investigated under GLP conditions to see whether it induces mutations in the Salmonella typhimurium strains TA 1535, TA 100, TA 102 (sensitive to base-pair substitution), TA 1537 and TA 98 (sensitive to frameshift mutagens) both in presence and absence of a metabolic activation system (S9 mix: Aroclor 1254-induced rat liver microsomal fraction and cofactors). Diethylphosphonoacetic acid was dissolved in dimethylsulfoxide (DMSO) and added to bacterial cultures in triplicates to give the final concentrations of 100 to 5000 μg/plate in the plate test. No repeat experiment was performed due to a clear negative result.

Solubility and Toxicity

Diethylphosphonoacetic acid did not precipitate up to the highest concentration of 5000 μg/plate. A strain-dependent bacteriotoxicity was observed primarily at concentrations ≥1000 μg/plate.

Mutagenicity

Diethylphosphonoacetic acid did not increase the number of revertant colonies in different tester strains of S. typhimurium compared to the negative control when tested up to bacteriotoxic concentrations. Furthermore, metabolic activation by S9 mix did not alter the mutation frequency of these bacterial strains. All values were clearly within the historical background data range. The validity of this study is given since the vehicle control plates showed spontaneous revertants in different tester strains of S. typhimurium at frequencies similar to those described in the literature and within the historical control range experienced in our laboratory. The diagnostic mutagens NaN3, 9-AA, 2-NF, MMC and 2-AA showed the expected strain specific responses with and without metabolic activation.

Conclusion

Diethylphosphonoacetic acid caused neither base-pair substitutions nor frameshift mutations in different strains of S. typhimurium in the presence and absence of metabolic activation when tested up to bacteriotoxic concentrations. Based on these results it was concluded, that the test substance is "Ames negativ