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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 2008
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:
2008
Report date:
2008

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
Micromethod Ames's test
GLP compliance:
no
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Reference substance name:
Avena Sativa leaf/stem extract
EC Number:
948-064-7
IUPAC Name:
Avena Sativa leaf/stem extract
Test material form:
solid: particulate/powder
Specific details on test material used for the study:
The test substance is a dry extract containing maltodextrine. This compound is not expected to interfere with the results of the test as it is an inert substance.

Method

Target gene:
His locus
Species / strain
Species / strain / cell type:
other: Salmonella typhimurium TA1537, TA98, TA100
Details on mammalian cell type (if applicable):
rfa mutation for all strains; pKM 101 ampicillin resistance plasmid for strains TA100 and TA 98
Additional strain / cell type characteristics:
DNA polymerase A deficient
Metabolic activation:
with and without
Metabolic activation system:
S9 fraction of rat liver
Test concentrations with justification for top dose:
0.29, 0.86, 2.57, 7.72, 23.15, 69.44, 208.33, 625, 1250, 2500 µg/plate
Solubility was the limiting factor for maximum dose.
Vehicle / solvent:
DMSO
Controls
Negative solvent / vehicle controls:
yes
True negative controls:
yes
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
other: 2-anthramine
Details on test system and experimental conditions:
Incubation during 48h.
Each dose is performed in triplicate, per strain and type of treatment.
Rationale for test conditions:
Reference to the guideline study
Evaluation criteria:
Mean number of spontaneous revertants per plate
Statistics:
Yes, method not specified

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with
Genotoxicity:
positive
Remarks:
significant increase of revertants at 69.04 µg/plate but induction ratio of 3 was not reached
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
without
Genotoxicity:
ambiguous
Remarks:
increase in revertants at 625 to 2500 µg/plate but induction ratio of 2 not reached
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with
Genotoxicity:
positive
Remarks:
significant increase in revertants at 2500 µg/plate but induction ratio of 2 not reached
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Validity criteria were fulfilled.
Results on TA100, without metabolic activation at the three highest doses: statistically significant increase in the mean number of revertants in presence of test item. But induction ratio of 2 was not reached and the mean number of revertants were within the limits of historical data for negative control in the same experimental conditions. However, taking into account the absence of toxicity of test item at the doses tested, the clear dose-response relationship obseved and the fact that the maximum tested dose was limited by the solubility of test item, results were considered equivocal. To confirm or invalidate the mutagenicity of test item in this strain, an additional assay under the same experimental conditions but using a narrower range of doses (e.g. 3000-2500-2000-1500-1000-750-500-250) should be undertaken.
Remarks on result:
other: no biologically significant
Remarks:
No dose-response relationship

Applicant's summary and conclusion

Conclusions:
The test item S02542 provided by Institut de Recherche Pierre Fabre induced an equivocal result on Salmonella typhimurium strain TA100, in absence of metabolic activation, in a screening micromethod assay of the Ames's test without repetition.
In return, no mutagenic activity was observed in the Salmonella typhimurium strains TA1537 and TA98 in absence or in presence of metabolic activation system, or in strain TA100 in presence of metabolic activation.
An additional assay should be performed, under the same experimental conditions, in strain TA100 in absence of metabolic activation, using a narrower dose range between 3000 and 250 µg/mL.