TOMILAC 214

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: genome mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Between 23 January and 13 February 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Recently conducted GLP compliant study using the most recent test methods

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Details on test material:

- Name of test material (as cited in study report): JKY-214
- Physical state: white solid
- Analytical purity: No information
- Lot/batch No.: Y002E
- Expiration date of the lot/batch: No information
- Stability under test conditions: No information. Assumed stable due to no data to the contrary
- Storage condition of test material: room temperature in the dark
- Other:

Method

Target gene:

Mutagenic activity assessed by exposing histidine auxotrophs of Salmonella typhimurium and tryptophan auxotrophs of Escherichia coli

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Details on mammalian cell type (if applicable):

not applicable

Additional strain / cell type characteristics:

not applicable

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Details on mammalian cell type (if applicable):

not applicable

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

phenobarbitone/beta­naphthoflavone

Test concentrations with justification for top dose:

0, 0.15, 0.5, 1.5, 5, 15, 50, 150, 500, 1500 and 5000 µg/plate for preliminary toxicity test

The concentrations tested were 0, 50, 150, 500, 1500 and 5000 µg/plate for the definitive test.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: dimethyl formamide
- Justification for choice of solvent/vehicle: Test sample was fully soluble in this solvent, which is considered suitable for the test system. Substance was insoluble in other solvents tested.

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Dimethyl formamide

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: see below for details

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium; in agar (plate incorporation)

Evaluation criteria:

There are several criteria for determining a positive result, such as a dose-related increase in revertant frequency over the dose range tested and/or a reproducible increase at one or more concentrations in at least one bacterial strain with or without metabolic activation. Biological relevance of the results will be considered first, statistical methods, as recommended by the UKEMS (5) can also be used as an aid to evaluation, however, statistical significance will not be the only determining factor for a positive response.
A test material will be considered non-mutagenic (negative) in the test system if the above criteria are not met.
Although most experiments will give clear positive or negative results, in some instances the data generated will prohibit a definitive judgement about the test material activity. Results of this type will be reported as equivocal.

Statistics:

Kirkland D J (Ed) (1989) Statistical Evaluation of Mutagenicity Test Data. UKEMS Sub-committee on Guidelines for Mutagenicity Testing, Report - Part III, Cambridge University Press.

Results and discussion

Test results

Test results 1

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:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 2

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: none reported
- Effects of osmolality: none reported
- Evaporation from medium: none reported
- Water solubility: not applicable
- Precipitation: some precipitation but did not prevent viewing plates
- Other confounding effects: non reported

RANGE-FINDING/SCREENING STUDIES:
The concentrations tested were 0, 0.15, 0.5, 1.5, 5, 15, 50, 150, 500, 1500 and 5000 µg/plate for preliminary toxicity test and 0, 50, 150, 500, 1500 and 5000 µg/plate for the definitive test producing no significant increases in revertent colonies.

COMPARISON WITH HISTORICAL CONTROL DATA:
All data was in the expected range based upon historical data

ADDITIONAL INFORMATION ON CYTOTOXICITY:
no reduction in the background lawn. A cloudy film and precipitate were observed but these did not prevent accurate scoring of revertent colonies.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

           

 

 

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with and without metabolism

The substance is non mutagenic under the conitions of the test.

Executive summary:

The Ames test was conducted using four strains of salmonella and one strain of E-coli using the plate incorporation method. The test substance was prepared at five dose levels for the main test upto a maximum concentration of 5000 µg/plate in dimethyl formamide.

The substance caused no reduction in the background lawn indicating the substance was not toxic under the conitions of the test. Furthermore, a slight film and precipitation was not sufficient to prevent accurate scoring to indicate that the substance caused no significant increases in the frequency of revertent colonies indicating that the substance is non mutagenic. Concurrent solvent and positive controls gave results gave expected results and demonstrated that the test system was adequate to assess the substance.