sodium 2,4-dihydroxy-3,3-dimethylbutanoate

Genetic toxicity: in vitro

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:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

The Ames II Assay is a liquid version of the classical Ames test. It is performed in microwell plates using a modified fluctuation test protocil. Beside the traditional tester strain TA 98, a set of 6 his- mutant strains TA 7001- TA 7006 (Ames II tester strains was developed) The principle of the assa is that mutations are detected by the reversion of mutations present in the amino acid requiring bacterial strains. This leads to a restoration of the functional capability of the bacteria to synthesize the essential amino acid and thus the ability to grow in the absence of the amino acid required by the parent strains. In the Ames II assay this growth leads to an accumulation of catabolites from the metabolic activity of revertants dropping down the pH and, thus, turning the purple Ames II reversion indicator medium yellow.

GLP compliance:

no

Remarks:

but partially compliant

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

sodium (2R)-2,4-dihydroxy-3,3-dimethyl-butanoate

Cas Number:

60979-68-2

Molecular formula:

C6 H11 Na O4

IUPAC Name:

sodium (2R)-2,4-dihydroxy-3,3-dimethyl-butanoate

Details on test material:

- Name of test material (as cited in study report): Natriumpantoat roh, ber. 100%
- Physical state: yellowish liquid
- Composition of test material, percentage of components: 20% main component, 65% water, 14% NaCl
- Lot/batch No.: B 671 Mischprobe
- Storage condition of test material: room temperature

Method

Target gene:

His

Species / strain

Species / strain / cell type:

S. typhimurium, other: TA 98, TA 7001, TA 7002, TA 7003, TA 7004, TA 7005, TA 7006

Details on mammalian cell type (if applicable):

- Type and identity of media: Ames II exposure medium and Ames II reversion indicator medium
- Properly maintained: yes
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

S9

Test concentrations with justification for top dose:

0, 8, 40, 200, 1000, 5000, 10000 µg/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: water
- Justification for choice of solvent/vehicle: good solubility of the test material

Controls

Controls 1

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

yes

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

- S9

Controls 2

Positive control substance:

4-nitroquinoline-N-oxide

Remarks:

- S9

Controls 3

Positive control substance:

other: 2-amino anthracene

Remarks:

+ S9

Details on test system and experimental conditions:

METHOD OF APPLICATION: in suspension

DURATION
- Exposure duration: 90 minutes
- Expression time (cells in growth medium):
- Selection time (if incubation with a selection agent): 48 hours

SELECTION AGENT (mutation assays): histidine

NUMBER OF REPLICATIONS: 3

DETERMINATION OF CYTOTOXICITY
relative total growth and clearing or diminution of the backround lawn leading from trubid to non-turbid purple wells.

OTHER:

Evaluation criteria:

The test chemical is considered positive in this assay if the following criteria are met :
• A dose-related increase in the number of positive wells by a factor of about 2 (calculated primarily on the basis of baseline data) in at least one tester strain either without S-9 mix or after adding a metabolizing system .
A test substance is generally considered non-mutagenic in this test if :
• The number of revertant wells for all tester strains were within the historical negative control range under all experimental conditions .

Results and discussion

Test results

Species / strain:

S. typhimurium, other: TA 98, TA 7001, TA 7002, TA 7003, TA 7004, TA 7005, TA 7006

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

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:

According to the results of the present study, the test substance did not lead to an increase in the number of revertant wells either without S-9 mix or after adding a metabolizing system.