2-Thiopheneacetic acid, .alpha.-hydroxy-.alpha.-2-thienyl-, methyl ester

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:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Techniques
The Ames II test was conducted with and without addition of microsomal liver enzymes from rats (Aroclor 1254-induced). Following base-pair and
frameshift-specific tester strains were used: S. typhimurium TA Mix (TA 7001, TA 7002, TA 7003, TA 7004, TA 7005 and TA 7006) and TA 98,
respectively. The Salmonella strains and method are described by Gee et al. (1998).
The assay was performed according to the instruction manual for the Ames II (Xenometrix, BoulderIUSA). 0.01 ml ofthe vehicle, test article or
positive control were incubated with 0.24 ml bacterial overnight culture (ca 10E+7/ml)/exposure medium in 24-well plates for 90 min at 37°C,
250 rpm. With metabolic activation 0.2 ml strain mixture and 0.04 ml S9-mix (30%) were used. After 90 min the exposed cultures were diluted with
pH indicator medium lacking histidine and aliquoted into 48 wells of a 384-well plate (3 replicates) using a 8-channel pipettor. The plates were
incubated for 48 hrs at 37°C. To confirm the sensitivity of the tester strains and the metabolic capacity of the S9 fractions known diagnostic
mutagens were used (2-nitrofluorene/2-NF, 4-nitroquinoline-N-oxide/4-NQO and 2-aminoanthracene/2-AA, respectively).
Evaluation
The purple pH indicator bromocresol turns yellow as the pH drops due to the accumulation of catabolites from the metabolic activity of revertant
cells.The number of positive wells (yellow) out of a total of 48 wells is indicative of the reversion frequency per replicate/concentration and was
compared to the number of spontaneous revertant wells of the solvent control. Each test point contains 48 wells of a 384-well plate. In each 48-well
section, the wells were scored for the number of revertant wells (yellow) and the mean value of the triplicates was calculated.
Assessment and Acceptance Criteria
The experiment is regarded valid, if the vehicle control shows the normal spontaneous revertant frequency and the diagnostic mutagens cause the
expected increase in the mutation rate. The test chemical was classified according to the following criteria:
Negative: <=8/48 well Equivocal: 9-12/48 wells Positive: >=13/48 wells
The historical control range experienced in this laboratory covering more than 100 experiments is 0-7/48 wells.
A concentration-dependent increase of revertant wells (mean of triplicate) over the vehicle control range is indicative for a genotoxic activity of the
test article.
Because the results were unequivocal, no detailed statistical evaluation or repeat experiment were performed.

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Di-2-thienylglycolic acid methyl ester

Cas Number:

26447-85-8

Molecular formula:

C11 H10 O3 S2

IUPAC Name:

Di-2-thienylglycolic acid methyl ester

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not determined

Test results 2

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 determined

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:

Based on the described results it is concluded, that BA 679 Thienyl-glycolester, when tested up to toxic and insoluble concentrations, caused
neither base-pair substitution nor frameshift mutations in bacteria. No evidence of genotoxic activity was observed in a series of S. typhimurium
tester strains in the Ames II (TA Mix and TA 98) in the absence and presence of metabolic activation. The test compound is, therefore, classified
as "Ames II negative".