1-benzo-2-oxa-1,3-diazole oxide

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

other information

Study period:

1980

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Data source

Reference

Reference Type:

publication

Title:

THE MUTAGENIC ACTION OF QUINDOXIN, CARBADOX, OLAQUINDOX AND SOME OTHER N-OXIDES ON BACTERIA AND YEAST

Author:

VOOGD CE, VAN DER STEL JJ, JACOBS JA

Year:

1980

Bibliographic source:

MUTAT RES 78:233-242,1980

Materials and methods

Principles of method if other than guideline:

The plate incorporation method and the fluctuation method were used to test the bacterial reverse mutation. In the plate incorporation method only two strains of bacteria instead of five strains were used. No strain with AT base pair at the primary reversion site was used. Bacteria were not exposed to the test substance in the presence of a metabolic activation system. The use of concurrent strain-specific positive and negative controls was not documented.
Fluctuation tests were carried using a Klebsiella pneumoniae mutant, requiring uracil and proline as growth factors, and Escherichia coli K12 Hfr Hayes.

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

1-benzo-2-oxa-1,3-diazole oxide

EC Number:

207-559-1

EC Name:

1-benzo-2-oxa-1,3-diazole oxide

Cas Number:

480-96-6

Molecular formula:

C6H4N2O2

IUPAC Name:

2,1,3-benzoxadiazol-1-ium-1-olate

Specific details on test material used for the study:

SOURCE: Bayer GmbH, Leverkusen (F.R.G.)

Method

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Species / strain 2

Species / strain / cell type:

bacteria, other: Klebsiella pneumoniae

Additional strain / cell type characteristics:

other: requiring uracil and proline as growth factors

Metabolic activation:

without

Test concentrations with justification for top dose:

plate incorporation method: Benzofuroxan concentration 1/0.5/0.2/0.1/0.05/0.02/0.01/0.005 mmole/L
fluctuation method: Benzofuroxan concentration in top agar 2/1/0.5/0.2/0.1 mmole/L

Vehicle / solvent:

Benzofuroxan was dissolved in dimethylsulphoxide.

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

no

Remarks:

The use of concurrent strain-specific positive and negative controls was not documented.

Details on test system and experimental conditions:

PLATE-INCORPORATION TEST
The plate-incorporation test developed by Ames (Ames et al., 1975) was used with Salmonella typhimurium TA98 and TA100. These strains were kindly supplied by Professor Ames (Department of Biochemistry, University of California, Berkeley, CA 94720 BC 01, U.S.A.). No metabolic activation was applied. On each plate 3 ml of top agar, in which the compound under investigation was present, were added to 20 ml of the selection medium. The compounds were dissolved in dimethylsulphoxide.

FLUCTUATION TEST
Fluctuation tests (Luria and Delbrtick, 1943) were carried out as described in Voogd et al., 1977. As test organisms a Klebsiella pneumoniae mutant, requiring uracil and proline as growth factors, and Escherichia coli K12 Hfr Hayes were used. After incubation during 20 h at 37°C, the total number of streptomycin-resistant (including streptomycin-dependent) bacteria was determined by the pour-plate technique. The average spontaneous mutation rate of Klebsiella pneumoniae was 0.1676 × 10 -9 (S.D. 0.0304 × 10 -9) obtained from 26 independent experiments, and that of E. coli was 0.2393 × 10 -9 (S.D. 0.0596 × 10 -9) obtained from 23 experiments.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 100

Metabolic activation:

without

Genotoxicity:

positive

Vehicle controls validity:

not valid

Untreated negative controls validity:

not valid

Positive controls validity:

not valid

Test results 2

Species / strain:

S. typhimurium TA 98

Metabolic activation:

without

Genotoxicity:

positive

Vehicle controls validity:

not valid

Untreated negative controls validity:

not valid

Positive controls validity:

not valid

Test results 3

Species / strain:

other: Klebsiella pneumonia

Genotoxicity:

positive

Additional information on results:

PLATE-INCORPORATION TEST
A weak mutagenic activity was observed with Salmonella typhimurium TA100 when benzofuroxan was present in the top agar at 1 mmole/L and with Salmonella typhimurium TA98 when benzofuroxan was present in the top agar at 0.5 mmole/L.

FLUCTUATION TEST
An increase in the mutation rate of Klebsiella pneumoniae was caused by benzofuroxan. In this test, benzofuroxan doubled the mutation rate at a concentration of 0.01 mmole/L.

Applicant's summary and conclusion

Conclusions:

Benzofuroxan may cause both base-pair substitutions and frame-shift mutations. However, this study is not reliable due to major methodological deficiencies. Therefore, the data are insufficient for assessment.

Executive summary:

The plate incorporation method and the fluctuation method were used to test the bacterial reverse mutation. In the plate incorporation method Salmonella typhimurium TA98 and TA100 were used. No strain with AT base pair at the primary reversion site was used. Bacteria  were not  exposed  to  the  test  substance  in  the  presence  of  a metabolic   activation   system. The use of concurrent strain-specific positive and negative controls was not documented.

Fluctuation tests were carried using a Klebsiella pneumoniae mutant, requiring uracil and proline as growth factors, and Escherichia coli K12 Hfr Hayes.

A weak mutagenic activity was observed with Salmonella typhimurium TA100 when benzofuroxan was present in the top agar at 1 mmole/L and with Salmonella typhimurium TA98 when benzofuroxan was present in the top agar at 0.5 mmole/L. An increase in the mutation rate of Klebsiella pneumoniae was caused by benzofuroxan. In this test, benzofuroxan doubled the mutation rate at a concentration of  0.01 mmole/L.

Benzofuroxan may cause both base-pair substitutions and frame-shift mutations. However, this study is not reliable due to major methodological deficiencies. Therefore, the data are insufficient for assessment.