(Benzyloxycarbonyl)methyl 4-(1-Butyl-5-cyano-1,6-dihydro-2-hydroxy-4-methyl-6-oxo-3-pyridylazo)-benzoate

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From May 15th to July 31st, 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosomal Aberration Test)

Version / remarks:

Adopted July 21st, 1997

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

Yellow 6314-PPT

IUPAC Name:

Yellow 6314-PPT

Test material form:

solid

Specific details on test material used for the study:

On the day of the experiment (immediately before treatment), the test item was dissolved in DMSO. The fìnal concentration of DMSO in the culture medium was 0.5 % (vlv).

Method

Species / strain

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Metabolic activation system:

S9 liver fractions of rats, induced with phenobarbital/beta-naphthoflavone

Test concentrations with justification for top dose:

Concentration in the main test I (with metabolic activation): 6.3, 12.5, 25.0, 50.0, 75.0, 100.0 μg/ml – Precipitation interval: 18h, exposure: 4h.
Concentration in the main test II (with metabolic activation): 6.3, 12.5, 25.0, 50.0, 75.0, 100.0 μg/ml – Precipitation interval: 28h, exposure: 4h.

Concentration in the main test I (without metabolic activation): 1.3, 2.5, 5.0, 10.0, 20.0, 30.0 μg/ml – Precipitation interval: 18h, exposure: 4h.
Concentration in the main test II (without metabolic activation): 0.3, 0.6, 1.3, 2.5, 5.0, 10.0 μg/ml – Precipitation interval: 18h, exposure: 18h.
Concentration in the main test II (without metabolic activation): 1.3, 2.5, 5.0, 10.0 μg/ml – Precipitation interval: 28h, exposure: 28h.

Vehicle / solvent:

DMSO

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

ethylmethanesulphonate

Details on test system and experimental conditions:

The test item, dissolved in DMSO, was assessed for its potential to induce structural chromosome aberrations in V79 cells of the Chinese hamster in vitro in two independent experiments. Following study design was performed:
- without metabolic activation:
experiment I with exposure period 4h, recovery 14h and preparation interval 18h.
experiment II with exposure period 18h and preparation interval 18h.
experiment II with exposure period 28h and preparation interval 28h.
- with metabolic activation:
experiment I with exposure period 4h, recovery 14h and preparation interval 18h.
experiment II with exposure period 4h, recovery 24h and preparation interval 28h.
ln each experimental group two parallel cultures were set up. Per culture 100 metaphase plates were scored for structural chromosome aberrations. The highest applied concentration in the pre-test on toxícity (250 μg/ml) was chosen with regard to the solubility properties of the test item in DMSO. Dose selection of the cytogenetic experiments was performed considering the toxicity data and the occurrence of precipitation.

Results and discussion

Test results

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

Toxic effects indicated by reduced cell numbers of about and below 50 % of control were observed in experiment I and ll at preparation interval 18 hrs in the absence of S9 mix and in experiment ll at preparation interval 28 hrs in the presence of S9 mix.
Besides in experiment I after 4 hrs treatment in the presence of S9 mix and in experiment ll after 28 hrs continuous treatment in the absence of S9 mix, concentrations showing clearly reduced cell numbers were not evaluable for cytogenetic damage.
ln both independent experiments, neither a statistically significant nor a biologically relevant increase in the number of cells carrying structural chromosomal aberrations was observed after treatment with the test item. No relevant increase in the frequencies of polyploid metaphases was found after treatment with the test item as compared to the frequencies of the controls.
Appropriate mutagens were used as positive controls.
They induced statistically significant increases (p < 0.05) in cells with structural chromosome aberrations.

Applicant's summary and conclusion

Conclusions:

Under the experimental conditions reported, the test item did not induce structural chromosome aberrations in vitro. Therefore, the test item is considered to be non-clastogenic in this chromosome aberration test neither with nor without S9 mix.