L-Valine, N-(1-oxopentyl)-N-[[2'-(2H-tetrazol-5-yl)[1,1'-biphenyl]-4-yl]methyl]-, phenylmethyl ester

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Compound is considerate as non-genotoxic.

PBS 859 DS exerted no toxic effect on the growth of the bacteria.

Four GLP genotoxicity and mutagenicity studies were performed. An in vitro chromosome aberration study in Chinese hamster ovary (CHO) cells demonstrated weak clastogenic effects.

In the micronucleus test, the percentage of PCEs was not decreased in any of the dose groups. No signs of bone marrow toxicity were observed.

In all dosage groups assessed at the different periods post treatment, no statistically significant increase in the number of micronucleated polychromatic erythrocytes was observed when compared with the respective negative control group.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15.6.1994 - 21.6.1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

no E. coli strain or Salmonella typhimurium TA 102 was tested

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Target gene:

his operon

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

rat-liver post mitochondrial supernatant (S9 fraction)

Test concentrations with justification for top dose:

61.73, 185.19, 555.56, 1666.67 and 5000 μg/plate with and without metabolic activation for all strains and additionally 20.58 μg/plate for TA 100 with and without metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: with S9: 2-Aminoanthracene (2.5 μg/plate; TA 98, TA 100, TA 1537) and Cyclophosphamide (400 μg/plate; TA 1535); without S9: Sodium azide (5 μg/plate; TA 100, TA 1535), 2-Nitrofluorene (20 μg/plate; TA 98), 9-Aminoacridine (150 μg/plate; TA 1537)

Details on test system and experimental conditions:

The histidine-auxotrophic strains of Salmonella typhimurium (TA 98, TA 1535, TA 1537) were obtained from Prof B. Ames, Berkeley, USA Strain TA 100 was obtained from Dr. M. Schupbach, Hoffmann-La Roche Limited, Basel, Switzerland.
Preparation of the bacterial cultures
Inoculates from frozen master copies were set up monthly. They were grown in liquid nutrient broth medium (NB-medium) overnight and then plated on NB-agar. After incubation, single colonies were taken from the plates, grown overnight in liquid NB-medium and then used for the experiment.
Control of the genotype of the strains
The characteristics of the strains were checked monthly. Histidine-auxotrophy of the Salmonella strains was demonstrated by the requirement for L-histidine. The presence of the rfa character was assayed by the sensitivity for crystal-violet. The deletion of the uvrB gene (TA 98, TA 100, TA 1535 and TA 153 7) was demonstrated by the sensitivity for UV-light. The Salmonella strains containing the R-factor (TA 98 and TA 100) were additionally checked for ampicillin resistance. Furthermore, all strains were checked for their characteristic reversion properties with known mutagens (positive controls).

Evaluation criteria:

A test is considered acceptable if the mean colony counts of the negative control values of all strains are within the acceptable ranges and if the results of the positive controls meet the criteria for a positive response. In either case the final decision is based on the scientific judgement of the Study Director.

Statistics:

A statistical analysis of the test data was not performed. At present the use of statistical methods concerning this particular test system is not generally recommended

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not applicable

Positive controls validity:

valid

Conclusions:

In the experiments performed with and without metabolic activation, again after treatment of strains TA 98, TA 100, TA 1535 and TA 1537 with PBS 859 DS no increase in the incidence of histidineprototrophic mutants was observed in comparison with the negative control

In the mutagenicity tests normal background growth was observed with all strains at all concentrations. The numbers of revertant colonies were not reduced with increasing concentration.
Therefore, the test substance exerted no toxic effect on the growth of the bacteria.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Four GLP genotoxicity and mutagenicity studies were performed. An in vitro chromosome aberration study in Chinese hamster ovary (CHO) cells demonstrated weak clastogenic effects. However, an in vivo micronucleus study in rats and a DNA damage and repair/ unscheduled DNA synthesis study in in vivo rat hepatocytes delivered negative results for various genotoxicity endpoints and the compound is considerate as non-genotoxic.

Justification for classification or non-classification

In the experiments performed with and without metabolic activation, again after treatment of strains TA 98, TA 100, TA 1535 and TA 1537 with PBS 859 DS no increase in the incidence of histidineprototrophic mutants was observed in comparison with the negative control

In the mutagenicity tests normal background growth was observed with all strains at all concentrations. The numbers of revertant colonies were not reduced with increasing concentration.