2-hexyldecanoic acid [4-(6-tert-butyl-7-chloro-1H-pyrazolo[1,5-b][1,2,4]triazol-2-yl)phenylcarbamoyl]methylester

Endpoint summary

Additional information

The mutagenic potential of 2-hexyldecanoic acid [4-(6-tert-butyl-7-chloro-1H-pyrazolo[1,5-b][1,2,4] triazol-2-yl)phenylcarbamoyl]methylester (UM-235) was assessed in threein vitro tests.

A bacterial reverse mutation assay (Ames test) was performed using UM-235, according to OECD 471 (Buskens, 2004). The plate incorporation method was applied using S. typhimurium strains TA 100, TA98, TA1535 and TA1537 and E. coli WP2 uvrA at concentrations up to 333 µg/plate, with and without metabolic activation. Because of precipitation seen 333 µg/plate was the highest concentration tested. Two independent experiments were conducted; the first using 5% S9-mix for metabolic activation and the second using 10% S9-mix. The test substance did not induce mutations in any of the S. typhimurium strains or in E. coli WP2 uvrA with or without metabolic activation. No cytotoxic effects were observed up to and including the highest concentration tested of 333 μg/plate. The positive controls were shown to be valid.

 

In a mammalian cell gene mutation test performed according to OECD 476, Chinese hamster lung V79 cells were exposed to UM-235 (Lazová, 2012). In two independent experiments, V79 cells were exposed to concentrations from 25 - 400 µg/mL. The upper dose range was limited by precipitation of the test substance in the culture medium from 500 µg/mL while no precipitation was observed in the main experiments. The test substance did not cause an increase in gene mutation levels, with or without metabolic activation in the first experiment. In the second experiment without metabolic activation a significant increase in mutation frequency could be observed for 50 µg/mL. However, since this increase was not greater than 3-fold of the negative control, there was no dose-dependency and it was not identified in experiment one, it was considered not to be a mutagenic effect caused by the test substance.

There was no cytotoxicity up to and including the highest dose level of 400 µg/mL and the positive controls induced significant increases in mutation frequency. In conclusion, UM-235 did not induce gene mutationsin vitro at the HPRT locus of V79 Chinese hamster lung cells when tested under the conditions of this study.

 

The potential of UM-235 to induce chromosomal aberrations was tested with cultured human peripheral lymphocytes, in a study performed according to OECD 473 (Buskens, 2004). Lymphocytes were exposed to the test substance in two independent experiments at concentrations of 10, 33 and 100 µg/mL. The highest concentration tested was chosen based on the solubility of the substance in cell culture medium. Precipitation of the test substance was observed at the highest dose, thereby limiting the dose range that could be tested. In the first experiment a short-term treatment (3 hours) was performed with a 24-hour harvest time, in the absence and presence of metabolic activation. In the second experiment short-term treatment (3 hours + 24-hour harvest time) was again applied, with metabolic activation. In addition, a 24-hour treatment with 24- hour harvest time and a 48-hour treatment with 48-hour harvest time without metabolic activation were performed. There were no increases in chromosome aberrations. No cytotoxic effects were observed at any dose level and the positive controls induced significant increase in chromosomal aberrations. Therefore, the test substance is not clastogenic in human lymphocytes under the experimental conditions of this study.

 

2-hexyldecanoic acid [4-(6-tert-butyl-7-chloro-1H-pyrazolo[1,5-b][1,2,4] triazol-2-yl) phenylcarbamoyl]methylester showed no evidence of clastogenic and mutagenic potential with and without metabolic activation in 3in vitrotest systems.

Justification for selection of genetic toxicity endpoint
No study was selected, since all available in vitro genetic toxicity studies were negative.

Short description of key information:
In vitro:
Bacterial reverse mutation assay, Ames test (OECD 471): negative
Mammalian cell gene mutation test, V79 Chinese Hamster lung cells (OECD 476): negative
Mammalian cytogenetic test, chromosome aberrations, cultured human peripheral lymphocytes (OECD 473): negative

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The available data on genetic toxicity of the test substance do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.