2-methylglutaric acid

Endpoint summary

Additional information

Performed studies

In vitro Bacterial mutagenicity (Ames Test)

2-Methylglutaric acid has been evaluated in a bacterial mutagenicity assay (OECD 471) using four strains of Salmonella typhimurium (TA1535, TA1537, TA98, TA100) and one strains of Escherichia coli (WP2PuvrA). 

In the different experiments, the 2-Methylglutaric acid did not show any potential of mutagenicity with and without metabolic activation.

 

In vitro Clastogenic Potential:

2-Methylglutaric acid has been evaluated in a chromosome aberration test (OECD 473), with and without metabolic activation. Some positive results were observed in presence of low pH and high cytotoxicity. When 2-Methylglutaric acid was neutralized, no more cytotoxicity was observed and results were negative up to maximum tested concentrations. It is concluded that 2 -Methylglutaric acid does not present clastogenic potential with or without metabolic activation.

 

In vitro mammalian cell mutagenicity:

2-Methylglutaric acid was tested in the L5178Y TK +/- mouse lymphoma gene mutation assay (OECD 476) in the presence of an auxiliary metabolising system (S9). Some positive results were observed in presence of low pH and high cytotoxicity. When 2-Methylglutaric acid was neutralized, no more cytotoxicity was observed and results were negative up to the maximum tested concentrations. It is concluded that 2-Methylglutaric acid does not present mutagenic potential both in the presence and in the absence of S9-mix.

In vivo Mutagenicity

2-Methylglutaric was assessed in the in vivo micronucleus test in the mouse (OECD 474). The test substance was formulated in physiological saline water, which was used as the vehicle control. The test substance was administered orally by gavage at up to 2000 mg/kg for the male and 1750 mg/kg for the female. Not treatment related clinical signs or mortality were noted.

No biological relevant increase in the mean frequency of micronucleated polychromatic erythrocytes was observed in the bone marrow of animals treated compared to the vehicle treated animals.

It is concluded that 2-Methylglutaric acid is not clastogenic or aneugenic in the bone marrow micronucleus test when sampled at 24 and 48 hours post dosing of male and female mice up to a dose of 2000 and 1750 mg/kg, respectively (maximum recommended/tolerated dose in accordance with current regulatory guidelines in males and females, respectively)

Discussion

While Ames test was clearly negative, some positive results were observed in in vitro chromosome aberration test (OECD 473) and mouse lymphoma gene mutation assay (OECD 476) but only with low pH (around 6) and in presence of strong cytotoxicity, moreover in both case, maximum test concentration was limited by cytotoxicity. In order to determine if these positive results were linked to pH, positives conditions have been re-tested with previously neutralized 2-Methylglutaric acid. In both test, neutralization suppressed cytotoxicity allowing to test the substance up to the maximum recommended dose in the guidelines (i.e. 0.01M). Neutralized 2-Methylglutaric acid induced no positive response in chromosome aberration test (OECD 473) and mouse lymphoma gene mutation assay (OECD 476). It is therefore concluded that the observed positive responses were artefacts caused by low pH. This conclusion is supported by the negative response obtained in the in vivo micronucleus test in the mouse (OECD 474) performed with 2-Methylglutaric acid.

Justification for selection of genetic toxicity endpoint
Three in vitro and one in vivo genotoxicity studies are considered to be key studies covering the mutagenic and clastogenic endpoints of genotoxicity.

Short description of key information:
The four performed GLP studies did not suggest any genotoxicity potential for the 2-Methyglutaric acid.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on absence of mutagenicity in the in vitro and in vivo tests, it is concluded that 2-Methylglutaric acid is not genotoxic. Therefore no classification is required according to the EU legislation (Directive 67/548/EEC and CLP regulation 1272/2008).