1H-Benz[e]indolium, 2-[2-[2-chloro-1-[2-[1,3-dihydro-1,1-dimethyl-3-(4-sulfobutyl)-2H-benz[e]indol-2-ylidene]ethylidene]-1H-inden-3-yl]ethenyl]-1,1-dimethyl-3-(4-sulfobutyl)-, inner salt

Biodegradation in water: screening tests

Description of key information

No experimental biodegradation test has been performed. Read-across is done to a similar structure (CAS 1073607-50-7). This substance is considered as non biodegradable. Moreover QSARs such as VEGA and Biowin consider both substance as non biodegradable. As a result this substance is considered as non biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Read-across justification

Biodegradation data on v516690 (IUPAC name 4-[2-[(E)-2-[(3E)-2-chloro-3-[(2E)-2-[1,1-dimethyl-3-(4-sulfobutyl)benzo[e]indol-2-ylidene]ethylidene]inden-1-yl]vinyl]-1,1-dimethyl-benzo[e]indol-3-ium-3-yl]butane-1-sulfonate) is a data requirement for REACH dossiers 1-10 tonnes/year. Since information on this endpoint is lacking for this substance, read-across to the structurally similar substance infrazam (EC number: 700-626-0; CAS number: 1073607-50-7) is suggested. RAAF scenario 2 is applicable since the hypothesis is based on a different compound having the same type of effect. 

The target substance has an additional aromatic group in comparison to infrazam.

Based on the OECD QSAR toolbox profiling application, both substances have a similar profile: both are not considered estrogen receptor binders, are not expected to bind to proteins (OASIS v1.1 and OECD) and fall within the same Cramer class (Class III) (possible significant toxicity).

Regarding in vitro mutagenicity (Ames alerts by ISS) no alert was found for both substances.

However, both substances have a H-acceptor-path3-H-acceptor alert (in vivo mutagenicity alerts by ISS). This alert explores the possibility that a chemical could potentially interact with DNA and/or proteins via non-covalent binding (Snyder et al. 2006[1]).

The only difference between the source and target substance in OECD QSAR toolbox is a structural alert for genotoxic carcinogenicity, only for v516690 based on alkenylbenzene presence. However the alkenyl-group should be available to react which is not the case, since the alkenyl group is part of a ring. This difference can therefore be refuted and is not considered relevant.

 

Biotransformation of both substances can be expected. OECD QSAR toolbox did not find any observed metabolites, but renders only simulated metabolites. The mechanism of biotransformation is expected to be very similar and not trigger any additional toxicity.

 

The outcome of Biowin 4.10 show that both substances are not biodegradable and consequently show that both substances behave similarly.

Moreover the water solubility and Log Kow are very similar. Both substances have a water solubility around 1-10 g/L. The Log Kow is 1.9 for the target substance v516690 and 1.2 for infrazam.

 

A readily biodegradability test is available for infrazam. Since the read-across substance is structurally very similar and no additional alerts have been found in OECD QSAR toolbox, it can be concluded that v516690 has a similar biodegradation.  

 

 

[1]Snyder, R. D., Ewing, D. and Hendry, L. B. 2006. DNA intercalative potential of marketed drugs testing positive inin vitrocytogenetics assays.Mutat. Res.609, 47-59.