Registration Dossier

Administrative data

Endpoint:
biodegradation in soil, other
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Justification for type of information:
1. EAWAG-BBD Pathway Prediction System

1.1 Model description
The EAWAG-BBD Pathway Prediction System (also known as Minnesota Pathway Prediction System) is a web-based tool (http://eawag-bbd.ethz.ch/predict/) and can be used free of charge.
Purpose and Scope:
The model predicts plausible pathways for microbial degradation of chemical compounds. Predictions use biotransformation rules, based on reactions found in the EAWAG-BBD database or in the scientific literature. A list of all rules is available and comprises currently 332 different pathways.
PPS predictions are most accurate for compounds that are:
• similar to compounds whose biodegradation pathways are reported in the scientific literature;
• in environments exposed to air, in moist soil or water, at moderate temperatures and pH, with no competing chemicals or toxins; and
• the sole source of energy, carbon, nitrogen, or other essential element for the microbes in these environments, rather than present in trace amounts.

There are a number of chemical classes that should not be investigated using the current version of the Pathway Prediction System. Important classes of chemicals whose biodegradation should not be predicted are listed below.
This list is based on a similar list developed for the PBT System by the Environmental Science Center under contract to the Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency.
• Readily Degraded and Selected Other Compounds
• Inorganic Chemicals
• High Molecular Weight Compounds
• Chemicals with Unknown or Variable Composition
• Mixtures
• Highly Fluorinated Compounds



1.2 Validity of the Model

As described under 1.1, the model contains currently a high number (332) of different pathways described in the scientific literature. For Solvent Green 28 the model revealed the following theoretical pathways:
• 1-Hydroxy-2-unsubstituted aromatic -> 1,2-Dihydroxyaromatic (bt0014)
• Anthrone derivative -> 2-[(2-Hydroxyphenyl)methyl]benzoate derivative (bt0418)
• 1,2-Dihydroxybenzenoid w fused aliphatic ring -> 2-Oxo-3-butenoate aliphatic ring (bt0342)
As a result, the high number of pathways included in the model gave relevant pathways fitting to the substance. Furthermore, the substance is not excluded from the classes of chemicals whose biodegradation should not be predicted.

Data source

Reference
Reference Type:
other company data
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The EAWAG-BBD Pathway Prediction System (also known as Minnesota Pathway Prediction System) is a web-based tool (http://eawag-bbd.ethz.ch/predict/) which predicts plausible pathways for microbial degradation of chemical compounds. Predictions use biotransformation rules, based on reactions found in the EAWAG-BBD database or in the scientific literature. A list of all rules is available and comprises currently 332 different pathways.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Details on test material:
- SMILES: CC(C)(C)c1ccc(cc1)Nc5ccc(Nc2ccc(cc2)C(C)(C)C)c4C(=O)c3c(O)ccc(O)c3C(=O)c45
- Molecular weight: 534.64 g/mole

Results and discussion

Half-life / dissipation time of parent compound
Remarks on result:
other: EAWAG prediction system gives hints on metabolic pathways and on their likelyhood. No definitive half-lifes are obtained by the prediction.
Transformation products:
not measured
Details on transformation products:
Details of possible transformation products are described in the attached full study report.

Applicant's summary and conclusion

Conclusions:
The outcome of the pathway prediction system is that biodegradation of Solvent Green 28 is possible via the route “oxidative cleavage of the amino function”. Other routes do not occur or are rather slowly.
Executive summary:

The primary metabolism follows two possible routes which are the oxidative cleavage of the amine group and the cleavage of the anthrone ring system. The second route was found to occur “neutral”. Neutral means that this pathway is theoretically possible. EAWAG defines reaction to be neutral as follows: Possible reaction (neutral). This applies to reactions that are common but not certain to occur in every system. For example, hydrocarbon oxygenation reactions are quite possible, but may or may not be likely to occur depending on what the substrate is. These must be looked at individually. Some may be likely, some may be possible and some may be unlikely based on current knowledge.

In case of Solvent Green 28, the neutral pathway has to be understood that degradation is more unlikely than likely. This means that the first step is expected to occur slowly and subsequent secondary or tertiary pathways would not lead to relevant biodegradation and mineralization.

The other primary route of biodegradation is the oxidative cleavage of the amino function which is described to occur “likely”.  EAWAG defines reaction to be neutral as follows: Likely reaction. This is to be used when almost all bacteria can catalyze a given reaction with a functional group present in a molecule. For example, if the substrate has an ester linkage, it is often hydrolyzed by very common esterases, found both extracellularly and intracellularly. So giving an ester hydrolysis rule a score of 2 would give it a high priority but after an acid chloride hydrolysis reaction. You should also use 2 for a reaction that is significantly likely to occur once a certain intermediate has been generated. For example, aromatic ring cis-dihydrodiols are likely to be dehydrogenated to form catechols. Most organisms that make cis-dihydrodiols will also catalyze their dehydrogenation, thus the latter reaction is likely due to the linkage.