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Methyl Sulfate - Negative- Equivocal

Compound Details

Compound name: Methyl Sulfate

Molecular formula: CH4O4S

Average mass: 112.105

SMILES formula: S(=O)(=O)(O)OC


In Silico Assessment

The compound was assessed using the ICH M7 functionality in Nexus (v2.1) which contains the expert rule-based system Derek Nexus (v5.0) and the statistical-based system Sarah Nexus (v2.0). The following predictions were observed:

Mapping this onto Lhasa's Decision Matrix:


Conservatively could assign as positive. May conclude negative if strong evidence showing feature driving a 'no prediction' is present in the same context in known negative examples (without deactivating features).

Prediction Details:

The following prediction details were gathered:

  • Derek Nexus – Inactive with no misclassified or unclassified features.
  • Sarah Nexus – Equivocal prediction with examples which chiefly show dialkyl sulphates as positive but monoalkyl sulphates as negative.

Expert review:

The following is an expert assessment on the evidence gathered:

Derek Nexus

  • No alerts fired.
  • The lack of misclassified features shows that none of the features of this compound were found to be in non-alerting mutagens in the Lhasa Ames Test reference set.
  • The inactive prediction also outlines the lack of unclassified features. This demonstrates that all features of the compound were found in the Lhasa Ames Test reference set.

Sarah Nexus

  • The compound is predicted to be equivocal. The compound is in the domain of the model, however no local hypotheses have been identified.
  • A prediction has been made based on the activity of the 8 most similar examples from the training set.

Expert call:

Having reviewed the prediction details (and the predictions for analogues), the following call has been suggested:

Negative – Derek Nexus made a confident negative prediction. Sarah Nexus returned an equivocal prediction using the 8 most similar compounds from its training set. The compounds closest in similarity to the query compound have a negative outcome, so there is reasonable evidence to suggest that methyl sulfate has a negative outcome. An expert would also comment that mechanistically monoalkyl sulphates are not nucleophilic. This is sufficient evidence to provide an overall call of negative.


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