Structure-alert category

This phase classifies chemicals passing from the previous phase into active and inactive categories. Three structural alerts (Section IV.B), seven pharmacophore queries (Section IV.C), and the Decision Tree classification model (Section IV.D) were used in parallel to discriminate active from inactive chemicals. To ensure the lowest false negative rate in this phase, a chemical predicted to be active by any of these 11 models is subsequently evaluated in Phase III, whereas only those predicted to inactive by all these models are eliminated for further evaluation. Since structural alert, pharamacophore and Decision Tree methods incorporate and weight differently the various structural features that endow a chemical with the ability to bind the ER the combined outputs derived... 

Hewitt M, Enoch SJ, Madden JC, Przybylak KR, Cronin MT (2013) Hepatotoxicity a scheme for generating chemical categories for read-across, structural alerts and insights into mechanism(s) of action. CritRev Toxicol 43, 537-58. 

Category 3 Alerting structure— unique structure, unknown mutagenic potential... 

Category 4 Alerting structure—but analogous to an established nonmutagen... 

---