====== Toxicity checker ======

Certain structural elements of a molecule can be responsible for toxicity. In fact, some substructural motifs occur more frequently in toxic compounds than in non-toxic ones. It therefore makes sense to eliminate such structural motifs from hits/leads as early as possible. Toxicity Checker is based on more than 100 toxic and promiscuous scaffolds. It displays an alert, when such a motif is found, and it displays the incriminated part of the molecule.

1. Go to **[[https://mcule.com/apps/toxicity-checker/|LEAD OPTIMIZATION / TOXICITY CHECKER]]**

2. Specify your existing hit/lead (either by drawing or by providing a chemical identifier such as mcule ID, SMILES, InChI or InChIKey)

3. Click on **"CHECK"**

4. If the compound contains any potential toxic substructure, **"FAIL"** message will be displayed along with your structure and the problematic motif in red

5. Go back and try to modify the problematic motif of your hit/lead

6. Click on **"CHECK"**

7. Continue the modifications, until no alert is displayed

8. You can use the other Lead Optimization tools, such as **[[https://mcule.com/apps/1-click-docking/|1-Click Docking]]** and **[[https://mcule.com/apps/property-calculator/|Property Calculator]]** to make sure other properties of the ligand are not impaired. In fact, try to improve multiple things simultaneously by checking all properties of the same idea.

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