In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Mefenamic acid , 26 ( 22 - 30 ) mg / kg , prevented seizures and protected rats from seizure - related brain damage induced by pilocarpine , 380 mg / kg .
### Output Text:
<span class="chemical">Mefenamic acid</span> , 26 ( 22 - 30 ) mg / kg , prevented seizures and protected rats from seizure - related brain damage induced by <span class="chemical">pilocarpine</span> , 380 mg / kg . 