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: Scopolamine ( 10 mg / kg ) and pentobarbital ( 5 mg / kg ) prevented development of pilocarpine - induced behavioral seizure but MK - 801 ( 0 . 5 mg / kg ) did not .
### Output Text:
<span class="chemical">Scopolamine</span> ( 10 mg / kg ) and <span class="chemical">pentobarbital</span> ( 5 mg / kg ) prevented development of <span class="chemical">pilocarpine</span> - induced behavioral seizure but <span class="chemical">MK - 801</span> ( 0 . 5 mg / kg ) did not . 