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: Acute effects of N - ( 2 - propylpentanoyl ) urea on hippocampal amino acid neurotransmitters in pilocarpine - induced seizure in rats .
### Output Text:
Acute effects of <span class="chemical">N - ( 2 - propylpentanoyl ) urea</span> on hippocampal <span class="chemical">amino acid</span> neurotransmitters in <span class="chemical">pilocarpine</span> - induced seizure in rats . 