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: Sumatriptan succinate , a serotonin - 1 ( 5 - hydroxytryptamine - 1 ) receptor agonist , is an antimigraine drug that is reported to act by selectively constricting intracranial arteries .
### Output Text:
<span class="chemical">Sumatriptan succinate</span> , a <span class="chemical">serotonin</span> - 1 ( <span class="chemical">5 - hydroxytryptamine</span> - 1 ) receptor agonist , is an antimigraine drug that is reported to act by selectively constricting intracranial arteries . 