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: Prostaglandin D2 ( 0 . 5 - 3 ng / mouse ) had a hyperalgesic action on the response to a hot plate during a 3 - 60 min period after injection .
### Output Text:
<span class="chemical">Prostaglandin D2</span> ( 0 . 5 - 3 ng / mouse ) had a hyperalgesic action on the response to a hot plate during a 3 - 60 min period after injection . 