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: The hyperactivity induced by D - amphetamine ( 10 mumol / kg ) was significantly reduced by DSP4 pretreatment .
### Output Text:
The hyperactivity induced by <span class="chemical">D - amphetamine</span> ( 10 mumol / kg ) was significantly reduced by <span class="chemical">DSP4</span> pretreatment . 