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: MK - 801 ( 0 . 1 mg / kg ) , administered 30 min before the observation test , prevented the vacuous chewing movements , tongue protrusions and catalepsy induced by reserpine .
### Output Text:
<span class="chemical">MK - 801</span> ( 0 . 1 mg / kg ) , administered 30 min before the observation test , prevented the vacuous chewing movements , tongue protrusions and catalepsy induced by <span class="chemical">reserpine</span> . 