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: Stopping selegiline also significantly reduced the supine systolic and diastolic blood pressures consistent with a previously undescribed supine pressor action .
### Output Text:
Stopping <span class="chemical">selegiline</span> also significantly reduced the supine systolic and diastolic blood pressures consistent with a previously undescribed supine pressor action . 