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: Effect of direct intracoronary administration of methylergonovine in patients with and without variant angina .
### Output Text:
Effect of direct intracoronary administration of <span class="chemical">methylergonovine</span> in patients with and without variant angina . 