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: We report a venlafaxine - MAOI interaction that resulted in the serotonin syndrome in a 23 - y - old male who was taking tranylcypromine for depression .
### Output Text:
We report a <span class="chemical">venlafaxine</span> - MAOI interaction that resulted in the serotonin syndrome in a 23 - y - old male who was taking <span class="chemical">tranylcypromine</span> for depression . 