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: Biological evaluation suggested that conjugates ( ED1 - ED4 ) retained comparable analgesic and antiinflammatory activities with remarkably reduced ulcerogenicity as compared to their parent drug - - etodolac .
### Output Text:
Biological evaluation suggested that conjugates ( ED1 - ED4 ) retained comparable analgesic and antiinflammatory activities with remarkably reduced ulcerogenicity as compared to their parent drug - - <span class="chemical">etodolac</span> . 