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: The ethanolic extract of Daucus carota seeds ( DCE ) was administered orally in three doses ( 100 , 200 , 400 mg / kg ) for seven successive days to different groups of young and aged mice .
### Output Text:
The ethanolic <span class="chemical">extract of Daucus carota seeds</span> ( <span class="chemical">DCE</span> ) was administered orally in three doses ( 100 , 200 , 400 mg / kg ) for seven successive days to different groups of young and aged mice . 