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: Concomitant curcumin administration prevented the cognitive impairment and decreased the increased oxidative stress induced by these antiepileptic drugs .
### Output Text:
Concomitant <span class="chemical">curcumin</span> administration prevented the cognitive impairment and decreased the increased oxidative stress induced by these antiepileptic drugs . 