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: Curcumin ameliorates cognitive dysfunction and oxidative damage in phenobarbitone and carbamazepine administered rats .
### Output Text:
<span class="chemical">Curcumin</span> ameliorates cognitive dysfunction and oxidative damage in <span class="chemical">phenobarbitone</span> and <span class="chemical">carbamazepine</span> administered rats . 