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: It is concluded that curcumin is able to attenuate in vivo maleate - induced nephropathy and in vitro cell damage .
### Output Text:
It is concluded that <span class="chemical">curcumin</span> is able to attenuate in vivo <span class="chemical">maleate</span> - induced nephropathy and in vitro cell damage . 