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 was concluded that coenzyme Q10 represents a potential therapeutic option to protect against acute cisplatin nephrotoxicity commonly encountered in clinical practice .
### Output Text:
It was concluded that <span class="chemical">coenzyme Q10</span> represents a potential therapeutic option to protect against acute <span class="chemical">cisplatin</span> nephrotoxicity commonly encountered in clinical practice . 