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: Mitochondrial impairment contributes to cocaine - induced cardiac dysfunction : Prevention by the targeted antioxidant MitoQ .
### Output Text:
Mitochondrial impairment contributes to <span class="chemical">cocaine</span> - induced cardiac dysfunction : Prevention by the targeted antioxidant <span class="chemical">MitoQ</span> . 