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: To examine a possibly deteriorating cardiotoxic effect of SM - 5887 , low - grade cardiomyopathy was induced in dogs by four courses of doxorubicin ( 1 . 5 mg / kg ) .
### Output Text:
To examine a possibly deteriorating cardiotoxic effect of <span class="chemical">SM - 5887</span> , low - grade cardiomyopathy was induced in dogs by four courses of <span class="chemical">doxorubicin</span> ( 1 . 5 mg / kg ) . 