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: Cardioprotective effect of salvianolic acid A on isoproterenol - induced myocardial infarction in rats .
### Output Text:
Cardioprotective effect of <span class="chemical">salvianolic acid A</span> on <span class="chemical">isoproterenol</span> - induced myocardial infarction in rats . 