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: Role of mangiferin on biochemical alterations and antioxidant status in isoproterenol - induced myocardial infarction in rats .
### Output Text:
Role of <span class="chemical">mangiferin</span> on biochemical alterations and antioxidant status in <span class="chemical">isoproterenol</span> - induced myocardial infarction in rats . 