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: Effect of green tea and vitamin E combination in isoproterenol induced myocardial infarction in rats .
### Output Text:
Effect of <span class="chemical">green tea</span> and <span class="chemical">vitamin E</span> combination in <span class="chemical">isoproterenol</span> induced myocardial infarction in rats . 