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: This view supports the contention that the liver and muscle are independent sites of prednisolone action .
### Output Text:
This view supports the contention that the liver and muscle are independent sites of <span class="chemical">prednisolone</span> action . 