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: In the propranolol group , serum potassium and uric acid levels rose in both sexes , but the urea level rose significantly in women only .
### Output Text:
In the <span class="chemical">propranolol</span> group , serum <span class="chemical">potassium</span> and <span class="chemical">uric acid</span> levels rose in both sexes , but the <span class="chemical">urea</span> level rose significantly in women only . 