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: Chronic enalapril treatment reduced blood pressure without reducing albuminuria in group 4 .
### Output Text:
Chronic <span class="chemical">enalapril</span> treatment reduced blood pressure without reducing albuminuria in group 4 . 