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: Acute interstitial nephritis due to nicergoline ( Sermion ) .
### Output Text:
Acute interstitial nephritis due to <span class="chemical">nicergoline</span> ( <span class="chemical">Sermion</span> ) . 