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: Time course of lipid peroxidation in puromycin aminonucleoside - induced nephropathy .
### Output Text:
Time course of lipid peroxidation in <span class="chemical">puromycin aminonucleoside</span> - induced nephropathy . 