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: Reduced progression of adriamycin nephropathy in spontaneously hypertensive rats treated by losartan .
### Output Text:
Reduced progression of <span class="chemical">adriamycin</span> nephropathy in spontaneously hypertensive rats treated by <span class="chemical">losartan</span> . 