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: Oral administration of 2 , 5 - di - O - acetyl - D - glucaro - 1 , 4 - 6 , 3 - dilactone protected rats against renal failure induced by kanamycin - dextran .
### Output Text:
Oral administration of <span class="chemical">2 , 5 - di - O - acetyl - D - glucaro - 1 , 4 - 6 , 3 - dilactone</span> protected rats against renal failure induced by <span class="chemical">kanamycin</span> - dextran . 