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: Results indicate that GSPE preexposure prior to AAP , AMI and DOX , provided near complete protection in terms of serum chemistry changes ( ALT , BUN and CPK ) , and significantly reduced DNA fragmentation .
### Output Text:
Results indicate that <span class="chemical">GSPE</span> preexposure prior to <span class="chemical">AAP</span> , <span class="chemical">AMI</span> and <span class="chemical">DOX</span> , provided near complete protection in terms of serum chemistry changes ( ALT , BUN and CPK ) , and significantly reduced DNA fragmentation . 