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: Since AAP , AMI and DOX undergo biotransformation and are known to produce damaging radicals in vivo , the protection by GSPE may be linked to both inhibition of metabolism and / or detoxification of cytotoxic radicals .
### Output Text:
Since <span class="chemical">AAP</span> , <span class="chemical">AMI</span> and <span class="chemical">DOX</span> undergo biotransformation and are known to produce damaging radicals in vivo , the protection by <span class="chemical">GSPE</span> may be linked to both inhibition of metabolism and / or detoxification of cytotoxic radicals . 