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: Crocin improves lipid dysregulation in subacute diazinon exposure through ERK1 / 2 pathway in rat liver .
### Output Text:
<span class="chemical">Crocin</span> improves lipid dysregulation in subacute <span class="chemical">diazinon</span> exposure through ERK1 / 2 pathway in rat liver . 