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: Hyperglycemic effect of amino compounds structurally related to caproate in rats .
### Output Text:
Hyperglycemic effect of <span class="chemical">amino</span> compounds structurally related to <span class="chemical">caproate</span> in rats . 