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: In the present study , we investigated whether maltolyl p - coumarate could improve cognitive decline in scopolamine - injected rats and in amyloid beta peptide ( 1 - 42 ) - infused rats .
### Output Text:
In the present study , we investigated whether <span class="chemical">maltolyl p - coumarate</span> could improve cognitive decline in <span class="chemical">scopolamine</span> - injected rats and in <span class="chemical">amyloid beta peptide ( 1 - 42 )</span> - infused rats . 