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: To develop a novel and effective drug that could enhance cognitive function and neuroprotection , we newly synthesized maltolyl p - coumarate by the esterification of maltol and p - coumaric acid .
### Output Text:
To develop a novel and effective drug that could enhance cognitive function and neuroprotection , we newly synthesized <span class="chemical">maltolyl p - coumarate</span> by the esterification of <span class="chemical">maltol</span> and <span class="chemical">p - coumaric acid</span> . 