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: Cells were pretreated with maltolyl p - coumarate , before exposed to amyloid beta peptide ( 1 - 42 ) , glutamate or H2O2 .
### Output Text:
Cells were pretreated with <span class="chemical">maltolyl p - coumarate</span> , before exposed to <span class="chemical">amyloid beta peptide ( 1 - 42 )</span> , <span class="chemical">glutamate</span> or <span class="chemical">H2O2</span> . 