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: The catechol and hydroquinone metabolites , NCQ436 and NCQ344 , induced apoptosis in HL60 and HBMP cells in a time - and concentration dependent manner , while the phenols , NCR181 , FLA873 , and FLA797 , and the derivatives formed by oxidation of the pyrrolidine ring , FLA838 , NCM001 , and NCL118 , had no effect .
### Output Text:
The <span class="chemical">catechol</span> and <span class="chemical">hydroquinone</span> metabolites , <span class="chemical">NCQ436</span> and <span class="chemical">NCQ344</span> , induced apoptosis in HL60 and HBMP cells in a time - and concentration dependent manner , while the <span class="chemical">phenols</span> , NCR181 , FLA873 , and <span class="chemical">FLA797</span> , and the derivatives formed by oxidation of the <span class="chemical">pyrrolidine</span> ring , FLA838 , NCM001 , and NCL118 , had no effect . 