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 level of lipid peroxidation was higher and the reduced glutathione concentration was lower in the MA - treated rats .
### Output Text:
The level of lipid peroxidation was higher and the reduced <span class="chemical">glutathione</span> concentration was lower in the <span class="chemical">MA</span> - treated rats . 