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: Biochemical analysis of brain revealed that the reserpine treatment significantly increased lipid peroxidation and decreased levels of superoxide dismutase ( SOD ) , catalase ( CAT ) and glutathione reductase ( GSH ) , an index of oxidative stress process .
### Output Text:
Biochemical analysis of brain revealed that the <span class="chemical">reserpine</span> treatment significantly increased lipid peroxidation and decreased levels of <span class="chemical">superoxide</span> dismutase ( SOD ) , catalase ( CAT ) and <span class="chemical">glutathione</span> reductase ( GSH ) , an index of oxidative stress process . 