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: Additionally , thiobarbituric acid reactive substances ( TBARSs ) and superoxide production were measured in submitochondrial particles of the prefrontal cortex , hippocampus , striatum and amygdala .
### Output Text:
Additionally , <span class="chemical">thiobarbituric acid</span> reactive substances ( TBARSs ) and <span class="chemical">superoxide</span> production were measured in submitochondrial particles of the prefrontal cortex , hippocampus , striatum and amygdala . 