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 biochemical results of brain biogenic amines of BALB / C mouse strain suggest a probable decrease of catecholamine turnover rate and / or metabolism by monoamine oxidase and a resulting increase in O - methylation of norepinephrine which may account for a behavioral depression caused by amantadine in the BALB / C mice .
### Output Text:
The biochemical results of brain biogenic <span class="chemical">amines</span> of BALB / C mouse strain suggest a probable decrease of <span class="chemical">catecholamine</span> turnover rate and / or metabolism by monoamine oxidase and a resulting increase in O - methylation of <span class="chemical">norepinephrine</span> which may account for a behavioral depression caused by <span class="chemical">amantadine</span> in the BALB / C mice . 