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: Trimipramine ( TRI ) , which shows a clinical antidepressant activity , is chemically related to imipramine but does not inhibit the reuptake of noradrenaline and 5 - hydroxytryptamine , nor does it induce beta - adrenergic down - regulation .
### Output Text:
<span class="chemical">Trimipramine</span> ( <span class="chemical">TRI</span> ) , which shows a clinical <span class="chemical">antidepressant</span> activity , is chemically related to <span class="chemical">imipramine</span> but does not inhibit the reuptake of <span class="chemical">noradrenaline</span> and <span class="chemical">5 - hydroxytryptamine</span> , nor does it induce beta - adrenergic down - regulation . 