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: Tetrandrine ( TET ) and fangchinoline ( FAN ) are two naturally occurring analogues with a bisbenzylisoquinoline structure .
### Output Text:
<span class="chemical">Tetrandrine</span> ( <span class="chemical">TET</span> ) and <span class="chemical">fangchinoline</span> ( <span class="chemical">FAN</span> ) are two naturally occurring analogues with a <span class="chemical">bisbenzylisoquinoline</span> structure . 