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: A 65 - year - old woman with adult - onset diabetes treated with chlorpropamide ( Diabenese ) had a toxic optic neuropathy that resolved with discontinuation of chlorpropamide therapy .
### Output Text:
A 65 - year - old woman with adult - onset diabetes treated with <span class="chemical">chlorpropamide</span> ( <span class="chemical">Diabenese</span> ) had a toxic optic neuropathy that resolved with discontinuation of <span class="chemical">chlorpropamide</span> therapy . 