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: Our results demonstrate that both cisplatin and paclitaxel cause early mitochondrial impairment with loss of membrane potential and induction of autophagic vacuoles in neurons .
### Output Text:
Our results demonstrate that both <span class="chemical">cisplatin</span> and <span class="chemical">paclitaxel</span> cause early mitochondrial impairment with loss of membrane potential and induction of autophagic vacuoles in neurons . 