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 levodopa - treated MPTP - lesioned marmoset was used as a model of neuropsychiatric symptoms in PD patients .
### Output Text:
The <span class="chemical">levodopa</span> - treated <span class="chemical">MPTP</span> - lesioned marmoset was used as a model of neuropsychiatric symptoms in PD patients . 