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: Animals were evaluated for parkinsonian disability , dyskinesia and on - time ( motor fluctuations ) and neuropsychiatric - like behaviors on Day 0 ( prior to levodopa ) and on Days 1 , 7 , 13 , 27 and 30 of treatment using post hoc DVD analysis by a trained rater , blind to the treatment day .
### Output Text:
Animals were evaluated for parkinsonian disability , dyskinesia and on - time ( motor fluctuations ) and neuropsychiatric - like behaviors on Day 0 ( prior to <span class="chemical">levodopa</span> ) and on Days 1 , 7 , 13 , 27 and 30 of treatment using post hoc DVD analysis by a trained rater , blind to the treatment day . 