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: Acute administration of A - 86929 was as efficacious in alleviating MPTP - induced parkinsonism as levodopa and LY - 171555 , but was less likely to reproduce the levodopa - induced dyskinesias in these animals than with either LY - 171555 or subsequent challenge of levodopa .
### Output Text:
Acute administration of <span class="chemical">A - 86929</span> was as efficacious in alleviating <span class="chemical">MPTP</span> - induced parkinsonism as <span class="chemical">levodopa</span> and <span class="chemical">LY - 171555</span> , but was less likely to reproduce the <span class="chemical">levodopa</span> - induced dyskinesias in these animals than with either <span class="chemical">LY - 171555</span> or subsequent challenge of <span class="chemical">levodopa</span> . 