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 data suggest that HOMER1 rs4704559 G allele has a protective role for the development of levodopa adverse effects .
### Output Text:
Our data suggest that HOMER1 rs4704559 G allele has a protective role for the development of <span class="chemical">levodopa</span> adverse effects . 