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: Thus , three of six patients had their menstrual irregularity successfully corrected with bromocriptine .
### Output Text:
Thus , three of six patients had their menstrual irregularity successfully corrected with <span class="chemical">bromocriptine</span> . 