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: It is widely used in folk medicine to treat skin diseases in both humans and animals as well as the seed decoction has been used to treat diarrheas and inflammatory diseases .
### Output Text:
It is widely used in folk medicine to treat skin diseases in both humans and animals as well as the seed decoction has been used to treat diarrheas and inflammatory diseases . 