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: In this study , we investigated the effects of Re , Rg1 , and Rb1 ginsenosides , the bioactive components of ginseng , on OIH .
### Output Text:
In this study , we investigated the effects of <span class="chemical">Re , Rg1 , and Rb1 ginsenosides</span> , the bioactive components of ginseng , on OIH . 