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: Both agents show substantial clinical efficacy , with reductions in total cholesterol of over 30 % and in LDL - cholesterol of 40 % in clinical studies .
### Output Text:
Both agents show substantial clinical efficacy , with reductions in total <span class="chemical">cholesterol</span> of over 30 % and in LDL - <span class="chemical">cholesterol</span> of 40 % in clinical studies . 