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: Vitamin E supplementation ameliorated hypertension , lowered plasma MDA concentration , and raised urinary NOx excretion while significantly lowering vascular , but not renal , tissue eNOS and iNOS expression .
### Output Text:
<span class="chemical">Vitamin E</span> supplementation ameliorated hypertension , lowered plasma <span class="chemical">MDA</span> concentration , and raised urinary NOx excretion while significantly lowering vascular , but not renal , tissue eNOS and iNOS expression . 