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: Hippocampus mice treated with GFC75 plus P400 showed an increase in AChE activity ( 63 . 30 % ) when compared with seized mice .
### Output Text:
Hippocampus mice treated with GFC75 plus P400 showed an increase in AChE activity ( 63 . 30 % ) when compared with seized mice . 