22799
Cyclization and modifications of Retro - 2 led to a compound with roughly 100 - fold improvement of the EC50 against Shiga toxin cytotoxicity measured in a cell protein synthesis assay .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None