24586
Hydrophobic residues , such as propyl or butyl , in the para - position ( not ortho or meta ) of the A - ring and a meta - pyridyl group as B - ring significantly improve activity .
 propyl, butyl, meta - pyridyl
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 propyl, butyl, meta - pyridyl