5509
Based on the existing reports regarding the antiplatelet aggregation activity of hydrazone derivatives , a series of indole hydrazone derivatives were considered as potential antiplatelet agents and synthesized .
 hydrazone, indole hydrazone
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 hydrazone, indole hydrazone