9135
Complementary to the vindoline 6 , 5 DE ring system , compounds with 5 , 5 , 6 , 6 , and the reversed 5 , 6 membered DE ring systems were prepared .
 vindoline
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 vindoline