23546
Zebra finch liver microsomes metabolized nicotine and bupropion ( CYP2B substrate ) but not coumarin ( CYP2A substrate ) .
 nicotine, bupropion, coumarin
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 nicotine, bupropion, coumarin