1493
Numerous lines of evidence suggest that heterocyclic compounds used as analgesic , anti - inflammatory and anti - migraine agents can be potent regulators of the nitroxidative stress and targeting free nitrogen and oxygen radicals is a very promising strategy for future pain management .
 nitrogen, oxygen
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 nitrogen, oxygen