14454
Radioing in on NPY : Attachment of a [ 2 , 3 - ( 3 ) H ] propionyl group through an appropriate linker to the guanidine group of an ( S ) - argininamide - type neuropeptide Y ( NPY ) Y ( 2 ) receptor antagonist resulted in a subtype - selective radioligand .
 [ 2 , 3 - ( 3 ) H ] propionyl, guanidine, ( S ) - argininamide
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 [ 2 , 3 - ( 3 ) H ] propionyl, guanidine, ( S ) - argininamide