19597
In contrast to prior studies , removal of the N - 7 of the nucleobase entirely negates anti - HCV activity compared to the 2 ' - C - methyl - 6 - O - methylguanosine analogues .
 N, nucleobase, 2 ' - C - methyl - 6 - O - methylguanosine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 N, nucleobase, 2 ' - C - methyl - 6 - O - methylguanosine