20884
The main proposed metabolic pathways in various in vitro systems were N - oxidation of the pyridine and / or pyrimidine ring and conversion to 4 - pyrimidone and pyrimidine - 2 , 4 - dione .
 Chemical: N; Chemical: pyridine; Chemical: pyrimidine; Chemical: 4 - pyrimidone; Chemical: pyrimidine - 2 , 4 - dione
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: N; Chemical: pyridine; Chemical: pyrimidine; Chemical: 4 - pyrimidone; Chemical: pyrimidine - 2 , 4 - dione