2423
Serum and hippocampus superoxide dismutase ( SOD ) levels were determined by measuring its ability to inhibit the photoreduction of nitroblue tetrazolium .
 superoxide, nitroblue tetrazolium
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 superoxide, nitroblue tetrazolium