6489
Redox parameters ( reactive oxygen production , antioxidant capacity against peroxyl radicals , glutathione - S - transferase ( GST ) activity , and glutathione ( GSH ) concentration ) did not show clear responses , but membrane damage as lipid peroxidation ( LPO ) was observed in both copper exposures .
 oxygen, peroxyl, glutathione, S, glutathione, GSH, copper
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 oxygen, peroxyl, glutathione, S, glutathione, GSH, copper