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The present study revealed that the methyl group on the gamma - lactone moiety is critical to the potent inhibition of complex I by natural acetogenins .
 Chemical: methyl; Chemical: gamma - lactone; Chemical: acetogenins
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: methyl; Chemical: gamma - lactone; Chemical: acetogenins