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Most of these compounds showed significant cytotoxic activities against four human cancer cell lines ( A549 , HCT116 , MDA - MB - 231 , and CCRF - CEM ) , and the structure - activity relationships are also discussed .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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