18838
These studies revealed a promising lead compound , 17b , that exhibited nanomolar potency against T . brucei ( EC50 = 27 nM for T . b . brucei , 7 nM for T . b . rhodesiense , and 2 nM for T . b . gambiense ) with excellent selectivity for parasite cells relative to mammalian cell lines ( EC50 > 25 mu M ) .
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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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