25480
To improve the efficacy of the conformationally restricted BACE1 inhibitors , structural modifications were investigated using two strategies : ( a ) modification of the terminal aromatic ring and ( b ) insertion of a spacer between the aromatic rings .
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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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