18828
Both behavioral and electrophysiological assays showed that the biological activity observed for the racemic mixture was reproduced only with ( 2R ) - IKM - 159 , whereas the ( 2S ) - counterpart was inactive in both assays .
 Chemical: ( 2R ) - IKM - 159
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: ( 2R ) - IKM - 159