11577
Structure - activity relationship studies revealed that small hydrophobic group at the terminal heterocyclic ring and ortho substituents on the phenyl ring of phenylpiperazine moiety were the essential structural factors for alpha ( 1 ) - AR antagonistic activity .
 Chemical: phenylpiperazine
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: phenylpiperazine 
Answer:
 Chemical: phenylpiperazine