15052
A structure - activity relationship study was carried out to develop compounds with improved efficacy against HIV - 1 and 49 indolizine derivatives of three categories were designed and synthesized .
 Chemical: indolizine
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: indolizine