23790
Synthesis and biological evaluation of potent histamine H3 receptor antagonists incorporating a hydroxyl function are described .
 Chemical: histamine; Chemical: hydroxyl
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: histamine, hydroxyl 
Answer:
 Chemical: histamine; Chemical: hydroxyl