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Molecular docking showed that VA binding is favored by sandwich pi stacking with Tyr - 181 and Phe - 89 .
 Chemical: Tyr; Chemical: Phe
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: Tyr; Chemical: Phe