21033
Mixtures of drug and the amino acids arginine , phenylalanine , tryptophan and tyrosine were prepared by vibrational ball milling .
 Chemical: amino acids; Chemical: arginine; Chemical: phenylalanine; Chemical: tryptophan; Chemical: tyrosine
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: amino acids; Chemical: arginine; Chemical: phenylalanine; Chemical: tryptophan; Chemical: tyrosine