1510
Target repurposing , achieved by the matching of essential parasite enzymes to those human enzymes that have been successfully inhibited by small molecule drugs , provides an attractive means by which new drug optimization programs can be pragmatically initiated .
 None
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:  
Answer:
 None