13342
Interestingly , docking of the two active molecules 3k and 3w into the active site of COX - 2 indicates that these compounds are COX - 2 ligands with strong hydrophobic and hydrogen bonding interactions .
 Chemical: hydrogen
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: hydrogen