21721
The pyridyl pi - pi 2 * transition may be contained within the negative ECD signal envelope at around 200 nm .
 Chemical: pyridyl
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: pyridyl 
Answer:
 Chemical: pyridyl