6997
The 5 , 7 - OH group of A ring and one 4 ' - OH group of the B ring in apigenin and naringenin are important for synergistic activity .
 Chemical: 5 , 7 - OH; Chemical: 4 ' - OH; Chemical: apigenin; Chemical: naringenin
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: 5 , 7 - OH; Chemical: 4 ' - OH; Chemical: apigenin; Chemical: naringenin