2636
The water - soluble fraction , containing phenolic compounds , was extracted with ethyl acetate to obtain flavonoids which were separated and purified by repeated column chromatography over Sephadex LH - 20 , RP C18 and silica gel .
 ethyl acetate, flavonoids, silica gel
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 ethyl acetate, flavonoids, silica gel