Dear Dr Laouini,

As you know there are more than 5000 flavonoids have been identified in fruits, vegetables and herbs.  Probably you look for the top five flavonoids for human heath. I am attaching our method that we developed in QUB-UK. Also I will attache other methods for isolation from literature.

Good luck

For phenolic flavanoids, extraction with methanol, followed by ion exchange (strong anion exchange), followed by LH-20 or polyamide, finally C18 works well.

http://www.isco.com/WebProductFiles/Applications/101/Poster_and_Paper_Reprints/Purification_of_Phenolic_Flavonoids.pdf

http://www.isco.com/WebProductFiles/Applications/101/Application_Notes/AN87_RediSep%20Rf_SAX_Column_Applications.pdf