Hi. I suggest you read our new article entitled: " Chronic Administration of Rosa Canina Hydro-alcoholic Extract Attenuates Depressive-like Behavior and Recognition Memory Impairment in Diabetic Mice: A Possible Role of Oxidative Stress" In this article we completely explained the extraction method of flavonoid reach plant Rosa canina.
Flavonoids easily get degraded by enzymatic action so I suggest use dried, lyophilized or frozen sample for extraction. This paper might come in handy Article Extraction, isolation and identification of flavonoid from E...
Flavonoids exists in the form of glycosides in the plant. They are highly polar. Hence , to extract the flavoniod rich fraction from plants it is better to use ethanol or methanol, by soaking the plant material in the solvent & keeping for 3-4 days & concentrating under rotatory evaporation. The residual thick liquid is rich in flavonoid which can be chromatographed using Methanol + Chloroform mix.(9:1)proportion.