Extraction and hydrolysis parameters for determination of quercetin in Hypericum perforatum

The optimum conditions for extraction of rutin and quercetin from Hypericum perforatum were investigated. The best efficiency of extraction was achieved with aqueous methanol 40-80% (v/v). For quercetin analysis as aglycone the effect of acid concentration and hydrolysis time on the extraction recovery were also studied. Hydrolysis for 5 min in the presence of 2.8 mol L-1 HCl as well as for 10 min with 1.1 mol L-1 HCl efficiently released quercetin from rutin. The content of quercetin-3-O-glycosides (rutin, hyperoside and quercetrin) and quercetin aglycone as well as chlorogenic and caffeic acids in H. perforatum leaves and flowers were determined by HPLC with photodiode-array detection and confirmed by electrospray mass spectrometry.