Simultaneous analysis of flavonoids from Hypericum japonicum Thunb.ex Murray (Hypericaceae) by HPLC-DAD-ESI/MS.

A novel and sensitive HPLC-UV method has been developed for the simultaneous determination of five major flavonoids in Hypericum japonicum hydroalcoholic extract. The chemical profile of five flavonoids, including taxfolin-7-O-alpha-L-rhamnoside (1), isoquercitrin (2), quercitrin (3), quercetin-7-O-alpha-L-rhamnoside (4) and quercetin (5) was acquired by using high-performance liquid chromatography-diode array detector coupled to an electrospray tandem mass spectrometer (HPLC-DAD-ESI/MS). The analysis was performed on a ZORBAX SB-C18 analytical column (5 microm, 250 mm x 4.6 mm, i.d.) with a gradient solvent system of acetonitrile-0.5% aqueous formic acid. The validation was carried out and the linearities (r(2)>0.9997) and recoveries (ranged from 98.4% to 99.8%) were acceptable. The limits of detection (LOD) of these flavonoids ranged from 0.5 to 7.5 ng. The results indicated that the contents of investigated flavonoids in H. japonicum varied significantly from habitat to habitat with contents ranging from 2.00 to 34.18 mg/g. The proposed method is simple, effective and suitable for the quality control of this traditional Chinese medicine (TCM).