Quality evaluation of Hypericum japonicum by using high-performance liquid chromatography coupled with photodiode array detector and electrospray ionization tandem mass spectrometry.

A high-performance liquid chromatography coupled with photodiode array detection and electrospray ionization tandem mass spectrometry (HPLC-PAD-ESI-MS(n)) method was developed to evaluate the quality of Hypericum japonicum through establishing chromatographic fingerprint and simultaneous determination of seven phenolic compounds. The analysis was achieved on an Ultimate XB-C(18) analytical column (250 mm x 4.6 mm i.d., 5 microm) using an aqueous solution of acetic acid (pH 3.8) and methanol as the mobile phase. Ten samples of H. japonicum from various habitats were investigated and the correlation coefficients of similarity were determined from the HPLC fingerprints. By using an online ESI-MS(n), 20 common peaks in chromatographic fingerprints were identified as phenols, including flavones and their glycosides, flavonones and their glucosides, flavanols, xanthones, phloroglucinols, phenyl propanoids and chromones. Based on the above study, seven phenols which are considered to be major constituents in H. japonicum, including 3,4-dihydroxybenzoic acid (1), taxfolin-7-O-alpha-L-rhamnoside (7), 7-dihydroxy-2-(1-methylpropyl)chromone-8-beta-D-glucoside (8), isoquercitrin (14), quercitrin (16), quercetin-7-O-alpha-L-rhamnoside (18) and quercetin (19) were quantified by the validated HPLC-PAD method. This developed method by combination of chromatographic fingerprint and quantification analysis could be applied to control the quality of H. japonicum.