Determination of polyphenol components of Lonicera japonica Thunb. using liquid chromatography–tandem mass spectrometry: Contribution to the overall antioxidant activity

Three different mixtures of polyphenol components were isolated from the leaf, flower and stem of Lonicera japonica Thunb. via aqueous 70% methanol extraction followed by column chromatography over silica gel. The polyphenolic components of these mixtures were analysed via high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC–MS/MS) and compared with the reported data. Among the 25 characterized components, seven hydroxycinnamic acid derivatives and four flavonoid constituents were identified for the first time. The polyphenol compounds were validated and quantified on the basis of a representative polyphenol standard of the same group. The antioxidant activity of the polyphenol mixtures of the three tissues was determined. The antioxidant activity of the leaf was higher than that of the flower and stem.