Structure elucidation of quercetin- and myricetin-O‐glycosides from the seeds of Trifolium repens

The phenolics present in different parts of Trifolium repens, mainly flowers and leaves and sometimes also roots, have been extensively studied, however, the data on the phenolic compounds occurring in the Trifolium repens seeds are very limited. Here, we report results of high pressure liquid chromatography-mass spectrometry (HPLC-MS) analysis of methanol extract of white clover seeds. Myricetin and quercetin, were detected as the main flavonoids, and for each of them three isomeric galactosides were detected. The structures of the myricetin and quercetin glycosides, including identification of glycosylation sites C-3, C-4′ and C-7, were elucidated on the basis of relative abundances of precursor ions and Y0+, Y0− and [Y0single bondH]−• product ions, and on the basis of quantum chemical calculations.