Electrospray ionisation mass spectrometric study of degradation products of quercetin, quercetin-3-glucoside and quercetin-3-rhamnoglucoside, produced by in vitro fermentation with human faecal flora

Eight phenolic compounds, obtained by in vitro fermentation of quercetin, q uercetin-3-glucoside and quercetin-3-rhamnoglucoside were analysed by elect rospray ionisation mass spectrometry (ESI-MS). Low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS) was performed on the [M - H](-) precursor ions to obtain specific fragmentation. Typical fragmentat ion of the phenolic acids was loss of 44 (CO2) and 18 (H2O) u. Production o f m/z 108 by loss of neutral radicals, e.g. HCO2, CH3 or HCO, was also favo ured. Structures of the compounds, numbered 1-8, were suggested based on th e fragmentation patterns. Copyright (C) 2001 John Wiley & Sons, Ltd.