Liquid chromatography electrospray ionization mass spectrometric characterization of flavonol glycosides in tomato extracts and human plasma

Flavonoids continue to attract wide attention as possible very useful agent s for combating free radical pathologies, i.e. the pathological states asso ciated with free radical overproduction, Commonly used methods for the anal ysis of plant flavonoids include high performance liquid chromatography (HP LC) and capillary electrophoresis (CE). On the other hand, the soft-ionizat ion approach based on electrospray ionization (ESI-MS) permits highly selec tive analysis of complex matrices. In this work, we examined firstly the ES I-MS behaviour of representative aglycones and glycosides of flavonols, fla vones and isoflavones with the aim of suggesting a possible relationship be tween structure and mass spectra. Using HPLC coupled to a diode array detec tor (DAD) for on-line UV spectra acquisition, and in parallel to ESI-MS for mass spectra (LC/DAD-ESI-MS), we have developed methodology to observe fla vonols directly in tomato puree extract, In this way, it has been possible to detect intact flavonol glycosides in tomato extracts and to characterize a flavonol trisaccharide. For the first time, using LC/ESI-MS, it has been possible to detect intact flavonol glycosides in plasma of healthy volunte ers and to provide further evidence on the absorption of flavonoid glycosid es after consumption of common vegetables like tomatoes. Copyright (C) 1999 John Wiley & Sons, Ltd.