Detection of isoflavonoids and their glycosides by liquid chromatography/electrospray ionization mass spectrometry in root extracts of lupin (Lupinus albus)

HPLC combined with electrospray ionization MS (LC–ESI-MS) was used for the identification of isoflavonoids and their glycosides in extracts from white lupin (Lupinus albus) tissues. The applicability of LC–ESI-MS for the simultaneous analysis of secondary metabolites of different polarities (free aglycones and their glycosides) is demonstrated. For optimization of the chromatographic and MS conditions, genistin (genistein 7-O-β-glucoside) and rutin [quercetin 3-O-β-(6″-O-α-rhamnosyl glucoside)] were used as standards. The detection limit for the analysis of genistin by HPLC was determined to be 20 ng (ca. 50 pmol). The analytical conditions established were employed to analyse isoflavonoids and their glycosidic conjugates obtained from lupin root extracts by solid phase extraction. Four glycosides and seven isoflavonoid aglycones were detected in the analysed samples. Copyright © 1999 John Wiley & Sons, Ltd.