title: Mass spectral characterization of C-glycosidic flavonoids isolated from a medicinal plant (Passiflora incarnata).
abstract: The four major C-glycosidic flavonoids isolated from Passiflora incarnata were identified as schaftoside, isoschaftoside, isovetexin-2''-O-glucopyranoside and isoorientin-2''-O-glucopyranoside on the basis of mass spectral and 13C NMR data. The daughter ion spectra of [M + H]+ ions of schaftoside and isoschaftoside showed differences for the [M + H - 104]+ ions, which could be rationalized by hydrogen bonding effects. In the negative-ion mode, pronounced differences were found for the [M - H - 90]- and [M - H - 120]- ions, formed by prevalent fragmentation in the C-6-linked sugar moiety. With respect to isovitexin-2''-O-beta-glucopyranoside and isoorientin-2''-O-beta-glucopyranoside, the daughter ion spectra of both the [M + H]+ and [M - H]- ions provided evidence for a 1----2 linkage in the diglucosidic moiety. Support for C-6 glucosylation was obtained by recording the daughter ion spectra of [M - H - 162]- ions, which were in good agreement with that obtained for [M - H]- ions of isovitexin.
authors.affiliation: Department of Pharmaceutical Sciences, University of Antwerp (U.I.A.), Wilrijk-Antwerp, Belgium.
authors.forename: Q M
authors.initials: QM
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: van den Heuvel
authors.forename: O
authors.initials: O
authors.lastname: Delorenzo
authors.forename: J
authors.initials: J
authors.lastname: Corthout
authors.forename: L A
authors.initials: LA
authors.lastname: Pieters
authors.forename: A J
authors.initials: AJ
authors.lastname: Vlietinck
authors.forename: M
authors.initials: M
authors.lastname: Claeys
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010946:Plants, Medicinal / Q000032:analysis*
chemical_list: D005419:Flavonoids