Internal glucose residue loss in protonated O-diglycosyl flavonoids upon low-energy collision-induced dissociation

Abstract

The low-energy collision-induced dissociation of protonated flavonoid O-diglycosides, i.e., flavonoid O-rutinosides and O-neohesperidosides, containing different aglycone types has been studied. The results indicate that the unusual [M + H - 162]+ ion formed by internal glucose residue loss, which in a previous study was shown to be a rearrangement ion, is strongly dependent upon the aglycone type. For 7-O-diglycosides, the internal glucose loss is very pronounced for aglycones of the flavanone type, but is completely absent for aglycones of the flavone and flavonol types. Internal glucose residue loss was found to correspond to a minor fragmentation pathway for flavonol 3-O-diglycosides. A plausible mechanism is proposed based on proton mobilization from the aglycone to the disaccharidic part of the flavonoid O-diglycosides which is supported by theoretical calculations and model building.

Determination of the glycosylation site of flavonoid monoglucosides by metal complexation and tandem mass spectrometry

“…Several groups have reported characterization of flavonoids by electron ionization (EI) [6 -10] or fast atom bombardment (FAB) mass spectrometry [7,[11][12][13][14][15][16][17][18][19]. More recently, electrospray ionization (ESI) [19 -29], atmospheric pressure chemical ionization (APCI) [27][28][29][30][31], and matrix-assisted laser desorption ionization (MALDI) [32,33] have been used to analyze flavonoids, typically in conjunction with tandem mass spectrometry (MS/MS) or high-performance liquid chromatography (HPLC).…”

Establishment of mass spectrometric fingerprints of novel synthetic cholesteryl neoglycolipids: The presence of a unique C-glycoside species during electrospray ionization and during collision-induced dissociation tandem mass spectrometry

“…Claeys and collaborators evaluated the CID-MS/MS of O-flavonoid O-eutinosides and O-neohesperidosides, illustrating internal glucose residue loss. They proposed mobilization of the proton from the aglycone to the disaccharide portion [35]. Note that in the previous cases, these rearrangements reinstate the final formation of either O-ether or O-glycosidic linkages.…”

“…By comparison with the work of McLafferty, Brűll, and Claeys groups [28,29,[33][34][35], our work, presented in this rationale, includes a series of amphiphilic molecules containing an amino sugar and cholesteryl moieties separated by a polyethylene spacer, which are indeed quite different from the products used in their respective rearrangements. Also the formation of the final compounds is not an O-glycoside but a C-Glycoside, the formation of which represents a formidable synthetic task to be achieved in a MS instrument.…”

“…In addition, the cholesteryl cation that bears a positive charge, speculated to be localized on C-3=, was formed, possibly by intact COC covalent bond cleavage and was assigned as the [Cholestene] ϩ ion observed at m/z 369. 35.…”

“…This is followed by formation of the C-3=-C-4= double bond and migration of the endocyclic C-4=OC-5= double bond, to afford the protonated cholest-3,5-diene molecule assigned as [Cholesta-3,5-dieneϩH] ϩ at m/z 369. 35.…”