Structure characterization of flavonoid O‐diglycosides by positive and negative nano‐electrospray ionization ion trap mass spectrometry

Abstract

Isomeric flavonoid O-diglycosides were analyzed by positive and negative nano-electrospray ionization (ESI) ion trap mass spectrometry (ITMS) in order to evaluate whether the two most common interglycosidic linkage types, i.e. 1 --> 2 and 1 --> 6, found for glycosides containing a rhamnosylglucose glycan part can be differentiated. In the positive ion mode the degree of internal glucose residue loss was found to be strongly dependent on the aglycone type and was very pronounced for aglycones of the flavanone type. The relative abundance of the Y-type ions formed by fragmentation at glycosidic bonds only allows one to infer the interglycosidic linkage types in the case of flavone O-diglycosides. In contrast, the negative ion mode makes a clear differentiation between a rutinoside (1 --> 6) and a neohesperidoside (1 --> 2) glycan residue possible for all aglycone types. The neohesperidose-containing compounds could be characterized by additional product ions. When the compounds were dissolved in pure methanol a molecular radical ion was found to be the base peak in nano-ESI.

Hairy roots of Hypericum perforatum L.: a promising system for xanthone production

“…Five groups of phenolic compounds such as phenolic acids, flavonol glycosides, flavan-3-ols, flavonoid aglycones and xanthones were recorded in HR cultures (Table 1). Their identification was based on the typical UV/Vis spectral data and LC/MS in the negative ionization mode [M-H] -with the subsequent MS 2 , MS 3 and MS 4 analysis for further identification with reference to similar data previously reported [24][25][26][27][28][29][30][31][32][33]. The HPLC analysis of secondary metabolites revealed marked differences between control roots ( Figure 3A) and HR cultures ( Figure 3B).…”

“…In H. perforatum HR, the flavonol glycosides and flavonoid aglycones were observed to be qualitatively and quantitatively distinct from those of the corresponding control roots (Table 1, Figure 3 at m/z 609 and 593, and their MS 2 gave a single ion at m/z 301 and 285, respectively, indicating quercetin and kaempferol derivatives with rutinose at C3 [27]. The absence of intermediate fragmentation between the deprotonated molecular ion and the aglycone ion is indicative of an interglycosidic linkage 1→6 [28]; therefore these compounds were putatively identified as quercetin 3-O-rutinoside (rutin) and kaempferol 3-O-rutinoside. Three compounds (F9, F12, and F14) could be distinguished in HR cultures that belong to the group of flavonol glycosides.…”

“…-with loss of the characteristics of C-hexosyl compounds [28] and 327 as a base peak (1,3,6,7-tetrahydroxyxanthone-C-prenyl residue). Compounds X10 and X15 had UV spectra characteristic of 1,3,6,7-oxygenated xanthones and molecular ions [M-H] -at 327.…”

A study of isomeric diglycosyl flavonoids by SORI CID of fourier transform ion cyclotron mass spectrometry in negative ion mode

“…Structures of flavonoids have been correlated with their bioactivities [8,9], so it is crucial to provide authentic molecular structures via a time-saving method, e.g., mass spectrometry. Most of the previous papers have elucidated the structures of flavonoids based on lowresolution mass data, including the differentiation of flavonoid isomers [10,11] and multiglycosyl flavonoid structures [12,13]. Because most glycosyl flavonoids consist of C, H, O elements only, sometimes the analysis of the fragmentation pathways and the structures have been inconclusive based on low-resolution data, for example with an ion trap mass spectrometer [14].…”

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

“…The fragmentation pathways of flavonoid aglycons obtained by tandem mass spectrometry have been well-documented [13,22,23,27,50]. In addition, commonly encountered diglycosyl flavonoids can often be distinguished by their fragmentation path-ways [14,18,20,51,52]. For less common flavonoid glycosides, methods have recently been proposed for determining the saccharide identity [19], as well as the linkage order [14].…”