An investigation of the homolytic saccharide cleavage of deprotonated flavonol 3‐O‐glycosides in a quadrupole ion trap mass spectrometer

Abstract

The trend in the extent of homolytic saccharide cleavage is reported for a series of deprotonated flavonol 3-O-glycosides upon collision-induced dissociation (CID) in a quadrupole ion trap mass spectrometer. The second-generation product ions from the primary [Y(0)](-) and [Y(0)- H](-.) product ions were also identified. It was determined that the structure of both the aglycon and the saccharide portions of the flavonoid glycoside are pivotal in inducing radical cleavage. In contrast to earlier work on this subject reported for a smaller group of flavonols, the correlation between the degree of B-ring hydroxylation and the extent of radical saccharide cleavage showed several notable exceptions in the present work. Homolytic cleavage was also investigated in the context of using tandem mass spectrometry to identify the aglycon portions of flavonoid glycosides.

Low energy induced homolytic fragmentation of flavonol 3‐O‐glycosides by negative electrospray ionization tandem mass spectrometry

“…They also proposed that increased hydroxylation degree of ring B could enhance the homolytic fragmentation . Since then, this characteristic radical cleavage has been extensively applied to structural characterization of flavonoid O ‐glycosides . Recently, Ablajan proposed that [Y 0 –2H] – and [Y 3 0 –H] –• were diagnostic for the characterization of flavonols with 3‐ and 7‐ O ‐glycosyl substitutions .…”

Studies on the homolytic and heterolytic cleavage of kaempferol and kaempferide glycosides using electrospray ionization tandem mass spectrometry

“…18 Thereafter, there was growing interest in studies of the radical aglycone ions in CID experiments of the deprotonated flavonoid glycosides. [19][20][21][22][23] Compared with flavonol 7-O-glycosides, flavonol 3-O-glycosides have been reported to yield homolytic cleavage fragments in large amounts. Even the relative abundance ratio of [Y 0 -H] À. to [Y 0 ] À has been proposed as a diagnostic criterion to determine the glycosylation position of flavonol glycosides.…”

Separation and identification of phenolic compounds in Bidens pilosa L. by ultra high performance liquid chromatography with quadrupole time‐of‐flight mass spectrometry

“…Increasing the CID energy above 30 eV led to the loss of a hydrogen free radical from the fragment ion at m/z 301, which produced the fragment ion at m/z 300 as base peak. The fragment ions at m/z 271, 255 that generated from the ion at m/z 300 by loss of 29 [CO+H·] amu and 45 [CO+OH·] amu were the diagnostic ions for 3‐O‐substituted quercetin . The similar fragment pathway was observed for compound 4 .…”

“…Loss of 132 amu from the parent ion at m/z 433 [M–H] – of compound 7 showed a pentose linked to an aglycone. Similar to compounds 3 and 4 , compound 7 also produced the fragment ions at m/z 300, 271, 255, 151 at 30 eV that indicated the presence of 3‐O‐substituted quercetin . Thus, compound 7 was identified as quercetin‐3‐ O ‐pentose.…”

“…The (ESI–)‐MS/MS fragmentation pattern of compound 11 ([M–H] – at m/z 625 with molecular formula C 30 H 26 O 15 ) revealed the presence of a quercetin aglycone, and the glycosylation was on the hydroxyl at the 3‐position . Besides, The UV maximum absorbance of compound 11 at 332 nm was characteristic to hydroxycinnamic acid .…”