Evaluation of glycosylation and malonylation patterns in flavonoid glycosides during LC/MS/MS metabolite profiling

Abstract

Flavonoid conjugates constitute several classes of plant phenolic secondary metabolites including many isomeric compounds differing in the hydroxylation pattern and substitution of their rings with different groups such as alkyls, acyls or sugars. These compounds occur in plant tissues mainly as glycosides and in many cases it is necessary to have reliable and detailed information concerning the structure of these natural products. Our results were obtained using leaf extracts of Arabidopsis thaliana and Lupinus angustifolius in which different glycosides of flavones, flavonols and isoflavones are present. Analysis of collision-induced dissociation (CID)/MS/MS spectra of protonated [M + H](+), sodiated [M + Na](+) or deprotonated [M - H](-) molecules recorded during HPLC runs may bring needed information in this respect. However, registration of mass spectra of [M + Na](+) ions with a good efficiency is possible only after post-column addition of a sodium acetate solution to the LC column eluate. The retention of sodium cation on the saccharidic parts of the molecule is observed after the CID fragmentation. In many cases, the location of this cation on the glycan attached to C-3 hydroxyl group of flavonol led to assignment of its structure. Additionally, the determination of the structure of the aglycone and of the sequence of the glycan part was made possible through the CID data obtained from the [M + H](+) and [M - H](-) ions. CID spectra show a different order of sugar elimination from hydroxyl groups at C-3 and C-7 in flavonol glycosides isolated from A. thaliana leaves and give sufficient information to discriminate flavonoid O-diglycosides from flavonoid di-O-glycosides.

Chemical composition of hydroethanolic extracts from Siparuna guianensis, medicinal plant used as anxiolytics in Amazon region

“…Compound 10, peak at 26.0 min (Table 2) (Table 2) can be rationalized by loss of an internal glucose residue (Shahat et al, 2005;Kachlicki et al, 2008). Compound 10 was tentatively characterized as quercetin-3-O-rutinoside-7-O-rhamnoside.…”

“…The different types of CID spectra were evaluated with respect to their structural information content, such as, their utility to locate the O-linked saccharide residues and to determine the sequence in the disaccharidic part. The glycan cleavage sequence in [M+H] + ions of flavonol O-glycosides started with the elimination of glycoside residue from C-3 carbon atom of flavonol (Shahat et al, 2005;Kachlicki et al, 2008). Ions of deprotonated molecules [M-H] -are usually more stable than their protonated counterparts, so higher collision energy is necessary for the fragmentation of the precursor ions.…”

“…Ions of deprotonated molecules [M-H] -are usually more stable than their protonated counterparts, so higher collision energy is necessary for the fragmentation of the precursor ions. Generally, the most abundant product ions obtained from deprotonated molecules were formed after loss of glycoside residue attached to the C-7 carbon atom of flavonol (Shahat et al, 2005;Kachlicki et al, 2008). Thus, generally, the 3-O and 7-O glycosides in flavonol 3,7-di-O-glycosides can readily be located on the basis of ESI-MS/MS, while the loss of 3-O glycoside is more abundant than that the 7-O glycoside for protonated molecules, the opposite behavior is observed for deprotonated and sodiated molecules (Shahat et al, 2005;Kachlicki et al, 2008).…”

“…Generally, the most abundant product ions obtained from deprotonated molecules were formed after loss of glycoside residue attached to the C-7 carbon atom of flavonol (Shahat et al, 2005;Kachlicki et al, 2008). Thus, generally, the 3-O and 7-O glycosides in flavonol 3,7-di-O-glycosides can readily be located on the basis of ESI-MS/MS, while the loss of 3-O glycoside is more abundant than that the 7-O glycoside for protonated molecules, the opposite behavior is observed for deprotonated and sodiated molecules (Shahat et al, 2005;Kachlicki et al, 2008). 1 R 1 =sophoroside; R 3 =OH; R 2 =R 4 =R 5 =H 2 R 1 =R 2 =glucosyl; R 3 =R 4 =R 5 =H 3 R 1 =arabinosyl; R 2 =glucosyl; R 3 =R 4 =R 5 =H 4 R 1 =glucosyl; R 2 =arabinosyl; R 3 =R 4 =R 5 =H 5 R 1 =R 4 =R 5 =H; R 2 =glucosyl; R 3 =OH 6 R 1 =sophoroside; R 2 =R 3 =R 4 =R 5 =H 7 R 1 =R 3 =R 4 =R 5 =H; R 2 =glucosyl 9 R 1 =R 2 =glucosyl; R 3 =OH; R 4 =R 5 =H 10 R 1 =R 2 =H; R 3 =OH; R 4 =rutinoside; R 5 =rhamnosyl 11 R 1 =R 2 =H; R 3 =OH; R 4 =pentosyl-pentoside; R 5 =rhamnosyl 12 R 1 =R 2 =H; R 3 =OH; R 4 =R 5 =rhamnosyl 13 R 1 =R 2 =R 3 =H; R 4 =pentosyl-pentoside; R 5 =rhamnosyl 14 R 1 =R 2 =R 3 =H; R 4 =R 5 =rhamnosyl 15 R 1 =R 2 =H; R 3 =OH; R 4 =pentosyl-rhamnoside; R 5 =rhamnosyl that compounds 10, 11 and 13 (Table 2) first lost a rhamnose (C 6 O 4 H 10 ) moiety [M-H-146]-, given the fragments at m/z 609.0 (compound 10), 565.0 (compound 11) and 549.0 (compound 13) (see Table 2) indicating the presence of 7-O-rhamnosyl group linked to hydroxyl group of aglycone (Shahat et al, 2005;Kachlicki et al, 2008).…”

Chemical composition of hydroethanolic extracts from five species of the Passiflora genus

“…The MS/MS spectrum of protonated molecule at m/z 741.1, showed a fragment at m/z 579.1, corresponding to the loss of hexose, Generally, the 3-O and 7-Oglycosides in flavonoids 3,7-di-O-glycosides can readily be located on the basis of ESI-MS/MS. While the loss of 3-O-glycoside is more abundant than that the 7-O-glycoside for protonated molecules; the opposite behavior is observed for deprotonated and sodiated molecules (Kachlicki et al, 2008). The fragment at m/z 579.1, corresponds to the loss of hexose of protonated molecule.…”