Simultaneous separation and identification of oligomeric procyanidins and anthocyanin‐derived pigments in raw red wine by HPLC‐UV‐ESI‐MSⁿ

Abstract

Samples of raw red wine (Primitivo di Manduria, Apulia, Southern Italy) were analysed without any pre-treatment (except 1:2 dilution with water) using HPLC with detection based on UV absorbance and Electrospray Ionisation Sequential Mass Spectrometry (ESI-MSn, with n = 1-3) in a series configuration. In particular, absorbance at 520 nm was monitored for UV detection in order to identify pigments responsible for wine colour. On the other hand, two subsequent stages of MS detection based on positive ions were adopted. The first consisted of an explorative MS acquisition, aimed at the individuation of the m/z ratios for positively charged compounds; the second was based on fragmentation of the detected ions within an ion trap analyser, followed by MS/MS and, if required, MS3 acquisitions. The synergy between UV detection and MSn analysis led to the identification of 41 pigments, which can be classified into five groups: grape anthocyanins, pyranoanthocyanins, vinyl-linked anthocyanin-flavanol pigments, ethyl-bridged anthocyanin-flavanol pigments and flavanol-anthocyanin compounds. Many isomeric and oligomeric structures were found within each group. A further class of compounds, not absorbing in the visible spectrum, could be also characterised by ESI-MSn and corresponded to B-type procyanidins, i.e. proanthocyanidins arising from C4-->C8/C4-->C6 couplings between catechin or epicatechin units. In particular, oligomeric structures (from dimers to pentamers), often present with several isomers, were identified and their fragmentation patterns clarified.

Characterisation of genuine and derived cranberry proanthocyanidins by LC–ESI-MS

“…We observed the loss of a sugar moiety, the loss of monomer (D290 amu), A-type dimer (D576 amu) or B-type dimer (D578 amu) and the simultaneous loss of sugar and monomer or dimer. The same fragmentation pattern was observed by Pati et al (2006) for ethyl-bridged anthocyanin-(epi)catechin pigments in red wine. Reed et al (2005) reported in a similar study on a cranberry extract the detection of these 10 ions along with two additional ions at m/z 1023 (cyanidin-pentoside-ethyl-B-type dimer) and at m/z 1053 (cyanidin-hexoside-ethyl-B-type dimer).…”

Anthocyanin composition in aged Chilean Cabernet Sauvignon red wines

“…This molecular ion corresponds to the compound obtained in the cycloaddition of pyruvic acid to peonidin-3-O-glucoside known as vitisin A of peonidin-3-O-glucoside (Fulcrand et al, 1998). It has been previously reported in red wines (Alcalde-Eon et al, 2007;Atanasova et al, 2002;Pati et al, 2006). On the other hand, the reaction of malvidin-3-O-glucoside and acetaldehyde in wine model solution showed, by ESI/MS analysis after 48 h, the formation of a malvidin-3-O-glucoside dimer mediated by acetaldehyde, with a molecular ion at m/z 1012.…”

“…Also acetyl, coumaryl and caffeyl-glucosides were detected. Pati et al (2006) reported the formation in young red wine of condensation products of malvidin-3-O-glucoside with catechin and epicatechin mediated by ethyl or vinyl bridges. The resolution of the chromatograms over 50 min is low, which indicates that compounds with molecular weights between m/z 900 and 1500 are co-eluting (Fig.…”

“…Free anthocyanins and polymeric anthocyanins were detected and identified by mass spectrometric methods. Fast atom bombardment mass spectrometry (FAB-MS), matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS), and electrospray (ESI) mass spectrometry have been used (Bakker & Timberlake, 1997;Giusti, Rodríguez-Sanoa, Griffin, & Wrolstad, 1999;Pati et al, 2006;Piovan, Filippini, & Favretto, 1998;Wang & Sporns, 1999).…”

The Evolution of Polyphenols from Grapes to Wines

“…Quantification by ESI/MS of anthocyanins present in grape extract can be done by constructing a calibration curve using two commercially available standard compounds, the Mv-3-O-glucoside (M+ species at m/z 493) for monoglucosides and the Mv-3,5-O-diglucoside (M+ species at m/z 655) for diglucosides [44].…”