Tandem mass spectrometry of the B‐type procyanidins in wine and B‐type dehydrodicatechins in an autoxidation mixture of (+)‐catechin and (−)‐epicatechin

Abstract

We describe the characterization of the B-type procyanidins in wine and the B-type dehydrodicatechins (dimeric flavan-3-ols) obtained for the autoxidation of (+)-catechin and (-)-epicatechin by tandem mass spectrometry (MS/MS) coupled to reversed-phase high-performance liquid chromatography (HPLC). The MS/MS analysis demonstrates that the interesting major fragments derive from the dissociations of the C-ring on the catechin or epicatechin unit, such as retro-Diels-Alder reactions. The two kinds of dimers give completely different fragmentations because of the striking effect of the C-C interflavan linkage (IFL). For the natural dimers in wine, a catechin or epicatechin unit linking to the C-4 position stabilizes the product ions by forming a large pi-pi hyperconjugated system, whereas a similar pi-pi system is formed within dehydrodicatechin B through the C-C IFL. Thus dissociation in MS/MS experiments was inhibited. Apparently, the fragmentations of the dimers differ from that of the monomer, which is very important in the study of the gas-phase ion behaviour of the polymeric flavan-3-ols. In addition, two specific fragment ions at m/z 451 for native dimers and at m/z 393 for autoxidation species in HPLC/MS/MS were found to be very useful for analysing mixtures of B-type procyanidins and B-type dehydrodicatechins in food and beverages.

Phenolic compounds of blackthorn (Prunus spinosa L.) and influence of in vitro digestion on their antioxidant capacity

“…Other polyphenol derivatives have been recently described. Dehydrodimers of flavan-3-ols can be formed from the oxidation of (+)-catechin and (−)-epicatechin (Sun & Miller, 2003). Correlation data obtained confirm that the new compounds named together as "undetected" derivatives formed during the process of intestinal digestion may contribute to the antioxidant activity of the sample digested.…”

“…In mass spectra, two groups of different masses corresponding to monomers and dimers of flavan-3-ol were detected ( Table 2). Much of the literature on flavan-ols by LC-MS has used negative electrospray (ESI) as the ionisation mode of choice as it has been reported to give improved sensitivity (Sun & Miller, 2003). However, more recently both negative and positive ESI have been utilised as the two dataset can often provide complementary information (Li & Deinzer, 2008).…”

Total phenolic, flavonoid and antioxidant activity of 23 edible flowers subjected to in vitro digestion

“…Some polyphenol derivatives have been described in other studies. Previous studies have found that dehydrodimers of flavan-3-ols can be formed from the oxidation of (+)-catechin and (−)-epicatechin (Sun & Miller, 2003). Some putative dimmers and phenolic compounds can be derived from anthocyanidins (Aura et al, 2005;Fleschhut, Kratzer, Rechkemmer, & Kulling, 2006), and protocatechuic acid can be formed by spontaneous degradation from cyanidin (Fleschhut et al, 2006).…”

HPLC–MS/MS profiling of proanthocyanidins in teas: A comparative study

“…For comparison purposes, a commercial grape seed extract has been analysed under the same conditions, as the PA composition of such extracts has been extensively examined by LC-MS (Gabetta et al, 2000;Monagas et al, 2006;Weber et al, 2006). Much of the literature on polyphenolics by LC-MS has utilised negative electrospray (ESI) as the ionisation mode of choice as it has been reported to give improved sensitivity (Sun and Miller, 2003). However, more Fig.…”