Procyanidins in grapes

Reversed-phase HPLC is used for the analysis of the different groups of phenols, phenolic acids, hydroxycinnamic acids, flavonoids, and procyanidins in grapes and wines (22,46,47,77-80). However, due to the presence of a large quantities of various compounds, wine analysis is difficult. Thus, different sample preparation procedures, including fractionation and extraction, are often applied when various groups of phenolic compounds are studied together. 

De Freitas, V.A.P., Glories, Y. and Monique, A. (2000) Developmental changes of procyanidins in grape of red Vitis vinifera varieties and their composition in respective wines. Am. J. Enol. Vitic., 51(4), 397-403. 

The use of calibration factors is an attempt to correct for differences in molar absorbances. This approach has been chosen for the quantitation of procyanidins in grape tissue using (+)-catechin [194,270] and in red wine using procyanidin B2 (and B2-3 -0-gallate) [244]. The disadvantage of such quantitation procedures is, that the experimental (i.e. chromatographic) conditions must be kept unchanged, which sometimes is difficult to accomplish. 

Oligomers and procyanidins in grape skins are similar to those in seeds [87] the latter, however, have a higher mDp (30 units in some varieties [78,85]). (—)-Epicatechin prevails in the extension units, and catechin in terminal units [78]. Prodelphinidins, also present in skin [67,88], contain epigallocatechin as their main constituent unit, in addition to epigallocatechin-3-O-gallate and gallocatechin, the latter as a terminal unit. 

Ricardo DS, Darmon N, Eemandez Y et al (1991) Oxygen free radical scavenger capacity in aqueous models of different procyanidins from grape seeds. 1 Agric Pood Chem 39 1549-1552... 

As discussed above, the development of mild MS techniques has led to further progress in the determination of proanthocyanidin size distribution. In particular, ESI-MS studies have demonstrated that prodelphinidin and procyanidin units coexist within the polymers, where they seem distributed at random. A list of mass signals attributed to proanthocyanidins detected in grape or wine extracts is given in Table 5.2. 

Cheynier, V. and Ricardo Da Silva, J.M., Oxidation of grape procyanidins in model solutions containing tra 5-caffeoyl tartaric acid and grape polyphenoloxidase. J. Agric. Food Chem. 39, 1047, 1991. 

A dual-electrode liquid chromatography-electrochemistry (LCEC) system used in the detection and identification of flavanols and procyanidins in wines and grape seeds is a valuable tool (30). Voltammetric behavior of phenolic compounds by LCEC could provide information that cannot be obtained using HPLC with UV detection, for which the identification is usually based on a comparison of the retention time with that of standard compounds, especially for the identification of catechins and procyanidins with a small amount of sample available (30). Figure 10 shows the procyanidins commonly found in wines. 

Aldini G, Carini M, Piccoli A, Rossoni G Facino RM. 2003. Procyanidins from grape seeds protect endothelial cells from peroxynitrite damage and enhance endothelium-dependent relaxation in human artery New evidences for cardio-protection. Life Sci 73 2883-2898. 

Figure 16.4 Influence of ionic strength on the aggregates formation between BSA (6.1 x 10 mM) and oligomeric procyanidins from grape seed (O.lOmM) (in 12% aqueous ethanol, 0.1 M acetate buffer, pH 5.0) [78].

Figure 8.6 Chromatograms of grape seed procyanidins. Excitation and emission wavelength were 230 nm and 321 nm using fluorescence detector. (A) was run on a 250 X 4.6 mm phenomenex Luna silica column using gradient in Table 8.1. (B) was run on a Develosil Diol 100 A column (250 x 4.6 mm, 5 pm particle size) using gradient in Table 8.3. Same sample and injection volume (10 pL) was used. Numbers above the peaks denote the DP values of procyanidins in the peaks.

Vivas de Gaulejac, N., Vivas, N., Absalon, C., Nonier, M. F. (2001). Identification of procyanidin A2 in grape and wine of Vitis vinifera L. cv Merlot Noir and Carbemet-Sauvignon. J. Int. Sci. Vigne Vin, 35, 51-56. 

Several proanthocyanidin classes can be distinguished on the basis of the hydroxylation pattern of the constitutive units. Among them, procyanidins, consisting of (epi)catechin units (3, 4 di OH), and prodelphinidins, deriving from (epi)gallocatechin (3 ,4, 5 tri OH), Figure 2, have been reported in grapes. 

Anthocyanins are intensely coloured plant pigments, consisting of glycosylated anthocyanidins. MS analysis of phenols, procyanidins, and anthocyanins in grapes and wines was reviewed by Flamini [79]. Some studies on the LC-MS analysis of anthocyanidins are briefly reviewed here. 

FIGURE 3.3 Structures of (a) flavonols, (b) flavan-3-ols and (c) the dimeric procyanidin Bl, occurring in grapes and berry fruits. [Source Adapted from Spanos and Wrolstad (1992).]... 

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