Procyanidin C2

Moreover, monomers and dimers were shown to repress NO production, TNF alpha secretion, and NF-kB-dependent gene expression induced by interferon y, whereas the trimeric procyanidin C2 and Pycnogenol enhanced these parameters. In addition, in unstimulated RAW 264.7 macrophages, both procyanidin C2 and Pycnogenol increased TNF gamma secretion in a concentration and time-dependent manner. These results demonstrate that procyanidins act as modulators of the immune response in macrophages [105]. 

Another membrane property physically affected by flavonoids is the surface potential. Working with liposomes composed of PC and PS, we found that (—)-epicatechin and certain procyanidins (dimer to hexamer) decreased liposome surface potential. This effect relied on both, procyanidin concentration and number of monomeric units [Verstraeten et al., 2003]. On the other hand, when liposomes were composed exclusively of PC, it was found that (—)-epi-catechin dimers Al and B2, and the trimers A and C2 increased liposome surface potential in a concentration-dependent manner [Verstraeten et al.,... 

The structural diversity of procyanidins is based on the two possible monomer units (+)-catechin and (-)-epicatechin, on the different types of interflavanoid bonds and on the different lengths of chains which are possible. Besides the most common C4—>C8 and C4—>C6 linkages doubly linked flavan-3-ol structures exist, too. In addition to a C4- C8 bond they are linked by an ether bond between 07—>C2 [1] (see Fig. (3)). Cyclic structures have been proposed for procyanidins from kaki (Diospyros kaki) [12] and cherry (Primus avium) [13]. Higher molecular weight procyanidins are usually of moderate size (up to 3 000 daltons) [14], but also polymers with very high molecular weights (20 000 to ISO OOO... 

The crucial question for the final chromatographic analysis is, which procyanidins are to be expected in a given matrix. Naturally occurring procyanidins predominantly consist of either (-)-epicatechin or (+)-catechin. In the (-)-epicatechin series procyanidins B2, B5, Cl and an (-)-epicatechin tetramer co-occur (i.e. in Crataegus sp.), while principal components in the (-t-)-catechin series are procyanidins B3, B6, C2 and a (+)-catechin tetramer (i.e. in Salix sp.). Predominance of procyanidins B1 (i.e. in Rubus sp.) or B4 (i.e. in Sorghum sp.) is relatively seldom in the plant kingdom. The main procyanidins are always accompanied by the... 

Type-A procyanidins (C30H24O12) (Figure 6.16) are dimers that, in addition to the C4-C8 or C4-C6 interfiavan bond, also have an ether bond between the C5 or C7 carbons of the terminal unit and the C2 carbon of the upper unit. Procyanidin A2 has been identified in wine (Vivas and Glories, 1996). Form B can change to form A via a radical process. 

It was reported that esterification of (—)-epicatechin and procyanidin B2 by gallic acid can occur and that these gallate esters are only found in the grape seed extract. Grape seed extract contains oligomer procyanidins made up of dimers or trimers of (+)-catechin and (—)-epicatechin.4-6 The procyanidin dimers are comprised of procyanidins Bl, B2, B3, B4, B5, B6, B7, and B8. There are six procyanidin trimers which include procyanidins Cl and C2. 

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