Trimeric proanthocyanidins

Balde, A.M. et al., Proanthocyanidins from stem bark of Pavetta owariensis. Part 2. Dimeric and trimeric proanthocyanidins possessing a doubly linked structure from Pavetta owariensis. Phytochemistry, 30, 4129, 1991. 

Balde, A.M. Pieters, L.A. Wray, V Kolodziej, H. Vanden Berghe, D.A. Claeys, M. Vlietinck, A.J. Dimeric and Trimeric Proanthocyanidins Possessing A Doubly Linked Structure from Pavetta owariensis. Phytochemistry, 1991, 30, 4129-4135. 

The bark composition includes the triterpenes p-amyrin, a not yet designated triterpenic acetate [78, 79] and a number of dimeric and trimeric proanthocyanidines (44) containing (+)-epicatechin and (+)-epigallocatechin units, with the 2S configuration which are rarely found in nature [80]. 

McMurrough I, Madigan D, Smyth MR (1996) Semipreparative chromatographic procedure for the isolation of dimeric and trimeric proanthocyanidins from barley. J Agric Food Chem 44 1731-1735... 

Flavan-3-ols are widely distributed in the Filicopsida and are almost invariably accompanied by condensed tannins. Several flavan-3-ol glycosides (389-394) have been isolated from ferns (202, 207, 240, 241). Dryopterin (280) found in Dryopterisfilix-mas is a new type of flavan-3-ol which contains an additional a-pyrone ring (181). Trimeric proanthocyanidins, arachnitannins 1 (282), 2 (283) and 3 (284), which contain dryopterin as the terminating unit were isolated from Arachniodes species (183). Proanthocyanidin polymers from Cyathea dealbata are composed of procyanidin and prodelphinidin in the ratio 6 4 (251). 

The A-type proanthocyanidins are characterized by a second ether linkage between an A-ring hydroxyl group of the lower unit and C-2 of the upper unit. Since they are less frequently isolated from plants than the B-types, they have been considered unusual structures [18,19]. The first identified A-type proanthocyanidin was procyanidin A2 isolated from the shells of fruit of Aes-culus hippocastanum. Since then, many more A-type proanthocyanidins have been found in plants, including dimers, trimers, tetramers, pentamers and ethers [18,21]. 

Although the above profusion of in vivo studies evidence their health potentialities, the problem of the bioavailabihty of proanthocyanidins supplied by dietary supplementation has still not been completely resolved since unequivocal evidence for absorption is missing so far [11]. However, studies carried out using radio-labelled procyanidins revealed that dimers and trimers may be absorbed by intestinal cells, whereas a recent study demonstrated that procyanidin oligomers are readily adsorbed in rats [55], while it has been shown that colon microflora may be able to degrade proanthocyanidins to low-molecular-weight aromatic compounds [56]. 

Balas, L., Vercauteren, J., and Laguerre, M., 2D NMR structure elucidation of proanthocyanidins the special case of the catechin-(4a-8)-catechin-(4a-8)-catechin trimer, Magn. Reson. Chem., 33, 85, 1995. 

Qa dan, F., Petereit, F., and Nahrstedt, A., Prodelphinidin trimers and characterization of a proanthocyanidin oligomer from Cistus albidus, Pharmazie, 58, 416, 2003. 

A-type proanthocyanidins are often incorrectly named due to the fact that the DEF moiety in, e.g., trimeric analogs, is rotated through 180°. The proposed system cognizant of this aspect will thus be used. Proanthocyanidin A-2 (8) is thus named epicatechin-(2(3 7, 4(3 8)-epicatechin. The proper name for the trimeric analog 9 is epicatechin-(2(3 7, 4(3 8)-epicatechin-(4(3 8)-epicatechin. 

Foo, L.Y. et al., A-type proanthocyanidin trimers from cranberry that inhibit adherence of uropathogenic P-fimbriated Escherichia coli, J. Nat. Prod, 63, 1225, 2000. 

Catechin and the proanthocyanidin prodelphinidin B3 are, respectively, the major monomeric and dimeric flavan-3-ols found in barley and malt where prodelphinidin B3 is the main contributor for the radical scavenging activity [Dvorakova et al., 2007], Proanthocyanidins have also been detected in nuts. Hazelnuts (Corylus avellana) and pecans (Carya illinoensis) are particularly rich in proanthocyanidins containing ca. 5 g kg, whereas almonds (Prunus dulcis) and pistachios (Pistachio vera) contain 1.8-2.4 mg kg 1, walnuts (Juglans spp.) ca. 0.67 g kg, roasted peanuts (Arachis hypgaea) 0.16 g kg, and cashews (Anarcardium occidentale) 0.09 g kg 1 [Crozier et al., 2006c]. Dark chocolate derived from the roasted seeds of cocoa (Theobroma cacao) is also a rich source of procyanidins [Gu et al., 2004], Monomeric flavan-3-ols and the proanthocyanidin B2, B5 dimers, and Q trimer are found in fresh cocoa beans (Fig. 1.13). Flavan-3-ols have also been detected in mint... 

Figure 1.13 Monomeric flavan-3-ols and proanthocyanidin B2, B5 dimers, and C, trimer found in fresh cocoa beans.

Polymeric color is a term that has been recognized in the wine industries for many years. Condensation of anthocyanins and proanthocyanidins may contribute to the formation of polymeric color, although the structural characterization of the compounds that contribute to polymeric color are poorly defined. Studies using electrospray mass spectrometric analysis demonstrated the presence of pigmented material from grape skins that was chiefiy composed of direct condensation products of anthocyanins extending up to trimers (Vidal et al., 2004). Recent studies have evaluated the effects of processing of blueberries. 

Procyanidin dimer, trimer, tetramer, and pentamers have molecular masses of 578, 866, 1154, and 1442, respectively. They can be easily identified using a mass spectrometer if [M H] m/z 577, 865, 1155, or 1441 are observed. Proanthocyanidins have three fragmentation... 

Proanthocyanidins with one A-type linkage have two less hydrogen than those of the B-type proanthocyanidins. A procyanidin trimer gave rise to [M-H] m/z 865, whereas a procyanidin trimer with one-type linkage yielded [M H] m/z 863. A-type interflavan bond differs from B-type bound in that they do not undergo QM cleavage. Thus,... 

MALDI-TOF-MS assay, purified proanthocyanidins in acetone were mixed with a matrix solution ( ra 5-3-indoleacrylic acid, 5 mg/100 pL in 80% aqueous acetone). The mixture (0.2 pL) was applied on a stainless steel target and dried at room temperature. Dried mixtures were subject to MALDI-TOF-MS using anN2 laser as the ionization and reflection mode for mass separation. Proanthocyanidins trimers to nonomers were detected (Krueger et ah, 2003). 

Deprez, S. Mila, I. Huneau, J.F. Tome, D. Scalbert, A. 2001. Transport of proanthocyanidin dimer, trimer, and polymer across monolayers of human intestinal epithelial Caco-2 cells. Antioxid. Redox. Signal 3 957-967. 

---