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Proanthocyanidin dimers

FIGURE 5.3 ESI-Q mass spectra obtained from two proanthocyanidin dimers. [Pg.269]

With reference to Table 11.1, butiniflavan (11) is named from three proanthocyanidin dimers based on 4-subtituted 25 -7,3, 4 -trihydroxyflavan (25 -flavans unsubstituted at C-3 possess the same orientation of substituents at C-2 as 2i -flavan-3-ols) isolated from Cassia... [Pg.554]

Figure 8.9 Fragmentation pathway of a proanthocyanidin dimer. The fragment mechanisms are RDA (retro-Diels-Alder), HRP (heterocyclic ring fission), and QM (quinone methide). Figure 8.9 Fragmentation pathway of a proanthocyanidin dimer. The fragment mechanisms are RDA (retro-Diels-Alder), HRP (heterocyclic ring fission), and QM (quinone methide).
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. [Pg.271]

Artz, W. E., Bishop, R D., Dunker, A. K., Schanus, E. G., Swanson, B. G. (1987). Interaction of synthetic proanthocyanidin dimer and trimer with bovine serum-albumin and purified bean globulin fraction G-1. J. Agric. Food Ghent., 35, 417-421. [Pg.560]

A theaflavin-related benzotropolone pigment having a procyanidin unit was synthesized in vitro. Although proanthocyanidin dimers have two B-rings, the condensation occurred regioselectively at the extension (upper) unit of the procyanidin due to steric effect. ... [Pg.62]

Foo, L.Y. A Novel Pyrogallol A-ring Proanthocyanidin Dimer from Acacia mela-noxylon. J. Chem. Soc., Chem. Commun., 236 (1986). [Pg.62]

Condensed tannins or proanthocyanidins are high-molecular-weight polymers. The monomeric unit is a flavan-3-ol (e.g., catechin and epicatechin), with a flavan-3,4-diol as its precursor (Figure 14.1). Oxidative condensation occurs between carbon C-4 in the heterocycle and carbons C-6 or C-8 of adjacent units [14]. However, most of the literature on the condensed tannin contents refers only to oligomeric proanthocyanidins (dimers, trimers, and tetramers) because of the difficulty of analyzing highly polymerized molecules. Proanthocyanidins, however, can occur as polymers with a degree of polymerization of 50 and more. [Pg.361]

Table 57.3 Distribution of proanthocyanidin dimers and trimers in food products... [Pg.1773]

Omar MH, Mullen W, Crazier A (2011) Identification of proanthocyanidin dimers and trimers, flavone c-glycosides, and antioxidants in Ficus deltoidea, a Malaysian herbal tea. J Agric Pood Chem 59 1363-1369... [Pg.2141]

Foo L Y 1986 A novel pyrogallol A-ring proanthocyanidin dimer from Acacia melanoxylon. J Chem Soc Chem Commun 236-237... [Pg.640]

The stereochemistry of proanthocyanidins is further complicated by atropiso-merism. Two such isomers occur for a proanthocyanidin dimer. For example in Figure 7.7.3, a dimer with an epicatechin-4 T unit will be 4)8 linked and adopt the two conformations 19 and 20, whereas a dimer with a catechin-4 T unit will be 4a linked and adopt the conformations 21 and 22. The atropisomers are manifested in H NMR spectra of dimers by many of the resonances occurring as doublets of unequal intensity (32, 38). The ratio of atropisomers may also be estimated from fluorescence decay experiments (12). [Pg.664]

Current evidence would lead one to modify this view somewhat. There are now examples of proanthocyanidin dimers and polymers known in which both the proanthocyanidin and flavan-3-ol unit are esterified. The evidence also supports the view that there may be an even closer link between hydrolyzable tannins and the gallate esters of tannins than suggested by Haslam. [Pg.680]

Hathway has shown that oak bark contains large concentrations of oxidase enzymes and demonstrated their effect on the flavan-3-ols which occur in oak bark (59). Ahn and Gstirner have reported the presence of oxidatively coupled flavan-3-ol dimers in oak bark, in addition to the normal proanthocyanidin dimers (2). Such products are consistent with the presence of oxidase/peroxidase enzymes. Such secondary processes would explain the very high dispersitivities observed for Firms sylvestris tannins, compared with values for tannins isolated from living plant tissue (R. Marutzky and L. J. Porter, unpublished observations). It would also account for the extremely high MW tannin-like material isolated by Yazaki and Hillis from Pinus radiata bark methanol extracts by ultrafiltration (145). [Pg.682]

De R, Kundu P, Swamakar S, Ramamurthy T, Chowdhury A, Nair GB, Mukhopadhyay AK(2009) Antimicrobial activity of curcumin against Helicobacter pylori isolates from India and during infections in mice. Antimicrob Agents Chemother 53 1592-1597 De Bruyne T, Pieters L, Witvrouw M, De Clercq E, Vanden Berghe D, VUetinck AJ (1999) Biological evaluation of proanthocyanidin dimers and related polyphenols. J Nat Prod 62 954-958... [Pg.27]


See other pages where Proanthocyanidin dimers is mentioned: [Pg.243]    [Pg.244]    [Pg.45]    [Pg.270]    [Pg.272]    [Pg.192]    [Pg.244]    [Pg.237]    [Pg.206]    [Pg.308]    [Pg.321]    [Pg.1766]    [Pg.420]    [Pg.255]    [Pg.279]   
See also in sourсe #XX -- [ Pg.14 ]

See also in sourсe #XX -- [ Pg.206 ]




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