Polymeric procyanidins

Lea AGH. 1978. The phenolics of ciders oligomeric and polymeric procyanidins. J Sci Food Agric... 

Polymeric procyanidin extraction from black beans (Phaseolus vulgaris L. cv. Black Turtle Soup) and purification was a... 

Prieur C, Rigaud J, Cheynier V et al (1994) Oligomeric and polymeric procyanidins from grape seeds. Phytochemistry 36 781-784... 

Guyot S, Doco T, Souquet JM et al (1997) Characterization of highly polymerized procyanidins in cider apple skin and pulp. Phytochemistry 44 351-357... 

Takahata Y, Ohnishi-Kameyama M, Furuta S et al (2001) Highly polymerized procyanidins in brown soybean seed coat with a high radical-scavenging activity. J Agric Food Chem 49 5843-5847... 

Kusuda M, Inada K, Ogawa TO, Yoshida T, Shiota T, Shiota S, Tsuchiya T, Hatano T. (2006) Polyphenolic constituents structures of Zanthoxylum piper-itum fruit and the antibacterial effects of its polymeric procyanidin on methicillin-resistant Staphylococcus aureus. Biosci Biotechnol Biochem 70 1423-1431. 

Nonhydrolyzable or condensed tannins are also named proanthocyanidins. These are polymers of flavan-3-ols, with the flavan bonds most commonly between C4 and C8 or C6 (Figure 6-23) (Macheix et al. 1990). Many plants contain tannins that are polymers of (+)-catechin or (-)-epicatechin. These are hydrogenated forms of flavonoids or anthocyanidins. Other monomers occupying places in condensed fruit tannins have trihydroxylation in the B-ring (+)-gallocat-echin and (-)-epigallocatechin. Oligomeric and polymeric procyanidins are formed by addition of more flavan-3-ol units and result in the formation of helical structures. These structures can form bonds with proteins. 

The last decade has seen quite remarkable advances in our knowledge of the structure and properties of the proanthocyanidins. Viscosity measurements were made of solutions of procyanidins isolated from Theobroma cacao and Chaenomeles speciosa with number-average degrees of polymerization of 6.1 and 11.8, respectively, in water and 1% sodium hydroxide at 25 °C. Procyanidins are apparently completely crosslinked by formaldehyde up to a chain length of 6 units, but few units are crosslinked in polymeric procyanidins. The second order rate constants observed for the formaldehyde reaction with catechin or epicatechin are approximately six times higher than that observed for the C. speciosa polymer. 

These results may be compared with viscosities obtained in a similar way from conifer bark extracts which, while heterogeneous, contain polymeric pro-cyanidins or mixed polymeric procyanidins and prodelphinidins as their predominant components (2). For example, Weissman (25) reported a viscosity of 65 mPa-s for a 30% solution of the water extract from Pinus oocarpa bark, and Dix and Marutsky (26) obtained a value of 31 mPa-s for a similar solution from Picea abies bark. These viscosities are similar to those observed for the 30% procyanidin polymer solutions. They indicate that the viscosities of these bark extract solutions are dominated by the proanthocyanidins and that there is little influence from any accompanying polysaccharides-as already suggested by Weissmann (25)-in contrast to wattle extracts where gums play an important role in determining solution viscosities (7). 

If polymeric procyanidins extractable from conifer tree barks are to be used in adhesive formulations requiring condensation with phenol-formaldehyde prepolymers, these reactions must be performed at acidic pH conditions, and because of solubility limitations, this will probably require the use of sulfonate derivatives. 

GuL. KelmM. Hammerstone J.F. Beecher G. Cunningham D. Vannozzi S. Prior R. L. 2002. Fractionation of polymeric procyanidins from lowhush blueberry and quantification of procyanidins in selected foods with an optimized normal-phase HPLC-MS fluorescent detection method. J. Agric. Food Chem. 50 4852-4860. 

Svedstrom, U. Vuorela, H. Kostiainen, R. Laakso, L Hiltunen, R. 2006. Fractionation of polyphenols in hawthorn into polymeric procyanidins, phenolic acid, and flavonoids prior to high-performance liquid chromatographic analysis. J. Chromatogr. A. 1112 103-111. 

Procyanidin monomers through decamers can be separated on normal-phase HPLC according to the degree of polymerization. Procyanidin polymers with DP >10 elute as a single peak after decamers. No other HPLC method is known to achieve similar or better results. Two types of normal-phase columns may be chosen to separate proanthocyanidins. One option is to use unmodified silica as a stationary phase. Good separation of proanthocyanidins was achieved on a 250 x 4.6 mm silica column (Luna, 5 pm particle size, part number 00F-4274-E0,... 

Gu, L. Kelm, M. Hammerstone, J.F. Beecher, G. Cunningham, D. Vannozzi, S. Prior, R.L. 2002. Fractionation of polymeric procyanidins from lowbush blueberry... 

Countercurrent chromatography (CCC) is a liquid-liquid partition technique that eliminates various complications arising from the use of solid supports. The highspeed CCC, the most advanced form in terms of partition efficiency and separation time, has been used for the separation and purification of a wide variety of natural products. The recent model of high-speed CCC, which facilitates the stationary phase retention for polar solvent systems, is particularly useful for the separation of hydrophilic, highly polymerized procyanidins. 

Table IV shows the evolution of monomeric, oligomeric and polymeric procyanidins, measured at the end of the wood aging period and after one year in the bottle. Some increases in monomeric procyanidins were detected during oak aging, perhaps as a result of the breakdown of oligomeric procyanidins or the extraction of monomeric compounds from the wood.

Table IV. Evolution of monomeric (MP), oligomeric (OP) and polymeric procyanidins (PP) during oak and bottle aging (mg/L)...

Prieur, C. Rigaud, J. Cheynier, V. Moutounet, M. Oligomeric and polymeric procyanidins from grape seeds Vitis vinifera). Phytochemistry 1994, 36, 781-784. 

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