Polyphenols polymerized

FIGURE 2.18 Possible mechanisms of polyphenol polymerization or activation leading to haze development based on concepts from Gardner and McGuinness (1977). 

Kammerer ei aL1(n m have conducted extensive studies on the template polymerization of acrylate or methacrylate derivatives of polyphenolic oligomers 22 with X n < 5 (Scheme 8.14). Under conditions of low "monomer" and high initiator concentration they found that X n for the daughter polymer was the same as X n for the parent. The possibility of using such templates to control microstructure was considered but not reported. 

In the wine industry, FTIR has become a useful technique for rapid analysis of industrial-grade glycerol adulteration, polymeric mannose, organic acids, and varietal authenticity. Urbano Cuadrado et al. (2005) studied the applicability of spectroscopic techniques in the near- and mid-infrared frequencies to determine multiple wine parameters alcoholic degree, volumic mass, total acidity, total polyphenol index, glycerol, and total sulfur dioxide in a much more efficient approach than standard and reference methods in terms of time, reagent, and operation errors. 

Kantz, K. and Singleton, V.L., Isolation and determination of polymeric polyphenols in wines nsing Sephadex LH-20, Am. J. Enol. Viticult., 42, 309, 1991. 

Laccase is one of the main oxidizing enzymes responsible for polyphenol degradation. It is a copper-containing polyphenoloxidase (p-diphenoloxidase, EC 1.10.3.2) that catalyzes the oxidation of several compounds such as polyphenols, methoxy-substituted phenols, diamines, and other compounds, but that does not oxidize tyrosine (Thurston, 1994). In a classical laccase reaction, a phenol undergoes a one-electron oxidation to form a free radical. In this typical reaction the active oxygen species can be transformed in a second oxidation step into a quinone that, as the free radical product, can undergo polymerization. 

Wine and beer industry Polyphenols can alter color and flavor of products such as wines. There are many aggressive ways of removing polyphenolic compounds, such as using polyvinylpolypyrrolidone (PVPP) or sulfur dioxide. However, polyphenol removal should be selective to avoid the undesirable alteration of the wine s organoleptic characteristics. For this reason, one option is to use laccases that polymerize the polyphenolic compounds during the wine-making process and then to remove these polymers by clarification (Morozova and others 2007). Several papers have reported that laccase is able to remove undesirable polyphenols and produce stable wines with a good flavor. 

It is interesting to underline that there is another (plant) enzyme which possesses a coordinatively similar dicopper environment catechol oxidase.11 As already mentioned in Chapter 6, Section 3, such an ubiquitous enzyme catalyses the two-electron oxidation by molecular dioxygen of catechols to the corresponding quinones (the so-generated quinones in turn polymerize to form brown polyphenolic catechol melanins, which protect damaged plants from pathogens or insects). 

In studies on hamsters and guinea pigs exposed to aerosols of crude and refined extracts from cotton mill trash and CMD, Kilburn et al (59) has further demonstrated recruitment of PMN beneath the basement membrane and on luminal surfaces of intrapulmonary airways and tracheas. When administered as aerosols or dust, polyphenolic extracts from cotton trash and pure and oxidization-polymerization products of quercetin also recruit PMN from the trachea to terminal bronchioles in hamsters (60). 

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. 

Polyphenols constitute one of the most and widely distributed groups of substances in the plant kingdom, with more than 8000 phenolic structures currently known. They can be divided into at least 10 different classes based upon their chemical structure, ranging from simple molecules, such as phenolic acids, to highly polymerized compounds, such as tannins. 

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