Catechin reaction between

FIa.VOnoIOxida.tlon, The fermentation process is initiated by the oxidation of catechins (1) to reactive catechin quinones (13), a process catalyzed by the enzyme polyphenol oxidase (PPO) (56). Whereas the gaHocatechins, epigaHocatechin, and epigaHocatechin gaHate, are preferred, polyphenol oxidase can use any catechin (Table 2) as a substrate. This reaction is energy-dependent and is the basis of the series of reactions between flavanoids that form the complex polyphenoHc constituents found in black and oolong teas. 

Pissarra, J. et al.. Reaction between malvidin 3-glucoside and (-t-)-catechin in model solutions containing different aldehydes, J. Food Sci., 68, 476, 2003. 

The oxygen-consuming reaction between a quinone derived from a simple catechin and a quinone derived from a gallocatechin results in the formation of a theafiavin. These compounds possess the benztropolone group that is based on a seven-membered ring. Figure 4 illustrates the formation of theaflavins. 

Fig. 2.102. Structures of all the compounds found in fraction A (a) anthocyanins (b) A-type vitisins (c) pyranoanthocyanins originated by reaction between anthocyanins and vynilphenol, vynilcatechol or vynilguaiacol (d) pyranoanthocyanins originated by reaction between anthocyanins and vynil(epi)catechin. Reprinted with permission from C. Alcalde-Eon et al. [236],...

Es-Safi, N.E. et ah. Structure of a new xanthylium salt derivative. Tetrahedron Lett. 40, 5869,1999. Es-Safi, N.E. et ah, 2D NMR analysis for unambiguous structural elucidation of phenolic compounds formed through reaction between (-l-)-catechin and glyoxylic acid. Magn. Reson. Chem. 40, 693, 2002. 

Es-Safi, N.E., Cheynier, V., and Moutounet, M., Study of the reactions between (+)-catechin and furfural derivatives in the presence or absence of anthocyanins and their implication in food color change. J. Agric. Food Chem. 48, 5946, 2000. 

Escribano-Bailon, M., Dangles, O., and Brouillard, R., Coupling reactions between flavylium ions and catechin. Phytochemistry 41, 1583, 1996. 

Es-Safi, N. E., Guerneve, C. L., Fulcrand, H., Cheynier, V, Moutounet, M. (1999b). New polyphenolic compounds with xanthylium skeletons formed through reaction between (-t)-catechin and glyoxylic acid. /. Agric. Food Chem., 47, 5211-5217. 

Other pigment families have been shown to occur in red wine, like anthocyanin oligomers (Salas et al. 2005 Vidal et al. 2004a), caftaric acid-anthocyanin adducts (Sarni-Manchado et al. 1997) or catechin-pyrylium derived pigments (i.e., oaklins) resulting from the reaction between catechin and wood aldehydes, like coniferalde-hyde or sinapaldehyde (de Ereitas et al. 2004 Sousa et al. 2005). These... 

Fig. 9D.10 Absorption spectra in the visible region of a catechin-pyrylium derived pigment derived from the reaction between catechin and sinapaldehyde as a function of pH...

Sousa, C., Mateus, N., Perez-Alonso, J., Santos-Buelga, C., de Ereitas, V. A P. (2005). Preliminary study of oaklins, a new class of brick-red catechin-pyryUran pigments resulting from the reaction between catechin and wood aldehydes. J. Agric. Food Chem., 53, 9249-9256. 

Peroxynitrite is a cytotoxic species generated by the reaction between superoxide and nitric oxide. Catechin polyphenols could also decrease the peroxynitrite-induced nitration of tyrosine and protect apolipoprotein B-lOO of LDL from peroxynihite-induced modification of critical amino acids, which contribute to its surface charge. ... 

These (+)-catechin polymers arise from repeated condensation reactions between the A ring of one unit and the B ring of another, through a mechanism which is known as head to tail polymerization (Scheme XXI). 

Escribano-Bailon T., Dangles O., Brouillard R. 1996. Coupling reaction between flavylium ions and catechin. PtQftochemistry. 41,1583-1592. 

Peroxynitrite (ONOO ) is a cytotoxic species generated by the reaction between snperoxide and nitric oxide (NO), which is a very strong oxidant and can cause oxidation of cell membrane protein and lead to cell damage and diseases. It can also generate hydroxyl radicals and NO2 nnder acidic conditions. Pannala et al." found that the scavenging effect of ECG and EGCG on ONOO was more pronounced than that of EC and EGC. Catechins were also found to protect from peroxynitrite-... 

Fig. 6.32. Reaction between catechin and malvidin-3-glucoside in an acid medium, in the presence of ethanal (Timberlake and Bridle, 1976)...

Wood extractives present in the timber are complex mixtures of chemicals such as tannins, anthocyanins, llavones, catechins, kinos, lignans and volatile hydrocarbons. Due to this diversity, countless opportunities exist for chemical reactions between extractives and the atmosphere, and between these materials and adhesives or other chemicals that may contact the materials at the wood surface. The pH and buffering capacity of the wood can be strongly affected by the type and amount of extractives. The setting or curing reactions of some adhesives have been reported to be sensitive to these factors [28]. Wood extractives are then extremely important because of their often undesirable and unpredictable effect on adhesive bonding. 

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