Procyanidins oxidation

Some flavonoids, such as procyanidins, have antidiabetic properties because they improve altered glucose and oxidative metabolisms of diabetic states (Pinent and others 2004). Extract of grape seed procyanidins (PE) administered orally to streptozotocin-induced diabetic rats resulted in an antihyperglycemic effect, which was significantly increased if PE administration was accompanied by a low insulin dose (Pinent and others 2004). The antihyperglycemic effect of PE may be partially due to the insuli-nomimetic activity of procyanidins on insulin-sensitive cell lines. 

Arteel and Sies (1999) examined procyanidin oligomers of different size, isolated from the seeds of Theobroma cacao, for their ability to protect against nitration of tyrosine. Serraino and others (2003) investigated antioxidant activity of the blackberry juice and cyanidin-3-O-glucoside on endothelial dysfunction in cells and in vascular rings exposed to peroxynitrite. However, more work is needed in this area, and the confounding effects of oxidized protein/amino acids in the diet need to be elucidated. 

Lu Y, Zhou WZ, Chang Z, Chen W-X and Li L. 2004. Procyanidins from grape seeds protect against phorbol ester-induced oxidative cellular and genotoxic damage. Acta Pharmacol Sin 25(8) 1083-1089. 

Cheynier, V. and Ricardo Da Silva, J.M., Oxidation of grape procyanidins in model solutions containing tra 5-caffeoyl tartaric acid and grape polyphenoloxidase. J. Agric. Food Chem. 39, 1047, 1991. 

Simonetti, P., Ciappellano, S., Gardana, C., Bramati, L., and Pietta, P., Procyanidins from Vitis vinifera seeds in vivo effects on oxidative stress, J. Agric. Food Chem., 50, 6217, 2002. 

Kozikowski, A.P., Tuckmantel, W., and George, C., Studies in polyphenol chemistry and bioactivity. 2. Establishment of interflavan linkage regio- and stereochemistry by oxidative degradation of an 0-alkylated derivative of procyanidins B2 to (R)-(—)-2,4-diphenylbutyric acid, J. Org. Chem., 65, 5371, 2000. 

Kondo, K. et al.. Conversion of procyanidin B-t5 pe (catechin dimer) to A-type evidence for abstraction of C-2 hydrogen in catechin during radical oxidation, Tetrahedron Lett., 41,485, 2000. 

A 12-fold increase in plasma epicatechin concentration from 22 to 257 nmol/L was reported by Rein et al [105] after consumption of 80 g semisweet (procyanidin rich) chocolate within 2 h after ingestion. The total antioxidant capacity of plasma increases of 31% within the same time, and plasma 2-thiobarbituric acid reactive substances decreased up to 40%. These data support that consumption of chocolate increases plasma epicatechin concentrations and decreases plasma baseline oxidation products. These results have been confirmed in another study by Wang et al [106]. 

Erlejman AG, Jaggers G, Fraga CG, Oteiza PI. 2008. TNFa-induced NF-kB activation and cell oxidant production are modulated by hexameric procyanidins in Caco-2 cells. Arch Biochem Biophys 476 186-195. 

Verstraeten SV, Keen CL, Schmitz HH, Fraga CG, Oteiza PI. 2003. Flavan-3-ols and procyanidins protect liposomes against lipid oxidation and disruption of the bilayer structure. Free Radic Biol Med 34 84-92. 

The finding that water-soluble flavonoids could exert their beneficial properties at the hydrophobic portion of the membrane was also observed in in vivo studies and in cells in culture. For example, erythrocytes obtained from animals fed a flavanol- and procyanidin-rich meal showed reduced susceptibility to free-radical-mediated hemolysis [Zhu et al., 2002]. Consistently, we demonstrated that procyanidin hexamers, which interact with membranes but would not be internalized, protected Caco-2 cells from AMVN- and bile-induced oxidation [Erlejman et al., 2006]. When liposomes were preincubated with a series of flavonoids with diverse hydrophobicity, not only hydrophobic flavonoids prevented AMVN-mediated lipid oxidation but also the more hydrophilic ones [Erlejman et al., 2004]. Similarly to what was previously found in liposomes, the protective effects of flavonoids against AMVN-supported oxidation was strongly associated with their capacity to prevent membrane disruption by detergents, supporting the hypothesis of a physical protection of membranes by preventing oxidants to reach fatty acids. 

Erlejman AG, Fraga CG, Oteiza PI. 2006. Procyanidins protect Caco-2 cells from bile acid- and oxidant-induced damage. Free Radic Biol Med 41 1247-1256. 

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