Polyphenolic compounds oxidation

Sample pre-treatment. Novel procedures of electrochemical sample treatment have been proposed to decrease the signal interference with native cholinesterase inhibitors present in fruits and vegetables. Polyphenolic compounds were removed by electrolysis with soluble A1 anode followed by the oxidation of thionic pesticides with electrogenerated chlorine. The procedure proposed makes it possible to decrease the background current and the matrix effect by 80-90%. Thus, the detection limits of about 5 ppb of Pai athion-Methyl and Chloropyrifos-Methyl were obtained in spiked grape juice without any additional sepai ation or pre-concentration stages. 

Polyphenolic compounds are present in mate. Flavanols, at least in significant quantities, are absent.9 The major phenolic compounds are chlorogenic acid and its oxidation products referred to as resinotanol , which are formed during the manufacturing process.10 The chlorogenic acid may be a mixture of three different isomers.11... 

In the present study, we have focused our attention on the catalytic wet peroxide oxidation of p-coumaric acid over (Al-Fe)PILC. This phenolic molecule was chosen as a representative of the biologically recalcitrant polyphenolic compounds present in olive oil processing and wine distillery wastewaters. 

Vitamins (C and E), polyphenolic compounds, and carotenoids are the main groups of antioxidants present in fruits and vegetables. Vitamins are single molecules, but polyphenols and carotenoids are made up of hundreds of compounds with a wide range of structures and molecular masses. The intake of these antioxidants can lead to sustained reduction of the kind of oxidative damage to lipids, proteins, and DNA that is associated with the development of chronic diseases (Evans and Halliwell 2001). 

Wildenradt, H. L. and Singleton, V. L. (1974). Production of aldehydes as a result of oxidation of polyphenolic compounds and its relation to wine aging. Am.. Enol. Viticult. 25, 119-126. 

Although many polyphenolic compounds can quench DPPH215 218 and scavenge radicals in competition with spin traps,225 232,278 consideration must also be given to the fate of the resultant phenoxyl radicals, which can include their direct reaction with important biomolecules, further oxidation to cytotoxic quinones and, in the case of semiquinones, their reduction of oxygen to superoxide. Thus,... 

Fig. (4). Vasodilatory mechanisms of flavonoids. RWPC red wine polyphenolic compounds NO nitric made NOSe nitric oxide synthase endothelial O2 superoxide anions OONO peroxynitrites PKC protein kinase Q AC adenylate cyclase GC guanylate cyclase PDE phosphodiesterase.

Wallerath T, Li H, Godtel-Ambrust U, Schwarz PM, Forstermann U. 2005. A blend of polyphenolic compounds explains the stimulatory effect of red wine on human endothelial NO synthase. Nitric Oxide 12 97-104. 

Biocatalytic membrane readors are also used for the treatment of musts and wines by the conversion of polyphenolic compounds and anthocyanes. Laccase is used to oxidize polyphenols in solution and anthodanase is used immobilized on synthetic and natural polymers to hydrolyze anthocyanes. 

The infusion of spices and herbs not only gives vermouth its unique flavor and aroma but also imparts medicinal properties. Some of the benefits ascribed to vermouth are given in Table 8.1. Feher and Lugasi (2004) compared the antioxidant characteristics of young vermouth with three red, three white, and one rose wine. Consumption of one unit (100 mL) of vermouth provided 220 mg polyphenolics, whereas wine in the same quantity was reported to have 35 mg. Polyphenolic compounds are reported to play a substantial role in protection against oxidative stress. 

Vaccinium myrtillus, commonly known as bilberry fruit, originates mainly from northern and central Europe (Bisset, 1994). This well known plant is rich in flavonoids, the polyphenolic compounds that promote anti-oxidant activity (Bisset, 1994). A study conducted on the antioxidative potential of V. myrtillus showed potent protective action on LDL particles during in vitro copper-mediated oxidation. The study concluded that this extract may be more potent than either ascorbic acid or butylated hydroxy-toluene in the protection of LDL particles from oxidative stress (Mitcheva, 1993 Bisset, 1994). 

Thiaminolytic enzymes are found in a variety of microorganisms and foods, and a number of thermostable compounds present in foods (especially polyphenols) cause oxidative cleavage of thiamin, as does sulfite, which is widely used in food processing. The products of thiamin cleavage by sulfite and thiaminases are shown in Figure 6.1. 

Among polyphenolic compounds, two types of flavonoids, the anthocyanins and flavanols (i.e., catechins, proanthocyanidins, condensed tannins), are particularly relevant to the quality of red wines, as they are key compounds for color definition and astringency. Other flavonoids such as flavonols may have some influence on color and bitterness, although they are present in red wines in much lower amounts. Phenolic acids and hydrolysable tannins, released from barrel wood, may also have an influence on wine taste and color, and hydroxycinnamoyl derivatives from grape must are involved in the oxidative browning of white wines together with flavanols. Besides, some of these perceptions may be modified by other sensory characteristics (e.g. sourness, sweetness) related to other wine components (Preys et al. 2006). 

Wildenradt, H. L., Singleton V. L. (1974). Production of aldehydes as a result of oxidation of polyphenolic compounds and its relation to wine aging. J. Agric. Food Chem., 25, 119-126. Wroblewski, K., Muhandiram, R., Chakrabartty, A., Bennick, A. (2001). The molecular interaction of human salivary histatins with polyphenolic compounds. Eur. J. Biochem., 268, 4384-4397. 

Deckert, V, Desrumaux, C., Athias, A., Duverneuil, L., Palleau, V, Gambert, R, Masson, D., Lagrost, L. (2002). Prevention of LDL alpha-tocopherol consumption, cholesterol oxidation, and vascular endothelium dysfunction by polyphenolic compounds from red wine. Atherosclerosis, 165, 41-50. 

Sunflower meal contains the polyphenolic compound, chlorogenic acid, which results in a yellow-green coloration following oxidation in the presence of alkah. The production of protein isolates and concentrates from sunflower meal/flour would require the removal or inactivation of chlorogenic acid (35, 37). 

The use of natural antioxidants in supplements can also exhibit pro-oxidant activity under certain conditions such as the concentration and nature of the polyphenolic compounds causing oxidative damage to important cellular components (48). Aqueous extracts and erode polyphenolic fractions of both traditional and green rooibos were evaluated for possible pro-oxidant activity using a Fenton reaction model system containing FeCb-EDTA and H2O2 for the generation of hydroxyl radicals. Pro-oxidant activity was shown for pure aspalathin while the dihydrochalcone and flavonoid contents of the enriched... 

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