Wine phenolics antioxidant properties

Revilla E and Ryan JM. 2000. Analysis of several phenolic compounds with potential antioxidant properties in grape extracts and wines by high-performance liquid chromatography—photodiode array detection without sample preparation. J Chromatogr 881(1-2) 461 169. 

This method is also used to measure ex vivo low-density lipoprotein (LDL) oxidation. LDL is isolated fresh from blood samples, oxidation is initiated by Cu(II) or AAPH, and peroxidation of the lipid components is followed at 234 nm for conjugated dienes (Prior and others 2005). In this specific case the procedure can be used to assess the interaction of certain antioxidant compounds, such as vitamin E, carotenoids, and retinyl stearate, exerting a protective effect on LDL (Esterbauer and others 1989). Hence, Viana and others (1996) studied the in vitro antioxidative effects of an extract rich in flavonoids. Similarly, Pearson and others (1999) assessed the ability of compounds in apple juices and extracts from fresh apple to protect LDL. Wang and Goodman (1999) examined the antioxidant properties of 26 common dietary phenolic agents in an ex vivo LDL oxidation model. Salleh and others (2002) screened 12 edible plant extracts rich in polyphenols for their potential to inhibit oxidation of LDL in vitro. Gongalves and others (2004) observed that phenolic extracts from cherry inhibited LDL oxidation in vitro in a dose-dependent manner. Yildirin and others (2007) demonstrated that grapes inhibited oxidation of human LDL at a level comparable to wine. Coinu and others (2007) studied the antioxidant properties of extracts obtained from artichoke leaves and outer bracts measured on human oxidized LDL. Milde and others (2007) showed that many phenolics, as well as carotenoids, enhance resistance to LDL oxidation. 

Vivas et al. 1997). Recently, the evaluation of the dual antioxidant and antibacterial activity of 21 phenolic compounds mainly present in Vitis Vinifera L. belonging to different groups was examined (Garcfa-Ruiz et al. 2008b). Structure-activity relationships were probed for both antimicrobial and antioxidant properties of wine phenolics, confirming the potential of these compounds as an alternative to sulphites in winemaking. 

Woraratphoka, J., K O. Intarapichet, K. Indrapichate. (2007). Phenolic compounds and antioxidative properties of selected wines from the northeast of Thailand. Food Chem. 104,1485-1490. 

Wine phenols are commonly referred to as polyphenols , due as may be seen in Figure 2, to the presence of multiple phenolic groups in their structures, which confer on these compounds various properties linked to health benefits, specifically the antioxidant properties attributed to the consumption of moderate amounts of red wine. Much has been published on this subject and the area and references to reviews may be found in Further reading section. 

Phenolic compounds, primarily flavonoids, have antioxidant properties which may contribute to health benefits of wine consumption (Kanner et ai, 1994 Frankel, 1994). Wine consumption has a possible cardioprotective effect and may prevent thrombosis (Frankel, 1994). Epicatechin and quercetin are more effective in preventing LDL (low density lipoprotein) oxidation than a-tocopherol (vitamin E) (Frankel, 1994). Quercetin is found at an average concentration of 25 mg/L in red wine. Catechin and epicatechins are among the most abundant phenolics in wine and are present at about 150 mg/ L in red wine and about 15 mg/ L in white wine. Resveratrol is thought to be of major importance as a dietary antioxidant in red wines, but levels are much lower than catechin/epicatechin (Frankel, 1994). 

Consumption of products rich in phenolic acids, such as wine and the Mediterranean diet, correlates with a reduced risk of cardiovascular disease. Since phenolic acids may exhibit antioxidant properties, a role in protecting low-density lipoprotein (LDL) from oxidative modification has been proposed [47, 99]. 

Phenolic substances in red wine were shown to inhibit LDL oxidation in vitro [95]. In previous studies, red wine-derived phenolic acids [115,116], resveratrol [117], flavonols (quercetin, myricetin) [68,118,119], catechins [66,120], and the grape extract itself [121,122] have been shown to possess antioxidant properties. The finding that ethanol and wine stripped of phenols did not affect LDL oxidation further confirmed that the active antioxidant components in red wine are phenolic compounds [123]. Red wine fractionation revealed major antioxidative potency to monomeric catechins, procyanidins, monomeric anthocyanidins, and phenolic acids [123]. The flavonol quercetin and the flavonol catechin were both tested for antioxidative and antiatherogenic effects in the atherosclerotic E° mice [111]. E° mice at the age of 4 weeks were supplemented for up to 6 weeks in their drinking water with placebo (1.1% alcohol) or with catechin or quercetin (50 pg/day/mouse). The atherosclerotic lesion area was smaller by 39% or by 46%, respectively, in the treated mice than in E° mice that were treated with placebo (Fig. 4A-E). 

Wine contains many phenolic substances. The phenolics have a number of important functions. In wine, especially in red wines, affect the tastes of bitterness and astringency. Second, the coior of red wine is caused by phenoiics. They are also bactericidal agents and impart antioxidant properties, being especially found in the skin and seeds of the grapes. 

Another very important category of glycosides is found in the grape hypoderm. These flavones, especially anthocyanins, are responsible for color in red grapes and wines (Section 6.2.3). Their heteroside nature is known to contribute to their stability. Like other phenols, (proanthocyanidins, tannins, etc.) (Section 6.2.4), they are considered to have antioxidant and antiseptic properties, as well as specific flavors. 

Phenolic compounds play a major role in enol-ogy. They are responsible for all the differences between red and white wines, especially the color and flavor of red wines. They have interesting, healthful properties, responsible for the French paradox . They have bactericide, antioxidant and vitamin properties that apparently protect consumers from cardiovascular disease. 

Many plant pigments are tricyclic phenols called flavanoids, which among their other properties are antioxidants. A flavanoid in green tea and red wine, (+)-catechin may play a role in the low incidence of atherosclerosis in Japan and France. 

Some of the most important chemicals naturally occurring in grapes and wines are phenolic compounds. The major quality properties of wines, such as flavor, color stability, and antioxidant capacity are strongly related to phenolic compounds. The study of Amarita et al. (2010) presented an alternative method for the rapid analysis of total phe-nolics in wines and juices based on an enzymatic FIA system. The design of the biosensor used the measurement of the oxygen consumed in the reaction catalyzed by the enzyme... 

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