Polyphenols nonflavonoids

There are numerous other polyphenolic compounds possessing in vitro and in vivo antioxidative activity. Several examples of these compounds are cited below. One of nonflavonoid polyphenols of particular interest is resveratrol (3,5,4 -trihydroxy-Znmv-stilbcne, Figure 29.8), which has been identified as a potential cancer chemopreventive agent and an antimutagen [182]. It has been found that resveratrol is the efficient inhibitor of cyclooxygenase and the inhibitor of free radical-mediated cellular processes. For example, resveratrol is a better free radical scavenger than a-tocopherol or ascorbic acid but has nearly the same activity as... 

FIGURE 4.2 Wine oxidation processes adapted from Danilewicz (2003) R = further organic groups such as the three-ring structure in the flavonoids, and further groups in nonflavonoid polyphenols. 

Phenohc acids are nonflavonoid polyphenolic compounds that mainly exist in two forms based on C1-C6 and C3-C6 backbones, benzoic and cinnamic acid derivatives, coimnonly known as hydroxycinnam-ic and hydroxybenzoic acids. Hydroxybenzoic acids (Figure 3.9) are found in a few plants consumed by humans, such as berries and onions [54], While vegetables and fhiits contain many free phenolic acids, in seeds and grains, particularly in the bran or hull, phenolic acids are... 

Polyphenols can be classified according to their chemical structure into two important groups flavonoids and nonflavonoid compounds (Figure 21.1). 

The nonflavonoid polyphenols include the phenolic acids or hydroxybenzoates (basic chemical structure C6-C1), hydroxycinammates (basic chemical structure C6-C3), and polyphenolic stilbenes (basic chemical structure C6-C2-C6). 

Vineyard and wine production residues differ in polyphenolic composition among one another. Thus, even grape pomace (or grape marc) is rather heterogenous as it consists of skins (50%), seeds (25%), and stems (25%). In any case, polyphenols in these residues are of either the flavonoid or nonflavonoid type. 

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