Nonflavonoids phenolic acids

Several classes of compounds with antioxidant activity have been identified in oats (Avena sativa L.), including vitamin E tocols, flavonoids, and nonflavonoid phenolic acids (see Handelman et... 

Nonflavonoid compounds comprise simple phenols, phenolic acids, coumarins, xanthones, stilbenes, lignins, and lignans. Phenolic acids are further divided into benzoic acid derivatives, based on a C6-C1 skeleton and cinnamic acid derivatives, which are based on a C6-C3 skeleton [6], The conmarins are phenolic acid derivatives composed of a benzene ring fnsed with an oxygen heterocycle. Xanthones consist of a C6-C1-C6 basic structure, and stilbenes are composed of a C6-C2-C6 skeleton with various hydroxylation patterns [13], Lignins are polymers of C6-C3 units, whereas lignans are made up of two phenylpropane units [13]. The structures of each of these classes are shown in Table 16.1. 

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... 

These compounds are a kind of nonflavonoid phenolics characterized by the C6-C3 structure. Hydroxycinnamic acids are abundant in... 

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). 

Phenols include several hundred compounds that are broadly grouped as flavonoids and nonflavonoids. The former include anthocyanins, cate-chins, and tannins the latter include stilbenes and other compounds derived from benzoic, caffeic, and cinnamic acids. 

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