Flavanols chemical structure

Flavonoids are divided into many classes and subclasses, each with a slightly different chemical structure and function. Classes of flavonoids include flavanols, flavanones, catechins, anthocyanins, and isoflavones. 

Figure 4.2 Chemical structures of various flavonoidsThe flavone heterocyclic ring can be reduced or oxidized in various ways. Reduction of the double bond leads to a flavanone. Additional loss of the carbonyl oxygen yields a flavan.Jhe flavone can be hydroxylated to form a flavonol. This can be reduced to a flavanol. The flavan, flavanol, and flavanone each have a chiral center. The biological isomers are not known.

Figure 6.1 Chemical structures of flavanoids including catechins and theaflavins. These tiavanoids consisted of two major groups flavanones, including naringenin, taxifolin, and fustin, and flavanols including green tea polyphenols (EC, ECG, EGC, EGCG), black tea polyphenols (TF-1, TF-2a, TF-2b, TF-3), and oolong tea polyphenol (TSA).

Figure 1. Chemical structures of flavanols and a cocoa (-)-epicatechin dimer. Higher molecular weight procyanidins typically oligomerize through the 4 -8 bond.

Overexpression of P-glycoprotein associated with multidrug resistance represents a serious problem in cancer treatment. Evaluation of catechins, fla-vonoids, isoflavonoids, and anthocyanins effects on multidrug-resistant human epidermal carcinoma cells has demonstrated that catechins and antho-cyanidins are most effective inhibitors of P-gp overexpression. It was observed that hydrophobicity enhances planar flavonoids inhibitory effects without affecting nonplanar flavanols activity that significantly depended on their chemical structure [119]. 

Fig. 72.1 Chemical structure of principal flavanol monomers of grapes and wine...

Fig. 18.4. Chemical structures of flavonoids Flavanols (Faol), Anthocyanidines (Acn), Flavanones (Faon), Flavones (Fon), Flavonols (Fool), Isoflavones (Ifon, cf. 16.2.9). R H, OH or OCH3...

Salas E, Poncet-Legrand C, Fulcrand H, Meudec E, Cheynier V (2004) Structure and properties of a flavanol-anthocyanin adduct. In 228th National meeting of the American-Chemical-Society, Philadelphia, 22-26 Aug 2004. American-Chemical-Society, Philadelphia, pp 112-CELL... 

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