Epicatechin structure

Each of the four theaflavins theoretically are derived from the reactions the quinones of epicatechin or its gallate with those of epigallocatechin or its gallate has been identified in black tea and its structure authenticated.50... 

Fig. 3.1 Structures of (a) catechin, (b) epicatechin, (c) epicatechin gallate, (d) general structure of PAs, and (e) procyanidin dimer...

Natsume, M. et al., Structures of (—)-epicatechin glucuronide identified from plasma and urine after oral ingestion of (—)-epicatechin differences between human and rat. Free Radical Biol. Med., 34, 840, 2003. 

HPLC separation, as described above, is restricted to rather simple compounds that represent only a small proportion of flavonoids. Indeed, proanthocyanidin analysis becomes increasingly difficult as their molecular weight increases, due to the larger number of possible structures, smaller amounts of each individual compound, and poorer resolution of the chromatographic profiles. This is especially true of grape proanthocyanidins, which, unlike those of apple or cacao consisting only of epicatechin units, are based on four major... 

Cui, C-B. et al.. Constituents of a fern, Davallia mariessi Moore. IV. Isolation and structures of a novel norcarotane sesquiterpene glycoside, a chromone glucuronide, and two epicatechin glycosides, Chem. Pharm. Bull, 40, 2035, 1992. 

Bonnet, S.L. et al., Structure and synthesis of phlobatannins related to bis-fisetinidol-epicatechin profisetinidin trifiavanoids. Phytochemistry, 43, 253, 1996. 

Coetzee, J. et al., Oligomeric flavanoids. Part 31. Structure and synthesis of the first procassinidin dimers based on epicatechin, and gallo- and epigallocatechin. Phytochemistry, 53, 795, 2000. Hatano, T. et al., Flavan dimers with lipase inhibitory activity from Cassia nomame. Phytochemistry, 46, 893, 1997. 

Earlier proposals (12, 13, U) and the results of biosynthetic experiments (18) have been adumbrated into a scheme of biosynthesis for the procyanidins (Figure k) in which it is suggested that they are formed as byproducts during the final stage of the synthesis of the parent flavan-3-ol structures, (+)-catechin and (-)-epicatechin (11, 18). A two step reduction of the f1av-3-en-3-ol... 

Flavan-3-ols represent the most common flavonoid consumed in the American and, most probably, the Western diet and are regarded as functional ingredients in various beverages, whole and processed foods, herbal remedies, and supplements. Their presence in food affects quality parameters such as astringency, bitterness, sourness, sweetness, salivary viscosity, aroma, and color formation [Aron and Kennedy, 2007]. Flavan-3-ols are structurally the most complex subclass of flavonoids ranging from the simple monomers ( + )-catechin and its isomer (—)-epicatechin to the oligomeric and polymeric proanthocyanidins (Fig. 1.10), which are also known as condensed tannins [Crozier et al., 2006b]. 

Figure 2.1 Structure of flavan-3-ol monomers and dimers. (A)(—)-Epicatechin with = OH and R2 = H or ( + )-catechin with Ri = H and R2 = OH , (B) procyanidin (4p - 8)-dimer (C) procyanidin (4p -> 6)-dimer.

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