Flavan-3-ol glycosides

Hwang, B.Y. et al.. Antioxidant benzoylated flavan-3-ol glycoside from Celastrus orbiculatus, J. Nat. Prod, 64, 82, 2001. 

Flavan-3-ols are widely distributed in the Filicopsida and are almost invariably accompanied by condensed tannins. Several flavan-3-ol glycosides (389-394) have been isolated from ferns (202, 207, 240, 241). Dryopterin (280) found in Dryopterisfilix-mas is a new type of flavan-3-ol which contains an additional a-pyrone ring (181). Trimeric proanthocyanidins, arachnitannins 1 (282), 2 (283) and 3 (284), which contain dryopterin as the terminating unit were isolated from Arachniodes species (183). Proanthocyanidin polymers from Cyathea dealbata are composed of procyanidin and prodelphinidin in the ratio 6 4 (251). 

The effects of catechin, epicatechin, procyanidin B2, caffeic acid, / -coumaric acid, myricetrin, and quercetrin on the color intensity and stability of malvidin 3-glucoside at a molar ratio of 1 1 under conditions similar to red wine were evaluated. " Flavan 3-ols appeared to have the lowest protective effects and flavonols the highest strong color changes were visually perceptible. " In the complexation of malvin chloride and natural polyphenols, flavonol glycosides by far exerted the best protector effect. ... 

Calceolarioside A (phenylethanoid glycoside) Calceolarioside B (phenylethanoid glycoside) (+)-Catechin (= Catechinic acid Catechuic acid) (flavan-3-ol)... 

Monomeric units may be linked, to form oligomers and polymers, by C4-C6 and/or C4-C8 bonds (B-type) or doubly linked, with an addition C7-0-C2 ether linkage (A-type). Besides, flavan-3-ol units may be encountered as 3-0-esters, in particular with gallic acid, or as glycosides (25). Finally, the degree of polymerization (DP) may vary greatly as proanthocyanidins have been described up to 20,000 in molecular weight (26). 

Fig. 14 (-)-Epicatechin (flavan-3-ol, 62), (-)-epigallocatechin (flavan-3-ol, 63), (+)-catechin (flavan-3-ol, 43) and (+)-gallocatechin (flavan-3-ol, 64) in leaves of tea (Camellia sinensis L.), and analogs of luteolin (flavone, 65) and isoorientin C-glycoside (flavone C-glycoside, 66) in angiosperms...

A second class of defensive phytochemicals often found in poplar and aspen at substantial levels are the proanthocyanidins, or condensed tannins (CTs) (Fig. 5.1). Unlike the phenolic glycosides that are found exclusively in the Salicaceae, CTs are widespread in the plant kingdom. These flavonoid polymers consist of mostly 4,8-linked flavan-3,4-diols and flavan-3-ols, ranging in size from 1440 to over 4500 Da depending on the species. Flavonoids are derived from the general phenylpropanoid pathway by a series of enzymes beginning with the enzyme... 

Flavan-3-ols, often known as catechins (Fig. 11.16 of Chapter 11), are widely distributed. The most widely distributed members of this class of compounds are catechin [(+ )-(2/ ,35)-catechin] (2,3-trans) (3) and epicatechin [(-)-(2i ,3/ )-epicatechin] (2,3-cis) (30) (Fig. 12.1) which usually occur as free aglycones and not as glycosides. The known (2/ ,3S)-proanthocyanidins are tabulated by Porter (1988). The enantiomeric compounds are e f-catechin [(— )-(25,3/ )-catechin] 2,3-trans) and enf-epicatechin [( + )-(25,35)-epicatechin] (2,3-m). Some 2S-flavan-3-ols are found free and as gallate esters in plants (Stafford, 1989). Tissues that contain flavan-3-ols often contain procyanidin dimers and trimers (Haslam, 1975). Some flavan-3-ol com-... 

Complex tannins, also called flavano-ETs or flavono-ETs depending on the flavonoid unit, are hybrid tannins composed of a C-glycosidic ET and a glycosidically linked flavan-3-ol (like catechin or epicatechin), anthocyanin or procyanidin. ... 

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