Epicatechins gallates

The total antioxidant activity of teas and tea polyphenols in aqueous phase oxidation reactions has been deterrnined using an assay based on oxidation of 2,2 -azinobis-(3-ethylbenzothiazoline-sulfonate) (ABTS) by peroxyl radicals (114—117). Black and green tea extracts (2500 ppm) were found to be 8—12 times more effective antioxidants than a 1-mAf solution of the water-soluble form of vitamin E, Trolox. The most potent antioxidants of the tea flavonoids were found to be epicatechin gallate and epigallocatechin gallate. A 1-mAf solution of these flavanols were found respectively to be 4.9 and 4.8 times more potent than a 1-mAf solution of Trolox in scavenging an ABT radical cation. 

TERAO J, PiSKULA M and YAO Q (1994) Protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation in phospholipid bilayers , Arch Biochem Biophys, 308, 278-84. 

Figure 5.3. Flavanol monomers (catechins, epicatechins, and their gallates) and pro-cyanidins. C catechin GC, gallocatechin EC, epicatechin EGC, epigallocatechin CG, catechin gallate GCG, gallocatechin gallate ECG, epicatechin gallate, EGCG, epigallocatechin gallate.

The effects of flavonoids on in vitro and in vivo lipid peroxidation have been thoroughly studied [123]. Torel et al. [124] found that the inhibitory effects of flavonoids on autoxidation of linoleic acid increased in the order fustin < catechin < quercetin < rutin = luteolin < kaempferol < morin. Robak and Gryglewski [109] determined /50 values for the inhibition of ascorbate-stimulated lipid peroxidation of boiled rat liver microsomes. All the flavonoids studied were very effective inhibitors of lipid peroxidation in model system, with I50 values changing from 1.4 pmol l-1 for myricetin to 71.9 pmol I 1 for rutin. However, as seen below, these /50 values differed significantly from those determined in other in vitro systems. Terao et al. [125] described the protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation of phospholipid bilayers. 

Fig. 2.62. HPLC chromatogram of (a) jasmin (green) tea, (b) Fujian Oolong tea, (c) pu-erh tea and (d) black tea at 280 nm. Peak identification 1 = gallic acid (GA) 2 = (-)-epigallocatechin (EGC) 3 = (-)-epigallocatechin gallate (EGCG) 4 = epicatechin (EC) 5 = (-)-epicatechin gallate (ECG) 6 = caffeine (CA) 7 = ( — )-catechin gallate (CG). Reprinted with permission from Y. Zuo et al. [178].

Fig. 2.64. Representative chromatogram of tea infusions. Conditions C18 column acetonitrile-aqueous acetate buffer gradient absorbance at 210 nm. Peak identities 1 = epigallocatechin (EGC) 2 = caffeine 3 = epicatechin (EC) 4 = epigallocatechin gallate EGCG) 5 = epicatechin gallate (ECG) 6 = internal standard (naringenin). Reprinted with permission from W. E. Bronner et al. [180].

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

Figure 3. Epicatechin-gallate, a possible tur-inducer from grapes.

C, catechin EC, epicatechin EGC, epigallocatechin ECG, epicatechin gallate EGCG, epigallocatechin gallate GC, gallocatechin. 

Rosa acicularis Lindl. China Vitamins, gallocatechin, epigallocatechin, epicatechin gallate, catechin, epicatchin, fatty acids.48 Stop vomitting blood, stomachache, relieve pain caused by nervous system, menstruation. 

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