Catechin epigallocatechin-gallate

Tamba Y, Ohba S, Kubota M, Yoshioka H, Yamazaki M. 2007. Single GUV method reveals interaction of tea catechin (—)-epigallocatechin gallate with lipid membranes. Biophys J 92 3178-3194. 

Fukuyo, M., Hara, Y., and Muramatsu, K. 1986. Effect of tea leaf catechin, (—)-epigallocatechin gallate, on plasma cholesterol level in rats. Nippon Eiyo. Shokuryo. Gakkaishi 39, 495-500 (in Japanese). 

LONG L H, CLEMENT M V and HALLiwELL B (2000) Artifacts in cell-culture rapid generation of hydrogen peroxide on addition of (-)-epigaUocatechin, (-)-epigallocatechin gallate, (-i-)-catechin, and quercetin , Biochem Biophys Res Commun, 273 (1), 50-53. 

The catechins are soluble in water, colorless, and possess an astringent taste. They are easily oxidized and form complexes with many other substances including the methylxanthines.44 Epigallocatechin gallate is the... 

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.

Fig. 1. Amperometric monitoring of the autoxidation of epigallocatechin gallete in the presence of (A) 0, (B) 2.0, (C) 5.0, (D) 10, (E) 20, and (F) 50 pm CuCl2. The measurements were performed in 0.1 M Tris buffer (pH 9.0) with a Clark type oxygen electrode at 28 °C. The epigallocatechin gallate concentration was fixed at 50 pm. The catechin stock solution was injected into the test solution at t = 0. The inset shows the (initial) steady-state autoxidation rate as a function of Cu2+ concentration. Reprinted from Biochimica et Biophysica Acta, vol. 1569, Mochizuki, M. Yamazaki, S. Kano, K. Ikeda,T., Kinetic analysis and mechanistic aspects of autoxidation of catechins, p. 35, Copyright (2002), with permission from Elsevier Science.

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].

Qu, quercetin K, kaempferol My, myricetin Lut, luteolin Apig, apigenin B-procyanidins EGC, epigallocatechin gallate C, catechin EC, epicatechin EGCG,... 

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

Nakagawa, K., Okuda, S., and Miyazawa, T., Dose-dependent incorporation of tea catechins, (—)-epigallocatechin-3-gallate and (—)-epigallocatechin, into human plasma, Biosci. Biotechnol. Biochem., 61, 1981, 1997. 

Lu, H., Meng, X., and Yang, C.S., Enzymology of methylation of tea catechins and inhibition of catechol-0-methyltransferase by (—)-epigallocatechin gallate. Drug Metab. Dispos., 31, 572, 2003. 

Flavonol Oxidation. The fermentation process is initiated by the oxidation of catechins (1) to reactive catechin quinones (13), a process catalyzed by the enzyme polyphenol oxidase (PPO) (56). Whereas the gallocatechins, epigallocatechin, and epigallocatechin gallate, are preferred, polyphenol oxidase can use any catechin (Table 2) as a substrate. This reaction is energy-dependent and is the basis of the series of reactions between flavanoids that form the complex polyphenolic constituents found in black and oolong teas. 

---