Polyphenols in tea

Kiehne, A. and Engelhard , U.FI., Thermospray-LC-MS analysis of various groups of polyphenols in tea. Part 1. Catechins, fiavonol 0-glycosides, and flavone C-glycosides, Z. Lebensm. Unters. 

Aqueous tea extracts deteriorate rapidly during storage. They develop an undeslreable taste commonly described as "flat" and concurrently turn dark brown in color. Roberts et al. (56) used a modification of the HPLC procedure of Hoefler and Coggon T57) to separate the polyphenols in tea to study this problem. The effluent from the reverse phase acetone gradient was monitored at 380 nm. 

Roberts, E. A. H., and Wood, D. J. 1951b. The separation of polyphenols in tea leaf by paper chromatography with water as a mobile solvent. Biochem. J. 49, xxxiii. 

FOTiest GI, Boidall DS (1969) Distribution of polyphenols in tea plants Camellia sinensis L). BiochemJ 113 741-755... 

Ding M, Yang H, Xiao S (1999) Rapid, direct determination of polyphenols in tea by reversed-phase column liquid chromatography. J Chromatogr A 849 637-640... 

Long H, Zhu Y, Huang T, Coury LA, Kissinger PT (2001) Identification and determination of polyphenols in tea by liquid chromatography with multi-channel electrochemical detection. J Liq Chromatogr Relat Technol 24 1105-1114... 

Suteerapataranon, S. andD. Pudta. 2008. Flow injection analysis-spectrophotometry for rapid determination of total polyphenols in tea extracts. J. Flow Injection Anal. 25(l) 61-64. 

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. 

JAVED s, MEHROTRA N K and SHUKLA Y (1998) Chemopreventive effects of black tea polyphenols in mouse skin model of carcinogenesis , Biomed Environ Sci, 11 (4), 307-13. 

LAKENBRiNK c, LAPCZYNSKi s, MAiwALD B and ENGELHARD u H (2000) Flavonoids and Other polyphenols in consiuner hrews of tea and other caffeinated beverages , JAgric Food Chem, 48, 2848-52. 

LEE M J, WANG Z Y, LI H, CHEN L, SUN Y, GOGGO S, BALENTINE D A and YANG C S (1995) Analysis of plasma and urinary tea polyphenols in human subjects , Cancer Epidem Biomed Prev, 4, 393-9. 

ROBERTS E A H and MYERS M (1958) Theogallin, a polyphenol occurring in tea. 11. Identification as a gaUoyl quinic acid , J Sci Food Agric, 9, 701-5. 

SAKANAKA s (1995) Anti-caries and anti-periodontal disease effects of green tea polyphenols , in Proc of Intern Symp on Tea-Quality-Human Health, 7-10 December, 1995, Shanghai, China, 97-106. 

As indicated in Table 2, the polyphenols constitute the most abundant group of compounds in tea leaf. Of these, the epi- form of the catechin group of fiavanois predominate. Their structure is shown in Figure 2. 

Caffeine contained in tea beverage is absorbed at about the same rate as caffeine in coffee, cola drinks, or in pure water. Data to support this conclusion was obtained in a human feeding experiment.109 The theory that complexation of caffeine with the polyphenolic material in tea retards absorption110-111 is not borne out. 

Polyphenoloxidase (PPO, EC 1.14.18.1) is one of the most studied oxidative enzymes because it is involved in the biosynthesis of melanins in animals and in the browning of plants. The enzyme seems to be almost universally distributed in animals, plants, fungi, and bacteria (Sanchez-Ferrer and others 1995) and catalyzes two different reactions in which molecular oxygen is involved the o-hydroxylation of monophenols to o-diphenols (monophenolase activity) and the subsequent oxidation of 0-diphenols to o-quinones (diphenolase activity). Several studies have reported that this enzyme is involved in the degradation of natural phenols with complex structures, such as anthocyanins in strawberries and flavanols present in tea leaves. Several polyphenols... 

Sakakibara H, Honda Y, Nakagawa S, Ashida H and Kanazawa K. 2003. Simultaneous determination of all polyphenols in vegetables, fruits, and teas. J Agric Food Chem 51 (3) 571—581. 

The various chemical processes influencing the colour formation in tea have been vigorously investigated. The self-association of black tea polyphenol theaflavin and its com-plexation with caffeine [175], and the role of epicatechin quinone in the synthesis and degradation of theaflavin [176] have been studied in detail. 

The polyphenols in beer, fruit juices, and tea are typically members of the flavan-3-ols (see Fig. 2.8) and the proanthocyanidins constructed from them. 

Lin, Y. L., I. M. Juan, Y. L. Chen, Y. C. Liang and J. K. Lin. Composition of polyphenols in fresh tea leaves and associations of their oxygen-radical-absorbing capacity with antiproliferative actions in fibroblast cells. J Agr Food Chem 1996 44(6) 1387-1394. Davis, A. L., Y. Cai, A. P. Davies and J. R. Lewie. H and NMR assignments of some green tea polyphenols. Magn Reson Chem 1996 34(11) 887-890. 

Zaprometov, M. N., N. V. Zagoskina and T. F. Koretskaya. Effect of some precursors on the formation of phenolic compounds in tea plant tissue cultures. Fiziol Rast 1976 23 1274. Higashi-Okai, K., S. Otani and Y. Okai. Potent suppressive activity of pheophytin A and B from the non-polyphenolic fraction of green tea (Camellia sinensis) against tumor promotion in mouse skin. Cancer Lett 1998 129(2) 223-228. 

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