Polyphenols from tea

DEGENHARDT A, ENGELHARDT U H, LAKENBRINK 0 and WINTERHALTER P (2000) Preparative separation of polyphenols from tea by high-speed countercurrent chromatography , J Agric Food Chem, 48, 3425-30. 

Anthocyanidins from Ricciocarpos natans Proanthocyanidins from Stryphnodendron adstringens Proanthocyanidins from Cassipourea gummiflua Anthocyanins from plants Polyphenols from tea... 

Sava, V.M. et al., Isolation and characterization of melanic pigments derived from tea and tea polyphenols, Food Chem., 73, 177, 2001. 

Thousands of polyphenols from fruits (grapes, apples, etc.), vegetables (horse beans), and teas have been identified, many having good coloring properties, especially anthocyanins and some flavonoids. Well-documented reviews discuss the coloring capacities of some polyphenols including procyanidins. - Detailed presentations of anthocyanin and flavonoid properties and analysis are included in Sections 2.3, 4.3, and 6.3. The soluble proanthocyanidins of the colored horse bean Viciafaba L. seed coats were isolated and separated by solvent partition. 

Kyle JA, Morrice PC, McNeill G and Duthie GG. 2007. Effects of infusion time and addition of milk on content and absorption of polyphenols from black tea. J Agric Food Chem 55 4889-4894. 

Kamara, B.I. et al.. Polyphenols from honeybush tea Cyclopia intermedia), J. Agric. Food Chem., 51, 3874, 2003. 

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. 

In recent years, many studies demonstrated that topical application or oral feeding of a polyphenolic fraction from tea extract, or catechin derivatives, had anticarcino-genic effects in animal skin and other organs. ... 

In terms of cancer prevention, animal evidence of benefits from tea is based on in vitro studies which show that many reactions involved in tumour proliferation are either suppressed or blocked by tea polyphenols. It is believed that green tea has beneficial effects in reducing certain cancer types in some populations but a direct causal relationship in human trials needs to be established. Given the safety of tea and its potential to exert beneficial effects, such trials will undoubtedly be conducted in the near future. 

Bajaj, K. L., Anan, T., Tsushida, T., and Ikegaya, K. 1987. Effects of (-)-epicatechin on oxidation of theaflavins by polyphenol oxidase from tea leaves. Agric. Biol. Chem. 51 1767-72. 

Tanaka, T., Watarumi, S., Fujieda, M., and Kouno, I. 2005. New black tea polyphenol having V-ethyl-2-pyrrolidinone moiety derived from tea amino acid theanine Isolation, characterization and partial synthesis. Food Chem. 93 81-87. 

FIGURE 8.10 Scheme of the possible formation mechanism of thearubigins. (From Finger, A. 1994. In-vitro studies on the effect of polyphenol oxidase and peroxidase on the formation of polyphenolic black tea constituents. J. Sci. FoodAgric. 66 293-305. With permission.)... 

Challa, A., Katiyar, S.K., Cooper, K.D., and Mukhtar, H., Inhibition of UV-radiation-caused induction of oxidative stress and immunosuppression in C3H/HeN mice by polyphenols from green tea, J. Investigative Dermatol, accepted, 1998. 

Several flavonoids isolated from tea have been analyzed and their structure determined using NMR. There are several problems with the classical methods of analysis of flavonoids in tea. Due to the presence of complex mixtures of flavonoids in tea, they are often characterized as total polyphenols . The colorimetric method for analysis of total phenols can interfere with other reducing compovmds. LC can well resolve peaks for individual flavonoids however, there are only a few standards available commercially, making the assignment of peaks vmcertain in many cases. Thus, the structure of flavonoids giving rise to peaks in LC is often determined using various ID- and 2D-NMR experiments. 

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