Polyphenols, fractionation

Biological Antioxidant Models. Tea extracts, tea polyphenol fractions, and purified catechins have all been shown to be effective antioxidants in biologically-based model systems. A balance between oxidants and antioxidants is critical for maintenance of homeostasis. Imbalances between free radicals and antioxidants may be caused by an increased production of free radicals or decreased effectiveness of the antioxidants within the reaction system. These imbalances can be caused by the radicals overwhelming the antioxidants within the system, or by an excess of antioxidants leading to a prooxidant functionaHty (105—118). When antioxidant defense systems are consistently overwhelmed by oxidative reactions, significant damage can... 

HAQQI T M, ANTHONY D D, GUPTA S, AHMAD N, LEE M S, KUMAR G K and MUKHTAR H (1999) Prevention of coUagen-induced arthritis in mice by a polyphenolic fraction from green tea , Proc Natl Acad Sci USA, 96 (8), 4524-9. 

Gomez-Caravaca AM, Carrasco-Pancorbo A, Canabate-Dlaz B, Segura-Carretero A and Fernandez-Gutierrez A. 2005. Electrophoretic identification and quantitation of compounds in the polyphenolic fraction of extra-virgin olive. Electrophoresis 26(18) 3538-3551. 

Gardana, C., Scaglianti, M., Pietta, P. and Simonetti, P. (2007) J. of Pharmaceutical and Biomedical Anal., Analysis of the polyphenolic fraction of propolis from different sources by liquid chromatography-tandem mass spectrometry, 45, 390-399. 

The polyphenol fraction, which was the most active of all the cranberry... 

Dissociation of the Protein-Poly phenolic Complex and Characterization of the Polyphenolic Fraction. Since Indulin ATR is almost completely soluble in THF while the APPL s are quite insoluble in this solvent, but are soluble in DMF, a sequence of different percentage mixtures of these two solvents was used in order to dissociate the protein-lignin complexes for further analyses of the lignin part. 

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. 

The Basic Protocol describes the reversed-phase HPLC analysis of polyphenolic compounds isolated into nonanthocyanin and anthocyanin fractions by solid-phase extraction. The Alternate Protocol describes the HPLC separation of acidic and neutral polyphenolic fractions. Fractionated samples are used because significant amounts of interfering compounds are extracted along with polyphenolics from plant materials. Solid-phase extraction with C18 Sep-Pak cartridges (vnitu.2) is used to selectively eliminate undesired components from crude extracts, and may minimize the effects of sample cleanup or preparation on the integrity of polyphenolics. The isolation and purification step using solid-phase extraction of polyphenolics will make possible the efficient analysis of individual polyphenolics by reversed-phase HPLC. 

Vernhet, A., Pellerin, R, Prieur, C., Osmianski, J., Moutounet, M. (1996). Charge properties of some grape and wine polysaccharide and polyphenolic fractions. Am. J. Enol. Vitic., 47, 25-30. 

Huang, M.T. et al.. Inhibitory effect of topical application of a green tea polyphenol fraction on tumor initiation and promotion in mouse skin. Carcinogenesis, 13,947,1992. 

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. ... 

The inhibitory effects of tea against carcinogenesis have been attributed to the biologic activities of the polyphenolic fractions in tea. However, the molecular... 

Figure 3.2 Flow diagram of grape polyphenolic fractionation procedure. (Reproduced from J. Agric. Food Chem., 2005, 53, 6003-6010, Lee etal., with permission from the American Chemical Society)...

Torres, J. B., Varela, M. T., Garcia, J., Carilla, C., Matito, J. J., Centelles, M., Cascante, X., Sort, R., and Bobet, A. (2002). Valorization of grape (Vitis vinifera) by products. Antioxidant and biological properties of polyphenolic fractions differing in procyanidin composition and flavonol content.. Agri. Food. Chem. 50, 7548-7555. 

The use of natural antioxidants in supplements can also exhibit pro-oxidant activity under certain conditions such as the concentration and nature of the polyphenolic compounds causing oxidative damage to important cellular components (48). Aqueous extracts and erode polyphenolic fractions of both traditional and green rooibos were evaluated for possible pro-oxidant activity using a Fenton reaction model system containing FeCb-EDTA and H2O2 for the generation of hydroxyl radicals. Pro-oxidant activity was shown for pure aspalathin while the dihydrochalcone and flavonoid contents of the enriched... 

Krishnan, R. and Maru, G. B. 2006. Isolation and analyses of polymeric polyphenol fractions from black tea. Food Chem. 94 331-40. 

FUKUDA, T., ITO, H., YOSHIDA, T., Effect of the walnut polyphenol fraction on oxidative stress in type 2 diabetes mice, BioFactors, 2004,21,251-253. 

Katiyar, S.K., Agarwal, R., Wood, G.S., and Mukhtar, H., Inhibition of 12-0-tetradecanoylphorbol-13-acetate-caused tumor promotion in 7,12-dimethylbenz[a]anthracene-initiated SENCAR mouse skin by a polyphenolic fraction isolated from green tea, Cancer Res., 52, 6890-6897, 1992c. 

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