Tea, polyphenolics extraction

J (2001) Green tea polyphenol extract attenuates inflammation in interleukin-2-deficient mice, a model of autoimmunity , J Nutr, 131 (7), 2034-9. 

Randomized placebo-controlled Phase II clinical trials are under way for the prevention of skin, oral, and lung cancers by topical or oral administration of Polyphenon E or other tea polyphenol extracts. 

Green tea polyphenol extract (10 g, Upton Company) was dissolved in 95% ethanol solution and the solution loaded onto a Sephadex LH-20 column (38 mm i.d. X 45 mm). After being eluted with 95% ethanol and monitored by TLC [chloroform-methanol-water (3 1 0.2) as eluent], 700 mg EGC and 1300 mg EGCG were yielded. 

The antibacterial effects of tea polyphenols extracted from Korean green tea (Camellia sinensis (L.) O. Kuntze (Theaceae)) against clinical isolates of methicil-lin-resistant Staphylococcus aureus (MRSA) were evaluated (Cho et al. 2008). Characterisation of the MIC of oxacillin for 30 Staphylococcus aureus strains isolated from patients treated with oxacillin identified 13 strains with an oxacillin MIC>4 pg/ml as MRSA (range 8-512 pg/ml), while 17 strains were methicillin-susceptible Staphylococcus aureus (MSSA range 0.25-0.5 pg/ml). The MICs of tea polyphenols ranged from 50 to 180 pg/ml for both the MSSA and the MRSA strains. The MICs of oxacillin for each of the 13 MRSA strains were reduced between 8- and 128-fold when these strains were coincubated with sub-MIC (<0.5 X MIC) levels of tea polyphenols, demonstrating that this combination was synergistic for all of the clinical MRSA isolates (Cho et al. 2008). 

Chemical Antioxidant Systems. The antioxidant activity of tea extracts and tea polyphenols have been determined using in vitro model systems which are based on hydroxyl-, peroxyl-, superoxide-, hydrogen peroxide-, and oxygen-induced oxidation reactions (109—113). The effectiveness of purified tea polyphenols and cmde tea extracts as antioxidants against the autoxidation of fats has been studied using the standard Rancimat system, an assay based on air oxidation of fats or oils. A direct correlation between the antioxidant index of a tea extract and the concentration of epigallocatechin gallate in the extract was found (107). 

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. 

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... 

Tea extracts and tea polyphenols inhibit copper- and peroxide-induced oxidation of LDL in vitro (116,123,124). The inhibitory concentration for 50% reduction (IC q) values for inhibition of copper-induced oxidation of LDL by some phenoHc antioxidants are Hsted in Table 7. The IC q for epigaHocatechin gaHate was found to be 0.075 p.mM, which was the most potent of all the phenoHc antioxidants tested (123,124). Similar results have been reported elsewhere (115,116,125,126). 

Unfortunately, to date, no formal clinical studies have been conducted to specifically evaluate the effects of green tea, green tea extracts, or EGCG on immune function. However, based on several Phase I studies that have evaluated EGCG and/or Polyphenon E (a defined, decaffeinated green tea polyphenol mixture) and found them to be safe and tolerable at relatively high doses, it is likely that future clinical studies may follow [66-69],... 

T. Nakatani, K. Ohtani, S. Sakanaka, CS059 M. Kim and I. Matsui-Yuasa. Protective effect of green tea extract and tea polyphenols against the cytotoxicity of 1,4-naphthoquinone in isolated rat hepatocytes. Biosci Biotech Biochem 1997 61(11) 1901-1905. 

Miketova, P. et al., Tandem mass spectrometry studies of green tea catechins. Identification of three minor components in the polyphenolic extract of green tea, J. Mass Spectrom., 35, 860, 2000. 

PhIP. The inhibition by tea of these two tests, which are indicators of genotoxicity, suggests that naturally occurring plant extracts can modify metabolic activation of HAAs. Tea polyphenols, epigallocatechin gallate from green tea and theaflavin gal-late from black tea, display similar inhibiting action in both tests (see ref. 318). 

Chen, C.W., and Ho, C.T., Antioxidant properties of polyphenols extracted from green and black teas, J. Food Lipid, 2, 35 6, 1994. 

White tea Water extracts Amino acids Polyphenols Caffeine Percentage... 

Miketova, R, Schram, K. H., Whitney, J., Li, M., Huang, R., Kerns, E., Valcic, S., Tim-mermann, B. N., Rourick, R., and Klohr, S. 2000. Tandem mass spectrometry studies of green tea catechins. Identification of three minor components in the polyphenolic extract of green tea. J. Mass Spectrom. 35 860-69. 

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