Tea , theaflavins and

Robertson, A. and Bendall, D. S. 1983. Production and HPLC analysis of black tea theaflavins and thearubigins during in vitro oxidation. Phytochemistry 22 883-87. 

Yoshino, K., Kara, Y, Sano, M., and Tomita, I. 1994. Antioxidative effects of black tea theaflavins and thearubigins on lipid peroxidation of rat liver homogenates induced by less butylhydroperoxide. Biol. Pharm. Bull. 17 146-49. 

Ramji, D., Sang, S., Liu, Y., Rosen, R. T., Ghai, G., Ho, C. T., Yang, C. S., and Huang, M. T. 2005. Effect of black tea theaflavins and related benzotropolone derivatives on 12-0-tetradecanoylphorbol-13-acetate-induced mouse ear inflammation and inflammatory mediators. In Phenolic compounds in foods and natural health products, ed. F. Shahidi and C. T. Ho, 242-53. Washington, DC American Chemical Society. 

LEE B L and ONG c N (2000) Comparative analysis of tea catechins and theaflavins by high-performance liquid chromatography and capillary electrophoresis , J Chromatog A, 881 (1-2), 439-47. 

The kinetics of tea extraction have been studied in detail 89 90 Rates for caffeine, theaflavin, and thearubigen extraction have been determined. It has been demonstrated that extraction is not a transport-controlled process. Temperature and time are the rate-limiting variables. 

Roberts, E. A. H. and Smith, R. F., Spectrophotometric measurements of theaflavins and thearubigens in black tea liquors in assessments of quality in teas. Analyst (Bond), 86 94, 1961. 

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. 

Another experiment was carried out by adjusting the pH of the water and then they were employed for the preparation of the tea infusion. HPLC resulted in the separation of more than 50 components in the broken black tea infusion as demonstrated in Fig. 2.69. Unfortunately, the majority of peaks have not been identified and the chromatographic profiles only indicate the presence of many compounds in the infusions. Some results are presented in Table 2.66. The measurement indicated that theaflavins and tea catechins play a decisive role in the formation of cream particles and tea colour [184],... 

RP-HPLC with gradient elution was employed for the study of the influence of theaflavins and thearubigins on the adsorption of black tea on calcium carbonate. Separation of tea constituents was performed in an ODS column (250 X 4.9mm i.d. particle size 5 im). Aqueous solvent was 1 per cent citric acid, pH adjusted to 2.8 with sodium hydroxide and the organic solvent was ACN. The gradient initiated at 8 per cent ACN, was increased to 31 per cent in 50min. Theaflavins and thearubigins were detected at 460 nm, while total polyphenolics were detected at 280 nm. The flow rate was 1.5 ml/min. The results demonstrated the involvement of theaflavins and thearubigins in the adsorption process [185],... 

A.J. Charlton, A.L. Davis, D.P. Jones, J.R. Lewis, A.P. Davies, E. Haslam and M.P. Williamson, The self-association of black tea polyphenol theaflavin and its complexation with caffeine. J. Chem. Soc. Perkin Trans. 2 (2000) 317-322. 

Menet, M.C. et al., Analysis of theaflavins and thearubigins from black tea extract by MALDI-TOF mass spectrometry, J. Agric. Food Chem., 52, 2455, 2004. 

The inhibitory effects of tea polyphenols on xanthine oxidase (XO) were investigated. Theaflavins and EGCG inhibit XO to produce uric acid and also act as scavengers of superoxide. Theaflavin 3,3 -digaUate (TE-3) acts as a competitive inhibitor and is the most potent inhibitor of XO among these compounds. TE-3 also inhibited the superoxide production in HL-60 cells. Therefore, the antioxidative activity of tea polyphenols is due not only to their ability to scavenge superoxides but also to their ability to block XO and relative oxidative signal transducers. ... 

Sazuka, M., Imazawa, H., Shoji, Y, et al.. Inhibition of collagenases from mouse lung carcinoma cells by green tea catechins and black tea theaflavins, Biosci. Bio-technol. Biochem. 61, 1504-1506, 1997. 

Polyphenolic catechins and theaflavins exist as either monomers or polymers in green and black teas, respectively, and are both well known to be inhibitory and bactericidal against Streptococcus spp. They bind to surface proteins of the bacteria, and induce aggregation and inhibit the enzymatic activity of glucosyl transferase. Both teas inhibit salivary and streptococcal amylase, overall, leading to reduction in plaque. Studies in animals have shown that tea consumption reduces caries, and it has been associated with lower caries levels in humans. ... 

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