thearubigin and epigallocatechin-gallate

Fungal laccase (EC 1.10.3.2) is an important enzyme for catalyzing the oxidation of tea polyphenols during the fermentation of tea. (-)-Epigallocatechin gallate (EGCG) is the main ingredient of tea polyphenols. To a certain extent, the oxidation degree of EGCG reflects the fermentation degree of tea. This study preliminarily optimized the conditions for catalytically oxidizing EGCG by Aspergillus sp. trijbl1112 laccase and systematically analyzed the components and contents of the EGCG oxidation products.. Aspergillus sp. trijbl1112 laccase oxidized EGCG into free catechins, ester catechins, gallic acid and tea pigments. The reaction conditions had a significant impact on the oxidation rate, types and concentrations of the products. At natural pH, 69.29% of EGCG was oxidized when 1 mL of EGCG (1 mmol L(-1) ) was catalyzed by 10 µg of fungal laccase for 150 min at 70 °C. When the EGCG oxidation rate was 69.27%, free catechins ((+)-catechin and (-)-epigallocatechin) and tea pigments (mainly thearubigin and theabrownin) constituted 48.42 and 38.87% of the oxidation products respectively.. The results may provide a theoretical basis for the application of EGCG oxidation using laccase and provide a novel technique for obtaining high production of tea pigments.

Topics: Anti-Infective Agents; Antineoplastic Agents, Phytogenic; Antioxidants; Aspergillus; Biflavonoids; Camellia sinensis; Catalysis; Catechin; Laccase; Oxidation-Reduction; Plant Extracts; Polyphenols; Tea

Green and black teas contain different biologically active polyphenolic compounds that might offer protection against a variety of human diseases. Although promising experimental and clinical data have shown protective effects, limited information is available on how these beneficial effects of tea polyphenols are mediated at the cellular level. Evidence is accumulating that catechins in green tea as well as theaflavins and thearubigins from black tea are the substances responsible for the physiologic effects of tea in vitro. The green tea catechin epigallocatechin-3-gallate (EGCG) is generally considered to be the biologically most active compound in vitro. The changes in the activities of various protein kinases, growth factors, and transcription factors represent a common mechanism involved in cellular effects of tea polyphenols. In addition to modification of intracellular signaling by activation of cellular receptors, it was shown that, at least for EGCG, tea polyphenols can enter the cells and directly interact with their molecular targets within cells. There, they frequently result in opposite effects in primary compared with tumor cells. Although tea polyphenols were long regarded as antioxidants, research in recent years has uncovered their prooxidant properties. The use of high nonphysiologic concentrations in many cell culture studies raises questions about the biological relevance of the observed effects for the in vivo situation. Efforts to attribute functional effects in vivo to specific molecular targets at the cellular level are still ongoing.

Topics: Animals; Antioxidants; Biflavonoids; Camellia sinensis; Catechin; Humans; Neoplasms; Oxidants; Phytotherapy; Plant Extracts; Polyphenols; Signal Transduction; Tea

Sulfotransferase (SULT) 1A1 and SULT1A3 play important roles in the presystemic inactivation of beta(2) agonists in the liver and intestine, respectively. The study aimed to investigate the inhibitory effects of grapefruit juice, orange juice, green tea, black tea and oolong tea and their constituents on the activities of SULT1A1 and SULT1A3. The activities of both SULT1A1 and SULT1A3 were significantly inhibited by all the beverages investigated at a concentration of 10%. The beverage constituents were tested in concentration ranges considered to be physiologically relevant. The grapefruit constituent, quercetin, completely inhibited SULT1A1, while quercetin and naringin both partially inhibited SULT1A3. The orange constituents, tangeretin and nobiletin, also completely inhibited SULT1A1. The tea constituents, (-)-epicatechin gallate and (-)-epigallocatechin gallate, both almost completely inhibited SULT1A1 and SULT1A3. Moreover, the theaflavin and thearubigin fractions of black tea both completely inhibited SULT1A1 and strongly inhibited SULT1A3. The inhibitory action of green tea on SULT1A3 was competitive, while that of black tea and oolong tea was mixed competitive/non-competitive. Mechanism-based inhibition was not observed with any beverage. In conclusion, various beverages, especially teas, inhibit the function of SULT1A3, and therefore may have the potential to increase the bioavailability of orally administered substrates of SULT1A3, such as beta(2) agonists.

Topics: Adrenergic beta-Agonists; Arylsulfotransferase; Beverages; Biflavonoids; Biological Availability; Catechin; Citrus paradisi; Citrus sinensis; Flavanones; Flavones; Herb-Drug Interactions; Humans; In Vitro Techniques; Phenols; Polyphenols; Quercetin; Sulfotransferases; Tea

To prepare tea pigments.. Tea pigments are prepared by solvent extraction from Sri lanka black tea.. Tea pigments contains the components as follows: caffeine 1.77%, epigallocatechin 1.37%, catechin 1.20%, epicatechin 9.55%, epigallocatechin gallate 10.52%, epicatechin gallate 9.94%, theaflavin 10.34%, theaflavin monogallate 9.57%, theaflavin digallate 4.81%, thearubigin about 40.93%.. The best proportions of the compound that are obtained with HPLC analysis.

Topics: Biflavonoids; Caffeine; Catechin; Chromatography, High Pressure Liquid; Gallic Acid; Phenols; Pigments, Biological; Polyphenols; Tea

The phenolic composition and antioxidant activities [TEAC, ORAC, FRAP] of consumer brews (1 tea bag in 230 ml for 1 min) of seven different brands of black tea from the British market were investigated. The main phenolic compounds identified were epigallocatechin gallate, four theaflavins, as well as epicatechin gallate, theogallin (tentative assignment), quercetin-3-rutinoside and 4-caffeoyl quinic acid. Thearubigins represented an estimated 75-82% of the total phenolics. Further, polyphenol fractions were in decreasing order theaflavins, flavan-3-ols, flavonols, gallic acids and hydroxycinnamates. On average, a cup of a consumer brew of black tea is providing polyphenols at the level of 262mg GAE/serving, of which 65 mg were assigned to individual polyphenols. The antioxidant activity of black tea preparations is higher than that of most reported dietary agents on a daily basis. Correlations were observed between the antioxidant activities and the sum of all quantified polyphenols by HPLC analysis as well as with the total phenolics. Treatment of the black tea brew with simulated gastric juice resulted in a significant increase of the identified theaflavins implying a partial cleavage of thearubigins in the environment of the gastric lumen. Therefore, black tea can be considered to be a rich source of polyphenols and/or antioxidants.

Topics: Antioxidants; Biflavonoids; Camellia sinensis; Catechin; Coumaric Acids; Diet; Flavonoids; Flavonols; Gallic Acid; Gastric Juice; Humans; Phenols; Plant Leaves; Polymers; Polyphenols; Tea

Previous studies in our laboratory have shown that the major green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), suppressed autophosphorylation of epidermal growth factor (EGF) receptor induced by EGF in human A431 epidermoid carcinoma cells. In this study, we examined the inhibitory effects of black tea polyphenols, including theaflavin (TF-1), a mixture (TF-2) of theaflavin-3-gallate (TF-2a) and theaflavin-3'-gallate (TF-2b), theaflavin-3,3'-digallate (TF-3) and the thearubigin fraction on the autophosphorylation of the EGF and PDGF receptors in A431 cells and mouse NIH3T3 fibroblast cells, respectively. First, we examined the effects of these polyphenols on the proliferation of A431 and NIH3T3 cells. Both EGCG and TF-3 strongly inhibited the proliferation of A431 and NIH3T3 cells more than the other theaflavins did. In cultured cells with pre-treatment of tea polyphenol, TF-3 was stronger than EGCG on the reduction of EGF receptor and PDGF receptor autophosphorylation induced by EGF and PDGF, respectively. Other theaflavins slightly reduced the autophosphorylation of the EGF and PDGF receptors; furthermore, TF-3 could reduce autophosphorylation of the EGF receptor (or PDGF receptor) even with co-treatment with EGF (or PDGF) and TF-3, but EGCG was inactive under these conditions. In addition, TF-3 was stronger than EGCG in blocking EGF binding to its receptor. These results suggest that not only the green tea polyphenol, EGCG, but also the black tea polyphenol, TF-3, have an antiproliferative activity on tumor cells, and the molecular mechanisms of antiproliferation may block the growth factor binding to its receptor and thus suppress mitogenic signal transduction.

Topics: 3T3 Cells; Animals; Biflavonoids; Carcinoma, Squamous Cell; Catechin; Cell Division; Epidermal Growth Factor; ErbB Receptors; Gallic Acid; Growth Inhibitors; Humans; Laryngeal Neoplasms; Mice; Phenols; Phosphorylation; Platelet-Derived Growth Factor; Polyphenols; Protein Binding; Protein Processing, Post-Translational; Receptors, Platelet-Derived Growth Factor; Signal Transduction; Tea; Tumor Cells, Cultured