Thearubigins Research Articles

Protective effects of black tea extract on testosterone induced oxidative damage in prostate

Since ancient times, antipyretic, anti-inflammatory, antimicrobial and antioxidative properties of tea have been recognized. Black tea ( Camellia sinensis) contains a variety of polyphenolic ingredients including the theaflavins (TF), thearubigins (TG) and catechins. Components from black tea have been accounted to play an important role in scavenging free radicals generated by mutagens and carcinogens. Androgens are the key factors in either the initiation or progression of prostate cancer (PCA) by inducing oxidative stress. In the present set of investigations, the antioxidative potential of black tea extract against androgen mediated oxidative stress in male Wistar rats has been studied. Testosterone was given at a dose of 5 mg/kg b.w. subcutaneously, consecutively for 5 days. Prior to androgen administration, animals were kept on 0.5, 1.0 and 1.5% aqueous tea extract (ATE) as sole source of drinking fluid for 15 days. The prostate tissue was dissected out for biochemical analysis for antioxidant enzymes viz. catalase (CAT), superoxide dismutase (SOD), lipid peroxidation (LPO), glutathione- s-transferase (GST) and glutathione reductase (GR). The results revealed that testosterone administration induced the oxidative stress in rat prostate, however, in 0.5, 1.0 and 1.5% ATE supplemented groups, a significant protective effect of black tea against testosterone induced oxidative injury was recorded. Hence, the study reveals that constituents present in black tea impart protection against androgen induced oxidative injury that may result in development of prostate cancer.

Phenolic compounds in tea from Australian supermarkets

Phenolic compounds constitute 50–70% of tea water extract and are the main quality parameters for teas. Theaflavins (TF), thearubigins (TR) and theabrownins (TB) are the major polyphenols that determine the quality of black tea. These compounds were measured in 56 leaf teas and teabags sampled from Australian supermarkets in Queensland. The various quantities of TF, ranging from 0.29% to 1.25%, indicate a quality difference that exists among the teas studied. Low TF content in black tea may be due to over-fermenting and/or long periods of storage. The solubility of TR and TB from teabags ranged from 82% to 92%, indicating that the permeability of teabags was variable. Variable quantities of TF in Australian teas show instability and a tendency of TF to oxidize during storage. Total polyphenols in green teas ranged from 14% to 34%, indicating a large variation, which was not reflected in price. The solubility of total polyphenols from teabags has been proposed as a useful quality index of the filtering paper used for the teabags. This chemical analysis of phenolic compounds in commercial teas may be a potential tool for the quality control of Australian manufactured and imported teas in Australian markets.

Inhibition of benzo[ a]pyrene induced mutagenicity and genotoxicity by black tea polyphenols theaflavins and thearubigins in multiple test systems

This study investigated the antimutagenic and anticlastogenic effects of black tea polyphenols, theaflavins (TF) and thearubigins (TR) in Salmonella assay in vitro and in vivo in bone marrow cells of mice as measured by chromosomal aberrations (CA) and sister chromatid exchange (SCE) against a known carcinogen, benzo[ a]pyrene (B[ a]P). A significant decrease in mutagenicity in Salmonella assay and both CA and SCE were observed in all the different concentrations of TF and TR plus B[ a]P treated series when compared with B[ a]P treated group alone. These results indicate that both TF and TR have significant antimutagenic and anticlastogenic effects.

A reliable technique to identify superior quality clones from tea germplasm

Variations in the substrate level and enzyme activity of prominent south Indian tea germplasm were studied. The content of polyphenols, catechins (substrates) and polyphenol oxidase (PPO) showed variation, which influenced the final black tea quality. The enzyme PPO occurs in tea shoots and catalyzes the reactions between catechins to form theaflavins in the presence of oxygen. The catechins mainly epicatechin (EC), epigallo catechin gallate (EGCG), epicatechin gallate (ECG) and epigallo catechin (EGC) get mixed with PPO during the oxidation process to form quality constituents like theaflavins (TF), thearubigins (TR) and high polymerized substances (HPS). Theaflavins and their fractions such as simple theaflavin, theaflavin monogallate, (TFMG), theaflavin digallate (TFDG) in black tea are the essential quality constituents that are responsible for the liquor characteristics where as TR and high polymerized substances impart colour to the liquor. As oxidation of macerated leaves proceed through different stages of tea manufacture, a decline in PPO activity, polyphenol and catechin contents were observed. Data revealed that the oxidation reaction was faster during the initial stages of oxidation. During the period, oxygen consumption was higher and declined thereafter. Ratio between the enzyme (PPO) and its substrate (catechins) were used to characterize the quality potential of tea clones. An attempt has also been made to categorize prominent tea clones as high, moderate and average quality clones based on their enzyme substrate ratio. Theaflavin content (oxidation product) of different tea clones suggests that the ratio between PPO and catechins forms an important criterion which determines black tea quality. Results obtained were compared with standard clones of known high quality (CR-6017) and moderate quality (SA-6). The study reveals that the enzyme substrate ratio can be used to identify superior quality clones from the existing tea germplasm.

India levies duties of up to $358 per tonne on Chinese anatase TiO 2

A study was conducted over a period of 5 years to quantify the quality characteristics of CTC (crush, tear and curl) black teas produced in Wayanad, Central Travancore, Anamallais, High Range, Nilgiris and Chikmagalur areas of south India and their correlation with organoleptic evaluation. Quality characteristics such as theaflavins (TF), thearubigins (TR), highly polymerised substances (HPS), total liquor colour (TLC), TR/TF ratio and colour index (CI) were estimated. Teas from Karnataka, Nilgiris and Anamallais had the highest theaflavin content and better TR/TF ratio than the teas from Travancore, High Range and Wayanad regions. A significant positive correlation of theaflavin content with the values of thearubigins, total liquor colour, colour index, infused leaf appearance (ILA) and taste (TAS) was observed.

India: Travancore Titanium — TiO 2

A study was conducted over a period of 5 years to quantify the quality characteristics of CTC (crush, tear and curl) black teas produced in Wayanad, Central Travancore, Anamallais, High Range, Nilgiris and Chikmagalur areas of south India and their correlation with organoleptic evaluation. Quality characteristics such as theaflavins (TF), thearubigins (TR), highly polymerised substances (HPS), total liquor colour (TLC), TR/TF ratio and colour index (CI) were estimated. Teas from Karnataka, Nilgiris and Anamallais had the highest theaflavin content and better TR/TF ratio than the teas from Travancore, High Range and Wayanad regions. A significant positive correlation of theaflavin content with the values of thearubigins, total liquor colour, colour index, infused leaf appearance (ILA) and taste (TAS) was observed.

Comparative study of cream in infusions of black tea and green tea [Camellia sinensis (L.) O. Kuntze

Summary Particle size, concentration and chemical composition of green‐tea cream and black‐tea cream were studied. Tea‐cream particle size tended to decrease during tea fermentation and average size of tea‐cream particles was bigger for green than for black tea. The amount of tea‐cream formed in tea infusions depended on their chemical composition. Tea catechins and their oxidation products formed tea‐cream when they interact with some non‐catechin compounds in tea liquor. Model fermentation tests revealed that little tea‐cream was found in solution of crude tea catechins and the tea‐cream formed after fermentation did not significantly increased in the crude tea catechins solution. Tea extract prepared at 50 °C formed less tea‐cream than those prepared at 90 °C before and after fermentation. Caffeine, gallocatechin (GC) and epigallocatechin gallate (EGCG) were the predominant compounds in green‐tea cream but thearubigins (TRs), caffeine and theaflavins (TFs) in black‐tea cream. Gallated catechins and gallated TFs had stronger creaming ability than un‐gallated catechins and TF. How to control tea liquor from creaming down is discussed.

Anticlastogenic effects of black tea (World blend) and its two active polyphenols theaflavins and thearubigins in vivo in Swiss albino mice

This study investigated the inhibition of cyclophosphamide (CP) and dimethylbenz(a)anthracene (DMBA) induced genetic damage by black tea (World blend) and its two active polyphenols theaflavins (TF) and thearubigins (TR) in Swiss albino mice as measured by chromosome aberrations (CA) and sister chromatid exchanges (SCE). Three different concentrations (5, 10 and 20%) of tea and a single dose of TF and TR were tested for their anticlastogenic effects against DMBA (50 mg/kg body weight) and CP (20 mg/kg for CA and 10 mg/kg for SCE). A significant decrease in CA was observed in all the three concentrations of tea extract plus DMBA treated groups when compared with the respective DMBA treated group alone. Similarly a significant decrease in CA was observed in all the three concentrations of tea extracts plus CP treated series when compared with the group treated with CP alone. In SCE assay, a significant decrease in SCE was observed in 5, 10 and 20% black tea extract plus CP and 10 and 20% tea extracts plus DMBA treated groups when compared with the CP or DMBA treated group alone. In the single dose of TF and TR treated groups a significant decrease in both CA and SCE was observed in both the TF and TR plus both the carcinogen treated groups when compared with their positive controls. The protective effects of black tea extracts were more significant than that of its two polyphenols. This study indicates that both black tea and its active polyphenols TF and TR have significant anticlastogenic effects in bone marrow cells of mice.

Novel approaches to chemoprevention of skin cancer.

Protection against sun-induced damage leading to photocarcinogenesis in skin is a highly desirable goal. Among various strategies, chemopreventive approaches utilizing non-toxic agents to prevent the occurrence of precancerous lesions or their surrogate markers are potentially attractive. Epidemiological and experimental studies provide evidence that some naturally occurring chemical agents in the human diet can diminish cancer risk. Aside from water, tea is the most common beverage consumed worldwide. Black tea accounts for nearly 80% of total tea production. Black tea and green tea are derived from the same plant, Camelia sinensis. Green tea contains monomeric polyphenols known as flavanols and black tea contains dimeric flavanols and polymeric polyphenols known as theaflavins (TFs) and thearubigins (TRs). Over the past fifteen years our laboratory has been exploring the feasibility of using tea and its constitutents as an approach to skin cancer prevention. We demonstrated that green tea, black tea and constituent polyphenols protect against chemical- and ultraviolet B (UVB)-induced carcinogenesis and reduce the growth of established tumors in skin. We have also shown the efficacy of green and black tea extracts against UVB and psoralen + ultraviolet A (PUVA)-induced early damage in skin. Although PUVA is highly effective in treating certain skin diseases, careful follow-up studies of cohorts of patients have shown that similar to UVB, PUVA treatment increases the risk for cutaneous squamous cell carcinoma and melanoma. We have found that oral administration of a standardized green tea extract (SGTE) prior to and during treatment of SKH-1 mice diminished PUVA-induced skin hyperplasia and hyperkeratosis. SGTE-treatment also inhibited PUVA-induced accumulation of c-fos and p53 proteins and epithelial hyperproliferation. Both topical application and oral administration of SGTE after PUVA-treatment reduced skin inflammation and cell hyperproliferation. Topical application of SGTE to human skin prior to PUVA-treatment inhibited the delayed skin inflammatory response. Similarly, oral and topical administration of standardized black tea extract (SBTE) and its two major polyphenolic sub-fractions protect against UVB-induced erythema in SKH-1 mice. Furthermore, topical application of tea extracts to human volunteers protects against UVB-induced erythema. In summary, these studies indicate that tea extracts are effective in reducing UVB- and PUVA-mediated DNA damage, expression of early response genes and early inflammatory changes in skin. These studies verify a conceptual rationale for employing naturally occurring dietary constitutents as an approach to cancer chemoprevention.

Inhibition of 1,2-dimethylhydrazine-induced oxidative DNA damage in rat colon mucosa by black tea complex polyphenols

The effect of black tea polyphenols on 1,2-dimethylhydrazine (DMH)-induced oxidative DNA damage in rat colon mucosa has been investigated. Fischer 344 rats were treated orally with thearubigin (TR) or theafulvin (TFu) for 10 days (40 mg/kg), injected ip with DMH (20 mg/kg) or saline and sacrificed 24 hr after DMH administration. The levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG) were measured in colonic mucosa DNA and expressed as a ratio relative to 2′-deoxyguanosine (2dG). Control rat mucosa had 8-OHdG values of 1.12 ± 0.14/10 5 dG (mean ± SEM, n=11), whereas DMH-treated rats significantly higher values (1.52 ± 0.14/10 5 dG, n=26, P<0.05). Pretreatment of rats with TR had significantly inhibited DMH-induced oxidative DNA damage 0.99 ± 0.09/10 5 dG, n=10, P<0.05) and a similar, although less marked, effect was observed with TFu (1.15 ± 0.19/10 5, n=9, P=0.06). These findings confirm that DMH causes oxidative DNA damage in the colon mucosa of rats and demonstrate that this effect is prevented by the consumption of complex polyphenols from black tea.

Isolation of black tea pigments using high-speed countercurrent chromatography and studies on properties of black tea polymers.

Isolation of theaflavins and epitheaflavic acids from black tea using high-speed countercurrent chromatography (HSCCC) on a preparative scale is demonstrated. HSCCC also enabled the isolation of a polymeric fraction from black tea. According to Roberts' classification, the polymeric fraction mainly consisted of SII thearubigins (TR). HPLC analysis showed that the isolated material is free of any known chromatographically resolved tea constituents and eluted from reversed-phase packings as a convex "hump" (a broad signal). The antioxidant activity of the TR fraction was 3.6 mmol of Trolox equivalents per gram. The total phenolic content of this fraction was determined to be 34.7 g/100 g (as gallic acid equivalents).

Synergistic effects of thearubigin and genistein on human prostate tumor cell (PC-3) growth via cell cycle arrest

There is evidence that habitual consumption of green tea by Japanese men is correlated with a reduction in cancers, including prostate; soybean isoflavones are also associated with increased protection. The present study compared the anti-proliferative effect of black tea ( Camellia sinensis) polyphenol, thearubigin (TR), alone or combined with the isoflavone genistein, on human prostate (PC-3) carcinoma cells. TR administered alone did not result in any alteration of cell growth. When combined with genistein, however, TR significantly inhibited cell growth and induced a G2/M phase cell cycle arrest in a dose dependent manner. These findings indicate the potential use of combined phytochemicals to provide protection against prostate cancer.

Inhibition of TPA-induced protein kinase C and transcription activator protein-1 binding activities by theaflavin-3,3'-digallate from black tea in NIH3T3 cells.

Tea is one of the most popular beverages in the world. Several reports have shown that both green tea and black tea were able to inhibit tumor cell proliferation in animal models. In this study, we investigated the inhibitory effects of black tea polyphenols including theaflavin (TF-1), the mixture (TF-2) of theaflavin-3-gallate (TF-2a), and theaflavin-3'-gallate (TF-2b), theaflavin-3,3'-digallate (TF-3), thearubigin (TR), and a major green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) on 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced protein kinase C (PKC) and transcription activator protein-1 (AP-1) binding activities in NIH3T3 cells. On analysis of PKC activity with partial purified preparation, TPA (100 ng/mL) treatment was able to elevate membrane-associated PKC activity approximately 3-fold, and treatment with TF-3 (20 microM) and EGCG (20 microM) showed 94.5% and 9.4% suppression on TPA-induced PKC activity, respectively. Translocation of PKCalpha protein from cytosol to membrane was detected in TPA-treated NIH3T3 cells, and TF-3 was able to block its translocation. By in vitro kinase assay using myelin basic protein (MBP) as a PKC-specific substrate, we found that TPA treatment was able to increase PKC kinase activity by detection of phosphorylated MBP protein and TF-3 showed strongest inhibitory effect on its phosphorylation while EGCG was shown to be less effective. We also analyzed the AP-1 binding activity by electrophoretic mobility shift assay and c-Jun gene expression by northern blot and western blot, the results showed that TF-3 is the most potent inhibitor on TPA-induced AP-1 binding activity and c-Jun gene expression among these five tea polyphenols. Our results might provide new molecular basis for understanding the inhibitory effects of tea polyphenols on TPA-mediated tumor promotion.

Rapid method for measuring thearubigins and theaflavins in black tea using C18 sorbent cartridges

AbstractThis communication describes the routine use of small inexpensive C18 cartridges for rapid separation and accurate measurement of both thearubigins (TR) and theaflavins (TF) in a liquor brewed from black tea. The slow, traditional method overestimates TR content because of interference from flavonol glycosides. Comparison is also made favourably with other methods available for estimating total TF and sometimes TR in tea.

Response of tea quality parameters to time of year and nitrogen fertiliser

AbstractThough tea production continues throughout the year in Kenya, there ere monthly variations in yields and chemical composition attributable to the changes in environmental conditions. Total volatile flavour compounds (VFC), group I VFC, group II VFC and caffeine ere higher throughout the experimental period in black teas manufactured from plants here fertilisers ere applied than here fertiliser as not applied. Levels of thearubigins (TR) and flavour index (FI) ere generally high hen there as no fertiliser application. Theaflavins (TF) levels varied ith the time of the year but there as no clear trend due to fertiliser.

The effects of altitude on the chemical composition of black tea

AbstractChanges in quality parameters of crush, tear and curl (CTC) black clonal teas due to variations in altitude within a radius of 10 km were determined. There were significant (P = 0.05) changes in all the quality parameters due to areas of production despite the short sampling radius. The Group I volatile flavour compounds (VFC) increased with decrease in altitude whereas Group II VFC and flavour index (FI), theaflavins (TF), thearubigins (TR) (except in clone TN 14‐3) and caffeine increased with increase in altitude. The tasters' evaluation also increased with increase in altitude.

Seasonal variations in theaflavin, thearubigin and caffeine contents of argentinian black teas

AbstractThirty‐three Argentinian black tea samples of three grades (BOP, BOPF and PF) obtained fortnightly were examined for their theaflavin (TF), thearubigin (TR) and total and extractable caffeine contents during the 1985/86 season. Total and extractable caffeine contents decreased gradually during most of the season after an early rapid increase. TF contents fluctuated following climatic variations, decreasing after rainy periods. Total colour and TF curves were consistent with there being a good linear correlation between them, whereas TR showed erratic fluctuations throughout the whole season.

The effect of withering on fermentation of tea leaf and development of liquor characters of black teas

AbstractDepression in polyphenol oxidase (PPO) activity during the withering of tea leaf (Camellia sinensis) in black tea manufacture affected the oxidative‐condensation of tea flavanols in forming theaflavins (TF) and thearubigins (TR), which are associated with brightness, briskness and ‘body’ of tea liquors. In contrast to conventionally manufactured CTC teas, unwithered fresh leaf CTC produces a higher proportion of TF and lower TR, resulting in bright, brisk and thin liquors. Hardness of wither was accompanied by a further depression in PPO activity, and formation of TF also declined with a concomitant loss in brightness and briskness. The TR content increased up to a certain degree of wither and thereby improved the ‘body’ of the liquor. Very hard wither, accompanied by a large reduction in moisture content, restricts PPO activity. It appears that in the fresh leaf, high moisture levels together with dissolved oxygen accelerate the enzymic oxidation and produce large amounts of TF. Senescence of the leaf seems to facilitate the production of TR.

Storage deterioration in Central African tea: Changes in chemical composition, sensory characteristics and price evaluation

AbstractLevels of thearubigins (TR), the high‐molecular‐weight SII TR fraction, and caffeine increased during storage, while flavanols and soluble solids decreased. The theaflavin (TF) content, except for an initial increase during the brief maturation period, decreased as a linear function of time during a 5 month storage period. The loss of FT was the major factor responsible for the deterioration in quality and the reduction in evaluation of black tea. Commercial consignments of tea lost an average of 3.6 FT units and over 12% in price over a transit/storage period of 6 months. Oxidative enzyme activity was retained in the manufactured tea. Peroxidase activity was regenerated continuously throughout the period of study, but residual polyphenol oxidase activity decreased during the latter stages of storage.

Biological and chemical factors affecting the valuation of North East Indian plains teas. III. Statistical Evaluation of the Biochemical Constituents and their Effects on Colour, Brightness and Strength of Black Teas

AbstractRegardless of tasters and methods of manufacture five biochemical factors, total oxygen uptake of unprocessed tea shoots and theaflavins (TF), thearubigins (TR), (−)‐epigallocatechin gallate (EGCE) and theogallin (TG), of black tea are the main contributing factors of colour of North East India plains tea. Similarly, three constituents, TF, TR and (−)‐epicatechin gallate (ECG) of black tea, are main the factors for brightness. Four factors, total oxygen uptake and ECG of unprocessed tea shoots and TF and moisture of black tea are the main contributing factors of strength of North East Indian plains tea.