| effects of black tea consumption on plasma catechins and markers of oxidative stress and inflammation in patients with coronary artery disease. | we previously demonstrated that black tea consumption reverses endothelial dysfunction in patients with coronary artery disease. to investigate potential mechanisms of this effect, we examined plasma catechins and systemic markers of oxidation, inflammation, and antioxidant protection from 66 subjects enrolled in that study. we collected samples at baseline, 2 h after 450 ml of black tea (acute), after 4 weeks of 900 ml of black tea per day (chronic), and after acute and chronic consumption of w ... | 2005 | 15649652 |
| the perceived effect of various foods and beverages on stool consistency. | some people believe that chocolate and other foods or beverages may cause constipation. this study was undertaken to quantify the effect of potentially constipating foods and beverages on apparently healthy and constipated populations of german individuals. | 2005 | 15647650 |
| diet-derived phenols in plasma and tissues and their implications for health. | this paper seeks to catalyse a reappraisal of the nature, fate and biological significance in humans of phenols, polyphenols and tannins (ppt) consumed in normal diets, and in particular questions the primacy of ppt radical-scavenging mechanisms for the supposed health benefits of diets rich in fruits and vegetables. ppt are classified by structure and function. arguments are presented to show that cinnamates and derived polyphenols make significantly larger contributions to the total ppt intake ... | 2004 | 15643541 |
| acute effects of tea on fasting and postprandial vascular function and blood pressure in humans. | effects of regular exposure to polyphenolic compounds found in tea, leading to improved endothelial function and blood pressure, may reduce cardiovascular disease risk. controlled trials in humans have found that ingestion of tea can improve endothelial function, but also cause a rapid onset acute increase in blood pressure. | 2005 | 15643124 |
| consumption of both black tea and green tea results in an increase in the excretion of hippuric acid into urine. | a major portion of the catechins in green tea is not absorbed in the small intestine. bacteria in the colon convert nonabsorbed catechins into simpler phenolic compounds, which may also be absorbed. during the production of black tea, most catechins are polymerized to complex molecules called thearubigins. little is known about the microbial degradation of these complex polyphenols, but hippuric acid has been identified as a major excretion product associated with black tea consumption. | 2005 | 15640488 |
| polyphenols in foods are more complex than often thought. | dietary polyphenols show a great diversity of structures, ranging from rather simple molecules (monomers and oligomers) to polymers. higher-molecular-weight structures (with molecular weights of > 500) are usually designated as tannins, which refers to their ability to interact with proteins. among them, condensed tannins (proanthocyanidins) are particularly important because of their wide distribution in plants and their contributions to major food qualities. all phenolic compounds are highly u ... | 2005 | 15640485 |
| antioxidant and lipid lowering activities of indian black tea. | indian black tea; ctc leaf and dust, produced by tata tea limited, kolkata, (india) was studiedin vitro as potential scavenger of oxygen free radicals. super oxide anions were generated in a system containing xanthine-xanthine oxidase (enzymic system) and by nadh- phenozine methosulphate (non enzymic system). anions were assayed in terms of uric acid formation and reduction of nitroblue tetrazolium salt, which were shown to be suppressed by tea extracts. extracts from both leaf and dust also inh ... | 2005 | 23105515 |
| dietary patterns and risk of gastric cancer: a case-control study in uruguay. | gastric cancer is a frequent malignancy in the uruguayan population. in northern counties, incidence rates reach high figures (age-standardized rates [asr], 37.3 per 100,000 men and 18.3 per 100,000 women). diet is a major determinant in gastric carcinogenesis. because foods or food groups have the advantage over nutrients in being most directly related to dietary recommendations, we decided to conduct a case-control study on the relationships between food groups and risk of gastric cancer. for ... | 2004 | 15616769 |
| salivary proteins interact with dietary constituents to modulate tooth staining. | dietary components rich in polyphenols-for example, tea and red wine-are thought to cause tooth staining. in the present study, hydroxyapatite was used as a model of enamel for study of the influence of salivary proteins on the binding of different polyphenols to hydroxyapatite in vitro. neither salivary protein pellicles nor salivary proteins in solution significantly altered the binding of the small polyphenol epigallocatechin to hydroxyapatite. however, hydroxyapatite binding of anthocyanin, ... | 2005 | 15615880 |
| polycyclic aromatic hydrocarbons: pollution and source analysis of a black tea. | investigations into the manufacturing process of one kind of black tea revealed that it included five steps: withering, rolling, fermentation, drying, and drying and sorting. a total of 16 polycyclic aromatic hydrocarbons (pahs) were simultaneously measured in fresh leaves, withered leaves, rolled leaves, fermented leaves, crude black tea, and black tea sampled after each manufacturing stage and in the indoor and outdoor air of the drying house. it was observed that the total contents of the 16 ... | 2004 | 15612828 |
| effects of pu-erh tea on oxidative damage and nitric oxide scavenging. | the effects of pu-erh tea, which is prepared by fermentation of tea, on oxidative damage and nitric oxide scavenging, compared with various other brands of tea were investigated. the total antioxidant activity was determined using the trolox equivalent antioxidant capacity (teac) assay. the results showed that teac values of the 200 microg/ml water extracts of pu-erh tea (wept), green tea, oolong tea, and black tea were 86.3, 85.3, 87.4, and 80.3 (microg/ml), respectively, indicating that wept s ... | 2004 | 15612813 |
| aba associated biochemical changes during somatic embryo development in camellia sinensis (l.) o. kuntze. | the effect of aba on reserve accumulation in maturing somatic embryos of tea was compared with and without aba treatment. changes in the levels of starch, total soluble sugars (tss), proteins, and phenols were studied in the somatic embryos at different stages of development (globular, heart, torpedo and germinating embryos) in order to investigate whether aba could trigger accumulation of storage reserves and thereby overcome the problem of poor germination. after aba treatment (5.0 mg l(-1)) f ... | 2004 | 15602818 |
| on-line high-performance liquid chromatography analysis of the antioxidant activity of phenolic compounds in green and black tea. | teas represent a rich source of dietary antioxidants. this paper describes analysis of the antioxidant potential of individual tea phenolics using an on-line high-performance liquid chromatography (hplc) method. tea phenolics from kenyan green and black teas were identified using liquid chromatography--mass spectrometry (lc-ms(n)) in conjunction with the analysis of their 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (abts+) radical scavenging ability. antioxidant potential of flavan-3-o ... | 2005 | 15602765 |
| polyphenols and antioxidant capacity of bulgarian medicinal plants. | extracts of 21 plants used in bulgarian phytotherapy for the treatment of respiratory, gastrointestinal and other inflammatory disorders were screened in vitro for antioxidant activity and phenolic compounds content. plant extracts were prepared as herbal teas following the ethnic use. the water-phase teac (trolox equivalent antioxidant capacity) of the teas were compared to that of the famous tea-like beverages mate, rooibos and honeybush, and to that of green and black tea, well known for thei ... | 2005 | 15588663 |
| bioavailability and antioxidant activity of tea flavanols after consumption of green tea, black tea, or a green tea extract supplement. | green and black tea polyphenols have been extensively studied as cancer chemopreventive agents. many in vitro experiments have supported their strong antioxidant activity. additional in vivo studies are needed to examine the pharmacokinetic relation of absorption and antioxidant activity of tea polyphenols administered in the form of green or black tea or tea extract supplements. | 2004 | 15585768 |
| concentrations and health risk of polycyclic aromatic hydrocarbons in tea. | sixteen polycyclic aromatic hydrocarbons (pahs) were simultaneously measured in 8 brands of tea and in infusions of one brand of black tea. it was observed that the total contents of the 16 pahs (summation pahs) in the tea samples ranged from 323 to 8800 microg/kg with the highest summation pahs found in a black tea. pahs (3-4 rings) were dominant in all tea samples, with a contribution of 77.7-98.7% of the summation pahs. infusion times from 10 to 120 min were studied during which 3.03-7.69% of ... | 2005 | 15582194 |
| ellipsometry analysis of the in vitro adsorption of tea polyphenols onto salivary pellicles. | the adsorption of components from black tea and of purified tea polyphenols onto a whole unstimulated salivary pellicle-like protein layer, formed in vitro on hydroxyapatite discs, was studied by in situ ellipsometry. it was found that components from black tea and the purified polyphenols epicatechin-3-gallate (ecg), epigallocatechin-3-gallate (egcg) and theaflavin readily adsorbed onto the pellicle. further investigations showed that under the experimental conditions of this study, no black te ... | 2004 | 15560834 |
| clinical study to compare the effectiveness of a test whitening toothpaste with a commercial whitening toothpaste at inhibiting dental stain. | a single centre, randomised single-blind, three-way crossover study was performed, to compare the effect of an experimental test toothpaste with a commercially available whitening toothpaste and water control at inhibiting extrinsic stain promoted by repeated chlorhexidine/tea rinses. | 2004 | 15560810 |
| [a study on the association between tea consumption and stroke]. | the aim of the study was to investigate the association between tea consumption and stroke. | 2004 | 15555387 |
| dietary habits and lung cancer risk among non-smoking women. | a case-control study was conducted to investigate the relationship between diet and the risk of lung cancer among women non-smokers and to compare with women smokers in the same population. data collected by personal interviews from 435 microscopically confirmed cases and 1710 controls were analysed using unconditional logistic regression. in addition to results for all study subjects, associations between diet and lung cancer risk were compared between two highly contrasting groups: smokers (od ... | 2004 | 15548939 |
| will green tea be even better than black tea to increase coronary flow velocity reserve? | | 2004 | 15518633 |
| antioxidant activity of plant extracts on the inhibition of citral off-odor formation. | grape seed, pomegranate seed, green tea, and black tea extracts were used to inhibit the off-odor from citral degradation. a 0.1 m citrate buffer (ph 3), containing 100 ppm citral and 200 ppm gallic acid equivalent plant extract, was incubated at 40 degrees c. the reaction mixtures were analyzed by high-performance liquid chromatography (hplc) at days 0, 6, 10, 13, and 16 to monitor degradation of citral and formation of alpha, p-dimethylstyrene, p-cymene-8-ol, and p-methylacetophenone. the addi ... | 2004 | 15497182 |
| theaflavin, a black tea extract, is a novel anti-inflammatory compound. | tea has been around for centuries, and its medicinal properties have been purported in the literature but never fully confirmed. interleukin-8 is a principle neutrophil chemoattractant and activator in humans. we determined the effects of theaflavin, a black tea-derived polyphenol, on tumor necrosis factor-alpha-mediated expression of the interleukin-8 gene in a549 cells. | 2004 | 15483420 |
| chemical forms of aluminum in xylem sap of tea plants (camellia sinensis l.). | to identify the chemical forms of aluminum (al) transported from roots to shoots of tea plants (c. sinensis l.), 27al-nuclear magnetic resonance and 19f nmr spectroscopy were used to analyze xylem sap. the concentration of al in collected xylem sap was 0.29 mm, twice as high as that of f. catechins were not detected in xylem sap. the concentration of malic acid in xylem sap was higher than that of citric acid, whereas the concentration of oxalic acid was negligible. there were two signals in the ... | 2004 | 15474563 |
| is green tea better than black tea in reducing atherosclerosis? | | 2004 | 15451816 |
| fluorides in groundwater, soil and infused black tea and the occurrence of dental fluorosis among school children of the gaza strip. | the purpose of this study was to determine the fluoride levels in water, soil and tea, and to identify the major fluoride minerals in soil that supply water with fluoride ions. another aim was to study the prevalence of dental fluorosis in permanent dentition of the school children of the gaza strip. monitoring of fluoride levels in 73 groundwater wells and 20 topsoil samples for the last three years revealed a general trend of increasing from north to south of the gaza strip. a linear regressio ... | 2004 | 15384727 |
| octadecyl silica membrane disks modified with a new schiff's base for the preconcentration of lead and copper before their determination in water samples. | a simple and fast method for the extraction and determination of ppt level of pb2+ and cu2+ ions using octadecyl-bonded silica membrane disks modified by a new tetradentates schiffs base [bis(2,4-dimethoxy benzaldehyde) ethylen diimine](tdsb) and inductively coupled plasma atomic emission spectrometry is described. extraction efficiency, and influence of flow rate, ph, type and the least amount of acid for stripping of cu2+ and pb2+ from the modified disks and break through volume were evaluated ... | 2016 | 15279104 |
| analysis of catechin content of commercial green tea products. | tea (camellia sinensis) contains numerous polyphenolic flavonoid-derived compounds known as catechins, which have shown interesting protective activity against cancer and cardiovascular disease. numerous products based on tea are commercially available, many of which claim to contain specific amounts of the bioactive catechins. the catechin content of seven commercial green tea products (encapsulated extracts or tea bags) was quantified by hplc and, where possible, compared to that claimed on th ... | 2003 | 15277054 |
| lung cancer risk among nonsmoking women in relation to diet and physical activity. | to investigate the relationship between diet, physical activity, and the risk of lung cancer among female nonsmokers, and to compare it with female smokers in the same population, we conducted a case-control study. data collected by personal interviews from 419 cases and 1593 controls were analyzed using unconditional logistic regression. as expected, among 130 nonsmoking cases, adenocarcinoma was the predominant cell type (49.2%), followed by squamous cell (20.2%) and small cell cancers (10.5%) ... | 2004 | 15190423 |
| black tea increases coronary flow velocity reserve in healthy male subjects. | epidemiologic studies suggest that tea consumption decreases the risk for cardiovascular events. however, there has been no clinical report examining the effects of tea consumption on coronary circulation. the purpose of this study was to evaluate the effects of black tea on coronary flow velocity reserve (cfvr) using transthoracic doppler echocardiography (ttde). this was a double-blind crossover study of 10 healthy male volunteers conducted to compare the effects of black tea and caffeine on c ... | 2004 | 15165919 |
| [hepatotoxicity due to camelia sinensis]. | | 2004 | 15153351 |
| hplc-msn analysis of phenolic compounds and purine alkaloids in green and black tea. | tea is a complex mixture containing a range of compounds from simple phenolics to complex thearubigins, many of which have well-recognized antioxidant properties. this paper describes the application of high-performance liquid chromatography-mass spectrometry (hplc-ms(n)) methods for the rapid and routine analysis of more than 30 phenolics in tea. green and black tea infusions were injected directly onto a reversed phase hplc column, and the phenolics eluted using two different mobile phase grad ... | 2004 | 15137818 |
| pigments in green tea leaves (camellia sinensis) suppress transformation of the aryl hydrocarbon receptor induced by dioxin. | environmental contaminants such as dioxins enter the body mainly through diet and cause various toxicities through transformation of the aryl hydrocarbon receptor (ahr). we previously reported that certain natural flavonoids at the dietary level suppress the ahr transformation induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd). in this study, we identified lutein and chlorophyll a and b from green tea leaves as the novel antagonists for ahr. these active compounds suppressed ahr transformatio ... | 2004 | 15113147 |
| analysis of theaflavins and thearubigins from black tea extract by maldi-tof mass spectrometry. | black tea contains two major groups of pigments, theaflavins (tfs) and thearubigins (trs). tfs contain a bis-flavan substituted 1,2-dihydroxy-3,4-benzotropolone moiety. unlike the tfs, trs have not yet been characterized. the chemical structure of the trs remains a mystery. the present paper reports our effort to study the structure of tfs and trs using delayed pulsed ion extraction of ions generated via the matrix-assisted laser desorption ionization (maldi) technique, on line with a linear tim ... | 2004 | 15113141 |
| modulation of tea and tea polyphenols on benzo(a)pyrene-induced dna damage in chang liver cells. | the protective effects of three tea extracts (green tea, gte; oolong tea, ote; and black tea, bte) and five tea polyphenols (epicatechin, ec; epicatechin gallate, ecg; epigallocatechin, egc; epigallocatechin gallate, egcg; and theaflavins, thfs) on benzo[a]pyrene (b[a]p)-induced dna damage in chang liver cells were evaluated using the comet assay. b[a]p-induced dna damage in chang liver cells was significantly (p < 0.05) inhibited by gte and ote at a concentration of 10 microg/ml and by bte at 2 ... | 2004 | 15104213 |
| effects of sweet and bitter gustatory stimuli in anorexia nervosa on eeg frequency spectra. | the possible differences in processing gustatory stimuli in anorexic patients compared to healthy control subjects was investigated by electrophysiological methods. the electroencephalogram (eeg) was recorded in outpatients treated with anorexia nervosa (an) and age-matched controls after exposure to sweet (milk chocolate) and bitter (black tea) taste stimuli. power spectrum analysis was performed on eeg epochs recorded in the above conditions. compared to controls a significantly higher percent ... | 2004 | 15094251 |
| development of methods to enhance extrinsic tooth discoloration for comparison of toothpastes. 2. two-product clinical study. | extrinsic staining of teeth is considered to be unsightly and a number of 'whitening' toothpastes have been formulated to inhibit or remove such tooth discoloration. the aim of this study was to compare the stain prevention of two toothpastes. | 2004 | 15058367 |
| determination of ni (ii) in beverages without any sample pretreatment by adsorptive stripping chronopotentiometry (adscp). | the purpose of this paper was to use adsorptive stripping chronopotentiometry for the determination of ni (ii) in worldwide consumed beverages without any sample pretreatment, using dimethilglyoxime (dmg) as complexing agent and a glassy carbon mercury film electrode as the working electrode. ni (dmg)2 complex is adsorbed onto the mercury film at an electrolysis potential of -500 mv for 60 s and then reduced by a -5 microa constant cathodic current. the sensitivity of the method was studied for ... | 2004 | 15053517 |
| reaction of iron(iii) with theaflavin: complexation and oxidative products. | theaflavins are a family of compounds, whose chemistry has been sparsely investigated. they can comprise up to 40% the dry weight of black tea. they are known to chelate metals, however very little knowledge exists on the mechanisms involved. there is some correlation between both of these areas in that following degradation of the iron theaflavin complex, subsequent redox reactions may lead to the formation of similar products on both occasions. the interaction of iron(iii) with theaflavin at p ... | 2004 | 15041246 |
| [determination of low-level pesticide residues in agricultural products by ion-trap gc/ms/ms]. | the objective of this study was to elucidate the utility of ion-trap gc/ms/ms for the analysis of pesticides in extracted matrices from various agricultural products. identification and quantitative analysis of pesticides in matrices were performed by quadrupole gc/ms and ion-trap gc/ms/ms. chlorpyrifos was added to the matrix of spinach, soybean in the pod or corn, and aldrin, dieldrin, endrin, alpha-bhc, beta-bhc, gamma-bhc, delta-bhc, p,p'-ddd, p,p'-dde, o,p'-ddt and p,p'-ddt were added to ea ... | 2003 | 15038113 |
| a clinical study to assess the ability of a powered toothbrush to remove chlorhexidine/tea dental stain. | a single-center, single-blind, two-way crossover study was performed to compare the effects of an electric powered toothbrush with a conventional manual toothbrush at removing chlorhexidine/tea tooth staining. | 2004 | 15016033 |
| role of hydrogen peroxide in bactericidal action of catechin. | catechin (epicatechin (ec), epicatechin gallate (ecg), epigallocatechin (egc) and epigallocatechin gallate (egcg)), which occur in green tea and black tea, possess strong bactericidal action. we observed a reactive oxygen species that was generated from the catechins as the active mechanism: and this reactive oxygen was identified. egcg reacted with the dissolved oxygen in aqueous solution, resulting in the generation of hydrogen peroxide. hydrogen peroxide production derived from egcg rose with ... | 2004 | 14993788 |
| caffeine synthase and related methyltransferases in plants. | caffeine (1,3,7-trimethylxanthine) is a purine alkaloid present in high concentrations in tea and coffee and it is also found in a number of beverages such as coca cola. it is necessary to elucidate the caffeine biosynthetic pathway and to clone the genes related to the production of caffeine not only to determine the metabolism of the purine alkaloid but also to control the content of caffeine in tea and coffee. the available data support the operation of a xanthosine-->7-methylxanthosine-->7-m ... | 2004 | 14977590 |
| effect of a 4-month tea intervention on oxidative dna damage among heavy smokers: role of glutathione s-transferase genotypes. | glutathione s-transferase (gst), a member of the phase ii group of xenobiotic metabolizing enzymes, has been intensively studied at the levels of phenotype and genotype. the gst mu 1 (gstm1) and gst theta 1 (gstt1) genes have a null-allele variant in which the entire gene is absent. the null genotype for both enzymes has been associated with many different types of tumors. the aim of this study was to determine the possible differences in increased oxidative stress susceptibility to smoking with ... | 2004 | 14973088 |
| fluoride and aluminum in teas and tea-based beverages. | to evaluate fluoride and aluminum concentration in herbal, black, ready-to-drink, and imported teas available in brazil considering the risks fluoride and aluminum pose to oral and general health, respectively. | 2004 | 14963548 |
| [acute hepatitis due to exolise, a camellia sinensis-derived drug]. | | 2003 | 14770123 |
| comparative study of the growth-inhibitory and apoptosis-inducing activities of black tea theaflavins and green tea catechin on murine myeloid leukemia cells. | among the black tea polyphenols, theaflavins are generally considered to be the more effective components for the inhibition of carcinogenesis. in this study, we attempted to compare the growth-inhibitory and apoptosis-inducing activities of the four black tea theaflavins (tf-1, tf-2a, tf-2b and tf-3) with the major green tea catechin epigallocatechin-3-gallate (egcg) on the murine myeloid leukemia wehi-3b jcs cells. all the four black tea theaflavins were shown to exert potent anti-proliferativ ... | 2004 | 14767581 |
| delivery of tea polyphenols to the oral cavity by green tea leaves and black tea extract. | catechins and theaflavins, polyphenolic compounds derived from tea (camellia sinensis, fam. theaceae), have been reported to have a wide range of biological activities including prevention of tooth decay and oral cancer. the present study was undertaken to determine the usefulness of green tea leaves and black tea extract for the delivery of catechins and theaflavins to the oral cavity. after holding either green tea leaves (2 g) or brewed black tea (2 g of black tea leaves in 100 ml) in the mou ... | 2004 | 14744744 |
| tissue distribution and intracellular localization of catechins in tea leaves. | we investigated the leaf tissue and cellular morphology of tea (camellia sinensis). osmiophilic material, presumably catechins, was present in mesophyll cells, but not in epidermal cells. electron microscopy showed that catechins were localized to restricted regions within the central vacuoles. in addition, two kinds of small vacuoles of 0.5-3 microm were present in mesophyll cells. one vacuole had catechins within its whole lumen, while the other had an electron-lucent lumen. we found fusion pr ... | 2003 | 14730155 |
| production of hydrogen peroxide by polyphenols and polyphenol-rich beverages under quasi-physiological conditions. | to investigate the ability of the production of h(2)o(2) by polyphenols, we incubated various phenolic compounds and natural polyphenols under a quasi-physiological ph and temperature (ph 7.4, 37 degrees c), and then measured the formation of h(2)o(2) by the ferrous ion oxidation-xylenol orange assay. pyrocatechol, hydroquinone, pyrogallol, 1,2,4-benzenetriol, and polyphenols such as catechins yielded a significant amount of h(2)o(2). we also examined the effects of a metal chelator, ph, and o(2 ... | 2003 | 14730143 |
| impact of tea drinking on iron status in the uk: a review. | the aims of this review are (1) to evaluate the literature on the likely impact of tea drinking on the iron status of different groups within the uk population and (2) to formulate targeted and evidence based advice on tea drinking in the context of iron nutrition in different groups of people. | 2004 | 14718031 |
| foods and beverages in relation to urothelial cancer: case-control study in japan. | the roles of several foods and beverages in the development of bladder cancer remain unclear. | 2004 | 14678179 |
| antioxidative activities of volatile extracts from green tea, oolong tea, and black tea. | antioxidative activities of volatile extracts from six teas (one green tea, one oolong tea, one roasted green tea, and three black teas) were investigated using an aldehyde/carboxylic acid assay and a conjugated diene assay. the samples were tested at levels of 20, 50, 100, and 200 micrograms/ml of dichloromethane. the results obtained from the two assays were consistent. all extracts except roasted green tea exhibited dose-dependent inhibitory activity in the aldehyde/carboxylic acid assay. a v ... | 2003 | 14640590 |
| cocoa has more phenolic phytochemicals and a higher antioxidant capacity than teas and red wine. | black tea, green tea, red wine, and cocoa are high in phenolic phytochemicals, among which theaflavin, epigallocatechin gallate, resveratrol, and procyanidin, respectively, have been extensively investigated due to their possible role as chemopreventive agents based on their antioxidant capacities. the present study compared the phenolic and flavonoid contents and total antioxidant capacities of cocoa, black tea, green tea, and red wine. cocoa contained much higher levels of total phenolics (611 ... | 2003 | 14640573 |
| inhibition of caffeine biosynthesis in tea (camellia sinensis) and coffee (coffea arabica) plants by ribavirin. | the effects of ribavirin, an inhibitor of inosine-5'-monophosphate (imp) dehydrogenase, on [8-(14)c]inosine metabolism in tea leaves, coffee leaves and coffee fruits were investigated. incorporation of radioactivity from [8-(14)c]inosine into purine alkaloids, such as theobromine and caffeine, guanine residues of rna, and co(2) was reduced by ribavirin, while incorporation into nucleotides, including imp and adenine residues of rna, was increased. the results indicate that inhibition of imp dehy ... | 2003 | 14623114 |
| [liver toxicity of camellia sinensis dried etanolic extract]. | | 2003 | 14622530 |
| effective use of tea to limit dietary iron available to starlings (sturnus vulgaris). | wild-caught starlings (sturnus vulgaris) were fed an iron-enriched diet, with or without supplemental black tea leaves, to determine whether tea-derived tannins would prevent intestinal iron absorption. hepatic biopsies were obtained to determine hepatic iron concentrations by atomic absorption spectroscopy. hepatic iron concentrations increased significantly (p = 0.04) in 21 birds that consumed only the iron-enriched diet for 6 mo but not in the 20 birds that consumed the iron-enriched diet wit ... | 2003 | 14582799 |
| [antioxidant activities of green and black teas determined by the cumene hydroperoxide/hemoglobin.methylene blue method]. | antioxidant activity in tea was measured by the new cumene hydroperoxide/hemoglobin.methylene blue(chp/hb.mb) method developed in our laboratory. using the chp/hb.mb method, we investigated the activities of polyphenols(11 varieties) in order to determine their reactivity on chp. according to the chp/hb.mb method, an increase in the number of hydroxyl groups in polyphenols induced high antioxidant activity. we found that this method was capable of measuring the antioxidant activity of polyphenol ... | 2003 | 14560653 |
| fermentation characteristics of some assamica clones and process optimization of black tea manufacturing. | changes in the specific activities of polyphenol oxidase (ppo), peroxidase (pod), and protease and in the relative amounts of flavan-3-ols for eight genetically derived cultivated teas at various stages of leaf maturity and in four succescive seasons were examined. a series of investigations were carried out to study the cross-reactivity of complex polyphenols and ppo-generated orange-yellow theaflavins, as well as of pod oxidized substrates, producing brown so-called thearubigins during ferment ... | 2003 | 14558781 |
| the epidemiology of tea consumption and colorectal cancer incidence. | this manuscript provides a brief synopsis of 30 studies aimed at examining tea consumption as a factor in the incidence of colon and rectal cancers. the 30 papers examine populations in 12 countries and provide data on consumption of both black and green tea. these studies do not provide consistent evidence to support the theory from animal studies and basic research that tea is a potent chemopreventive agent. details of the studies are presented, and the potential impact of measurement error, p ... | 2003 | 14519831 |
| effect of increased tea consumption on oxidative dna damage among smokers: a randomized controlled study. | tea drinking has been associated with decreased occurrence of cancer and heart disease. one potential mechanism for these findings is the strong antioxidant effect of tea polyphenols. a phase ii randomized controlled tea intervention trial was designed to study the effect of high consumption (4 cups/d) of decaffeinated green or black tea on oxidative dna damage as measured by urinary 8-hydroxydeoxyguanosine (8-ohdg) among smokers over a 4-mo period. a total of 143 heavy smokers, aged 18-79 y, we ... | 2003 | 14519830 |
| black tea consumption reduces total and ldl cholesterol in mildly hypercholesterolemic adults. | despite epidemiological evidence that tea consumption is associated with the reduced risk of coronary heart disease, experimental studies designed to show that tea affects oxidative stress or blood cholesterol concentration have been unsuccessful. we assessed the effects of black tea consumption on lipid and lipoprotein concentrations in mildly hypercholesterolemic adults. tea and other beverages were included in a carefully controlled weight-maintaining diet. five servings/d of tea were compare ... | 2003 | 14519829 |
| antioxidant activity of tea polyphenols in vivo: evidence from animal studies. | tea is particularly rich in polyphenols, including catechins, theaflavins and thearubigins, which are thought to contribute to the health benefits of tea. tea polyphenols act as antioxidants in vitro by scavenging reactive oxygen and nitrogen species and chelating redox-active transition metal ions. they may also function indirectly as antioxidants through 1) inhibition of the redox-sensitive transcription factors, nuclear factor-kappab and activator protein-1; 2) inhibition of "pro-oxidant" enz ... | 2003 | 14519826 |
| coordination of aluminium with purpurogallin and theaflavin digallate. | polyphenols are antioxidants, which are known to influence bioavailability of metals in the body. the theaflavins of black tea are important members of this family, which have been sparsely investigated. the complexation of aluminium with purpurogallin (2,3,4,6-tetrahydroxy-5h-benzocyclohepten-5-one) has been investigated using nuclear magnetic resonance (nmr) spectroscopy, liquid chromatography-mass spectroscopy (lc-ms) and fourier transform infrared (ft-ir) spectroscopy. 1h nmr was used to det ... | 2003 | 13678812 |
| hydroxyl radical and hypochlorous acid scavenging activity of small centaury (centaurium erythraea) infusion. a comparative study with green tea (camellia sinensis). | small centaury (centaurium erythraea rafin.) is a herbal species with a long use in traditional medicine due to its digestive, stomachic, tonic, depurative, sedative and antipyretic properties. this species is reported to contain considerable amounts of polyphenolic compounds, namely xanthones and phenolic acids as the main constituents. although the antiradicalar activity of some pure polyphenolic compounds is already known, it remains unclear how a complex mixture obtained from plant extracts ... | 2003 | 13678237 |
| adsorption from black tea and red wine onto in vitro salivary pellicles studied by ellipsometry. | the adsorption of black tea and red wine components onto a pellicle-like protein layer formed in vitro by adsorption from whole unstimulated saliva on hydroxyapatite discs were studied by in situ ellipsometry. it was found that components from black tea readily adsorbed to the pellicle. subsequent exposure to saliva led to further adsorption of salivary components to give an overall increase in the amounts adsorbed. the amounts adsorbed increased still further following a third tea and saliva ex ... | 2003 | 12974686 |
| identification of chlorophylls and carotenoids in major teas by high-performance liquid chromatography with photodiode array detection. | the separation and identification of pigments, chlorophylls, and carotenoids of seven teas and fresh leaf of tea (camellia sinensis) by high-performance liquid chromatography (hplc) are described. hplc was carried out using a symmetry c(8) column with a photodiode array detector. pigments were eluted with a binary gradient of aqueous pyridine solution at a flow rate of 1.0 ml/min at 25 degrees c. hplc analyses achieved the separation of more than 100 pigment peaks, and 79 pigment species, 41 chl ... | 2003 | 12926875 |
| lack of association between tea and cardiovascular disease in college alumni. | epidemiological studies suggest that tea intake, a major dietary source of flavonoids, may be associated with a decreased risk of cardiovascular disease (cvd). | 2003 | 12913023 |
| aluminium and fluoride concentrations of three tea varieties growing at lantau island, hong kong. | the present project aims to investigate aluminium (al) and fluoride (f) contents in teas (camellia sinensis (l.) o. kuntze). three different commercial tea varieties: assam variety and two china sub-varieties, a large leafed variety and small leafed variety, were collected in two tea gardens of lantau island tea plantation of hong kong. in general, high concentrations of al and f were accumulated in the mature leaves (15.3 and of 2.07 g kg-1 respectively). among the three varieties, 'the small l ... | 2003 | 12901167 |
| black tea extract supplementation decreases oxidative damage in jurkat t cells. | the purpose of this study was to investigate the protective effect of black tea (bt) extract against induced oxidative damage in jurkat t-cell line. cells supplemented with 10 or 25 mg/l bt were subjected to oxidation with ferrous ions. malondialdehyde (mda) production as marker of lipid peroxidation, dna single strand breaks as marker of dna damage, and modification of the antioxidant enzyme activity, glutathione peroxidase (gpx) were measured. results show the efficacy of bt polyphenols to dec ... | 2003 | 12893297 |
| catechin content of 18 teas and a green tea extract supplement correlates with the antioxidant capacity. | our literature review of currently available data in the area of tea and cancer prevention demonstrated that there is more conclusive evidence for the chemopreventive effect of green tea compared with black tea. we suggest that this is due to a large variation of the flavanol content in tea, which is not taken into consideration in most of the epidemiological studies. it was the purpose of this study to determine the flavanol content of various teas and tea products and to correlate it with thei ... | 2003 | 12881018 |
| black tea consumption and risk of rectal cancer in moscow population. | this population-based case-control study (663 cases and 323 controls) examined the effect of black tea intake on the risk of rectal cancer in moscow residents. the moscow population was selected for its wide range of black tea consumption. | 2003 | 12875797 |
| potential therapeutic properties of green tea polyphenols in parkinson's disease. | tea is one of the most frequently consumed beverages in the world. it is rich in polyphenols, a group of compounds that exhibit numerous biochemical activities. green tea is not fermented and contains more catechins than black tea or oolong tea. although clinical evidence is still limited, the circumstantial data from several recent studies suggest that green tea polyphenols may promote health and reduce disease occurrence, and possibly protect against parkinson's disease and other neurodegenera ... | 2003 | 12875608 |
| green tea and risk of breast cancer in asian americans. | there is substantial in vitro and in vivo evidence implicating tea polyphenols as chemopreventive agents against various cancers. however, epidemiologic data obtained from mainly western populations are not supportive of a protective role of tea, mainly black tea, in the etiology of breast cancer. much less is known about the relationship between green tea and breast cancer risk. during 1995-1998, we conducted a population-based, case-control study of breast cancer among chinese, japanese and fi ... | 2003 | 12845655 |
| beta-glycosylamidine as a ligand for affinity chromatography tailored to the glycon substrate specificity of beta-glycosidases. | an affinity adsorbent for beta-glycosidases has been prepared by using beta-glycosylamidine as a ligand. beta-glucosylamidine and beta-galactosylamidine, highly potent and selective inhibitors of beta-glucosidases and beta-galactosidases, respectively, were immobilized by a novel one-pot procedure involving the addition of a beta-glycosylamine and 2-iminothiolane.hcl simultaneously to a matrix modified with maleimido groups via an appropriate spacer to give an affinity adsorbent for beta-glucosi ... | 2003 | 12829393 |
| thearubigin, the major polyphenol of black tea, ameliorates mucosal injury in trinitrobenzene sulfonic acid-induced colitis. | inflammatory bowel disease is characterized by oxidative and nitrosative stress, leukocyte infiltration and upregulation of proinflammatory cytokines. the aim of the present study was to examine the protective effects of thearubigin, an anti-inflammatory and anti-oxidant beverage derivative, on 2,4,6-trinitrobenzene sulfonic acid (tnbs)-induced colitis in mice, a model for inflammatory bowel disease. intestinal lesions (judged by macroscopic and histological score) were associated with neutrophi ... | 2003 | 12787838 |
| chlorogenic acid, quercetin-3-rutinoside and black tea phenols are extensively metabolized in humans. | dietary phenols are antioxidants, and their consumption might contribute to the prevention of cardiovascular disease. coffee and tea are major dietary sources of phenols. dietary phenols are metabolized extensively in the body. lack of quantitative data on their metabolites hinders a proper evaluation of the potential biological effects of dietary phenols in vivo. the aim of this study was to identify and quantify the phenolic acid metabolites of chlorogenic acid (major phenol in coffee), querce ... | 2003 | 12771321 |
| carbon-13 cp-mas nuclear magnetic resonance studies of teas. | 13c cp-mas nmr spectra of green and black tea were obtained and assigned based on the solid-state nmr spectra of tropolone, (+)-catechin hydrate, gallic acid, caffeine and flavone derivatives. the peak shape and chemical shifts observed for carbonyl carbons in cp-mas spectra of teas indicate the existence of different chemical species, mainly free phenollic acids and ester derivatives of flavonoids. the peak patterns allow to establish differences between both teas. | 2003 | 12763559 |
| black tea extract and dental caries formation in hamsters. | several studies have suggested that green tea and oolong tea extracts have antibacterial and anticariogenic properties in vitro and in vivo. the aim of the present study was to determine the effect of a standardized black tea extract (bte) on caries formation in inbred hamsters on a regular and a cariogenic diet. eighty hamsters were divided into four groups of 20 animals each. two groups received a pelleted regular diet (labchow) with water or bte ad libitum. the other two groups received a pow ... | 2003 | 12701240 |
| can black tea influence plasma total homocysteine concentrations? | polyphenols can act as acceptors of methyl groups during the metabolism of methionine to homocysteine. this may result in elevations in plasma total homocysteine (thcy) concentrations after ingestion of polyphenol-rich beverages such as tea. | 2003 | 12663290 |
| factors affecting the levels of tea polyphenols and caffeine in tea leaves. | an isocratic hplc procedure was developed for the simultaneous determination of caffeine and six catechins in tea samples. when 31 commercial teas extracted by boiling water or 75% ethanol were analyzed by hplc, the levels of (-)-epigallocatechin 3-gallate (egcg), and total catechins in teas were in the order green tea (old leaves) > green tea (young leaves) and oolong tea > black tea and pu-erh tea. tea samples extracted by 75% ethanol could yield higher levels of egcg and total catechins. the ... | 2003 | 12643643 |
| studies with black tea and its constituents on leukemic cells and cell lines. | the anticancer effect of black tea (bt) and its polyphenols theaflavin (tf) and thearubigin (tr) has been evaluated on u-937 cell line, a myeloid leukemic cell line and on leukemic cells isolated from peripheral blood of chronic myeloid leukemia (cml) patients. in both types of cells, cell growth inhibition was observed 24 hrs after treatment with bt, tf and tr. mtt assay showed growth inhibition of metabolically active cells and inhibition of dna synthesis was observed by 3h-thymidine incorpora ... | 2002 | 12636103 |
| cancer chemopreventive activity and bioavailability of tea and tea polyphenols. | consumption of tea (camellia sinensis) has been associated with many health benefits including the prevention of cancer. based on in vitro experiments, many mechanisms have been proposed to account for the cancer chemopreventive activity. the importance of some of these mechanisms in vivo remains in question due to an incomplete understanding of the bioavailability of the polyphenolic compounds in tea. in this article, the literature on the cancer chemopreventive activity of tea and the tea poly ... | 2013 | 12628518 |
| bioavailability of soluble oxalate from tea and the effect of consuming milk with the tea. | to measure the availability of oxalate normally extracted when making tea from two commercially available black teas bought from a supermarket in christchurch, new zealand in july 2001. | 2003 | 12627177 |
| novel pvc-based copper(ii) membrane sensor based on 2-(1'-(4'-(1''-hydroxy-2''-naphthyl)methyleneamino)butyl iminomethyl)-1-naphthol. | a copper(ii) ion-selective pvc membrane sensor based on 2-(1'-(4'-(1''-hydroxy-2''-naphthyl)methyleneamino)butyl iminomethyl)-1-naphthol (bhnb) as a novel schiff base containing a sensing material has been successfully developed. the sensor exhibits a good linear response of 29 mv per decade within the concentration range of 10(-1)-10(-6) m of cu2+. the sensor shows good selectivity for copper(ii) ion in comparison with alkali, alkaline earth, transition and heavy metal ions. the bhnb-based sens ... | 2003 | 12608749 |
| development of caps markers based on three key genes of the phenylpropanoid pathway in tea, camellia sinensis (l.) o. kuntze, and differentiation between assamica and sinensis varieties. | the genetic diversity of tea, camellia sinensis (l.) o. kuntze, including the two main cultivated sinensis and assamica varieties, was investigated based on pcr-rflp analysis of pal, chs2 and dfr, three key genes involved in catechin and tannin synthesis and directly responsible for tea taste and quality. polymorphisms were of two types: amplicon length polymorphism (alp) due to the presence of indels in two introns of pal and dfr, and point mutations detected after restriction of amplified frag ... | 2003 | 12589537 |
| lifestyle, health and disease prevention: the underlying mechanisms. | international studies in geographic pathology provide background information that a disease may have a quite different incidence and resulting mortality as a function of area of residence. investigations in animals can model fairly precisely what is learned through such international research, and provide the basis for examining relevant hypotheses and, more importantly, possible mechanisms of action. these approaches can yield public health recommendations and health promotion activities. regul ... | 2002 | 12570328 |
| determination of tea polyphenols and caffeine in tea flowers (camellia sinensis) and their hydroxyl radical scavenging and nitric oxide suppressing effects. | the native occurrence of tea polyphenols, namely, (-)-epicatechin, (+)-catechin, (-)-epigallocatechin 3-gallate, (-)-epicatechin, and (-)-epicatechin 3-gallate, and caffeine in tea flowers was assessed by an isocratic hplc procedure. the levels of total catechins and caffeine were determined in tea flowers collected from 10 different species of camellia sinensis. the results showed the levels of total catechin ranged from 10 to 38 mg/g, whereas the level of caffeine ranged from 3 to 8 mg/g. leve ... | 2003 | 12568558 |
| signal transduction pathways: targets for green and black tea polyphenols. | tea is one of the most popular beverages consumed in the world and has been demonstrated to have anti-cancer activity in animal models. research findings suggest that the polyphenolic compounds, (-)-epigallocatechin-3-gallate found primarily in green tea, and theaflavin-3,3'-digallate, a major component of black tea, are the two most effective anti-cancer factors found in tea. several mechanisms to explain the chemopreventive effects of tea have been presented but others and we suggest that tea ... | 2003 | 12542977 |
| black tea represents a major source of dietary phenolics among regular tea drinkers. | 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 fr ... | 2002 | 12516885 |
| prevention of coronary heart disease and cancer by tea, a review. | biomedical research has uncovered the mechanisms whereby tea promotes good health and lowers the risk of major chronic diseases, such as heart disease and many types of cancer. the active components in tea are polyphenols, epigallocatechin gallate in green tea, theaflavins and thearubigins in black tea. green and black tea and the polyphenols have similar beneficial effects. the mechanisms are categorized into 5 groups. 1) tea polyphenols are powerful antioxidants. they decrease the oxidation of ... | 2003 | 21432397 |
| characterization of armillaria isolates from tea (camellia sinensis) in kenya. | armillaria is a primary root rot pathogen of tea (camellia sinensis) in kenya. the main species presently described in this country are a. mellea and a. heimii. a survey covering fourteen districts of kenya was carried out and forty-seven isolates of armillaria collected. cultural morphology, rhizomorph characteristics, somatic incompatibility and features of basidiomata were used to characterize the isolates, together with molecular analysis based on randomly amplified polymorphic dna (rapd), i ... | 2010 | 21156603 |
| oxalate content and calcium binding capacity of tea and herbal teas. | thirty-two commercially available teas consisting of green, oolong and black teas were bought from supermarkets in christchurch, new zealand in june 2001. fifteen herbal teas were also purchased at the same time. the soluble oxalate content of the infusate made from each of the teas was determined using high pressure liquid chromatography. the mean soluble oxalate contents of black tea in tea bags and loose tea leaves were 4.68 and 5.11 mg/g tea, respectively, while green teas and oolong tea had ... | 2002 | 12495262 |
| specific fluctuations in the composition of lipoxygenase- and glycosidase-generated flavors in some cultivated teas of assam. | variations of fatty acid compositions, glycosides precursors, and lipoxygenase and glycosidase enzymatic activities were used simultaneously to differentiate for nine genetically different cultivated teas, four seasonal changes, and the affect of leaf maturity. the muscatel flavor of second-flush teas was associated with increased activities of glycosidase and several terpenes, phenolics, and aliphatic compounds bound to glycosides, whereas high levels of fatty acids and lipoxygenase activity bi ... | 2002 | 12475290 |
| tea consumption and the prevalence of coronary heart disease in saudi adults: results from a saudi national study. | the aim of the study was to determine whether there was a relationship between tea consumption and the prevalence of coronary heart disease (chd) in saudi arabia. | 2003 | 12473426 |
| the association of 137cs with various components of tea leaves fermented from chernobyl contaminated green tea. | the distribution of 137cs among various components of fermented tea leaves harvested after the chernobyl accident was investigated by applying a sequential extraction procedure. an association of the radioisotope with the phenolic moiety of a phenylglucoside was detected in black tea infusate using permeation chromatography as well as uv and nmr spectroscopy. the chemical structure of a 137cs containing compound also isolated from an artificially 137cs labelled aqueous extract of green leaves wa ... | 2002 | 12440515 |
| antioxidative activities of oolong tea. | while the antioxidative properties of green and black tea have been extensively studied, less attention has been given to these properties in oolong tea. the reducing powers, the 2,2-diphenyl-1-picrylhydrazyl (dpph) scavenging activities, the amount of total phenolic compounds, the inhibitory effect on fecl(2)/h(2)o(2) (fenton reaction system)-induced dna damage, and the inhibitory effect on erythrocyte hemolysis of an oolong tea water extract (ote) were evaluated in the present study. the ote w ... | 2002 | 12405799 |
| validation of a food frequency questionnaire in the hiroshima/nagasaki life span study. | we evaluated the performance of a 22-item food frequency questionnaire (ffq) administered in 1980-81 to 3,005 members of the adult health study cohort, part of the life span study. the questionnaire was compared with the records of a 24-hour dietary survey that was performed in 1984-85. from the dietary records, food and nutrient intakes were estimated. the association between the two measures of dietary intake was assessed using mantel-haenszel chi-square test and the spearman's rank correlatio ... | 2002 | 12395883 |
| cryopreservation of tea (camellia sinensis l.) seeds and embryonic axes. | this study investigated the tolerance to desiccation and freezing of tea seeds, embryonic axes (eas) and cotyledonary embryonic axes (ceas, consisting of eas with portions of cotyledons still attached). no seeds germinated after desiccation and cryopreservation. eas extracted from seeds desiccated to 18.9% moisture content (fresh weight basis) and cryopreserved showed 20.7% survival but plantlet production from these eas was impossible. when eas and ceas were extracted from seeds before being su ... | 2004 | 12391481 |
| tea consumption and ovarian cancer risk: a case-control study in china. | to investigate whether tea consumption has an etiological association with ovarian cancer, a case-control study was conducted in china during 1999-2000. the cases were 254 patients with histologically confirmed epithelial ovarian cancer. the 652 controls comprised 340 hospital visitors, 261 non-neoplasm hospital outpatients, and 51 women recruited from the community. information on the frequency, type, and duration of tea consumption was collected by personal interview using a validated question ... | 2002 | 12163323 |