Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| 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 effects of tea: evidence from human clinical trials. | tea remains the most consumed drink in the world after water, well ahead of coffee, beer, wine and carbonated soft drinks. an accumulated number of population studies suggests that consumption of green and black tea beverages may bring positive health effects (1). one hypothesis explaining such effects is that the high levels of flavonoids in tea can protect cells and tissues from oxidative damage by scavenging oxygen-free radicals. chemically, the flavonoids found in green and black tea are ver ... | 2003 | 14519827 |
| 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 |
| mechanisms of cancer prevention by tea constituents. | consumption of tea (camellia sinensis) has been suggested to prevent cancer, heart disease and other diseases. animal studies have shown that tea and tea constituents inhibit carcinogenesis of the skin, lung, oral cavity, esophagus, stomach, liver, prostate and other organs. in some studies, the inhibition correlated with an increase in tumor cell apoptosis and a decrease in cell proliferation. studies with human cancer cell lines have demonstrated that epigallocatechin-3-gallate (egcg), a major ... | 2003 | 14519824 |
| modulation of arsenic induced cytotoxicity by tea. | arsenic, a naturally ocurring chemical element, is considered hazardous to human health. inorganic arsenic compounds were found to induce cytotoxicity in chinese hamster v-79 cells in culture. the arsenite form was more toxic than arsenate. extracts of green and two varieties of black tea, as well as their principal polyphenols, (-)-epigallocatechingallate and theaflavin, efficiently counteracted the cytotoxic effects of arsenic compounds. on the basis of the amount of tea extract that afforded ... | 2003 | 14507244 |
| antimutagenic effects of black tea in the salmonella typhimurium reverse mutation assay. | black tea (camellia sinensis) is one of the most widely consumed beverages worldwide. its chemopreventive effects are well documented in the literature. in the present set of investigations antimutagenic effects of aqueous black tea extract (ate) and black tea polyphenols (btp) were evaluated in the ames test using salmonella typhimurium tester strains ta 98 and ta 100. addition of benzo(a)pyrene (bap) and cyclophosphamide (cp), two well known mutagens, at the concentrations of 20 and 15 microg/ ... | 2003 | 14507238 |
| notes on fungi from north-east india. x. chaetospermum camelliae sp. nov. on tea (camellia sinensis (l.) o. kuntze). | 1962 | 13859604 | |
| 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 |
| [saponins from the seeds of thea sinensis l. iii. the constitution of thea-sapogenol. (1)]. | 1954 | 13215030 | |
| 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 |
| the prevalence of tongue lesions in 5150 turkish dental outpatients. | the aim of this study was to assess the prevalence of nine tongue conditions and relate to data obtained about oral hygiene or habits in turkish dental outpatients. | 2003 | 12974518 |
| chain-breaking antioxidant activity and cyclic voltammetry characterization of polyphenols in a range of green, oolong, and black teas. | a series of eight green, eight oolong, and 17 black teas have been analyzed for polyphenol content by absorbance at 272 nm and cyclic voltammetry response at an inert carbon electrode, a new method developed to provide a rapid measure of easily oxidizable polyphenols in beverages. the chain-breaking antioxidant activity of the teas has also been determined during the chain oxidation of methyl linoleate in a ph 7.4 micellar solution, for which realistic kinetic parameters have been derived. while ... | 2003 | 12952436 |
| thoughts on thearubigins. | the chemistry underlying the changes which occur during tea leaf fermentation is reviewed and used as a basis for proposals for the structure of thearubigins, the major pigments of black teas. | 2003 | 12946406 |
| suppression of fatty acid synthase in mcf-7 breast cancer cells by tea and tea polyphenols: a possible mechanism for their hypolipidemic effects. | tea is a heavily consumed beverage world wide because of its unique aroma, less cost and broad availability. fatty acid synthase (fas) is a key enzyme in lipogenesis. fas is overexpressed in the malignant human breast carcinoma mcf-7 cells and its expression is further enhanced by the epidermal growth factor (egf). the egf-induced expression of fas was inhibited by green and black tea extracts. the expression of fas was also suppressed by the tea polyphenol (-)-epigallocatechin 3-gallate (egcg), ... | 2003 | 12931129 |
| 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 |
| screening of chemopreventive tea polyphenols against pah genotoxicity in breast cancer cells by a xre-luciferase reporter construct. | polycyclic aromatic hydrocarbons (pahs) are established cancer initiators that can be found in our food and environment. some dietary plant polyphenols are strong inhibitors to pah-induced mutagenesis, whereas others may not be as effective. to identify the chemopreventive compounds from a huge volume of dietary components, the development of an efficient screening method is required. in this study, a xenobiotic response element (xre)-luciferase reporter plasmid was constructed to screen for som ... | 2003 | 12925309 |
| 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 |
| black tea prevents cigarette smoke-induced oxidative damage of proteins in guinea pigs. | cigarette smoke (cs) causes oxidative damage and tea polyphenols have strong antioxidant properties. therefore, we studied the effect of a black tea (bt) infusion on cs-induced oxidative damage of proteins both in vitro and in vivo. in the in vitro experiment, bovine serum albumin (bsa) or a guinea pig tissue microsomal suspension was incubated with an aqueous extract of cs (cs-solution) in the presence or absence of the bt infusion. protein oxidation was measured by immunoblotting of the dinitr ... | 2003 | 12888648 |
| 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 |
| tea can protect against aberrant crypt foci formation during azoxymethane induced rat colon carcinogenesis. | tea shows many health promoting activities including chemopreventive action during carcinogenesis due to the presence of antioxidative polyphenolic constituents. the present experiment evaluated the anticarcinogenic role of black tea infusion on azoxymethane induced colonic preneoplastic lesions, the aberrant crypt foci in sprague-dawley rats. rats were injected with azoxymethane (15 mg/kg b.w.) and received oral administration of 1% and 2% (w/v) tea infusions from first day of carcinogen applic ... | 2003 | 12866568 |
| determination of tea components with antioxidant activity. | levels of essential elements with antioxidant activity, as well as catechins, gallic acid, and caffeine levels, in a total of 45 samples of different teas commercialized in spain have been evaluated. chromium, manganese, selenium, and zinc were determined in the samples mineralized with hno(3) and v(2)o(5), using etaas as the analytical technique. the reliability of the procedure was checked by analysis of a certified reference material. large variations in the trace element composition of teas ... | 2003 | 12848521 |
| 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 |
| hepatic and intestinal cytochrome p450 and conjugase activities in rats treated with black tea theafulvins and theaflavins. | theaflavins and theafulvins, a fraction of thearubigins, were isolated from aqueous infusions of black tea, and their effects on the hepatic and intestinal cytochrome p450 system, and on the glutathione s-transferase, epoxide hydrolase, glucuronosyl transferase and sulphotransferase enzyme systems were investigated in rats following oral intake for four weeks. neither theafulvins nor theaflavins influenced cytochrome p450 activity in the liver as exemplified by the o-dealkylations of methoxy-, e ... | 2003 | 12842182 |
| 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 |
| antioxidant activity of a botanical extract preparation of ilex paraguariensis: prevention of dna double-strand breaks in saccharomyces cerevisiae and human low-density lipoprotein oxidation. | we analyzed the antioxidant properties of ilex paraguariensis infusion (ip) popularly known as mate (mä'tā), by using two experimental models: the induction of dna double-strand breaks (dsb) by hydrogen peroxide (h(2)o(2)) and lethality in saccharomyces cerevisiae, as well as peroxide and lipoxygenase-induced human low-density lipoprotein (ldl) oxidation. diploid yeast cells were exposed to different concentrations of h(2)o(2) (5-10 mmol/l) in the absence or presence of ip infusion (10(-1) v/v) ... | 2003 | 12816626 |
| in vitro inhibition of human cytochrome p450-mediated metabolism of marker substrates by natural products. | spices, herbal and black teas, and soybean products were analyzed for their capacity to inhibit in vitro metabolism of drug marker substrates by human cytochrome p-450 (cyp) isoforms. inhibition of drug metabolism was determined using aliquots or infusions from these products in a fluorescence-detection assay. aliquots and infusions of all natural product categories inhibited 3a4 metabolism to some extent. of the 26 aliquots from teas and spices further tested with 2c9, 2c19 and 2d6, many demons ... | 2003 | 12809364 |
| 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 |
| effect of green tea in the prevention and reversal of fasting-induced intestinal mucosal damage. | epidemiologic studies have suggested that high consumption of green tea protects against the development of chronic active gastritis and decreases the risk of stomach cancer. the effect of green tea on the intestinal mucosa was not studied previously, so we examined the effects of green tea on the intestinal mucosa of fasting rats in a controlled experimental setting. | 2003 | 12781855 |
| 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 |
| selective inhibition of adamts-1, -4 and -5 by catechin gallate esters. | three mammalian adamts enzymes, adamts-1, -4 and -5, are known to cleave aggrecan at certain glutamyl bonds and are considered to be largely responsible for cartilage aggrecan catabolism observed during the development of arthritis. we have previously reported that certain catechins, polyphenolic compounds found in highest concentration in green tea (camellia sinensis), are capable of inhibiting cartilage aggrecan breakdown in an in vitro model of cartilage degradation. we have now cloned and ex ... | 2003 | 12755694 |
| influence of tea on intrinsic colour of previously bleached enamel. | aim of the study was to evaluate the influence of tea applied at various time intervals after bleaching of enamel on intrinsic tooth colour. ninety bovine specimens were distributed among six groups (a-f, n=15). the samples of group a-d were bleached with the 10% carbamide peroxide (cp) gel vivastyle for 8 h, followed by storing in artificial saliva for the remaining period of the day. the specimens were removed from the saliva at different intervals (a: 0 min, b: 60 min, c: 240 min) and immerse ... | 2003 | 12752928 |
| [effects of tea on aberrant crypt foci and colorectal tumors in rats]. | the present study was designed to investigate the chemopreventive effects of green tea and tea pigments (the main component of black tea) on 1,2-dimethylhydrazine (dmh)-induced rat colorectal carcinogenesis. compared with the positive control group, green tea and tea pigments groups had less numbers of aberrant crypt foci (acf) (p < 0.01) at the end of week 16. at the end of week 32, all rats in the positive control group developed colorectal tumors with an average of 2.6 tumors per rat, and a m ... | 2000 | 12725046 |
| antidiarrhoeal activity of hot water extract of black tea (camellia sinensis). | the effect of a hot water extract of black tea (camellia sinensis (l.) o. kuntze, theaceae) on upper gastrointestinal transit and on diarrhoea was investigated employing conventional rodent models of diarrhoea. black tea extract was found to possess antidiarrhoeal activity in all the models of diarrhoea used. naloxone (0.5 mg/kg i.p.) significantly inhibited the antidiarrhoeal activity of the extract as well as loperamide, thus indicating a role of the opioid system in the antidiarrhoeal activit ... | 2003 | 12722145 |
| dna degradation by water extract of green tea in the presence of copper ions: implications for anticancer properties. | in recent years a number of reports have documented the chemopreventive effect of green tea consumption on various types of cancers such as those of bladder, prostate, esophagus and stomach. this property is attributed to the presence in green tea of polyphenols known as catechins. these include epigallocatechin-3-gallate, epigallocatechin and epicatechin. in addition to their antioxidant properties plant derived polyphenolics are also capable of oxidative dna damage particularly in the presence ... | 2003 | 12722140 |
| inhibition of cell proliferation and induction of apoptosis during azoxymethane induced colon carcinogenesis by black tea. | tea (camellia sinensis) is one of the most popular beverages, consumed worldwide. the health promoting properties of tea have been attributed to its antioxidative polyphenolic constituents and their oxidative products. the aim of the present study was to evaluate the chemopreventive efficacy of a black tea infusion on azoxymethane induced colonic preneoplastic lesions, the aberrant crypt foci in sprague-dawley rats. rats were injected with azoxymethane (15mg/kg.b.w.) and received oral administra ... | 2002 | 12718607 |
| elimination of deleterious effects of free radicals in murine skin carcinogenesis by black tea infusion, theaflavins & epigallocatechin gallate. | in recent years, numerous reports have been published on the identification of novel, naturally occurring antioxidants from plants, animals, microbial sources and processed food products. most natural antioxidants are phenolic compounds, which have a modulatory role on physiological functions and biotransformation reactions involved in the detoxification process, thereby affording protection from cytotoxic, genotoxic and metabolic actions of environmental toxicants. as part of our program on eva ... | 2002 | 12718579 |
| 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 |
| an anticlastogenic in vivo micronucleus assay for tea. | common use of antimutagens and anticarcinogens in everyday life is an effective measure for preventing human cancer and genetic diseases. antioxidant properties of tea have vast potential as protective agents against diverse toxic effects. the present study was aimed to evaluate the role of aqueous clonal tea extracts (green tea, oolong tea and black tea) in modulating the genotoxic damage induced by cyclophosphamide (cp), a commonly used chemotherapeutic drug and a well-known mutagen and clasto ... | 2002 | 12674376 |
| 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 |
| structures of (-)-epicatechin glucuronide identified from plasma and urine after oral ingestion of (-)-epicatechin: differences between human and rat. | (-)-epicatechin is one of the most potent antioxidants present in the human diet. particularly high levels are found in black tea, apples, and chocolate. high intake of catechins has been associated with reduced risk of cardiovascular diseases. there have been several reports concerning the bioavailability of catechins, however, the chemical structure of (-)-epicatechin metabolites in blood, tissues, and urine remains unclear. in the present study, we purified and elucidated the chemical structu ... | 2003 | 12654472 |
| 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 |
| chain-breaking antioxidant capability of some beverages as determined by the clark electrode technique. | the protective effects of red wine, tea, and coffee on cancer, atheroclerosis, and other diseases are attributed to the antioxidant activity (aoa) of polyphenols, which are abundant in those beverages. we present a rational procedure for determining the total chain-breaking aoa of beverages with the use of the clark electrode technique. the procedure is based on the steady monitoring of oxygen consumption accompanying the chain peroxidation of methyl linoleate in triton x-100 aqueous micelles in ... | 2001 | 12639404 |
| 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 |
| assessment of membrane protection by traditional chinese medicines using a flow cytometric technique: preliminary findings. | in this preliminary study, we used a 'living cell' flow-cytometric approach to membrane protection by four traditional chinese medicines (tcms). cells were incubated, separately, for 30 min with aqueous extracts (1.5% w/v) of lingzhi (ganoderma lucidum), ginger (zingiber officianale), ginseng (panax ginseng), and green tea (camellia sinensis). membranes were labelled with a fluorescent probe, cells were then incubated with cumene hydroperoxide, and site-specific oxidation induced by iron/ascorba ... | 2003 | 12631441 |
| 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 |
| direct reduction of n-acetoxy-phip by tea polyphenols: a possible mechanism for chemoprevention against phip-dna adduct formation. | the chemopreventive effect of tea against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip)-dna adduct formation and its mechanism were studied. rats were exposed to freshly prepared aqueous extracts of green tea (3% (w/v)) as the sole source of drinking water for 10 days prior to administration with a single dose of phip (10 mg/kg body weight) by oral gavage. phip-dna adducts in the liver, colon, heart, and lung were measured using the 32p-postlabelling technique. rats pre-treated with tea ... | 2003 | 12628517 |
| 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 |
| effects of black tea theafulvins on aflatoxin b(1) mutagenesis in the ames test. | black tea theafulvins, a fraction of thearubigins isolated from black tea aqueous infusions, potentiated the mutagenic activity of the mycotoxin aflatoxin b(1) in the ames test, in the presence of a hepatic s9 activation system derived from aroclor 1254-treated rats. in contrast, when the s9 activation system was replaced with isolated microsomes, theafulvins suppressed the mutagenicity of the mycotoxin. when microsomal metabolism was terminated after metabolic activation of the mycotoxin, incor ... | 2003 | 12621070 |
| antigenotoxic potential of certain dietary constituents. | the human diet contains a variety of compounds that exhibit chemopreventive effects towards an array of xenobiotics. in the present study, the antigenotoxic potential of selected dietary constituents including diallyl sulfide (das), indole-3-carbinol (i3c), curcumin (cur), and black tea polyphenols (btp) has been evaluated in the salmonella typhimurium reverse mutation and mammalian in vivo cytogenetic assays. in addition, the anticlastogenic effect of the above dietary constituents was identifi ... | 2003 | 12616623 |
| regulation of hazardous exposure by protective exposure: modulation of phase ii detoxification and lipid peroxidation by camellia sinensis and swertia chirata. | many natural compounds are now known to have a modulatory role on physiological functions and biotransformation reactions involved in the detoxification process, thereby affording protection from cytotoxic, genotoxic, and metabolic actions of environmental toxicants. as part of a programme on evaluation of food, beverage, and traditional medicinal plants for their anticarcinogenic activity, their effects on detoxification enzymes were also studied. the present report deals with camellia sinensis ... | 2003 | 12616622 |
| indonesian medicinal plants. xxv. cancer cell invasion inhibitory effects of chemical constituents in the parasitic plant scurrula atropurpurea (loranthaceae). | six fatty acids (1-6), two xanthines (7, 8), two flavonol glycosides (9, 10), one monoterpene glucoside (11), one lignan glycoside (12), and four flavanes (13-16) were clarified by a bioassay-guided separation as chemical constituents of scurrula atropurpurea (loranthaceae), a parasitic plant of the tea plant thea sinensis (theaceae). among these constituents, it was found that the alkynic fatty acid octadeca-8,10,12-triynoic acid (6) exhibits a more potent inhibitory effect on cancer cell invas ... | 2003 | 12612428 |
| 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 |
| buckwheat honey increases serum antioxidant capacity in humans. | honey has been known to exert significant in vitro antioxidant activity, in part due to its phenolic content. however, conclusions that the antioxidants in honey are or are not efficacious in the human body cannot be reached if its antioxidant action is not assessed as part of a human study. in the present study, the acute effect of consumption of 500 ml of water, water with buckwheat honey, black tea, black tea with sugar, or black tea with buckwheat honey on serum oxidative reactions was exami ... | 2003 | 12590505 |
| 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 |
| [experimental studies on antioxidation of extracts from several plants used as both medicines and foods in vitro]. | the scavenging effects of 8 extracts from several plants used as both medicines and foods on oxygen free radicals were studied in vitro. | 2000 | 12575260 |
| ntp toxicology and carcinogenesis studies of theophylline (cas no. 58-55-9) in f344/n rats and b6c3f1 mice (feed and gavage studies). | theophylline is an alkaloid found in tea (thea sinensis) and chocolate and is structurally related to caffeine and theobromine. theophylline is used as a pharmaceutical agent. it stimulates the heart and central nervous system, relaxes the smooth muscles of the bronchi and blood vessels, and causes diuresis. the drug is used mainly as a bronchodilator in obstructive airway diseases, such as bronchial asthma, and for myocardial stimulation. theophylline was nominated for toxicologic and carcinoge ... | 1998 | 12571677 |
| inhibitory effects of tea and caffeine on uv-induced carcinogenesis: relationship to enhanced apoptosis and decreased tissue fat. | oral administration of green tea or caffeine to hairless skh-1 mice for 2 weeks stimulated uv-induced increases in apoptotic sunburn cells in the epidermis, and a similar effect was observed when caffeine was applied topically immediately after uv. in mice pretreated with uv for 22 weeks (high-risk mice without tumors), topical applications of caffeine 5 days a week for 18 weeks with no further uv treatment inhibited carcinogenesis and stimulated apoptosis in the tumors. oral administration of g ... | 2002 | 12570332 |
| 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 |
| soy phytochemicals and tea bioactive components synergistically inhibit androgen-sensitive human prostate tumors in mice. | although high doses of single bioactive agents may have potent anticancer effects, the chemopreventive properties of the asian diet may result from interactions among several components that potentiate the activities of any single constituent. in asia, where intake of soy products and tea consumption are very high, aggressive prostate cancer is significantly less prevalent in asian men. the objective of the present study was to identify possible synergistic effects between soy and tea components ... | 2003 | 12566493 |
| 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 |
| apoptogenic effects of black tea on ehrlich's ascites carcinoma cell. | next to water, tea is the most ancient and widely consumed beverage in the world. epidemiological studies have suggested a cancer protective effect, but the results obtained so far are not conclusive. in the current study, mechanisms of the apoptogenic effect of black tea extract were delineated. black tea administration to ehrlich's ascites carcinoma (eac)-bearing swiss albino mice caused a significant decrease in the tumor cell count in a dose-dependent manner. flowcytometric analysis showed a ... | 2003 | 12538351 |
| a mechanism of the thearubigin fraction of black tea (camellia sinensis) extract protecting against the effect of tetanus toxin. | the aim of the present study was to elucidate the mechanism of the protective effect of black tea extract's thearubigin fraction against the action of tetanus toxin. the effects of thearubigin fraction extracted from a black tea infusion were examined for neuromuscular blocking action on tetanus toxin in mouse phrenic nerve-diaphragm preparations and on the binding of this toxin to the synaptosomal membrane preparations of rat cerebral cortices. the interaction between tetanus toxin and thearubi ... | 2002 | 12533914 |
| efficacy and safety of herbal stimulants and sedatives in sleep disorders. | world-wide use of herbal medicines is increasing, following regulatory and manufacturing developments. herbs are attractive alternative medications to many patients with sleep disorders, who may be averse to using conventional drugs. we review here the most common herbal stimulants and sedatives. caffeine, in herbal teas, black tea, coffee, soft drinks and pharmaceuticals, is used widely to control sleepiness, but more research is needed on its use in sleep disorders. ephedra, and its constituen ... | 2000 | 12531167 |
| 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 |
| epigallocatechin-3-gallate selectively inhibits interleukin-1beta-induced activation of mitogen activated protein kinase subgroup c-jun n-terminal kinase in human osteoarthritis chondrocytes. | activation of mitogen activated protein kinases (mapk) is a critical event in pro-inflammatory cytokine-induced signaling cascade in synoviocytes and chondrocytes that lead to the production of several mediators of cartilage damage in an arthritic joint. green tea (camellia sinensis) is a widely consumed beverage and we earlier showed that polyphenols present in green tea (gtp) inhibit the development of inflammation and cartilage damage in an animal model of arthritis. in this study we evaluate ... | 2003 | 12507586 |
| heterologous nuclear and chloroplast microsatellite amplification and variation in tea, camellia sinensis. | the advantage of the cross transferability of heterologous chloroplast and nuclear microsatellite primers was taken to detect polymorphism among 24 tea (camellia sinensis (l.) o. kuntze) genotypes, including both the assamica and the sinensis varieties. primer information was obtained from the closely related camellia japonica species for four nuclear microsatellites, and from nicotiana tabaccum for seven universal chloroplast microsatellites. all of the nuclear microsatellite loci tested genera ... | 2002 | 12502248 |
| 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 |
| [isolation and determination of an antidote for botulinum neurotoxin from black tea extract]. | the botulinum neurotoxin produced by clostridium botulinum exhibits the strongest neurotoxicity, and causes botulism in mammals. we have found an inactivator for clostridial neurotoxins in black tea extract (thearubigin fraction) as a natural foodstuff. in this study, we have isolated and identified the inactivators. the activity against the neuromuscular blocking action of botulinus neurotoxin type a was examined in mouse phrenic nerve diaphram preparation. the purification procedure of the ina ... | 2002 | 12491801 |
| cloning of beta-primeverosidase from tea leaves, a key enzyme in tea aroma formation. | a beta-primeverosidase from tea (camellia sinensis) plants is a unique disaccharide-specific glycosidase, which hydrolyzes aroma precursors of beta-primeverosides (6-o-beta-d-xylopyranosyl-beta-d-glucopyranosides) to liberate various aroma compounds, and the enzyme is deeply concerned with the floral aroma formation in oolong tea and black tea during the manufacturing process. the beta-primeverosidase was purified from fresh leaves of a cultivar for green tea (c. sinensis var sinensis cv yabukit ... | 2002 | 12481100 |
| 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 |
| accumulation of epigallocatechin quinone dimers during tea fermentation and formation of theasinensins. | production and accumulation of catechin dimer quinones during tea fermentation were chemically confirmed for the first time by trapping as phenazine derivatives. direct treatment of the fermented tea leaves with o-phenylenediamine yielded five phenazine derivatives (8-12) of o-quinones of an epigallocatechin dimer and its galloyl esters (13-16), in which two flavan units were linked at the b-rings through a c-c bond. atrop isomerism of the biphenyl bonds was shown to be the r configuration, sugg ... | 2002 | 12444680 |
| 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 |
| protection by beverages, fruits, vegetables, herbs, and flavonoids against genotoxicity of 2-acetylaminofluorene and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) in metabolically competent v79 cells. | chinese hamster lung fibroblasts, genetically engineered for the expression of rat cytochrome p450 dependent monooxygenase 1a2 and rat sulfotransferase 1c1 (v79-rcyp1a2-rsult1c1 cells), were utilized to check for possible protective effects of beverages of plant origin, fruits, vegetables, and spices against genotoxicity induced by 2-acetylaminofluorene (aaf) or 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip). antigenotoxic activities of juices from spinach and red beets against aaf could ... | 2002 | 12438004 |
| tea enhances insulin activity. | the most widely known health benefits of tea relate to the polyphenols as the principal active ingredients in protection against oxidative damage and in antibacterial, antiviral, anticarcinogenic, and antimutagenic activities, but polyphenols in tea may also increase insulin activity. the objective of this study was to determine the insulin-enhancing properties of tea and its components. tea, as normally consumed, was shown to increase insulin activity >15-fold in vitro in an epididymal fat cell ... | 2002 | 12428980 |
| inhibition of 12-o-tetradecanoylphorbol-13-acetate-induced inflammatory skin edema and ornithine decarboxylase activity by theaflavin-3,3'-digallate in mouse. | among black tea polyphenols, theaflavins were generally considered to be the most effective in cancer chemoprevention. in this study, we examined the inhibitory effects of black tea polyphenols, including theaflavin (tf-1), a mixture (tf-2) of theaflavin-3-gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate (tf-3), and the green tea polyphenol (-)-epigallocatechin-3-gallate (egcg) on 12-o-tetradecanoylphorbol-13-acetate (tpa)-induced edema and ornithine decarboxylase (odc) activity. top ... | 2002 | 12416263 |
| anti-oxidative, anti-inflammatory and hepato-protective effects of ligustrum robustum. | aqueous extract of processed leaves of ligustrum robustum could dose-dependently scavenge superoxide radicals, inhibit lipid peroxidation, and prevent aaph-induced hemolysis of red blood cells. in comparison with green tea, oolong tea and black tea, processed leaves of l. robustum exhibited comparable antioxidant potency in scavenging superoxide radicals and in preventing red blood cell hemolysis. by activity-guided fractionation, a glycoside-rich fraction named fraction b2 was separated and dem ... | 2002 | 12413708 |
| antimutagenic effects of black tea (world blend) and its two active polyphenols theaflavins and thearubigins in salmonella assays. | almost two thirds of the world population consume tea everyday. tea is processed differently in different parts of the world to give green (20%), black (78%) or oolong tea (2%). the antimutagenic and anticarcinogenic activities of green tea were extensively investigated compared with those of black tea. considering the potent antimutagenic effects of green tea we recognized the need to evaluate the antimutagenic effects of black tea (world blend tea, southern tea co., marietta, ga) in salmonella ... | 2002 | 12410547 |
| 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 |
| green tea (camellia sinensis) protects against selenite-induced oxidative stress in experimental cataractogenesis. | cataract is the leading cause of blindness worldwide. it is a multifactorial disease primarily associated with oxidative stress produced by free radicals. the protection offered by various antioxidants in cataract development is well established. polyphenolic compounds present in green tea (camellia sinensis) are reported to possess antioxidant property in various pathological conditions. the present study was undertaken to evaluate the anticataract potential of green tea leaf (gtl) extract in t ... | 2002 | 12297700 |
| sharing a bowl of tea. | soshitsu sen's keynote speech before a symposium on population and the environment is summarized unofficially by the editorial staff. the instability of human thinking is given as the cause for the present destruction of the environment. in a visit to the his majesty king of sweden, sen remarked that stabilizing human minds can be achieved within the tea ceremony through "serving tea heartily, receiving it with gratitude, and offering it to another." in this way, the spirit of concern for oth ... | 1993 | 12286476 |
| comparative antimutagenic and anticlastogenic effects of green tea and black tea: a review. | tea is the most popular beverage next to water, consumed by over two-thirds of the world's population. it is processed in different ways in different parts of the world to give green, black or oolong tea. experimental studies have demonstrated the significant antimutagenic and anticlastogenic effects of both green and black tea and its polyphenols in multiple mutational assays. in the present review, we have attempted to evaluate and update the comparative antimutagenic and anticlastogenic effec ... | 2002 | 12220589 |
| epigallocatechin-3-gallate inhibits interleukin-1beta-induced expression of nitric oxide synthase and production of nitric oxide in human chondrocytes: suppression of nuclear factor kappab activation by degradation of the inhibitor of nuclear factor kappab. | the proinflammatory cytokine interleukin-1beta (il-1beta) induces the production of high levels of nitric oxide (no) in human chondrocytes. green tea (camellia sinensis) polyphenols are potent antiinflammatory agents and have been shown to inhibit no production in tumor cell lines. in the present study, we examined the effect of epigallocatechin-3-gallate (egcg), a green tea polyphenol, on il-1beta-induced production of no in primary human osteoarthritis (oa) chondrocytes. | 2002 | 12209512 |
| 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 |
| effect of black tea on (iso-)prostaglandins and platelet aggregation in healthy volunteers. | flavonoids among others are found in tea. many of them were shown to exhibit antioxidative action in vitro. we examined the effect of a 1-month consumption of 500 ml black tea containing 2.0 mg quercetin. while single tea consumption 2 h after finishing the intake did not affect any of the parameters (8-epi-pgf(2 alpha) in plasma and serum, 11-dh-txb(2) and adp-induced platelet aggregation) examined at all, 1-week consumption and even more than 1 month regular tea intake significantly decreased ... | 2013 | 12144875 |
| the effects of catechin on superoxide dismutase activity and its gene expression in pheochromocytoma cells. | overexpression of manganese superoxide dismutase (mnsod) cdna via plasmid transfection leads to growth inhibition in vitro and in vivo in various human cancers. polyphenolic compounds such as catechin isolated from tea bush camellia sinensis has been shown to have anticancer effect in vitro. this study evaluated the effect of catechin on the mnsod activity and mrna level of pheochromocytoma cells (pc-12). | 2002 | 12135191 |
| effects of tea components on the response of gaba(a) receptors expressed in xenopus oocytes. | to study the effects of tea components on ionotropic gamma-aminobutyric acid (gaba) receptor response, ionotropic gaba receptors (gaba(a) receptors) were expressed in xenopus oocytes by injecting crnas synthesized from cloned cdnas of the alpha(1) and beta(1) subunits of the bovine receptors, and their electrical responses were measured by a voltage clamping method. extracts of green tea, black tea, and oolong tea in an aqueous solution induced the gaba-elicited response, which showed that these ... | 2002 | 12083865 |
| protective effect of boldo and tea infusions on the visible light-mediated pro-oxidant effects of vitamin b2, riboflavin. | the effect of boldo and black tea infusions on the pro-oxidant effects of vitamin b2, riboflavin (rf), when exposed to the action of visible light was studied. the amounts of antioxidants present in boldo and tea infusions were evaluated by a procedure based on the bleaching of preformed 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cations and were expressed as 6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic acid equivalent concentrations. the quenching rate constants of sing ... | 2002 | 12081319 |
| the mechanism underlying the protective effect of the thearubigin fraction of black tea (camellia sinensis) extract against the neuromuscular blocking action of botulinum neurotoxins. | the aim of the present study was to elucidate the mechanism of the protective effect of black tea extract, the thearubigin fraction, against the neuromuscular blocking action of botulinum neurotoxin types a, b, and e. the effects of thearubigin fraction extracted from a black tea infusion were examined on the neuromuscular blocking action of botulinum neurotoxin types a, b, and e in mouse phrenic nerve-diaphragm preparations and on the binding of these toxins to rat cerebrocortical synaptosomes. ... | 2002 | 12076314 |
| mechanisms of chronic disease causation by nutritional factors and tobacco products and their prevention by tea polyphenols. | the beverage tea, from the top leaves of the plant camellia sinensis is one of the most widely used beverages in the world, second only to water. black and green tea have mostly similar actions. the active components are polyphenols, mainly epigallocatechin gallate in green tea, and the tea leaf polyphenol oxidase mediated oxidation to oolong and black tea, yielding other polyphenols, theaflavin and thearubigins. there is 40-50 mg caffeine in a 160-ml cup of tea. the chemopreventive effects of t ... | 2002 | 12067577 |
| red wine and black tea polyphenols modulate the expression of cycloxygenase-2, inducible nitric oxide synthase and glutathione-related enzymes in azoxymethane-induced f344 rat colon tumors. | polyphenolic compounds extracted from red wine (we) and black tea (bt), 50 mg/(kg. d), inhibit the promotion phase of the colon carcinogenesis process induced by azoxymethane (aom) in rodents. to investigate possible mechanisms of this protective activity, we evaluated by rt-pcr the gene expression of cycloxygenase-2 (cox-2), inducible no synthase (inos), gamma-glutamylcysteine synthetase (gamma-gcs) and two isoforms of glutathione s-transferase (gst), gst-p and gst-m2, in 30 aom-induced tumors ... | 2002 | 12042461 |