Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| tea pigments inhibit the production of type 1 (t(h1)) and type 2 (t(h2)) helper t cell cytokines in cd4(+) t cells. | tea pigments are oxidized products of polyphenols derived from tea leaves (camellia sinensis). theaflavins are constituents of tea pigments with antioxidant, antineoplastic and antiinflammatory properties similar to their parent compounds. the biological properties of polyphenols and theaflavins have been linked to their capacity to inhibit the activation of nuclear factor-kappab (nf-kappab), a transcription factor, which is critically involved in the molecular regulation of a number of proinfla ... | 2002 | 11807963 |
| tea flavonoids: bioavailability in vivo and effects on cell signaling pathways in vitro. | the elucidation of the potential health benefits of tea beverage continues to be a focus of research in many laboratories. beneficial effects of tea have been particularly evident in animal tumorigenesis models, with green and black tea frequently demonstrating similar effectivity. human data are now emerging to support a beneficial role for tea in cardiovascular disease, but the data with respect to cancer risk at various sites remain inconclusive. the constituent flavonoids of green and black ... | 2001 | 11813977 |
| substrate specificity of beta-primeverosidase, a key enzyme in aroma formation during oolong tea and black tea manufacturing. | we synthesized nine kinds of diglycosides and a monoglycoside of 2-phenylethanol to investigate the substrate specificity of the purified beta-primeverosidase from fresh leaves of a tea cultivar (camellia sinensis var. sinensis cv. yabukita) in comparison with the apparent substrate specificity of the crude enzyme extract from tea leaves. the crude enzyme extract mainly showed beta-primeverosidase activity, although monoglycosidases activity was present to some extent. the purified beta-primever ... | 2001 | 11826969 |
| regular ingestion of black tea improves brachial artery vasodilator function. | a higher intake of black tea has been associated with lower cardiovascular disease risk. the antioxidant effects of tea polyphenols may enhance endothelial function and thereby reduce the risk of coronary events. the objective of the present study was to determine whether regular ingestion of black tea can improve brachial artery vasodilator function. the effects of regular ingestion of 5 cups per day of black tea for 4 weeks were compared with control conditions (hot water ingestion) in 21 subj ... | 2002 | 11834139 |
| nanoparticles in plant extracts: influence of drugs on the formation of nanoparticles and precipitates in black tea infusions. | the influence of the neuroleptics fluphenazine and promethazine on the formation of nanoparticles in aqueous tea infusions was investigated using photon correlation spectroscopy. formation of nanoparticles and of precipitates was observed in decaffeinated tea and caffeine-containing tea. the amount of drug in the nanoparticle fraction was determined at different starting concentrations using high-performance liquid chromatography. in the case of fluphenazine, between 8 and 30% are assigned to th ... | 2002 | 11849911 |
| interactions between flavonoids and proteins: effect on the total antioxidant capacity. | flavonoids are potent antioxidants. it is also known that flavonoids bind to proteins. the effect of the interaction between tea flavonoids and proteins on the antioxidant capacity was examined. their separate and combined antioxidant capacities were measured with the trolox equivalent antioxidant capacity (teac) assay. it was observed that the antioxidant capacity of several components of green and black tea with alpha-, beta-, and kappa-casein or albumin is not additive; that is, a part of the ... | 2002 | 11853501 |
| congou tea drinking and oesophageal cancer in south china. | the study from a large hospital-based case-control for 1248 cases with oesophageal cancer and the same number of controls in south china showed that congou, a grade of chinese black tea, may protect against cancers of the oesophagus and reduce the risk of a combination of alcohol drinking and smoking (especially smoking), regardless of temperature when drinking. | 2002 | 11875696 |
| catechins from green tea (camellia sinensis) inhibit bovine and human cartilage proteoglycan and type ii collagen degradation in vitro. | polyphenolic compounds from green tea have been shown to reduce inflammation in a murine model of inflammatory arthritis, but no studies have been undertaken to investigate whether these compounds are protective to joint tissues. we therefore investigated the effects of catechins found in green tea on cartilage extracellular matrix components using in vitro model systems. bovine nasal and metacarpophalangeal cartilage as well as human nondiseased, osteoarthritic and rheumatoid cartilage were cul ... | 2002 | 11880552 |
| antibacterial activity of black tea (camelia sinensis) extract against salmonella serotypes causing enteric fever. | alcoholic extract of black tea (camelia sinensis) was assayed for its antibacterial activity against salmonella serotypes causing enteric fever viz., salmonella typhi and salmonella paratyphi a. while all strains of s. paratyphi a tested were found sensitive, only 42.19% of s. typhi strains were inhibited by this extract. further minimum inhibitory concentration (mic) and minimum bactericidal concentration (mbc) of black tea extract against s. paratyphi a was less compared with that against s. t ... | 2001 | 11883337 |
| acute effects of ingestion of black tea on postprandial platelet aggregation in human subjects. | results of population studies suggest that black tea can reduce cardiovascular risk. effects of black-tea polyphenols to reduce platelet aggregability may help to explain any benefits. given that black tea is often consumed with and after meals, and man spends much of his life in the postprandial state, the objective of the present study was to investigate the acute effects of ingestion of black tea on postprandial platelet aggregation ex vivo. twenty healthy participants had platelet aggregatio ... | 2002 | 11895166 |
| synthesis of theaflavin from epicatechin and epigallocatechin by plant homogenates and role of epicatechin quinone in the synthesis and degradation of theaflavin. | oxidation products of (-)-epicatechin and (-)-epigallocatechin by treatment with homogenates of 62 plants belonging to 49 families were compared. forty-six plants were capable of synthesizing theaflavin, a black tea pigment, regardless of whether they contained catechins. loquat, japanese pear, and blueberry had activities higher than that of fresh tea leaves after 5 h of treatment; furthermore, these plants oxidized theaflavin to theanaphthoquinone. an additional new metabolite, dehydrotheasine ... | 2002 | 11902970 |
| signal transduction pathways: targets for chemoprevention of skin cancer. | chemoprevention can be defined as the use of substances to interfere with the process of cancer development. although substantial progress has been made in elucidating the basis of carcinogenesis, further advances are needed to identify molecular and cellular targets for effective use of chemopreventive agents. hundreds of compounds have been identified as potential chemopreventive agents. however, the safety and efficacy of each substance must be thoroughly investigated. carcinogenesis is a mul ... | 2000 | 11905657 |
| evaluation of the antigenotoxic potential of monomeric and dimeric flavanols, and black tea polyphenols against heterocyclic amine-induced dna damage in human lymphocytes using the comet assay. | the polyphenolic dimers, epicatechin-4beta-8-catechin (b1), epicatechin-4beta-8-epicatechin (b2), catechin-4beta-8-catechin (b3), catechin-4beta-8-epicatechin (b4), and the gallate ester epicatechin-4beta-8-epicatechin gallate (b'2g) were isolated from grape seeds, and theaflavins and theafulvins from black tea brews. the ability of these naturally-occurring polyphenols to afford protection against the genotoxicity of the heterocyclic amine 3-amino-1-methyl-5h-pyrido[4,3-b]indole (trp-p-2) was c ... | 2002 | 11909753 |
| antioxidant activity of black tea vs. green tea. | 2002 | 11925478 | |
| anti-invasive effects of green tea polyphenol epigallocatechin-3-gallate (egcg), a natural inhibitor of metallo and serine proteases. | several reports have attributed to green tea chemopreventive and therapeutic properties. epidemiological studies have linked the regular use of green tea to a reduced incidence of breast and colon carcinomas. tea contains several antioxidants, including polyphenols of the catechin (green tea) and theaflavin (black tea) groups. green tea derivatives have been shown to act in vitro and in vivo as anti-inflammatory, anti-viral and anti-tumor drugs. despite the extensive body of data only few studie ... | 2002 | 11928805 |
| effects of black tea extract on carbon tetrachloride-induced lipid peroxidation in liver, kidneys, and testes of rats. | previous studies have shown that green tea and black tea have antioxidant effects and chemopreventive activity against chronic disease including some forms of cancer. we have, therefore, examined the effects of an aqueous extract of black tea against carbon tetrachloride-induced lipid peroxidation as determined by the formation of thiobarbituric acid reactive substances in liver, kidneys and testes of rats. a 0.7% black tea extract was used which contained 2 mg of black tea extract solids per ml ... | 2002 | 11933136 |
| tea polyphenols inhibit the formation of mutagens during the cooking of meat. | powerful mutagens are formed during the broiling or frying of meat. these mutagens cause specific cancers in animal models, and epidemiological studies suggest that they increase the risk of breast and colon cancer. it is important, therefore, to inhibit the formation of these mutagens. application of tea polyphenols, polyphenon 60 from green tea, and polyphenon b from black tea, to both surfaces of ground beef before cooking inhibits the formation of the mutagens in a dose-related fashion. this ... | 2002 | 11943606 |
| multielement determination and speciation of major-to-trace elements in black tea leaves by icp-aes and icp-ms with the aid of size exclusion chromatography. | a multielement determination of major-to-trace elements in black tea leaves and their tea infusions was carried out by icp-aes (inductively coupled plasma atomic emission spectrometry) and icp-ms (inductively coupled plasma mass spectrometry). tea infusions were prepared as usual tea beverage by brewing black tea leaves in boiling water for 5 min. about 40 elements in tea leaves and tea infusions could be determined over the wide concentration range in 8 orders of magnitude. the extraction effic ... | 2001 | 11990615 |
| novel epr characterization of the antioxidant activity of tea leaves. | electron paramagnetic resonance (epr) spectroscopy is utilized to investigate several categories of green and black tea: twining green tea (tgt), chinese green tea (cgt), red-labels black tea (rbt). basically, two epr signals from all the studied samples are observed: one of them is a very weak sharp epr signal with deltahpp approximately 10 g and g-factor = 2.00023 superimposed on the other broad signal with deltahpp approximately 550 g and g-factor = 2.02489. the broad signal is a characterist ... | 2002 | 11993474 |
| [cancer prevention with green tea: reality and wishful thinking]. | different processing of the leaves of the tea plant camellia sinensis yields green or black tea, the subject of numerous investigations on the preventive effects on chronic degenerative diseases. the tea polyphenols, in particular (-)-epigallocatechin gallate (egcg) were found to account for most of the protective effects. since the concentration of egcg is 5 times higher in green than in black tea, it is assumed that green tea possesses a greater preventive potential. protection against cancer ... | 2002 | 11998565 |
| aflatoxin in detannin coffee and tea and its destruction. | the aflatoxins produced byaspergillus parasiticus var. globosus imi 12090 in detannin-caffeinated coffee and black tea were five times more concentrated than in regular coffee and tea. the activity of caffeine and tannin on the fungus growth and aflatoxin production in liquid broth was tested at three levels: viz. 0.1, 0.3, and 0.6%. tannin and caffeine induced 95% inhibition in aflatoxins at 0.3% and 0.6%, respectively. the antiaflatoxigenic properties of regular coffee and tea appear to be due ... | 2002 | 12009113 |
| theacrine (1,3,7,9-tetramethyluric acid) synthesis in leaves of a chinese tea, kucha (camellia assamica var. kucha). | theacrine (1,3,7,9-tetramethyluric acid) and caffeine were the major purine alkaloids in the leaves of an unusual chinese tea known as kucha (camellia assamica var. kucha). endogenous levels of theacrine and caffeine in expanding buds and young leaves were ca. 2.8 and 0.6-2.7% of the dry wt, respectively, but the concentrations were lower in the mature leaves. radioactivity from s-adenosyl-l-[methyl-14c]methionine was incorporated into theacrine as well as theobromine and caffeine by leaf disks ... | 2002 | 12009315 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |