Publications

selection of column and gradient elution system for the separation of catechins in green tea using high-performance liquid chromatography.	a study of a variety of stationary phases and elution conditions for the liquid chromatographic (lc) determination of six biologically active green tea catechins has resulted in the development of two well-defined, reproducible systems for such analyses which overcome limitations of previously described methods. comparison of six reversed-phase columns indicates that deactivated stationary phases, which utilize ultrapure silica and maximize coverage of the silica support, provide significantly i ...	1998	9474785
identification of endogenous gibberellins in the leaves and xylem sap of tea plants.	endogenous gibberellins (gas) in the young leaves and xylem sap of tea plants (camellia sinensis l.) were analyzed by gc-ms. the following gas were identified by comparing their mass spectra and kris with those of authentic specimens: ga9 and ga20 in the leaves; ga9, ga12, ga15, ga20, ga44, ga51 and ga53 in the xylem sap.	1999	27392877
biosynthesis and catabolism of caffeine in low-caffeine-containing species of coffea.	leaves of coffea salvatrix, coffea eugenioides, and c. bengalensis contain approximately 3-7-fold lower levels of caffeine than those of coffea arabica. there was more extensive biosynthesis of caffeine from [8-(14)c]adenine in young leaves of c. arabica than in c. salvatrix, c. eugenioides, and c. bengalensis. degradation of [8-(14)c]caffeine, which is negligible in leaves of c. arabica, was also very slow in c.salvatrix and c. bengalensis. in contrast, [8-(14)c]caffeine was catabolized rapidly ...	1999	10552667
statistical analysis of salivary ph changes after the intake of black tea and yerba maté supplemented with sweeteners.	many studies have demonstrated the effect of various beverages on hard tissues of the mouth. sugar consumption has also been avoided because it is associated with caries activity, and artificial sweetener research has been promoted. in this paper, data about the buffer capacity of black tea and yerba mate supplemented with sugar or one of two artificial sweeteners (barny diet and nutrasweet) were examined. salivary ph variations after the ingestion of both infusions were statistically analysed. ...	1999	10453132
proconvulsive effect of tea (camellia sinensis) in mice.	investigations were carried out to evaluate the effect of acute and chronic administration of both black and green tea on three models of experimentally induced convulsions in mice. tea extract (both black and green) significantly accelerated the onset of convulsion, increased the duration of convulsion and mortality in mice. since both the extracts failed to alter the gaba level in brain, based on the earlier report that both black and green tea might act on ca(2+) channels, it can be suggested ...	1999	10441775
effects on blood pressure of drinking green and black tea.	the flavonoid components of tea have been associated in epidemiological studies with a decreased risk of cardiovascular disease. flavonoids have been shown to have antioxidant and vasodilator effects in vitro; we therefore postulated that drinking green or black tea attenuates the well-characterized acute pressor response to caffeine and lowers blood pressure during regular consumption.	1999	10404946
scavenging of hydrogen peroxide and inhibition of ultraviolet light-induced oxidative dna damage by aqueous extracts from green and black teas.	aqueous extracts of green and black teas have been shown to inhibit a variety of experimentally induced animal tumors, particularly ultraviolet (uv) b light-induced skin carcinogenesis. in the present study, we compared the effects of different extractable fractions of green and black teas on scavenging hydrogen peroxide (h2o2), and uv irradiation-induced formation of 8-hydroxy 2'-deoxyguanosine (8-ohdg) in vitro. green and black teas have been extracted by serial chloroform, ethyl acetate and n ...	1999	10401606
effects of oral administration of tea, decaffeinated tea, and caffeine on the formation and growth of tumors in high-risk skh-1 mice previously treated with ultraviolet b light.	treatment of skh-1 mice with ultraviolet b light (uv-b, 30 mj/cm2) twice a week for 22-23 weeks resulted in tumor-free animals with a high risk of developing malignant and nonmalignant tumors during the next several months in the absence of further uv-b treatment (high-risk mice). in three separate experiments, oral administration of green tea or black tea (4-6 mg tea solids/ml) as the sole source of drinking fluid for 18-23 weeks to these high-risk mice inhibited the formation and decreased the ...	1999	10368809
purification and characterization of caffeine synthase from tea leaves.	caffeine synthase (cs), the s-adenosylmethionine-dependent n-methyltransferase involved in the last two steps of caffeine biosynthesis, was extracted from young tea (camellia sinensis) leaves; the cs was purified 520-fold to apparent homogeneity and a final specific activity of 5.7 nkat mg-1 protein by ammonium sulfate fractionation and hydroxyapatite, anion-exchange, adenosine-agarose, and gel-filtration chromatography. the native enzyme was monomeric with an apparent molecular mass of 61 kd as ...	1999	10364410
tea and health: the underlying mechanisms.	detailed multidisciplinary research on the effect of tea and the associated tea polyphenols has led to major advances on the underlying mechanisms. in most studies, green and black tea have similar effects, four of which are reviewed in this paper. 1) tea polyphenols are powerful antioxidants that may play a role in lowering the oxidation of ldl-cholesterol, with a consequent decreased risk of heart disease, and also diminish the formation of oxidized metabolites of dna, with an associated lower ...	1999	10202402
inhibitory effect of green and black tea on tumor growth.	the administration of green tea, black tea, or (-)-epigallocatechin gallate inhibited the growth of established nonmalignant and malignant tumors in tumor-bearing mice. in experiments with black tea, we found that its oral administration inhibited dna synthesis and enhanced apoptosis in both nonmalignant and malignant tumors in tumor-bearing mice.	1999	10202394
preclinical efficacy studies of green and black tea extracts.		1999	10202390
plasma and lipoprotein levels of tea catechins following repeated tea consumption.	epidemiological studies suggest that antioxidant flavonoids in tea may reduce the risk of cardiovascular disease, possibly via protection of low-density lipoproteins (ldl) against oxidation. however, the extent of absorption of tea flavonoids and their accumulation in ldl during regular consumption of tea is not clear. therefore we investigated plasma and lipoprotein levels of catechins during tea consumption and the impact on ldl oxidizability ex vivo. eighteen healthy adults consumed, in an in ...	1999	10202389
theaflavin-3,3'-digallate from black tea blocks the nitric oxide synthase by down-regulating the activation of nf-kappab in macrophages.	nitric oxide (no) plays an important role in inflammation and also in multiple stages of carcinogenesis. we investigated the effects of various tea polyphenols, including theaflavin, a mixture of theaflavin-3-gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate, thearubigin, and (-)-epigallocatechin-3-gallate on the induction of no synthase in lipopolysaccharide-activated murine macrophages, raw 264.7 cells. theaflavin-3,3'-digallate was found to be stronger than (-)-epigallocatechin-3-g ...	1999	10079014
application of near-infrared reflectance spectroscopy to the simultaneous prediction of alkaloids and phenolic substances in green tea leaves.	a near-infrared reflectance spectroscopic (nirs) method for the prediction of polyphenol and alkaloid compounds in the leaves of green tea [camellia sinensis (l.) o. kuntze] was developed. reference measurements of the individual catechins, gallic acid, caffeine, and theobromine were performed by reversed-phase hplc. the total polyphenols were determined according to the colorimetric folin-ciocalteu assay. using the partial least-squares algorithm, very good calibration statistics were obtained ...	1999	10606573
inhibition of tpa-induced protein kinase c and transcription activator protein-1 binding activities by theaflavin-3,3'-digallate from black tea in nih3t3 cells.	tea is one of the most popular beverages in the world. several reports have shown that both green tea and black tea were able to inhibit tumor cell proliferation in animal models. in this study, we investigated the inhibitory effects of black tea polyphenols including theaflavin (tf-1), the mixture (tf-2) of theaflavin-3-gallate (tf-2a), and theaflavin-3'-gallate (tf-2b), theaflavin-3,3'-digallate (tf-3), thearubigin (tr), and a major green tea polyphenol (-)-epigallocatechin-3-gallate (egcg) on ...	1999	10563991
total antioxidant capacity of teas by the ferric reducing/antioxidant power assay.	this study aimed to compare in vitro antioxidant power of different types of tea (camellia sinensis). the ferric reducing/antioxidant power (frap) assay was used to measure the total antioxidant power of freshly prepared infusions of 25 types of teas. results showed that different teas had widely different in vitro antioxidant power and that the antioxidant capacity was strongly correlated (r = 0. 956) with the total phenolics content of the tea. expressed as micromol of antioxidant power/g of d ...	1999	10563944
green tea (camellia sinensis) extract and its possible role in the prevention of cancer.	the american cancer society estimates that in the 1980s more than 4. 5 million americans died of cancer. in addition, there were nearly nine million new cases and about 12 million people were under medical care for cancer. with cancer being the second most common cause of death in the united states population, the possibility that readily-available natural substances may be beneficial in the prevention of cancer warrants closer examination. a growing body of research has demonstrated green tea p ...	1999	10559550
novel antiallergic catechin derivatives isolated from oolong tea.	two catechin derivatives (c-1 and c-2) with potent antiallergic activity were isolated from taiwanese oolong tea by hplc techniques. from nmr and fab-ms analyses, the structures of c-1 and c-2 were elucidated as (-)-epigallocatechin 3-o-(3-o-methyl)gallate and (-)-epigallocatechin 3-o-(4-o-methyl)gallate, respectively. the oolong tea leaves contained 0.34% (dry weight) c-1 and 0.20% c-2. traces of c-2 were detected in only 1 of 15 varieties of green tea tested. c-1 was detected in 13 of 15 green ...	1999	10552469
(z)-3-hexenyl and trans-linalool 3,7-oxide beta-primeverosides isolated as aroma precursors from leaves of a green tea cultivar.	6-o-beta-d-xylopyranosyl-beta-d-glucopyranosides (beta-primeverosides) of (z)-3-hexenol and trans-linalool 3,7-oxide were newly isolated from fresh leaves of a tea cultivar (camellia sinensis var. sinensis cv. yabukita). in addition, the already identified beta-primeverosides of benzyl alcohol, methyl salicylate, and trans-linalool 3,6-oxide from an oolong tea cultivar were isolated from the yabukita cultivar. it was confirmed that all aglycones of the linalool oxide glycosides isolated here wer ...	1999	10540751
genetic and dietary predictors of cyp2e1 activity: a phenotyping study in hawaii japanese using chlorzoxazone.	cytochrome p4502e1 (cyp2e1) is considered to play an important role in the metabolic activation of procarcinogens such as n-nitrosoamines and low molecular weight organic compounds. an rsai polymorphism is present in the 5'-flanking region of the cyp2e1 gene, which could possibly affect its transcription. however, the relationship between genotype and the phenotypic catalytic activity of the enzyme has not been defined. also, the effects in humans of specific dietary factors, other than ethanol, ...	1999	10385138
a review of plants used in the treatment of liver disease: part two.	botanical medicines have been used traditionally by herbalists and indigenous healers worldwide for the prevention and treatment of liver disease. clinical research in this century has confirmed the efficacy of several plants in the treatment of liver disease, while basic scientific research has uncovered the mechanisms by which some plants provide their therapeutic effects. this article is part two in a review of botanicals used in the treatment of liver disease. curcuma longa (turmeric), camel ...	1999	10383482
antioxidant capacity and polyphenolic components of teas: implications for altering in vivo antioxidant status.	the oxygen radical absorbance capacity (orac) assay was used to determine the total antioxidant capacity of tea. green and black teas (n = 18) had a mean antioxidant capacity of 761.1 +/- 85.3 micromol trolox equivalents (te) per g dry matter. however, their antioxidant capacity varied from 235 micromol to over 1526 micromol trolox equivalents (te)/g dry matter, and total phenolics ranged from 32 to 147 mg/g in different commercial teas. one tea phenolics extract had an antioxidant capacity of 4 ...	1999	10202399
growth-inhibiting effects of coptis japonica root-derived isoquinoline alkaloids on human intestinal bacteria.	the growth-inhibiting activity of coptis japonica (makino) root-derived materials toward eight human intestinal bacteria was examined using an impregnated paper disk method and compared to that of four commercially available isoquinoline alkaloids [berberine sulfate (bs), berberine iodide (bi), palmatine chloride (pc), and palmatine sulfate(ps)], as well as that of thea sinensis leaf-derived epigallocatechin gallate (egcg). the biologically active constituents of the coptis extract were characte ...	1999	10552394
photoprotective effect of black tea extracts against uvb-induced phototoxicity in skin.	in previous studies, we showed that green tea and black tea extracts and their major polyphenolic constituents protect against uvb light-induced carcinogenesis in murine skin. all of these studies required chronic administration of tea extracts or specific constituents either topically or orally. however, it is not known whether acute or subchronic administration of black tea extracts or constituents can ameliorate uvb-induced early effects in skin. in the present study, cultured keratinocytes a ...	1999	10546558
metabolism of theanine, gamma-glutamylethylamide, in rats.	the metabolism of theanine, one of the major amino acid components in tea (camellia sinensis), was studied in rats. high-performance liquid chromatography (hplc) with fluorometric detection was used to evaluate the nature of theanine's metabolites in plasma, urine, and tissues. in the urine samples collected after administration of 100, 200, and 400 mg each of theanine, intact theanine, l-glutamic acid, and ethylamine, these compounds were detected in a dose-dependent manner. when 200 mg of thea ...	1999	10564022
fungi associated with black tea and tea quality in the sultanate of oman.	forty-eight samples of four popular commercial brands of black tea (camellia sinensis l.) were purchased from the local markets in muscat area, sultanate of oman. tea leaves were surveyed for mycoflora. five fungal species were isolated with a. niger as the most dominant in all the brands having percentage contamination ranging between 0.66% and 30.34%. other fungi isolated were aspergillusflavus, penicillium spp. and pacelomyces spp. but having average percentages of 0.6%, 0.84% and 0.21% respe ...	1999	10598069
comparison of digestion methods for determination of trace and minor metals in plant samples.	in this paper, three dissolution methods using pressure digestion vessels (low-, medium-, and high-pressure vessels) for the determination of metals in plant samples are described. the plackett-burman saturated factorial design was used to identify the significant factors influencing wet ashing and to select optimized dissolution conditions. the three methods were statistically compared (on-way anova) on the same sample; no significant differences were obtained. in all cases the relative standar ...	1999	10606575
antimicrobial activity of tea as affected by the degree of fermentation and manufacturing season.	bacillus subtilis, escherichia coli, proteus vulgaris, pseudomonas fluorescens, salmonella sp. and staphylococcus aureus were used to test the antimicrobial activity of tea flush extract and extracts of various tea products. among the six test organisms, p. fluorescens was the most sensitive to the extracts, while b. subtilis was the least sensitive. in general, antimicrobial activity decreased when the extents of tea fermentation increased. the antimicrobial activities of tea flush extract and ...	1999	10426448
disorganization of cell division of methicillin-resistant staphylococcus aureus by a component of tea (camellia sinensis): a study by electron microscopy.	a component of aqueous extracts of green tea (camellia sinensis), known to reverse methicillin-resistance in staphylococci, causes extensive morphological changes in methicillin-resistant but not in methicillin-sensitive staphylococcus aureus. clumps of partly divided cocci, consisting of up to 14 individuals, with thickened internal but normal external cell walls were seen by electron microscopy in cultures of methicillin-resistant s. aureus grown in the presence of the active principle. the mo ...	1999	10427729
mechanistic aspects of green tea as a cancer preventive: effect of components on human stomach cancer cell lines.	it is now well accepted that (-)-epigallocatechin gallate (egcg) inhibits carcinogenesis in the digestive tract in rodents. to understand the mechanisms of anticarcinogenesis, we first studied growth inhibition by egcg in human stomach cancer cell lines established at seoul national university (snu cell lines). inhibition by egcg of [3h]thymidine incorporation into eight snu cell lines was examined, in relation to transforming growth factor-beta (tgf-beta) responsiveness. various tea polyphenols ...	1999	10470285
inhibition of eleven mutagens by various tea extracts, (-)epigallocatechin-3-gallate, gallic acid and caffeine.	the antimutagenic properties of various tea extracts (green tea, pauchong tea, oolong tea and black tea) and their components including (-)-epigallocatechin-3-gallate (egcg), gallic acid and caffeine were examined by the ames test. the antimutagenic activity of the green tea extract against n-methyl-n'-nitro-n-nitrosoguanidine (mnng), folpet and monocrotophos was greater than those of pouchong, oolong and black tea extracts. the antimutagenic effects of tea extracts against 2-acetylaminofluorene ...	1999	10478825
inhibition of activator protein 1 activity and cell growth by purified green tea and black tea polyphenols in h-ras-transformed cells: structure-activity relationship and mechanisms involved.	ras gene mutation, which perpetually turns on the growth signal transduction pathway, occurs frequently in many cancer types. the mouse epidermal jb6 cell line has been transfected with a mutant h-ras gene to mimic carcinogenesis in vitro. these transformed cells (30.7b ras 12) are able to grow in soft agar, exhibiting anchorage independence and high endogenous activator protein 1 (ap-1) activity, which can be detected by a stable ap-1 luciferase reporter. the present study investigated the abil ...	1999	10493515
marked reduction in the minimum inhibitory concentration (mic) of beta-lactams in methicillin-resistant staphylococcus aureus produced by epicatechin gallate, an ingredient of green tea (camellia sinensis).	we found that epicatechin gallate, a constituent of an extract of tea leaves (green tea) markedly lowered the minimum inhibitory concentration (mic) of oxacillin and other beta-lactams, but not of other antibacterial agents tested, in strains of methicillin-resistant staphylococcus aureus. the antibacterial action of epicatechin gallate plus oxacillin was a bactericidal one.	1999	10746177
black tea increases the resistance of human plasma to lipid peroxidation in vitro, but not ex vivo.	a number of in vitro studies have shown that polyphenols and flavonoids in tea exert significant antioxidant activity. however, epidemiologic and experimental studies have produced conflicting results. the purpose of the present study was to compare the antioxidant activity of black tea in vitro with that ex vivo. black tea polyphenols (btp), black tea extract (bte), or their major polyphenolic antioxidant constituent, epigallocatechin gallate (egcg), were added to human plasma and lipid peroxid ...	1999	10468212
chemopreventive effects of tea extracts and various components on human pancreatic and prostate tumor cells in vitro.	pancreatic and prostate cancers pose serious problems to human health. to determine the potential for chemopreventive intervention against pancreatic and prostate cancers, black and green tea extracts and components of these extracts were examined in vitro for their effect on tumor cell growth. components included a mixture of polyphenols from green tea (gtp), mixtures of polyphenols (btp) and of theaflavins (mf) from black tea, and the purified components epicatechin-3-gallate (ecg) and epigall ...	1999	10624710
cancer chemopreventive mechanisms of tea against heterocyclic amine mutagens from cooked meat.	cooking meat and fish under normal conditions produces heterocyclic amine mutagens, several of which have been shown to induce colon tumors in experimental animals. in our search for natural dietary components that might protect against these mutagens, it was found that green tea and black tea inhibit the formation of heterocyclic amine-induced colonic aberrant crypt foci (acf) in the rat. since acf are considered to be putative preneoplastic lesions, we examined the inhibitory mechanisms of tea ...	1999	10202396
the prevention of lung cancer induced by a tobacco-specific carcinogen in rodents by green and black tea.	a growing body of evidence from studies in laboratory animals indicates that green tea protects against cancer development at various organ sites. we have previously shown that green tea, administered as drinking water, inhibits lung tumor development in a/j mice treated with 4-(methylnitrosamino)-1-(3-pyridyl)-l-butanone (nnk), a potent nicotine-derived lung carcinogen found in tobacco. the inhibitory effect of green tea has been attributed to its major polyphenolic compound, epigallocatechin g ...	1999	10202397
suppression of extracellular signals and cell proliferation by the black tea polyphenol, theaflavin-3,3'-digallate.	previous studies in our laboratory have shown that the major green tea polyphenol, (-)-epigallocatechin-3-gallate (egcg), suppressed autophosphorylation of epidermal growth factor (egf) receptor induced by egf in human a431 epidermoid carcinoma cells. in this study, we examined the inhibitory effects of black tea polyphenols, including theaflavin (tf-1), a mixture (tf-2) of theaflavin-3-gallate (tf-2a) and theaflavin-3'-gallate (tf-2b), theaflavin-3,3'-digallate (tf-3) and the thearubigin fracti ...	1999	10223207
inhibition of urinary bladder tumors induced by n-butyl-n-(4-hydroxybutyl)-nitrosamine in rats by green tea.	recently, the anticarcinogenic effects of green tea have been studied in sites other than the urinary tract. the present study examined the inhibition by green tea of vesical tumors induced in rats by n-butyl-n-(4-hydroxybutyl) nitrosamine (bbn).	1999	10226814
effects of chemoprotective agents on the metabolic activation of the carcinogenic arylamines phip and 4-aminobiphenyl in human and rat liver microsomes.	carcinogenic aromatic amines, including the heterocyclic amines, may pose a significant health risk to humans. to determine the potential for chemoprotective intervention against the carcinogenicity of these arylamines and to better understand their mechanism of action, a range of agents, most of them natural dietary constituents, was examined in vitro for their ability to modulate the n-hydroxylation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) and 4-aminobiphenyl (abp), an initial ...	1999	10227043
consumption of tea modulates the urinary excretion of mutagens in rats treated with iq. role of caffeine.	the present study was undertaken to investigate whether the consumption of green tea and black tea influences the excretion of mutagens and promutagens in rats treated orally with the food carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (iq). rats were maintained on aqueous extracts (2.5%, w/v) of green tea, black tea or decaffeinated black tea as their sole drinking liquid. after 4 weeks, the animals received, by gastric intubation, a single dose of iq (5 mg/kg), and urine was collected for ...	1999	10333533
teas and other beverages suppress d-galactosamine-induced liver injury in rats.	we compared the effects of various types of beverages (teas, coffee, and cocoa) on d-galactosamine-induced liver injury by measuring plasma alanine aminotransferase (alt) and aspartate aminotransferase (ast) activities in 7-wk-old male wistar rats. the effects of five fractions extracted with different organic solvents from green tea, different types of dietary fibers, and some short chain fatty acids were also investigated. all of the beverages tested significantly suppressed d-galactosamine-in ...	1999	10395599
antimutagenic and anticarcinogenic activity of tea polyphenols.	tea is the most popular beverage, consumed by over two thirds of the world's population. tea is processed differently in different parts of the world to give green (20%), black (78%) or oolong tea (2%). green tea is consumed mostly in japan and china. the antimutagenic and anticarcinogenic activities of green tea are extensively examined. the chemical components of green and black tea are polyphenols, which include ec, ecg, egc, egcg and tfs. this article reviews the epidemiological and experime ...	1999	9878691
antioxidant and eicosanoid enzyme inhibition properties of pomegranate seed oil and fermented juice flavonoids.	the antioxidant and eicosanoid enzyme inhibition properties of pomegranate (punica granatum) fermented juice and seed oil flavonoids were studied. the pomegranate fermented juice (pfj) and cold pressed seed oil (pcpso) showed strong antioxidant activity close to that of butylated hydroxyanisole (bha) and green tea (thea sinensis), and significantly greater than that of red wine (vitis vitifera). flavonoids extracted from pcpso showed 31-44% inhibition of sheep cyclooxygenase and 69-81% inhibitio ...	1999	10432202
chemoprevention studies of heterocyclic amine-induced colon carcinogenesis.	the cooking of meat and fish produces heterocyclic amine mutagens, including 2-amino-1-methyl-6-phenylimidazo[4,5b]pyridine (phip) and 2-amino-3-methylimidazo[4,5-f]quinoline (iq). chronic administration of phip or iq to the f344 rat induces tumors at several sites, including adenocarcinomas of the colon, and short-term treatment leads to the formation of colonic aberrant crypt foci (acf). we have used these end-points to identify potential chemopreventive agents that might be effective against ...	1999	10503900
proliferation of hepatic peroxisomes in rats following the intake of green or black tea.	rats maintained on green, black or decaffeinated black tea (2.5%, w/v) as their sole drinking fluid displayed higher hepatic cn- insensitive palmitoyl coa oxidase activity than controls; the extent of increase was similar with the three types of tea. morphological examination of the liver using electron microscopy revealed an increase in the number of peroxisomes in the tea-treated animals. the same treatment of the animals with green and black tea resulted in a similar rise in hepatic microsoma ...	1999	10514032
dietary fat, body weight, and cancer: contributions of studies in rodents to understanding these cancer risk factors in humans.	understanding diet and energy balance as risk factors for breast, colon, and other cancers requires information on the contribution of each factor and of interactions among factors to cancer risk. rodent models for breast cancer provide extensive data on effects of dietary fat and calories, energy balance, body weight gain, and physical activity on tumor development. analyses of the combined data from many studies have shown clearly that quality and quantity of dietary fat and energy balance con ...	1999	10630593
green tea in chemoprevention of cancer.	the concept of prevention of cancer using naturally occurring substances that could be included in the diet consumed by the human population is gaining increasing attention. tea, next to water, is the most popularly consumed beverage in the world and it is grown in about 30 countries. abundant data, amassed from several laboratories around the world in the last ten years, provided convincing evidence that polyphenolic antioxidants present in tea afford protection against cancer risk in many anim ...	1999	10630599
progress in cancer chemoprevention.	more than 40 promising agents and agent combinations are being evaluated clinically as chemopreventive drugs for major cancer targets. a few have been in vanguard, large-scale intervention trials--for example, the studies of tamoxifen and fenretinide in breast, 13-cis-retinoic acid in head and neck, vitamin e and selenium in prostate, and calcium in colon. these and other agents are currently in phase ii chemoprevention trials to establish the scope of their chemopreventive efficacy and to devel ...	1999	10668477
bioactive saponins and glycosides. xv. saponin constituents with gastroprotective effect from the seeds of tea plant, camellia sinensis l. var. assamica pierre, cultivated in sri lanka: structures of assamsaponins a, b, c, d, and e.	the saponin fraction from the seeds of the tea plant, camellia sinensis l. var. assamica pierre cultivated in sri lanka, was found to show a potent protective effect on gastric mucosal lesions induced by ethanol in rats. nine new acylated polyhydroxyoleanene-type triterpene oligoglycosides called assamsaponins a-i were isolated from the active saponin fraction together with three known saponins, theasaponin e1 and e2 and camelliasaponin b1. the structures of assamsaponins a-e were elucidated on ...	1999	10748719
inhibition of non-haem iron absorption in man by polyphenolic-containing beverages.	the effects of different polyphenol-containing beverages on fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-fe. the test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (matricaria recutita l.), vervain (verbena officinalis l.), lime flower (tilia cordata mill.), pennyroyal (mentha pulegium l.) and peppermint (mentha ...	1999	10999016
formation of antioxidants from (-)-epigallocatechin gallate in mild alkaline fluids, such as authentic intestinal juice and mouse plasma.	the oxidative dimerization of (-)-epigallocatechin gallate (egcg), the major catechin of tea leaves (camellia sinensis l.), in authentic intestinal juice (ph 8.5) and mouse plasma (ph 7.8) was investigated. egcg was unstable in the alkaline solutions over ph 7.4. the content of egcg was decreased to 19.4% and 60.7% at 5 minutes in the intestinal juice and plasma, respectively. three products-p-1 (theasinensin a), p-2 (a new dimerized product reported in a previous paper), and p-3 (theasinensin d ...	1999	15539294
modulation of hepatic cytochrome p450 activity and carcinogen bioactivation by black and decaffeinated black tea.	the principal objective of this study was to compare the ability of green, black and decaffeinated black tea to modulate hepatic expression of cytochromes p450 in the rat, and the consequences on the bioactivation of some food-borne carcinogens. furthermore, these studies allow inferences to be drawn as to the contribution of caffeine and flavanols in the tea-mediated changes in cytochrome p450 expression. black tea is prepared from fresh tea leaf following oxidation of flavanols by polyphenol o ...	1999	21781908
effects of green, oolong and black teas and related components on the proliferation and invasion of hepatoma cells in culture.	the effects of teas and related components on the proliferation and invasion of cancer cells were examined by employing both in vitro proliferation and invasion assay systems. powdered green, oolong and black tea extracts dose-dependently inhibited proliferation and invasion of a rat ascites hepatoma cell line of ah109a but did not affect the proliferation of the normal mesentery-derived mesothelial cells (m-cells) isolated from rats; higher concentrations of powdered oolong and black teas could ...	1999	19003122
role of polyphenol oxidase and peroxidase in the generation of black tea theaflavins.	it has been reported earlier that when macerated tea leaf is fermented at lower ph, the resultant black tea contains increased levels of theaflavin, an important quality marker in black tea. in an attempt to investigate the biochemistry and chemistry underlying this observation, in vitro oxidation experiments using polyphenol oxidase (ppo) from fresh tea leaves, horseradish peroxidase (pod), and tea catechins, precursors for theaflavins, were carried out. in vitro oxidation experiments using cru ...	1999	10552528
sickle cell anemia: a potential nutritional approach for a molecular disease.	a certain population of red blood cells in patients with sickle cell anemia has an elevated density and possesses an abnormal membrane. these "dense cells" have a tendency to adhere to neutrophils, platelets, and vascular endothelial cells, and, thus, they could trigger vasoocclusion and the subsequent painful crisis from which these patients suffer. we developed a laboratory method of preparing such dense cells and found that nutritional antioxidant supplements, hydroxyl radical scavengers, and ...	2000	10793299
antihemolytic effect of rooibos tea (aspalathus linearis) on red blood cells of japanese quails.	the antihemolytic activity of rooibos and black tea on japanese quail erythrocytes was studied. peroxide and hypotonic hemolysis of the red blood cells of quails, either fed with rooibos tea supplemented food or fed without tea, was performed. long-term consumption of rooibos tea did not change the erythrocyte fragility to either peroxide or hypotonia induced hemolysis. however, rooibos and black teas decreased peroxide induced hemolysis of erythrocytes incubated with each of them, but not hemol ...	2000	11409839
[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
antifungal activity of plant extracts against arthrinium sacchari and chaetomium funicola.	various plant extracts were examined for antifungal activity with the objective of improving the commercial sterility of aseptically filled tea beverage products in pet bottles. when the hot water extract and the methanol extract of 29 samples were measured for their antifungal activity against arthrinium sacchari m001 and chaetomium funicola m002 strains, five samples, acer nikoense, glycyrrhiza glabra, lagerstroemia speciosa, psidium guajava and thea sinensis, showed high activity. of these, t ...	2000	16232887
flavonoids protect against oxidative damage to ldl in vitro: use in selection of a flavonoid rich diet and relevance to ldl oxidation resistance ex vivo?	the ability of a range of dietary flavonoids to inhibit low-density lipoprotein (ldl) oxidation in vitro was tested using a number of different methods to assess oxidative damage to ldl. overall quercetin was the most effective inhibitor of oxidative damage to ldl in vitro. on this basis, a diet enriched with onions and black tea was selected for a dietary intervention study that compared the effect on the cu2+ ion-stimulated lag-time of ldl oxidation ex vivo in healthy human subjects of a high ...	2000	11022850
effects of black tea, green tea and wine extracts on intestinal carcinogenesis induced by azoxymethane in f344 rats.	we investigated whether polyphenolic extracts from black tea, green tea or red wine affect azoxymethane (aom)-induced intestinal carcinogenesis. male f344 rats were treated 10 times (1 week apart) with aom (7.4 mg/kg, s.c.) and then allocated into groups receiving black tea, green tea or red wine extracts mixed in the diet at a dose of 50 mg/kg body weight for 16 weeks. in the rats treated with black tea or wine extracts, there were significantly fewer colorectal tumours than in controls (the me ...	2000	11062155
protection against nitric oxide toxicity by tea.	it is found that green tea and black tea are able to protect against nitric oxide (no()) toxicity in several ways. both green tea and black tea scavenge no() and peroxynitrite, inhibit the excessive production of no() by the inducible form of nitric oxide synthase (inos), and suppress the lps-mediated induction of inos. the no() scavenging activity of tea was less than that of red wine. the high activity found in the polyphenol fraction of black tea (btp) could not be explained by the mixed ...	2000	11087552
acute effects of ingestion of black and green tea on lipoprotein oxidation.	tea has been associated with a reduced risk of cardiovascular disease. one proposed mechanism of this risk reduction involves inhibition of lipoprotein oxidation in vivo by antioxidant polyphenolic compounds derived from tea. however, controlled interventions uniformly failed to show that ingestion of tea can inhibit ldl oxidation ex vivo. the absence of effects in previous studies may be due to the isolation of ldl particles from polyphenolic compounds that are present in the aqueous phase of s ...	2000	10799371
electrospray characterization of selected medicinal plant extracts.	extracts of selected medicinal plants were examined by electrospray mass spectrometry (esi-ms). this technique allowed identification of the main components of each extract, thereby providing a typical finger-print of the examined plants. more specifically, anthocyanins (vaccinium myrtillus), isoflavones (glycine max, soybean), flavonol-glycosides and terpenes (ginkgo biloba), triterpenes (centella asiatica), caffeoyl-quinic acids (cynara scolymus, artichoke), ginsenosides (panax ginseng), catec ...	2000	10898155
protease from sporosarcina sp. rrlj 1.	protease was isolated from sporosarcina rrlj1 which was collected from acid tea (camellia sinensis) plantations. it showed potential for production of the enzyme for commercial purposes. the study revealed that optimum ph for growth of the organism was 6.5-7 and supplement of casein (1%) in the medium was required for production of protease. enzyme production and enzyme activity was maximum in 72 hr old broth culture. maximum activity of the enzyme was found at ph 6.5.	2000	10927879
correlation of chemopreventive efficacy data from the human epidermal cell assay with in vivo data.	continuous exposure to low doses of potentially mutagenic and carcinogenic chemicals over the human lifetime makes the identification of agents, which could reduce the ensuing risk of cancer, beneficial. the human epidermal cell (hec) assay includes multiple exposures to low, non-toxic doses of propane sultone, which increases cellular growth and inhibits differentiation, and co-exposure to potential chemopreventive agents to determine their ability to inhibit the increased growth or increase di ...	2000	10769631
inhibitory effects of tea extracts on the mutagenicity of 1-methyl-1, 2,3,4-tetrahydro-beta-carboline-3-carboxylic acid on treatment with nitrite in the presence of ethanol.	it has been shown that the mutagenicity of 1-methyl-1,2,3, 4-tetrahydro-beta-carboline-3-carboxylic acid (mtcca), a major mutagen precursor in soy sauce on treatment with nitrite and ethanol, was strongly decreased by the addition of hot water extracts of green, black and oolong teas in the reaction mixture when it was treated with 50mm nitrite at ph3.0, 37 degrees c for 60min in the presence of 7.5% ethanol. the mutagenicity-decreasing activity of the teas was scarcely decreased by washing the ...	2000	10685009
suppression of lipopolysaccharide-induced nuclear factor-kappab activity by theaflavin-3,3'-digallate from black tea and other polyphenols through down-regulation of ikappab kinase activity in macrophages.	we investigated the inhibition of ikappab kinase (ikk) activity in lipopolysaccharide (lps)-activated murine macrophages (raw 264.7 cell line) by various polyphenols including (-)-epigallocatechin-3-gallate, theaflavin, a mixture of theaflavin-3 gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate (tf-3), pyrocyanidin b-3, casuarinin, geraniin, and penta-o-galloyl-beta-d-glucose (5gg). tf-3 inhibited ikk activity in activated macrophages more strongly than did the other polyphenols. tf-3 ...	2000	10644043
kombucha, the fermented tea: microbiology, composition, and claimed health effects.	kombucha is a slightly sweet, slightly acidic tea beverage consumed worldwide, but historically in china, russia, and germany. kombucha is prepared by fermenting sweetened black tea preparations with a symbiotic culture of yeasts and bacteria. potential health effects have created an increased interest in kombucha. yet, only a few research studies have shown that kombucha has in vitro antimicrobial activity and enhances sleep and pain thresholds in rats. furthermore, kombucha consumption has pro ...	2000	10914673
effects of black tea extract on transplantable and solid tumors in swiss albino mice.	the chemopreventive effects of green tea and its polyphenols are well documented in the literature. epidemiological studies have suggested that green tea consumption might be effective in the prevention of certain human cancers. about 80% of the tea is consumed as black tea. limited studies have been carried out to assess the usefulness of black tea as anti-carcinogen. the present set of investigations were initiated to study the anti-tumorigenic potential of aqueous black tea extract (ate) in s ...	2000	11198223
novel approaches to chemoprevention of skin cancer.	protection against sun-induced damage leading to photocarcinogenesis in skin is a highly desirable goal. among various strategies, chemopreventive approaches utilizing non-toxic agents to prevent the occurrence of precancerous lesions or their surrogate markers are potentially attractive. epidemiological and experimental studies provide evidence that some naturally occurring chemical agents in the human diet can diminish cancer risk. aside from water, tea is the most common beverage consumed wor ...	2000	11138532
an approach to cancer risk assessment for the food constituent 2-hexenal on the basis of 1,n2-propanodeoxyguanosine adducts of 2-hexenal in vivo.	2-hexenal is formed by plants, and humans are regularly exposed to this mutagenic/genotoxic compound via vegetable foods. 2-hexenal has not been tested for carcinogenicity, but it forms exocyclic 1,n2-propanodeoxyguanosine adducts like other carcinogenic alpha,beta-unsaturated carbonyl compounds. to quantify the respective dna adducts as an approach to a theoretical cancer risk assessment, we used a newly developed 32p-postlabelling technique based on nuclease p1 enrichment, allowing a detection ...	2000	11201673
mechanisms of inhibition of carcinogenesis by tea.	tea (camellia sinensis) preparations have been shown to inhibit tumorigenesis at the initiation, promotion, and progression stages in different animal models. the anti-proliferative effects of tea polyphenols may be a key mechanism, especially in the nnk-induced lung tumorigenesis model with mice. studies with cell lines have demonstrated that tea polyphenols inhibit cell proliferation and induce apoptosis. the effective concentrations used in these studies (20-100 microm) are usually higher tha ...	2000	11237203
tea catechins and related polyphenols as anti-cancer agents.	epigallocatechin gallate (egcg) and theaflavins, a major constituent of green tea infusion and the constituents of black tea, respectively, were found to inhibit matrix metalloproteinases (mmps) which are intimately associated with tumor invasion and metastasis. egcg and related polyphenols exhibited apoptosis-inducing activity for several cancer cell lines including human stomach and colon cancer cells. comparison of the activity of these compounds revealed the importance of the number and the ...	2000	11237204
effect of dietary quercetin on oxidative dna damage in healthy human subjects.	the effect of dietary intake of flavonols (predominantly quercetin) on oxidative dna damage was studied in thirty-six healthy human subjects (sixteen men, twenty women). the study was a randomised crossover study, comprising two 14 d treatments of either a low-flavonol (lf) or high-flavonol (hf) diet with a 14 d wash-out period between treatments. subjects were asked to avoid foods containing flavonols, flavones and flavanols during the lf dietary treatment period and to consume one 150 g onion ...	2000	11177210
differential effects of theaflavin monogallates on cell growth, apoptosis, and cox-2 gene expression in cancerous versus normal cells.	theaflavin (tf-1), theaflavin-3-monogallate and theaflavin-3'-monogallate mixture (tf-2), and theaflavin-3,3'-digallate (tf-3) are the major black tea polyphenols. here we compared the effects of these polyphenols on cell growth, apoptosis, and gene expression in normal and cancerous cells. we showed that tf-2 (10-50 microm) inhibited the growth of sv40 transformed wi38 human cells (wi38va) and caco-2 colon cancer cells but had little effect on the growth of their normal counterparts. the ic50s ...	2000	11103814
effect of black tea on lipid peroxide and glutathione levels in female rats.	the effects of black tea (camellia sinensis l.) on lipid peroxidation and glutathione (gsh) levels in carbon tetrachloride (ccl4)-treated female wistar rats were examined. two control groups and one treatment group were tested. the control groups were fed with a standard diet, while the black tea group was fed the standard diet plus 6% by weight dried black tea leaves. at the end of 2 months, a single dose of ccl4 (1 ml/kg, i.p.) in olive oil was administered to rats in one of the control groups ...	2000	11201308
synergistic effects of thearubigin and genistein on human prostate tumor cell (pc-3) growth via cell cycle arrest.	there is evidence that habitual consumption of green tea by japanese men is correlated with a reduction in cancers, including prostate; soybean isoflavones are also associated with increased protection. the present study compared the anti-proliferative effect of black tea (camellia sinensis) polyphenol, thearubigin (tr), alone or combined with the isoflavone genistein, on human prostate (pc-3) carcinoma cells. tr administered alone did not result in any alteration of cell growth. when combined w ...	2000	10766429
inactivation of human type a and b influenza viruses by tea-seed saponins.	the effects of a mixture of tea-seed saponins obtained from the seeds of camellia sinensis var. sinesis on human influenza viruses types a and b were investigated. at the concentrations of 60, 80, and 100 micrograms/ml, respectively, the mixture inactivated viruses a/memphis/1/71 (h3n2), b/lee/40, and a/pr/8/34 (h1n1) almost completely. the mixture also inactivated type a virus a/pr/8/34 after inoculation at concentrations of 1-30 micrograms/ml dose-dependently.	2000	10705466
inhibition of human ldl lipid peroxidation by phenol-rich beverages and their impact on plasma total antioxidant capacity in humans.	mounting evidence shows that phenol-rich beverages exert strong antioxidant activity. however, in vivo evidence has produced conflicting results. in the present study, we studied the impact of the ingestion of 300 ml of black and green tea, alcohol-free red wine, alcohol-free white wine, or water on plasma total antioxidant capacity in five healthy volunteers. red wine has the highest content of phenolics (3.63 +/- 0.48 g qe/l), followed by green tea (2.82 +/- 0.07 g qe/l), black tea (1.37 +/- 0 ...	2000	11137897
prokinetic effect of black tea on gastrointestinal motility.	the gastrokinetic effects of hot water extract of black tea [camellia sinensis, (l) o. kuntze (theaceae)] on gastrointestinal motility were studied both in vivo and in vitro. the extract significantly accelerated the gastrointestinal transit (git) in vivo in mice. these facilitatory effect was reduced after pretreatment with atropine, hemicholinium-3, morphine, indomethacin, mcn-a-343 and l-arginine. in guinea pig ileum, the extract facilitated the peristaltic reflex in response to pressures in ...	2000	10698359
tea and tea polyphenols in cancer prevention.	the inhibitory action of tea (camellia sinensis) and tea components against cancer formation has been demonstrated in different animal models involving different organ sites in many laboratories. the possible preventive activity of tea against cancer in humans, however, is not clear. a critical question is whether the information obtained from animal studies is applicable to humans because of possible species differences or the difference in the quantity of tea used in animal studies and that co ...	2000	10721932
insulin-like biological activity of culinary and medicinal plant aqueous extracts in vitro.	to evaluate the possible effects on insulin function, 49 herb, spice, and medicinal plant extracts were tested in the insulin-dependent utilization of glucose using a rat epididymal adipocyte assay. cinnamon was the most bioactive product followed by witch hazel, green and black teas, allspice, bay leaves, nutmeg, cloves, mushrooms, and brewer's yeast. the glucose oxidation enhancing bioactivity was lost from cinnamon, tea, witch hazel, cloves, bay leaf and allspice by poly(vinylpyrrolidone) (pv ...	2000	10725162
cancer chemoprevention by tea polyphenols.	tea is one of the most widely consumed beverages, second only to water. many experimental researches in laboratory animals demonstrated that tea components had an inhibitory effect on carcinogenesis at a number of organ sites. the inhibitory effects of tea against carcinogenesis have been attributed to the biologic activities of the polyphenol fraction in tea. this review summarizes experimental data on chemopreventive effects of tea polyphenols in various tumor bioassay systems. many laboratory ...	2000	10786933
tea as a potential chemopreventive agent in phip carcinogenesis: effects of green tea and black tea on phip-dna adduct formation in female f-344 rats.	the heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) is formed during the cooking of proteinaceous animal foods (meat, chicken, and fish). phip is a carcinogen in the fischer 344 (f-344) rat; it induces mammary tumors in female rats and lymphomas and colon and prostate tumors in male rats. in f-344 rats, phip forms dna adducts in various organs, including the target organs. inhibition of phip-dna adduct formation is likely to lead to inhibition of phip tumorigenicity. we ...	2000	10798216
catechin contents of foods commonly consumed in the netherlands. 2. tea, wine, fruit juices, and chocolate milk.	catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. to enable an epidemiological evaluation of catechins, data on their contents in foods are required. hplc with uv and fluorescence detection was used to determine the levels of (+)-catechin, (-)-epicatechin, (+)-gallocatechin (gc), (-)-epigallocatechin (egc), (-)-epicatechin gallate (ecg), and (-)-epigallocatechin gallate (egcg) in 8 types of black tea, 18 types of red and white wines, apple juice ...	2000	10820090
comparative study of antioxidant potential of tea with and without additives.	oxidative damage is one of the many mechanism leading to chronic diseases. therefore interest is growing in the protection afforded by antioxidant nutrients against free radical reactions. more recently, the attention has shifted to polyphenols. polyphenols are secondary plant metabolites occurring widely in plant food. they possess outstanding antioxidant properties, suggesting a possible protective role in man. tea (camellia sinensis) is a widely consumed beverage throughout the world containi ...	2000	10846639
tea intake and squamous cell carcinoma of the skin: influence of type of tea beverages.	differences in tea drinking habits are likely to vary by populations and could contribute to the inconsistencies found between studies comparing tea consumption and cancer risk. a population-based case-control study was used to evaluate how usual tea consumption patterns of an older population (n = 450) varied with history of squamous cell carcinoma (scc) of the skin. a detailed tea questionnaire was developed to assess specific tea preparation methods and patterns of drinking. in this southwest ...	2000	10919744
inhibitory effects of tea catechins and o-methylated derivatives of (-)-epigallocatechin-3-o-gallate on mouse type iv allergy.	the inhibitory effects of tea catechins, the o-methylated derivatives of (-)-epigallocatechin-3-o-gallate (egcg), and the polyphenol extracts from tea leaves (camellia sinensis l.) on oxazolone-induced type iv allergy in male icr mice were investigated. four major tea catechins and two o-methylated derivatives, (-)-epigallocatechin-3-o-(3-o-methyl)gallate (egcg3' 'me) and (-)-epigallocatechin-3-o-(4-o-methyl)gallate (egcg4' 'me), showed significant inhibitory effects on mouse type iv allergy aft ...	2000	11087533
inhibition of 1,2-dimethylhydrazine-induced oxidative dna damage in rat colon mucosa by black tea complex polyphenols.	the effect of black tea polyphenols on 1,2-dimethylhydrazine (dmh)-induced oxidative dna damage in rat colon mucosa has been investigated. fischer 344 rats were treated orally with thearubigin (tr) or theafulvin (tfu) for 10 days (40 mg/kg), injected ip with dmh (20 mg/kg) or saline and sacrificed 24 hr after dmh administration. the levels of 8-hydroxy-2'-deoxyguanosine (8-ohdg) were measured in colonic mucosa dna and expressed as a ratio relative to 2'-deoxyguanosine (2dg). control rat mucosa h ...	2000	11033196
effect of black and green tea polyphenols on c-jun phosphorylation and h(2)o(2) production in transformed and non-transformed human bronchial cell lines: possible mechanisms of cell growth inhibition and apoptosis induction.	the biological activities of theaflavin (tf), theaflavin gallate (tfg) and theaflavin digallate (tfdig) from black tea and (-)-epigallocatechin 3-gallate (egcg) and (-)-epigallocatechin (egc) from green tea were investigated using sv40-immortalized (33bes) and ha-ras gene transformed (21bes) human bronchial epithelial cell lines. growth inhibition and cell viability were measured by trypan blue dye exclusion assay following 24 h treatment with the tea polyphenols. tfdig, egc and egcg displayed c ...	2000	11062165
tea polyphenols: prevention of cancer and optimizing health.	the tea plant camellia sinesis is cultivated in >30 countries. epidemiologic observations and laboratory studies have indicated that polyphenolic compounds present in tea may reduce the risk of a variety of illnesses, including cancer and coronary heart disease. most studies involved green tea, however; only a few evaluated black tea. results from studies in rats, mice, and hamsters showed that tea consumption protects against lung, forestomach, esophagus, duodenum, pancreas, liver, breast, colo ...	2000	10837321
comparative chemopreventive mechanisms of green tea, black tea and selected polyphenol extracts measured by in vitro bioassays.	black tea extracts (hot aqueous, polyphenols and theaflavins) and green tea extracts (hot aqueous, polyphenols, epicatechin, epicatechin gallate, epigallocatechin and epigallocatechin gallate) were tested in nine standardized cell culture assays for comparative cancer chemopreventive properties. most black and green tea extracts strongly inhibited neoplastic transformation in mouse mammary organ cultures, rat tracheal epithelial cells and human lung tumor epithelial cells. nearly all tea fractio ...	2000	10607735
induction of apoptosis by the oolong tea polyphenol theasinensin a through cytochrome c release and activation of caspase-9 and caspase-3 in human u937 cells.	this study examined the growth inhibitory effects of theasinensin a (from oolong tea) and black tea polyphenols, including theaflavin (tf-1), a mixture (tf-2) of theaflavin-3-gallate (tf-2a) and theaflavin-3'-gallate (tf-2b), and theaflavin-3,3'-digallate (tf-3) in human cancer cells. theasinensin a, tf-1, and tf-2 displayed strong growth inhibitory effects against human histolytic lymphoma u937, with estimated ic50 values of 12 microm, but were less effective against human acute t cell leukemia ...	2000	11312805
determination of total aluminum, chromium, copper, iron, manganese, and nickel and their fractions leached to the infusions of black tea, green tea, hibiscus sabdariffa, and ilex paraguariensis (mate) by eta-aas.	total aluminum, chromium, copper, iron, manganese, and nickel were determined in black tea, green tea, hibiscus sabdariffa, and ilex paraguariensis (mate) by electrothermal atomic absorption spectrometry after nitric/perchloric acid digestion. in each case, one ground sample of commercially available leafy material was prepared and three 0.5-g subsamples were run in parallel. the infusions were also analyzed and the percentage of each element leached into the liquor was evaluated. the obtained r ...	2000	11314985
induction of apoptosis and cell cycle arrest in cancer cells by in vivo metabolites of teas.	the present study was conducted to determine in vivo possibilities of inducing apoptosis and cell cycle arrest in rat cancer cells by green, oolong, and black teas and also to further identify the mechanisms inhibiting cancer cell proliferation by the sera from tea-treated rats. the tea extracts from these three kinds of tea, the rat sera obtained after oral intubation of the tea extracts, and the tea polyphenolic compounds, (-)-epigallocatechin-3-gallate, (-)-epigallocatechin, (-)-epicatechin-3 ...	2000	11525605
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
inhibition of ultraviolet b-induced ap-1 activation by theaflavins from black tea.	theaflavins are believed to be key active components in black tea for chemoprevention of cancer. however, the molecular mechanisms underlying the inhibitory effects of theaflavins are not clear. with the jb6 mouse epidermal cell line, we investigated the effects of theaflavins on ultraviolet (uv) b radiation-induced activator protein-1 (ap-1)-dependent transcriptional activation and compared them with (-)-epigallocatechin-3-gallate (egcg), a major green tea polyphenol that has cancer chemopreven ...	2000	10942531
green tea.	tea is one of the most widely consumed beverages in the world today, second only to water, and its medicinal properties have been widely explored. the tea plant, camellia sinensis, is a member of the theaceae family, and black, oolong, and green tea are produced from its leaves. it is an evergreen shrub or tree and can grow to heights of 30 feet, but is usually pruned to 2-5 feet for cultivation. the leaves are dark green, alternate and oval, with serrated edges, and the blossoms are white, frag ...	2000	10956382