| tea and cancer prevention: an evaluation of the epidemiologic literature. | animal and in vitro studies provide evidence of an anticarcinogenic potential of active ingredients in teas. this review encompasses epidemiologic studies of stomach, colon, and lung cancer as well as the evidence of a relationship between tea drinking and cancer at large in humans. cohort studies do not suggest a protective role for tea drinking in the total risk of cancer. site-specific studies reveal a more complex picture. the epidemiologic studies on tea drinking and stomach cancer do not j ... | 1997 | 8970175 |
| fungicidal and insect controlling properties of proteus strain rrlj 16, isolated from tea, camellia sinensis (l) o kuntze, plantations. | a strain of proteus rrlj 16, isolated from acid (ph 4.5-5.5) iron rich tea (camellia sinensis) plantation soil, produced siderophores with single absorption peak at 370 nm when cultured in iron free medium. extracted crude fraction of siderophores and live cultures showed in vitro antibiosis against five species of pathogenic fungi. when the strain was cultured in a normal bacteriological medium without iron stress, it produced an insect repellent compound. the culture filtrate sprayed (dilution ... | 1996 | 8979512 |
| [effect of tea-leaf saponin on blood pressure of spontaneously hypertensive rats]. | the antihypertensive effect of tea-leaf saponin (the saponin mixture isolated from leaves of camellia sinensis var. sinensis) was examined in spontaneously hypertensive rats (shr). tea-leaf saponin reduced a time-dependent increase in blood pressure dose-dependently when it was administered orally to young shr (7 weeks old) for 5 d. oral administration of tea-leaf saponin to elder shr (15 weeks old) for 5 d decreased the mean blood pressure by 29.2 mmhg at the dose of 100mg/kg compared to the co ... | 1996 | 9019528 |
| comparison of metabolic effects of vegetables and teas with colorectal proliferation and with tumour development in dmh-treated f344 rats. | the aim of this study was to screen potentially chemopreventive vegetables and teas for their effects as human dietary components for the colorectal epithelium and also to seek biomarkers of preventive efficacy. groups of f344 rats were adapted to a human basal diet supplemented with vegetables or teas, having known contents of glucosinolates, polyphenols and anti-oxidants. both inductions and suppressions were found for overall glutathione s-transferase (gst) and quinone reductase activities. t ... | 1997 | 9103311 |
| tea, or tea and milk, inhibit mammary gland and colon carcinogenesis in rats. | research was performed on the effect of tea, or tea and milk, instead of drinking water, in rat models of cancer in the mammary gland or colon. solutions of 1.25% (w/v) black tea, or 1.85% (v/v) milk in tea were prepared three times per week. sd rats were given tea beginning at 42 days of age; one group was gavaged 5 mg 7,12-dimethylbenz[a]anthracene (dmba) at 49 days of age; another group received 8.4 mg 2-amino-3-methylimidazo[4,5-f]quinoline (iq) twice per week beginning at age 49, then 14 mg ... | 1997 | 9103322 |
| characterization of early pulmonary hyperproliferation and tumor progression and their inhibition by black tea in a 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis model with a/j mice. | the pathogenesis of pulmonary tumors induced by a tobacco carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk), and its inhibition by black tea have been characterized. female a/j mice (6 weeks old) were treated with a single dose of nnk (103 mg/kg of body weight, i.p.) on day 0, and the cell proliferation index was measured by the incorporation of bromodeoxyuridine (brdurd) immunohistochemically. the number of brdurd-labeled cells increased in the bronchiolar epithelium from day 2 t ... | 1997 | 9157981 |
| herbal teas and populace health care in tropical china. | commercial chinese herbal tea is the development of the populace in tropical and subtropical china consequential to their fight against infectious diseases and their struggle to explore local plants to relieve fever, to alleviate pain, to restore strength and to modulate immunity against viral epidemics. from these ethnomedical experiences, two types of herbal teas were commercialized, namely, liangcha and medicated teas. liangcha refers to a ready-made decoction infused from wild plants served ... | 1997 | 9167003 |
| anti-allergic effect of tea-leaf saponin (tls) from tea leaves (camellia sinensis var. sinensis). | we investigated the anti-allergic effect of tea-leaf saponin (tls), which was a mixture of saponins separated from the leaves of camellia sinensis var. sinensis, in guinea pigs and rats. tls (20-100 mg/kg) dose-dependently inhibited experimentally-induced asthma, and id50 was 61.7 mg/kg. tls (20-100 mg/kg) dose-dependently inhibited a 48 h homologous pca (passive cutaneous anaphylaxis) reaction, and the inhibitory effect was similar to that of tranilast. tls (1-100 microg/ml) also inhibited the ... | 1997 | 9178940 |
| chemoprotection against the formation of colon dna adducts from the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) in the rat. | the mutagenic heterocyclic aromatic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip), is a pyrolysis product in cooked foods that has been shown to be a rat colon carcinogen and has been implicated in the etiology of human colon cancer. in order to identify chemoprotection strategies that could be carried out in humans, a pilot study was conducted in which phip-dna-adduct levels were quantified in the colons of male f344 rats that had been subjected to 16 different putative chemopro ... | 1997 | 9202746 |
| anti-human immunodeficiency virus activity of oligosaccharides from rooibos tea (aspalathus linearis) extracts in vitro. | the active substances, acid polysaccharides, were extracted with 1% sodium hydroxide from the leaves of rooibos tea (aspalathus linearis), du zhong cha (eucommia ulmoides oliv.) and japanese tea leaves (camellia sinensis var. sinensis). the alkaline extracts of rooibos tea and du-zhong tea leaves, but not japanese tea leaves suppressed the hiv-induced cytopathicity using hiv (htlv-iii) infected mt-4 cells, having extremely low cytotoxicity: its 50% effective concentration (ec50) was 12-67 microg ... | 1997 | 9209319 |
| microbiological activity of whole and fractionated crude extracts of tea (camellia sinensis), and of tea components. | aqueous extracts of teas (camellia sinensis) of different types and from various sources inhibited a wide range of pathogenic bacteria, including methicillin-resistant staphylococcus aureus. tea extracts were bactericidal to staphylococci and yersinia enterocolitica at well below 'cup of tea' concentrations. activity was confined to one of four fractions obtained from a green tea extract by partition chromatography. testing of pure tea compounds and closely related chemicals suggested that the a ... | 1997 | 9228784 |
| [prophylactic effect of black tea extract as gargle against influenza]. | we examined whether gargling with black tea prevents influenza infection. tests were carried out during a five month period (october 1992 to march 1993). the control group that followed their normal daily routine, whereas the test group that gargled with 0.5 w/v% black tea extract twice daily (at 8 a.m. and 5 p.m.). influenza viruses were isolated from influenza patients and an antigen analysis was carried out. as a result, two strains of influenza a viruses (h3n2) and ten strains of b virus wer ... | 1997 | 9248263 |
| polyphenols as inhibitors of carcinogenesis. | many polyphenolic compounds have demonstrated anticarcinogenic activities in animal models. these compounds include flavanone, flavonols, isoflavone, and catechins. in this article, tea catechins will be used as an example to illustrate current research in this area. many laboratory studies have demonstrated the inhibition of tumorigenesis in animal models by different tea preparations. the animal models include tumorigenesis in the mouse lung, rat and mouse esophagi, mouse forestomach, mouse sk ... | 1997 | 9255589 |
| [effect of tea extracts, catechin and caffeine against type-i allergic reaction]. | the antiallergic effects of green tea, oolong tea, and black tea extracts by hot water were examined. these extracts inhibited the passive cutaneous anaphylaxis (pca) reaction of rat after oral administration. three tea catechins, (--)-epigallocatechin (egc), (--)-epicatechin gallate (ecg), and (--)-epigallocatechin gallate (egcg) isolated from green tea showed stronger inhibitory effects than that of a green tea extract on the pca reaction. the inhibitory effects of egc and egcg on the pca reac ... | 1997 | 9261215 |
| inhibitory activity of green and black tea in a free radical-generating system using 2-amino-3-methylimidazo[4,5-f]quinoline as substrate. | green tea and black tea inhibit colon carcinogenesis in rats exposed to the cooked meat mutagen 2-amino-3-methylimidazo[4,5-f]quinoline (iq). in the present investigation, green tea, black tea and (-)-epigallocatechin gallate (egcg) were shown to block the production of oxygen free radicals derived from iq in the presence of nadph-cytochrome p450 reductase. in kinetic studies using iq as the substrate and dmpo as a free radical spin trap, egcg increased the k(m) of the reaction without altering ... | 1997 | 9263532 |
| effect of green tea (camellia sinensis) extract on the rat diaphragm. | the effect of hot water extract of green tea on skeletal muscle and its neurotransmission was studied employing innervated and denervated rat diaphragm. green tea extract (gte) has a facilitatory effect at lower concentrations and a paralytic effect at higher concentrations on skeletomotor function. gte did not have any effect on direct twitch responses or on acetylcholine (ach) and kcl induced contractures of denervated rat diaphragm and it antagonised the submaximal paralytic effect of d-tuboc ... | 1997 | 9292413 |
| effects of dietary consumption of black tea infusion alone and in combination with known clastogens on mouse bone marrow chromosomes in vivo. | black tea infusion in water, in concentrations simulating human consumption, was administered by gavage daily to male swiss mice for 7 days. one set was given tea once daily and the other twice daily. the mice were then exposed to two known clastogens: chromium (vi) as potassium dichromate and mitomycin c on day 7, and killed after 24 hr. chromosome damage was studied in preparations made from bone marrow following colchine injection of all mice, and examination of the cells after pretreatment i ... | 1997 | 9301648 |
| theophylline metabolism in higher plants. | metabolism of [8-(14)c]theophylline was investigated in leaf segments from camellia sinensis (tea), camellia irrawadiensis, ilex paraguariensis (maté) and avena sativa, root segments of vigna mungo seedlings and cell suspension cultures of catharanthus roseus. there was extensive uptake and metabolism of [8-(14)c]theophylline by leaves of tea and camellia irrawadiensis and, to a lesser extent, maté. these purine alkaloid-containing species converted [8-(14)c]theophylline into 3-methylxanthine, x ... | 1997 | 9305805 |
| inhibition of collagenases from mouse lung carcinoma cells by green tea catechins and black tea theaflavins. | theaflavin and theaflavin digallate, which are components of black tea were examined by in vitro invasion assay with mouse lewis lung carcinoma ll2-lu3 cells, which are highly metastatic. the compounds inhibited invasion by the tumor cells. gelatin zymography showed that the cells secreted matrix metalloproteinases (mmps), probably including mmp-2 and mmp-9, which may be involved in tumor cell invasion and metastasis. theaflavin and theaflavin digallate also inhibited mmps from the culture mediu ... | 1997 | 9339552 |
| some perspectives on dietary inhibition of carcinogenesis: studies with curcumin and tea. | topical application of curcumin inhibits chemically induced carcinogenesis on mouse skin, and oral administration of curcumin inhibits chemically induced oral, forestomach, duodenal, and colon carcinogenesis. curcumin and other inhibitors of cyclooxygenase and lipoxygenase are thought to inhibit carcinogenesis by preventing the formation of arachidonic acid metabolites. in contrast to our expectation of a tumorigenic effect of arachidonic acid, we found that treatment of 7,12-dimethylbenz[a]anth ... | 1997 | 9349692 |
| possible mechanisms of antimutagens by various teas as judged by their effects on mutagenesis by 2-amino-3-methylimidazo[4,5-f]quinoline and benzo[a]pyrene. | possible mechanisms of antimutagenicity of various tea extracts (green, pouchong, oolong and black tea) toward 2-amino-3-methylimidazo[4,5-f]quinoline (iq) and benzo[a]pyrene (b[a]p) were investigated using a salmonella/microsome assay. tea extracts exhibited no inhibitory effects toward iq and b[a]p in bio-antimutagenic assays, indicating that their antimutagenic activity is desmutagenic in nature. the mutagenicities of iq and b[a]p decreased as the reaction periods of tea extracts with promuta ... | 1997 | 9357568 |
| urine levels of aluminum after drinking tea. | a microwave-assisted acid digestion procedure coupled with a graphite furnace atomic absorption method has been applied in the determination of aluminum (al) in urine to verify the correlation of free forms of al in tea infusions and urinary excretion of al. significant urinary al excretion has been found in 24-h urine of four volunteers after tea drinking. however, the difference in amount of al excretion in urine between the consumption of oolong (black tea) and long-jin (green tea), each of t ... | 1997 | 9359993 |
| inhibition of phorbol ester tumor promoter 12-o-tetradecanoylphorbol-13-acetate-caused inflammatory responses in sencar mouse skin by black tea polyphenols. | over the past 10 years many studies from several laboratories defined anticarcinogenic and anti-inflammatory effects of tea, a widely consumed beverage by the human population. much of such work has been conducted with green tea or its polyphenolic constituents. regarding black tea, studies have shown that its water extract affords protection against tumor promotion caused by chemical carcinogens or ultraviolet b radiation in murine skin carcinogenesis models. several studies have shown that top ... | 1997 | 9363999 |
| effects of theaflavins on n-nitrosomethylbenzylamine-induced esophageal tumorigenesis. | the purpose of this experiment was to compare the inhibitory effects of the polyphenol fraction of black tea, theaflavins (tf), the polyphenol fraction of green tea, and (-)-epigallocatechin-3-gallate (egcg) in the rat esophageal tumor model. the tea fractions were administered in the drinking water at concentrations of 360 and 1,200 ppm for two weeks before administration of the esophageal carcinogen n-nitrosomethylbenzylamine (nmba). nmba was administered subcutaneously in 10% dimethyl sulfoxi ... | 1997 | 9383778 |
| inhibitory effect of black tea on the growth of established skin tumors in mice: effects on tumor size, apoptosis, mitosis and bromodeoxyuridine incorporation into dna. | female cd-1 mice were initiated with a single topical application of 7,12-dimethylbenz[a]anthracene and promoted with 12-o-tetradecanoylphorbol-13-acetate. mice with established papillomas were then treated with black tea or decaffeinated black tea (approximately 4 mg tea solids/ml) as the sole source of drinking fluid for 11-15 weeks. in four separate experiments, oral administration of black tea inhibited the growth of papillomas (increase in tumor volume/mouse) by an average of 35%, 37%, 41% ... | 1997 | 9395217 |
| effects of green tea, black tea and dietary lipophilic antioxidants on ldl oxidizability and atherosclerosis in hypercholesterolaemic rabbits. | the hypothesis that tea or dietary lipid-soluble antioxidants reduce atherogenesis by lowering the oxidizability of low-density lipoprotein (ldl) was investigated. five groups of 20 female new zealand white rabbits were fed a restricted amount of a high-fat (30 en%) semipurified diet supplemented with cholesterol (0.15%, w/w) for 21 weeks. the vitamin e content of the control diet was 40 mg/kg diet. the animals received either green tea or black tea in their drinking water or vitamin e (200 mg/k ... | 1997 | 9395271 |
| microbiological screening of indian medicinal plants with special reference to enteropathogens. | the world health organisation (who) has recommended that all member states actively promote native medicines in their country. ten indian medicinal plants were screened for antibacterial activity specific to enteropathogens. diffusion and dilution methods were used to measure the antibacterial activity. allium sativum, camellia sinensis, and chamaesyce hirta showed higher activity when compared to the rest. they had a minimum bactericidal concentration (mbc) of < 100 micrograms/ml and gave inhib ... | 1997 | 9395690 |
| effects of tea and chlorophyllin on the mutagenicity of n-hydroxy-iq: studies of enzyme inhibition, molecular complex formation, and degradation/scavenging of the active metabolites. | green tea and black tea inhibit the formation of carcinogen-dna adducts and colonic aberrant crypts in rats given 2-amino-3-methylimidazo[4, 5-f]quinoline (iq), a mutagen from cooked meat. the salmonella mutagenicity assay was used in the present study to test individual constituents of tea as inhibitors of 2-hydroxyamino-3-methylimidazo[4, 5-f]quinoline (n-hydroxy-iq), a direct-acting metabolite of iq. testing of pure compounds at doses relevant to their levels in tea identified epigallocatechi ... | 1997 | 9435888 |
| inhibition of carcinogenesis by tea: the evidence from experimental studies. | in its various forms, tea is one of the most widely consumed beverages in the world. elucidation of the chemical components of tea has revealed that the beverage is a rich repository of antioxidants. among these are the polyphenolics, common to green tea, but also found in black teas together with oxidized polymers that in part account, for the darkened color. consumption of tea on a regular basis has been associated with reduced risk of several forms of cancer in human populations, with the str ... | 1997 | 9447274 |
| black tea constituents, theaflavins, inhibit 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk)-induced lung tumorigenesis in a/j mice. | the present study investigated the inhibitory activity against lung tumorigenesis by a group of characteristic black tea polyphenols, theaflavins. in a short-term study, female a/j mice were treated with a single dose of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk; 103 mg/kg b.w., i.p.) on day 0, and 0.1 and 0.3% theaflavins were administered as the sole source of drinking fluid starting 24 h after nnk treatment. the proliferation index of the lung tissues was measured by the incorporati ... | 1997 | 9450482 |
| [comparison between black tea and gargles on inhibition of the infectivity of influenza virus]. | | 1997 | 9455060 |
| screening of potential cancer preventing chemicals for induction of glutathione in rat liver cells. | with brl 3a hepatocytes, a series of selected, potentially chemopreventive chemicals was evaluated for their capacity to elevate glutathione (gsh) levels. since sodium selenite consistently increased gsh levels by approximately 70%, it was selected as a positive control. of 62 test chemicals, eighteen stimulated gsh levels by >30%, but eleven of these had only a modest effect or displayed considerable toxicity. at non-toxic concentrations, seven compounds had substantial activity: black tea extr ... | 1998 | 9468590 |
| effect of black tea on azoxymethane-induced colon cancer. | two sets of experiments on the role of tea in azoxymethane (aom) induced colon cancer were performed. the first test involved male f344 rats given 1.25% solutions of black tea beginning at 5 weeks of age and ending at 51 days of age. at 6 and 7 weeks of age, they received 15 mg/kg aom and were held for 50 weeks. another group received the aom dosage at 6 and 7 weeks and were placed on the tea solutions 2 days after the last aom dosage, at 51 days of age, and held for the 50-week period. the end ... | 1998 | 9472717 |
| potent suppressive activity of nonpolyphenolic fraction of green tea (camellia sinensis) against genotoxin-induced umu c gene expression in salmonella typhimurium (ta 1535/psk 1002), tumor promotor-dependent ornithine decarboxylase induction of balb/c 3t3 fibroblast cells, and chemically induced mouse skin tumorigenesis. | many experimental studies for anticarcinogenic activity of green tea (camellia sinensis) and tea-derived polyphenols have been carried out. however, the anticarcinogenic activity of the nonpolyphenolic fraction of green tea has been poorly elucidated. to study this problem, the effect of the nonpolyphenolic fraction of green tea leaves was analyzed using in vitro and in vivo experiments associated with tumor initiation and promotion as follows: 1) the nonpolyphenolic fraction caused a strong sup ... | 1997 | 9485539 |
| effects of japanese black tea on atherosclerotic disorders. | the atherogenic index was found to be significantly better in rats fed a high-cholesterol diet supplemented with black tea extract than in the ones not given the extract. it was also evident that black tea inhibited the proliferation of smooth muscle cells involved in the development and progression of atherosclerosis, and suppressed the production of oxidized low-density lipoprotein, a cause of lipid accumulation. it thus seems likely that black tea has an antiatherosclerotic action. | 1998 | 9501517 |
| inhibition of n-nitrosation of secondary amines in vitro by tea extracts and catechins. | inhibition of nitrite-mediated n-nitrosation of dimethylamine, morpholine and n-methylaniline by tea extracts and by 6 individual catechins in the extracts was studied. the inhibitions were detected by quantifying the nitrosamines formed. eight different kinds of teas (5 green teas, a roasted green tea, an oolong tea, and a black tea) were examined for their inhibitory abilities and for their catechin contents, with an attempt to correlate the inhibitory activities to the catechin contents. the ... | 1998 | 9508368 |
| effect of tea on the formation of dna adducts by azoxymethane. | 1. the effect of black tea on the conversion of azoxymethane (aom) to dna reactive metabolites was studied in four groups of the male f344 rat. each received 1.25% solutions of tea for 2 or 6 weeks, and simultaneous controls drank water. all rats were injected s.c. twice with 15 mg/kg aom after the first or fifth week respectively, on tea or water, and again 1 week later. groups were killed 6 h after the last dose, or 18 h later. the liver and colon were rapidly removed and rinsed with buffer so ... | 1998 | 9522444 |
| inhibition of spontaneous formation of lung tumors and rhabdomyosarcomas in a/j mice by black and green tea. | we investigated the effects of black tea (bt) and green tea (gt) infusion on the spontaneous formation of lung tumors and rhabdomyosarcomas in a/j mice. female a/j mice, 6 weeks of age, were allocated into five groups (50 per group) and were given the following as the sole source of drinking fluid: (i) deionized water (control group), (ii) 0.5% bt, (iii) 1% bt, (iv) 2% bt and (v) 1% gt. after 60 weeks, the mice were killed by decapitation. lung tumor incidence, multiplicity and volume were signi ... | 1998 | 9525286 |
| protective role of black tea against oxidative damage of human red blood cells. | the purpose of our study was to explore the possible scavenging property of black tea and catechins, the major flavonols of tea-leaf, against damage by oxidative stress. for this purpose, human red blood cell (rbc) was taken as the model and the oxidative damage was induced by a variety of inducers, e.g. phenylhydrazine (phx), cu(2+)-ascorbic acid, and xanthine/xanthine oxidase systems. lipid peroxidation of pure erythrocyte membrane and of whole red blood cell could be completely prevented by b ... | 1998 | 9535765 |
| consumption of tea and coffee and the risk of lung cancer in cigarette-smoking men: a case-control study in uruguay. | this study investigated the effect of drinking tea or coffee on the lung cancer risk of male cigarette smokers in a case-control in uruguay. four hundred and twenty-seven lung cancer cases were frequency matched on age and residence with 428 hospitalized controls suffering from conditions unrelated to tobacco smoking and diet. whereas coffee drinking had no effect on the lung cancer risk of the cigarette-smoking men in this study, black tea consumption decreased this risk. heavy drinkers of tea ... | 1998 | 9567246 |
| potent suppressing activity of the non-polyphenolic fraction of green tea (camellia sinensis) against genotoxin-induced umu c gene expression in salmonella typhimurium (ta 1535/psk 1002)--association with pheophytins a and b. | antigenotoxic and antimutagenic activities of green tea extract and tea-derived polyphenols have been studied using in vitro and in vivo experiments. however, antigenotoxic substances in the non-polyphenolic fraction of green tea have been poorly elucidated. in the present study, the effect of the non-polyphenolic fraction of green tea on genotoxin-induced umu c gene expression was analyzed using a tester bacteria, and potent antigenotoxic substances in the non-polyphenolic fraction were identif ... | 1997 | 9570394 |
| isolation and identification of acetyl-coa carboxylase inhibitors from green tea (camellia sinensis). | an aqueous methanol extract from green tea showed potent acetyl-coa carboxylase inhibitory activity. an active compound was isolated from the extract and identified as (-)-epigallocatechin gallate by instrumental analyses. the ic50 value of (-)-epigallocatechin gallate was 3.1 x 10(-4) m. among tea catechins and related compounds, nearly equal activity was found in (-)-epigallocatechin gallate and (-)-epicatechin gallate, whereas (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, gallic acid a ... | 1998 | 9571782 |
| inhibition of salivary amylase by black and green teas and their effects on the intraoral hydrolysis of starch. | tea decoctions prepared from a number of black and green teas inhibited amylase in human saliva. black teas gave higher levels of inhibition than green teas, and removal of tea tannins with gelatin led to the loss of inhibitory activity from all decoctions. streptococcal amylase was similarly inhibited by tea decoctions. fluoride was without effect on amylase. since salivary amylase hydrolyzes food starch to low molecular weight fermentable carbohydrates, experiments were carried out to determin ... | 1998 | 9577990 |
| tea antioxidants in cancer chemoprevention. | in recent years, the concept of cancer chemoprevention has matured greatly. significant reversal or suppression of premalignancy in several sites by chemopreventive agents appears achievable. this article summarizes experimental data on chemopreventive effects of tea polyphenols in different tumor bioassay systems. tea (camellia sinensis) is cultivated in about 30 countries, and is the most widely consumed beverage in the world. three main commercial tea varieties--green, black, and oolong--are ... | 1997 | 9591194 |
| effects of tea polyphenols and flavonoids on liver microsomal glucuronidation of estradiol and estrone. | administration of 0.5 or 1% lyophilized green tea (5 or 10 mg tea solids per ml, respectively) as the sole source of drinking fluid to female long-evans rats for 18 days stimulated liver microsomal glucuronidation of estrone, estradiol and 4-nitrophenol by 30-37%, 15-27% and 26-60%, respectively. oral administration of 0.5% lyophilized green tea to female cd-1 mice for 18 days stimulated liver microsomal glucuronidation of estrone, estradiol and 4-nitrophenol by 33-37%, 12-22% and 172-191%, resp ... | 1998 | 9605416 |
| tea and tea polyphenols inhibit cell hyperproliferation, lung tumorigenesis, and tumor progression. | both green and black tea have been shown to inhibit lung tumorigenesis in laboratory animal experiments. green tea inhibited n-nitrosodiethylamine-induced lung tumor incidence and multiplicity in female a/j mice when tea was given either during the carcinogen treatment period or during the post-carcinogen treatment period. in a separate tumorigenesis model, both decaffeinated black tea and decaffeinated green tea inhibited 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk)-induced lung tumor f ... | 1998 | 9659588 |
| antimutagenic activity of tea towards 2-hydroxyamino-3-methylimidazo[4,5-f]quinoline: effect of tea concentration and brew time on electrophile scavenging. | green tea and black tea inhibit colon carcinogenesis in rats exposed to the cooked meat-derived mutagen 2-amino-3-methylimidazo[4, 5-f]quinoline (iq). the present study compared the inhibitory activities of green tea and black tea towards a direct-acting mutagenic metabolite of iq, namely 2-hydroxyamino-3-methylimidazo[4, 5-f]quinoline (n-hydroxy-iq), under various brewing conditions. the following observations were made: (a) green tea (sencha midoriiro) and black tea (english breakfast tea) bre ... | 1998 | 9675318 |
| worldwide prevention of cancer and other chronic diseases based on knowledge of mechanisms. | international research, particularly as part of us/japan programs, has led to major advances in knowledge of causes of heart disease, stroke, many types of cancer and diabetes, showing that individual lifestyle is associated with these diseases. in japan, a major health problem is high blood pressure and stroke, and cancer of the stomach, from excessive use of salt and salted, pickled foods, and the relative low intake of protective fruits and vegetables. we identified a likely gastric carcinoge ... | 1998 | 9675332 |
| effect of black tea polyphenols on plasma lipids in cholesterol-fed rats. | the influence of black tea polyphenols on plasma lipid levels was investigated in rats fed a 15% lard and 1% cholesterol diet. the diet was supplemented with 1% black tea polyphenols extracted and condensed from black tea. rats fed the lard-cholesterol diet showed an increase in plasma cholesterol and liver lipids compared to rats fed a basal diet. the supplementation of black tea polyphenols in this lard-cholesterol diet decreased the lipid levels in the plasma and increased the fecal excretion ... | 1998 | 9675714 |
| black tea and mammary gland carcinogenesis by 7,12-dimethylbenz[a]anthracene in rats fed control or high fat diets. | epidemiological studies suggest that tea may reduce cancer risk, and in laboratory rodents, chemopreventive effects of tea or purified extracts of tea have been demonstrated in lung, gastrointestinal tract and skin. there is some evidence of chemoprevention by tea in the mammary gland, but the data are not conclusive. in order to evaluate more fully the possible influence of black tea on 7,12-dimethylbenz[a]anthracene (dmba)-induced mammary gland tumors in the female s-d (sprague-dawley) rat, th ... | 1998 | 9683188 |
| bulk acoustic wave bacterial growth sensor applied to analysis of antimicrobial properties of tea. | a bulk acoustic wave (baw) bacterial growth sensor has been proposed for study of inhibitory effects of tea by continuous monitoring of disturbances in proteus growth in the aqueous extracts of various teas, e.g. green tea, fuzhuan brick tea, oolong tea, kudin tea, and black tea. the kinetic parameters, e.g. asymptote (a), maximum specific growth rate (microm), lag time (lambda), and generation time (g), accurately estimated by using the growth response model, have been first used to characteriz ... | 1998 | 9694687 |
| potent suppressive activity of pheophytin a and b from the non-polyphenolic fraction of green tea (camellia sinensis) against tumor promotion in mouse skin. | chlorophyll-related compounds pheophytin a and b have been recently identified as antigenotoxic substances in the non-polyphenolic fraction of green tea (camellia sinensis), which suppressed umu c gene expression in tester bacteria induced by various genotoxins (okai and higashi-okai, cancer lett. 118 (1997) 117-123). in the present study, the authors analyzed in vivo and in vitro effects of pheophytin a and b from the non-polyphenolic fraction of green tea on tumor promotion in mouse skin as fo ... | 1998 | 9719465 |
| contribution of caffeine and flavanols in the induction of hepatic phase ii activities by green tea. | aqueous extracts of green tea, at concentrations of 2.5. 5.0 and 7.5%, were administered to rats as the sole drinking fluid for 4 weeks. hepatic glutathione s-transferase (gst) activity, determined using 1-chloro-2,4-dinitrobenzene (cdnb) and 3,4-dichloronitrobenzene (dcnb) as substrates, and udp-glucuronosyl transferase activity, determined using 2-aminophenol as substrate, were induced but the effect was not always dose dependent. at the two highest doses, hepatic catalase activity was inhibit ... | 1998 | 9734711 |
| the effect of a component of tea (camellia sinensis) on methicillin resistance, pbp2' synthesis, and beta-lactamase production in staphylococcus aureus. | extracts of tea (camellia sinensis) can reverse methicillin resistance in methicillin-resistant staphylococcus aureus (mrsa) and also, to some extent, penicillin resistance in beta-lactamase-producing s. aureus. these phenomena are explained by prevention of pbp2' synthesis and inhibition of secretion of beta-lactamase, respectively. synergy between beta-lactams and tea extracts were demonstrated by disc diffusion, chequerboard titration and growth curves. partition chromatography of an extract ... | 1998 | 9738838 |
| dietary antioxidants inhibit development of fatty streak lesions in the ldl receptor-deficient mouse. | oxidized low density lipoprotein (ldl) promotes atherogenesis. although pharmacological antioxidants such as probucol inhibit both ldl oxidation and atherosclerosis in hyperlipidemic animals, the effects of natural antioxidants such as vitamin e are inconclusive. to further determine the effects of supplemental dietary antioxidants in vivo, we evaluated whether combined dietary antioxidants (0.1% vitamin e, 0.5% beta-carotene, and 0.05% vitamin c) inhibit ldl oxidation and fatty streak lesion de ... | 1998 | 9743241 |
| inhibition of lung carcinogenesis by black tea in fischer rats treated with a tobacco-specific carcinogen: caffeine as an important constituent. | here, we examined the effect of black tea and caffeine on lung tumorigenesis in f344 rats induced by the nicotine-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk) in a 2-year bioassay. nnk was administered s.c. at a dose of 1.5 mg/kg body weight three times weekly for 20 weeks. animals were given either black tea as drinking water at concentrations of 2%, 1%, or 0.5%, or caffeine in drinking water at concentrations identical to those in 2% and 0.5% tea infusions for 22 wee ... | 1998 | 9751618 |
| potent suppressive activity of chlorophyll a and b from green tea (camellia sinensis) against tumor promotion in mouse skin. | potent antigenotoxic and anti-tumor promoting activities of chlorophyll a from green tea (camellia sinensis) have been shown using in vitro cell culture experiments (okai y. et al. (1996) mutation res., 370, 11-17). in the present study, the authors analyzed in vivo effects of chlorophyll a and b from green tea on tumor promotion in mouse skin in the following ways. 1. when chlorophyll a and b from green tea were applied before each treatment by a tumor promoter, 12-o-tetradecanoyl-phorbol-13-ac ... | 1998 | 9760704 |
| an in vitro study of theaflavins extracted from black tea to neutralize bovine rotavirus and bovine coronavirus infections. | crude theaflavin was extracted from black tea and then fractionated by hplc into five components (initial peaks (ip), tf1, tf2a, tf2b, and tf3). the crude extract and the various fractions of theaflavin were collected and tested, individually and in combination, for antirotaviral activity. the mean effective concentration (ec50) was calculated and compared. activity varied from the most active being the uncharacterized theaflavin-like initial peaks (ip) with an ec50 of 0.125 microgram/ml to the ... | 1998 | 9850995 |
| black tea theaflavins induce programmed cell death in cultured human stomach cancer cells. | the exposure of human stomach cancer kato iii cells to black tea theaflavin extract, free theaflavin, and theaflavin digallate that are main components of the extract, led to both growth inhibition and the induction of programmed cell death (apoptosis). morphological changes showing apoptotic bodies were observed in the cells treated with black tea theaflavin extract, theaflavin and theaflavin digallate. the fragmentations by these theaflavin compounds of dna to oligonucleosomal-sized fragments ... | 1998 | 9852288 |
| protective action of plant polyphenols on radiation-induced chromatid breaks in cultured human cells. | the present study was performed to determine whether plant polyphenols can protect human cells against radiation-induced dna damage manifested as chromatid breaks. since each chromatid contains a single continuous molecule of double stranded dna, chromatid breaks represent unrepaired dna strand breaks. the addition of green or black tea extracts, their polyphenols or curcumin to cultures of human skin fibroblasts or pha-stimulated blood lymphocytes significantly reduced the frequencies of radiat ... | 1998 | 9858893 |
| contribution of theafulvins to the antimutagenicity of black tea: their mechanism of action. | theafulvins were isolated from black tea aqueous infusions and their antimutagenic activity was evaluated against a number of food carcinogens. theafulvins gave rise to a concentration-dependent inhibition of the mutagenicity of 2-amino-3-methylimidazo-[4,5-f]quinoline, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene, nitrosopyrrolidine and nitrosopiperidine, but, in contrast, the mutagenicity of aflatoxin b1 was enhanced. the mutagenicity exhibite ... | 1998 | 9862196 |
| role of glutathione in the antiulcer effect of hot water extract of black tea (camellia sinensis). | the role of a hot water extract of black tea (camellia sinensis (l). o. kuntze theaceae) in the gastric cytoprotective mechanisms was studied using gastric mucosal lesions produced by various ulcerogens in rats as an experimental model. prior oral administration of black tea extract (bte) at 20 ml/kg, i.g. once a day for 7 days significantly reduced the incidence of gastric erosions and severity induced by ethanol, diethyldithiocarbamate (ddc) and diethylmaleate (dem). this treatment also favora ... | 1998 | 9869262 |
| antibacterial activity of camellia sinensis extracts against dental caries. | different bacteria were separated from saliva and teeth of cariogenic patients and identified by a variety of morphological and biochemical tests. extracts of green tea strongly inhibited escherichia coli, streptococcus salivarius and streptococcus mutans. the antibacterial effect of green and black tea extracts were compared with those of amoxicillin, cephradine and eugenol. | 1998 | 9875456 |
| effect of green tea and black tea on the metabolisms of mineral elements in old rats. | a 2-mo experiment with the white sprague-dawley (sd) rats was conducted to investigate the effect of the water extracts of black tea (btwe) and green tea (gtwe) and the black tea leaves (btf) and the green tea leaves (gtf) on the metabolism of mineral elements. one hundred eight 12-mo-old white sd rats were randomly divided into 13 groups; 6 of these drank the btwe or gtwe in which the water extracts concentrations of black tea or green tea were, respectively, 0.6%, 1.2%, and 2.4%, and 6 of thes ... | 1998 | 9877538 |
| 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 |
| effects of tea infusions of various varieties or different manufacturing types on inhibition of mouse mast cell activation. | we investigated effects of various tea infusions on mast cell activation using mouse mast cells. among various tea extracts, infusions from cultivar 'benihomare' and taiwan lineage strongly inhibited histamine release after fc epsilon ri cross-linking. among three types of tea (from cultivar 'benihomare'), extract from oolong tea or black tea inhibited histamine release more strongly than green tea extract. furthermore, 'benihomare' oolong tea extract suppressed tyrosine phosphorylation of cellu ... | 1998 | 9972253 |
| chemopreventive effects of black tea polyphenols in mouse skin model of carcinogenesis. | in the present investigations, the antitumorigenic effect of black tea polyphenols (btp) in two-stage mouse skin model of carcinogenesis was studied. the animals were initiated with a single "subcarcinogenic" topical dose (52 micrograms/200 microliters acetone) of 7, 12-dimethylbenzanthracene (dmba). to evaluate the anti-tumour initiating activity, btp was topically applied twice a week for three weeks prior to dmba application, followed by topical treatment with 12-o-tetradecanoyl phorbol-13-ac ... | 1998 | 10095927 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| fluoride in tea--its dental significance: a review. | it has long been accepted that fluoride accumulates in the leaves of the tea plant. camellia sinensis. in addition it is known that some of this fluoride is released into the infusion which is drunk as tea. the exact concentration of fluoride in a cup of tea and the effects of this fluoride have been the subject of many international studies. this review summarizes the main points of such studies which have been carried out in an attempt to establish the dental significance of fluoride in tea. t ... | 1998 | 10530119 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |