mutagens in coffee and prepared in the usual way for drinking contains a substance(s) that is mutagenic to salmonella typhimurium ta100 without mammalian microsomal enzymes. one cup of coffee (200 ml) contains mutagen(s) inducing 1.4-4.6 x 10(5) revertants under standard conditions. instant coffee too is mutagenic to ta100 and one cup of instant coffee prepared from 1 g of coffee powder and 200 ml of water induced 5.6-5.8 x 10(4) revertants of ta100. caffeine-free instant coffee also has similar mutagenicity. a ...1979390384
[protective activity of tea and catechins against bordetella pertussis].we examined the bactericidal activity of tea and catechins against bordetella pertussis. green tea, black tea and coffee showed marked bactericidal activity at their concentrations in beverages, while pu-erh tea killed the bacteria in a moderate way. (-) epigallocatechin gallate (egcg) and theaflavin digallate (tf3) showed also marked bactericidal activity. green tea and black tea also effectively blocked the adhesion of b. pertussis to hela and cho cells, whereas ecgg and tf3 could not. egcg an ...19921402092
[antimicrobial and microbicidal activities of tea and catechins against mycoplasma].we examined tea extracts, (-) epigallocatechin gallate (egcg) and theaflavin digallate (tf3) for their antimicrobial and microbicidal activities against mycoplasma. green tea and black tea showed antimicrobial activities against m. pneumoniae. at a concentration of 0.2% green tea and black tea showed microbicidal activities against m. pneumoniae and m. orale but not against m. salivarium. extracts of pu-erh tea showed a slight microbicidal activity against m. pneumoniae and m. orale. egcg purifi ...19921402093
antioxidative effect of polyphenol extract prepared from various chinese teas.methods. twelve different types of chinese teas, including green, semifermented, and black tea, were studied for their antioxidant activities and active components. compositions of (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, (-)-epigallocatechin gallate, and gallic acid were identified by fast atom bombardment-mass spectrometry and high-performance liquid chromatography-mass spectrometry and quantified by high-performance liquid chromatography. antioxidant activities in lard ...19921409493
differential inhibitory effects of some catechin derivatives on the activities of human immunodeficiency virus reverse transcriptase and cellular deoxyribonucleic and ribonucleic acid polymerases.the two components of camellia sinensis (tea plant) [i.e., (-)-epicatechin gallate and (-)-epigallocatechin gallate] were found to differentially inhibit the activities of reverse transcriptase and cellular dna and rna polymerases. under the assay conditions optimized for each enzyme species, the strongest inhibition by these compounds was observed with reverse transcriptase. the concentrations of (-)-epicatechin gallate and (-)-epigallocatechin gallate required for 50% inhibition of the activit ...19901693287
the protective activity of tea against infection by vibrio cholerae o1.extracts of black tea exhibited bactericidal activity against vibrio cholerae o1. the tea extract inhibited the haemolysin activity of v. cholerae o1, el tor and the morphological changes of chinese hamster ovary cells induced by cholera toxin. tea extract also reduced fluid accumulation induced by cholera toxin in sealed adult mice and by v. cholerae o1 in ligated intestinal loops of rabbits. these findings suggest that tea has protective activity against v. cholerae o1.19912019547
[anti-caries effects of polyphenol compound from camellia sinensis].polyphenol compound (designated sunphenon) from leaf of camellia sinensis have been partially purified by extraction of the boiling water with ethyl acetate. the effect of sunphenon on cariogenic streptococcus mutans groups (serotype c and g) was studied in both in vitro and in vivo. the summary of results were described as follows; 1) addition of sunphenon to s. mutans jc-2 (c) caused a decrease in cell viability. the activity of sunphenon showed that multiple application are required for killi ...19902135607
effect of tea polyphenols on glucan synthesis by glucosyltransferase from streptococcus the course of our studies on the development of anti-plaque agents for prevention of dental caries, we investigated effects of some of tea preparations and their individual components on the glucan synthesis catalyzed by glucosyltransferase (gtf) from streptococcus mutans. extracts of green tea and black tea, and polyphenol mixtures showed appreciable inhibition in the synthesis of insoluble glucan. among the components isolated from tea infusions, theaflavin and its mono- and digallates had ...19902140716
[effect of triterpene glycosides on plasma membrane permeability for uv-absorbing substances in saccharomyces carlsbergensis yeast cells].the effect of triterpene glycosides of cauloside c from caulophyllum robustum m, stichoposide a from stichopus japonicus s. and theasaponine from thea sinensis z. on permeability of plasmic membranes of saccharomyces carlsbergensis for uv-absorbing substances was studied. it was found that incorporation of 14c-uridine from the endocellular pool into the yeast acid-insoluble fraction decreased under the effect of the triterpene glycosides as a result of the precursor leakage from the cell into th ...197934359
folklore therapeutic indigenous plants in periodontal disorders in india (review, experimental and clinical approach).though a number of plants and their parts are used for dental ailments among population in rural and urban areas of developing countries, in india however, the most common house-hold, road-side plants are mango (mangifera indica), neem (azadirachta indica; melia azadirachta), ocimum (ocimum basilicum), tea-dust (camellia sinensis) and uncommonly murayya, i.e., currey leaf (murayya koenigi) [chopra et al. 1958, kirtikar and basu 1935, nadakarni 1954, satyavati 1984]. the leaves of these plants ar ...19883042642
protein conversion efficiencies of four test diets based on milk, two milk and tea treatments, and casein.milk consumption in 80 households in western kenya averaged .25 to 1.00 l per family per day. most of this milk was processed into a milk and tea beverage. polyphenols, the major determinants of tea flavor and character, form soluble complexes with casein when black tea infusions are mixed with milk. test diets were prepared from the following treatments: a) casein reference diet; b) milk, no tea leaves; c) milk added after heat treatment; and d) traditional kenyan-style tea (i.e., milk and tea ...19863722539
chromosome aberrations induced by aflatoxin b1 in rat bone marrow cells in vivo and their suppression by green tea.aflatoxin b1 (afb1)-induced chromosome aberrations (ca) in rat bone marrow cells consisted mainly of gaps and breaks. cells with exchanges and multiple ca were observed infrequently. the incidence of aberrant cells and the number of aberrations per cell were at their maximum levels 18 h after the afb1 injection. they were dependent on the administered dose of afb1. rats given the hot water extract from green tea (gte) 24 h before they were injected with afb1 displayed considerably suppressed afb ...19892922009
crude tea extracts decrease the mutagenic activity of n-methyl-n'-nitro-n-nitrosoguanidine in vitro and in intragastric tract of rats.the effects of tea extracts and their ingredients, catechins and l-ascorbic acid (asa), on the mutagenicity of n-methyl-n'-nitro-n-nitrosoguanidine (mnng) were examined in vitro and in the stomachs of rats using e. coli wp2 and s. typhimurium ta100. the extracts of green tea and black tea leaves decreased the mutagenic activity of mnng to e. coli wp2 in vitro in a desmutagenic manner. catechins such as (-)-epigallocatechin from green tea leaves and the low-molecular-weight tannin fraction isolat ...19892642597
differential inhibition of hiv-reverse transcriptase and various dna and rna polymerases by some catechin derivatives.the two components of camellia sinensis (green tea) (i.e., (-)-epigallocatechin gallate and (-)-epicatechin gallate were found to differentially inhibit the activities of reverse transcriptase and cellular dna and rna polymerases. the strongest inhibition by these compounds was observed with reverse transcriptase. dna polymerases alpha and beta were also strongly inhibited. the mode of the inhibition of reverse transcriptase and other dna polymerases was competitive with respect to the template. ...19892481838
diphenylamine, an antihyperglycemic agent from onion and tea.diphenylamine has been isolated as one of the active antihyperglycemic agents of onion. it was identified by ir, uv, cmr, pmr, and mass spectra. it attained the highest percentage in mature onion bulbs; other onion organs contained diphenylamine in lower percentages. green and black teas were found to contain relatively high percentages of diphenylamine, being higher in the former. cooking was found to decrease the diphenylamine content.19846512531
inhibition of platelet activation and endothelial cell injury by flavan-3-ol and saikosaponin compounds.the effects of flavan-3-ol and saikosaponin compounds on platelet aggregation, platelet thromboxane biosynthesis and h2o2-induced endothelial cell injury were studied. seven flavan-3-ol compounds isolated from camellia sinensis l. var sinensis o. kuntze (theaceae) and three saikosaponin compounds isolated from bupleurum falcatum l. (umbelliferae) were used. among the 10 compounds tested, only epigallocatechin and saikosaponin a significantly inhibited human platelet aggregation induced by adp, a ...19911946562
mutagenicity and carcinogenicity of tea, camellia sinensis.aqueous, caffeine free and tannin fractions of commercial tea and tannic acid were tested for mutagenicity in ames test. tea fractions of tannic acid were non mutagenic in strains ta 100, ta 98, ta 1535 and ta 1538 of salmonella typhimurium with or without metabolic activation (rat-s9 mix) at different doses tested. in strain ta 98 the above tea fractions and tannic acid inhibited the s9 mix mediated mutagenicity of tobacco in a dose dependent manner. the different tea fractions at 60 degrees c, ...19911916936
tea tannin components modify the induction of sister-chromatid exchanges and chromosome aberrations in mutagen-treated cultured mammalian cells and mice.the modifying effects of tannin components extracted from green tea and black tea on mutagen-induced sces and chromosome aberrations were studied. these tannin components did not affect spontaneous sces and chromosome aberrations in cultured chinese hamster cells. the frequency of sces and chromosome aberrations induced by mitomycin c (mmc) or uv was enhanced by the posttreatment with tea tannin components. when cells were post-treated with tea tannin components in the presence of metabolic enzy ...19911899132
niacin, thiamin, iron and protein status of humans as affected by the consumption of tea (camellia sinensis) infusions.the objective of the project was to determine the effects of tea (camellia sinensis) leaf beverage consumption on the apparent utilization of niacin, thiamin, and protein in human subjects. during two randomly arranged experimental periods of 14 days each, 10 adult female human subjects were fed a constant (same foods each day), measured, laboratory-controlled diet. tea was fed during one period while no tea was allowed during the other period. a dehydrated black tea infusion product (instant te ...19911796091
dietary nicotine: a source of urinary cotinine.foods, principally from plants in the family solanaceae, and a number of teas were examined for the presence of nicotine. dietary nicotine would give rise to cotinine in urine and compromise estimates of exposure to tobacco smoke that depend on urinary cotinine. all foods were homogenized, extracted and analysed for nicotine and cotinine by gas chromatography with nitrogen-sensitive detection (gc) and/or gc/ms (mass spectrometry). weak acid and aqueous extracts of the teas were analysed in a sim ...19911765327
inhibition of rotavirus and enterovirus infections by tea extracts.epigallocatechin gallate from green tea and theaflavin digallate from black tea inhibited infections of cultured rhesus monkey kidney ma 104 cells with rotaviruses and enteroviruses. their antiviral effects were maximally induced when directly added to virus, and their pre- and post-treatment of the cells produced much weak antiviral activity. antiviral activity of the extracts therefore seems to be attributable to interference with virus adsorption.19911668240
the inhibitory effect of plant extracts on the collagenolytic activity and cytotoxicity of human gingival fibroblasts by porphyromonas gingivalis crude is well known that plant extracts inhibit some enzymatic activities. the present study examined the inhibitory effects of natural plant extracts against the collagenolytic activity of porphyromonas gingivalis. the enzyme was isolated from a culture supernatant of p. gingivalis 381. the aqueous and 50% ethanolic extracts of ginkgo biloba, mosla chinensis, salvia officinalis, cinnamomum cassia, and a catechin extract of camellia sinensis exhibited strong inhibitory effects on collagenolytic act ...19911668071
anticaries effects of polyphenolic compounds from japanese green tea.the dental caries inhibiting effect of the extract from japanese green tea, one of the most popular drinks in japan, was studied both in vitro and in vivo. the crude tea polyphenolic compounds (designated sunphenon) from the leaf of camellia sinensis were found to effectively inhibit the attachment of streptococcus mutans strain jc-2 (serotype c) to saliva-coated hydroxyapatide discs. sunphenon was also inhibitory to water-insoluble glucan formation from sucrose by crude glucosyltransferase of s ...19911667297
the effects of chinese tea on the occurrence of esophageal tumors induced by n-nitrosomethylbenzylamine in rats.based on previous studies on the blocking effect of chinese tea in the formation of n-nitroso compounds in rats and humans, experiments were carried out to study the effects of chinese tea on the occurrence of esophageal tumors induced by n-nitrosomethylbenzylamine (nmbza) in rats.19921615000
anti-ulcer effect of the hot water extract of black tea (camellia sinensis).the effect of the hot water extract of black tea (camellia sinensis (l.) o. kuntze, theaceae) on ulceration induced by various ulcerogens and by cold restraint stress (crs) was investigated in albino rats. while prior administration of tea extract for 7 days significantly reduced the incidence of ulcer, ulcer number and ulcer index produced by aspirin, indomethacin, ethanol, reserpine and crs, it failed to inhibit the ulcers induced by serotonin and histamine. tea extract also favourably altered ...19957564415
anti-hyperglycemic effect of black tea (camellia sinensis) in rat.investigations were carried out to evaluate the effect of the hot water extract of black tea (camellia sinensis (l.) o. kuntze (theaceae) on streptozotocin (stz)-induced diabetes in rats. the extract significantly reduced the blood glucose level and was found to possess both preventive and curative effects on experimentally produced diabetes in rats. the study reveals that, like green tea, black tea also possesses antidiabetic activity.19957623488
[microbial contamination of twenty drugs of plant origin].twenty drugs of plant origin were analysed in order to determine the microbial contamination level. a light homogenizing method was used to avoid an increase in the antimicrobial capacity of certain drugs, which would falsify the analytical results. the total viable aerobic count (tvc) varied from 10(1) to 10(7) cfu/g and in 11 samples out of 21 was equal to or higher than 10(5) cfu/g. the number of fungi varied from one drug to another, but was generally lower than the aerobic tvc to the power ...19921438458
(-)-epigallocatechin-3-gallate in camellia sinensis leaves from himalayan region of sikkim: inhibitory effects against biochemical events and tumor initiation in sencar mouse skin.recently, we and others showed that the components of green tea may be useful cancer chemopreventive agents. it has been suggested that (-)-epigallocatechin-3-gallate (egcg), the major constituent in green tea, may possess antitumor-promoting and/or anticarcinogenic effects in rodent tumor bioassay systems. during the chemical analysis of various green tea products, we found a traditionally preserved preparation of green tea used by tribes in the himalayan region of sikkim, india that was rich i ...19921408948
antibacterial activity of tea (camellia sinensis) and coffee (coffee arabica) with special reference to salmonella typhimurium.extracts of black tea, japanese green tea, china tea or coffee inhibited the growth of various bacteria causing diarrhoeal diseases. tea or coffee also showed bactericidal activity against vibrio cholerae, salmonella typhimurium and salmonella typhi.19947868837
[effect of triterpene glycosides on rna biosynthesis in a yeast cell culture of saccharomyces carlsbergensis].the effect of triterpen glycosides of cauloside c from caulophyllum robustum, theasaponine from thea sinensis ahd stichoposide a from stichopus japonicus on multiplication and biosynthesis of rna in the cells of a 7-hour culture of saccharomyces carlsbergensis was studied. it was shown that cauloside c, theasaponine and stichoposide a in concentrations of 7.5 gamma/ml inhibited multiplication of the yeast cells by 65, 10 and 90 per cent respectively. the summation rna of the yeast cells is divid ...1977911157
effect of the hot-water extract of black tea (camellia sinensis) on the rat diaphragm. 19947997479
[effect of triterpene glycosides on the plasma membrane permeability for amino acids in saccharomyces carlsbergensis yeast cells].the effect of triterpen glycosides, such as cauloside c from caulophyllum robustum, stichoposide a from stichopus japonicus s and the asaponine from thea sinensis l on permeability of the plasmic membranes for amino acids was studied. it was shown that the glycosides induced higher levels of liberation of the amino acids with positively or negatively charged molecules from the cells of saccharomyces carlsbergensis as compared to the control. the transport of the non-polar amino acids was least a ...1978623450
[fluorine content in the urine and in the serum of hydrofluoric acid workers as an index of health administration (author's transl)].the behavior of fluoride ion level in the urine and in the serum was measured as an index for health care of workers exposed to hydrofluoric acid, the effect of fluorine-containing foodstuff intake by the workers being considered at the same time. for this study, 250 hydrofluoric acid workers and as a control group 1,600 non-hydrofluoric-acid workers were examined. all workers, ranging in age from 15 to 59 years old, came from the same electronics factory. fluorides in the biological fluids were ...1979537219
carcinogenicity of camellia sinensis (tea) and some tannin-containing folk medicinal herbs administered subcutaneously in an attempt to correlate the high incidence of esophageal carcinoma in natives of certain places with their habit of using herbaceous folk medicines, we performed bioassays of several plant extracts and the fractions prepared from them. fourteen extracts and fractions from 6 plants were injected sc into nih black rats. the tannin fractions from quercus falcata pagodaefolia, diospyros virginiana, and camellia sinensis were very active and produced tumors at the injection site in 66% or more of ...1976187761
iron, copper and zinc metabolism of rats fed various levels and types of tea.the effects of tea and components in tea on mineral metabolism were investigated in a series of studies. in studies a and b weanling rats were fed diets containing various levels (0, 0.35, 1.17 or 3.50%) of a commercially prepared instant tea and diets containing 0 or 1.17% catechin. in study c anemic rats were fed diets containing 0 or 2.31% desiccated green or black tea infusions for 23 d. in study d rats were fed a diet containing 2.31% desiccated black tea infusions for 16 d, were fed the te ...19883335939
[inhibition of the infectivity of influenza virus by black tea extract].we determined whether black tea extract inhibits the infectivity of influenza virus to mice. when mice were inoculated intranasally with 10(5.3) pfu influenza viruses (10(1.3) ld50), their body weight decreased and all died within 10 days. whereas, when mice were inoculated i.n. with the mixture of influenza viruses and 2% (w/w) black tea extract, 5 min after mixing, all mice showed normal body-weight increase and survived. neutralizing antibody to influenza virus was not detected in nine of 10 ...19948089547
mutagens in coffee and other beverages.a cup of coffee contains mutagens which produce about 5 x 10(4)-10(5) revertants of salmonella typhimurium ta 100 without s9 mix. one of the mutagens was identified to be methylglyoxal. methylglyoxal was present in various beverages such as black tea, whisky, and brandy. methylglyoxal itself induced tumors in rats when administered by subcutaneous injection. however, the mutagenic properties of coffee were different from those of methylglyoxal. the mutagenicity of coffee was suppressed by catala ...19863757962
the influence of dietary tea, coffee and cocoa on protein and energy utilization of soya-bean meal and barley in rats.two series of balance experiments were performed with growing rats to test the effect of black tea, green tea, coffee and cocoa on protein and energy utilization. in expt 1 soya-bean meal was fed as a basal diet and supplemented with freeze-dried materials from 11 black tea, green tea or coffee/500 g dry matter. cocoa powder, corresponding to 11 of the beverage, was also added to the basal diet. in expt 2 the procedure was repeated with a barley-based diet. in both experiments both tea varieties ...19836684477
three-month oral repeated administration toxicity study of seed saponins of thea sinensis l. (ryokucha saponin) in rats.ryokucha saponin (rsp), which is one of the ingredients of green tea, was administered orally to rats for 3 months at dose levels of 50, 150 and 500 mg/kg/day to assess any toxic effects. as positive control, 1200 mg/kg/day of quillaia saponin (qsp), which contains saponins equivalent in amount to those in 500 mg rsp/kg/day, was administered. the no-effect level of rsp was 50 mg/kg/day and the lowest-observed-effect level of rsp was 150 mg/kg/day for both sexes, so that the true no-effect level ...19948206442
mutagenicity of hydrolysates of tea infusions.hydrolysates of infusions of green tea and black tea were mutagenic by the ames test. the tea infusions were prepared by a regular method and were hydrolysed with 1 m hcl, hesperidinase, naringinase and human intestinal bacteria. the hydrolysates were successively extracted with chloroform, diethyl ether and ethyl acetate. the mutagenicities of the extracts were assayed by the ames test, and the mutagens were analysed by gc-ms. the ether extracts of the hydrolysates of infusions of both green te ...19817019686
mutagenicity of various japanese foodstuffs treated with nitrite.mutagenic activities of various japanese foodstuffs treated with nitrite at ph 4.2 for 10 min (37 degrees c) were tested using salmonella typhimurium ta 100, ta 1535 and also a streptomycin(sm)-dependent strain of salmonella typhimurium ta 100. among 46 common food samples tested, smoked ham, red wines, black teas, soybean pastes and instant coffee powder gave greatly increased numbers of his+ revertants or sm-independent colonies when treated with nitrite. vegetables, soybean-seasonings and a v ...19827141563
[effect of triterpene glycosides and polyene antibiotics on cell membrane permeability for k+ ions and uv-absorbing substances].the effect of triterpene glycosides (cauloside c from caulophyllum robustum, theasaponine from thea sinensis, cucumarioside g from cucumaria fraudatrix stichoposide a from stichopus japonicus s., holothurines a and b from holothuria mexicana, holothurine c from bohadschia sp.) on the membrane permeability for k+ ions and uv-absorbing substances was compared with that of polyene antibiotics, viz., amphotericine b and nystatine. as a biological model fertilized eggs of sea urchin strongylocentrotu ...19817198783
site-specific dna cleavage by mammalian dna topoisomerase ii induced by novel flavone and catechin derivatives.four naturally occurring flavones (baicalein, quercetin, quercetagetin and myricetin) and two novel catechins [(-)-epicatechin gallate and (-)-epigallocatechin gallate, from the tea plant camellia sinensis], which are known inhibitors of reverse transcriptase, were shown to induce mammalian topoisomerase ii-dependent dna-cleavage in vitro. the flavones differed from the catechins in causing unwinding of duplex dna, but both classes of compound induced enzymic dna breakage at the same sites on dn ...19921313232
effect of consumption of green and black tea on the level of various enzymes in rats.drinking of both green and black tea as the only liquid ingested resulted in significant decreases in the activity of transketolase in whole blood of rats both before and after the in vitro addition of thiamin diphosphate. liver transketolase activity was decreased only by green tea. mucosal transketolase activity was not affected by either type of tea. the activity of lactate dehydrogenase (ldh) was not affected by either type of tea, while whole blood ldh was decreased by both green and black ...19892912766
inhibition of iron absorption prolongs the life span of drosophila.the life span of drosophila melanogaster (oregon r) males was found to be proportional to the logarithm of the iron content of the diet. life span was also shown to be proportional to the rate of iron accumulation for drosophila, mice and man. the total body iron content was found to correlate with the total calcium content of adult drosophila. iron content during the developmental stages, however, remained relatively constant and did not change with changes in the calcium concentrations. dietar ...19938326745
folacin content of folacin and free folacin activities of 22 commercial tea samples, involving 5 types and 14 brands, were determined by a microbiological assay, using lactobacillus casei (atcc 7469). substantially higher amounts of folacin were found in tea leaves than had been reported previously, due to an improved assay method with added ascorbic acid to protect the labile folate forms. tea brews made from green and black teas contained approximately three to four times more folacin than the brews made f ...19836853937
inhibition of n-nitrosomethylbenzylamine-induced esophageal tumorigenesis in rats by green and black this study, we investigated the effects of green tea and black tea, when given either during or after carcinogen treatment, on esophageal tumorigenesis in male sprague-dawley rats. rats were treated with n-nitrosomethylbenzylamine (nmbza) (2.5 mg/kg, s.c., twice weekly) for 5 weeks; 39 weeks after the initial dose of nmbza, 65% of the rats had esophageal tumors with an average of 1.4 +/- 0.3 tumors per rat. in the groups of rats receiving 0.6% of decaffeinated green tea (dgt) or decaffeinated ...19957554067
[on the pharmacology of tea-seed-saponins of a saponin mixture from thea sinensis l]. 19685755916
prophylactic effect of tea on pathogenic microorganism infections to humans and animals. (ii). protozoacidal effect on toxoplasma gondii in vitro and mice.the trophozoites of toxoplasma gondii strain (rh) obtained from the peritoneal exudate of infected mice were treated with tea in various concentrations of 0.5, 1, 3 and 5% for 0.5, 1 and 3 hours, respectively. after treatment, they were intraperitoneally inoculated into the mice to observe the protozoacidal effect of tea. the results obtained are as follows: 1) oolong tea and green tea had stronger protozoacidal effect than black tea. 2) the lowest and effective concentration of tea tested to ki ...19827169306
[effect of triterpene glycosides on the biosynthesis of sterols and fatty acids by the yeast saccharomyces carlsbergensis].the effect of cauloside c from caulophyllum robustum m., theasaponine from thea sinensis l. and stichoposide a from stichopus japonicus s. on the biosynthesis of sterols and fatty acids by the yeast saccharomyces carlsbergensis was studied. in in vivo and in vitro experiments cauloside c and theasaponine inhibited ergosterol biosynthesis at the stage of squalene-to-lanosterol transformation. in in vivo experiments stichoposide a inhibited squalene biosynthesis. the triterpene glycosides tested s ...1978724665
inhibition of n-nitrosodiethylamine- and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced tumorigenesis in a/j mice by green tea and black tea.the effect of p.o. administration of tea on nitrosamine-induced carcinogenesis was investigated. female a/j mice were given n-nitrosodiethylamine (ndea) (10 mg/kg) p.o. once a week for 8 weeks and were killed 16 weeks after the last dose. more than 90% of the mice had forestomach and lung tumors. the animals had an average of 8.3 forestomach and 2.5 lung tumors/mouse. with 0.63 or 1.25% green tea infusion (12.5 g green tea leaves brewed with 1 liter of boiling water) as the sole source of drinki ...19921551122
effect of feeding coffee and its lipids on regenerating and intact liver.liver regeneration was stimulated in partially hepatectomized rats fed diets supplemental with up to 7.0% by weight of ground green and roasted brazilian or hawaiian (kona) coffee in a basal powdered ration but was little influenced by decaffeinated or african robusta coffee diets over a period of 10 days. the causative agent occurred in the total lipids from the active ground coffee batches and could be concentrated in the unsaponifiable portion as was also noted with the product from robusta c ...19807403660
[effect of natural complexes of biologically active substances on liver regeneration in alcohol poisoning].hepatoprotective effect of natural substances obtained from extracts of grape combs, leaves of green and black tea were studied in liver tissue of ethanol-consuming rats by means of evaluation of the neutral lipid fractions and phospholipids as well as by measurement of glucose and nicotinamide coenzymes nad+ and nadp in blood. in all the animal groups treated with these vegetable extracts content of total phospholipids, decreased after the ethanol treatment, was increased, while fraction compos ...19957793089
the yeast spectrum of the 'tea fungus kombucha'.the tea fungus 'kombucha' is a symbiosis of acetobacter, including acetobacter xylinum as a characteristic species, and various yeasts. a characteristic yeast species or genus has not yet been identified. kombucha is mainly cultivated in sugared black tea to produce a slightly acidulous effervescent beverage that is said to have several curative effects. in addition to sugar, the beverage contains small amounts of alcohol and various acids, including acetic acid, gluconic acid and lactic acid, a ...19958559192
effects of green and black tea on hepatic xenobiotic metabolizing systems in the male f344 rat.1. the induction of phase i and ii enzymes in the liver of the male f344 rat drinking 2% (w/v) solutions of green or black tea for 6 weeks was investigated. also studied were glutathione (gsh) and cyst(e)ine in blood, liver and kidney, as well as serum cholesterol, hdl cholesterol, triglycerides, and total and free testosterone. 2. the total carbon monoxide-discernible liver p450, b5 and nadph-cytochrome c(p450) reductase activities were similar in all groups. 3. there were significant increases ...19948017087
effects of seed saponins of thea sinensis l. (ryokucha saponin) on alcohol absorption and metabolism.we evaluated the effects of the seed saponins of thea sinensis l. on alcohol absorption and metabolism in rats and mice. an ethanolic extract from the seeds of t. sinensis was orally administered to the rats 1 hr before or 0.5 hr after administration of ethanol (2 g/kg), and the blood ethanol assayed 0.5, 1, 2, 3, and 4 hr after ethanol administration. the ethanol level decreased after both pre- and post-administration of the extract. the extract was further purified to obtain a saponin fraction ...19938147976
inhibition of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) mutagenicity by black and green tea extracts and of lyophilized preparations of standard black and green tea extracts were made and tested over a range of six concentrations as inhibitors of the mutagenicity caused by the fool mutagen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) in the salmonella typhimurium ta98 assay containing s9 fraction from rats induced with alpha-naphthoflavone and phenobarbital. extracts of both black and green tea were equally good inhibitors of mutagenicity. purified polyphenols were prepared from ...19968618547
reduction of oxalate content of foods by the oxalate degrading bacterium, eubacterium lentum wyh-1.urinary oxalate may contribute far more than urinary calcium to the pathogenesis of urinary calculi. urinary oxalate may be reduced by restricting the intake of foods high in oxalate. the oxalate content foods might be reduced by oxalate-degrading bacteria. the purpose of this experiment was to reduce the oxalate content of foods with an oxalate-degrading bacterium which was isolated from the feces of japanese male.19968646596
detection and chemical identification of natural bio-antimutagens. a case of the green tea factor.a bio-antimutagen, isolated from japanese green tea (leaves of camellia sinensis), reduced high spontaneous mutations due to altered dna-polymerase iii in a mutator strain of bacillus subtilis. chemical studies showed that the factor was epigallo-catechin-gallate (egcg).19853923334
isolation of camelliaside c from "tea seed cake" and inhibitory effects of its derivatives on arachidonate 5-lipoxygenase.a new flavonol glycoside, camelliaside c, was isolated from "tea seed cake" prepared from the defatted seeds of camellia sinensis o. kuntze. the structure was determined as kaempferol 3-o-beta-d-galactopyranosyl-(1-->2)-beta-d-glucopyranoside by spectroscopic methods (fab-ms, uv, ir, 1h- and 13c-nmr) and the enzymatic transformation of camelliaside c to astragalin. camelliaside c showed an inhibitory effect on the arachidonate 5-lipoxygenase of rbl-1 cells (ic50:1.4 x 10(-4)m) as did camelliasid ...19938370116
[effect of six edible plants on the development of afb1-induced gamma-glutamyltranspeptidase-positive hepatocyte foci in rats].six edible plants, green tea (gt), black tea (bt), lentinus edodes (berk) sing (le), hericium erinaceus (bull. ex fr.) pers. (he), mixture of ganoderma lucidum (ley ss ex fr.) karst et ganoderma japanium (fr.) lloyd (mglj) and mung bean (mb), were tested for the effect on the development of afb1-induced gamma-glutamyltranspeptidase positive hepatocyte foci (gamma-gt foci) using an in vivo short-term test model in rats. the rats received intraperitoneally 12 doses of initiator afb1, 400 microgram ...19872443327
prophylactic effect of tea on pathogenic micro-organism infection to human and animals. (1). growth inhibitive and bacteriocidal effect of tea on food poisoning and other pathogenic enterobacterium in vitro.0.5% tea powder of oolong tea, green tea and black tea, respectively added to tryptic soy agar (tsa) plates prepared non aseptically could inhibit the growth of colonies of st. aureus and airborne bacteria, but only very few fungi colonies. 0.5% tea powder of oolong tea, green tea and black tea, respectively added to tryptic soy agar (tsa) plates prepared non aseptically could also inhibit the colonial growth of v. cholerae, v. parahaemorrhagiae, sal. dysenteriae, sal. typhi, sal. paratyphi a an ...19807251263
antioxidative and antimutagenic effects of theaflavins from black tea.theaflavins, polyphenolic ingredients of black tea, were observed to inhibit in vitro lipid peroxidation in the erythrocyte membrane ghost and microsomal systems. theaflavins also showed inhibition of dna single-strand cleavage and mutagenicity, both induced by hydrogen peroxide. these results suggest that theaflavins scavenge radicals to produce antioxidative and antimutagenic effects. it was also found that the gallic acid moiety of theaflavins is essential for their potent antioxidative activ ...19947508563
k and ca content of fresh green tea, black tea, and tea residue determined by x-ray fluorescence analysis.x-ray fluorescence (xrf) can be successfully used for the qualitative and quantitative elemental analysis of various agricultural products. its simplicity, high throughput and the possibility of automation make it useful for screening large numbers of samples. the k and ca content of 138 samples of fresh green tea, black tea and black tea residues were determined by applying the xrf system. such a method of mineral analysis of food products is not very common. tea from different tea-growing area ...19938438623
effect of tea on iron absorption from the typical tunisian meal 'couscous' fed to healthy and green tea decoctions are popular beverages in tunisia, especially after eating. our study was performed to examine the effect of graded amounts of black and green tea decoction prepared under realistic tunisian conditions on nonheme iron absorption from a typical tunisian meal, 'couscous', by extrinsic radioiron labeling in rats. concentrations of 300, 200 and 100 micrograms/ml of black tea decreased dramatically nonheme iron bioavailability from couscous, but 50 micrograms/ml did not ...19947832583
enhancement of gap junctional intercellular communication in tumor promoter-treated cells by components of green tea (camellia sinensis) has been reported to inhibit tumor promotion in vivo and in vitro. many tumor promoters inhibit gap junctional intercellular communication (gjic) which may be an important mechanism of promotion. in the present study, we hypothesized that green tea would enhance gjic in promoter-treated cells. an aqueous extract of green tea (gte) and several of its constituents were tested for their effects on gjic in p,p'-dichlorodiphenyltrichloroethane (ddt)-, 12-o-tetradecanoylp ...19938481889
antibacterial effect of theaflavin, polyphenon 60 (camellia sinensis) and euphorbia hirta on shigella spp.--a cell culture study.antibacterial effect of compounds extracted from camellia sinensis l. and the methanol extract of euphorbia hirta l. were studied against dysentery causing shigella spp. using the vero cell line. cytotoxicity studies of the extracts were performed using the cell line and the non-cytotoxic concentration of the extract was tested for antibacterial activity against the cytopathic dose of the pathogen. these extracts were found to be non-cytotoxic and effective antibacterial agents.19958847884
effect of tea (camellia sinensis l.) on lipid peroxidation in rat liver and kidney: a comparison of green and black tea feeding.the antioxidant effects in the liver and kidney obtained from rat fed diets containing 3% green or black tea leaf powder, which were prepared from the same lot tea leaves, were studied using the tissue slice-antioxidant evaluation method with two lipid peroxidation inducers. after 50 d on the diets, liver slices prepared from green and black tea-supplemented rats showed significant inhibitory effects against tert-butyl hydroperoxide-induced lipid peroxidation. these effects, however, were not pr ...19957581239
gastro-intestinal availability of aluminium from tea.the in vitro speciation of aluminium (al) in black tea infusion (ph 4.8) was assessed using 3000, 10,000 and 30,000 da cut-off ultrafilters, and the effect of adding human gastric juice (ph 2.3) and then raising the ph to 6.5 were also studied. 78% al in the tea infusion passed through the 3000-da ultrafilter; this percentage increased to more than 90% with the addition of gastric juice at ph 2.3, but then reduced to approximately 5% when the incubate was adjusted to ph 6.5. the breakdown of tea ...19938514217
inhibitory effects of green tea polyphenols on growth and cellular adherence of an oral bacterium, porphyromonas gingivalis.effects of polyphenolic compounds isolated from green tea (camellia sinensis) on the growth and adherence of porphyromonas gingivalis onto human buccal epithelial cells were investigated. green tea polyphenols, especially (-)-epigallocatechin gallate (egcg) which is a dominant component of tea polyphenols, completely inhibited the growth and adherence of p. gingivalis onto the buccal epithelial cells at concentrations of 250-500 micrograms/ml. among the polyphenolic compounds, (-)-epicatechin ga ...19968704303
experimental studies on the treatment of frostbite in rats.the effect of treatment by high dose of vitamin c, rapid rewarming by 37 degrees c water alone and with vitamin c, rapid rewarming by 37 degrees c decoction of indian black tea alone and with vitamin c for experimentally produced frostbite was evaluated in 6 groups (25 each) of rats. frostbite was produced experimentally in the hind limbs by exposing the animals at -15 degrees c for 1h using the harness technique. the degree of injury was assessed and classified on the basis of tissue necrosis a ...19938262579
antioxidative effects of black tea theaflavins and thearubigin on lipid peroxidation of rat liver homogenates induced by tert-butyl hydroperoxide.the antioxidative activity of theaflavins (tfs) and thearubigin (tr) purified from the infusion of black tea leaves was examined using the tert-butyl hydroperoxide-induced lipid peroxidation of rat liver homogenates. the concentrations which produced 50% inhibition of lipid peroxidation (ic50) by theaflavin (tf), theaflavin monogallate-a (tfm-a), and tr were 4.88 x 10(-4), 4.09 x 10(-4), and 4.95 x 10(-4%) (w/v), respectively. the anti-oxidative activity of these compounds was higher than that o ...19948148805
inhibitory effect of tea catechins on collagenase activity.a major purpose of this study was to examine inhibitory effect of the catechin derivatives from japanese green tea camellia sinensis on collagenase activity. the crude tea catechins, which contain (+)-catechin (c), (-)-epicatechin (ec), (+)-gallocatechin (gc), (-)-epigallocatechin (egc), (-)-epicatechin gallate (ecg), and (-)-epigallocatechin gallate (egcg), were tested for their ability to inhibit the prokaryotic and eukaryotic cell derived collagenase activities. among the tea catechins tested ...19938396176
black tea, green tea, and tea polyphenols. effects on trace element status in weanling rats.previous studies have shown that tea consumption can impair trace element metabolism, particularly iron status, and increase the risk of anemia in humans and animals. more recently, however, evidence has been accumulating to show that, in animals, consumption of green tea or its polyphenols is associated with a reduction of the incidence and severity of a variety of experimentally induced cancers. in this study we have monitored the growth, trace element status, including hematological parameter ...19968862735
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 ...19968979512
dietary tannins from cowpeas and tea transiently alter apparent calcium absorption but not absorption and utilization of protein in rats.tannins reportedly alter absorption and utilization of protein and minerals. the present study investigated the effect of tannins extracted from 'mississippi silver' cowpeas and black tea when incorporated into nutritionally balanced diets. condensed tannins were incorporated into the diet of weanling male sprague-dawley rats at 0.0, 0.0057, 0.0171 and 0.057 g/100 g diet for 28 d. ingestion of tannin from cowpeas or tea did not change significantly growth rate, protein efficiency ratio, apparent ...19948308578
studies of cuticle drugs from natural sources. ii. inhibitory effects of prunus plants on melanin biosynthesis.the inhibitory effects of 50% ethanolic extracts from dried leaves of 38 plants collected in the herbal garden of kinki university were investigated in vitro on melanin biosynthesis which is closely related to hyperpigmentation. of the 38 extracts, prunus yedoensis, p. zippeliana, p. amygdalus, p. persica, p. armeniaca, thea sinensis and chaenomeles sinensis showed a potent inhibition of tyrosinase, the enzyme which converts 3-(3,4-dihydroxyphenyl)alanine (dopa) to dopachrome in the biosynthetic ...19947874069
endotoxin induced production of interleukin-6 is enhanced by vitamin e deficiency and reduced by black tea extract.studies were performed to investigate the effect of a polyphenol rich extract from black tea and vitamin e on bacterial lipopolysaccharide (endotoxin) induced il-6 production, alterations in liver glutathione and antioxidant acute phase protein (caeruloplasmin) concentration, in rats fed on a synthetic diet for 21 days. in the vitamin e sufficient group a significantly lower il-6 concentration than in vitamin e deficient animals was observed. addition of tea extract to the diet produced a simila ...19958564528
in vivo antioxidant effect of green and black tea in man.evaluation of the vitro antioxidant activity of green and black tea, their in vivo effect on plasma antioxidant potential in man and the effect of milk addition.19968617188
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 ...19979167003
tea and cancer.tea is one of the most popular beverages consumed worldwide. the relationship between tea consumption and human cancer incidence is an important concern. this topic has been studied in different populations by many investigators, but no clear-cut conclusion can be drawn. whereas some studies have shown a protective effect of tea consumption against certain types of cancers, other studies have indicated an opposite effect. our purpose is to provide a critical review of this topic, covering basic ...19938515490
tea polyphenols as inhibitors of mutagenicity of major classes of carcinogens.previous research suggested that the mutagenicity of some genotoxic carcinogens, mainly heterocyclic amines, was decreased by green or black tea extracts, or tea polyphenol fractions. thus, it seemed important to test a variety of genotoxic carcinogens with distinct chemical structures and means of biochemical activation as regards modification of mutagenicity in appropriate strains of salmonella typhimurium by 3 concentrations of polyphenols 60, 100, or b, standard commercial polyphenol prepara ...19968950350
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 ...19979209319
polyphenols as cancer chemopreventive agents.this article summarizes available data on the chemopreventive efficacies of tea polyphenols, curcumin and ellagic acid in various model systems. emphasis is placed upon the anticarcinogenic activity of these polyphenols and their proposed mechanism(s) of action. tea is grown in about 30 countries and, next to water, is the most widely consumed beverage in the world. tea is manufactured as either green, black, or oolong; black tea represents approximately 80% of tea products. epidemiological stud ...19958538195
[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 ...19979248263
caffeine induces cytochrome p4501a2: induction of cyp1a2 by tea in rats.previous reports indicated that treatment of rats with green tea or black tea extracts increased cyp1a2 activity, but such an induction was not observed with decaffeinated green tea in our preliminary study. herein we report a comparative study on the induction of cyp1a2 with different tea preparations and caffeine as an inducer. when green tea (2%) or black tea (2%) was given to male fischer 344 rats as the sole source of drinking fluid for 21 days, a 2.4- or 2.7-fold induction, respectively, o ...19968723732
dietary modulation of the carcinogenicity of the heterocyclic amines.heterocyclic amines (hcas) are potent mutagens and carcinogens formed during cooking of meats or fish. they are, therefore, widely consumed by humans.19958844815
a comparison of the antimutagenic potential of green, black and decaffeinated teas: contribution of flavanols to the antimutagenic effect.the present study was undertaken to compare the antimutagenic activity of aqueous extracts, at the concentrations used for human consumption, from green, black and decaffeinated black tea. antimutagenic potential was evaluated against three indirect-acting dietary carcinogens, glu-p-1, benzo(a)pyrene and nitrosopyrrolidine. all three types of tea gave rise to strong and concentration-dependent suppression of the mutagenicity of the three premutagens in the presence of an activation system. no ma ...19968962430
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 ...19979292413
the effect of teas on the in vitro mutagenic potential of heterocyclic aromatic amines.water extracts of eight brands (five types: 'green', 'black', 'oolong', decaffeinated and instant) of common teas (derived from camellia sinensis) and infusions of six randomly selected herbal teas were examined for inhibitory or potentiating effects on the mutagenicity of eight heterocyclic aromatic amines (haa) using the ames salmonella typhimurium ta98 and s-9 assay. haa, produced in foods during regular heat processing of meat, exhibit mutagenic/carcinogenic activities. tea extracts from c. ...19968690310
inhibitory effects of tea extracts and (-)-epigallocatechin gallate on dna synthesis and proliferation of hepatoma and erythroleukemia cells.polyphenols extracted from green or black tea with ethyl acetate were strongly inhibitory for dna synthesis in htc rat hepatoma cells and ds19 mouse erythroleukemia cells at concentrations of 0.1-0.2 mg/ml. there was less inhibition with a subsequent black tea fraction extracted with butanol and with the residual water-soluble fraction. although cell proliferation was inhibited by (-)-epigallocatechin gallate and the tea extracts, there were only marginal effects on differentiation of ds19 cells ...19938443796
protection by green tea, black tea, and indole-3-carbinol against 2-amino-3-methylimidazo[4,5-f]quinoline-induced dna adducts and colonic aberrant crypts in the f344 rat.male f344 rats were exposed for 8 weeks to extracts of green tea (2% w/v) or black tea (1% w/v), or to 0.1% dietary indole-3-carbinol (i3c). in weeks 3 and 4 of the study, rats were given 2-amino-3-methylimidazo[4,5-f]quinoline (iq) every other day by oral gavage (50 mg/kg body wt) in order to induce aberrant crypt foci (acf) in the colon. compared with controls given iq alone, all three inhibitors reduced the number of total aberrant crypts per colon, and green tea and i3c inhibited significant ...19968706244
inhibitory effect of six green tea catechins and caffeine on the growth of four selected human tumor cell tea is an aqueous infusion of dried unfermented leaves of camellia sinensis (family theaceae) from which numerous biological activities have been reported including antimutagenic, antibacterial, hypocholesterolemic, antioxidant, antitumor and cancer preventive activities. from the aqueous-alcoholic extract of green tea leaves, six compounds (+)-gallocatechin (gc), (-)-epicatechin (ec), (-)-epigallocatechin (egc), (-)-epicatechin gallate (ecg), (-)-epigallocatechin gallate (egcg) and caffei ...19968826614
prevention of heterocyclic amine formation by tea and tea polyphenols.heterocyclic amines (hcas), formed during the cooking of meats and fish, are thought to be the genotoxic carcinogens associated with important types of human cancer in meat-eating populations, such as cancer of the breast, colon or pancreas. we studied the effect of black or green tea, and of the tea polyphenols theaflavine gallate (tfg, black tea) and epigallocatechin gallate (egcg, green tea) on the formation of typical hcas, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (meiqx), and 2-amino-1 ...19948062207
effects of green tea and black tea on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone bioactivation, dna methylation, and lung tumorigenesis in a/j mice.previous studies in our laboratory showed that decaffeinated green tea and black tea extracts inhibited 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (nnk)-induced tumorigenicity in a/j female mice. in order to understand the mechanism of the inhibitory action, we examined the effects of decaffeinated green tea, black tea, and tea components on the metabolic activation of nnk in vitro and in vivo in this animal model. when added to incubation mixtures containing mouse lung microsomes, decaffein ...19948062257
the inhibitory effect of chinese tea and its polyphenols on in vitro and in vivo n-nitrosation.the objective of this study is to evaluate the possible role of chinese tea as a natural inhibitor of n-nitrosation, and to compare the relative inhibitory potency of various kinds of chinese tea in vitro and in vivo. studies on the inhibitory effect of 145 samples of chinese tea on the formation of n-nitrosomorpholine (nmor) showed that the inhibitory potency of the 7 types of chinese tea differed greatly, the average blocking rate of green tea (89.04%, n = 60), crush, tear, and curl (ctc) blac ...19938292269
relationship between antimutagenic activity and major components of various teas.the objectives of this study were to determine the major components in tea leaves and tea extracts and to study the relationship between chemical content and antimutagenic activity of various tea extracts. the amount of catechins in various tea extracts was in the order: green tea (26.7%) > oolong tea (23.2%) > pouchong tea (15.8%) > black tea (4.3%). the amounts of caffeine and phenolic compounds in oolong tea extracts were 8.3 and 32.4%, respectively; these amounts were greater than those in t ...19968671713
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 ...19978970175
inhibitory effects of tea catechins, black tea extract and oolong tea extract on hepatocarcinogenesis in rat.inhibitory effects of individual tea catechins ((--)-epicatechin, (--)-epigallocatechin, (--)-epicatechin gallate, (--)-epigallocatechin gallate), black tea extract and oolong tea extract on hepatocarcinogenesis were investigated. male f344 rats received a single dose of diethylnitrosamine (200 mg/kg, i.p.), and thereafter phenobarbital (0.05%) was administered in the drinking water for a period of 6 weeks. tea catechins, black tea extract or oolong tea extract were given during the entire exper ...19968957060
effect of flavan-3-ol tannins purified from camellia sinensis on lipid peroxidation of rat heart mitochondria.we induced lipid peroxidation in rat heart mitochondria with feso4 and compared the inhibitory effect of various flavan-3-ol tannins on it. these tannins were purified from chinese tea (camellia sinensis). oxygen consumption and malondialdehyde formation were used to quantitate the amount of lipid peroxidation. the free radical scavenger activity of tannins was then measured with a diphenyl-p-picrylhydrazyl method. these tannins significantly inhibited lipid peroxidation at micromolar concentrat ...19947872240
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