| tea as a potential chemopreventive agent in phip carcinogenesis: effects of green tea and black tea on phip-dna adduct formation in female f-344 rats. | the heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) is formed during the cooking of proteinaceous animal foods (meat, chicken, and fish). phip is a carcinogen in the fischer 344 (f-344) rat; it induces mammary tumors in female rats and lymphomas and colon and prostate tumors in male rats. in f-344 rats, phip forms dna adducts in various organs, including the target organs. inhibition of phip-dna adduct formation is likely to lead to inhibition of phip tumorigenicity. we ... | 2000 | 10798216 |
| acute effects of ingestion of black and green tea on lipoprotein oxidation. | tea has been associated with a reduced risk of cardiovascular disease. one proposed mechanism of this risk reduction involves inhibition of lipoprotein oxidation in vivo by antioxidant polyphenolic compounds derived from tea. however, controlled interventions uniformly failed to show that ingestion of tea can inhibit ldl oxidation ex vivo. the absence of effects in previous studies may be due to the isolation of ldl particles from polyphenolic compounds that are present in the aqueous phase of s ... | 2000 | 10799371 |
| catechin contents of foods commonly consumed in the netherlands. 2. tea, wine, fruit juices, and chocolate milk. | catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. to enable an epidemiological evaluation of catechins, data on their contents in foods are required. hplc with uv and fluorescence detection was used to determine the levels of (+)-catechin, (-)-epicatechin, (+)-gallocatechin (gc), (-)-epigallocatechin (egc), (-)-epicatechin gallate (ecg), and (-)-epigallocatechin gallate (egcg) in 8 types of black tea, 18 types of red and white wines, apple juice ... | 2000 | 10820090 |
| protease from sporosarcina sp. rrlj 1. | protease was isolated from sporosarcina rrlj1 which was collected from acid tea (camellia sinensis) plantations. it showed potential for production of the enzyme for commercial purposes. the study revealed that optimum ph for growth of the organism was 6.5-7 and supplement of casein (1%) in the medium was required for production of protease. enzyme production and enzyme activity was maximum in 72 hr old broth culture. maximum activity of the enzyme was found at ph 6.5. | 2000 | 10927879 |
| 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 |
| 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 |
| 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 |
| electrospray characterization of selected medicinal plant extracts. | extracts of selected medicinal plants were examined by electrospray mass spectrometry (esi-ms). this technique allowed identification of the main components of each extract, thereby providing a typical finger-print of the examined plants. more specifically, anthocyanins (vaccinium myrtillus), isoflavones (glycine max, soybean), flavonol-glycosides and terpenes (ginkgo biloba), triterpenes (centella asiatica), caffeoyl-quinic acids (cynara scolymus, artichoke), ginsenosides (panax ginseng), catec ... | 2000 | 10898155 |
| antimutagenic activity of green tea and black tea extracts studied in a dynamic in vitro gastrointestinal model. | an in vitro gastrointestinal model, which simulates the conditions in the human digestive tract, was used to determine potential antimutagenic activity of extracts of black tea and green tea. in this paper, results are presented on the availability for absorption of potential antimutagenic compounds present in tea and on the influence of the food matrix on this activity. between 60 and 180min after the tea was introduced into the model, antimutagenic activity was recovered from the jejunal compa ... | 2001 | 11239964 |
| kombucha, the fermented tea: microbiology, composition, and claimed health effects. | kombucha is a slightly sweet, slightly acidic tea beverage consumed worldwide, but historically in china, russia, and germany. kombucha is prepared by fermenting sweetened black tea preparations with a symbiotic culture of yeasts and bacteria. potential health effects have created an increased interest in kombucha. yet, only a few research studies have shown that kombucha has in vitro antimicrobial activity and enhances sleep and pain thresholds in rats. furthermore, kombucha consumption has pro ... | 2000 | 10914673 |
| marked reduction in the minimum inhibitory concentration (mic) of beta-lactams in methicillin-resistant staphylococcus aureus produced by epicatechin gallate, an ingredient of green tea (camellia sinensis). | we found that epicatechin gallate, a constituent of an extract of tea leaves (green tea) markedly lowered the minimum inhibitory concentration (mic) of oxacillin and other beta-lactams, but not of other antibacterial agents tested, in strains of methicillin-resistant staphylococcus aureus. the antibacterial action of epicatechin gallate plus oxacillin was a bactericidal one. | 1999 | 10746177 |
| flavonoids protect against oxidative damage to ldl in vitro: use in selection of a flavonoid rich diet and relevance to ldl oxidation resistance ex vivo? | the ability of a range of dietary flavonoids to inhibit low-density lipoprotein (ldl) oxidation in vitro was tested using a number of different methods to assess oxidative damage to ldl. overall quercetin was the most effective inhibitor of oxidative damage to ldl in vitro. on this basis, a diet enriched with onions and black tea was selected for a dietary intervention study that compared the effect on the cu2+ ion-stimulated lag-time of ldl oxidation ex vivo in healthy human subjects of a high ... | 2000 | 11022850 |
| anti-cariogenic properties of tea (camellia sinensis). | various components in green and black tea, the beverages made by infusing appropriately processed dried leaves of camellia sinensis, notably simple catechins, have properties in vitro that suggest an anti-cariogenic activity. these include: a direct bactericidal effect against streptococcus mutans and s. sobrinus; prevention of bacterial adherence to teeth; inhibition of glucosyl transferase, thus limiting the biosynthesis of sticky glucan; inhibition of human and bacterial amylases. studies in ... | 2001 | 11289514 |
| inhibition of 1,2-dimethylhydrazine-induced oxidative dna damage in rat colon mucosa by black tea complex polyphenols. | the effect of black tea polyphenols on 1,2-dimethylhydrazine (dmh)-induced oxidative dna damage in rat colon mucosa has been investigated. fischer 344 rats were treated orally with thearubigin (tr) or theafulvin (tfu) for 10 days (40 mg/kg), injected ip with dmh (20 mg/kg) or saline and sacrificed 24 hr after dmh administration. the levels of 8-hydroxy-2'-deoxyguanosine (8-ohdg) were measured in colonic mucosa dna and expressed as a ratio relative to 2'-deoxyguanosine (2dg). control rat mucosa h ... | 2000 | 11033196 |
| effects of black tea, green tea and wine extracts on intestinal carcinogenesis induced by azoxymethane in f344 rats. | we investigated whether polyphenolic extracts from black tea, green tea or red wine affect azoxymethane (aom)-induced intestinal carcinogenesis. male f344 rats were treated 10 times (1 week apart) with aom (7.4 mg/kg, s.c.) and then allocated into groups receiving black tea, green tea or red wine extracts mixed in the diet at a dose of 50 mg/kg body weight for 16 weeks. in the rats treated with black tea or wine extracts, there were significantly fewer colorectal tumours than in controls (the me ... | 2000 | 11062155 |
| effect of black and green tea polyphenols on c-jun phosphorylation and h(2)o(2) production in transformed and non-transformed human bronchial cell lines: possible mechanisms of cell growth inhibition and apoptosis induction. | the biological activities of theaflavin (tf), theaflavin gallate (tfg) and theaflavin digallate (tfdig) from black tea and (-)-epigallocatechin 3-gallate (egcg) and (-)-epigallocatechin (egc) from green tea were investigated using sv40-immortalized (33bes) and ha-ras gene transformed (21bes) human bronchial epithelial cell lines. growth inhibition and cell viability were measured by trypan blue dye exclusion assay following 24 h treatment with the tea polyphenols. tfdig, egc and egcg displayed c ... | 2000 | 11062165 |
| tea consumption modulates hepatic drug metabolizing enzymes in wistar rats. | the antioxidant, antimutagenic and anticarcinogenic activities of green tea and its polyphenols have been reported. as bioactivation of the precarcinogens and detoxification of ultimate carcinogens are mainly carried out by hepatic metabolizing enzymes, we have investigated the modulation of these enzyme activities subsequent to tea consumption in rats. female wistar rats were divided into eight groups (n = 5). six groups were given aqueous solutions (2%, w/v) of six different teas (new zealand ... | 2001 | 11341376 |
| inhibitory effects of tea catechins and o-methylated derivatives of (-)-epigallocatechin-3-o-gallate on mouse type iv allergy. | the inhibitory effects of tea catechins, the o-methylated derivatives of (-)-epigallocatechin-3-o-gallate (egcg), and the polyphenol extracts from tea leaves (camellia sinensis l.) on oxazolone-induced type iv allergy in male icr mice were investigated. four major tea catechins and two o-methylated derivatives, (-)-epigallocatechin-3-o-(3-o-methyl)gallate (egcg3' 'me) and (-)-epigallocatechin-3-o-(4-o-methyl)gallate (egcg4' 'me), showed significant inhibitory effects on mouse type iv allergy aft ... | 2000 | 11087533 |
| protection against nitric oxide toxicity by tea. | it is found that green tea and black tea are able to protect against nitric oxide (no(*)) toxicity in several ways. both green tea and black tea scavenge no(*) and peroxynitrite, inhibit the excessive production of no(*) by the inducible form of nitric oxide synthase (inos), and suppress the lps-mediated induction of inos. the no(*) scavenging activity of tea was less than that of red wine. the high activity found in the polyphenol fraction of black tea (btp) could not be explained by the mixed ... | 2000 | 11087552 |
| differential effects of theaflavin monogallates on cell growth, apoptosis, and cox-2 gene expression in cancerous versus normal cells. | theaflavin (tf-1), theaflavin-3-monogallate and theaflavin-3'-monogallate mixture (tf-2), and theaflavin-3,3'-digallate (tf-3) are the major black tea polyphenols. here we compared the effects of these polyphenols on cell growth, apoptosis, and gene expression in normal and cancerous cells. we showed that tf-2 (10-50 microm) inhibited the growth of sv40 transformed wi38 human cells (wi38va) and caco-2 colon cancer cells but had little effect on the growth of their normal counterparts. the ic50s ... | 2000 | 11103814 |
| inhibition of human ldl lipid peroxidation by phenol-rich beverages and their impact on plasma total antioxidant capacity in humans. | mounting evidence shows that phenol-rich beverages exert strong antioxidant activity. however, in vivo evidence has produced conflicting results. in the present study, we studied the impact of the ingestion of 300 ml of black and green tea, alcohol-free red wine, alcohol-free white wine, or water on plasma total antioxidant capacity in five healthy volunteers. red wine has the highest content of phenolics (3.63 +/- 0.48 g qe/l), followed by green tea (2.82 +/- 0.07 g qe/l), black tea (1.37 +/- 0 ... | 2000 | 11137897 |
| novel approaches to chemoprevention of skin cancer. | protection against sun-induced damage leading to photocarcinogenesis in skin is a highly desirable goal. among various strategies, chemopreventive approaches utilizing non-toxic agents to prevent the occurrence of precancerous lesions or their surrogate markers are potentially attractive. epidemiological and experimental studies provide evidence that some naturally occurring chemical agents in the human diet can diminish cancer risk. aside from water, tea is the most common beverage consumed wor ... | 2000 | 11138532 |
| effect of dietary quercetin on oxidative dna damage in healthy human subjects. | the effect of dietary intake of flavonols (predominantly quercetin) on oxidative dna damage was studied in thirty-six healthy human subjects (sixteen men, twenty women). the study was a randomised crossover study, comprising two 14 d treatments of either a low-flavonol (lf) or high-flavonol (hf) diet with a 14 d wash-out period between treatments. subjects were asked to avoid foods containing flavonols, flavones and flavanols during the lf dietary treatment period and to consume one 150 g onion ... | 2000 | 11177210 |
| green, oolong and black tea extracts modulate lipid metabolism in hyperlipidemia rats fed high-sucrose diet. | the main goal of this study was to compare effects of ethanol-soluble fractions prepared from various types of teas on sucrose-induced hyperlipidemia in 5-week old male sprague-dawley rats. rats (n = 6-8 per group) weighed approximately 200 g were randomly divided into control diet, sucrose-rich diet, green tea, oolong tea and black tea groups. control-diet group was provided with modified ain-93 diet while the others consumed sucrose-rich diet. tea extracts (1% w/v) were supplied in the drink f ... | 2001 | 11179857 |
| inhibition of ultraviolet b-induced ap-1 activation by theaflavins from black tea. | theaflavins are believed to be key active components in black tea for chemoprevention of cancer. however, the molecular mechanisms underlying the inhibitory effects of theaflavins are not clear. with the jb6 mouse epidermal cell line, we investigated the effects of theaflavins on ultraviolet (uv) b radiation-induced activator protein-1 (ap-1)-dependent transcriptional activation and compared them with (-)-epigallocatechin-3-gallate (egcg), a major green tea polyphenol that has cancer chemopreven ... | 2000 | 10942531 |
| green tea. | tea is one of the most widely consumed beverages in the world today, second only to water, and its medicinal properties have been widely explored. the tea plant, camellia sinensis, is a member of the theaceae family, and black, oolong, and green tea are produced from its leaves. it is an evergreen shrub or tree and can grow to heights of 30 feet, but is usually pruned to 2-5 feet for cultivation. the leaves are dark green, alternate and oval, with serrated edges, and the blossoms are white, frag ... | 2000 | 10956382 |
| effect of black tea on lipid peroxidation in carbon tetrachloride treated male rats. | this study examined the effects of black tea (camellia sinensis l.) on lipid peroxidation and glutathione levels in carbon tetrachloride (ccl4)-treated male wistar rats. three groups of rats formed two control groups and one treatment group. the control groups were fed with a standard diet, while the black tea group were fed the standard diet plus 6% by weight dried black tea leaves. after two months, the rats in the black tea group and in one control group were administered a single dose of ccl ... | 2000 | 10962644 |
| black tea extract, thearubigin fraction, counteract the effects of botulinum neurotoxins in mice. | botulinum neurotoxin type a (bont/a, 1.5 nm) completely inhibited indirectly evoked twitches in in vitro mouse phrenic nerve-diaphragm preparations within 40 - 45 min. black tea extract, thearubigin fraction (trb), mixed with bont/a blocked the inhibitory effect of the toxin. the protective effect of trb extended to botulinum neurotoxins types b and e (bont/b and bont/e) and tetanus toxin, but not to tetrodotoxin. trb was also effective against oral toxicity of bont/a, b and e. thus, trb may be ... | 2001 | 11181419 |
| inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. | the effects of different polyphenol-containing beverages on fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-fe. the test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (matricaria recutita l.), vervain (verbena officinalis l.), lime flower (tilia cordata mill.), pennyroyal (mentha pulegium l.) and peppermint (mentha ... | 1999 | 10999016 |
| fumonisins b1 and b2 in black tea and medicinal plants. | fumonisins are mycotoxins produced by fusarium moniliforme that are prevalent in cereals and other agricultural products. these mycotoxins have been pointed to as a natural cause of equine leukoencephalomalacia, porcine pulmonary edema, and human esophageal cancer. a total of 87 samples, 18 black tea samples and 69 samples of four different medicinal plants (chamomile, leaves of the orange tree, leaves and flowers of the linden tree, and corn silk), for infusions preparations were acquired from ... | 2001 | 11510675 |
| effects of black tea extract on transplantable and solid tumors in swiss albino mice. | the chemopreventive effects of green tea and its polyphenols are well documented in the literature. epidemiological studies have suggested that green tea consumption might be effective in the prevention of certain human cancers. about 80% of the tea is consumed as black tea. limited studies have been carried out to assess the usefulness of black tea as anti-carcinogen. the present set of investigations were initiated to study the anti-tumorigenic potential of aqueous black tea extract (ate) in s ... | 2000 | 11198223 |
| 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 |
| effect of black tea on lipid peroxide and glutathione levels in female rats. | the effects of black tea (camellia sinensis l.) on lipid peroxidation and glutathione (gsh) levels in carbon tetrachloride (ccl4)-treated female wistar rats were examined. two control groups and one treatment group were tested. the control groups were fed with a standard diet, while the black tea group was fed the standard diet plus 6% by weight dried black tea leaves. at the end of 2 months, a single dose of ccl4 (1 ml/kg, i.p.) in olive oil was administered to rats in one of the control groups ... | 2000 | 11201308 |
| an approach to cancer risk assessment for the food constituent 2-hexenal on the basis of 1,n2-propanodeoxyguanosine adducts of 2-hexenal in vivo. | 2-hexenal is formed by plants, and humans are regularly exposed to this mutagenic/genotoxic compound via vegetable foods. 2-hexenal has not been tested for carcinogenicity, but it forms exocyclic 1,n2-propanodeoxyguanosine adducts like other carcinogenic alpha,beta-unsaturated carbonyl compounds. to quantify the respective dna adducts as an approach to a theoretical cancer risk assessment, we used a newly developed 32p-postlabelling technique based on nuclease p1 enrichment, allowing a detection ... | 2000 | 11201673 |
| mechanisms of inhibition of carcinogenesis by tea. | tea (camellia sinensis) preparations have been shown to inhibit tumorigenesis at the initiation, promotion, and progression stages in different animal models. the anti-proliferative effects of tea polyphenols may be a key mechanism, especially in the nnk-induced lung tumorigenesis model with mice. studies with cell lines have demonstrated that tea polyphenols inhibit cell proliferation and induce apoptosis. the effective concentrations used in these studies (20-100 microm) are usually higher tha ... | 2000 | 11237203 |
| tea catechins and related polyphenols as anti-cancer agents. | epigallocatechin gallate (egcg) and theaflavins, a major constituent of green tea infusion and the constituents of black tea, respectively, were found to inhibit matrix metalloproteinases (mmps) which are intimately associated with tumor invasion and metastasis. egcg and related polyphenols exhibited apoptosis-inducing activity for several cancer cell lines including human stomach and colon cancer cells. comparison of the activity of these compounds revealed the importance of the number and the ... | 2000 | 11237204 |
| apoptosis-inducing activity of high molecular weight fractions of tea extracts. | high molecular weight fractions of green tea, black tea, oolong tea, and pu-erh tea were found to induce apoptosis in human monoblastic leukemia u937 cells by examination of their ability to inhibit cell proliferation and to induce apoptotic body formation and dna ladder formation. these tea fractions were also shown to induce apoptosis in stomach cancer mkn-45 cells. in addition to known antitumor-promoting activity of tea high molecular weight fractions, their apoptosis-inducing activity may c ... | 2001 | 11302190 |
| effects of (-)-epigallocatechin-3-gallate, the main component of green tea, on the cloned rat brain kv1.5 potassium channels. | the interaction of (-)-epigallocatechin-3-gallate (egcg), the main component of green tea (camellia sinensis), with rat brain kv1.5 channels (rkv1.5) stably expressed in chinese hamster ovary (cho) cells was investigated using the whole-cell patch-clamp technique. egcg inhibited rkv1.5 currents at +50 mv in a concentration-dependent manner, with an ic50 of 101.2+/-6.2 microm. pretreatment with protein tyrosine kinase (ptk) inhibitors (10 microm genistein, 100 microm ag1296), a tyrosine phosphata ... | 2001 | 11585049 |
| induction of apoptosis by the oolong tea polyphenol theasinensin a through cytochrome c release and activation of caspase-9 and caspase-3 in human u937 cells. | this study examined the growth inhibitory effects of theasinensin a (from oolong tea) and black tea polyphenols, including theaflavin (tf-1), a mixture (tf-2) of theaflavin-3-gallate (tf-2a) and theaflavin-3'-gallate (tf-2b), and theaflavin-3,3'-digallate (tf-3) in human cancer cells. theasinensin a, tf-1, and tf-2 displayed strong growth inhibitory effects against human histolytic lymphoma u937, with estimated ic50 values of 12 microm, but were less effective against human acute t cell leukemia ... | 2000 | 11312805 |
| determination of total aluminum, chromium, copper, iron, manganese, and nickel and their fractions leached to the infusions of black tea, green tea, hibiscus sabdariffa, and ilex paraguariensis (mate) by eta-aas. | total aluminum, chromium, copper, iron, manganese, and nickel were determined in black tea, green tea, hibiscus sabdariffa, and ilex paraguariensis (mate) by electrothermal atomic absorption spectrometry after nitric/perchloric acid digestion. in each case, one ground sample of commercially available leafy material was prepared and three 0.5-g subsamples were run in parallel. the infusions were also analyzed and the percentage of each element leached into the liquor was evaluated. the obtained r ... | 2000 | 11314985 |
| tea flavonoids and cardiovascular health. | tea is rich in antioxidant polyphenols (catechins, flavonols, theaflavins and thearubigins). epidemiological evidence relating regular consumption of tea or related polyphenols to chd is equivocal. catechins are absorbed from tea, but low plasma concentrations are attained. the bioavailability of theaflavins and thearubigins is unknown. tea does not reduce blood pressure or plasma lipids in well-controlled human trials. tea polyphenols inhibit ldl lipid peroxidation in vitro, but the effect ex v ... | 2001 | 11353103 |
| black tea is a powerful chemopreventor of reactive oxygen and nitrogen species: comparison with its individual catechin constituents and green tea. | production of black tea [bt] results in biotransformation of catechins of green tea [gt] to theaflavins and thearubigins. bt was found to be more efficient than gt and its individual catechin constituents in proportionate amounts in abrogating production of no and o2(-) in activated murine peritoneal macrophages. in a reconstitution system of bt that is free of all catechins, stepwise addition of catechins showed that though all the constituents contributed to the overall effect of bt, theaflavi ... | 2001 | 11374887 |
| role of reduced glutathione and nitric oxide in the black tea extract-mediated protection against ulcerogen-induced changes in motility and gastric emptying in rats. | the aim of the present study was to investigate the underlying mechanism of the role of hot water extract of black tea [camellia sinensis (l). o. kuntze theaceae] in normalizing the changes in intestinal transit and gastric emptying induced by various ulcerogenic agents in experimental rats. intestinal transit as well as gastric emptying were significantly reduced in rats treated with glutathione (gsh) depleting agents, diethyl maleate (dem), indoacetamide (ida) and n-ethyl maleimide (nem). prio ... | 2001 | 11388638 |
| distribution characteristics of fluoride and aluminum in soil profiles of an abandoned tea plantation and their uptake by six woody species. | distribution characteristics of fluoride (f) and aluminum (al) in soil profiles of an abandoned tea plantation in hong kong and their uptake by six woody species namely camellia sinensis, melastoma affine, sterculia lanceolata, ardisia crenata, acacia formosa and machilus thunbergii were investigated. c. sinensis accumulated both f (656 mg/kg in the leaves) and al (8910 mg/kg in the leaves). m. affine only accumulated al (9932 mg/kg in the leaves), while s. lanceolata, a. crenata, a. formosa and ... | 2001 | 11392749 |
| black tea extract, thearubigin fraction, counteracts the effect of tetanus toxin in mice. | the aim of this study was to find an inactivating substance for tetanus toxin in natural foodstuff. tetanus toxin (4 micrograms/ml) abolished indirect twitches in in vitro mouse phrenic nerve-diaphragm preparations within 2.5 hr. hot water infusion of black tea mixed with tetanus toxin blocked the inhibitory effect of the toxin. mixing the toxin with thearubigin fraction extracted from black tea infusion produced an identical result. furthermore, thearubigin fraction mixed with the toxin protect ... | 2001 | 11395929 |
| combination effect of lignin f and natural products. | we investigated the effect of lignin f, isolated from the alkaline extract of the cone of pinus parviflora sieb. et zucc, on the cytotoxic activity and radical intensity (measured by esr spectroscopy) of various natural products. lignin f slightly inhibited the proliferation of human oral tumor cell lines (human squamous cell carcinoma hsc-2, human salivary gland tumor hsg), but not that of human gingival fibroblast hgf, suggesting its tumor specific cytotoxic action. lignin f enhanced the cytot ... | 2001 | 11396189 |
| spectrophotometric determination of the tannin contents of various turkish black tea, beer and wine samples. | this study reports tannin contents of various tea (19), beer (6) and wine (6) samples, produced or sold in turkey under different brand names. determinations were carried out by employing a previously reported uv-vis spectrophotometric method. the standard addition procedure was also compared to the direct determination procedure and found to be more reliable. the tannin contents of hot water extracts of tea, tea bag and herbal tea samples ranged between 6.20-8.33, 8.03-6.59 and 2.76-6.54 percen ... | 2001 | 11400478 |
| flavonoid (myricetin, quercetin, kaempferol, luteolin, and apigenin) content of edible tropical plants. | studies were conducted on the flavonoids (myricetin, quercetin, kaempferol, luteolin, and apigenin) contents of 62 edible tropical plants. the highest total flavonoids content was in onion leaves (1497.5 mg/kg quercetin, 391.0 mg/kg luteolin, and 832.0 mg/kg kaempferol), followed by semambu leaves (2041.0 mg/kg), bird chili (1663.0 mg/kg), black tea (1491.0 mg/kg), papaya shoots (1264.0 mg/kg), and guava (1128.5 mg/kg). the major flavonoid in these plant extracts is quercetin, followed by myrice ... | 2001 | 11410016 |
| antioxidative activities of phenylethanoid glycosides from ligustrum purpurascens. | tea and kudingcha (bitter tea) are the two most popular beverages consumed in china. tea derived from the leaves of camellia sinensis has been well studied for its various health benefits, but there are very limited data on the biological activities of bitter tea derived from the leaves of ligustrum purpurascens (lp). the present study was carried out to characterize the antioxidants present in the bitter tea brewed from the leaves of lp. it was found that the crude glycoside fraction possessed ... | 2001 | 11410017 |
| inhibitory effects of orally administered green tea, black tea, and caffeine on skin carcinogenesis in mice previously treated with ultraviolet b light (high-risk mice): relationship to decreased tissue fat. | treatment of skh-1 hairless mice with ultraviolet b light (uvb; 30 mj/cm(2)) twice a week for 22 weeks resulted in tumor-free animals with a high risk of developing malignant and nonmalignant skin tumors during the next several months in the absence of additional uvb treatment (high-risk mice). oral administration of green tea or black tea (6 mg tea solids/ml) to uvb-pretreated high-risk skh-1 mice for 23 weeks after stopping uvb treatment decreased the number of tumors/mouse, decreased the size ... | 2001 | 11431333 |
| the distribution of minerals and flavonoids in the tea plant (camellia sinensis). | camellia sinensis is a plant growing in india, sri lanka, java, japan and its properties were known 4000 years ago. since then, traditional chinese medicine has recommended this plant for headaches, body aches and pains, digestion, depression, detoxification, as an energiser and, in general, to prolong life. tea contains volatile oils, vitamins, minerals, purines, polyphenols, particularly carechins. we have analysed ten commercial teas from various countries to determine their mineral compositi ... | 2001 | 11482766 |
| green tea extracts decrease carcinogen-induced mammary tumor burden in rats and rate of breast cancer cell proliferation in culture. | epidemiological evidence suggests tea (camellia sinensis l.) has chemopreventive effects against various tumors. green tea contains many polyphenols, including epigallocatechin-3 gallate (egcg), which possess anti-oxidant qualities. reduction of chemically induced mammary gland carcinogenesis by green tea in a carcinogen-induced rat model has been suggested previously, but the results reported were not statistically significant. here we have tested the effects of green tea on mammary tumorigenes ... | 2001 | 11500915 |
| antioxidant properties of green and black tea, and their potential ability to retard the progression of eye lens cataract. | aqueous extracts of green and black tea are shown to quench reactive oxygen species such as singlet oxygen, superoxide and hydroxyl radicals, prevent the oxidative cross-linking of test proteins and inhibit single strand breakage of dna in whole cells. they are also seen to be able to counteract the oxidative insult mounted by cigarette smoke. in rats in which cataract was induced by subcutaneous injection of selenite, administration of green or black tea extracts led to a retardation of the pro ... | 2001 | 11520114 |
| induction of apoptosis and cell cycle arrest in cancer cells by in vivo metabolites of teas. | the present study was conducted to determine in vivo possibilities of inducing apoptosis and cell cycle arrest in rat cancer cells by green, oolong, and black teas and also to further identify the mechanisms inhibiting cancer cell proliferation by the sera from tea-treated rats. the tea extracts from these three kinds of tea, the rat sera obtained after oral intubation of the tea extracts, and the tea polyphenolic compounds, (-)-epigallocatechin-3-gallate, (-)-epigallocatechin, (-)-epicatechin-3 ... | 2000 | 11525605 |
| anticariogenic effects of black tea (camellia sinensis) in caries prone-rats. | black tea (camellia sinensis) may have anticariogenic properties. the present study was designed to determine whether consumption of black tea influences cariogenesis in young, caries-prone rats. | 2001 | 11526894 |
| analysis of theaflavins in biological fluids using liquid chromatography-electrospray mass spectrometry. | a hplc-ms procedure for the sensitive and specific analysis of the black tea flavonoid theaflavin in human plasma and urine was developed. levels were measured after enzymatic deconjugation, extraction into ethyl acetate, and separation by hplc, using tandem mass spectrometry as a detecting system. two healthy volunteers consumed 700 mg theaflavins, equivalent to about 30 cups of black tea. the maximum concentration detected in blood plasma was 1.0 microg l(-1) in a sample collected after 2 h. t ... | 2001 | 11530986 |
| the effects of phenolic components of tea on the production of pro- and anti-inflammatory cytokines by human leukocytes in vitro. | epidemiological evidence suggests protective effects of dietary flavonoids against cardiovascular disease. tea provides a major source of dietary flavonoids in many countries and its polyphenolic components have well-recognised antioxidant properties. however, scavenging of free radicals may not be the sole mechanism by which tea-derived polyphenols exert their protective effects. this study investigates the effects of four major tea-derived catechins and a black tea extract on the production of ... | 2001 | 11243706 |
| addition of milk does not affect the absorption of flavonols from tea in man. | tea is a major source of flavonols, a subclass of antioxidant flavonoids present in plant foods which potentially are beneficial to human health. milk added to tea, a frequent habit in the united kingdom, could inhibit absorption of tea flavonoids, because proteins can bind flavonoids effectively. eighteen healthy volunteers each consumed two out of four supplements during three days: black tea, black tea with milk, green tea and water. a cup of the supplement was consumed every 2 hours each day ... | 2001 | 11264903 |
| antiinflammatory and antioxidant property of saponins of tea [camellia sinensis (l) o. kuntze] root extract. | two groups of saponins, ts-1 and ts-2, isolated from tea root extract (tre) were tested for antiinflammatory and in vitro antioxidant activity. both ts-1 and ts-2 inhibited carrageenan-induced paw oedema in rats. the antioxidant activity of these compounds was evaluated using the xanthine-xanthine oxidase system. the study indicated that the previously observed antitumour activity of tre might be mediated through scavenging of free radicals by saponins and their antiinflammatory activity. | 2001 | 11268124 |
| chemoprevention of basal cell carcinomas in the ptc1+/- mouse--green and black tea. | skin cancers are a rising menace as their incidence increases, attributed in part to increasing ultraviolet radiation exposure. this increasing problem has stimulated efforts to devise useful preventive approaches. the uncertain efficacy of exhortations to avoid sun exposure and to use protective clothing and sunscreens to reduce damage when exposed argue for the development of an oral chemopreventive agent. bickers and others have studied the effects and mechanisms of tea and of its putative ac ... | 2001 | 11598435 |
| effect of herbal teas on hepatic drug metabolizing enzymes in rats. | we have investigated the effect of herbal teas (peppermint, chamomile and dandelion) on the activity of hepatic phase i and phase ii metabolizing enzymes using rat liver microsomes. female wistar rats were divided into six groups (n = 5 each). three groups had free access to a tea solution (2%) while the control group had water. two groups received either green tea extract (0.1%) or aqueous caffeine solution (0.0625%). after four weeks of pretreatment, different cytochrome p450 (cyp) isoforms an ... | 2001 | 11697539 |
| effects of purified green and black tea polyphenols on cyclooxygenase- and lipoxygenase-dependent metabolism of arachidonic acid in human colon mucosa and colon tumor tissues. | the effects of green and black tea polyphenols on cyclooxygenase (cox)- and lipoxygenase (lox)-dependent arachidonic acid metabolism in normal human colon mucosa and colon cancers were investigated. at a concentration of 30 microg/ml, (-)-epigallocatechin-3-gallate (egcg), (-)-epigallocatechin (egc), and (-)-epicatechin-3-gallate (ecg) from green tea and theaflavins from black tea inhibited lox-dependent activity by 30-75%. the formation of 5-, 12-, and 15-lox metabolites was inhibited to a simi ... | 2001 | 11705450 |
| aqueous extracts of crinum latifolium (l.) and camellia sinensis show immunomodulatory properties in human peripheral blood mononuclear cells. | in vietnamese and chinese traditional medicine, hot aqueous extract of crinum latifolium is used because of its antitumor activity. the genus crinum is thought to possess antiviral and immunostimulative properties. green and black tea derived from camellia sinensis have similar qualities. a growing body of evidence suggests that moderate consumption of green and black tea may protect, e.g., against several forms of cancer, cardiovascular diseases, and bacterial infections. in this study, the imm ... | 2001 | 11710543 |
| effects of tea components on the response of gaba(a) receptors expressed in xenopus oocytes. | to study the effects of tea components on ionotropic gamma-aminobutyric acid (gaba) receptor response, ionotropic gaba receptors (gaba(a) receptors) were expressed in xenopus oocytes by injecting crnas synthesized from cloned cdnas of the alpha(1) and beta(1) subunits of the bovine receptors, and their electrical responses were measured by a voltage clamping method. extracts of green tea, black tea, and oolong tea in an aqueous solution induced the gaba-elicited response, which showed that these ... | 2002 | 12083865 |
| green tea upregulates the low-density lipoprotein receptor through the sterol-regulated element binding protein in hepg2 liver cells. | green tea from camellia sinensis lowers plasma cholesterol in animal models of hypercholesterolemia. the aim of this study was to determine the effects of green tea on the expression of the hepatic low-density lipoprotein (ldl) receptor, a cell surface protein involved in the control of plasma cholesterol. incubating human hepg2 liver cells in culture with green tea increased both ldl receptor binding activity and protein. an ethyl acetate extract of green tea, containing 70% (w/w) catechins, al ... | 2001 | 11714371 |
| inhibitory effects of polyphenolic catechins from chinese green tea on hiv reverse transcriptase activity. | three polyphenolic catechins, epigallocatechin (1), epicatechin-3-o-gallate (2) and epigallocatechin-3-o-gallate (3), were isolated from chinese green tea, ti-kaun-yin (camellia sinensis) and demonstrated as a new class of human immunodeficiency virus-reverse transcriptase (hiv-rt) inhibitor. the concentrations required for 50% inhibition for the compounds (1), (2) and (3) were 7.80, 0.32 and 0.68 &mgr;m, respectively. the polyphenolic catechins with a galloyl group at the 3 position were potent ... | 1994 | 11725021 |
| gastrointestinal enhancement of mri with melanin derived from tea leaves (thea sinensis linn.). | melanin was extracted from tea leaves (thea sinensis linn.) for the first time. characterization of melanin proved similarity of the original compound to standard melanin. the langmuir adsorption isotherms for gadolinium (gd) binding were obtained using melanin. melanin-gd preparation demonstrated low acute toxicity. ld(50) for this preparation was in a range of 1250-1500 mg/kg in mice. magnetic resonance imaging (mri) properties of melanin itself and melanin-gd complexes have been estimated. gd ... | 2002 | 11744298 |
| black tea polyphenols, theaflavins, prevent cellular dna damage by inhibiting oxidative stress and suppressing cytochrome p450 1a1 in cell cultures. | tea polyphenols have been demonstrated as chemopreventive agents in a number of experimental models. however, less is known about the mechanism of chemoprevention by black tea compared with that of green tea. some beneficial properties of theaflavins, the black tea polyphenols, were investigated in the present study. theaflavins showed inhibitory effects on h(2)o(2)- and tert-butyl hydroperoxide (tbuooh)-induced cytotoxicity (evaluated by tetrazolium bromide reduction), cellular oxidative stress ... | 2002 | 11754570 |
| attenuation of 6-hydroxydopamine (6-ohda)-induced nuclear factor-kappab (nf-kappab) activation and cell death by tea extracts in neuronal cultures. | antioxidant and anti-inflammatory therapy approaches have been in the focus of attention in the treatment of neurodegenerative parkinson's and alzheimer's diseases where oxidative stress has been implicated. tea extracts have been previously reported to possess radical scavenger, iron chelating and anti-inflammatory properties in a variety of tissues. the purpose of this study was to investigate potential neuroprotective effects of tea extracts and possible signal pathway involved in a neuronal ... | 2002 | 11754870 |
| black tea polyphenols inhibit igf-i-induced signaling through akt in normal prostate epithelial cells and du145 prostate carcinoma cells. | tea polyphenols have been proposed as potential chemopreventive agents against prostate cancer, primarily because of their high intake by populations with reduced cancer incidence and their reported ability to inhibit proliferation and increase apoptosis in prostate cancer cells in culture. insulin-like growth factor-i (igf-i) has been implicated as a risk factor for the development of prostate cancer by epidemiological studies and has been shown to be causative in animal models. one of the prim ... | 2002 | 11756245 |
| anticarcinogenic effect of black tea on pulmonary tumors in swiss albino mice. | the widespread consumption of tea as beverage throughout the world has stimulated interest in the possibility of its use in chemoprevention of cancer. the present set of investigation was carried out to evaluate the anticarcinogenic activity of black tea using lung tumorigenesis model in swiss albino mice. diethylnitrosoamine (den), a known inducer of pulmonary tumors was given at the multiple (total eight) doses of 20mg/kg body weight through oral intubation to swiss albino mice. simultaneously ... | 2002 | 11804740 |
| diurnal variation of photosynthesis and photoinhibition in tea: effects of irradiance and nitrogen supply during growth in the field. | diurnal changes in the rate of photosynthesis (a) of mature tea (camellia sinensis (l.) o. kuntze) bushes grown at high elevation in the field in sri lanka, were related to environmental conditions. bushes were either unshaded, receiving 100% of incident photosynthetically active radiation (par), moderately shaded, (65% par) or heavily shaded (30% par). these treatments were combined with nitrogen fertilizer applications of 0, 360 and 720 kg ha(-1) year(-1). when recently fully expanded leaves w ... | 2002 | 11807135 |
| inhibition of carcinogenesis by tea. | tea has received a great deal of attention because tea polyphenols are strong antioxidants, and tea preparations have inhibitory activity against tumorigenesis. the bioavailability and biotransformation of tea polyphenols, however, are key factors limiting these activities in vivo. the inhibition of tumorigenesis by green or black tea preparations has been demonstrated in animal models on different organ sites such as skin, lung, oral cavity, esophagus, forestomach, stomach, small intestine, col ... | 2002 | 11807163 |
| protection by beverages, fruits, vegetables, herbs, and flavonoids against genotoxicity of 2-acetylaminofluorene and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip) in metabolically competent v79 cells. | chinese hamster lung fibroblasts, genetically engineered for the expression of rat cytochrome p450 dependent monooxygenase 1a2 and rat sulfotransferase 1c1 (v79-rcyp1a2-rsult1c1 cells), were utilized to check for possible protective effects of beverages of plant origin, fruits, vegetables, and spices against genotoxicity induced by 2-acetylaminofluorene (aaf) or 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (phip). antigenotoxic activities of juices from spinach and red beets against aaf could ... | 2002 | 12438004 |
| accumulation of epigallocatechin quinone dimers during tea fermentation and formation of theasinensins. | production and accumulation of catechin dimer quinones during tea fermentation were chemically confirmed for the first time by trapping as phenazine derivatives. direct treatment of the fermented tea leaves with o-phenylenediamine yielded five phenazine derivatives (8-12) of o-quinones of an epigallocatechin dimer and its galloyl esters (13-16), in which two flavan units were linked at the b-rings through a c-c bond. atrop isomerism of the biphenyl bonds was shown to be the r configuration, sugg ... | 2002 | 12444680 |
| tea flavonoids: bioavailability in vivo and effects on cell signaling pathways in vitro. | the elucidation of the potential health benefits of tea beverage continues to be a focus of research in many laboratories. beneficial effects of tea have been particularly evident in animal tumorigenesis models, with green and black tea frequently demonstrating similar effectivity. human data are now emerging to support a beneficial role for tea in cardiovascular disease, but the data with respect to cancer risk at various sites remain inconclusive. the constituent flavonoids of green and black ... | 2001 | 11813977 |
| interactions between flavonoids and proteins: effect on the total antioxidant capacity. | flavonoids are potent antioxidants. it is also known that flavonoids bind to proteins. the effect of the interaction between tea flavonoids and proteins on the antioxidant capacity was examined. their separate and combined antioxidant capacities were measured with the trolox equivalent antioxidant capacity (teac) assay. it was observed that the antioxidant capacity of several components of green and black tea with alpha-, beta-, and kappa-casein or albumin is not additive; that is, a part of the ... | 2002 | 11853501 |
| catechins from green tea (camellia sinensis) inhibit bovine and human cartilage proteoglycan and type ii collagen degradation in vitro. | polyphenolic compounds from green tea have been shown to reduce inflammation in a murine model of inflammatory arthritis, but no studies have been undertaken to investigate whether these compounds are protective to joint tissues. we therefore investigated the effects of catechins found in green tea on cartilage extracellular matrix components using in vitro model systems. bovine nasal and metacarpophalangeal cartilage as well as human nondiseased, osteoarthritic and rheumatoid cartilage were cul ... | 2002 | 11880552 |
| antibacterial activity of black tea (camelia sinensis) extract against salmonella serotypes causing enteric fever. | alcoholic extract of black tea (camelia sinensis) was assayed for its antibacterial activity against salmonella serotypes causing enteric fever viz., salmonella typhi and salmonella paratyphi a. while all strains of s. paratyphi a tested were found sensitive, only 42.19% of s. typhi strains were inhibited by this extract. further minimum inhibitory concentration (mic) and minimum bactericidal concentration (mbc) of black tea extract against s. paratyphi a was less compared with that against s. t ... | 2001 | 11883337 |
| acute effects of ingestion of black tea on postprandial platelet aggregation in human subjects. | results of population studies suggest that black tea can reduce cardiovascular risk. effects of black-tea polyphenols to reduce platelet aggregability may help to explain any benefits. given that black tea is often consumed with and after meals, and man spends much of his life in the postprandial state, the objective of the present study was to investigate the acute effects of ingestion of black tea on postprandial platelet aggregation ex vivo. twenty healthy participants had platelet aggregatio ... | 2002 | 11895166 |
| theaflavins in black tea and catechins in green tea are equally effective antioxidants. | green tea catechins, including (-)-epicatechin (ec), (-)-epicatechin gallate (ecg), (-)-epigallocatechin (egc) and (-)-epigallocatechin gallate (egcg), are oxidized and dimerized during the manufacture of black tea and oolong tea to form orange-red pigments, theaflavins (tf), a mixture of theaflavin (tf1), theaflavin-3-gallate (tf2a), theaflavin-3'-gallate (tf2b) and theaflavin-3,3'-digallate (tf3). the present study was designed to compare the antioxidant activities of individual tf with that o ... | 2001 | 11533262 |
| catechins are not major components responsible for anti-genotoxic effects of tea extracts against nitroarenes. | the anti-genotoxic properties of tea leaf extracts were examined in a salmonella umu-test. seven non-fermented teas (green tea), one semi-fermented tea (oolong tea), two fermented teas (black tea and chinese pu er tea) and two other teas were examined for their anti-genotoxic abilities and for their catechins contents. this was to study the relationship between catechins contents and anti-genotoxic activity of various tea leaf extracts. all types of tea extracts showed more potent suppressive ef ... | 2001 | 11551482 |
| antioxidant activity of some foods containing phenolic compounds. | this study was designed to determine the total phenols (tp) and total antioxidant activity (taa) of some liquid and solid plant foods that are commonly consumed in turkey. total phenols were analysed according to the folin-ciocalteu method and antioxidant activities of these compounds in aqueous phase were assessed by measuring their direct abts.- radical scavenging abilities. total phenols varied from 68 to 4162 mg/l for liquid foods and from 735 to 3994 mg/kg for solid foods. taa of liquid and ... | 2001 | 11570016 |
| ntp toxicology and carcinogenesis studies of theophylline (cas no. 58-55-9) in f344/n rats and b6c3f1 mice (feed and gavage studies). | theophylline is an alkaloid found in tea (thea sinensis) and chocolate and is structurally related to caffeine and theobromine. theophylline is used as a pharmaceutical agent. it stimulates the heart and central nervous system, relaxes the smooth muscles of the bronchi and blood vessels, and causes diuresis. the drug is used mainly as a bronchodilator in obstructive airway diseases, such as bronchial asthma, and for myocardial stimulation. theophylline was nominated for toxicologic and carcinoge ... | 1998 | 12571677 |
| red wine and black tea polyphenols modulate the expression of cycloxygenase-2, inducible nitric oxide synthase and glutathione-related enzymes in azoxymethane-induced f344 rat colon tumors. | polyphenolic compounds extracted from red wine (we) and black tea (bt), 50 mg/(kg. d), inhibit the promotion phase of the colon carcinogenesis process induced by azoxymethane (aom) in rodents. to investigate possible mechanisms of this protective activity, we evaluated by rt-pcr the gene expression of cycloxygenase-2 (cox-2), inducible no synthase (inos), gamma-glutamylcysteine synthetase (gamma-gcs) and two isoforms of glutathione s-transferase (gst), gst-p and gst-m2, in 30 aom-induced tumors ... | 2002 | 12042461 |
| mechanisms of chronic disease causation by nutritional factors and tobacco products and their prevention by tea polyphenols. | the beverage tea, from the top leaves of the plant camellia sinensis is one of the most widely used beverages in the world, second only to water. black and green tea have mostly similar actions. the active components are polyphenols, mainly epigallocatechin gallate in green tea, and the tea leaf polyphenol oxidase mediated oxidation to oolong and black tea, yielding other polyphenols, theaflavin and thearubigins. there is 40-50 mg caffeine in a 160-ml cup of tea. the chemopreventive effects of t ... | 2002 | 12067577 |
| the mechanism underlying the protective effect of the thearubigin fraction of black tea (camellia sinensis) extract against the neuromuscular blocking action of botulinum neurotoxins. | the aim of the present study was to elucidate the mechanism of the protective effect of black tea extract, the thearubigin fraction, against the neuromuscular blocking action of botulinum neurotoxin types a, b, and e. the effects of thearubigin fraction extracted from a black tea infusion were examined on the neuromuscular blocking action of botulinum neurotoxin types a, b, and e in mouse phrenic nerve-diaphragm preparations and on the binding of these toxins to rat cerebrocortical synaptosomes. ... | 2002 | 12076314 |
| the effects of catechin on superoxide dismutase activity and its gene expression in pheochromocytoma cells. | overexpression of manganese superoxide dismutase (mnsod) cdna via plasmid transfection leads to growth inhibition in vitro and in vivo in various human cancers. polyphenolic compounds such as catechin isolated from tea bush camellia sinensis has been shown to have anticancer effect in vitro. this study evaluated the effect of catechin on the mnsod activity and mrna level of pheochromocytoma cells (pc-12). | 2002 | 12135191 |
| epigallocatechin-3-gallate inhibits interleukin-1beta-induced expression of nitric oxide synthase and production of nitric oxide in human chondrocytes: suppression of nuclear factor kappab activation by degradation of the inhibitor of nuclear factor kappab. | the proinflammatory cytokine interleukin-1beta (il-1beta) induces the production of high levels of nitric oxide (no) in human chondrocytes. green tea (camellia sinensis) polyphenols are potent antiinflammatory agents and have been shown to inhibit no production in tumor cell lines. in the present study, we examined the effect of epigallocatechin-3-gallate (egcg), a green tea polyphenol, on il-1beta-induced production of no in primary human osteoarthritis (oa) chondrocytes. | 2002 | 12209512 |
| comparative antimutagenic and anticlastogenic effects of green tea and black tea: a review. | tea is the most popular beverage next to water, consumed by over two-thirds of the world's population. it is processed in different ways in different parts of the world to give green, black or oolong tea. experimental studies have demonstrated the significant antimutagenic and anticlastogenic effects of both green and black tea and its polyphenols in multiple mutational assays. in the present review, we have attempted to evaluate and update the comparative antimutagenic and anticlastogenic effec ... | 2002 | 12220589 |
| sharing a bowl of tea. | soshitsu sen's keynote speech before a symposium on population and the environment is summarized unofficially by the editorial staff. the instability of human thinking is given as the cause for the present destruction of the environment. in a visit to the his majesty king of sweden, sen remarked that stabilizing human minds can be achieved within the tea ceremony through "serving tea heartily, receiving it with gratitude, and offering it to another." in this way, the spirit of concern for oth ... | 1993 | 12286476 |
| green tea (camellia sinensis) protects against selenite-induced oxidative stress in experimental cataractogenesis. | cataract is the leading cause of blindness worldwide. it is a multifactorial disease primarily associated with oxidative stress produced by free radicals. the protection offered by various antioxidants in cataract development is well established. polyphenolic compounds present in green tea (camellia sinensis) are reported to possess antioxidant property in various pathological conditions. the present study was undertaken to evaluate the anticataract potential of green tea leaf (gtl) extract in t ... | 2002 | 12297700 |
| antimutagenic effects of black tea (world blend) and its two active polyphenols theaflavins and thearubigins in salmonella assays. | almost two thirds of the world population consume tea everyday. tea is processed differently in different parts of the world to give green (20%), black (78%) or oolong tea (2%). the antimutagenic and anticarcinogenic activities of green tea were extensively investigated compared with those of black tea. considering the potent antimutagenic effects of green tea we recognized the need to evaluate the antimutagenic effects of black tea (world blend tea, southern tea co., marietta, ga) in salmonella ... | 2002 | 12410547 |
| an anticlastogenic in vivo micronucleus assay for tea. | common use of antimutagens and anticarcinogens in everyday life is an effective measure for preventing human cancer and genetic diseases. antioxidant properties of tea have vast potential as protective agents against diverse toxic effects. the present study was aimed to evaluate the role of aqueous clonal tea extracts (green tea, oolong tea and black tea) in modulating the genotoxic damage induced by cyclophosphamide (cp), a commonly used chemotherapeutic drug and a well-known mutagen and clasto ... | 2002 | 12674376 |
| anti-oxidative, anti-inflammatory and hepato-protective effects of ligustrum robustum. | aqueous extract of processed leaves of ligustrum robustum could dose-dependently scavenge superoxide radicals, inhibit lipid peroxidation, and prevent aaph-induced hemolysis of red blood cells. in comparison with green tea, oolong tea and black tea, processed leaves of l. robustum exhibited comparable antioxidant potency in scavenging superoxide radicals and in preventing red blood cell hemolysis. by activity-guided fractionation, a glycoside-rich fraction named fraction b2 was separated and dem ... | 2002 | 12413708 |
| inhibition of 12-o-tetradecanoylphorbol-13-acetate-induced inflammatory skin edema and ornithine decarboxylase activity by theaflavin-3,3'-digallate in mouse. | among black tea polyphenols, theaflavins were generally considered to be the most effective in cancer chemoprevention. in this study, we examined the inhibitory effects of black tea polyphenols, including theaflavin (tf-1), a mixture (tf-2) of theaflavin-3-gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate (tf-3), and the green tea polyphenol (-)-epigallocatechin-3-gallate (egcg) on 12-o-tetradecanoylphorbol-13-acetate (tpa)-induced edema and ornithine decarboxylase (odc) activity. top ... | 2002 | 12416263 |
| tea enhances insulin activity. | the most widely known health benefits of tea relate to the polyphenols as the principal active ingredients in protection against oxidative damage and in antibacterial, antiviral, anticarcinogenic, and antimutagenic activities, but polyphenols in tea may also increase insulin activity. the objective of this study was to determine the insulin-enhancing properties of tea and its components. tea, as normally consumed, was shown to increase insulin activity >15-fold in vitro in an epididymal fat cell ... | 2002 | 12428980 |