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PubMed1991

[Effects of green tea extract on the development of aflatoxin B1-induced precancerous enzyme-altered hepatocellular foci in rats].

Three kinds of extracts of green tea (decoction extract of green tea, water extract of green tea and ethanol extract of green tea) were tested for their effects on aflatoxin B1 (AFB1)-induced hepatocarcinogenesis in rats. The results revealed that all these three extracts of green tea possessed the remarkable inhibitory effects on the development of precancerous enzyme-altered hepatocellular foci. These results indicated that the main components of the green tea responsible for cancer prevention were all soluble in water and ethanol and thus providing an important clue for the search of the effective components in green tea for cancer prevention.

Aflatoxin B1↗
PubMed1990

[Inhibitory effects of a hot water extract from Japanese tea on the cell growth of mutans streptococci].

This study was undertaken to examine the effect of a hot water extract from Japanese tea on the cellular growth of mutans streptococci in vitro. The extract contained polyphenol compounds, mainly catechin derivatives. Few fluoride components were contained in the extract. Streptococcus mutans MT8148R (serotype c) and S. sobrinus MT6715 (serotype g) strains were used in the present study. The organisms (10-10(7) CFU/ml) were cultured in brain heart infusion (BHI) and tryptose phosphate (TP) broths containing the tea extract (0-8 mg/ml). After incubation for 24-48 hours the cell numbers in the cultures were determined. Furthermore, cell growth of these strains on BHI agar plates containing the extract (0-2 mg/ml) were examined. The results obtained were as follows: 1. The tea extract (2-8 mg/ml) in BHI broth inhibited remarkably the growth of S. mutans and S. sobrinus (inoculum size; 10(6) CFU/ml). No difference in susceptibility to the tea extract between S. mutans and S. sobrinus was noted. 2. The cell growth of both strains in TP broth was inhibited by the tea extract. However S. sobrinus was found to be more sensitive to the extract than S. mutans. 3. Growth of S. sobrinus cells on the BHI agar plate was suppressed by the tea extract more effectively than that of S. mutans. These results suggest that the tea extract would be useful as an anti-cariogenic agent.

Catechin↗
PubMed1990

The effect of Chinese tea on occurrence of esophageal tumor induced by N-nitrosomethylbenzylamine in rats.

Five groups of rats (40 rats per group) were given five different varieties of Chinese tea (1 g/50 ml) and another two groups of rats (a positive control and a negative control) were given tap water as drinking water. Except for the negative control group, all the animals were intubated with N-nitrosomethylbenzylamine (NMBzA, 5 mg/kg body wt/week). Half of the animals in each group were sacrificed after 6 weeks and the remaining animals at the end of 12 weeks. The incidences of esophageal mucosa lesions (16-59%) at the end of 6 weeks were significantly lower in the tea-treated rats than in the positive control group (100%). The incidences of esophageal tumor at the end of 12 weeks (42-67%) were also significantly lower in the tea-treated groups than in the positive control group (90%). The same phenomenon was found with respect to the size and number of tumors in each tumor-bearing animal. The relative anticarcinogenic effects of the five varieties of Chinese tea were different. The Fujian oolong tea and jasmine tea exhibited the strongest effects. The results suggest that Chinese tea can effectively inhibit the carcinogenesis caused by an N-nitroso compound.

Animals↗
PubMed1989

[The effect of Chinese teas on the occurrence of oesophageal tumor caused by N-nitrosomethylbenzylamine in rats].

Five groups of rats were given different varieties of Chinese tea as drinking water and on additional two groups of rats were given water with or without N-nitrosomethylbenzylamine (NMBzA) as controls. Except the control group, all the animals were intubated with NMBzA (5 mg.kg-1/wk) for 6 or 12 weeks. After 6 weeks, the incidence of oesophageal mucosa lesions was significantly lower in the tea-treated rats (16-59%) than the control group with NMBzA (100%). After 12 weeks, the incidence of oesophageal tumor was also significantly lower in the tea-treated groups (42-67%) than the control group with NMBzA (90%). Similar results were obtained in the tumor size and the number of tumors developed. The anti-carcinogenic effects of the 5 varieties of Chinese tea were also not the same the Fujian Oolong tea and Jasmine tea had the strongest effect. The results suggest that Chinese tea can inhibit the carcinogenesis caused by N-nitroso compound.

Animals↗
PubMedDate not supplied

[Benzo(a)pyrene content in tea].

Six samples of different kinds and sorts of native tea and 103 samples of tea beverage were tested for the benz(a)pyrene (BP) content. The results of the study showed that the carcinogen content in native tea varied from 2.4 micrograms/kg (in mixed tea No 36) to 3.84 micrograms/kg (in the Georgean tea, sort 1). The BP content in the tea beverage depended on the technology of its production. The carcinogen presence and its content increase in a violated technology of tea production may be an important factor in the genesis of esophagus carcinoma.

Benzo(a)pyrene↗
PubMed1994

[A study of green tea for a positive gastrointestinal MR imaging enhancing agent].

Green tea has been incidentally found to produce a high signal on T1-weighted MR images. This study was therefore designed to investigate what substance in the green tea produced this T1-shortening effect and whether a green tea solution could be used as a positive enhancing agent in MR studies. As a result of the chemical analysis and measurement of T1 relaxation times in various solutions originating from green tea, it was found that the T1-shortening effect was produced not only by free manganese, but also by a high molecular weight substance (molecular weight 1.2 x 10(4) or more) united with manganese. In clinical MR studies, the gastrointestinal tract was markedly enhanced after oral administration of a green tea solution. The pancreatic head was clearly delineated with visualization of both the gastric wall and descending portion of the duodenum. However, visualization of the jejunum and ileum was not improved, suggesting that the green tea solution was diluted by intestinal fluid in the small bowel. Since only a small amount of manganese (1500 ppm) united with a high molecular weight compound such as pectin was sufficient to produce excellent enhancement of the gastrointestinal tract, it would be better to develop a purely synthetic chemical compound, for example, one consisting of a polysaccharide and manganese, rather than to use a green tea solution as a gastrointestinal enhancing agent in MR studies.

Contrast Media↗
PubMed1993

Digoxin-like factors in herbal teas.

Forty-six commercially packaged teas and 78 teas prepared from purchased herbs were assayed for digoxin-like factors (DLF) by their crossreactivity with digoxin antibody (immuno-crossreactive DLF) and by their inhibition of ouabain binding to membrane Na,K-ATPase (NKA inhibitory DLF). Three packaged teas and 3 herbs gave NKA inhibitory DLF values > 30 micrograms digoxin equivalents/cup. Two packaged teas and 3 herbs gave immuno-crossreactive DLF values > .050 micrograms digoxin equivalent/cup. One herb, pleurisy root, had a crossreactive DLF value of 187 micrograms/cup and NKA inhibitory DLF equivalent to 3658 micrograms/cup. Plasma digoxin-like factors were measured after ingestion of the 3 commercially packaged herbal teas with highest values for NKA inhibitory DLF. After ingestion of each of the 3 teas, plasma NKA inhibitory DLF increase, in one case more than 100-fold. Two teas produced a measurable increase in plasma immuno-crossreactive DLF after ingestion. Some digoxin-like factors in human plasma may have a dietary source.

Beverages↗
PubMed1997

Tea consumption, lipid metabolism, and atherosclerosis.

The use of tea is derived from the Far East and was introduced into Europe, where in some countries tea soon became a favorite drink. Tea accounts for about 43% of all caffeine consumption. Total world caffeine consumption in 1981 was estimated to be approximately 120,000 tons, equivalent to 70 mg a day for each human. There is evidence from in vitro and animal studies, as well as from human investigations, that tea and its main constituents can prevent atherosclerosis to a certain extent. Supplementing tea as beverage instead of coffee might react beneficially with other antiatherosclerotic strategies. Investigations on the hypolipidemic and antiatherosclerotic action of tea, and therefore flavonoid intake, are still in their infancy and further fundamental data from controlled trials are needed to evaluate possible positive effects of tea consumption to prevent or treat atherosclerosis. Brief information on the biological potential of caffeine and flavonoids, as well as on their possible beneficial effects on the atherosclerotic process is documented in this review.

Animals↗
PubMed1997

[Effects of some Chinese herbal medicine and green tea antagonizing mutagenesis caused by cigarette tar].

Anti-mutagenic effects of some Chinese herbal medicine and green tea antagonizing cigarette tar was studied with unscheduled DNA synthesis (UDS) test in human peripheral lymphocytes in order to exploit the better use of Chinese herbal resources. Results showed that Scutellaria barbata, Hedyotis diffusa wildi, Xihuangwan, green tea and tea polyphenol all had anti-mutagenic effects, to some extent. And, 125 g/L of Scutellaria barbata, 125 g/L Hedyotis diffusa wildi, 325 g/L Xihuangwan, 78 g/L green tea and 25 g/L tea polyphenol could inhibit obviously the damage to DNA in lymphocytes caused by the total particle material (TPM) extracted from cigarette tar. If the Chinese herbal medicine and green tea were injected into cigarettes beforehand, extracted TPM (containing herbal medicine and green tea) also could protect DNA in lymphocytes from damage caused by cigarette tar, to even greater extent. This result is basically consistent with other anti-mutagenesis tests.

Adult↗
PubMed2026

Genome-wide identification and evolutionary analysis of the ERF-VII gene family in the tea plant (Camellia sinensis) and functional characterization of CsRAP2.2 in response to cold stress.

The ERF-VII gene family, a critical branch of the AP2/ERF superfamily, is central to plant stress adaptation. However, its evolutionary history and function in tea plant (Camellia sinensis) remain unclear. Here, we performed integrated evolutionary, genomic, and functional analyses of ERF-VII genes across 14 plant lineages and 20 tea plant cultivars. The phylogenetic analysis revealed that ERF-VII proteins originated after vascular plant divergence, coinciding with the emergence of the N-terminal MCGGA/I motif linked to the oxygen-dependent N-degron pathway. Gymnosperms retained few conserved members, whereas angiosperms exhibited lineage-specific expansion-extensive in monocots via whole-genome duplication, moderate in eudicots with functional diversification. Pan-genome analysis across 20 tea plant cultivars further revealed varietal differences in ERF-VII gene distribution. Transcriptome profiling via the Tea Plant Information Archive identified CsRAP2.2 as a cold-inducible ERF-VII member with sustained expression under low-temperature stress. Functional assays demonstrated that silencing CsRAP2.2 reduced cold tolerance, while overexpression in tea leaves and heterologous expression in Arabidopsis thaliana enhanced cold tolerance by maintaining photosystem II efficiency, reducing membrane lipid peroxidation, and improving antioxidant capacity. Weighted gene co-expression network analysis positioned CsRAP2.2 as a regulatory hub integrating cold, hormone, and oxygen-sensing pathways. These results clarify the evolutionary trajectory of ERF-VII genes and establish CsRAP2.2 as a core cold-tolerance regulator in tea plant. These findings may inform future breeding of cold-resilient tea cultivars.

Camellia sinensis↗
PubMed2006

Drinking of Salvia officinalis tea increases CCl(4)-induced hepatotoxicity in mice.

In a previous study, the drinking of a Salvia officinalis tea (prepared as an infusion) for 14 days improved liver antioxidant status in mice and rats where, among other factors, an enhancement of glutathione-S-transferase (GST) activity was observed. Taking in consideration these effects, in the present study the potential protective effects of sage tea drinking against a situation of hepatotoxicity due to free radical formation, such as that caused by carbon tetrachloride (CCl(4)), were evaluated in mice of both genders. Contrary to what was expected, sage tea drinking significantly increased the CCl(4)-induced liver injury, as seen by increased plasma transaminase levels and histology liver damage. In accordance with the previous study, sage tea drinking enhanced significantly GST activity. Additionally, glutathione peroxidase was also significantly increased by sage tea drinking. Since CCl(4) toxicity results from its bioactivation mainly by cytochrome P450 (CYP) 2E1, the expression level of this protein was measured by Western Blot. An increase in CYP 2E1 protein was observed which may explain, at least in part, the potentiation of CCl(4)-induced hepatotoxicity conferred by sage tea drinking. The CCl(4)-induced hepatotoxicity was higher in females than males. In conclusion, our results indicate that, although sage tea did not have toxic effects of its own, herb-drug interactions are possible and may affect the efficacy and safety of concurrent medical therapy with drugs that are metabolized by phase I enzymes.

Animals↗
PubMed1985

Comparison of the effects of internal TEA+ and Cs+ on potassium current in squid giant axons.

Internal tetraethylammonium (TEA) and cesium ions block outward potassium current in nerve membrane in a voltage-dependent manner. Blockade with Cs+ occurs virtually instantaneously after membrane depolarization, whereas blockade with TEA+ occurs after a delay. The latter result suggested to Armstrong (1966, J. Gen. Physiol., 50:279-293; 1969, J. Gen. Physiol., 54:553-575) that potassium channels must open before TEA+ blockade can occur, which is in contrast to Cs+ blockade, which appears to be independent of channel gating. The results in this study concerning the effect of TEA+ on inward (tail) current argue against the Armstrong model. Specifically, TEA+ (partially) blocks inward current without altering the tail current time constant. This result indicates that TEA+ can occupy its binding site within the channel whether or not the channel gates are open. This alternative hypothesis can describe both the steady-state and time-dependent components of TEA+ blockade.

Animals↗
PubMed1989

TEA prevents inactivation while blocking open K+ channels in human T lymphocytes.

The whole-cell recording mode of the patch-clamp technique was used to study the effect of external tetraethylammonium ([TEA+]o) on the inactivating, voltage-dependent K+ channels of human T lymphocytes. TEA+ reduced the peak amplitude and slowed the time course of the K+ current decay during a depolarizing pulse, resulting in a crossover of the current records in the presence and absence of TEA+. In solutions with different [TEA+]o both the peak K+ current amplitude, lKpeak, and the time constant of the decay of the K+ current, tau d, were reduced in a dose-dependent manner, both with apparent binding constants, KD, of 12 mM. The integral of K+ current during a prolonged depolarizing pulse was unaltered in solutions with different [TEA+]o. The concentration dependence of [TEA+]o on lKpeak, tau d, and the unchanged current integral can be explained with a kinetic scheme in which open channels blocked by TEA+ cannot inactivate.

Cell Line↗
PubMed2003

Effect of selenium on the yield and quality of green tea leaves harvested in early spring.

Foliar applications of a fertilizer of selenite or selenate were carried out to determine the influence of selenium on the yield and quality of green tea leaves harvested in early spring. Numbers of sprouts and the yield were significantly increased by the application of selenium. The sweetness and aroma of green tea leaves were also significantly enhanced, and bitterness was significantly decreased by the application of selenium. However, no significant differences were found in sweetness, bitterness, and aroma between tea leaves fertilized with selenite and selenate. Se concentration was significantly increased by selenium fertilization, and tea enriched by sodium selenate had a significantly higher selenium content than did tea enriched by sodium selenite. Total amino acid and vitamin C contents were significantly enhanced by the application of selenium. Tea polyphenol contents were significantly decreased by fertilization with selenium. The marked difference of tea polyphenols was also found between applications of selenite and selenate.

Camellia sinensis↗
PubMed2006

Effect of far-infrared irradiation on catechins and nitrite scavenging activity of green tea.

The processed green tea leaves were irradiated by far-infrared (FIR) at eight temperatures (80, 90, 100, 110, 120, 130, 140, and 150 degrees C) for 10 min. After FIR irradiation, green teas were prepared by soaking the leaves in boiling water, and the physicochemical characteristics of the green tea were determined. FIR irradiation at 90 degrees C increased total phenol contents of green tea from 244.7 to 368.5 mg/g and total flavanol contents from 122.0 to 178.7 mg/g, compared with non-irradiated control. FIR irradiation also significantly affected the amounts of epigallocatechin and epigallocatechin gallate. Nitrite scavenging activity also increased with increasing FIR irradiation until the temperature reached 110 degrees C. However, the overall color changes of green tea irradiated with FIR at 90 and 100 degrees C were negligible. These results indicate that the chemical quality of green tea is significantly affected by FIR irradiation temperature of the green tea leaves.

Caffeine↗
PubMed2006

Antifungal activities of major tea leaf volatile constituents toward Colletorichum camelliae Massea.

A crude glycosidic fraction was prepared from fresh tea leaves and treated with the crude tea enzyme, fractions of cis-3-hexenol, linalool oxide I (cis-furanoid), linalool oxide II (trans-furanoid), linalool, methyl salicylate, geraniol, benzyl alcohol, and 2-phenylethanol were monitored to be the major aglycone moieties by analyzing the released volatiles. The amount of the released aglycone moieties is 5.8 times higher than those in free form. For investigation of the functions of the glycosidically bound form aroma constituents in tea leaves, their antifungal activities were determined by antifungal assay. Geraniol, linalool, methyl salicylate, benzyl alcohol, and 2-phenylethanol exhibited significant antifungal activities toward Colletorichum camelliae Massea, although cis-3-hexenol and linalool oxides showed weaker activities by comparison. Among them, geraniol was shown to be the most potential antifungal substance with a MIC value of 440 microg/mL. The crude glycosidic fraction prepared from tea leaves also exhibited significant antifungal activities in a wide range of concentrations from 2 to 25 mg/mL in a PDA medium. It was deduced that the glycosidically bound volatiles are formed and stored in the intact tissue of tea leaf and hydrolyzed by the actions of both the endogenous and the exogenous glycosidases to release volatiles as antifungal substances when exposed to Colletorichum camelliae Massea. The results suggested that the higher content of the bound form geraniol in tea leaves of var. sinensis might be responsible for their stronger antipathogen properties toward tea leaf blight, as opposed to those of var. assamica.

Camellia sinensis↗
PubMed2004

Vitamin E analog alpha-TEA and celecoxib alone and together reduce human MDA-MB-435-FL-GFP breast cancer burden and metastasis in nude mice.

Alpha-TEA, a nonhydrolyzable ether analog of vitamin E (RRR-alpha-tocopherol), and celecoxib, a specific COX-2 inhibitor, were delivered separately or in combination to investigate their anticancer properties, using MDA-MB-435-FL-GFP human breast cancer xenografts in nude mice. Liposomal formulated alpha-TEA administered as an aerosol and celecoxib fed at 500 or 1250 mg/kg diet for 31 days separately or in combination significantly reduced tumor volume in comparison to control (p < 0.001 for all treatment groups). Of special note, the combinations of alpha-TEA + celecoxib (1250) inhibited tumor volume significantly better than either single treatment (p < 0.001 and p < 0.001). Average number of macroscopic lung metastases were significantly reduced in all treatment groups in comparison to control, with the exception of celecoxib (500). Mean numbers of microscopic lung and lymph node metastases in all treatment groups were significantly lower than control. Furthermore, the mean number of microscopic lung metastases in the alpha-TEA+celecoxib (1250) group were significantly lower than either separate treatment. Analyses of 5 microm tumor sections showed that all treatments, with the exception of celecoxib (500) alone, significantly enhanced apoptosis (TUNEL) and significantly decreased cell proliferation (Ki-67). alpha-TEA and alpha-TEA + celecoxib (1250) treatments significantly reduced blood vessel density (CD-31) in comparison to control. These data show promise for combination alpha-TEA + celecoxib chemotherapy for breast cancer.

Animals↗
PubMed2002

Protective effect of green tea against lipid peroxidation in the rat liver, blood serum and the brain.

This paper reports data on the effect of green tea on the lipid peroxidation products formation and parameters of antioxidative system of the liver, blood serum and central nervous tissue of healthy young rats drinking green tea for five weeks. The rats were permitted free access to solubilized extract of green tea. Bioactive ingredients of green tea extract caused in the liver an increase in the activity of glutathione peroxidase and glutathione reductase and in the content of reduced glutathione as well as marked decrease in lipid hydroperoxides (LOOH), 4-hydroksynonenal (4-HNE) and malondialdehyde (MDA). The concentration of vitamin A increased by about 40%. Minor changes in the measured parameters were observed in the blood serum. GSH content increased slightly, whereas the index of the total antioxidant status increased significantly. In contrast, the lipid peroxidation products, particularly MDA was significantly diminished. In the central nervous tissue the activity of superoxide dismutase and glutathione peroxidase decreased while the activity od glutathione reductase and catalase increased after drinking green tea. Moreover the level of LOOH, 4-HNE and MDA significantly decreased. The use of green tea extract appeared to be beneficial to rats in reducing lipid peroxidation products. These results support and substantiate traditional consumption of green tea as protection against lipid peroxidation in the liver, blood serum, and central nervous tissue.

Animals↗