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PubMed1999

Effects of green tea tannin on cisplatin-induced nephropathy in LLC-PK1 cells and rats.

A study was conducted to clarify whether green tea tannin ameliorated cisplatin-induced renal injury in terms of lactate dehydrogenase and malondialdehyde leakage from a renal epithelial cell line, swine-derived LLC-PK1 cells in culture. Green tea tannin was shown to suppress the cytotoxicity of cisplatin, the suppressive effect increasing with the dose of green tea tannin. The effect of cisplatin was then investigated in rats given green tea tannin for 40 days before cisplatin administration and in control rats given no green tea tannin. In control rats, blood, urinary and renal parameters and the activities of antioxidative enzymes in renal tissue deviated from the normal range, indicating dysfunction of the kidneys. In contrast, rats given green tea tannin showed decreased blood levels of urea nitrogen and creatinine, and decreased urinary levels of protein and glucose, reflecting less damage to the kidney. In this group, the activity of catalase in the renal tissue was increased, while the level of malondialdehyde was decreased, suggesting the involvement of radicals in the normalizing of kidney function. Based on the evidence available it appeared that green tea tannin eliminated oxidative stress and was beneficial to renal function.

Animals↗
PubMed2006

Effect of green tea consumption on endothelial function and circulating endothelial progenitor cells in chronic smokers.

BACKGROUND: The present study was designed to investigate the effect and relationship of endothelial function and endothelial progenitor cells (EPCs) by green tea consumption in chronic smokers. The numbers of circulating EPCs have an inverse correlation with chronic smoking and endothelial dysfunction. Green tea catechin improved endothelial dysfunction in chronic smokers. METHOD AND RESULTS: In 20 young healthy smokers, endothelial functions, defined by flow-mediated endothelium dependent vasodilation (FMD) of the brachial artery via ultrasound as well as the number of EPCs isolated from peripheral blood, were determined at baseline and at 2 weeks after green tea consumption (8 g/day). Circulating EPCs were quantified by flow cytometry as CD45lowCD34+KDR2+ cells and by acyl-low-density lipoprotein and fluorescein isotiocyanate-lectin double positive cells after culture for 7 days. Clinical characteristics and laboratory findings were not significantly different between the baseline and at 2 weeks after green tea intake. EPC levels were inversely correlated with the number of cigarettes smoked. Circulating EPCs by flow cytometry (78.6+/-72.6 vs 156.1+/-135.8 /ml, p<0.001) and cultured EPCs (118.2+/-35.7 vs 169.31+/-58.3/10 field, p<0.001) increased rapidly at 2 weeks after green tea consumption. FMD was significantly improved after 2 weeks (7.2+/-2.8 vs 9.3+/-2.4, p<0.001). The FMD correlated with EPC counts (r=0.67, p=0.003) before treatment and after 2 weeks (r=0.60, p=0.013). CONCLUSIONS: A short-term administration of green tea consumption induces a rapid improvement of EPC levels and FMD. Green tea consumption may be effective to prevent future cardiovascular events in chronic smokers.

Adult↗
PubMed1998

Effects of tea infusions of various varieties or different manufacturing types on inhibition of mouse mast cell activation.

We investigated effects of various tea infusions on mast cell activation using mouse mast cells. Among various tea extracts, infusions from cultivar 'Benihomare' and Taiwan lineage strongly inhibited histamine release after Fc epsilon RI cross-linking. Among three types of tea (from cultivar 'Benihomare'), extract from oolong tea or black tea inhibited histamine release more strongly than green tea extract. Furthermore, 'Benihomare' oolong tea extract suppressed tyrosine phosphorylation of cellular proteins after Fc epsilon RI cross-linking, but polyvinyl polypyrrolidone treatment of the extract to remove phenolic compounds, weakened the suppressive effect.

Animals↗
PubMed2001

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 contribute to cancer chemopreventive effects of tea.

Apoptosis↗
PubMed2005

Dietary gallate esters of tea catechins reduce deposition of visceral fat, hepatic triacylglycerol, and activities of hepatic enzymes related to fatty acid synthesis in rats.

Tea catechins, rich in (-)-epigallocatechin gallate and (-)-epicatechin gallate, or heat-treated tea catechins in which about 50% of the (-)-epigallocatechin gallate and (-)-epicatechin gallate in tea catechins was epimerized to (-)-gallocatechin gallate and (-)-catechin gallate, were fed to rats at 1% level for 23 d. Visceral fat deposition and the concentration of hepatic triacylglycerol were significantly lower in the tea catechin and heat-treated tea catechin groups than in the control group. The activities of fatty acid synthase and the malic enzyme in the liver cytosol were significantly lower in the two catechin groups than in the control group. In contrast, the activities of carnitine palmitoyltransferase and acyl-CoA oxidase in the liver homogenate were not significantly different among the three groups. These results suggest that the reduction in activities of enzymes related to hepatic fatty acid synthesis by the feeding of tea catechins or heat-treated tea catechins can cause reductions of hepatic triacylglycerol and possibly of visceral fat deposition.

Adipose Tissue↗
PubMed1994

Epigallocatechin gallate. The major causative agent of green tea-induced asthma.

We describe three patients who worked in green tea factories and developed asthmatic and nasal symptoms after exposure to green tea dust. To clarify what component(s) of green tea leaves might be responsible for causing asthma, we prepared catechins, the major components of green tea leaves. Epigallocatechin gallate (EGCg; MW: 458 daltons), a major catechin, was purified by high-performance liquid chromatography. Subjects included three patients with green tea-induced asthma, five asthmatics with no previous exposure to tea dust, and five healthy controls. It was found that all three patients exhibited an immediate skin and bronchial response to EGCg. Prausnitz-Küstner test with EGCg was also positive. However, none of the asthmatic and healthy controls showed a positive reaction. These results indicate that EGCg is a causative agent of green tea-induced asthma and suggest that an IgE-mediated response is, at least in part, responsible for causing this type of occupational asthma.

Asthma↗
PubMed2002

Anti-invasive effects of green tea polyphenol epigallocatechin-3-gallate (EGCG), a natural inhibitor of metallo and serine proteases.

Several reports have attributed to green tea chemopreventive and therapeutic properties. Epidemiological studies have linked the regular use of green tea to a reduced incidence of breast and colon carcinomas. Tea contains several antioxidants, including polyphenols of the catechin (green tea) and theaflavin (black tea) groups. Green tea derivatives have been shown to act in vitro and in vivo as anti-inflammatory, anti-viral and anti-tumor drugs. Despite the extensive body of data only few studies have investigated the molecular mechanisms underlying these effects. In this brief review we focus on the inhibitory activity of catechins derived from green tea toward proteases involved in tumor invasion.

Catechin↗
PubMed2000

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 CCl4 (1 ml/kg, i.p.) and sacrificed two hours later. Rats in the other control group were administered olive oil in a similar fashion. Lipid peroxide levels in liver and plasma, glutathione (GSH) levels in liver and alanine transaminase (ALT) and aspartate transaminase (AST) activities in plasma were measured. Rats in the black tea group were found to have significantly decreased liver lipid peroxide levels, and ALT and AST activities compared with the rats in the CCl4-treated control group. In addition, liver glutathione levels were decreased in the black tea group. These data suggest that black tea attenuates CCl4-induced hepatic injury.

Alanine Transaminase↗
PubMed2000

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 and the black tea group. They were sacrificed after 2 hours. Rats in the other control group were administered olive oil in a similar fashion. Measurements were made of lipid peroxide levels in liver and plasma, glutathione levels in liver, and alanine transaminase (ALT) and aspartate transaminase (AST) activities in plasma. Liver lipid peroxide levels, plasma ALT and AST activities were significantly decreased in the black tea group compared with the CCl4-treated control group, while plasma lipid peroxide levels were not. These results are parallel to those previously found with Wistar male rats. Glutathione levels, however, were not significantly affected, in contrast to the data relating to male rats, either after CCl4 or black tea treatments. The results of our study add to the findings that black tea attenuates CCl4-induced hepatic injury but also indicates the susceptibility of glutathione levels to endocrinological effects.

Alanine Transaminase↗
PubMed2002

Protective effect of Boldo and tea infusions on the visible light-mediated pro-oxidant effects of vitamin B2, riboflavin.

The effect of Boldo and black tea infusions on the pro-oxidant effects of vitamin B2, riboflavin (RF), when exposed to the action of visible light was studied. The amounts of antioxidants present in Boldo and tea infusions were evaluated by a procedure based on the bleaching of preformed 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cations and were expressed as 6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic acid equivalent concentrations. The quenching rate constants of singlet oxygen (1O2; [kq]Boldo = 6.0 x 10(7) M(-1) s(-1) and [kq]Tea = 3.2 x 10(7) M(-1) s(-1)) and triplet RF (3RF; [3RFkq]Boldo = 10 x 10(8) M(-1) s(-1) and [3RFkq]TEA = 3.2 x 10(8) M(-1) s(-1)) with Boldo and tea were determined by flash photolysis. These data allow a quantitative interpretation of the results obtained. Our data suggest that most of the oxygen consumption observed in the photolysis of RF in the presence of tea and Boldo infusions is caused by 1O2 reactions. The oxygen consumption quantum yield is considerably smaller than the fraction of RF triplets trapped by the additives (AH) present in the infusion, indicating that their interaction with 3RF does not lead to chemical reactions or that the AH*+ radical ions initially formed participate in secondary processes that do not consume oxygen. Boldo and tea infusions have a significant protective effect when a system containing RF and tryptophan (Trp) is exposed to visible light, not only by quenching the 1O2 and interfering with the Type-I mechanism but also by repairing the damage to Trp molecules associated with the latter mechanism.

Chromans↗
PubMed2005

Black tea protects thymocytes in tumor-bearing animals by differential regulation of intracellular ROS in tumor cells and thymocytes.

The accumulated in vitro evidence indicates that many tumors induce T-cell apoptosis as a mechanism of inhibiting antitumor activity. This downregulation of cell-mediated immune functions occurring at the late stages of the disease may be causally related to the thymic involution, because the thymus is the major site of T-cell maturation, extensive proliferation, and differentiation. Our results showed that in Erhlich's ascites carcinoma cell (EAC)-bearing mice, the number of EAC was inversely proportional to the thymocyte count in the host's thymus, which is the primary immune organ. Further studies indicated the presence of tumor-induced thymocyte apoptosis in EAC bearers. Black tea prolonged the survival of the tumor bearer by successfully restricting tumor progression as well as protecting the thymus from tumor insult. In fact, black tea inhibited thymic apoptosis while inducing programmed cell death of EAC. Interestingly, the tea regulated the oxidant status differentially in EAC and thymocytes--i.e., it reduced the EAC-induced reactive oxygen species (ROS) generation in the thymus while activating the same in the EAC. A similar effect of black tea was obtained when thymocytes were cultured in the presence of cell-free ascitic fluid, thereby indicating that black tea could directly reduce oxidative stress, an activity independent of its tumoricidal property. As a result, the maturation block in thymocyte subpopulations in tumor bearers was ameliorated significantly in black tea-treated animals. Our results demonstrate that black tea protects thymocytes in the tumor bearer by regulating the intracellular ROS in tumor cells and thymocytes differentially, thereby strengthening its candidacy in future anticancer therapeutic regimens.

Animals↗
PubMed2005

Amelioration of sodium arsenite-induced clastogenicity by tea extracts in Chinese hamster v79 cells.

Since the early 1980s, an alarming problem of groundwater arsenic (As) contamination has devastated many districts of West Bengal in India. People drinking As-contaminated water have been suffering severe health problems such as hyperkeratosis, blackfoot disease, neuropathy, and cancer of various sites. DNA damage and genetic instability induced by the inorganic arsenicals present in water are thought to be prerequisites for the initiation of carcinogenesis. Many natural polyphenols, which are consumed through our daily diet, possess excellent cancer chemopreventive properties. Tea, a popular beverage worldwide and rich in polyphenols, has exhibited many health benefits. The present study was conducted to examine the anticlastogenic action of tea extracts (both green and black) against the As-induced chromosomal aberrations. We also evaluated the role of tea in inducing antioxidant enzymes such as superoxide dismutase and catalase to provide protection against the oxidative stress induced by As. Our results demonstrated that tea extracts, particularly Darjeeling tea extract, are effective in counteracting the clastogenicity (chromatid breaks, in particular) of the most potent form of As, sodium arsenite. The antioxidant function of tea in reducing clastogenicity may be partly due to the induction of phase II detoxification enymes, such as superoxide dismutase and catalase. Our results suggest that the use of tea may be an effective approach in combating the health crisis generated by As.

Animals↗
PubMed2006

Favorable effects of tea on reducing the cognitive deficits and brain morphological changes in senescence-accelerated mice.

The present study was carried out to explore the effects of oolong and green teas on improving the memory deficits and brain pathological changes in senescence accelerated-prone mice P8 (SAMP8). Six-month-old mice were supplied with oolong tea, green tea or water as the sole drinking fluid for 16 wk. The memory ability of mice was evaluated by passive and active avoidance tests, while the extent of the brain degeneration was measured by the spongiosis grades and the lipofuscin percentage in the hippocampus. The total grading score and serum biochemical levels were also measured. The results indicated that the mice supplemented with the oolong and green tea drinks reversed the cognitive impairment, lessened the spongy degeneration and lipofuscin, and increased the serum Trolox equivalent antioxidant capacity more than the control group. The total grading score of the oolong tea group was lower than that of the control group in male mice, whereas it did not differ among female groups. No differentiations in the concentrations of total cholesterol. triglyceride, glucose, iron or hemoglobin were observed among three drink groups. In conclusion, oolong and green teas could reduce the deteriorations of cognitive ability, brain degenerative changes and aging process in SAMP8, probably through the potent antioxidative activity of the tea.

Aging↗
PubMed2005

Pu-erh tea supplementation suppresses fatty acid synthase expression in the rat liver through downregulating Akt and JNK signalings as demonstrated in human hepatoma HepG2 cells.

Fatty acid synthase (FAS) is a key enzyme of lipogenesis. Overexpression of FAS is dominant in cancer cells and proliferative tissues. The expression of FAS in the livers of rats fed pu-erh tea leaves was significantly suppressed. The gains in body weight, levels of triacylglycerol, and total cholesterol were also suppressed in the tea-treated rats. FAS expression in hepatoma HepG2 cells was suppressed by the extracts of pu-erh tea at both the protein and mRNA levels. FAS expression in HepG2 cells was strongly inhibited by PI3K inhibitor LY294002 and JNK inhibitor II and slightly inhibited by p38 inhibitor SB203580 and MEK inhibitor PD98059, separately. Based on these findings, we suggest that the suppression of FAS in the livers of rats fed pu-erh tea leaves may occur through downregulation of the PI3K/AKt and JNK signaling pathways. The major components of tea that have been demonstrated to be responsible for the antiobesity and hypolipidemic effects are catechins, caffeine, and theanine. The compositions of catechins, caffeine, and theanine varied dramatically in pu-erh, black, oolong, and green teas. The active principles and molecular mechanisms that exerted these biological effects in pu-erh tea deserve future exploration.

Animals↗
PubMed2004

Antibacterial effect of water-soluble tea extracts on foodborne pathogens in laboratory medium and in a food model.

The microbial inhibition of foodborne pathogens was determined in brain heart infusion broth with 10% (wt/vol) water-soluble extracts of green, jasmine, black, dungglre, and oolong tea against Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Listeria monocytogenes, and Staphylococcus aureus. The mixed culture (approximately 6.0 log CFU/ml), which was composed of the four pathogens, was inoculated into brain heart infusion broth with and without tea extracts. After incubation at 35 degrees C for 0, 1, 3, and 5 days, proper dilution of each sample was spiral plated on each selective agar. Viable cell counts were performed after incubation at 35 degrees C for 24 to 36 h. Green, jasmine, and black tea exhibited an approximately 5.0 log suppression of S. aureus compared with the control from days 1 to 5. Green and jasmine tea also suppressed the growth of L. monocytogenes by approximately 3.0 log CFU/ml on day 5. In contrast, no tea extracts inactivated E. coli O157:H7 and Salmonella Enteritidis. Based on the result in liquid medium, green and jasmine teas of 0.1% (vol/wt) were individually evaluated for their antimicrobial activity against L. monocytogenes and S. aureus in a food model (ground beef) stored at 7 degrees C for 0, 1, 3, 5, and 7 days. Viable cell counts of total bacteria, L. monocytogenes, and S. aureus in ground beef were not significantly different among green and jasmine tea and the control.

Anti-Bacterial Agents↗
PubMed2001

Identification and antioxidant activity of several pigments from the residual green tea (Camellia sinensis) after hot water extraction.

Antioxidant activity of green tea extract or tea-derived polyphenols has been extensively studied. However, antioxidant activity in the non-polyphenolic fraction of green tea has been poorly analyzed. In the present study, we analyzed the antioxidant activity of the non-polyphenolic fraction of the residual green tea (Camellia sinensis) after hot water extraction using the aluminum chloride method. The non-polyphenolic fraction of residual green tea caused a significant suppression against hydroperoxide generation from oxidized linoleic acid in a dose-dependent manner. When the concentrate of the non-polyphenolic fraction was applied to a silica gel TLC plate and developed, six color spots were observed, which were considered to be chlorophylls a and b, pheophytins a and b, carotenoids, such as beta-carotene and lutein according to their specific colors, Rf values of silica gel TLC and spectrophotometric properties. Among these pigments, pheophytins a and b showed relatively abundant amounts, and the second major group of the pigment was chlorophylls a and b, and carotenoids such as beta-carotene and lutein indicated lower concentrations. Although all these pigments exhibited significant antioxidant activities, the ranks of suppressive activity against hydroperoxide generation were chlorophyll a > lutein > pheophytin a > chlorophyll b > beta-carotene > pheophytin b. These results suggest that the non-polyphenolic fraction of residual green tea has a potent suppressive activity against hydroperoxide generation from oxidized linoleic acid, which is derived from the antioxidant activities of chlorophylls a and b, pheophytins a and b, beta-carotene and lutein. This finding also implies that the combined intake of polyphenols in water-soluble fraction and antioxidative pigments in the non-polyphenolic fraction of green tea will be more efficient to prevent life style-related chronic diseases.

Acetone↗
PubMed1997

[Induction of apoptosis by tea polyphenols in MGC cells].

In order to search for tumor cells apoptosis inducer, the apoptosis effects and mechanism of tea polyphenols were studied. Tea polyphenols is an active compounds purified from tea. The apoptosis effects of tea polyphenols were observed on the human gastric carcinoma cells (MGC) by MTT reduction test, DNA agarose gel electrophoresis and transmission electron microscopy (TEM) technique. Having been treated by tea polyphenols in 125 micrograms.ml-1 for 24 h, DNA extracted from MGC cells showed a typical internuclesosomal DNA degradation, i.e., DNA ladder and apoptotic vehicles were observed under TEM. The effects of tea polyphenols were shown to parallel with its cytotoxic activity in MGC cells. These results suggest that the mechanism of antitumor action of tea polyphenols is related to its apoptosis inducing activity.

Adenocarcinoma↗
PubMed1998

[Chemoprotection by green tea against the formation of food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP)-DNA adducts in rats].

OBJECTIVE: The food-borne mutagen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) induces colon and mammary gland tumors in rats and has been implicated in the etiology of human cancer, particularly colorectal cancer. This study was conducted to examine the potential chemopreventive effect of Chinese green tea against PhIP-DNA adduct formation in rats and its possible mechanisms. METHODS: Sprague-Dawley rats were maintained on freshly prepared aqueous extract of Chinese green tea (3%) or tap water as the sole source of drinking fluid for 10 days prior to administration with a single dose of PhIP (10 mg/kg body wt) by oral gavage. Rats were sacrificed at 20 h after PhIP treatment and PhIP-DNA adducts in the colon, heart, lung, and liver were analyzed using 32P-postlabeling technique. The activity of cytosolic glutathione S-transferases (GSTs) in the liver, lung and colon mucosa was also determined using CDNB as substrate. RESULTS: The levels of PhIP-DNA adducts in the four tissues of rats treated with PhIP alone were highest in the colon (53 +/- 9 adducts/10(8) nucleotides), followed by heart (41 +/- 14 adducts/10(8) nucleotides) and lung (22 +/- 5 adducts/10(8) nucleotides), but much lower in the liver (5 +/- 3 adducts/10(8) nucleotides). Rats pre-treated with green tea had significantly reduced levels of PhIP-DNA adducts, with the inhibition rates being 59%-80%, respectively. While the organ distribution profile of the adducts was not altered by tea treatment as compared with controls given PhIP alone. The GST activity towards CDNB in hepatic, colonic and lung cytosols appear not to be modified by drinking green tea. CONCLUSION: These results support a protective role for green tea against PhIP-initiated carcinogenesis in rats and suggest that consumption of green tea may have significant impact in chemoprevontion against human cancer presumably related to PhIP and other heterocyclie amines.

Animals↗