Green tea extract affects porcine ovarian cell apoptosis

Green tea is a commonly used beverage and green tea extract is a common dietary herbal supplement manufactured into different over-the-counter products. The aim of this in vitro study was to examine the steroid hormone secretion (progesterone and 17-β estradiol), proliferation and apoptosis of porcine ovarian granulosa cells after addition of green tea extract. Granulosa cells were incubated with green tea extract at five doses (0.1, 1, 10, 100 and 200?μg/ml) and the release of hormones by granulosa cells was assessed by EIA after 24?h exposure. The presence of proliferation and apoptotic markers was assessed by immunocytochemistry. Secretion of steroid hormones was not affected by green tea extract at all the doses in comparison to control. Also, markers of proliferation (PCNA and cyclin B1) were not affected by green tea extract. However, the highest dose (200?μg/ml) of green tea extract used in this study increased the accumulation of apoptotic markers caspase-3 and p53 in granulosa cells. In conclusion, our results indicate the impact of green tea extract at the highest dose used in this study on ovarian apoptosis through pathway that includes activation of caspase-3 and p53. Potential stimulation of these intracellular regulators could induce the process of apoptosis in ovarian cells.     

Prevention of hepatic ischemia-reperfusion injury by green tea extract

These experiments were designed to determine whether green tea extract (GTE), which contains polyphenolic free radical scavengers, prevents ischemia-reperfusion injury to the liver. Rats were fed a powdered diet containing 0-0.3% GTE starting 5 days before hepatic warm ischemia and reperfusion. Free radicals in bile were trapped with the spin-trapping reagent alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) and measured using electron spin resonance spectroscopy. Hepatic ischemia-reperfusion increased transaminase release and caused pathological changes including focal necrosis and hepatic leukocyte infiltration in the liver. Transaminase release was diminished by over 85% and pathological changes were almost totally blocked by 0.1% dietary GTE. Ischemia-reperfusion increased 4-POBN/radical adducts in bile nearly twofold, an effect largely blocked by GTE. Epicatechin, one of the major green tea polyphenols, gave similar protection as GTE. In addition, hepatic ischemia-reperfusion activated NF-kappa B and increased TNF-alpha mRNA and protein expression. These effects were all blocked by GTE. Taken together, these results demonstrate that GTE scavenges free radicals in the liver after ischemiareoxygenation, thus preventing formation of toxic cytokines. Therefore, GTE could prove to be effective in decreasing hepatic injury in disease states where ischemia-reperfusion occurs.     

Anti-inflammatory activity of tea (Camellia sinensis) root extract

Pharmacological studies were carried out with methanol-water (1:1) extract of dried tea (Camellia sinensis) root extract (TRE). TRE was found to possess anti-inflammatory, analgesic and antipyretic activities at 1/10th of its LD50 dose of 100 mg/kg i.p. It was found that TRE inhibited the arachidonic acid-induced paw oedema in rats which indicated that TRE produced the anti-inflammatory activity by inhibiting both the cyclooxygenase and lypooxygenase pathways of arachidonic acid metabolism. TRE also enhanced peritoneal cell count and the number of macrophages in normal mice. It is plausible that the saponins present in TRE may be responsible for these activities of TRE.     

Metabolic response to green tea extract during rest and moderate-intensity exercise

BackgroundGreen tea catechins have been hypothesized to increase energy expenditure and fat oxidation by inhibiting catechol-O-methyltransferase (COMT) and thus promoting more sustained adrenergic stimulation. Metabolomics may help to clarify the mechanisms underlying their putative physiological effects.ObjectiveThe study investigated the effects of 7-day ingestion of green tea extract (GTE) on the plasma metabolite profile at rest and during exercise.MethodsIn a placebo-controlled, double-blind, randomized, parallel study, 27 healthy physically active males consumed either GTE (n=13, 1200 mg catechins, 240 mg caffeine/day) or placebo (n=14, PLA) drinks for 7 days. After consuming a final drink (day 8), they rested for 2 h and then completed 60 min of moderate-intensity cycling exercise (56%±4% VO₂max). Blood samples were collected before and during exercise. Plasma was analyzed using untargeted four-phase metabolite profiling and targeted profiling of catecholamines.ResultsUsing the metabolomic approach, we observed that GTE did not enhance adrenergic stimulation (adrenaline and noradrenaline) during rest or exercise. At rest, GTE led to changes in metabolite concentrations related to fat metabolism (3-β-hydroxybutyrate), lipolysis (glycerol) and tricarboxylic acid cycle (TCA) cycle intermediates (citrate) when compared to PLA. GTE during exercise caused reductions in 3-β-hydroxybutyrate concentrations as well as increases in pyruvate, lactate and alanine concentrations when compared to PLA.ConclusionsGTE supplementation resulted in marked metabolic differences during rest and exercise. Yet these metabolic differences were not related to the adrenergic system, which questions the in vivo relevance of the COMT inhibition mechanism of action for GTE.     

Green tea extract protects against early alcohol-induced liver injury in rats

Oxidants have been shown to be involved in alcohol-induced liver injury. This study was designed to test the hypothesis that the antioxidant polyphenolic extract of green tea, comprised predominantly of epigallocatechin gallate, protects against early alcohol-induced liver injury in rats. Male Wistar rats were fed high-fat liquid diets with or without ethanol (10-14 g kg(-1) day(-1)) and green tea (300 mg kg(-1) day(-1)) continuously for 4 weeks using an intragastric enteral feeding protocol. Mean body weight gains (approximately 4 g/day) were not significantly different between treatment groups, and green tea extract did not the affect average concentration or the cycling of urine ethanol concentrations (0-550 mg dl(-1) day(-1)). After 4 weeks, serum ALT levels were increased significantly about 4-fold over control values (35+/-3 IU/l) by enteral ethanol (114+/-18); inclusion of green tea extract in the diet significantly blunted this increase (65+/-10). Enteral ethanol also caused severe fatty accumulation, mild inflammation, and necrosis in the liver. While not affecting fat accumulation or inflammation, green tea extract significantly blunted increases in necrosis caused by ethanol. Furthermore, ethanol significantly increased the accumulation of protein adducts of 4-hydroxynonenal, a product of lipid peroxidation and an index of oxidative stress; green tea extract blocked this effect almost completely. TNFalpha protein levels were increased in liver by alcohol; this phenomenon was also blunted by green tea extract. These results indicate that simple dietary antioxidants, such as those found in green tea, prevent early alcohol-induced liver injury, most likely by preventing oxidative stress.     

Black tea extract supplementation decreases oxidative damage in Jurkat T cells

The purpose of this study was to investigate the protective effect of black tea (BT) extract against induced oxidative damage in Jurkat T-cell line. Cells supplemented with 10 or 25 mg/L BT were subjected to oxidation with ferrous ions. Malondialdehyde (MDA) production as marker of lipid peroxidation, DNA single strand breaks as marker of DNA damage, and modification of the antioxidant enzyme activity, glutathione peroxidase (GPX) were measured. Results show the efficacy of BT polyphenols to decrease DNA oxidative damage and to affect GPX activity (P<0.05), while no effect was shown on MDA production. The succeeding investigation of the activity of caffeine and epigallocatechin gallate demonstrated their antioxidant potential with respect to the cellular markers evaluated. In conclusion, this study supports the protective effect of BT against ferrous ions induced oxidative damage to DNA and the ability of BT to affect the enzyme antioxidant system of Jurkat cells.     

Green tea polyphenol extract attenuates colon injury induced by experimental colitis

Inflammatory bowel disease (IBD) is characterised by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. The aim of the present study was to examine the effects of green tea extract in rats subjected to experimental colitis induced by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). At 4 days after DNBS administration the rats were sacrificed. Treatment with green tea extract significantly attenuated diarrhoea and loss of body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture, significant reduction of colonic myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-alpha) production. Green tea extract also reduced the appearance of nitrotyrosine immunoreactivity in the colon and reduced the up-regulation of ICAM-1.     

Antifungal and fungicidal activities of tea extract and catechin against Trichophyton

We examined tea extract, (-) epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) for their antifungal and fungicidal activities against Trichophyton mentagrophytes, T. rubrum, Candida albicans and Cryptococcus neoformans. Tea extract (2.5%) inhibited completely the growth of both T. mentagrophytes and T. rubrum. EGCg at 2.5 mg/ml failed to inhibit their growth, whereas TF3 at 0.5 mg/ml inhibited the growth. EGCg (1mg/ml) showed no fungicidal activity against Trichophyton. TF3 (1mg/ml) killed Trichophyton by a long time contact (72-96 hrs). Tea extract showed a fungicidal activity against Trichophyton in a dose- and contact time-dependent manner. It did not inhibit the growth of C. albicans, but at a high concentration, inhibited slightly the growth of C. neoformans. It had no fungicidal activity against C. albicans or C. neoformans.     

Suppression of Helicobacter pylori-induced gastritis by green tea extract in Mongolian gerbils

Since urease of Helicobacter pylori is essential for its colonization, we focused attention on foodstuffs which inhibit the activity of this enzyme. Among plant-derived 77 foodstuff samples tested, some tea and rosemary extracts were found to clearly inhibit H. pylori urease in vitro. In particular, green tea extract (GTE) showed the strongest inhibition of H. pylori urease, with an IC(50) value of 13 microg/ml. Active principles were identified to be catechins, the hydroxyl group of 5(')-position appearing important for urease inhibition. Furthermore, when H. pylori-inoculated Mongolian gerbils were given GTE in drinking water at the concentrations of 500, 1000, and 2000 ppm for 6 weeks, gastritis and the prevalence of H. pylori-infected animals were suppressed in a dose-dependent manner. Since the acquisition by H. pylori of resistance to antibiotics has become a serious problem, tea and tea catechins may be very safe resources to control H. pylori-associated gastroduodenal diseases.     

Black tea extract suppresses transformation of aryl hydrocarbon receptor induced by dioxin

Dioxins cause various adverse effects through binding to an aryl hydrocarbon receptor (AhR) and transformation of the receptor. In this study, we investigated whether black tea extract suppresses AhR transformation. Dried black tea leaves were extracted with 75% ethanol, and the extract was pretreated to the rat liver cytosol fraction 10 min prior to addition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Transformed AhR was detected by electrophoretic gel mobility shift assay. Black tea extract suppressed AhR transformation in a dose-dependent manner, and the IC50 value against 1 nM TCDD-induced AhR transformation was 8.9 microg/ml. The result suggests that intake of black tea has a potential to suppress the AhR transformation, leading protection from dioxin toxicity.     

Synthesis and purification of kaempferol by enzymatic hydrolysis of tea seed extract

We have made an in-depth study on elucidating selective hydrolysis reaction by enzyme on two kinds of flavonol triglycosides, camelliaside A (CamA) and camelliaside B (CamB). In this paper, we employ five kinds of commercial enzyme complexes and report their effect on the hydrolysis reaction of CamA and CamB. Ultraflo, Celluclast and Shearzyme selectively hydrolyze the xylosyl moiety of CamB, producing primarily kaempferol diglycoside, while Dextrozyme yielding monoglycoside. Whereas, Viscozyme transform CamA and CamB into kaempferol (KR) by non-specific hydrolysis. We recover KR with 95.4% purity from a scale-up reaction with Viscozyme followed by recrystallization of crude KR.     

Protection of renal function by green tea extract during Plasmodium berghei infection

Impairment of renal function from oxidative stress during malaria infection is one of the leading causes of death in endemic areas. Since blood urea nitrogen and creatinine levels in plasma can be used as markers for monitoring renal damage, this study investigated the effect of green tea extract on reduction of blood urea nitrogen and creatinine levels during malaria infection using Plasmodium berghei ANKA infected mice as in vivo model. For in vivo testing, ICR mice were infected with 1 × 10⁷ parasitized erythrocytes and green tea extract was subsequently administered orally twice a day for 10 consecutive days. Parasitemia was estimated by standard microscopy, and blood urea nitrogen and creatinine levels in plasma were also measured. It was found that parasitemia kept increasing until animal death, and is strongly correlated with high blood urea nitrogen and creatinine. The highest levels of blood urea nitrogen and creatinine in plasma were found on day 10 after infection. However, blood urea nitrogen and creatinine levels in plasma were reduced and decreased significantly (p < 0.01) in green tea extract treated mice, compared with untreated group. It can be concluded that green tea extract can protect and maintain renal function during malaria infection, and this extract can be developed for use as a supplement and combination therapy.     

Enhancement of neutral endopeptidase activity in SK-N-SH cells by green tea extract

Green tea extract (EFLA85942) is able to induce specifically the neutral endopeptidase (NEP) activity and to inhibit the proliferation of SK-N-SH cells; the angiotensin-converting enzyme (ACE) activity is not influenced under the same conditions. The treatment of the cells with arabinosylcytosine and green tea extract results in a strong enhancement of cellular NEP activity whereas cellular ACE activity was not changed significantly, indicating a green tea extract-specific regulation of NEP expression. Because of its role in the degradation of amyloid beta peptides this enzyme induction of NEP by long term treatment with green tea extract may have a beneficial effect regarding the prevention of forming amyloid plaques.     

Pectin lyase production by Penicillium griseoroseum: Effect of tea extract, caffeine, yeast extract, and pectin

Summary Mycelial growth and production of extracellular pectin lyase by Penicillium griseoroseum at different concentrations of inducers were investigated. The fungus was cultured in mineral medium using sucrose as a carbon source and caffeine, yeast extract, tea extract or pectin as inducers. Caffeine, yeast extract and tea extract in the presence of sucrose, and tea extract alone were capable of inducing pectin lyase in P. griseoroseum, even at low concentrations.     

Green tea extract improves endurance capacity and increases muscle lipid oxidation in mice

Green tea contains a high level of polyphenolic compounds known as catechins. We investigated the effects of green tea extract (GTE), which is rich in catechins, on endurance capacity, energy metabolism, and fat oxidation in BALB/c mice over a 10-wk period. Swimming times to exhaustion for mice fed 0.2-0.5% (wt/wt) GTE were prolonged by 8-24%. The effects were dose dependent and accompanied by lower respiratory quotients and higher rates of fat oxidation as determined by indirect calorimetry. In addition, feeding with GTE increased the level of beta-oxidation activity in skeletal muscle. Plasma lactate concentrations in mice fed GTE were significantly decreased after exercise, concomitant with increases in free fatty acid concentrations in plasma, suggesting an increased lipid use as an energy source in GTE-fed mice. Epigallocatechin gallate (EGCG), a major component of tea catechins, also enhanced endurance capacity, suggesting that the endurance-improving effects of GTE were mediated, at least in part, by EGCG. The beta-oxidation activity and the level of fatty acid translocase/CD36 mRNA in the muscle was higher in GTE-fed mice compared with control mice. These results indicate that GTE are beneficial for improving endurance capacity and support the hypothesis that the stimulation of fatty acid use is a promising strategy for improving endurance capacity.     

Enzymatic hydrolysis of green tea seed extract and its activity on 5alpha-reductase inhibition

Two kaempferol glycosides were isolated from green tea seed extract (GTSE). After conducting a structure analysis, these two compounds were identified as kaempferol-3-O-[2-O-beta-D-galactopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside (compound 1) and kaempferol-3-O-[2-O-beta-D-xylopyranosyl-6-O-alpha-L-rhanmopyranosyl]-beta-D-glucopyranoside (compound 2). These two compounds were hydrolysed by o-glycolytic enzymes for the production of kaempferol. After performing several reactions, we found the optimum enzyme combination, a reaction with beta-galactosidase and hesperidinase. Finally, we produced kaempferol of above 95% purity. The 5alpha-reductase inhibition activities of GTSE hydrolysate (GTSE-H) containing kaempferol were evaluated by the contact cell-based metabolic method using a stable HEK 293 cell line. GTSE-H showed a good inhibition effect on HEK 293 cell lines both type 1 and type 2 on 5alpha-reductase. Especially, GTSE-H inhibited type 2 with kaempferol content dependency. The results indicate that the inhibition activity of hydrolysate on 5alpha-reductase type 2 increases in accordance with kaempferol content.     

A polyphenolic extract from green tea leaves activates fat browning in high-fat-diet-induced obese mice

Fat browning has emerged as an attractive target for the treatment of obesity and related metabolic disorders. Its activation leads to increased energy expenditure and reduced adiposity, thus contributing to a better energy homeostasis. Green tea extracts (GTEs) were shown to attenuate obesity and low-grade inflammation and to induce the lipolytic pathway in the white adipose tissue (WAT) of mice fed a high-fat diet. The aim of the present study was to determine whether the antiobesity effect of an extract from green tea leaves was associated with the activation of browning in the WAT and/or the inhibition of whitening in the brown adipose tissue (BAT) in HF-diet induced obese mice. Mice were fed a control diet or an HF diet supplemented with or without 0.5% polyphenolic GTE for 8 weeks. GTE supplementation significantly reduced HF-induced adiposity (WAT and BAT) and HF-induced inflammation in WAT. Histological analysis revealed that GTE reduced the adipocyte size in the WAT and the lipid droplet size in the BAT. Markers of browning were induced in the WAT upon GTE treatment, whereas markers of HF-induced whitening were reduced in the BAT. These results suggest that browning activation in the WAT and whitening reduction in the BAT by the GTE could participate to the improvement of metabolic and inflammatory disorders mediated by GTE upon HF diet. Our study emphasizes the importance of using GTE as a nutritional tool to activate browning and to decrease fat storage in all adipose tissues, which attenuate obesity.     

Green tea extract improves running endurance in mice by stimulating lipid utilization during exercise

A series of polyphenols known as catechins are abundant in green tea, which is consumed mainly in Asian countries. The effects of catechin-rich green tea extract (GTE) on running endurance and energy metabolism during exercise in BALB/c mice were investigated. Mice were divided into four groups: nonexercise control, exercise control (Ex-cont), exercise+0.2% GTE, and exercise+0.5% GTE groups. Treadmill running time to exhaustion, plasma biochemical parameters, skeletal muscle glycogen content, beta-oxidation activity, and malonyl-CoA content immediately after exercise were measured at 8-10 wk after the initiation of the experiment. Oxygen consumption and respiratory exchange ratio were measured using indirect calorimetry. Running times to exhaustion in mice fed 0.5% GTE were 30% higher than in Ex-cont mice and were accompanied by a lower respiratory exchange ratio, higher muscle beta-oxidation activity, and lower malonyl-CoA content. In addition, muscle glycogen content was high in the GTE group compared with the Ex-cont group. Plasma lactate concentrations in mice fed GTE were significantly lower after exercise, concomitant with an increase in free fatty acid concentrations. Catechins, which are the main constituents of GTE, did not show significant effects on peroxisome proliferator-activated receptor-alpha or delta-dependent luciferase activities. These results suggest that the endurance-improving effects of GTE were mediated, at least partly, by increased metabolic capacity and utilization of fatty acid as a source of energy in skeletal muscle during exercise.     

Diversity of lactic acid bacteria from Miang,a traditional fermented tea leaf in northern Thailand and their tannin-tolerant ability in tea extract

The microbiota of lactic acid bacteria (LAB) in thirty-five samples of Miang, a traditional fermented tea leaf product, collected from twenty-two different regions of eight provinces in upper northern Thailand was revealed through the culture-dependent technique. A total of 311 presumptive LAB strains were isolated and subjected to clustering analysis based on repetitive genomic element-PCR (rep-PCR) fingerprinting profiles. The majority of the strains belonged to the Lactobacillus genera with an overwhelming predominance of the Lb. plantarum group. Further studies of species-specific PCR showed that 201 of 252 isolates in the Lb. plantarum group were Lb. plantarum which were thus considered as the predominant LAB in Miang, while the other 51 isolates belonged to Lb. pentosus. In contrast to Lb. plantarum, there is a lack of information on the tannase gene and the tea tannin-tolerant ability of Lb. pentosus. Of the 51 Lb. pentosus isolates, 33 were found to harbor the genes encoding tannase and shared 93-99% amino acid identity with tannase obtained from Lb. pentosus ATCC 8041^T. Among 33 tannase gene-positive isolates, 23 isolates exhibited high tannin- tolerant capabilities when cultivated on de Man Rogosa and Sharpe agar-containing bromocresol purple (0.02 g/L, MRS-BCP) supplemented with 20% (v/v) crude tea extract, which corresponded to 2.5% (w/v) tannins. These Lb. pentosus isolates with high tannin-tolerant capacity are expected to be the high potential strains for functional tannase production involved in Miang fermentation as they will bring about certain benefits and could be used to improve the fermentation of tea products.