Effects Of Tea Catechins Research Articles

Rheology of heat-set pudding (emulsion gel) and O/W interface: effects of interaction between tea catechins and egg yolk plasma at O/W interface

Herein, the effects of tea catechins (TCs) on the rheological properties of a model heat-set pudding (emulsion gel) were investigated. A combination of skimmed milk powder, egg white powder, egg yolk, egg yolk plasma, egg yolk granules, coconut oil, and TCs was used as the raw material for the model pudding. Viscoelastic measurements showed that the storage modulus G′ of the TC-containing model pudding in the range of 10°C–15 °C (each solid fat content in coconut oil ranged from 79% to 71%) was approximately 10-fold higher than that of the model pudding without TCs. Furthermore, a very high Gʹ could be obtained when egg yolk plasma and coconut oil were used in the raw material for the TC-containing model pudding at 10°C–15 °C. Additionally, the results of interfacial tension and viscoelasticity measurements at the oil-water interface suggested that the interfacial structure changes due to the interaction between egg yolk plasma and TCs contributed to a very high G′ for the TCs-containing model pudding in the range of 10°C–15 °C.

The effect of tea catechins on the forensic identification of urine: Urine camouflage to evade drug tests

BackgroundWe encountered a urine sample suspected of being mixed with tea, submitted by a suspect attempting to camouflage illegal drugs. Although urine should turn reddish-pink during a urea test with p-Dimethylaminocinnamaldehyde (DAC), this suspect’s sample exhibited a blue coloration when tested with DAC. AimOur aim was to examine the influence and mechanism of green tea on various urine identification tests. ResultsOur examination revealed that DAC forms a compound with the urea in urine, resulting in a reddish pink coloration with a molecular weight of 217. However, it has been reported that DAC binds to polyphenols such as catechin. In the case of catechin, DAC binds to the C8 position, forming a compound that exhibits the highest absorption at 640 nm and appears blue. we investigated the effect of urine from volunteers who had consumed a large amount of catechin on the urea test with DAC. Additionally, we carried out quantitative analysis of catechin in urine by LC-MS/MS after enzymatic treatment with β-glucuronidase. The concentration of urinary excreted catechin reached its peak approximately 3 to 4 h after ingestion. During the DAC test, urine samples collected 3 to 4 h after catechin ingestion displayed a bluish pink color, but not the blue color observed in the original suspect sample. ConclusionThis study investigated the impact of catechin on urine tests, revealing that a blue color in the DAC test indicates a high likelihood of camouflage by the suspect.

Effect of tea catechins on gut microbiota in high fat diet-induced obese mice.

Tea catechins have been shown to have beneficial effects on the alleviation of obesity, the prevention of diabetes, and the amelioration of metabolic syndrome. The purpose of the present work is to explore the underlying mechanisms linking the intestinal microbiota and anti-obesity benefits of green tea, oolong tea, and black tea catechins in C57BL/6J mice fed with a high-fat diet (HFD). The results indicated that, after the dietary intake of three tea catechins, obesity and low-grade inflammation were significantly alleviated. Hepatic steatosis was prevented, and this was accompanied by the upregulation of the mRNA and protein expressions of hepatic peroxisome proliferator-activated receptor α (PPARα). Metagenomic analysis of fecal samples suggested that the three tea catechins similarly changed the microbiota in terms of overall structure, composition, and protein functions by regulating the metabolites, facilitating the generation of short-chain fatty acids (SCFAs), and repressing lipopolysaccharides. The anti-obese properties of three tea catechins were partially mediated by their positive effect on gut microbiota, hepatic steatosis alleviation, and anti-inflammatory activity. © 2023 Society of Chemical Industry.

The Effect of Tea Catechins on Natural Killer Cell Activity in the Elderly: A Pilot Study

The Effect of Tea Catechins on Natural Killer Cell Activity in the Elderly: A Pilot Study

Effect of tea catechins with caffeine on energy expenditure in middle-aged men and women: a randomized, double-blind, placebo-controlled, crossover trial

PurposeIt has been reported that tea catechins increase energy metabolism, but their effect on resting metabolic rate (RMR) remains under debate. This study aimed to examine the effect of repeated intake of tea catechins on energy metabolism in the resting state in middle-aged men and women.MethodsA total of 30 middle-aged men and women [13 women; age (mean ± SD) 52 ± 4 years; BMI 21.9 ± 2.2 kg/m2] were recruited. A randomized, double-blind, crossover study was conducted using a tea catechin-enriched beverage (611 mg catechins, 88 mg caffeine) and a placebo beverage (0 mg catechins, 81 mg caffeine) as test beverages. After 2 weeks of continuous test beverage intake, fasting RMR and energy expenditure (EE) after the ingestion of test beverage were measured. Measurements of forehead temperature (proxy for core temperature) and skin temperature were also obtained simultaneously.ResultsAmong participants who underwent measurements, 26 (10 women; mean age 52 ± 4 years; mean BMI 22.1 ± 2.1 kg/m2) were analyzed. The EE increased significantly after ingestion of the tea catechin beverage compared with the placebo beverage (placebo treatment: 5502 ± 757 kJ/day; catechin treatment: 5598 ± 800 kJ/day; P = 0.041). No between-treatment differences in fasting RMR or the respiratory quotient were detected. In addition, the forehead and skin temperature did not differ significantly between the placebo and catechin treatments.ConclusionThis study revealed that continuous intake of tea catechins with caffeine for 2 weeks significantly increased EE after ingestion of the tea catechin but not fasting RMR in middle-aged men and women.Clinical Trial Registry number and websiteThis trial was registered at www.umin.ac.jp/ctr/ as UMIN000025810 and UMIN000025811.

The Effects of Tea Catechins on Bone Metabolism

The Effects of Tea Catechins on Bone Metabolism

Effects of Tea Catechins on Alzheimer's Disease: Recent Updates and Perspectives.

Alzheimer’s disease (AD) is one of the most common neurodegenerative disorders worldwide. Its incidence is gradually increasing because of an aging demographic. Therefore, AD prevention and modification is important to improve the health status of older adults. Oxidative stress is a component of the pathological mechanisms underlying AD. It is caused by a disruption of the balance between reactive oxygen species and antioxidant molecules. This imbalance also causes neuroinflammation. Catechins, which are bioactive components of tea, have antioxidative and anti-inflammatory effects. Moreover, other potential properties related to AD prevention and modification have been reported in in vitro and in vivo studies. Several clinical studies have also been conducted to date. The current review summarizes recent updates and perspectives of the effects of catechins on AD based on the molecular mechanisms and related clinical studies.

Effect of Tea Catechins on Folate Analysis in Green Tea by Microbiological Assay

Green tea is thought to be a primary source of folate in the Japanese diet, based on folate content analyzed by a microbiological assay. Green tea also contains high amount of catechins, in particular, epigallocatechin gallate (EGCg), which was demonstrated to be able to inhibit the digestive enzyme activities and microbial growth in the folate assay. In the present study, we examined whether tea catechins interfered with components of the folate assay for green tea. A marked inhibitory effect of EGCg on microbial growth was observed at an inhibitory concentration of higher than 10 μg/mL. Tea catechins without the galloyl moiety did not show an inhibitory effect. EGCg inhibited the activity of the three enzymes used for assay sample preparation at an inhibitory concentration of higher than 750 μg/mL for α-amylase, 1,000 μg/mL for protease, and 50 μg/mL for conjugase. However, with each step of the assay, the actual concentration of EGCg was decreased to below the inhibitory concentration of each analytical step. Lack of influence of EGCg on green tea folate assay was confirmed by an addition of folate standard in tea infusion. These results suggested that tea catechins have no practical impact on folate analysis in green tea, using the general microbiological assay.

In Silico Validation for the Modulatory Effect of Tea Catechins on Erythrocyte Na<sup>+</sup>/K<sup>+</sup>-ATPase

In Silico Validation for the Modulatory Effect of Tea Catechins on Erythrocyte Na<sup>+</sup>/K<sup>+</sup>-ATPase

Effects of catechin and α-tocopherol addition on the autoxidative stability of diacylglycerol oil derived from an olive oil and perilla oil mixture

The effects of tea catechin and α-tocopherol addition (1 mM) on the oxidative stability of oleic and linolenic acid-rich diacylglycerol (DAG) oil derived from an extra virgin olive oil and perilla oil mixture (6:4, w/w) were evaluated. Oil was oxidized at 50°C for 10 days, after which oxidation was evaluated based on headspace oxygen consumption and peroxide values (POV). The polyphenol and tocopherol contents were also monitored. Addition of catechin did not affect the oxygen consumption or POV of DAG oil, whereas α-tocopherol acted as a prooxidant. Addition of antioxidants had no significant (p>0.05) effect on the fatty acid composition of the oil. Degradation of γ-tocopherol during oil oxidation was inhibited by addition of α-tocopherol, and addition of antioxidants inhibited polyphenol degradation. The autoxidative stability of DAG oil can be improved using polar rather than non-polar antioxidants.

Effects of Tea Catechins on Cancer Signaling Pathways.

The inhibitory activities of tea catechins against carcinogenesis and cancer cell growth have been demonstrated in a large number of laboratory studies. Many mechanisms for modulating cancer signaling and metabolic pathways have been proposed based on numerous studies in cell lines with (-)-epigallocatechin-3-gallate, the most abundant and active tea catechin. Nevertheless, the molecular basis for the proposed mechanisms and whether these mechanisms indeed contribute to the anticancer activities in vivo are not clearly known. This chapter reviews the basic redox properties of tea catechins, their binding to key enzymes and signal transduction proteins, and other mechanisms that lead to suppression of cell proliferation, increased apoptosis, and inhibition of angiogenesis. More weight is put on studies in vivo over experiments in vitro. It also discusses key issues involved in extrapolating results from cell line studies to mechanistic insights in vivo.

Abstract A73: Evaluating tissue biomarker effects of an oral green tea extract, polyphenon E, using reverse phase protein array in women with operable breast cancer

Abstract Background: Numerous epidemiologic studies and experimental data support potential anti-tumor effects of green tea and its main component, epigallocatechin-3-gallate (EGCG), in breast cancer. However, there is limited data on the effects of tea catechins on breast cancer in human intervention trials. The purpose of this study is to evaluate tumor proteomic changes after short-term pre-surgical administration of an oral green tea extract, Polyphenon E (Poly E), in women with operable breast cancer using reverse phase protein array (RPPA). Methods: This is a phase II single-arm open-label trial of oral Poly E 800 mg daily for 2-4 weeks in women with histologically-confirmed breast cancer on core biopsy who were scheduled for surgical resection. Formalin-fixed paraffin-embedded (FFPE) tumor tissue from the diagnostic core biopsy (pre-treatment) and surgical resection (post-treatment) were analyzed for expression of the Ki-67 proliferation index, estrogen receptor (ER), progesterone receptor (PR), and HER2 by immunohistochemistry (IHC). Protein was extracted for RPPA analysis of 161 proteins, including components of the PI3K/AKT and MAPK pathways. Women were matched by age, breast cancer stage, ER/PR/HER2 status, and time interval between breast biopsy and surgery to untreated historical controls. Paired t-test was used to calculate changes in protein markers before and after Poly E treatment and 2-sample t-test to compare biomarker changes in the treatment and no treatment groups. All statistical analyses were 2-sided and performed using SAS version 9.1. Results: From Feb 2008 to Sept 2009, 25 women were enrolled and 21 were evaluable. Median age: 50 years (range, 33-71); White/Hispanic/Black (%): 44/48/7; Stage 0/I/II/III (%): 11/48/30/11; hormone receptor +/- (%): 85/15. Mean duration on Poly E was 20 days (range, 13-36). We demonstrated significant correlations between RPPA and IHC for Ki-67 (0.46, P<0.0001), ER (0.45, P=0.0017), PR (0.46, P=0.0014), and a trend for HER2 (0.28, P=0.0923). Poly E treatment did not cause a significant decrease in Ki-67 compared to untreated controls (mean absolute change, -0.5% vs. +2.6%, P=0.83). In the Poly E-treated group, the RPPA results showed significant modulation of apoptosis and PI3K/AKT pathway proteins (P<0.05). After Bonferroni correction to adjust for multiple comparisons (P<0.00031), 11 markers remained statistically significant comparing change from baseline with Poly E treatment: up-regulation of MEK1, JNK2, and p38-MAPK; down-regulation of CDK4, HER2-pY1248, MAPK-pT202-Y204, MIG-6, mTOR-pS2448, PRAS40-pT246, Src-pY416, and Scr-pY527. Compared to untreated controls, the Poly E group had significant changes from baseline in 10 proteins: up-regulation of IRS1, p38-MAPK, Notch1, and YAP; down-regulation of ERCC1, MIG-6, p90RSK-pT359-S363, PRAS40-pT246, Smad3, and Src-pY416 (P<0.05). Conclusions: Short-term administration of Poly E did not significantly decrease proliferation in breast tumor tissue; however, our RPPA data suggests that Poly E may act on alternative signaling pathways. The changes we observed in CDK4, HER2, Src, MAPK, and JNK expression are consistent with preclinical studies of EGCG. This is one of the first human intervention trials to demonstrate the biologic effects of Poly E on growth factor signaling pathways in breast cancer. Citation Format: Kimberly A. Ho, Davida Kornreich, James A. Cardelli, Jerry McLarty, Dawn L. Hershman, Matthew Maurer, Kevin Kalinsky, Bret Taback, Hanina Hibshoosh, Tao Su, Susan F. Refice, Katherine D. Crew. Evaluating tissue biomarker effects of an oral green tea extract, polyphenon E, using reverse phase protein array in women with operable breast cancer. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A73.

Effect of tea catechins on regulation of cell proliferation and antioxidant enzyme expression in H2O2‐induced primary hepatocytes of goat in vitro

Tea catechins (TC) are polyphenols that have potent antioxidant activity. The objectives of this study were to determine the effects of TC on antioxidant status of hepatocytes challenged with H2 O2 . Primary hepatocytes of goat were exposed to 1 mm H2 O2 without or with 5, 50 and 500 μg/ml TC. The cells were harvested at 48 h post-treatment to determine effects of TC on proliferation, apoptotic features and membrane integrity of cells, and expression of genes and activities of antioxidant enzymes. H2 O2 exposure caused damage to cells (p < 0.001). A lower concentration of TC (5 μg/ml) displayed a protective effect by inhibiting exorbitant cell proliferation and DNA degradation. Both H2 O2 exposure and TC pre-incubation affected expression of antioxidant enzymes at mRNA and protein levels (p < 0.001). The activities of catalase (CAT) (p = 0.027), CuZn-superoxide dismutase (CuZn-SOD) (p < 0.001) and glutathione peroxidase (GPx) (p < 0.001) increased with TC pre-incubation followed by H2 O2 challenge. Changes of CuZn-SOD activity induced by H2 O2 and TC basically paralleled the changes in the corresponding mRNA and protein levels, but the correlation in CAT and GPx expression displayed slightly different patterns at different concentrations of TC. These findings infer that oxidative stress can induce deleterious cellular responses and this unfavourable condition may be alleviated by treatment with TC.

Effect of Tea Catechins on Regulation of Antioxidant Enzyme Expression in H2O2-Induced Skeletal Muscle Cells of Goat in Vitro

Skeletal muscle cells (SMCs) of goats were stress induced with 1 mM H(2)O(2) in the absence or presence of 0.5, 5, and 50 μg/mL tea catechins (TCs) incubation. Cells were harvested at 48 h postincubation with TCs to investigate the effects of TCs on cell proliferation, cell membrane integrity, antioxidant enzyme activities, and antioxidant enzyme genes and protein expression levels. Results showed that H(2)O(2) induction inhibited cell proliferation with or without TC incubation; moreover, the inhibition effect was enhanced in the presence of TCs (P < 0.001). H(2)O(2)-induced stress increased the lactate dehydrogenase (LDH) activity in the absence or presence of TC incubation, but concentrations of TCs, less than 5 μg/mL, showed protective functions against LDH leakage than in other H(2)O(2)-induced treatments. The catalase (CAT) activity increased when SMCs were stress induced with H(2)O(2) in the absence or presence of TC incubation (P < 0.001). H(2)O(2)-induced stress decreased CuZn superoxide dismutase (CuZn-SOD) and glutathione peroxidase (GPx) activities, whereas this effect was prevented by incubation with TCs in a concentration-dependent manner. H(2)O(2)-induced stress with or without TC incubation had significant effects on mRNA and protein expression levels of CAT, CuZn-SOD, and GPx (P < 0.001). CAT and CuZn-SOD mRNA expression levels were increased by different concentrations of TC incubation, and this tendency was basically consistent with corresponding protein expression levels. The GPx mRNA expression level increased with a low concentration of TCs but decreased with concentrations greater than 5 μg/mL of TCs, whereas GPx protein expression in all TC-incubated groups was lower than in the control treatment. The current findings imply that TCs had an inhibitory effect on cell proliferation and enhanced damage to the cell membrane integrity, but TCs affected antioxidant status in SMCs by modulating antioxidant enzyme activities at mRNA and protein expression levels.

Quality Characteristics of Raw and Cooked Spent Hen Pectoralis major Muscle During Chilled Storage: Effect of Tea Catechins

Quality Characteristics of Raw and Cooked Spent Hen Pectoralis major Muscle During Chilled Storage: Effect of Tea Catechins

Effects of Tea Catechins on Oral Odor and Dental Plaque

Effects of Tea Catechins on Oral Odor and Dental Plaque

Effects of Tea Catechins, Epigallocatechin, Gallocatechin, and Gallocatechin Gallate, on Bone Metabolism

In this study, three tea catechins, epigallocatechin (EGC), gallocatechin (GC), and gallocatechin gallate (GCG), were investigated for their effects on bone metabolism. The effects of the tea catechins on bone formation were evaluated using cultured rat osteoblast-like osteosarcoma cell line UMR-106. EGC stimulated alkaline phosphatase activity significantly at concentrations of 10 and 20 microM. The amount of mineralization also increased significantly with EGC. On another cell culture platform, EGC significantly inhibited osteoclast formations from RAW 264.7 cells upon receptor activation of nuclear factor-kappaB ligand induction on the fourth day of treatment, at a concentration of 10 microM. EGC also dose-dependently inhibited the mRNA expression of tatrate-resistant acid phosphatase. GC and GCG could decrease osteoclastogenesis at 20 microM. The present study illustrated that the tea catechins, EGC in particular, had positive effects on bone metabolism through a double process of promoting osteoblastic activity and inhibiting osteoclast differentiations.

Effects of Tea Catechins on Inflammation-Related Cardiovascular Diseases

Effects of Tea Catechins on Inflammation-Related Cardiovascular Diseases

Effects of Tea Catechins on the Gastrointestinal Mucosa in Rats

Although tea catechins are known to exert a potent antiulcer effect on the alimentary tract, there is scant information concerning their effects on normal mucus cell functions. Using original anti-mucin monoclonal antibodies, we studied the influences of long-term administration of catechins on the quantity and quality of mucin in rat gastrointestinal mucosa. Administration of 0.5% tea catechins significantly increased the mucin content of the ileum, but not the stomach. An enzyme-linked immunosorbent assay (ELISA) showed no remarkable qualitative changes in gastric mucin, but a selective increase and decrease in sulfo- and sialomucins, respectively, in the ileum of rats administered catechins. The ELISA results were consistent with both the immunohistochemical findings and the high-iron diamine-alcian blue staining pattern. These findings indicate that tea catechins modulate ileal mucin metabolism in the ileal mucosa, suggesting that further studies focusing on the ileal epithelium will assist in further elucidation of the mechanism of catechin effects.

Effect of tea catechins on body fat accumulation in rats fed a normal diet

Although it is known that tea catechins exert potent effects in obese subjects, there is scant information concerning these effects on body weight gain and body fat accumulation in the non-obese. We studied normal rats fed a normal diet and water containing either 0.1% or 0.5% tea catechins to examine the effects on body fat content and serum cholesterol levels, as well as evaluating whether the effect is related to bile acids, which in recent years have emerged as an inducer of energy expenditure. The administration of 0.5% catechins decreased the accumulation of body fat and the serum levels of cholesterol and bile acids. These results indicate that tea catechins modulate lipid metabolism not only in obese subjects, but also in the non-obese.