scholarly journals Green Tea Extract-Induced Lethal Toxicity in Fasted but Not in Nonfasted Dogs

2010 ◽  
Vol 30 (1) ◽  
pp. 19-20 ◽  
Author(s):  
Kuei-Meng Wu ◽  
Jiaqin Yao ◽  
Daniel Boring
Keyword(s):  
Green Tea ◽  
Area Under The Curve ◽  
Epigallocatechin Gallate ◽  
The United States ◽  
Reproductive Organs ◽  
Green Tea Extract ◽  
Renal Tubules ◽  
Organ Systems ◽  
Tea Drinking ◽  
Tea Extract

Recent chronic toxicity studies performed on green tea extracts in fasted dogs have revealed some unique dose-limiting lethal liver, gastrointestinal, and renal toxicities. Key findings included necrosis of hepatic cells, gastrointestinal epithelia and renal tubules, atrophy of reproductive organs, atrophy and necrosis of hematopoietic tissues, and associated hematological changes. The polyphenol cachetins (a mixture of primarily epigallocatechin gallate [≥55%]; plus up to 10% each of epigallocatechin, epicatechin, and epigallocatechin gallate) appeared to be the causative agents for the observed toxicities because they are the active ingredients of green tea extract studied. Conduct of the study in nonfasted dogs under the same testing conditions and dose levels showed unremarkable results. Assuming both studies were valid, at the identified no observed adverse effect levels (NOAEL) of each study, systemic exposures (based on area under the curve [AUC]) were actually lower in fasted than nonfasted dogs, suggesting that fasting may have rendered the target organ systems potentially more vulnerable to the effects of green tea extract. The toxicity mechanisms that produced lethality are not known, but the results are scientifically intriguing. Because tea drinking has become more popular in the United States and abroad, the mode of action and site of action of green tea extract-induced lethal toxicities during fasting and the role of other phytochemical components of Folia Camellia sinensis (including nonpolyphenol fractions, which are often consumed when whole-leaf products are presented) warrant further investigation.

Green tea extract and its major component epigallocatechin gallate inhibits hepatitis B virus in vitro

2008 ◽  
Vol 78 (3) ◽  
pp. 242-249 ◽  
Author(s):  
Jun Xu ◽  
Jue Wang ◽  
Fei Deng ◽  
Zhihong Hu ◽  
Hualin Wang
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Green Tea ◽  
Epigallocatechin Gallate ◽  
Green Tea Extract ◽  
B Virus ◽  
Tea Extract

Potential role of green tea extract and epigallocatechin gallate in preventing bisphenol A-induced metabolic disorders in rats: Biochemical and molecular evidence

Phytomedicine ◽  
2021 ◽  
pp. 153754
Author(s):  
Mahdieh Sadat Mohsenzadeh ◽  
Bibi Marjan Razavi ◽  
Mohsen Imenshahidi ◽  
Seyed Abbas Tabatabaee Yazdi ◽  
Seyed Ahmad Mohajeri ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Green Tea ◽  
Metabolic Disorders ◽  
Potential Role ◽  
Epigallocatechin Gallate ◽  
Green Tea Extract ◽  
Molecular Evidence ◽  
Tea Extract

scholarly journals Catechin Bioavailability Is Reduced in Obese Persons Without Altering Gut Microbial-Derived Valerolactones Following Consumption of a Green Tea Extract Confection

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 468-468
Author(s):  
Geoffrey Sasaki ◽  
Yael Vodovotz ◽  
Zhongtang Yu ◽  
Richard Bruno
Keyword(s):  
Green Tea ◽  
Plasma Concentrations ◽  
Area Under The Curve ◽  
Relative Bioavailability ◽  
Green Tea Extract ◽  
Maximum Plasma ◽  
Gut Permeability ◽  
Epicatechin Gallate ◽  
Obesity Status ◽  
Tea Extract

Abstract Objectives Green tea extract (GTE) protects against obesity in rodents by reducing gut permeability that otherwise provokes endotoxemia-mediated inflammation. However, whether obesity affects catechin bioavailability and microbial metabolism is unknown. We hypothesized that obesity will reduce catechin bioavailability by increasing microbial biotransformation of catechins. Methods Obese persons (n = 10 M/7F; 33.5 ± 0.7 kg/m2) and age-matched healthy persons (n = 10 M/9F; 21.7 ± 0.4 kg/m2) completed a pharmacokinetics (PK) trial in which a GTE confection [290 mg epigallocatechin gallate (EGCG), 87 mg epigallocatechin (EGC), 39 mg epicatechin (EC), 28 mg epicatechin gallate (ECG)] was ingested prior to collecting plasma at 0, 0.25, 0.5, 1, 2, 3, 5, 8, 10, and 12 h and urine from 0–4, 4–8, 8–12, and 12–24 h. Stool samples were collected and gut permeability was assessed prior to the 12-h PK trial. Plasma and urinary catechin/catechin-derived microbial metabolites were assessed following enzymatic hydrolysis by LC-MS. Results Regardless of health status, relative bioavailability, based on plasma area under the curve (AUC0–12 h), of GTE catechins were: EGCG > EGC > ECG > EC. However, obese persons had 24–27% lower plasma AUC0–12 h for the four catechins compared to lean persons (P < 0.05). They also had 18–36% lower maximum plasma concentrations (Cmax) of GTE catechins but 12 h plasma catechin concentrations were unaffected by obesity status (P > 0.05). 3ʹ,4ʹ-γ-valerolactone (3,4-VL) was detected in the plasma of all participants, while 3ʹ,4ʹ,5ʹ-γ-valerolactone (3,4,5-VL) was detected in 74% and 82% of lean and obese persons, respectively. Plasma AUC0–12 h for these VL metabolites did not differ by obesity status. EGC, EC, 3,4-VL, and 3,4,5-VL, but not EGCG and ECG, were primarily present in urine and urinary total VLs were increased compared with total urinary catechins. However, 24-h urinary excretion of catechins and VLs were unaffected by obesity. Conclusions Obesity reduces GTE catechin bioavailability and Cmax independent of any change in VL metabolite appearance or urinary elimination of catechins, suggesting a gut-level mechanism that limits catechin absorption. Funding Sources Supported by USDA-NIFA and the Foods for Health Discovery Theme at The Ohio State University.

Green tea extract and its major polyphenol (−)-epigallocatechin gallate improve muscle function in a mouse model for Duchenne muscular dystrophy

2006 ◽  
Vol 290 (2) ◽  
pp. C616-C625 ◽  
Author(s):  
Olivier M. Dorchies ◽  
Stéphanie Wagner ◽  
Ophélie Vuadens ◽  
Katri Waldhauser ◽  
Timo M. Buetler ◽  
...  
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mouse Model ◽  
Green Tea ◽  
Epigallocatechin Gallate ◽  
Green Tea Extract ◽  
Triceps Surae ◽  
Muscle Quality ◽  
Muscle Adaptation ◽  
Tea Extract

Duchenne muscular dystrophy is a frequent muscular disorder caused by mutations in the gene encoding dystrophin, a cytoskeletal protein that contributes to the stabilization of muscle fiber membrane during muscle activity. Affected individuals show progressive muscle wasting that generally causes death by age 30. In this study, the dystrophic mdx 5Cv mouse model was used to investigate the effects of green tea extract, its major component (−)-epigallocatechin gallate, and pentoxifylline on dystrophic muscle quality and function. Three-week-old mdx 5Cv mice were fed for either 1 or 5 wk a control chow or a chow containing the test substances. Histological examination showed a delay in necrosis of the extensor digitorum longus muscle in treated mice. Mechanical properties of triceps suræ muscles were recorded while the mice were under deep anesthesia. Phasic and tetanic tensions of treated mice were increased, reaching values close to those of normal mice. The phasic-to-tetanic tension ratio was corrected. Finally, muscles from treated mice exhibited 30–50% more residual force in a fatigue assay. These results demonstrate that diet supplementation of dystrophic mdx 5Cv mice with green tea extract or (−)-epigallocatechin gallate protected muscle against the first massive wave of necrosis and stimulated muscle adaptation toward a stronger and more resistant phenotype.

The MIRACLE trial: A randomized, controlled trial comparing green tea extract versus placebo for the prevention of metachronous colon adenomas in a screening population.

2015 ◽  
Vol 33 (3_suppl) ◽  
pp. TPS786-TPS786 ◽  
Author(s):  
Thomas Jens Ettrich ◽  
Julia Stingl ◽  
Rainer Muche ◽  
Katrin Claus ◽  
Baerbel Reiser ◽  
...  
Keyword(s):  
Green Tea ◽  
Controlled Trial ◽  
Epigallocatechin Gallate ◽  
Genetic Alterations ◽  
Colorectal Polyps ◽  
Green Tea Extract ◽  
Colorectal Adenomas ◽  
Tissue Samples ◽  
Increased Risk ◽  
Tea Extract

TPS786 Background: Prevention of colorectal cancer is a major health care issue. After polypectomy there is an increased risk of polyp recurrence and various means of chemoprevention have been tried to prevent this. NSAIDs have been shown to be effective but confer side effects such as gastrointestinal bleeding. Nutraceuticals such as polyphenols from tea plants have demonstrated remarkable therapeutic and preventive effects in molecular, epidemiological and some clinical trials. However, their value in preventing colorectal polyps has not been demonstrated in a large, randomized trial. The beneficial safety profile of decaffeinated green tea extract and accumulating evidence of its cancer preventive potential justify and require, in our view, a validation of this compound for the nutriprevention of colorectal adenoma. Good accessibility and low costs might render this neutraceutical a top candidate for wider use as nutritional supplement in colon cancer prevention. Methods: Randomized, double blinded, placebo-controlled, multicenter trial. After a one month run-in period with verum, 918 patients (age: 50-80 years) who have undergone polypectomy within the last 6 months will be randomized to receive either decaffeinated green tea extract (containing 150 mg epigallocatechin gallate (EGCG) two times daily) or placebo over a period of three years. Primary outcome: Incidence of metachronous colorectal adenomas (tubulovillous, tubular, villous, serrated lesions) at the 3 year follow-up colonoscopy. Secondary outcomes: Occurrences, number, localization, size and histological subtypes of adenomas, frequency of colorectal carcinoma. In addition, genetic and biochemical biomarkers in blood samples and genetic alterations (Ras, B-raf, microRNAs) in tissue samples of adenomas will be analyzed (biobanking subprojects). Additionally, nutrikinetics and nutrigenetics of EGCG and other catechins will be assessed in healthy volunteers. Patient recruitment has started in November 2011. At September 2014, 785 patients were recruited and 651 patients were randomized. We expect the last patient out in Spring 2018. (Trial identifier NCT01360320) Clinical trial information: NCT01360320.

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

2005 ◽  
Vol 288 (3) ◽  
pp. R708-R715 ◽  
Author(s):  
Takatoshi Murase ◽  
Satoshi Haramizu ◽  
Akira Shimotoyodome ◽  
Azumi Nagasawa ◽  
Ichiro Tokimitsu
Keyword(s):  
Fatty Acid ◽  
Green Tea ◽  
Epigallocatechin Gallate ◽  
Fat Oxidation ◽  
Green Tea Extract ◽  
Endurance Capacity ◽  
Oxidation Activity ◽  
Tea Extract ◽  
High Level ◽  
Dose Dependent

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 β-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 β-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.

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