Plasma Epigallocatechin Gallate Research Articles

The Effect of Green Tea Extract Supplementation and Different Catechol-O-Methyltransferase Genotypes on Plasma Catechins Concentrations in Women Who Are Post-menopause

ObjectivesTo determine if oral intake of green tea extract (GTE) capsules increases plasma concentrations of green tea catechins, and if genotypes impact changes in plasma concentrations of catechins. MethodsThis study was a secondary analysis of the Minnesota Green Tea Trial (MGTT), a randomized, double-blind, placebo-controlled trial. Participants were healthy postmenopausal women receiving GTE capsules with 843.0 mg epigallocatechin gallate (EGCG) or placebo daily for 12 months. In a subset of the participants (n = 178) plasma concentrations of green tea catechins were analyzed at baseline and month 12. Absolute changes in concentrations of plasma catechins including EGCG, epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC) were compared between treatment groups, and between COMT genotypes among those in the GTE group. Findings were stratified by potential confounding factors. ResultsParticipants were mainly white non-Hispanic with a mean ± SD age of 60.13 ± 5.14 years and BMI of 24.97 ± 3.76 kg/m2. Absolute changes from baseline in plasma concentrations of EGCG (46.32 vs. 0.00 nM), ECG (18.39 vs. 0.00 nM), and EC (15.56 vs 0.06 nM) were significantly higher in the GTE than the placebo group, respectively (all Ps < 0.001). After adjusting for age and dietary intakes of fiber and vitamin C, absolute changes from baseline in plasma concentrations of EGCG were significantly greater in the high-activity COMT genotype (G/G) compared to those with the low-activity COMT genotypes (A/A or A/G) in the GTE group (P = 0.048). There was a statistically significant interaction between treatment and total vitamin C intake at baseline for absolute change from baseline of plasma EC (Pint = 0.008). Participants in the GTE group with vitamin C intake above median values at baseline experienced significantly greater positive increases in plasma concentration of EC compared to those in the placebo group. ConclusionsConcentrations of plasma EGCG, ECG, and EC were significantly increased after GTE supplementation for 12 months. COMT genotype may modify circulating EGCG concentrations; the entailed mechanism remains to be investigated. Funding SourcesNIH (Grant R01 CA127236).

Bioavailability of Epigallocatechin Gallate Administered With Different Nutritional Strategies in Healthy Volunteers.

The flavanol epigallocatechin gallate (EGCG) is being tested for the treatment of several diseases in humans. However, its bioavailability and pharmacokinetic profile needs a better understanding to enable its use in clinical trials. There is no consensus on the most appropriate concentration of EGCG in the body to obtain the maximum therapeutic effects. Therefore, the aim of this study is to analyze the bioavailability of EGCG orally administered alone or with different food supplements after overnight fasting in order to determine its optimal conditions (high concentrations in blood and the lowest interindividual variations) to be used as a pharmacological tool in human trials. Ten healthy volunteers (5 men and 5 women) aged 25 to 35 years were recruited prospectively. Three series of clinical experiments with a washout period of seven days among each were performed: (1) Teavigo® (EGCG extract) alone, (2) Teavigo® with a standard breakfast, and (3) FontUp® (Teavigo® commercially prepared with fats, carbohydrates, proteins, vitamins, and minerals). Blood samples were collected at 0, 30, 60, 90, 120, 180, 240, and 360 min after EGCG intake. Free EGCG in plasma was measured using a liquid chromatography and mass spectrometry UPLC-ESI-MS/MS analytical method. The pharmacokinetic variables analyzed statistically were area under the curve (AUC0–360), Cmax, Cav, Cmin, T1/2, and Tmax. EGCG (Teavigo®) alone was the group with higher AUC0–360, Cmax, and Cav both in men (3.86 ± 4.11 µg/mL/kg/6 h; 5.95 ng/mL/kg; 2.96 ng/mL/kg) and women (3.33 ± 1.08 µg/mL/kg/6 h; 6.66 ng/mL/kg; 3.66 ng/mL). Moreover, FontUp® was the group with the highest value of T1/2 both in men (192 ± 66 min) and women (133 ± 28 min). Teavigo® intake after fasting overnight revealed the highest concentration of EGCG in plasma according to its pharmacokinetic profile, indicating that this is an excellent alternative of administration if the experimental design requires good absorption in the gastrointestinal tract. Moreover, EGCG taken along with food supplements (FontUp®) improved the stability of the molecule in the body, being the best choice if the experimental design wants to reduce interindividual variation.

Molecular Rescue of Dyrk1A Overexpression Alterations in Mice with Fontup® Dietary Supplement: Role of Green Tea Catechins.

Epigallocatechin gallate (EGCG) is an inhibitor of DYRK1A, a serine/threonine kinase considered to be a major contributor of cognitive dysfunctions in Down syndrome (DS). Two clinical trials in adult patients with DS have shown the safety and efficacy to improve cognitive phenotypes using commercial green tea extract containing EGCG (45% content). In the present study, we performed a preclinical study using FontUp®, a new nutritional supplement with a chocolate taste specifically formulated for the nutritional needs of patients with DS and enriched with a standardized amount of EGCG in young mice overexpressing Dyrk1A (TgBACDyrk1A). This preparation is differential with previous one used, because its green tea extract has been purified to up 94% EGCG of total catechins. We analyzed the in vitro effect of green tea catechins not only for EGCG, but for others residually contained in FontUp®, on DYRK1A kinase activity. Like EGCG, epicatechin gallate was a noncompetitive inhibitor against ATP, molecular docking computations confirming these results. Oral FontUp® normalized brain and plasma biomarkers deregulated in TgBACDyrk1A, without negative effect on liver and cardiac functions. We compared the bioavailability of EGCG in plasma and brain of mice and have demonstrated that EGCG had well crossed the blood-brain barrier.

Plasma tea catechins and risk of cardiovascular disease in middle-aged Japanese subjects: The JPHC study

Background and aimsAlthough a potential benefit of drinking green tea has been suggested to reduce the development of cardiovascular disease, no study has investigated the relationship between plasma tea catechin and risk of cardiovascular disease. MethodsA prospective, nested case-control study was conducted to examine the association between plasma tea catechin and risk of stroke and coronary heart disease (CHD) in a cohort of 29,876 men and women aged 40–69 years without history of heart disease, stroke or cancer. Participants completed a survey and donated blood samples between 1990 and 1994, and were followed-up through 2008. A total of 1132 stroke cases and 209 CHD cases, matched 1:1 to controls (n = 1132) for stroke and 1:2 to controls (n = 418) for CHD, were included in the analysis. ResultsWe found no significant association between plasma tea catechin and the incidence of stroke or CHD in either men or women. However, we found that high plasma levels of epigallocatechin gallate (EGCG) were associated with reduced risk of stroke in non-smoking men; the adjusted odds ratio (95% CI) for the highest vs. non-detectable levels was 0.53 (0.29–0.98). The respective OR in male smokers was 1.23 (0.75–2.16). A significant interaction by smoking status was found for the highest vs. non-detected plasma EGCG in relation to stroke (p-for-interaction: p = 0.09). ConclusionsPlasma tea catechin was not associated with reduced risks of either stroke or CHD, while a protective effect of certain tea catechin on stroke risk is suggested for male non-smokers.

Evaluation of plasma antioxidant activity in rats given excess EGCg with reference to endogenous antioxidants concentrations and assay methods

The contribution of (−)-epigallocatechin gallate (EGCg) intake to in vivo antioxidant activity is unclear, even with respect to plasma. In this study, we examined how administration of EGCg contributes to plasma antioxidant activity, relative to its concentration, endogenous antioxidants, and assay methods, namely oxygen radical absorbance capacity (ORAC) and ferric reducing/antioxidant power (FRAP). Administration of EGCg (500 mg/kg) to rats increased plasma EGCg (4μmol/L as free form) and ascorbic acid (1.7-fold), as well as ORAC (1.2-fold) and FRAP (3-fold) values. The increase in plasma ascorbic acid following EGCg administration was accompanied by its relocation from the adrenal glands and lymphocytes into plasma, and was related to the increase in FRAP. Plasma deproteinization and assays in plasma model solutions revealed that protein levels significantly contributed to ORAC values, where <3 μmol/L EGCg in the presence of protein exhibited minimal antioxidant activity, as measured by both FRAP and ORAC. As the concentration of plasma ascorbic acid was not influenced by deproteinization, differences in FRAP values with and without deproteinization were estimated to determine the contribution of enhanced ascorbic acid attributable to EGCg administration. These results will help to understand the points that should be considered when evaluating EGCg antioxidant activity in plasma.

Abstract A20: A phase II randomized, presurgical placebo-controlled trial of polyphenon E in bladder cancer patients to evaluate bladder tissue levels of EGCG and biomarkers of growth and apoptosis

Abstract Introduction: Bladder cancer patients are faced with significant morbidity and mortality due to tumor recurrence and progression and therefore would benefit from an effective chemopreventive strategy. Green tea consumption has been associated with a reduction in bladder cancer risk. Polyphenon E is a green tea polyphenol formulation primarily consisting of epigallocatechin gallate (EGCG) which has been shown in preclinical studies to inhibit growth of bladder cancer. We evaluated the tolerability, tissue accumulation, and biologic effects of polyphenon E in a randomized, double-blind, placebo-controlled phase II preoperative study in patients with bladder cancer. Methods: Patients who had an initial diagnosis or recurring bladder tumor found on diagnostic cystoscopy were randomized in a 1:1:1 ratio to receive 800 mg, 1200 mg or placebo polyphenon E prior to undergoing TURBT or radical cystectomy. The primary objective of the study was to assess the nonmalignant bladder tissue levels of EGCG. Secondary objectives included comparison of EGCG levels in nonmalignant versus malignant tissue within treatment arms; examination of the dose-dependent modulation of surrogate endpoint biomarkers (PCNA, MMP2, Clusterin, VEGF, p27, IGF-1, IGFBP-3) in malignant and nonmalignant bladder tissue; correlation of plasma, urine and tissue levels of EGCG; examination of the levels of other catechins (epicatechin, epicatechin gallate, and epigallocatechin) in plasma, tissue, and urine; metabolism of EGCG in plasma, urine and tissue by COMT and UGT in relation to pharmacogenomic mutations. Results: 31 patients (84% male, 16% female) were randomized with a mean age of 67.2 years. Four patients (13%) were non-compliant and drug administration was interrupted in one other patient (3%), whereas the remainder of patients for which we have reports completed study agent administration (n=24, 77%). The worst adverse event severity was severe (grade 3) for one (3%) patient, moderate for five patients (16%), and mild for eight (26%) patients, whereas no adverse event occurred in 17 (55%) of the patients. Although we found a low rate of detectability in tissue (4/25 with detectable values), tissue levels of EGCG were identified in a dose-dependent fashion in both normal (0.00, 0.50, 1.72 ng/ml, p=0.046) and malignant (0.00, 0.00, 2.54 ng/ml p=0.005) bladder tissue for the placebo, low dose and high dose polyphenon E arms respectively. Plasma EGCG levels (2.94, 78.09, 87.52 ng/ml, p=0.001) and urine EGCG levels (0.00, 2.60, 4.32 ng/ml, p&amp;lt;0.001) were also found to be dose-dependent. Statistically significant dose-dependent downregulation of tissue biomarkers PCNA (0.41, 0.38, 0.35 OD, p=0.016) and clusterin (0.074, 0.061, 0.046 OD, p=0.008) was observed, also accompanied by a nonsignificant reduction in p27 expression (0.36, 0.35, 0.31 OD, p=0.15). No consistent relationship between COMT and UGT pharmogenomic mutational status and EGCG metabolism was observed. Conclusions: We demonstrate in a phase II pilot study tissue accumulation of EGCG in benign and malignant bladder urothelium which follows both plasma and urine levels in a dose-dependent fashion. Furthermore, tissue endpoint biomarkers of proliferation (PCNA) and apoptosis (clusterin) were reduced in a statistically significant dose-dependent fashion. Acknowledging the limitations of this pilot study, we feel these findings indicate polyphenon E administration results in definable tissue accumulation and more importantly desirable biologic activity which warrant further clinical studies assessing the effect of polyphenon E on actual bladder tumor recurrence/progression. Citation Format: Jason R. Gee, Daniel R. Saltzstein, KyungMann Kim, Jill Kolesar, Wei Huang, Tom Havighurst, Barbara W. Wollmer, Jeanne Stublaski, Tracy Downs, Hasan Mukhtar, Margaret House, Howard Parnes, Howard Bailey. A phase II randomized, presurgical placebo-controlled trial of polyphenon E in bladder cancer patients to evaluate bladder tissue levels of EGCG and biomarkers of growth and apoptosis. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr A20.

Food Inhibits the Oral Bioavailability of the Major Green Tea Antioxidant Epigallocatechin Gallate in Humans.

The bioavailability of the most abundant and most active green tea antioxidant, epigallocatechin gallate (EGCG) remains uncertain. Therefore, the systemic absorption of EGCG was tested in healthy fasted humans. It was administered as capsules with water or with a light breakfast, or when incorporated within a strawberry sorbet. The results for plasma EGCG clearly revealed that taking EGCG capsules without food was better; the AUC was 2.7 and 3.9 times higher than when EGCG capsules were taken with a light breakfast (p = 0.044) or with EGCG imbedded in the strawberry sorbet (p = 0.019), respectively. This pattern was also observed for Cmax and Cav. Therefore, ingesting food at the same time as EGCG, whether it was imbedded or not in food, substantially inhibited the absorption of the catechin. As with some types of medications that are affected by food, it appears that EGCG should be taken without food in order to maximise its systemic absorption. Therefore, based on these findings, ingesting EGCG with water on an empty stomach is the most appropriate method for the oral delivery of EGCG in clinical trials where EGCG is to be investigated as a potential bioactive nutraceutical in humans.

A Phase 1 Trial of Daily Oral Green Tea Extract in Asymptomatic, Rai Stage 0–II Patients with Chronic Lymphocytic Leukemia.

BACKGROUND: Green tea has long been touted as a health promoting substance. The active chemical compounds in green tea are called polyphenols or catechins. Epigallocatechin gallate(EGCG) is the major catechin in green tea. We previously reported the in vitro ability of EGCG to induce apoptotic cell death in chronic lymphocytic leukemia(CLL) B-cells in vitro (Blood 104:788). After publication of our findings, clinical activity in individuals using over the counter green tea extracts were reported (Leuk Res 30:707). Based on this information, we opened a phase I/II trial of green tea extracts for patients with asymptomatic, early stage CLL in fall of 2005.METHODS: The purpose of the phase I portion of this trial was to determine the optimal dose of EGCG in the Polyphenon E preparation for chronic daily administration and define tolerability in CLL patients. Previously untreated patients with asymptomatic, Rai stage 0–II CLL not currently meeting National Cancer Institute(NCI) Working Group(WG) Criteria for treatment were eligible for participation. Polyphenon E with a standardized dose of EGCG was obtained from NCI. The phase I portion of the trial was designed with 8 dose levels(range 400–2000 mg orally BID) using the standard 3 patient per dose level design. Patients remained on study up to 6 months. Grade 2 adverse events attributed to study treatment that did not respond to supportive care were considered dose limiting toxicity. The trial was designed to administer Polyphenon E in the fasting state. After accrual to dose levels 1 and 2, the U.S. FDA mandated all U.S. trials of Polyphenon E administer drug in the fed state. Accordingly, drug was administered in the fed state for dose levels 3–8. Trough plasma EGCG levels were measured 1 month after initiation of therapy. Response was classified using the NCI WG Criteria.RESULTS: As of August 2007, 33 patients have been accrued to dose levels 1–8. The maximum tolerated dose(MTD) has not been reached. Side effects have generally been mild. The most common toxicities were nausea(grade 1: 42%; grade 2: 3%), elevation in SGOT (42%; all grade 1), and abdominal pain (36%; all grade 1). To date, no patient has had a sustained 50% reduction in both absolute lymphocyte count (ALC) and lymphadenopathy that would meet the NCI WG criteria for partial response. A majority of patients have had a reduction in ALC(Table). Among the 10 patients who had palpable adenopathy at study enrollment, 7 patients experienced at least a 50% reduction in the sum of the products of all nodal areas at some point during treatment. Trough plasma EGCG levels after 1 month of treatment ranged from 2.93974 ng/mL(median 40.5 ng/mL). Plasma levels did not clearly relate to the degree of reduction in ALC suggesting sensitivity to Polyphenon E may relate more to characteristics of the leukemic clone than plasma EGCG levels.CONCLUSION: Daily oral EGCG in the Polyphenon E preparation was well tolerated by CLL patients in this phase I trial. The MTD has not been reached. As classified by the NCI WG criteria, no partial or complete remissions have been observed to date, however declines in ALC and lymphadenopathy have been observed in the majority of patients. The phase II portion of this trial will open at Mayo Clinic Fall 2007.Best reduction in ALCn% of patientsAt least 10% decline2576%At least 20% decline1442%At least 30% decline824%At least 40% decline412%At least 50% decline26%

Acute EGCG Supplementation Reverses Endothelial Dysfunction in Patients with Coronary Artery Disease

Background: Epidemiological studies demonstrate an inverse relation between dietary flavonoid intake and cardiovascular risk. Recent studies with flavonoid-containing beverages suggest that the benefits of these nutrients may relate, in part, to improved endothelial function.Objective: We hypothesized that dietary supplementation with epigallocatechin gallate (EGCG), a major catechin in tea, would improve endothelial function in humans.Design: We examined the effects of EGCG on endothelial function in a double blind, placebo-controlled, crossover design study. We measured brachial artery flow-mediated dilation by vascular ultrasound at six time points: prior to treatment with EGCG or placebo, two hours after an initial dose of EGCG (300 mg) or placebo, and after two weeks of treatment with EGCG (150 mg twice daily) or placebo. The order of treatments (EGCG or placebo) was randomized and there was a one-week washout period between treatments.Results: A total of 42 subjects completed the study, and brachial artery flow-mediated dilation improved from 7.1 ± 4.1 to 8.6 ± 4.7% two hours after the first dose of 300 mg of EGCG (P = 0.01), but was similar to baseline (7.8 ± 4.2%, P = 0.12) after two weeks of treatment with the final measurements made approximately 14 hours after the last dose. Placebo treatment had no significant effect, and there were no changes in reactive hyperemia or the response to sublingual nitroglycerin. The changes in vascular function paralleled plasma EGCG concentrations, which increased from 2.6 ± 10.9 to 92.8 ± 78.7 ng/ml after acute EGCG (P < 0.001), but were unchanged from baseline after two weeks of treatment (3.4 ± 13.1 ng/ml).Conclusion: EGCG acutely improves endothelial function in humans with coronary artery disease, and may account for a portion of the beneficial effects of flavonoid-rich food on endothelial function.

Safety studies on epigallocatechin gallate (EGCG) preparations. Part 1: Genotoxicity

Public interest in green tea has grown recently due to the potential health benefits from its consumption. Epigallocatechin gallate (EGCG), a principal polyphenolic component of green tea, is considered key to these healthful qualities. Although numerous studies have evaluated the anti-cancer effects of green tea and EGCG, few have examined the safety of EGCG consumption. The genotoxic potential of a concentrated EGCG preparation was tested in Salmonella and L5178Y tk +/− mouse lymphoma cell assays to further define the safety of Teavigo™, a high-concentration EGCG extract of Camellia sinensis leaves produced by the same novel method. No mutagenic activity was detected in the bacterial system; however, a clastogenic ‘trend’ from the formation of hydrogen peroxide was noted in the murine cells. The oral administration of 500, 1000, or 2000 mg EGCG/kg to mice did not induce micronuclei formation in bone marrow cells. Similarly, administering 400, 800, or 1200 mg EGCG/kg/day in their diet for 10 days did not induce bone marrow cell micronuclei and produced plasma EGCG concentrations comparable to those reported in human studies. The intravenous injection of 10, 25 and 50 mg EGCG/kg/day to rats resulted in much higher plasma concentrations and demonstrated an absence of genotoxic effects. From these studies, it is concluded that Teavigo™ (EGCG) is not genotoxic.

Effects of Catechins and Ground Green Tea Drinking on the Susceptibility of Plasma and LDL to the Oxidation In Vitro and Ex Vivo

We investigated the effects of catechins and ground green tea drinking on the susceptibilities of human low density lipoprotein (LDL) and plasma to the oxidation by CuSO4 in vitro and ex vivo. The effects of (-)epicatechin (EC) and (-)epigallocatechin gallate (EGCg) on LDL oxidation in vitro were estimated by measuring the lag time of conjugated diene formation, lipid hydroperoxide and agarose gel electrophoretic mobility. EC and EGCg had antioxidant activities for LDL oxidation, and the antioxidant activity of EGCg to LDL oxidation was stronger than that of EC in vitro. In an ex vivo study, we investigated the effects of ground green tea drinking on LDL and plasma oxidation after the consumption of a cup of green tea (5g). Plasma total catechin contents were increased at 1 and 3h after the oral ingestion, and we detected (-)epigallocatechin (EGC), EC, EGCg and (+)catechin (CA) in plasma. The lag time of conjugated diene formation of plasma was increased in all subjects after consumption of green tea (p<0.028), but the susceptibility of LDL oxidation ex vivo was different among individual subjects. Although the β-carotene, α-tocopherol and uric acid contents in plasma did not change after green tea consumption, ascorbic acid contents in plasma increased at 3h after green tea ingestion. These findings suggest that catechins suppressed the susceptibilities of human LDL to oxidation by CuSO4 in vitro and plasma oxidation ex vivo after ground green tea ingestion.

Catechins Are Bioavailable in Men and Women Drinking Black Tea throughout the Day

Tea consumption has been associated with reduced risk of both cancer and cardiovascular disease in population studies, but clinical data demonstrating bioavailability of the individual catechins and other polyphenolic components of tea are limited. This study assessed the apparent bioavailability of the prominent catechins from black tea in humans drinking tea throughout the day. After 5 d of consuming a low flavonoid diet, subjects drank a black tea preparation containing 15.48, 36.54, 16.74, and 31.14 mg of (-)-epigallocatechin (EGC), (-)-epicatechin (EC), (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG), respectively, at four time points (0, 2, 4 and 6 h). Blood, urine and fecal specimens were collected over a 24- to 72-h period and catechins were quantified by HPLC with coularray detection. Plasma concentrations of EGC, EC and EGCG increased significantly relative to baseline (P < 0.05). Plasma EGC, EC and EGCG peaked after 5 h, whereas ECG peaked at 24 h. Urinary excretion of EGC and EC, which peaked at 5 h, was increased relative to baseline amounts (P < 0.05) and fecal excretion of all four catechins was increased relative to baseline (P < 0.05). Approximately 1.68% of ingested catechins were present in the plasma, urine and feces, and the apparent bioavailability of the gallated catechins was lower than the nongallated forms. Thus, catechins were bioavailable. However, unless they are rapidly metabolized or sequestered, the catechins appeared to be absorbed in amounts that were small relative to intake.