Administration Of Epigallocatechin-3-gallate Research Articles

MiRNA-150-5p associate with antihypertensive effect of epigallocatechin-3-gallate revealed by aorta miRNome analysis of spontaneously hypertensive rat

AimsThe antihypertensive mechanism (s) of the epigallocatechin-3-gallate (EGCG), a major effective component in green tea, might associate with microRNAs (miRNAs). Here, we aimed to investigate which microRNA in aorta of spontaneously hypertensive rats (SHRs) were modulated by administration of EGCG and its mechanism. Main methodsThe pharmacokinetic behaviors of EGCG and epigallocatechin (EGC) in Sprague-Dawley rats were analyzed by HPLC and DRUG AND STATISTICS software. Blood pressure of SHRs was monitored by the tail-cuff method, the miRNomes of aorta from SHRs was analyzed with deep sequencing, and expression of hypertension-associated miRNAs with significant change and their host genes and target genes were validated by real-time PCR and Western blot. Key findingsThe plasma deposition of EGCG and EGC best fitted a mono-compartmental model with maximum plasma concentration post-dose (Cmax, 6.65 vs 4.45 μg/ml) and the corresponding time (Tmax, 15 vs 10 min). Systolic blood pressure (SBP) of SHRs decreased to the lowest point by 34.04 mmHg and recovered by 23.39 mmHg after 15 and 30 min of administration at dose of 300 mg/kg BW EGCG, respectively, and it decreased again at 60 min and recovered at time 2 h. Total 35 upregulated and 18 downregulated miRNAs were identified compared to the control group (p < .01) after EGCG administration. Expression of hypertension-associated miRNA-126a-3p and miRNA-150-5p were further validated. In turn, their host gene and target genes were up-regulated and down-regulated, respectively. SignificanceOur results indicated that miRNA-150-5p might be involved in the antihypertensive effect of EGCG through SP1/AT1R pathway.

EGCG promotes cell growth inhibition and reprograms mesenchymal‐epithelial transition by restoring CCN5/WISP2 in triple negative breast cancer cells in vitro and in vivo

Background and ObjectiveCCN5/WISP‐2, a matricellular secretory protein that is localized in both cytoplasm and nucleus, is mainly expressed in luminal cells rather than basal cell types in breast cancer tumors. Endogenous CCN5 plays critical role in promoting growth arrest and reprograming Mesenchymal to Epithelial Transition(MET), inhibition of migration and invasion, overall inducing the invasive to non‐invasive phenotypes. Thus, we hypothesize that targeting endogenous CCN5 restoration in Triple‐negative‐breast cancer (TNBC) cells could be an ideal strategy to prevent the progression of TNBC. To test the hypothesis, we set out to identify a molecule that has the capability to restore CCN5 in TNBC cells. Here we report that CCN5, which is normally absent in TNBC cells can be restored by a common dietary supplement epigallocatechin‐3‐gallate (EGCG), an ester of epigallocatechin and gallic acid, and is a type of catechin, to promote growth arrest and reverse EMT.MethodsEffect of EGCG on breast cancer cells were characterized by in vitro protein and gene expression profilings, cytotoxic assays, colony formation assays, migration assays, anchorage independent growth assays. In vivo effect of EGCG on tumorigenesis was investigated in xenograft model of immunosuppressive mice.Result and ConclusionEGCG treatment in breast cancer cells significantly elevated and restored CCN5 expression in TNBC cells along with inhibition of cell proliferation, migration and colony formation and induction of apoptosis. Reprogramming of mesenchymal to epithelial transition(MET) was also observed in EGCG‐treated TNBC cells. Oral administration of EGCG resulted in drastic inhibition of tumor growth and propagation in immunosuppressive mouse xenografts of MDA‐MB‐231 cells, along with restoration of CCN5 expression. Altogether, these studies clearly indicate that EGCG is an ideal molecule to restore CCN5 in TNBC cells in preventing the TNBC growth, progression and possibly make these cells susceptible to anti‐estrogen treatment, as restoration of CCN5 causes estrogen receptor(ER)‐α in TNBC cells. Moreover, it is reasonable to speculate that the CCN5 pathways probably play an important part in the anti‐tumorigenic role of EGCG in TNBC cells.Support or Funding InformationSupported by Midwest Biomedical Research Foundation and VA Merit Grant.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

(-)-Epigallocatechin-3-Gallate Ameliorates Atherosclerosis and Modulates Hepatic Lipid Metabolic Gene Expression in Apolipoprotein E Knockout Mice: Involvement of TTC39B.

Background: Aberrant chronic inflammation and excess accumulation of lipids play a pivotal role in the occurrence and progression of atherosclerosis. (–)-Epigallocatechin-3-gallate (EGCG), the major catechins in green tea, displayed anti-atherosclerotic properties in vivo and in vitro. However, the effects and underlying mechanism of EGCG on atherosclerosis remain unclear.Methods: Male apolipoprotein E-knockout (ApoE-/-) mice (7 weeks old) fed with high-fat diet (HFD) were treated with normal saline or EGCG (40 mg/kg/d, i.g.) for 18 weeks. Atherosclerotic plaque and liver lipid accumulation were measured by Oil Red staining. Plasma lipids and cytokines were detected using commercial kits. The expression of protein and mRNA was analyzed by western blot and quantitative real-time reverse transcription-polymerase chain reaction, respectively.Results: EGCG administration markedly attenuated atherosclerotic plaque formation in HFD-fed ApoE-/- mice, which were accompanied by increased plasma interleukin-10 (IL-10) level and decreased plasma IL-6 and tumor necrosis factor-α (TNF-α) levels. In addition, EGCG modulated high-fat-induced dyslipidemia, evidencing by decreased total cholesterol (TC) and low-density lipoprotein levels and increased high-density lipoprotein level. Meanwhile, EGCG treatment alleviated high-fat-mediated liver lipid accumulation and decreased liver TC and triglyceride. Mechanistically, EGCG significantly modulated high-fat-induced hepatic tetratricopeptide repeat domain protein 39B (TTC39B) expression and its related genes (Lxrβ, Abcg5, Abcg8, Abca1, Srebf1, Scd1, Scd2, Fas, Elovl5, Mylip) expression in liver from ApoE-/- mice. Notably, EGCG remarkably induced hepatic liver X receptor α (LXRα) and LXRβ expression and inhibited both precursor and mature sterol regulatory element binding transcription factor-1 (SREBP-1) expression.Conclusion: Taken together, our data for the first time suggested that TTC39B was involved in EGCG-mediated anti-atherosclerotic effects through modulation of LXR/SREBP-1 pathway.

Ameliorative Effect of Epigallocatechin Gallate on Cardiac Hypertrophy and Fibrosis in Aged Rats.

The objective of the present study is to evaluate the effect of epigallocatechin gallate (EGCG) on aging-mediated cardiac hypertrophy, fibrosis, and apoptosis. The Wistar albino rats were divided into 4 groups (n = 18). Group I: young (3 months), group II: aged (24-26 months), group III: aged + EGCG (200 mg/kg for 30 days), and group IV: young + EGCG. At the end of 30 days, EGCG administration to the aged animals showed significant (P < 0.001) reduction of low-density lipoprotein, very low-density lipoprotein, triglyceride, total cholesterol with concomitant increase of high-density lipoprotein (P < 0.001) when compared with aged rats. Increased (P < 0.001) heart volume, weight with concomitant increase of left ventricular wall thickness, and reduced ventricular cavity were observed in aged rats supplemented with EGCG compared with aged animals. Histology and histomorphometry study of aged animals treated with EGCG showed marked increases in the diameter and volume of cardiomyocytes with concomitant reduction of numerical density when compared with aged animals. Reduced reactive oxygen species (P < 0.001) production with association of increased antioxidant defense system (P < 0.001) in aged hearts supplemented with EGCG when compared with aged animals. TUNEL staining and fibrosis showed a marked increase in apoptotic cell death (P < 0.001) and collagen deposition (P < 0.001) in aged animals treated with EGCG when compared with aged animals. Aged animals treated with EGCG showed a marked increase in protein expression of TGFβ, TNFα, and nuclear factor kappa B (NF-κB) and significant (P < 0.001) alteration in the gene expression of TGFβ, TNFα, NF-κB, α-SMA, and Nrf2 when compared with aged animals. Taken together, it is evident that EGCG may potentially inhibit aging-induced cardiac hypertrophy, fibrosis, and apoptosis, thereby preserving cardiac function. The proposed mechanism would be inhibition of reactive oxygen species-dependent activation of TGFβ1, TNFα, and NF-κB signaling pathway. Hence, the present study suggests that EGCG can be useful to fight against aging-induced cardiac hypertrophy, fibrosis, and apoptosis.

Epigallocatechin gallate induces GLUT4 translocation in skeletal muscle through both PI3K- and AMPK-dependent pathways.

Our previous report demonstrated that epigallocatechin gallate (EGCg) promotes translocation of glucose transporter 4 (GLUT4) in skeletal muscle. In this study, we investigated the molecular mechanism of GLUT4 translocation by EGCg at the physiological concentration range. In L6 cells, EGCg induced phosphorylation of phosphatidylinositide 3'-kinase (PI3K) and downstream protein kinase C (PKC) λ/ξ without affecting the phosphorylation of insulin receptor and Akt. EGCg-induced GLUT4 translocation was suppressed by RNA interference-mediated knockdown of PI3K and treatment with PKC inhibitor Go6983. Moreover, EGCg increased Rac1 activity and actin remodelling as downstream events of PKCλ/ξ. These results indicate that EGCg induced GLUT4 translocation through a PI3K-dependent pathway, but its mode of action differed from that of insulin. EGCg also induced GLUT4 translocation through a 5'-adenosine monophosphate-activated protein kinase (AMPK)-dependent pathway. 67 kDa laminin receptor, which is a target molecule of EGCg, was not involved in EGCg-induced glucose uptake in L6 cells. The oral administration of EGCg suppressed postprandial hyperglycaemia accompanied by GLUT4 translocation through both PI3K- and AMPK-dependent pathways, and promoted glycogen accumulation in skeletal muscle of ICR mice. EGCg promotes GLUT4 translocation through both PI3K- and AMPK-dependent pathways and glycogen accumulation in skeletal muscle.

Epigallocatechin-3-gallate protects against diabetic cardiomyopathy through modulating the cardiometabolic risk factors, oxidative stress, inflammation, cell death and fibrosis in streptozotocin-nicotinamide-induced diabetic rats

The potential protective effect of epigallocatechin-3-gallate (EGCG) on type 2 diabetes-induced heart injury was investigated. A rat model of diabetes was achieved by injection of nicotinamide (100mg/kg, i.p), 20min before the administration of streptozotocin (55mg/kg, i.p.). After confirmation of diabetes, EGCG (2mg/kg, p.o.) was administrated on alternate days for one month. Treatment of diabetic rats with EGCG showed a remarkable reduction in glucose, glycosylated hemoglobin, HOMA-IR and lipid profile levels with an elevation in insulin levels, indicating its antihyperglycemic and antidyslipidemic actions. EGCG treatment also suppressed the increase in the levels of superoxide, 4-hydroxynonenal and protein carbonyl, whereas it increased the content of glutathione and the activities of superoxide dismutase and catalase in heart of diabetic rats, indicating its antioxidant capacity. In addition, EGCG improved heart function of diabetic rats as evidenced by a remarkable reduction in troponin T level and creatine kinase-MB, lactate dehydrogenase and aspartate aminotransferase activities in the serum. Oral administration of EGCG for one month after diabetes induction significantly protected the increase in serum levels of pro-inflammatory cytokines (IL-1 β, IL-6 and TNF-α) and adhesion molecules (ICAM-1 and VCAM-1), suggesting its anti-inflammatory potential. Furthermore, EGCG hampered the mitochondrial apoptotic pathway through increasing Bcl-2 level and decreasing p53, Bax, cytochrome c and caspase-3 and 9 levels in hearts of diabetic rats, indicating its anti-apoptotic action. Diabetic rats treated with EGCG also exhibited decreased level of DNA damage in the myocardium. The histological examinations indicated the cardioprotective effect of EGCG against harmful impact of diabetes. Therefore, these findings suggest that EGCG has a protective effect on the heart affected by type 2 diabetes and recommend it as a complementary supplement for diabetic patients.

Protective effects of a green tea polyphenol, epigallocatechin-3-gallate, against sevoflurane-induced neuronal apoptosis involve regulation of CREB/BDNF/TrkB and PI3K/Akt/mTOR signalling pathways in neonatal mice.

Epigallocatechin-3-gallate (EGCG), a polyphenol in green tea, is an effective antioxidant and possesses neuroprotective effects. Brain-derived neurotrophic factor (BDNF) and cyclic AMP response element-binding protein (CREB) are crucial for neurogenesis and synaptic plasticity. In this study, we aimed to assess the protective effects of EGCG against sevoflurane-induced neurotoxicity in neonatal mice. Distinct groups of C57BL/6 mice were given EGCG (25, 50, or 75 mg/kg body weight) from postnatal day 3 (P3) to P21 and were subjected to sevoflurane (3%; 6 h) exposure on P7. EGCG significantly inhibited sevoflurane-induced neuroapoptosis as determined by Fluoro-Jade B staining and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL). Increased levels of cleaved caspase-3, downregulated Bad and Bax, and significantly enhanced Bcl-2, Bcl-xL, xIAP, c-IAP-1, and survivin expression were observed. EGCG induced activation of the PI3K/Akt pathway as evidenced by increased Akt, phospho-Akt, GSK-3β, phospho-GSK-3β, and mTORc1 levels. Sevoflurane-mediated downregulation of cAMP/CREB and BDNF/TrkB signalling was inhibited by EGCG. Reverse transcription PCR analysis revealed enhanced BDNF and TrkB mRNA levels upon EGCG administration. Improved performance of mice in Morris water maze tests suggested enhanced learning and memory. The study indicates that EGCG was able to effectively inhibit sevoflurane-induced neurodegeneration and improve learning and memory retention of mice via activation of CREB/BDNF/TrkB-PI3K/Akt signalling.

(-)-Epigallocatechin-3-gallate ameliorates memory impairment and rescues the abnormal synaptic protein levels in the frontal cortex and hippocampus in a mouse model of Alzheimer's disease.

(-)-Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenolic extract in green tea and it has attracted increasing attention for its multiple bioactive effects. However, the mechanisms by which EGCG exerts its neuroprotective actions in Alzheimer's disease (AD) are presently lacking. In the present study, a sporadic AD transgenic mouse model known as senescence-accelerated mouse prone 8 (SAMP8) was used to investigate whether oral administration of EGCG could improve recognition and memory function through reduction of amyloid β (Aβ) and tau hyperphosphorylation. We also investigated the effects of chronic EGCG treatment on the synaptic dysfunction in the frontal cortex (FC) and the hippocampus (Hip) of AD mice. The results showed that long-term oral consumption of EGCG at a relatively high dose (15 mg/kg) improved memory function in SAMP8 mice in the Y-maze and Morris water maze. The levels of Aβ1-42 and BACE-1 in FC and Hip were significantly reduced by EGCG treatment. EGCG treatment also prevented the hyperphosphorylation of tau and reversed the decreased synaptic protein marker synaptophysin and postsynaptic density protein 95 in FC and Hip of SAMP8 mice. The present study suggests that long-term oral consumption of EGCG ameliorates impairments in spatial learning and memory and rescues the reduction in synaptic proteins observed in an AD mouse model. Thus, EGCG may represent a novel candidate agent for the treatment of neurodegenerative diseases.

Anti-inflammatory effect of epigallocatechin gallate in a mouse model of ovalbumin-induced allergic rhinitis

Currently, a variety of studies have demonstrated that green tea has anti-allergic properties, and the major polyphenolic compound, epigallocatechin gallate (EGCG), plays a significant role. Some research indicates that EGCG reduces the production and expression of allergy-related substances. Therefore, EGCG has a potential effect of reducing allergic rhinitis (AR). In this study, the effect of EGCG on allergic rhinitis in an ovalbumin (OVA)-induced mouse model was investigated. After administration of EGCG, the number of sneezes and the occurrence of nasal rubbing were significantly decreased, the concentrations of immunoglobulin E (IgE) and histamine were suppressed in AR mouse serum, the levels of interleukin (IL)-1β, IL-4, and IL-6 were reduced in AR mice nasal lavage fluid (NLF), and the nasal mucosa mRNA and protein expression of cyclooxygenase 2 (COX-2), IL-1β, IL-4, and IL-6 were inhibited. The data indicate that EGCG has a beneficial effect of reducing allergic rhinitis.

Green tea epigallocatechin gallate enhances cardiac function restoration through survival signaling expression in diabetes mellitus rats with autologous adipose tissue-derived stem cells.

The present study tests a hypothesis that cardioprotective effects mediated by autologous adipose-derived stem cells (ADSC) in rats afflicted with insulin-dependent diabetes mellitus (IDDM) may be synergistically enhanced by oral treatment with green tea epigallocatechin gallate (EGCG). Wistar rats were divided into sham, DM, DM+ADSC (autologous transplanted 1 × 106 cells per rat), and DM+ADSC+E (E, green tea oral administration EGCG). Heart tissues were isolated from all rats, and investigations were performed after 2-mo treatment. In the sham, DM, and DM+ADSC groups, we found that DM induced cardiac dysfunction (sham and DM) and autologous ADSC transplantation could partially recover cardiac functions (DM and DM+ADSC) in DM rats. Compared with DM+ADSC, significant improvement in cardiac functions can be observed in DM+ADSC+E in echocardiographic data, histological observations, and even cellular protein expression. Oral green tea EGCG administration and autologous ADSC transplantation show synergistically beneficial effects on diabetic cardiac myopathy in DM rats.NEW & NOTEWORTHY Cardiomyopathy can be induced in rats with diabetes mellitus (DM). Heart function can be restored in DM rats with adipose-derived stem cell treatment. Oral epigallocatechin gallate (EGCG) administration synergistically enhances cardiac function in DM rats with stem cell treatment. The EGCG and stem cell treatment cross-effect occurs via survival protein expression.

Epigallocatechin-3-gallate ameliorates intrahepatic cholestasis of pregnancy by inhibiting matrix metalloproteinase-2 and matrix metalloproteinase-9.

Matrix metalloproteinase (MMP)-2 and matrix metalloproteinase-9 are involved in many illnesses affecting pregnant women, including intrahepatic cholestasis of pregnancy (ICP), a serious liver abnormality during pregnancy. Epigallocatechin-3-gallate (EGCG) has been widely reported to inhibit activities of MMP-2 and MMP-9. We aimed to investigate the role of EGCG in ameliorating ICP symptoms in a rat model. Using 17α-ethinylestradiol to induce ICP in pregnant rats, we investigated the efficacy of EGCG administration on ICP symptoms, including bile flow rate, total bile acids (TBA) and MMP-2 and MMP-9 activities. Correlation study was conducted among levels of the two MMPs with other ICP symptoms. In ICP rats, activities of both MMP-2 and MMP-9 were significantly elevated. EGCG administration could inhibit the upregulation of MMP-2 and MMP-9 post-transcriptionally. Furthermore, EGCG ameliorated ICP symptoms, as evidenced by restored bile flow rate and TBA, showing efficient treatment outcomes. At last, levels of TBA and the two MMPs were found to be strongly correlated. Our study demonstrates that, for the first time, the efficacy of EGCG in ameliorating ICP symptoms by inhibiting both MMP-2 and MMP-9, which supports its potential as a novel drug in ameliorating ICP.

Tea-induced improvement of endothelial function in humans: No role for epigallocatechin gallate (EGCG)

Consumption of tea is inversely associated with cardiovascular diseases. However, the active compound(s) responsible for the protective effects of tea are unknown. Although many favorable cardiovascular effects in vitro are mediated by epigallocatechin gallate (EGCG), its contribution to the beneficial effects of tea in vivo remains unresolved. In a randomised crossover study, a single dose of 200 mg EGCG was applied in three different formulas (as green tea beverage, green tea extract (GTE), and isolated EGCG) to 50 healthy men. Flow-mediated dilation (FMD) and endothelial-independent nitro-mediated dilation (NMD) was measured before and two hours after ingestion. Plasma levels of tea compounds were determined after each intervention and correlated with FMD. FMD significantly improved after consumption of green tea containing 200 mg EGCG (p < 0.01). However, GTE and EGCG had no significant effect on FMD. NMD did not significantly differ between interventions. EGCG plasma levels were highest after administration of EGCG and lowest after consumption of green tea. Plasma levels of caffeine increased after green tea consumption. The results show that EGCG is most likely not involved in improvement of flow-mediated dilation by green tea. Instead, other tea compounds, metabolites or combinations thereof may play a role.

Catechins activate muscle stem cells by Myf5 induction and stimulate muscle regeneration

Muscle weakness is one of the most common symptoms in aged individuals and increases risk of mortality. Thus, maintenance of muscle mass is important for inhibiting aging. In this study, we investigated the effect of catechins, polyphenol compounds in green tea, on muscle regeneration. We found that (−)-epicatechin gallate (ECG) and (−)-epigallocatechin-3-gallate (EGCG) activate satellite cells by induction of Myf5 transcription factors. For satellite cell activation, Akt kinase was significantly induced after ECG treatment and ECG-induced satellite cell activation was blocked in the presence of Akt inhibitor. ECG also promotes myogenic differentiation through the induction of myogenic markers, including Myogenin and Muscle creatine kinase (MCK), in satellite and C2C12 myoblast cells. Finally, EGCG administration to mice significantly increased muscle fiber size for regeneration. Taken together, the results suggest that catechins stimulate muscle stem cell activation and differentiation for muscle regeneration.

EGCG ameliorates diet-induced metabolic syndrome associating with the circadian clock

In response to the daily light-dark (LD) cycle, organisms on Earth have evolved with the approximately 24-h endogenous oscillations to coordinate behavioral and physiological processes, including feeding, sleep, and metabolism homeostasis. Circadian desynchrony triggered by an energy-dense diet rich in fats and fructose is intimately connected with a series of metabolic disorders. Previous studies revealed that (−)-Epigallocatechin-3-gallate (EGCG) could mitigate metabolic misalignment; however, only a few reports have focused on its potential effect on directly manipulating circadian rhythms to ameliorate metabolic syndrome. Our goal was to investigate the regulating effect of EGCG treatment on metabolic misalignment triggered by a high-fat and high-fructose diet (HFFD) associating with the circadian clock. Our results indicated that HFFD treatment partially exhibited poor circadian oscillations of the core clock gene and the clock-controlled gene in the liver and fat relative to the control group. EGCG administration may ameliorate the diet-dependent decline in circadian function by controlling the Sirt1-PGC1αloop, implying the existence of an EGCG-entrainable oscillator. Subsequently, reducing fatty acid synthesis and elevating β-oxidation in the liver coupled with the increasing brown adipose tissue (BAT) energy expenditure observed in the EGCG group of mice prevented the adipocyte hypertrophy and fat accumulations common to BAT and white adipose tissue (WAT) derived from the HFFD mice. This study is the first to provide compelling evidences that EGCG may ameliorate diet-induced metabolic misalignment by regulating the rhythmic expression of the circadian clock genes in the liver and fat.

Epigallocatechin gallate attenuates overload‑induced cardiac ECM remodeling via restoring T cell homeostasis.

It has previously been demonstrated that Epigallocatechin gallate(EGCG) has regulatory effects on cellular immunity. The present study explored whether EGCG inhibits the overload‑induced cardiac extracellular matrix(ECM) remodeling through targeting the balance of T cell subpopulations. Sprague‑Dawley rats were subjected to either transverse aortic constriction(TAC) or sham operation. TAC rats were treated with EGCG or valsartan(Val) for 6weeks. The administration of EGCG or Val ameliorated the overproduction of cardiac collagen, inhibited matrix metalloproteinase (MMP) activity, decreased the expression of tissue inhibitor of MMP‑2, atrial natriuretic peptide and brain natriuretic peptide. EGCG regulated the population of effector T cells and naïve T cells, restored the balance of T helper (Th) cell 17/regulatory T cells, via modulating the downstream regulator signal transducer and activator of transcription (STAT3) and STAT5. Furthermore, the ratio of interferon‑γ/interleukin (IL)‑10 which indicates the balance of Th1/Th2, was restored by the treatments at varying degrees. EGCG and Val administration rescued IL‑7 production, and decreased the level of IL‑15 in TAC rats. EGCG has positive therapeutic potential in inhibiting cardiac ECM remodeling. Regulation of the balance of T lymphocyte subsets may be one of the underlying mechanisms responsible for this effect.

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.

Involvement of PKCα and ERK1/2 signaling pathways in EGCG’s protection against stress-induced neural injuries in Wistar rats

Stress-induced neural injuries are closely linked to the pathogenesis of various neuropsychiatric disorders and psychosomatic diseases. We and others have previously demonstrated certain protective effects of epigallocatechin-3-gallate (EGCG) in stress-induced cerebral impairments, but the underlying protective mechanisms still remain poorly elucidated. Here we provide evidence to support the possible involvement of PKCα and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathways in EGCG-mediated protection against restraint stress-induced neural injuries in rats. In both open-field and step-through behavioral tests, the restraint stress-induced neuronal impairments were significantly ameliorated by administration of EGCG or green tea polyphenols (GTPs), which was associated with a partial restoration of normal plasma glucocorticoid, dopamine and serotonin levels. Furthermore, the stress-induced decrease of PKCα and ERK1/2 expression and phosphorylation was significantly attenuated by EGCG and to a less extent by GTP administration. Additionally, EGCG supplementation restored the production of adenosine triphosphate (ATP) and the expression of a key regulator of cellular energy metabolism, the peroxisome proliferators-activated receptor-γ coactivator-1α (PGC-1α), in stressed animals. In conclusion, PKCα and ERK1/2 signaling pathways as well as PGC-1α-mediated ATP production might be involved in EGCG-mediated protection against stress-induced neural injuries.

Nephro-toxic effects of intraperitoneally injected EGCG in diabetic mice: involvement of oxidative stress, inflammation and apoptosis

Epigallocatechin gallate (EGCG) has been studied for its beneficial effects. However, some case reports have associated EGCG supplementation with hepato-toxicity. In the present study, we investigated the possible nephro-toxic effects of EGCG in diabetic mice. Streptozotocin (150 mg/kg, i.p.) was injected in mice for diabetes induction. EGCG (100 mg/kg/day, i.p.) was then given for 4 days. The administration of EGCG to diabetic mice caused 60% mortality with no death recorded in other groups. Blood samples were collected for estimation of serum cystatin C, neutrophil gelatinase-associated lipocalin and blood urea nitrogen. Animals were then sacrificed and kidneys were rapidly excised for estimation of oxidative stress markers (NADPH oxidase, reduced glutathione, total antioxidant capacity, nuclear factor erythroid 2-related factor 2, heat shock protein 90, hemeoxygenase-1), as well as inflammatory markers (nuclear factor kappa-B and tumor necrosis factor-α). Administration of EGCG to diabetic mice showed significant elevation in serum cystatin C and neutrophil gelatinase-associated lipocalin, marked increase in oxidative stress and inflammatory states in addition to marked over expression of active caspase-3. Histopathological examination confirmed EGCG induced renal damage in diabetic mice. In conclusion, despite of its well known favorable effects, EGCG could paradoxically exhibit nephro-toxic effect in the presence of diabetes.

Mitochondrial DNA-Induced Inflammatory Responses and Lung Injury in Thermal Injury Rat Model: Protective Effect of Epigallocatechin Gallate.

Lungs are easily damaged by the inflammatory responses induced after extensive burns. The aim here was to investigate the protective role of epigallocatechin gallate (EGCG) in mitochondrial DNA (mtDNA)-mediated inflammatory responses and acute respiratory distress syndrome (ARDS) in a rat model of thermal injury. Male Sprague-Dawley rats were randomly assigned to five groups. In the first experiment, a full-thickness thermal injury or control procedure, covering 30% of the TBSA, was inflicted on three groups designated as the thermal injury, EGCG, and sham control groups. In the second experiment, another two groups were established by transfusion with either mtDNA (mtDNA group) or phosphate-buffered saline (phosphate-buffered saline group). Blood samples and lung tissue from all five groups were collected and the plasma concentrations of mtDNA and inflammatory mediators were measured. Bronchoalveolar lavage fluid was collected and histological analysis of the lung tissue was performed to evaluate the severity of ARDS. Significant increases in mtDNA and inflammatory mediator plasma concentrations were seen in the thermal injury and EGCG groups when compared with controls (P < .05). The plasma concentrations of mtDNA and inflammatory mediators were significantly decreased after the administration of EGCG (P < .05). EGCG also significantly reduced the severity of acute lung injury (P < .05). Intravenous administration of mtDNA significantly increased concentrations of inflammatory mediators and caused severe ARDS (P < .05). Our results suggest that mtDNA is important for thermal injury-induced inflammation and associated ARDS. EGCG possesses anti-inflammatory and lung-protective properties, and might act by limiting mtDNA release after thermal injury.

Epigallocatechin Gallate Extends Therapeutic Window of Recombinant Tissue Plasminogen Activator Treatment for Brain Ischemic Stroke: A Randomized Double-Blind and Placebo-Controlled Trial.

Recombinant tissue plasminogen activator (rt-PA) is a safe and effective treatment for acute brain ischemia stroke, albeit with a narrow therapeutic window. We aimed to assess the effect of epigallocatechin gallate (EGCG) in extending the rt-PA treatment window in this clinical trial among stroke patients. Patients were randomly assigned according to their onset-to-treatment time (OTT) and were then treated with rt-PA simultaneously with EGCG or placebo. Treatment outcome was assessed by the National Institutes of Health stroke scale (NIHSS) and plasma levels of matrix metalloproteinases (MMP)-2 and 9. Administration of EGCG significantly improved treatment outcomes of patients in the delayed OTT strata, as evidenced by improved NIHSS scores. This improved treatment outcome was likely attributed to reduction in plasma levels of both MMP-2 and 9, as indicated by strong linear correlations between both MMPs and NIHSS scores in all patients. Epigallocatechin gallate could potentially be used as a supplement of traditional rt-PA treatment among stroke patients, particularly those with delayed OTT, to extend the otherwise narrow therapeutic window and improve the outcome in late stroke treatment.