Activity Of Epigallocatechin-3-gallate Research Articles

Protective Effects of Epigallocatechin Gallate (EGCG) on Endometrial, Breast, and Ovarian Cancers.

Green tea and its major bioactive component, (−)-epigallocatechin gallate (EGCG), possess diverse biological properties, particularly antiproliferation, antimetastasis, and apoptosis induction. Many studies have widely investigated the anticancer and synergistic effects of EGCG due to the side effects of conventional cytotoxic agents. This review summarizes recent knowledge of underlying mechanisms of EGCG on protective roles for endometrial, breast, and ovarian cancers based on both in vitro and in vivo animal studies. EGCG has the ability to regulate many pathways, including the activation of nuclear factor erythroid 2-related factor 2 (Nrf2), inhibition of nuclear factor-κB (NF-κB), and protection against epithelial–mesenchymal transition (EMT). EGCG has also been found to interact with DNA methyltransferases (DNMTs) and histone deacetylases (HDACs), which affect epigenetic modifications. Finally, the action of EGCG may exert a suppressive effect on gynecological cancers and have beneficial effects on auxiliary therapies for known drugs. Thus, future clinical intervention studies with EGCG will be necessary to more and clear evidence for the benefit to these cancers.

New perspective to improve dentin–adhesive interface stability by using dimethyl sulfoxide wet-bonding and epigallocatechin-3-gallate

ObjectivesTo determine whether dentin–adhesive interface stability would be improved by dimethyl sulfoxide (DMSO) wet-bonding and epigallocatechin-3-gallate (EGCG). MethodsEtched dentin surfaces from sound third molars were randomly assigned to five groups according to different pretreatments: group 1, water wet-bonding (WWB); group 2, 50% (v/v) DMSO wet-bonding (DWB); groups 3–5, 0.01, 0.1, and 1 wt% EGCG-incorporated 50% (v/v) DMSO wet-bonding (0.01%, 0.1%, and 1%EGCG/DWB). Singlebond universal adhesive was applied to the pretreated dentin surfaces, and composite buildups were constructed. Microtensile bond strength (μTBS) and interfacial nanoleakage were respectively examined after 24 h water storage or 1-month collagenase ageing. In situ zymography andStreptococcus mutans (S. mutans) biofilm formation were also investigated. ResultsAfter collagenase ageing, μTBS of groups 4 (0.1%EGCG/DWB) and 5 (1%EGCG/DWB) did not decrease (p > 0.05) and was higher than that of the other three groups (p < 0.05). Nanoleakage expression of groups 4 and 5 was less than that of the other three groups (p < 0.05), regardless of collagenase ageing. Metalloproteinase activities within the hybrid layer in groups 4 and 5 were suppressed. Furthermore, pretreatment with 1%EGCG/DWB (group 5) efficiently inhibited S. mutans biofilm formation along the dentin–adhesive interface. SignificanceThis study suggested that the synergistic action of DMSO wet-bonding and EGCG can effectively improve dentin–adhesive interface stability. This strategy provides clinicians with promising benefits to achieve desirable dentin bonding performance and to prevent secondary caries, thereby extending the longevity of adhesive restorations.

Prooxidant Effects of Epigallocatechin-3-Gallate in Health Benefits and Potential Adverse Effect.

Epigallocatechin-3-gallate (EGCG) is the major polyphenolic compound present in green tea and is generally regarded as an effective antioxidant. However, its chemical reactivity makes it susceptible to generate reactive oxygen species (ROS) via autooxidation and exhibit prooxidant effects. The prooxidant actions of EGCG could play a dual role, being both beneficial and harmful. This review summarized recent research progress on (1) the anticancer, antiobesity, and antibacterial effects of EGCG and (2) the possible toxicity of EGCG. The major focus is on the involvement of prooxidant effects of EGCG and their effective doses used. Considering dosage is a crucial factor in the prooxidant effects of EGCG; further studies are required to find the appropriate dose at which EGCG could bring more health benefits with lower toxicity.

The Intrinsic Virtues of EGCG, an Extremely Good Cell Guardian, on Prevention and Treatment of Diabesity Complications.

The pandemic proportion of diabesity—a combination of obesity and diabetes—sets a worldwide health issue. Experimental and clinical studies have progressively reinforced the pioneering epidemiological observation of an inverse relationship between consumption of polyphenol-rich nutraceutical agents and mortality from cardiovascular and metabolic diseases. With chemical identification of epigallocatechin-3-gallate (EGCG) as the most abundant catechin of green tea, a number of cellular and molecular mechanisms underlying the activities of this unique catechin have been proposed. Favorable effects of EGCG have been initially attributed to its scavenging effects on free radicals, inhibition of ROS-generating mechanisms and upregulation of antioxidant enzymes. Biologic actions of EGCG are concentration-dependent and under certain conditions EGCG may exert pro-oxidant activities, including generation of free radicals. The discovery of 67-kDa laminin as potential EGCG membrane target has broaden the likelihood that EGCG may function not only because of its highly reactive nature, but also via receptor-mediated activation of multiple signaling pathways involved in cell proliferation, angiogenesis and apoptosis. Finally, by acting as epigenetic modulator of DNA methylation and chromatin remodeling, EGCG may alter gene expression and modify miRNA activities. Despite unceasing research providing detailed insights, ECGC composite activities are still not completely understood. This review summarizes the most recent evidence on molecular mechanisms by which EGCG may activate signal transduction pathways, regulate transcription factors or promote epigenetic changes that may contribute to prevent pathologic processes involved in diabesity and its cardiovascular complications.

Enhancement of the permeability and activities of epigallocatechin gallate by quaternary ammonium chitosan/fucoidan nanoparticles

Epigallocatechin gallate (EGCG) has many biological functions; however, the use of EGCG in biomedical and food industries was limited due to its poor oral absorption and high susceptibility to degradation. In this study, a mucoadhesive quaternary chitosan was synthesized and combined with fucoidan (FD) (or depolymerized lower molecular weight fucoidan, LMWF) to prepare EGCG-loaded nanoparticles, which extended EGCG release over 300 min and enhanced the transepithelial permeation of EGCG using Caco-2 cells as a model for intestinal absorption. The nanoparticls protected EGCG against degradation in phosphate buffer (pH 6.8) and the remaining EGCG was 1.7-folds higher than the control (EGCG alone). The additive effects of EGCG combined with FD or LMWF in the nanoparticles increased the DPPH radical scavenging activity and the enzyme inhibitory activity against α-amylase (2.82–4.92 fold increase) and α-glucosidase (1.35–1.67 fold increase), while quaternary chitosan helped to enhance the antibacterial effect of EGCG.

Beneficial impact of epigallocatechingallate on LDL-C through PCSK9/LDLR pathway by blocking HNF1\u03b1 and activating FoxO3a

BackgroundGreen tea drinking has been proven to lower lipid and exert cardiovascular protection, while the potential mechanism has not been fully determined. This study was to investigate whether the beneficial impact of epigallocatechingallate (EGCG), a type of catechin in green tea on lipids is associated with proprotein convertase subtilisin/kexin type 9 (PCSK9) pathways.MethodsWe studied the effects and underlying molecular mechanism of EGCG or green tea on regulating cholesterol from human, animal and in vitro.ResultsIn the age- and gender-matched case control observation, we found that individuals with frequent tea consumption (n = 224) had the lower plasma PCSK9 and low density lipoprotein cholesterol (LDL-C) levels compared with ones without tea consumption (n = 224, p < 0.05). In the high fat diet (HFD) fed rats, EGCG administration significantly lowered circulating PCSK9 concentration and liver PCSK9 expression, along with up-regulated LDL receptor (LDLR) expression but decreased level of LDL-C. In hepatic cell study, similar results were obtained regarding the impact of EGCG on LDLR and PCSK9 expression. The assay transposase-accessible chromatic with high-throughput sequencing (ATAC-seq) and subsequent results suggested that two transcription factors, hepatocyte nuclear factor-1α (HNF-1α) and forkhead box class O (FoxO) 3a involved in inhibitory action of EGCG on PCSK9 expression.ConclusionsThe present study demonstrates that EGCG suppresses PCSK9 production by promoting nuclear FoxO3a, and reducing nuclear HNF1α, resulting in up-regulated LDLR expression and LDL uptake in hepatocytes. Thereby inhibiting liver and circulating PCSK9 levels, and ultimately lowering LDL-C levels.

Mechanistic Insights into Zika Virus NS3 Helicase Inhibition by Epigallocatechin-3-Gallate.

Since 2007, repeated outbreaks of Zika virus (ZIKV) have affected millions of people worldwide and created a global health concern with major complications like microcephaly and Guillain Barre’s syndrome. To date, there is not a single Zika-specific licensed drug present in the market. However, in recent months, several antiviral molecules have been screened against ZIKV. Among those, (−)-epigallocatechin-3-gallate (EGCG), a green tea polyphenol, has shown great virucidal potential against flaviviruses including ZIKV. The mechanistic understanding of EGCG-targeting viral proteins is not yet entirely deciphered except that little is known about its interaction with viral envelope protein and viral protease. We designed our current study to find inhibitory actions of EGCG against ZIKV NS3 helicase. NS3 helicase performs a significant role in viral replication by unwinding RNA after hydrolyzing NTP. We employed molecular docking and simulation approach and found significant interactions at the ATPase site and also at the RNA binding site. Further, the enzymatic assay has shown significant inhibition of NTPase activity with an IC50 value of 295.7 nM and Ki of 0.387 ± 0.034 μM. Our study suggests the possibility that EGCG could be considered as a prime backbone molecule for further broad-spectrum inhibitor development against ZIKV and other flaviviruses.

Effects of Epigallocatechin-3-Gallate (EGCG) on Cell Cycle Distribution and DNA Integrity of K562 Cells, A Human Chronic Myeloid Leukemia

Epigallocatechin-3-gallate (EGCG) is a naturally derived compound from green tea with high antioxidant activity and various anti-cancer properties. EGCG has been widely investigated worldwide. However, effects of EGCG on cell cycle of K562 have not been clearly stated elsewhere. This study was conducted with the aim to investigate the antiproliferative effect of EGCG on K562 human leukemic cells and its underlying mechanism of action on the cells. MTT assay was conducted to determine cytotoxicity effect of EGCG on the K562 cells. Meanwhile, cell cycle analysis and DNA damage on the cells were determined by Flow cytometry and Comet assay respectively. K562 cells were treated with EGCG at concentrations ranging from 0 to 100μg/ml for 48 hours. The results showed that EGCG effectively decreased the percentage of cell viability in a dose dependent manner. The IC10, IC25 and IC50 of EGCG on K562 cell lines were 5 ± 2.44 μg/mL, 10 ± 5.93 μg/mL and 50 ± 1.93 μg/mL, respectively. In cell cycle assay, EGCG has shown no significant effect (p>0.05) on the cell cycle of K562 cell line as compared to negative control, whereas Imatinib mesylate as the positive control showed cell cycle arrest at S phase in this cell line. Hence, EGCG can be verified as a non-cell cycle specific compound. In addition, EGCG was found to cause a significant increase (p<0.05) in tail moment value and percentage of DNA tail in K562 cell line, suggesting DNA damage as an early signal of EGCG induced cell cytotoxicity. In conclusion, by decreasing the cell viability and inducing DNA damage, EGCG showed promising potential as an alternative treatment for leukemia through non-cell cycle specific pathway and further investigation on other mechanisms of action of EGCG on the cells is recommended. DOI: http://dx.doi.org/10.17576/JSKM-2020-1801-08

EGCG exerts its protective effect by mitigating the release of lysosomal enzymes in aged rat liver on exposure to high cholesterol diet.

The aim is to test the hypothesis whether the cholesterol loaded lysosomes are capable of mediating lysosomal membrane permeabilization (LMP) during aging and to study the efficacy of epigallocatechin-3-gallate (EGCG) in preserving the lysosomal membrane stability. Aged rats were fed with high cholesterol diet (HCD) and treated with EGCG orally. Serum and tissue lipid status, cholesterol levels in lysosomal fraction, activities of lysosomal enzymes in lysosomal, and cytosolic fractions were measured. Transmission electron microscopic studies (TEM), oil red "O" (ORO) staining, and immunohistochemical analysis of oxidized low density lipoprotein (OxLDL) were carried out. Significant increase in serum, tissue lipid profile, and lysosomal cholesterol levels were observed in aged HCD-fed rats with a concomitant decrease in high density lipoprotein (HDL) levels. We also observed a significant increase in lipid accumulation in hepatocytes of aged HCD-fed rats by TEM, ORO, and immunohistochemical staining. Upon treatment with EGCG to aged HCD-fed animals, we found augmented levels of HDL with a concomitant decrease in lysosomal cholesterol levels and other lipoproteins. TEM studies and immunohistochemistry of OxLDL also showed a marked reduction in lipid deposition of hepatocytes. Thus, EGCG has preserved the lysosomal membrane stability in HCD stressed aged rats. SIGNIFICANCE OF THE STUDY: The research article is focused mainly on the effect of EGCG and its capability on mitigating the release of lysosomal enzymes in aged animals fed with HCD. The study signifies the cellular function of the organelle lysosome following administration of aged rats with HCD, which would make the readers to understand the action of EGCG and the interrelationship of both cholesterol and activity of lysosomes when cholesterol is loaded.

Characteristics, Stability and Activity of Epigallocatechin Gallate (EGCG)-Chitosan Microspheres: Effect of Polymer Concentration

Epigallocatechin gallate (EGCG) is a natural product compound which has known to have anticancer activity. However, its bioavailability was low of 0.1% limited by poor stability. This study was aimed to produce microspheres as drug delivery system to improve the stability of drug. EGCG-Chitosan microspheres were formed by ionotropic gelation-aerosolization technique and were produced from chitosan and sodium tripolyphosphate. This study evaluated effect of 1, 2 and 3% of chitosan concentration on physical characteristics, stability and activity of EGCG-Chitosan microspheres. Physical characteristics were evaluated in terms of particle size, morphology, moisture content, entrapment efficiency, drug loading, yield, swelling index, physical stability and activity. Stability was evaluated by measuring size, entrapment efficiency and drug loading at 25°C and 50°C temperature for storage period of 7, 14, 21 and 30 days. Activity test was evaluated with MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay using HeLa cells. Particle sizes of formula were 2.29, 2.68, and 3.11 µm respectively with entrapment efficiency of 33.94, 52.27, 62.14% and drug loading of 23.25, 29.36, and 32.24 % correspondingly. Morphology was spherical with smooth surface. Yields were 78.25, 79.36, and 79.77% respectively. No significant differences between all formulas indicated that microspheres were stable during storage. Activity results showed that formula with chitosan 3% was the most active as anti-cervical cancer showing by IC50 was 83.58 µg/mL. EGCG-chitosan microspheres demonstrated potential as drug delivery system and as anti-cervical cancer.

Induction of Endoplasmic Reticulum Stress Pathway by Green Tea Epigallocatechin-3-Gallate (EGCG) in Colorectal Cancer Cells: Activation of PERK/p-eIF2α/ATF4 and IRE1α.

Epigallocatechin-3-gallate (EGCG) is the most abundant bioactive polyphenolic compound among the green tea constituents and has been identified as a potential anticancer agent in colorectal cancer (CRC) studies. This study was aimed to determine the mechanism of actions of EGCG when targeting the endoplasmic reticulum (ER) stress pathway in CRC. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay was performed on HT-29 cell line and normal cell line (3T3) to determine the EGCG toxicity. Next, western blot was done to observe the expression of the related proteins for the ER stress pathway. The Caspase 3/7 assay was performed to determine the apoptosis induced by EGCG. The results demonstrated that EGCG treatment was toxic to the HT-29 cell line. EGCG induced ER stress in HT-29 by upregulating immunoglobulin-binding (BiP), PKR-like endoplasmic reticulum kinase (PERK), phosphorylation of eukaryotic initiation factor 2 alpha subunit (eIF2α), activating transcription 4 (ATF4), and inositol-requiring kinase 1 alpha (IRE1α). Apoptosis was induced in HT-29 cells after the EGCG treatment, as shown by the Caspase 3/7 activity. This study indicates that green tea EGCG has the potential to inhibit colorectal cancer cells through the induction of ER stress.

Protective Effect of Epigallocatechin Gallate in Ischemia-Reperfusion Injury of Rat Skeletal Muscle

BackgroundReactive oxygen species–induced cell injury has been considered to be one of the main etiologic factors in ischemia-reperfusion injury (IRI). As a potential antioxidant agent, epigallocatechin gallate (EGCG) was examined in skeletal muscle of the rats after IRI with or without treatment. Materials and methodsTourniquet application applied to the rats’ hind limbs was selected as the appropriate IRI method. Animals were randomly distributed to one of the following groups: (1) sham control + SF (saline) (10 mg/kg/i.p.) (SC-SF), (2) IRI (4 + 2 h) + SF (10 mg/kg/i.p.) (IRI-SF), (3) IRI and EGCG (25 mg/kg/i.p.) (IRI-EG25), and (4) IRI and EGCG (50 mg/kg/i.p) (IRI-EG50). In another set of experiments with identical groups, the only difference was that the reperfusion period was 24 h. A number of different parameters relating to the damage seen in the skeletal muscles, lungs, kidneys, and liver and particular cytokines were measured by proper analytical methods. ResultsIn comparison with the SC-SF group, IRI (4 + 2 h) induced an increase in the total oxidative status of skeletal muscle (10.17 ± 0.61 versus 15.74 ± 1.10) and blood creatine phosphokinase (CPK) (669.88 ± 50.23 versus 7202.38 ± 766.13) and lactate dehydrogenase levels (686.00 ± 67.48 versus 1343.00 ± 113.01). Although 25 mg/kg EGCG could not reverse these parameters to their normal levels, the higher dose of EGCG, that is, 50 mg/kg, was sufficient to prevent the increases seen in total oxidative status (8.55 ± 0.85) and CPK levels (4741.63 ± 339.40). In addition, reduced total antioxidant status of skeletal muscle in the IRI-SF group (0.50 ± 0.06) was elevated by the administration of EGCG (50 mg/kg) (0.85 ± 0.04). Regarding remote organ injury, only alanine transaminase (ALT) and aspartate transaminase (AST) levels were found to be increased, showing a slight damage in liver tissue. However, neither dose of EGCG was able to prevent this deleterious effect. As for cytokines (interleukin-1β, IL-6, IL-8, tumor necrosis factor-α, and monocyte chemotactic protein-1), there were no differences between the study groups. In regard to long-term IRI (i.e., 4 + 24 h), statistically significantly elevated parameters in the IRI-SF group were as follows: CPK, lactate dehydrogenase, creatinine (Cr), and blood urea nitrogen. On the other hand, none of them were influenced by either dose of EGCG. According to the results, EGCG demonstrates a considerable protective effect toward IRI (4 + 2 h) of skeletal muscle. ConclusionsAlthough oxidative stress seems to play a significant role both in the pathogenesis of IRI and in the mechanism of action of EGCG, there is no evidence that inflammatory cytokines are, at least in our model, crucial mediators regarding the former events.

Epigallocatechin-3-gallate suppresses neutrophil migration speed in a transgenic zebrafish model accompanied by reduced inflammatory mediators.

BackgroundPolyphenol catechins from green tea, particularly (−)-epigallocatechin-3-gallate (EGCG), exhibits numerous beneficial health effects, although the mechanisms remain unclear. MethodsIn this study, the mechanism of EGCG-mediated healing in an experimentally injured zebrafish model was examined at the cellular and molecular level using confocal microscopy and gene expression analysis. ResultsThe mechanisms of action of EGCG were shown to involve: (1) reducing neutrophil response (accumulation, travel speed, and distance) and (2) downregulating the expression of IL-1β, TNFα, and related signaling pathways. As determined by dynamic time-lapse tracking studies, the local accumulation of neutrophils with high migration speeds after wounding (n=33 cells, v=0.020 μm/s, d=37.8 μm), underwent significant reduction following treatment with EGCG doses of 300 μM (n=22 cells, v=0.013 μm/s, d=39.5 μm) and 600 μM (n=18 cells, v=0.008 μm/s, d=9.53 μm). Reverse transcription polymerase chain reaction studies revealed that several signature genes in the IL-1β, TNFα, and related signaling pathways were downregulated after EGCG treatment. ConclusionThe convenience, transparency, and simplicity of the zebrafish model facilitate tracking of fluorescent neutrophils in real time, in order to monitor inflammation, and assess the impact of therapeutic agents.

Encapsulation of epigallocatechin-3-gallate into albumin nanoparticles improves pharmacokinetic and bioavailability in rat model.

In the present study, we fabricated epigallocatechin-3-gallate (EGCG) loaded albumin nanoparticles (Alb-NP-EGCG) to enhance bioavailability and improve pharmacokinetic parameters of EGCG. The physicochemical properties of the Alb-NP-EGCG were studied using scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction and in vitro release studies. Characterization of Alb-NP-EGCG indicated the formation of spherical nanoparticles with no drug and excipient interaction. Alb-NP-EGCG showed a high drug loading capacity of 92%. Further, in vitro study showed a sustained release of EGCG from Alb-NP-EGCG over a period of 48h. Mathematical modeling and release kinetics indicated that the Alb-NP-EGCG followed zero order kinetic and EGCG was released via fickian diffusion method. In vivo bioavailability and distribution of Alb-NP-EGCG showed an enhanced plasma concentration of EGCG with 1.5 fold increase along with prolonged T 1/2 of 15.6h in the system when compared with the free EGCG. All this study demonstrated the fabrication of EGCG loaded albumin nanoparticles which favored the slow and sustained release of EGCG with improved pharmacokinetics and bioavailability thereby prolonging the action of EGCG. Additional acute and sub-acute toxicity test of the Alb-NP-EGCG demonstrated the safety of the Alb-NP-EGCG. Therefore, the Alb-NP-EGCG could be a promising drug delivery system for EGCG.

Epigallocatechin-3-gallate inhibits the growth and increases the apoptosis of human thyroid carcinoma cells through suppression of EGFR/RAS/RAF/MEK/ERK signaling pathway

BackgroundThyroid cancer is the most common type of endocrine malignancy and the incidence rate is rapidly increasing worldwide. Epigallocatechin-3-gallate (EGCG) could suppress cancer growth and induce apoptosis in many types of cancer cells. However, the mechanism of action of EGCG on the growth of human thyroid carcinoma cells has not been fully illuminated.MethodsCell proliferation and viability were detected by EdU and MTS assays. Cell cycle distribution was measured by flow cytometry. Migration and invasion were evaluated by scratch and transwell assays. Apoptotic levels were detected by TUNEL staining and western blotting. The protein levels of EGFR/RAS/RAF/MEK/ERK signaling pathway were detected by western blotting. The in vivo results were determined by tumor xenografts in nude mice. The in vivo proliferation, tumor microvessel density, and apoptosis were detected by immunohistochemistry.ResultsEGCG inhibited the proliferation, viability, and cell cycle progression in human thyroid carcinoma cells. EGCG decreased the migration and invasion, but increased the apoptosis of human thyroid carcinoma cells. EGCG reduced the protein levels of phospho (p)-epidermal growth factor receptor (EGFR), H-RAS, p-RAF, p-MEK1/2, and p-extracellular signal-regulated protein kinase 1/2 (ERK1/2) in human thyroid carcinoma cells. EGCG inhibited the growth of human thyroid carcinoma xenografts by inducing apoptosis and down-regulating angiogenesis.ConclusionsEGCG could reduce the growth and increase the apoptosis of human thyroid carcinoma cells through suppressing the EGFR/RAS/RAF/MEK/ERK signaling pathway. EGCG can be developed as an effective therapeutic agent for the treatment of thyroid cancer.

Molecular Targets of Epigallocatechin-Gallate (EGCG): A Special Focus on Signal Transduction and Cancer.

Green tea is a beverage that is widely consumed worldwide and is believed to exert effects on different diseases, including cancer. The major components of green tea are catechins, a family of polyphenols. Among them, epigallocatechin-gallate (EGCG) is the most abundant and biologically active. EGCG is widely studied for its anti-cancer properties. However, the cellular and molecular mechanisms explaining its action have not been completely understood, yet. EGCG is effective in vivo at micromolar concentrations, suggesting that its action is mediated by interaction with specific targets that are involved in the regulation of crucial steps of cell proliferation, survival, and metastatic spread. Recently, several proteins have been identified as EGCG direct interactors. Among them, the trans-membrane receptor 67LR has been identified as a high affinity EGCG receptor. 67LR is a master regulator of many pathways affecting cell proliferation or apoptosis, also regulating cancer stem cells (CSCs) activity. EGCG was also found to be interacting directly with Pin1, TGFR-II, and metalloproteinases (MMPs) (mainly MMP2 and MMP9), which respectively regulate EGCG-dependent inhibition of NF-kB, epithelial-mesenchimal transaction (EMT) and cellular invasion. EGCG interacts with DNA methyltransferases (DNMTs) and histone deacetylases (HDACs), which modulates epigenetic changes. The bulk of this novel knowledge provides information about the mechanisms of action of EGCG and may explain its onco-suppressive function. The identification of crucial signalling pathways that are related to cancer onset and progression whose master regulators interacts with EGCG may disclose intriguing pharmacological targets, and eventually lead to novel combined treatments in which EGCG acts synergistically with known drugs.

Epigallocatechin-3 Gallate Inhibits STAT-1/JAK2/IRF-1/HLA-DR/HLA-B and Reduces CD8 MKG2D Lymphocytes of Alopecia Areata Patients.

Background: Alopecia areata (AA) is associated with Interferon- γ (IFN-γ) mediated T-lymphocyte dysfunction and increased circulating Interleukine-17 (IL-17) levels. Epigallocatechin-3-gallate (EGCG) specifically inhibits IFN-γ pathways and unlike Janus Kinase 1 and 2 (JAK1/JAK2) inhibitors (tofacitinib, ruxolitinib), EGCG is safer, more cost-effective, and is a topically active agent. Our objective is to test the mode of action of EGCG in vitro and ex vivo using HaCat, Jurkat cell lines, and peripheral blood mononuclear cells (PBMCs) of AA patients and healthy controls (HCs), respectively. Methods: distribution of T helper cells (Th1, Th17), and cytotoxic cells (CD8) in PBMCs isolated from 30 AA patients and 30 HCs was investigated by flowcytomterty. In vitro treatment of HaCat and Jurkat cells with 40 μm EGCG for 48 h was performed to measure the level of phosphorylation of signal transducer and activator of transcription protein STAT1, and replicated in ex vivo model using PBMCs of AA patients. Results: Interestingly, 40 μm EGCG is capable of completely inhibiting phosphorylation of STAT1 after 48 h in HaCat and Jurkat cells and ex vivo in PBMCs of AA patients. Based on QPCR data, the action of EGCG on p-STAT1 seems to be mediated via downregulation of the expression of JAK2 but not JAK1 leading to the inhibition of human leukocyte antigens (HLA-DR and HLA-B) expression probably via IRF-1. On the other hand, AA patients have significantly increased levels of Th1, Th17, and CD8 cells and the production of IFN-γ and IL-17 by PBMCs in AA patients was significantly higher compared to HC; p = 0.008 and p = 0.006, respectively. Total numbers of CD8+ cells were not significantly different between treated and untreated samples. However, CD8+ cells with positive Natural killer group 2 member D (NKG2D) transmembrane receptor (CD8+ NKG2D+ subset) was significantly reduced when PBMCs were treated with 20 μm EGCG for 48 h. Conclusion: These results suggest that EGCG has a synergistic action that inhibits expression of HLA-DR and HLA-B molecules via the IFN-γ pathway to maintain immune privilege in HF; also it reduces CD8+ NKG2D+ subset.

Molecular Defects in Cardiac Myofilament Ca2+-Regulation Due to Cardiomyopathy-Linked Mutations Can Be Reversed by Small Molecules Binding to Troponin.

The inherited cardiomyopathies, hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are relatively common, potentially life-threatening and currently untreatable. Mutations are often in the contractile proteins of cardiac muscle and cause abnormal Ca2+ regulation via troponin. HCM is usually linked to higher myofilament Ca2+-sensitivity whilst in both HCM and DCM mutant tissue there is often an uncoupling of the relationship between troponin I (TnI) phosphorylation by PKA and modulation of myofilament Ca2+-sensitivity, essential for normal responses to adrenaline. The adrenergic response is blunted, and this may predispose the heart to failure under stress. At present there are no compounds or interventions that can prevent or treat sarcomere cardiomyopathies. There is a need for novel therapies that act at a more fundamental level to affect the disease process. We demonstrated that epigallocatechin-3 gallate (EGCG) was found to be capable of restoring the coupled relationship between Ca2+-sensitivity and TnI phosphorylation in mutant thin filaments to normal in vitro, independent of the mutation (15 mutations tested). We have labeled this property “re-coupling.” The action of EGCG in vitro to reverse the abnormality caused by myopathic mutations would appear to be an ideal pharmaceutical profile for treatment of inherited HCM and DCM but EGCG is known to be promiscuous in vivo and is thus unsuitable as a therapeutic drug. We therefore investigated whether other structurally related compounds can re-couple myofilaments without these off-target effects. We used the quantitative in vitro motility assay to screen 40 compounds, related to C-terminal Hsp90 inhibitors, and found 23 that can re-couple mutant myofilaments. There is no correlation between re-couplers and Hsp90 inhibitors. The Ca2+-sensitivity shift due to TnI phosphorylation was restored to 2.2 ± 0.01-fold (n = 19) compared to 2.0 ± 0.24-fold (n = 7) in wild-type thin filaments. Many of these compounds were either pure re-couplers or pure desensitizers, indicating these properties are independent; moreover, re-coupling ability could be lost with small changes of compound structure, indicating the possibility of specificity. Small molecules that can re-couple may have therapeutic potential.HIGHLIGHTS - Inherited cardiomyopathies are common diseases that are currently untreatable at a fundamental level and therefore finding a small molecule treatment is highly desirable.- We have identified a molecular level dysfunction common to nearly all mutations: uncoupling of the relationship between troponin I phosphorylation and modulation of myofilament Ca2+-sensitivity, essential for normal responses to adrenaline.- We have identified a new class of drugs that are capable of both reducing Ca2+-sensitivity and/or recouping the relationship between troponin I phosphorylation and Ca2+-sensitivity.- The re-coupling phenomenon can be explained on the basis of a single mechanism that is testable.- Measurements with a wide range of small molecules of varying structures can indicate the critical molecular features required for recoupling and allows the prediction of other potential re-couplers.

Green Tea Polyphenol EGCG Alleviates Metabolic Abnormality and Fatty Liver by Decreasing Bile Acid and Lipid Absorption in Mice.

The tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) has been shown to ameliorate metabolic abnormalities and fatty liver. The present study investigates the mechanisms of actions of EGCG on bile acid homeostasis and lipid metabolism. Male C57BL/6J mice are fed a low-fat diet, a high-fat western-style diet, or a high-fat western-style diet containing 0.32% EGCG. The effects of the treatments on biochemical parameters, gene expression, and lipidomics are analyzed. EGCG treatment significantly reduces body weight gain, mesenteric fat mass, fasting blood glucose, insulin resistance, serum cholesterol, and severity of fatty liver after treatment for 17 weeks, but most of these effects were less apparent at week 33. At week 17, EGCG treatment significantly elevates the mRNA levels of cholesterol 7α-hydroxylase, HMG-CoA reductase, low-density lipoprotein receptor, and scavenger receptor B1, and partially normalizes the high-fat diet induced lipidomic profile. The intestinal bile acid content is significantly decreased by EGCG, while fecal excretion of bile acids, cholesterol, and total lipids are increased. EGCG decreases bile acid reabsorption, results in lower intestinal bile acid levels, which further decreases the absorption of lipids. These actions contribute to the alleviation of metabolic abnormalities and fatty liver disease caused by the high-fat diet.

Epigallocatechin-3-Gallate Regulates Anti-Inflammatory Action Through 67-kDa Laminin Receptor-Mediated Tollip Signaling Induction in Lipopolysaccharide-Stimulated Human Intestinal Epithelial Cells

Background/Aims: Inflammatory bowel disease (IBD) is a condition that involves chronic inflammation in all or part of the digestive tract. Often painful and debilitating, IBD can lead to life-threatening complications and increase the risk for colon cancer. In this study, we investigated the epigallocatechin-3-gallate (EGCG) mediated anti-inflammation response in lipopolysaccharide (LPS)-stimulated human colorectal cells through the negative regulator of Toll-like receptor (TLR) signaling. Methods: human intestinal epithelial cells (HT-29) were used in all experiments. Cell cytotoxicity and nitric oxide (NO) were evaluated by WST-1 and the Griess reagent. Western blot analysis and ELISA were used to determine inflammatory mediators and 67-kDa laminin receptor (67LR)-mediated Tollip signaling pathways. Results: Treatment of EGCG and LPS did not affect the cytotoxicity in HT-29 cells. LPS treatment dose-dependently increased the pro-inflammatory cytokine, such as interleukin (IL)-8, whereas EGCG significantly reduced the LPS-stimulated IL-8 production. Additionally, EGCG treatment markedly increased the Toll-interacting protein (Tollip) expression, which negatively regulates the TLR signaling in a dose and time-dependent manner. In particular, in the result from an RNA interference-mediated assay, our finding showed that silencing of Tollip resulted in abrogation of the inhibitory action of EGCG on LPS-induced production of pro-inflammatory mediators (inducible nitric oxide synthase-mediated NO/COX2, and IL-8) and activation of MAPKs and NF-κB signaling pathways. Interestingly, we also found that Tollip expression induced by EGCG could be modulated through 67LR expressed on the surface of HT-29 cells. Conclusions: Our novel finding indicates that 67LR and Tollip signaling activated by EGCG treatment is essential for inhibition of inflammation in human intestinal epithelial cells.