Inhibitory Effect Of Epigallocatechin-3-gallate Research Articles

Effect of EGCG Extracted from Green Tea against Largemouth Bass Virus Infection.

(1) Background: Largemouth bass virus (LMBV) is a major viral pathogen in largemouth bass (Micropterus salmoides) aquaculture that often causes high mortality and heavy economic losses, thus developing treatments to combat this pathogen is of great commercial importance. Green tea is a well-known medicinal plant that contains active ingredients with antiviral, antibacterial, and other biological activities. The goals of this study were to explore the effect and mechanism of green tea source compounds on LMBV and provide data to serve as the basis for the screening of targeted drugs in the future. In this study, we evaluated the effects of the main component of green tea, epigallocatechin-3-gallate (EGCG), against LMBV infection. (2) Methods: The safe working concentration of EGCG was identified by cell viability detection and light microscopy. The antiviral activity and mechanism of action of EGCG against LMBV infection were evaluated with light microscopy, an aptamer 6-carboxy-fluorescein-based fluorescent molecular probe, and reverse transcription quantitative PCR. (3) Results: The safe working concentration of EGCG was ≤10 μg/mL. EGCG showed significant anti-LMBV infection activity in a concentration-dependent manner, and it also destroyed the structure of virus particles. EGCG impacted the binding of virus particles to cell receptors and virus invasion into the host cells. Inhibitory effects of EGCG on LMBV particles, LMBV binding to the host-cell membrane, and LMBV invasion were 84.89%, 98.99%, and 95.23%, respectively. Meanwhile, the effects of EGCG subsequently were verified in vivo. The fatality rate of the LMBV + EGCG group was significantly lower than that of the LMBV group. (4) Conclusions: Our results suggest that EGCG has effective antiviral properties against LMBV and may be a candidate for the effective treatment and control of LMBV infections in largemouth bass aquaculture.

Epigallocatechin Gallate and Isoquercetin Synergize With Remdesivir to Reduce SARS-CoV-2 Replication In Vitro

The ongoing pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) urgently needs effective antivirals. After over 2 years since the beginning of the pandemic, only a few FDA approved therapeutic options are available to treat the population. Combination therapies have become a standard for the treatment of other infectious diseases such as HIV and hepatitis C due to their improved efficacy compared to monotherapy, reduced toxicity, the ability to prevent the development of resistant viral strains and their potential to treat co-infection. The interest in identifying molecules displaying bioactivity against SARS-CoV-2 has led to extensive search for promising molecules from the natural pharmacopoeia and polyphenols have been shown to display antiviral activity against a number of viruses including SARS-CoV-2. Here we evaluated the in vitro efficacy of two polyphenols, Epigallocatechin gallate (EGCG) and Isoquercetin, in combination with Remdesivir, the first-approved drug for the treatment of severe COVID-19. We confirmed the inhibitory effects of EGCG and isoquercetin against SARS-CoV-2 and demonstrated their strong antiviral synergistic effects with Remdesivir in vitro. These combinational therapies represent an interesting avenue for the treatment of COVID-19 and grant further studies.

Epigallocatechin Gallate Relieved PM2.5-Induced Lung Fibrosis by Inhibiting Oxidative Damage and Epithelial-Mesenchymal Transition through AKT/mTOR Pathway.

Oxidative damage and epithelial-mesenchymal transition (EMT) are main pathological processes leading to the development of PM2.5-induced lung fibrosis. Epigallocatechin gallate (EG), a natural polyphenol extracted from green tea, possesses the ability to combat oxidative stress and inflammation. However, the potential roles of EG in PM2.5-induced lung fibrosis have not been reported yet. In the present study, we investigated whether EG could relieve PM2.5-induced lung injury and fibrosis in vivo and in vitro. To mimic PM2.5-induced lung fibrosis, C57/BL6 mice were intranasally instilled with PM2.5 suspension, and MLE-12 lung epithelial cells were stimulated with PM2.5 (100 μg/mL) in vitro. The results showed that intragastric administration of EG (20 mg/kg/d or 80 mg/kg/d for 8 weeks) significantly prevented lung injury, inflammation, and oxidative stress in PM2.5-induced mice, apart from inhibiting collagen deposition. Additionally, EG treatment also suppressed the activation of AKT/mTOR signaling pathway in lung tissues challenged with PM2.5. In vitro experiments further demonstrated that EG treatment could enhance cell viability in a concentration-dependent manner in PM2.5-treated MLE-12 lung epithelial cells. Also, the overexpression of constitutively active AKT could offset the inhibitory effects of EG on EMT and oxidative stress in PM2.5-treated MLE-12 lung epithelial cells. Finally, AKT overexpression also blocked the inhibitory effect of EG on the phosphorylation of mTOR in PM2.5-treated MLE-12 lung epithelial cells. In conclusion, EG could improve PM2.5-induced lung fibrosis by decreasing oxidative damage and EMT through AKT/mTOR pathway, which might be a potential candidate for the treatment of PM2.5-induced lung fibrosis.

EGCG Inhibits Tumor Growth in Melanoma by Targeting JAK-STAT Signaling and Its Downstream PD-L1/PD-L2-PD1 Axis in Tumors and Enhancing Cytotoxic T-Cell Responses.

Over the last decade, therapies targeting immune checkpoints, such as programmed death-1 (PD-1), have revolutionized the field of cancer immunotherapy. However, low response rates and immune-related adverse events remain a major concern. Here, we report that epigallocatechin gallate (EGCG), the most abundant catechin in green tea, inhibits melanoma growth by modulating an immune response against tumors. In vitro experiments revealed that EGCG treatment inhibited interferon-gamma (IFN-γ)-induced PD-L1 and PD-L2 expression and JAK-STAT signaling. We confirmed that this effect was driven by inhibiting STAT1 gene expression and STAT1 phosphorylation, thereby downregulating the PD-L1/PD-L2 transcriptional regulator IRF1 in both human and mouse melanoma cells. Animal studies revealed that the in vivo tumor-inhibitory effect of EGCG was through CD8+ T cells and that the inhibitory effect of EGCG was comparable to anti-PD-1 therapy. However, their mechanisms of action were different. Dissimilar to anti-PD-1 treatment that blocks PD-1/PD-L1 interaction, EGCG inhibited JAK/STAT signaling and PD-L1 expression in tumor cells, leading to the re-activation of T cells. In summary, we demonstrate that EGCG enhances anti-tumor immune responses by inhibiting JAK-STAT signaling in melanoma. EGCG could be used as an alternative treatment strategy to target the PD-L1/PD-L2-PD-1 axis in cancers.

Food phytochemicals, epigallocatechin gallate and myricetin, covalently bind to the active site of the coronavirus main protease in vitro

SARS-CoV-2 main protease is a possible target for protection against viral infection. This study examined the inhibitory effect of food phytochemicals on the main protease of SARS-CoV-2 by determining a cleaved product after chromatographic separation. First, 37 phytochemicals, including glycosides and metabolites, were screened at 20 µM; epigallocatechin gallate, myricetin, theaflavin, herbacetin, piceatannol, myricitrin, and isothiocyanates inhibited the enzyme in varying degrees. The IC50 values were estimated from 0.4 to 33.3 µM against the 0.5-µM enzyme. The dose-dependent adduction of epigallocatechin gallate and myricetin was confirmed by quinone staining of protein blotted onto a membrane. The enzyme activity was decreased by increasing the concentration of the two phytochemicals, accompanied by increasing the respective adducted molecule estimated by intact mass spectrometry. Reduced glutathione canceled the formation of conjugate and the inhibitory effect of epigallocatechin gallate or myricetin on the enzyme, suggesting that the formation of the quinone moiety in the phytochemicals is critical for the inhibition. The covalent binding of epigallocatechin gallate or myricetin to the cysteine residue at the active site was confirmed by analyzing peptides from the chymotrypsin-digested main protease.

Dual effect of epigallocatechine gallate on the pathology of Alzheimer s: Cholinesterases and amyloidogenesis

Aim: To evaluate the dual inhibitory effect of epigallocatechin gallate on Alzheimer’s pathogenesis. Methods: Cholinesterase inhibition studies were performed by kinetic Ellman methods and also the inhibitory effect of molecule on amyloid fibrillation is determined by dye binding thioflavin T method. Results: Epigallocatechin gallate inhibited both types of cholinesterases and amyloid fibrillation. The inhibition of acetylcholinesterase indicated an uncompetitive inhibition whereas butyrylcholinesterase inhibition had an unique pattern. Compound inhibited butyrylcholinesterase with two types of inhibition in a dose related manner. Fibrillation destabilization is also observed by the compound. Conclusion: Our results indicated that epigallocatechin gallate may be accepted as a candidate molecule as the dual effective drugs for neurodegenerative diseases.

Liver extracellular matrix hydrogel-based three-dimensional culture system of HepG2 cells to enhance cancer stem cell properties

Both extracellular matrix (ECM) components and three-dimensional (3D) structure play important roles in the expression and maintenance of cancer stem cell (CSC) properties. Considering the excellent biophysical and biochemical properties of hydrogels, the objective of this study was to develop a 3D cell culture system based on liver ECM hydrogel (LEMH) to enhance CSC properties. Results showed that LEMH was devoid of cellular materials but contained the main components of the liver ECM. HepG2 hepatocellular carcinoma cells cultured in LEMH displayed cluster growth and formed multilayer 3D cell structures with increased expression of hepatocyte-specific genes compared to two-dimensional (2D) cells. In addition, enhanced CSC characteristics, including migration, self-renewal and drug-resistance, were observed in 3D cells. More importantly, inhibitory effects of epigallocatechin gallate on CSC self-renewal and metastatic characteristics were observed, confirming the applicability of the LEMH-based 3D model for the research and development of CSC-specific drugs. These findings suggest that LEMH-based 3D culture offers a simple and efficient platform to enhance CSC properties in vitro, thereby providing a novel approach for exploring CSC-specific agents and chemotherapeutic drugs.

Inhibitory effects of epigallocatechin gallate (EGCG) combined with zinc sulfate and silver nanoparticles on avian influenza A virus subtype H5N1.

Even though antiviral drugs against H5N1 flu infection are accessible, they are still limited by antiviral drug resistance and unfavorable side effects. Thus, this work tested the action of epigallocatechin gallate (EGCG) co-administered with both zinc (II) ions and silver nanoparticles (AgNPs). EGCG was used with both zinc sulfate (zinc II) and silver nanoparticles to test their antiviral activities against avian flu subtype H5N1 in embryonated SPF eggs. The MTS test was used to determine the cytotoxicity. Zinc sulfate (1.5 mg/mL) and silver nanoparticles showed comparable potentiated antiviral action with EGCG (50 μM) against the H5N1 avian flu virus. They decreased the log titer infection by up to 5.7 and 5.6 fold separately with critical antiviral activity (p<0.01). In most cases, an illustrative relationship was seen when H5N1 was tested with EGCG and various concentrations of zinc sulfate. The EGCG-AgNPs with zinc sulfate were observed to have very strong antiviral activity (p<0.001) against the H5N1 avian influenza virus with a reduction in the log titer of the virus by up to 7.6 times. No cytotoxicity was recognized. The potentiated antiviral activity of EGCG by co-administering it with zinc II and AgNPs indicates potential as a multi-activity novel topical therapeutic agent against H5N1 flue. This mix makes the adaptation of the virus difficult, which helps to reduce infection resistance.

Investigation on the influence of galloyl moiety to the peptidyl prolyl cis/trans isomerase Pin1: A spectral and computational analysis

In this research, we carried out spectral and computational methods to investigate the influence of galloyl moiety on Pin1. The fluorescence emission spectra revealed that the fluorescence quenching of Pin1 by epigallocatechin-3-gallate (EGCG) was a simultaneous dynamic and static quenching process, whereas the fluorescence quenching of Pin1 by epigallocatechin (EGC) was only a static quenching. In addition, the studies also indicated that the binding sites of EGCG and EGC to Pin1 were 2 and 1, respectively. Thermodynamic parameters, binding models, computational simulations and predicted binding free energy implied that hydrogen bonds, van der Waals and hydrophobic interactions were main binding forces in the Pin1-EGCG and Pin1-EGC systems. The synchronous and three-dimensional fluorescence, circular dichroism and Fourier transform infrared spectra illustrated that both EGCG and EGC could influence the conformation of Pin1. The fluorescence studies suggested that EGCG were bound to both the PPIase and WW domain, while EGC only was bound to the PPIase domain. The phenomena were further described using molecular docking and molecular dynamic simulations. Taken together, this research revealed that the inhibitory effect of EGCG on Pin1 was stronger than that of EGC, which was mainly due to the galloyl moiety.

Involvement of MicroRNA-296 in the Inhibitory Effect of Epigallocatechin Gallate against the Migratory Properties of Anoikis-Resistant Nasopharyngeal Carcinoma Cells.

Short noncoding endogenous RNAs, including microRNAs (miRNAs), are associated with the development and metastasis of multiple cancers. Epigallocatechin gallate (EGCG), the most active and abundant polyphenol in green tea, plays a crucial role in the modulation of miRNA expression, which is related to changes in cancer progression. In the present study, we explore whether EGCG exerts its suppressive effects on nasopharyngeal carcinoma (NPC) cells through miRNA regulation. The anoikis-resistant sphere-forming NPC cells grown under anchorage-independent conditions exhibit enhanced migratory properties, which were inhibited by EGCG treatment. The miR-296 level was lower in the anoikis-resistant cells than in the monolayer parental cells; however, miR-296 was significantly upregulated after EGCG treatment. We demonstrate that miR-296 is involved in the inhibitory effects of EGCG on the anoikis-resistant NPC cells through the downregulation of signal transducer and activator of transcription 3 (STAT3) activation. Our study is the first to demonstrate that EGCG inhibited the migratory properties of anoikis-resistant cells by modulating the expression of miRNA in NPC cells. Our results indicate the novel effects of EGCG on miRNA regulation to inhibit an invasive phenotype of NPC as well as the regulatory role of miR-296.

The Inhibitory Effect of (-)-Epigallocatechin-3-Gallate on Breast Cancer Progression via Reducing SCUBE2 Methylation and DNMT Activity.

Epigenetic modifications are important mechanisms responsible for cancer progression. Accumulating data suggest that (−)-epigallocatechin-3-gallate (EGCG), the most abundant catechin of green tea, may hamper carcinogenesis by targeting epigenetic alterations. We found that signal peptide-CUB (complement protein C1r/C1s, Uegf, and Bmp1)-EGF (epidermal growth factor) domain-containing protein 2 (SCUBE2), a tumor suppressor gene, was hypermethylated in breast tumors. However, it is unknown whether EGCG regulates SCUBE2 methylation, and the mechanisms remain undefined. This study was designed to investigate the effect of EGCG on SCUBE2 methylation in breast cancer cells. We reveal that EGCG possesses a significantly inhibitory effect on cell viability in a dose- and time-dependent manner and presents more effects than other catechins. EGCG treatment resulted in enhancement of the SCUBE2 gene, along with elevated E-cadherin and decreased vimentin expression, leading to significant suppression of cell migration and invasion. The inhibitory effect of EGCG on SCUBE2 knock-down cells was remarkably alleviated. Further study demonstrated that EGCG significantly decreased the SCUBE2 methylation status by reducing DNA methyltransferase (DNMT) expression and activity. In summary, this study reported for the first time that SCUBE2 methylation can be reversed by EGCG treatment, finally resulting in the inhibition of breast cancer progression. These results suggest the epigenetic role of EGCG and its potential implication in breast cancer therapy.

Inhibitory Effect of Epigallocatechin Gallate, Epigallocatechin, and Gallic Acid on the Formation of N-Nitrosodiethylamine In Vitro.

This study investigated the inhibitory effect of epigallocatechin gallate (EGCG), epigallocatechin (EGC), and gallic acid (GA) on the formation of N-nitrosodiethylamine (NDEA) in vitro. Results show that the three polyphenols are capable to block NDEA formation when the molar ratio of phenols to nitrite is higher than 0.8, and a more acidic environment is prone to promote the inhibitory potential of phenols. It is also found that the inhibitory effect tends to decrease in the order: EGCG, EGC, GA, which is in accordance with the order of their DPPH scavenging activity, suggesting that the inhibitory effect of polyphenols on NDEA formation may work through a free radical way. Kinetic study further revealed the three polyphenols react with nitrite at a much faster rate than diethylamine does (P < 0.05). By scavenging nitrite at a faster rate than the nitrosation of diethylamine, polyphenols at high concentration can significantly block NDEA formation. These observations may promote a possible application of polyphenol compounds to inhibit the formation of nitrosamines in food processing. PRACTICAL APPLICATION: The presence of N-nitrosamines in human diet should be an etiological risk factor for human cancers. This work may provide a useful guideline for phenolic compounds to inhibit the formation of nitrosamines in food processing, such as in the process of curing meats. Polyphenols have been proved to block NDEA formation under normal gastric juice condition, suggesting the intake of polyphenols is a potential way to prevent diseases caused by nitrite.

Epigallocatechin-3-Gallate Prevents Acute Gout by Suppressing NLRP3 Inflammasome Activation and Mitochondrial DNA Synthesis.

Gout is a chronic inflammatory disease evoked by the deposition of monosodium urate (MSU) crystals in joint tissues. The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome is responsible for the gout inflammatory symptoms induced by MSU crystals. We investigated whether epigallocatechin-3-gallate (EGCG) suppresses the activation of the NLRP3 inflammasome, thereby effectively preventing gouty inflammation. EGCG blocked MSU crystal-induced production of caspase-1(p10) and interleukin-1β in primary mouse macrophages, indicating its suppressive effect on the NLRP3 inflammasome. In an acute gout mouse model, oral administration of EGCG to mice effectively alleviated gout inflammatory symptoms in mouse foot tissue injected with MSU crystals. The in vivo suppressive effects of EGCG correlated well with the suppression of the NLRP3 inflammasome in mouse foot tissue. EGCG inhibited the de novo synthesis of mitochondrial DNA as well as the production of reactive oxygen species in primary mouse macrophages, contributing to the suppression of the NLRP3 inflammasome. These results show that EGCG suppresses the activation of the NLRP3 inflammasome in macrophages via the blockade of mitochondrial DNA synthesis, contributing to the prevention of gouty inflammation. The inhibitory effects of EGCG on the NLRP3 inflammasome make EGCG a promising therapeutic option for NLRP3-dependent diseases such as gout.

Diet supplemented with phytochemical epigallocatechin gallate and probiotic Lactobacillus fermentum confers second generation synbiotic effects by modulating cellular immune responses and antioxidant capacity in aging mice.

In the present study, we systematically identified and evaluated a synbiotic combination of phytochemical epigallocatechin gallate (EGCG) and probiotic bacteria in amelioration of immunosenescence and oxidative stress in aged mice. Inhibitory effects of EGCG against different bacterial species were evaluated in vitro, followed by analysis to identify potential combination of EGCG and probiotic bacteria against alleviation of oxidative and inflammatory stress ex vivo. The best synbiotic combination, vis-à-vis prebiotic and probiotic supplementation alone, was then evaluated in aged Swiss albino mice for modulation of various immunological and antioxidative parameters. EGCG strongly inhibited the growth of pathogenic microbes as compared to probiotic bacteria. A combination of EGCG with probiotic Lactobacillus fermentum (LF) provided evidence of additive effects in the amelioration of oxidative and inflammatory stress-induced cell death. In vivo study revealed that combined supplementation of LF and EGCG significantly enhanced neutrophil oxidative index, CD3+ cell numbers and activation status, Th1/Th2 cytokines in splenic supernatants as well as liver Nrf-2 expression in comparison with treatments with LF or EGCG alone. The combined application of EGCG and LF did not simply result in additive or synergistic effects in relation with individual treatments. These observations suggest that EGCG could be considered as a potential prebiotic that can offer second generation synbiotic health beneficial effects for the alleviation of some of the deleterious aspects of immunosenescence and aging.

GW29-e0508 EGCG inhibits Angiotensin II-induced cardiac hypertrophy in H9C2 via activate HIPPO signaling pathway

Angiotensin II (AngII) acts primarily on the central nervous system to increase the production of vasopressin,and also acts on veins and arterial smooth muscle to cause vasoconstriction.The purpose of this study was to investigate the potential inhibitory effects of epigallocatechin gallate (EGCG)

Epigallocatechin gallate inhibits hepatitis B virus infection in human liver chimeric mice

BackgroundPersistent hepatitis B virus (HBV) infection causes liver cirrhosis and hepatocellular carcinoma and constitutes a major worldwide health problem. Currently, anti-HBV drugs are limited to peginterferon and nucleos(t)ide analogs, which are costly and have considerable side effects; the development of novel, effective anti-HBV agents is crucial.MethodsCatechins are a major group of compounds found in green tea extract and epigallocatechin gallate (EGCG) has been shown to have antiviral properties, including inhibition of cellular entry by HBV. FRG (Fah−/−/ Rag2−/−/ IL-2Rγ/−) mice were used in this study to generate chimeras carrying human primary hepatocytes, to facilitate investigation of the inhibitory effect of EGCG on HBV infection.ResultsHere, we show the inhibitory effect of EGCG on HBV infection and replication in HuS-E/2 cells. The inhibitory effect of EGCG on HBV infection in vivo was confirmed by monitoring HBV DNA and HBsAg in serum and immunostaining the liver tissues of the human liver chimeric mice.ConclusionsThe effects of EGCG suggest a robust strategy for the treatment of HBV infection and EGCG may have therapeutic potential for the treatment of HBV-associated liver diseases.

Effects of epigallocatechin-3-gallate (EGCG) on skin greasiness and related gene expression in ‘Jonagold’ apple fruit during ambient storage

Some apple (Malus × domestica) cultivars can become greasy during ripening due to changes in their surface wax composition. Epicuticular waxes are derived by the de novo synthesis of fatty acids, catalyzed by fatty acid synthase (FAS). Epigallocatechin-3-gallate (EGCG) has previously been shown to be an inhibitor of FAS in both animals and bacteria. Therefore, we hypothesize it may also affect the development of postharvest skin greasiness in apples. In this study, ‘Jonagold’ apples were treated with EGCG and then stored at 20 °C. The composition of the surface waxes was analyzed and the expressions of genes related to wax synthesis were recorded. The results show that at these postharvest storage temperatures, the level of skin greasiness rises rapidly. This is consistent with measured increases in the content of the main fluid waxes - linoleate and oleate esters. Compared with the controls, the accumulation of fluid waxes was suppressed by EGCG at most stages during ambient storage. A number of genes related to fluid wax biosynthesis, including MdKASIII, MdKAR, MdFAD2 and MdWSD11, showed significant increases in expression during the development of skin greasiness. Meanwhile, the expressions of MdKASII and MdENR, the transport gene MdLTPG1 and the regulation gene MdSHN3 declined during storage. The expressions of all these genes were down-regulated by EGCG, while the fruit respiration and firmness were similar between the EGCG-treated and control fruit throughout the storage period. We suppose that the inhibitory effects of EGCG are to down-regulate expression levels of genes involved in wax biosynthesis. This results in reduced accumulation of the fluid wax components and delays and lowers the development of skin greasiness. Our results also indicate that MdFAD2 and MdWSD11 may be critical for formation of greasy esters in apple skins. This work is the first evaluation of the effects of EGCG on apple skin greasiness. The results supply useful information elucidating the mechanisms through which apple fruit skins can become greasy during postharvest storage.

Epigallocatechin-3-gallate suppresses differentiation of adipocytes via regulating the phosphorylation of FOXO1 mediated by PI3K-AKT signaling in 3T3-L1 cells

Epigallocatechin-3-gallate (EGCG) is a pivotal effective component of green tea. It is known that EGCG has antioxidant activity, anti-angiogenesis, anti-tumor, cardiovascular protection and blood lipid regulation functions. Forkhead box-O1 (FOXO1) is one of the downstream signals of protein kinase B (AKT) and takes part in adipogenesis. The purpose of this study is to investigate the effects of EGCG on adipose differentiation and the likely mechanisms. 3T3-L1 cells were induced by DMI for 2, 4, 6 and 8 days, respectively. During induction, the cells were treated with EGCG (5 μM, 10 μM, 50 μM and 100 μM) or DMSO for the first 2 days. In addition, another batch of 3T3-L1cells were treated with SC-3036 (PI3K activator, 10 µM), or LY294002 (PI3K inhibitor, 10 µM) alone or combined with EGCG (100 μM) for the indicated times. Medium glucose concentration, lipid accumulation, the levels of TNF-α, resistin, adiponectin and leptin and the expression of FOXO1, phosphorylated-FOXO1 (P-FOXO1), PPARγ, fatty acid synthase (FAS) were detected, respectively. The present study demonstrated that EGCG inhibited glucose uptake, lipid accumulation and adipokine secretion in a concentration-dependent manner during adipogenesis, which suggests that EGCG inhibits adipocyte’s differentiation, maturation and functions. Moreover, EGCG also down-regulated the expression levels of PPARγ and P-FOXO1. Conversely, the PI3K activator reversed these changes caused by EGCG, suggesting that the inhibitory effects of EGCG may be mediated by PI3K-AKT-FOXO1 pathway to negatively regulate the expression of PPARγ. The findings will provide a solid foundation for EGCG to prevent and cure the obesity-associated diseases.

Epigallocatechin-3-gallate inhibits inflammation and epithelial‑mesenchymal transition through the PI3K/AKT pathway via upregulation of PTEN in asthma.

Asthma is a chronic disease associated with hyper-responsiveness, obstruction and remodeling of the airways. Epithelial-mesenchymal transition (EMT) has an important role in these alterations and may account for the accumulation of subepithelial mesenchymal cells, thus contributing to airway hyperresponsiveness and remodeling. Epigallo-catechin-3-gallate (EGCG), which is a type of polyphenol, is the most potent ingredient in green tea, and exhibits antibacterial, antiviral, antioxidative, anticancer and chemopreventive activities. Recently, numerous studies have investigated the protective effects of EGCG against asthma and other lung diseases. In the present study, the role of EGCG in ovalbumin (OVA)-challenged asthmatic mice was determined. In addition, the inhibitory effects of EGCG against transforming growth factor (TGF)-β1-induced EMT and migration of 16HBE cells, and the underlying mechanisms of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway, were investigated by immunofluorescence, Transwell, wound healing assay and western blot analysis, respectively. The results indicated that EGCG may suppress inflammation and inflammatory cell infiltration into the lungs of OVA-challenged asthmatic mice, and may also inhibit EMT via the PI3K/AKT signaling pathway through upregulating the expression of phosphatase and tensin homolog (PTEN) in vivo and in vitro. The present study also revealed the anti-migratory effects of EGCG in TGF-β1-induced 16HBE cells, thus suggesting it may reduce airway remodeling. The present study provides a novel insight into understanding the protective effects of EGCG on airway remodeling in asthma, and indicates that EGCG may be useful as an adjuvant therapy for bronchial asthma.

(-)-Epigallocatechin-3-gallate Down-regulates Doxorubicin-induced Overexpression of P-glycoprotein Through the Coordinate Inhibition of PI3K/Akt and MEK/ERK Signaling Pathways.

(-)-Epigallocatechin-3-gallate (EGCG) has been indicated to regulate the function of P-glycoprotein (P-gp), which is a drug transporter encoded by the MDR1 (ABCB1) gene. P-gp expression is induced by doxorubicin (DOX). We aimed to clarify the mechanisms and inhibitory effects of EGCG on DOX-induced P-gp expression in HepG2 cells. Rhodamine 123 (Rho123) was used for P-gp substrate. Western blotting and polymerase chain reactions (PCRs) were conducted using specific antibodies and primer sets. The DOX-pretreated cells accumulated a significantly decreased amount of Rho123), than control cells; however, the cells pretreated with EGCG and DOX, in combination, accumulated Rho123 more than DOX-pretreated cells. DOX induced the overexpression of MDR1 mRNA and increased the phosphorylation of Akt, ERK1/2, p38 MAPK and JNK. EGCG significantly inhibited the phosphorylation of Akt and ERK. The DOX-induced P-gp overexpression was partially suppressed by an inhibitor of MEK1/2 (U0126), but not by a PI3K inhibitor (LY294002). Interestingly, the expression of P-gp was synergistically inhibited by combined treatment of U0126 with LY294002 and also inhibited by an mTORC1 inhibitor, rapamycin. EGCG inhibited DOX-induced overexpression of P-gp through the coordinate inhibitory action on MEK/ERK and PI3K/Akt signaling pathways.