High-pressure microfluidization enhanced the stability of sodium caseinate-EGCG complex-stabilized fish oil emulsion

Improving the emulsion-stabilizing effect of protein by chemical or physical modification has been paid much attention recently. Here, sodium caseinate (CS) was treated by high-pressure-microfluidization (HPM) under 0-100 MPa, and was further complexed with (-)-epigallocatechin-3-gallate (EGCG) to form an excellent emulsifier that stabilized fish oil emulsions. Results showed that HPM treatment (especially 80 MPa) significantly changed the secondary structure of CS, and 80 MPa-PCS-EGCG had the best emulsifying and antioxidant activities. In addition, after HPM treatment and EGCG bonding, CS formed a thicker interface layer on the surface of oil droplets, which could better protect the fish oil from the influence by oxygen, temperature and ion concentration. Moreover, the fish oil emulsion stabilized by PCS-EGCG complex significantly delayed the release of free fatty acids subjected to in vitro digestion. Conclusively, HPM-treated CS-EGCG complex could be a potential emulsifier to improve the stability of fish oil emulsions.

Fabrication and characterization of oleogels stabilized by metal-phenolic network coatings-decorated zein nanoparticles

Self-assembly coatings are used to functionalize the surface structures of protein. Herein, emulsion-templated approach was adopted to obtain oleogels using metal-phenolic network coatings-decorated zein nanoparticles. Two self-assembly strategies were used to decorate zein nanoparticles: 1) adding (-)-epigallocatechin-3-gallate (EGCG) first and then calcium ions (Ca2+) (zein/EGCG/Ca2+ nanoparticles). 2) adding Ca2+ first and then EGCG (zein/Ca2+/EGCG nanoparticles). The formation of nanoparticles, the stability of emulsions and the rheological behaviors of oleogels were modulated by using different adding sequences of EGCG and Ca2+. Nanoparticles prepared by two self-assembly strategies exhibited increasing diameter (340-360 nm). More Ca2+ participated in the formation of zein/EGCG/Ca2+ nanoparticles, as described by X-ray photoelectron spectroscopy analysis. Metal-phenolic network coatings facilitated the formation of well-structured emulsions and oleogels, which were candidates for fat substitutes and stable carriers. Findings confirmed metal-phenolic network coatings-decorated zein nanoparticles were effective stabilizers for emulsions and oleogels, further expanding the selectivity of oleogelators.

(-)-Epigallocatechin-3-Gallate Attenuates the Adverse Reactions Triggered by Selenium Nanoparticles without Compromising Their Suppressing Effect on Peritoneal Carcinomatosis in Mice Bearing Hepatocarcinoma 22 Cells

Increasing evidence shows that selenium and polyphenols are two types of the most reported compounds in tumor chemoprevention due to their remarkable antitumor activity and high safety profile. The cross-talk between polyphenols and selenium is a hot research topic, and the combination of polyphenols and selenium is a valuable strategy for fighting cancer. The current work investigated the combination anti-peritoneal carcinomatosis (PC) effect of selenium nanoparticles (SeNPs) and green tea (Camellia sinensis) polyphenol (-)-epigallocatechin-3-gallate (EGCG) in mice bearing murine hepatocarcinoma 22 (H22) cells. Results showed that SeNPs alone significantly inhibited cancer cell proliferation and extended the survival time of mice bearing H22 cells. Still, the potential therapeutic efficacy is accompanied by an approximately eighty percent diarrhea rate. When EGCG was combined with SeNPs, EGCG did not affect the tumor proliferation inhibition effect but eliminated diarrhea triggered by SeNPs. In addition, both the intracellular selectively accumulated EGCG without killing effect on cancer cells and the enhanced antioxidant enzyme levels in ascites after EGCG was delivered alone by intraperitoneal injection indicated that H22 cells were insensitive to EGCG. Moreover, EGCG could prevent SeNP-caused systemic oxidative damage by enhancing serum superoxide dismutase, glutathione, and glutathione peroxidase levels in healthy mice. Overall, we found that H22 cells are insensitive to EGCG, but combining EGCG with SeNPs could protect against SeNP-triggered diarrhea without compromising the suppressing efficacy of SeNPs on PC in mice bearing H22 cells and attenuate SeNP-caused systemic toxicity in healthy mice. These results suggest that EGCG could be employed as a promising candidate for preventing the adverse reactions of chemotherapy including chemotherapy-induced diarrhea and systemic toxicity in cancer individuals.

Antimicrobial synergistic effects of apigenin, (-)-epigallocatechin-3-gallate, myricetin and luteolin in combination with some antibiotics

INTRODUCTION AND OBJECTIVE

Antimicrobial resistance, which is considered one of the most important problems of the 21 st century, brings many problems with it, such as increasing mortality rates and treatment costs. Difficulties in the treatment of infections caused by resistant microorganisms have led to the search and need for new antimicrobials or new molecules that interact synergistically with antimicrobials. The aim of this study is to investigate whether various flavonoids have synergistic effects with some antibiotics.

MATERIAL AND METHODS

During this study, standard bacterial strains Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603, Pseudomonas aeruginosa ATCC 9027, Staphylococcus aureus ATCC 29213 and Staphylococcus aureus ATCC 43300 were used. Minimal inhibitory concentrations of all antibiotics and flavonoids were found by the broth microdilution method. Interactions between antibiotics and flavonoids were then determined by using the checkerboard method. Interactions between antibiotics and flavonoids were evaluated according to the FIC index (ΣFIC) results.

RESULTS

According to the results of the microdilution test, the bacterial strains used in this study (except for MRSA) were generally sensitive to antibiotics. Interaction study results showed promising results regarding the synergistic interactions of antibiotics with flavonoids. Epigallocatechin gallate and luteolin especially showed synergistic interaction with antibiotics in many microorganisms. It was found that myricetin showed synergistic interaction only with levofloxacin. Likewise, it was detected that apigenin had limited synergistic interaction with antibiotics.

CONCLUSIONS

The obtained results highlight that flavonoids may be a useful tool in overcoming antibiotic resistance.

Comparing the Effects of Encapsulated and Non-Encapsulated Propolis Extracts on Model Lipid Membranes and Lactic Bacteria, with Emphasis on the Synergistic Effects of Its Various Compounds

Propolis is a resinous compound made by bees with well-known biological activity. However, comparisons between encapsulated and non-encapsulated propolis are lacking. Therefore, the antibacterial activity, effect on the phase transition of lipids, and inhibition of UV-induced lipid oxidation of the two forms of propolis were compared. The results showed that non-encapsulated propolis produces quicker effects, thus being better suited when more immediate effects are required (e.g., antibacterial activity). In order to gain an in-depth introspective on these effects, we further studied the synergistic effect of propolis compounds on the integrity of lipid membranes. The knowledge of component synergism is important for the understanding of effective propolis pathways and for the perspective of modes of action of synergism between different polyphenols in various extracts. Thus, five representative molecules, all previously isolated from propolis (chrysin, quercetin, trans-ferulic acid, caffeic acid, (-)-epigallocatechin-3-gallate) were mixed, and their synergistic effects on lipid bilayers were investigated, mainly using DSC. The results showed that some compounds (quercetin, chrysin) exhibit synergism, whereas others (caffeic acid, t-ferulic acid) do not show any such effects. The results also showed that the synergistic effects of mixtures composed from several different compounds are extremely complex to study, and that their prediction requires further modeling approaches.

Physicochemical Properties and Oxidative Stability of an Emulsion Prepared from (-)-Epigallocatechin-3-Gallate Modified Chicken Wooden Breast Myofibrillar Protein

The deterioration of wooden breast myofibrillar protein (WBMP) causes a decline in its processing performance, and the protein becomes easier to oxidize. Previous studies have revealed that the use of (-)-epigallocatechin-3-gallate (EGCG) may improve the physicochemical properties and oxidative stability of proteins in aqueous solutions. The effects of varying concentrations (0.01%, 0.02%, 0.03%, and 0.04% w/v) of EGCG on the physicochemical properties of a WBMP emulsion (1.2% WBMP/10% oil) and the inhibition of lipid and protein oxidation were studied. The results revealed that a moderate dose of EGCG (0.03%) could significantly (p < 0.05) improve the emulsion activity index (4.66 ± 0.41 m2/g) and emulsion stability index (91.95 ± 4.23%), as well as reduce the particle size of the WBMP emulsion. According to the micrographs and cream index, 0.03% EGCG retarded the phase separation by stopping the aggregation of droplets and proteins, thus significantly improving the stability of WBMP emulsions. During storage at 50 °C for 96 h, 0.03% EGCG inhibited lipid oxidation (lipid hydroperoxide and 2-thiobarbituric acid-reactive substance formation) and protein oxidation (carbonyl formation and sulfhydryl loss). In contrast, lower and higher EGCG concentrations (0.01%, 0.02%, and 0.04%) demonstrated shortcomings (such as weak antioxidant capacity or protein over-aggregation) in improving the quality and oxidation stability of the emulsion. In conclusion, a moderate dose of EGCG (0.03%) can be used to improve the quality and shelf life of WBMP emulsions.

Conjugation of (-)-epigallocatechin-3-gallate and protein isolate from large yellow croaker (Pseudosciaena crocea) roe: improvement of antioxidant activity and structural characteristics

BACKGROUND

Large yellow croaker (Pseudosciaena crocea) roe is the main by-product in the processing of large yellow croaker. Previous studies have found that its protein isolates are composed of vitellogenin, as well as vitellogenin B and C, having good functional properties. (-)-Epigallocatechin-3-gallate (EGCG) is a natural antioxidant component that can be combined with protein to improve antioxidant activity and structural characteristics of protein.

RESULTS

EGCG was bound with the P. crocea roe protein isolate (pcRPI) by the free radical method to prepare the conjugate. The formation of pcRPI-EGCG conjugates was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel permeation chromatography, which showed that the calculated weight-average molar masses of native-pcRPI and pcRPI-EGCG conjugates were 86.9 and 215.3 kDa, respectively. The results of fluorescence, ultraviolet, circular and infrared spectra indicated that the conjugation of EGCG with native-pcRPI changed the secondary and tertiary structure of native-pcRPI. The pcRPI-EGCG conjugates exhibited higher thermal stability than native-pcRPI. The radical scavenging and reducing power of native-pcRPI were increased by 2.0-2.5- and 1.4-fold, respectively, after the EGCG-grafting reaction.

CONCLUSION

These results indicate that the binding of pcRPI and EGCG effectively improved the antioxidant properties and structural characteristics of the pcRPI. © 2021 Society of Chemical Industry.

Antigenotoxic effects of (-)-epigallocatechin-3-gallate (EGCG) and its relationship with the endogenous antioxidant system, 8-hydroxydeoxyguanosine adduct repair (8-OHdG), and apoptosis in mice exposed to chromium(VI)

This study aimed to investigate the relationship between endogenous antioxidant system, 8-hydroxydeoxyguanosine adduct (8-OHdG) repair, and apoptosis in mice treated with chromium(VI) alone and in the presence of the antigenotoxic compound (-)-epigallocatechin-3-gallate (EGCG). Groups of 5 Hsd:ICR male mice were divided and treated as follows: (1) control, vehicle only; (2) EGCG, 8.5 mg/kg by gavage alone; (3) CrO₃, 20 mg/kg intraperitoneally alone; and (4) EGCG combined with CrO₃, EGCG was administered 4 hr prior to CrO₃. Peripheral blood parameters were analyzed before treatment administration (time 0), and 48 hr after exposure. The administration of EGCG increased 8-OHdG levels and superoxide dismutase (SOD) activity. Treatment with CrO₃ increased number of micronucleus (MN) presence, elevated apoptotic/necrotic cells frequencies, decreased 8-OHdG levels, diminished total antioxidant capacity (TAC), increased glutathione (GSH) total levels, and lowered SOD activity. Administration of EGCG prior to treatment with CrO₃ resulted in lower concentrations of MN, reduced apoptotic and necrotic cell number, and restored TAC and SOD activity to control levels. It is conceivable that the dose of EGCG plays an important role in the genotoxic damage protection pathways. Thus, this study confirms the action of EGCG as an antigenotoxic agent against chromium(VI)-induced oxidative insults and demonstrates potential protective pathways for EGCG actions to counteract genotoxic damage induced by this metal.

Epigallocatechin-3-gallate exhibits antiviral effects against the duck Tembusu virus via blocking virus entry and upregulating type I interferons

The duck Tembusu virus (DTMUV) is a novel mosquito-borne Flavivirus which caused huge economic losses for poultry industries in Southeast Asia and China. Currently, no effective antiviral drugs against this virus have been reported. (-)-Epigallocatechin-3-gallate (EGCG), a polyphenol present in abundance in green tea, has recently been demonstrated to have an antiviral activity for many viruses; however, whether EGCG can inhibit DTMUV infection remains unknown. Here, we tried to explore the anti-DTMUV effects and mechanisms of EGCG both in vitro and in vivo. Several EGCG treatment regimens were used to study the comprehensive antiviral activity of EGCG in DTMUV-infected baby hamster kidney cell line (BHK-21). The DTMUV titers of mock- and EGCG-treated infected cell cultures were determined using the tissue culture infective dose assay and the DTMUV mRNA copy number as determined using quantitative Real Time PCR. Moreover, the therapeutic efficacy of EGCG against DTMUV was assessed in DTMUV-infected ducklings. Our results suggested that EGCG significantly reduced the viral infection in BHK-21 cells in a dose-dependent manner, as reflected by the reduction of virus titers, virus copy number, and the expressions of viral E protein. We also observed that EGCG exhibited direct virucidal abilities against DTMUV. Notably, a significant reduction in virus binding ability was also observed, indicating that EGCG possesses excellent inhibitory effects on the viral adsorption step. In addition, DTMUV replication was also suppressed in BHK-21 cells treated with EGCG after viral entry, likely because of upregulation of the levels of interferon alfa and interferon beta. Finally, we also proved that EGCG exhibited anti-DTMUV efficacy in a duckling infection model because the survival rate was significantly improved. This is the first study to demonstrate the protective effect of EGCG against DTMUV, suggesting its potential use as an antiviral drug for DTMUV infection.

(-)-Epigallocatechin-3-Gallate Inhibits eNOS Uncoupling and Alleviates High Glucose-Induced Dysfunction and Apoptosis of Human Umbilical Vein Endothelial Cells by PI3K/AKT/eNOS Pathway

INTRODUCTION

Diabetes can increase the risk of cardiovascular disease. This study aimed to explore the effect of (-)-epigallocatechin-3-gallate (EGCG) on high glucose (HG)-induced dysfunction and apoptosis of vascular endothelial cells.

MATERIALS AND METHODS

The viability of human umbilical vein endothelial cells (HUVECs) treated with different concentrations and times of EGCG was detected by CCK-8 assay. The expression levels of ROS, NO and BH4 in HUVECs after treatment were detected by respective ELISA kits. The expression of p-eNOS, eNOS, NOX4, bcl2, bax, cleaved-caspase3, caspase3, p-PI3K, p-AKT, PI3K and AKT in HUVECs was detected by Western blot analysis. The apoptosis of HUVECs after treatment was analyzed by TUNEL assay.

RESULTS

The viability of HUVECs was not obviously changed when treated with different concentrations and times of EGCG. The expression of ROS, NOX4 and eNOS (monomer) was increased, while the expression of NO, p-eNOS, eNOS, BH4 and eNOS (dimer) was decreased in HUVECs of HG group. EGCG could gradually reverse the effect of high glucose on HG-treated HUVECs from 10 μM to 50 μM. The apoptosis of HUVECs was also increased in HG group and EGCG decreased the apoptosis of HUVECs. PI3K/AKT signaling pathway was suppressed in HG-treated HUVECs while activated by EGCG treatment. When the PI3K/AKT signaling pathway was inhibited by LY294002 (AKT inhibitor), the protective effect of EGCG on HG-treated HUVECs was weakened.

CONCLUSION

EGCG could inhibit eNOS uncoupling and alleviate endothelial dysfunction and apoptosis of HG-treated HUVECs by activating the PI3K/AKT/eNOS pathway.

(-)-Epigallocatechin-3-gallate suppresses cigarette smoke-induced inflammation in human cardiomyocytes via ROS-mediated MAPK and NF-κB pathways

BACKGROUND

Cigarette smoking is the leading cause for the initiation and development of cardiovascular disease (CVD). Oxidative stress and inflammatory responses play important roles in the pathophysiological processes of smoking-induced cardiac injury. (-)-epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea, which is made from Camellia sinensis leaves, has been reported to possess potent anti-oxidant property.

PURPOSE

This study aims to investigate whether the antioxidant EGCG could alleviate cigarette smoke medium (CSM)-induced inflammation in human AC16 cardiomyocytes in vitro.

METHODS

Human AC16 cardiomyocytes were pre-treated with EGCG, N-acetyl-L-cysteine (NAC), or specific inhibitors for 30 min before 4% CSM was added. Supernatant was collected for determination of interleukin (IL)-8 by ELISA and cells were collected for flow cytometry, biochemical assays and Western blot analysis.

RESULTS

EGCG treatment significantly attenuated CSM-induced oxidative stress as evidenced by reducing intracellular and mitochondrial reactive oxygen species (ROS) generations and preventing antioxidant depletion. EGCG treatment reduced CSM-induced inflammatory chemokine interleukin (IL)-8 productions in the supernatant via the inhibition of ERK1/2, p38 MAPK and NF-κB pathways. EGCG treatment further inhibited CSM-induced cell apoptosis.

CONCLUSION

Taken together, EGCG protected against CSM-induced inflammation and cell apoptosis by attenuating oxidative stress via inhibiting ERK1/2, p38 MAPK, and NF-κB activation in AC16 cardiomyocytes. These findings suggest that EGCG with its antioxidant, anti-inflammatory and anti-apoptotic properties may act as a promising cardioprotective agent against ROS-mediated cardiac injury.

(-)-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.

Potential Biological Effects of (-)-Epigallocatechin-3-gallate on the Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a major health issue throughout the world. However, no validated treatments for NAFLD are currently available. In-depth studies have demonstrated the efficacy of (-)-epigallocatechin-3-gallate (EGCG), a main bioactive chemical extracted from green tea, in treating NAFLD. EGCG exhibits multi-pronged preventive and therapeutic activities, including promoting lipid and glucose metabolism, anti-lipid peroxidation and anti-inflammation activities, anti-fibrosis, and anti-NAFLD related tumor, thus contributing to the mitigation of NAFLD occurrence and progression. The objectives of this paper are to review and discuss the currently known targets, signaling pathways and roles of EGCG that interfere with NAFLD pathogenesis, then providing additional experimental evidence and the foundation for the further studies and clinical applications of EGCG in the prevention and treatment of NAFLD.

(-)-Epigallocatechin-3-gallate Ameliorates Insulin Resistance and Mitochondrial Dysfunction in HepG2 Cells: Involvement of Bmal1

SCOPE

Normal physiological processes require a robust biological timer called the circadian clock. Dysregulation of circadian rhythms contributes to a variety of metabolic syndrome, including obesity and insulin resistance. (-)-Epigallocatechin-3-gallate (EGCG) has been demonstrated to possess antioxidant, anti-inflammatory, and cardioprotective bioactivities. The objective of this study was to explore whether the circadian clock is involved in the protective effect of EGCG against insulin resistance.

METHODS AND RESULTS

The results demonstrated that EGCG reverses the relatively shallow daily oscillations of circadian clock genes transcription and protein expression induced by glucosamine in HepG2 cells. EGCG also alleviates insulin resistance by enhancing tyrosine phosphorylated levels of IRS-1, stimulating the translocation of GLUT2, and activating PI3K/AKT as well as AMPK signaling pathways in a Bmal1-dependent manner both in HepG2 cells and primary hepatocytes. Glucosamine-stimulated excessive secretions of ROS and depletions of mitochondrial membrane potential were notably attenuated in EGCG co-treated HepG2 cells, which consistent with the recovery in expression of mitochondrial respiration complexes.

CONCLUSION

The results demonstrated that EGCG possesses a Bmal1-dependent efficacy against insulin resistance conditions by strengthening the insulin signaling and eliminating oxidative stress, suggesting that EGCG may serve as a promising natural nutraceutical for the regulation of metabolic disorders relevant to circadian clocks.

Potential Biological Effects of (-)-Epigallocatechin-3-gallate on the Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a major health issue throughout the world. However, no validated treatments for NAFLD are currently available. In‐depth studies have demonstrated the efficacy of (‐)‐epigallocatechin‐3‐gallate (EGCG), a main bioactive chemical extracted from green tea, in treating NAFLD. EGCG exhibits multi‐pronged preventive and therapeutic activities, including promoting lipid and glucose metabolism, anti‐lipid peroxidation and anti‐inflammation activities, anti‐fibrosis, and anti‐NAFLD related tumor, thus contributing to the mitigation of NAFLD occurrence and progression. The objectives of this paper are to review and discuss the currently known targets, signaling pathways and roles of EGCG that interfere with NAFLD pathogenesis, then providing additional experimental evidence and the foundation for the further studies and clinical applications of EGCG in the prevention and treatment of NAFLD.

(-)-Epigallocatechin-3-gallate and atorvastatin treatment down-regulates liver fibrosis-related genes in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) and associated advanced liver diseases have become prevalent conditions in many countries and are associated with increased mortality. Gene expression profiles in NAFLD have been examined recently but changes in expression elicited by chemical compound treatments have not been investigated. Since (-)-Epigallocatechin-3-gallate (EGCG) and atorvastatin (ATST) exhibit similar efficacy in NAFLD models, we reasoned that some common key genes might alter after treatment of EGCG and ATST. Accordingly, we applied integrated bioinformatics analyses of RNA microarray data from EGCG and ATST treatment groups compared to controls in a NAFLD phenotypic mouse model. Using differential expression (DE) analysis, Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis, Gene Set Enrichment Analysis (GSEA) and ClueGO enrichment, shared EGCG and ATST down-regulated pathways were identified which included extracellular matrix (ECM)-receptor interaction and protein processing in endoplasmic reticulum (ER). To refine key genes associated with liver fibrosis, a human NAFLD signature derived from patients of different fibrosis stages was analyzed. The results showed that fibrosis-related genes Col1a1, Col1a2, Col3a1 and Col6a3 were significantly down-regulated. These four genes were further validated as down-regulated in an independent mouse NAFLD dataset. We conclude that EGCG and ATST treatment results in the significant down-regulation of genes related to liver fibrosis.

Potential Role of (-)-Epigallocatechin-3-Gallate (EGCG) in the Secondary Prevention of Alzheimer Disease

Medical advances in the last decades have increased the average life expectancy, but also the incidence and prevalence of age-associated neurodegenerative diseases. Alzheimer's disease (AD) is one of the most common neurodegenerative diseases and the most prevalent type of dementia. A plethora of different mechanisms contribute to AD, among which oxidative stress plays a key role in its development and progression. So far, there are no pharmacological treatments available and the current medications are mainly symptomatic. In the last years, dietary polyphenols have gained research attention due to their interesting biological activities, and more specifically their antioxidant properties. (-)- Epigallocatechin-3-gallate (EGCG) is a natural flavanol that has been extensively studied regarding its potential effects in AD. In this review we present the current in vitro and in vivo experimentation regarding the use of EGCG in AD. We also review the complex mechanisms of action of EGCG, not only limited to its antioxidant activity, which may explain its beneficial health effects.

(-)-Epigallocatechin-3-gallate Reduces Cigarette Smoke-Induced Airway Neutrophilic Inflammation and Mucin Hypersecretion in Rats

Background: Cigarette smoking is the leading cause of chronic obstructive pulmonary disease. (-)-Epigallocatechin-3-gallate (EGCG), the major catechins in Chinese green tea, has been studied for its anti-oxidative and anti-inflammatory properties in cell and animal models. In this study, we aimed to analyze the effects of EGCG on cigarette smoke (CS)-induced airway inflammation and mucus secretion in the CS-exposed rat model. Methods: Male Sprague-Dawley rats were randomly divided into either sham air (SA) or CS exposure. EGCG (50 mg/kg b.wt.) was given by oral gavage every other day in both SA and CS-exposed animals. Oxidative stress and inflammatory markers were determined in serum and/or bronchoalveolar lavage fluid by biochemical assays or ELISA. Lung morphological changes were examined by Periodic Acid-Schiff, Masson's Trichrome staining and immunohistochemical analysis. Western blot analysis was performed to explore the effects of EGCG on epidermal growth factor receptor (EGFR)-mediated signaling pathway. Results: (-)-Epigallocatechin-3-gallate treatment attenuated CS-induced oxidative stress, lung cytokine-induced neutrophil chemoattractant-1 release and neutrophil recruitment. CS exposure caused an increase in the number of goblet cells in line with MUC5AC upregulation, and increased lung collagen deposition, which were alleviated in the presence of EGCG. In addition, CS-induced phosphorylation of EGFR in rat lung was abrogated by EGCG treatment. Conclusion: (-)-Epigallocatechin-3-gallate treatment ameliorated CS-induced oxidative stress and neutrophilic inflammation, as well as airway mucus production and collagen deposition in rats. The present findings suggest that EGCG has a therapeutic effect on chronic airway inflammation and abnormal airway mucus production probably via inhibition of EGFR signaling pathway.

Recent Advances in Anticancer Activities and Drug Delivery Systems of Tannins

Tannins, polyphenols in medicinal plants, have been divided into two groups of hydrolysable and condensed tannins, including gallotannins, ellagitannins, and (-)-epigallocatechin-3-gallate (EGCG). Potent anticancer activities have been observed in tannins (especially EGCG) with multiple mechanisms, such as apoptosis, cell cycle arrest, and inhibition of invasion and metastases. Furthermore, the combinational effects of tannins and anticancer drugs have been demonstrated in this review, including chemoprotective, chemosensitive, and antagonizing effects accompanying with anticancer effect. However, the applications of tannins have been hindered due to their poor liposolubility, low bioavailability, off-taste, and shorter half-life time in human body, such as EGCG, gallic acid, and ellagic acid. To tackle these obstacles, novel drug delivery systems have been employed to deliver tannins with the aim of improving their applications, such as gelatin nanoparticles, micelles, nanogold, liposomes, and so on. In this review, the chemical characteristics, anticancer properties, and drug delivery systems of tannins were discussed with an attempt to provide a systemic reference to promote the development of tannins as anticancer agents.

Combined Treatment With Environmental Enrichment and (-)-Epigallocatechin-3-Gallate Ameliorates Learning Deficits and Hippocampal Alterations in a Mouse Model of Down Syndrome

Intellectual disability in Down syndrome (DS) is accompanied by altered neuro-architecture, deficient synaptic plasticity, and excitation-inhibition imbalance in critical brain regions for learning and memory. Recently, we have demonstrated beneficial effects of a combined treatment with green tea extract containing (-)-epigallocatechin-3-gallate (EGCG) and cognitive stimulation in young adult DS individuals. Although we could reproduce the cognitive-enhancing effects in mouse models, the underlying mechanisms of these beneficial effects are unknown. Here, we explored the effects of a combined therapy with environmental enrichment (EE) and EGCG in the Ts65Dn mouse model of DS at young age. Our results show that combined EE-EGCG treatment improved corticohippocampal-dependent learning and memory. Cognitive improvements were accompanied by a rescue of cornu ammonis 1 (CA1) dendritic spine density and a normalization of the proportion of excitatory and inhibitory synaptic markers in CA1 and dentate gyrus.

Principal Component Analysis of the Effects of Environmental Enrichment and (-)-epigallocatechin-3-gallate on Age-Associated Learning Deficits in a Mouse Model of Down Syndrome

Down syndrome (DS) individuals present increased risk for Alzheimer's disease (AD) neuropathology and AD-type dementia. Here, we investigated the use of green tea extracts containing (-)-epigallocatechin-3-gallate (EGCG), as co-adjuvant to enhance the effects of environmental enrichment (EE) in Ts65Dn mice, a segmental trisomy model of DS that partially mimics DS/AD pathology, at the age of initiation of cognitive decline. Classical repeated measures ANOVA showed that combined EE-EGCG treatment was more efficient than EE or EGCG alone to improve specific spatial learning related variables. Using principal component analysis (PCA) we found that several spatial learning parameters contributed similarly to a first PC and explained a large proportion of the variance among groups, thus representing a composite learning measure. This PC1 revealed that EGCG or EE alone had no significant effect. However, combined EE-EGCG significantly ameliorated learning alterations of middle age Ts65Dn mice. Interestingly, PCA revealed an increased variability along learning sessions with good and poor learners in Ts65Dn, and this stratification did not disappear upon treatments. Our results suggest that combining EE and EGCG represents a viable therapeutic approach for amelioration of age-related cognitive decline in DS, although its efficacy may vary across individuals.

The effects of N-acetylcysteine and epigallocatechin-3-gallate on liver tissue protein oxidation and antioxidant enzyme levels after the exposure to radiofrequency radiation

PURPOSE

The widespread and sustained use of mobile and cordless phones causes unprecedented increase of radiofrequency radiation (RFR). The aim of this experimental study was to investigate the effect of 900 MHz Global System for Mobile Communications (GSM)-modulated RFR (average whole body Specific Absorption Rate (SAR) of 0.4 W/kg, 10 or 20 min daily for consecutive 7 days) to the liver tissue of guinea pigs and the protective effects of antioxidant treatments.

MATERIALS AND METHODS

Adult male guinea pigs were randomly divided into nine groups as: Group I (sham/saline), Group II (sham/EGCG), Group III (sham/NAC), Group IV (10-min RF-exposure/saline), Group V (20-min RF-exposure/saline), Group VI (10-min RF-exposure/EGCG), Group VII (20-min RF-exposure/EGCG), Group VIII (10-min RF-exposure/NAC), and Group IX (20-min RF-exposure/NAC). Protein oxidation (PCO), advanced oxidation protein products (AOPP) and antioxidant enzyme activities of superoxide dismutase (SOD) were evaluated after the exposure and the treatments with N-acetylcysteine (NAC) and (-)-epigallocatechin-3-gallate (EGCG).

RESULTS AND CONCLUSIONS

Significant decreases in the activities of SOD were observed in the liver of guinea pigs after RFR exposure. Protein damage did not change due to RFR exposure. On the other hand, only NAC treatment induced increased PCO levels, whereas EGCG treatment alone elevated the level of AOPP. Due to antioxidants having pro-oxidant behavior, the well decided doses and treatment timetables of NAC and ECGC are needed.

Inhibition of microsomal cortisol production by (-)-epigallocatechin-3-gallate through a redox shift in the endoplasmic reticulum--a potential new target for treating obesity-related diseases

Conversion of cortisone to cortisol by 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) in the endoplasmic reticulum (ER) of the target cells is a major determinant of glucocorticoid action, and plays an important role in the development of obesity-related diseases. Inhibition of 11βHSD1 activity is, therefore, considered as a promising novel strategy for the treatment of metabolic syndrome and diabetes. Tea flavanols and their major representative, epigallocatechin gallate are known as antiobesity and antidiabetic agents. Their impacts on blood glucose level, hepatic glucose production, and insulin responsiveness resemble those observed on inhibition or depletion of 11βHSD1. We aimed to study the effect of epigallocatechin gallate on 11βHSD1 activity in ER-derived rat liver microsomes by measuring cortisone and cortisol with HPLC. Cortisol production was efficiently suppressed in a concentration dependent manner in intact microsomal vesicles. However, this effect was abolished by membrane permeabilization; and the three proteins involved in the overall process (11βHSD1, hexose 6-phosphate dehydrogenase, and glucose 6-phosphate transporter) were not or only mildly affected. Further investigation revealed the oxidation of luminal NADPH to NADP⁺, which attenuates cortisone reduction and favors cortisol oxidation in this compartment. Such a redox shift in the ER lumen might contribute to the beneficial health effects of tea flavanols and should be regarded as a promising strategy for the development of novel selective 11βHSD1 inhibitors to treat obesity-related diseases.

Suppression of esophageal cancer cell growth using curcumin, (-)-epigallocatechin-3-gallate and lovastatin

AIM: To determine the effects of curcumin, (-)-epigallocatechin-3-gallate (EGCG), lovastatin, and their combinations on inhibition of esophageal cancer.

METHODS: Esophageal cancer TE-8 and SKGT-4 cell lines were subjected to cell viability methyl thiazolyl tetrazolium and tumor cell invasion assays in vitro and tumor formation and growth in nude mouse xenografts with or without curcumin, EGCG and lovastatin treatment. Gene expression was detected using immunohistochemistry and Western blotting in tumor cell lines, tumor xenografts and human esophageal cancer tissues, respectively.

RESULTS: These drugs individually or in combinations significantly reduced the viability and invasion capacity of esophageal cancer cells in vitro. Molecularly, these three agents reduced the expression of phosphorylated extracellular-signal-regulated kinases (Erk1/2), c-Jun and cyclooxygenase-2 (COX-2), but activated caspase 3 in esophageal cancer cells. The nude mouse xenograft assay showed that EGCG and the combinations of curcumin, EGCG and lovastatin suppressed esophageal cancer cell growth and reduced the expression of Ki67, phosphorylated Erk1/2 and COX-2. The expression of phosphorylated Erk1/2 and COX-2 in esophageal cancer tissue specimens was also analyzed using immunohistochemistry. The data demonstrated that 77 of 156 (49.4%) tumors expressed phosphorylated Erk1/2 and that 121 of 156 (77.6%) esophageal cancers expressed COX-2 protein. In particular, phosphorylated Erk1/2 was expressed in 23 of 50 (46%) cases of esophageal squamous cell carcinoma (SCC) and in 54 of 106 (50.9%) cases of adenocarcinoma, while COX-2 was expressed in 39 of 50 (78%) esophageal SCC and in 82 of 106 (77.4%) esophageal adenocarcinoma.

CONCLUSION: The combinations of curcumin, EGCG and lovastatin were able to suppress esophageal cancer cell growth in vitro and in nude mouse xenografts, these drugs also inhibited phosphorylated Erk1/2, c-Jun and COX-2 expression.

Anticancer and anti-inflammatory effects of cysteine metabolites of the green tea polyphenol, (-)-epigallocatechin-3-gallate

(-)-Epigallocatechin-3-gallate (EGCG) has been shown to have cancer preventive activity in vitro and in vivo. We have previously shown that EGCG can undergo conjugation to cysteine to form 2'-cysteinyl-EGCG and 2''-cysteinyl-EGCG. Studies of thiol-conjugated metabolites of methamphetamine indicate that such metabolites are not detoxified but retain biological activity. Here, we examined the growth inhibitory, pro-oxidant, and anti-inflammatory activities of the cysteine metabolites of EGCG. Both compounds dose-dependently inhibited the growth of colon cancer and intestinal cell lines. Both metabolites prevented aberrant arachidonic acid release and nitric oxide production by lipopolysaccharide-stimulated RAW264.7 cells. Under cell culture conditions, 2''-cysteinyl-EGCG produced H2O2 at a faster rate than EGCG. The results of the present study show that cysteine conjugates of EGCG retain the growth inhibitory, anti-inflammatory, and pro-oxidant activities of EGCG in vitro and may play a role in disease prevention in vivo. These results remain to be confirmed in vivo.

N-Acetylcysteine enhances the lung cancer inhibitory effect of epigallocatechin-3-gallate and forms a new adduct

The major tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), inhibits carcinogenesis in many in vivo models. Many potential mechanisms of action have been proposed based on cell line studies, including prooxidant activity. In the present study, we studied the effect of N-acetylcysteine (NAC) on the inhibitory effects of EGCG on lung cancer cell growth. We found that NAC (0-2 mM) dose dependently enhanced the growth inhibitory activity of EGCG against murine and human lung cancer cells. The combination of NAC and EGCG caused an 8.8-fold increase in apoptosis in CL13 mouse lung cancer cells compared to treatment with either agent alone. Addition of 2 mM NAC increased the stability of EGCG in the presence of CL13 cells (t 1/2=8.5 h vs 22.7 h). Intracellular levels of EGCG were increased 5.5-fold by the addition of 2 mM NAC. HPLC and LC-MS analyses of cell culture medium from CL13 cells treated with EGCG and NAC for 24 h revealed that EGCG-2'-NAC was time dependently formed. This adduct was not formed in the absence of NAC. The present results show that under cell culture conditions, EGCG and NAC interact to form a previously unreported adduct, EGCG-2'-NAC, which may contribute to enhancement of EGCG-mediated cell killing.