Epigallocatechin Gallate Derivatives Research Articles

Synthesis of prodelphinidin B2 3,3′′-digallate using AgOTf-mediated self-condensation

The Lewis acid mediated self-condensation of an epigallocatechin gallate derivative was examined. We found that AgOTf as a Lewis acid and diethylene glycol as a leaving group at C-4 position afforded a dimeric epigallocatechin gallate derivative in a moderate yield. The condensed product was applied to the synthesis of prodelphinidin B2 3,3′′-digallate.

Epigallocatechin Gallate Derivative Y6 Reverses Oxaliplatin Resistance in Hepatocellular Carcinoma via Targeting the MiR-338-3p/HIF-1α/TWIST Axis to Inhibit EMT.

The emergence of drug resistance to oxaliplatin (OXA) is one of the critical obstacles in the therapy of advanced Hepatocellular Carcinoma (HCC). As an ethyl derivative of the natural compound epigallocatechin gallate (epigallocatechin-3-gallate, EGCG), Y6 was found to be able to enhance the sensitivity of HCC cells to doxorubicin. This study aimed to investigate the effect of Y6 on oxaliplatin resistance in HCC. MTT was used to determine the reversal effect of Y6 on OXA resistance. To further explore the reversal mechanism, we treated OXA alone or in combination with Y6 or EGCG in drugresistant cells and observed the morphological changes of the cells. At the same time, transwell assay was used to detect the invasion and migration ability of cells. Moreover, Real-time PCR and Western blot analysis were performed to determine the expression levels of the miR-338-3p gene, HIF-1α/Twist proteins, and EMT-related proteins. We found that Y6 could inhibit the proliferation of HCC cells and effectively reverse the drug resistance of oxaliplatin-resistant human liver cancer cells (SMMC-7721/OXA) to OXA, and the reversal effect was more significant than that of its lead drug EGCG. Most of the cells in the control group and OXA group showed typical mesenchymal-like cell morphology, while most of the cells in co-administration groups showed typical epithelioid cell morphology, and the ability of the cells to invade and migrate decreased dramatically, particularly in Y6 plus OXA group. At the same time, Y6 could up-regulate the EMT epithelial marker protein E-cadherin and down-regulate the interstitial marker protein Vimentin. In addition, in co-administration groups, the expression of miR-338-3p was up-regulated, while the expression of HIF-1α and Twist was down-regulated. Y6 significantly enhanced the susceptibility of drug-resistant cells to OXA, and the process may be related to the regulation of miR-338-3p/HIF-1α / TWIST pathway to inhibit EMT. Therefore, Y6 could be considered an effective medication resistance reversal agent, which could improve the therapeutic effect for hepatocellular cancer patients.

Comprehensive Review of EGCG Modification: Esterification Methods and Their Impacts on Biological Activities.

Epigallocatechin gallate (EGCG), the key constituent of tea polyphenols, presents challenges in terms of its lipid solubility, stability, and bioavailability because of its polyhydroxy structure. Consequently, structural modifications are imperative to enhance its efficacy. This paper comprehensively reviews the esterification techniques applied to EGCG over the past two decades and their impacts on bioactivities. Both chemical and enzymatic esterification methods involve catalysts, solvents, and hydrophobic groups as critical factors. Although the chemical method is cost-efficient, it poses challenges in purification; on the other hand, the enzymatic approach offers improved selectivity and simplified purification processes. The biological functions of EGCG are inevitably influenced by the structural changes incurred through esterification. The antioxidant capacity of EGCG derivatives can be compromised under certain conditions by reducing hydroxyl groups, while enhancing lipid solubility and stability can strengthen their antiviral, antibacterial, and anticancer properties. Additionally, esterification broadens the utility of EGCG in food applications. This review provides critical insights into developing cost-effective and environmentally sustainable selective esterification methods, as well as emphasizes the elucidation of the bioactive mechanisms of EGCG derivatives to facilitate their widespread adoption in food processing, healthcare products, and pharmaceuticals.

Improved antioxidative and antibacterial activity of epigallocatechin gallate derivative complexed by zinc cations and chitosan.

Epigallocatechin gallate (EGCG) has attracted increasing attention thanks to its multi-bioactivities, and people are keen on improving the antioxidative and antibacterial performance of EGCG. Based on the favorable biofunctionality of Zn2+ and chitosan (CS), an EGCG derivative with a novel formula, i.e., EGCG-Zn-CS, is presented in this study. The structure of EGCG-Zn-CS was characterized by FT-IR, UV-vis, TGA, XPS, and SEM-EDS. The radical elimination results indicate that 0.1 mg mL-1 of EGCG-Zn-CS demonstrates DPPH radical and hydroxyl radical scavenging activities of 94.8% and 92.3%, while 0.1 mg mL-1 of EGCG exhibits only 78.5% and 75.6%, respectively, which means improved antioxidative activity of EGCG-Zn-CS was obtained. Inhibitory experiments against Staphylococcus aureus and Escherichia coli reveal that the minimal inhibitory concentrations (MICs) of EGCG-Zn-CS were 15.625 μg mL-1 and 187.5 μg mL-1, whereas the minimal bactericide concentrations (MBCs) were 46.875 μg mL-1 and 750 μg mL-1, respectively, which indicate that EGCG-Zn-CS exerts much higher antibacterial activity than EGCG. It can be concluded that the complexing of zinc cations and CS could amazingly improve both the antioxidative and antibacterial activity of EGCG, and it is expected that an exploration of EGCG-Zn-CS may inspire the development of simultaneous effective antioxidant and antibacterial agents.

An EGCG Derivative in Combination with Nimotuzumab for the Treatment of Wild-Type EGFR NSCLC.

Inhibiting the tyrosine kinase activity of epidermal growth factor receptor (EGFR) using small-molecule tyrosine kinase inhibitors (TKIs) or monoclonal antibodies is often ineffective in treating cancers harboring wild-type EGFR. Given the fact that EGFR possesses a kinase-independent pro-survival function, more effective inhibition of EGFR-mediated signals is therefore necessary. In this study, we investigated the effects of using a combination of low-dose nimotuzumab and theasinensin A to evaluate whether the inhibitory effect of nimotuzumab on NCI-H441 cancer cells was enhanced. Here, theasinensin A, a novel epigallocatechin-3-gallate (EGCG) derivative, was identified and its potent anticancer activity against wild-type EGFR NSCLC was demonstrated in vitro; the anticancer activity was induced through degradation of EGFR. Mechanistic studies further revealed that theasinensin A bound directly to the EGFR extracellular domain, which decreased interaction with its ligand EGF in combination with nimotuzumab. Theasinensin A significantly promoted EGFR degradation and repressed downstream survival pathways in combination with nimotuzumab. Meanwhile, treatment with theasinensin A and nimotuzumab prevented xenograft growth, whereas the single agents had limited effect. Thus, the combination therapy of theasinensin A with nimotuzumab is a powerful candidate for treatment of wild-type EGFR cancers.

Characterization of two O-methyltransferases involved in the biosynthesis of O-methylated catechins in tea plant

Tea is known for having a high catechin content, with the main component being (−)-epigallocatechin gallate (EGCG), which has significant bioactivities, including potential anti-cancer and anti-inflammatory activity. The poor intestinal stability and permeability of EGCG, however, undermine these health-improving benefits. O-methylated EGCG derivatives, found in a few tea cultivars in low levels, have attracted considerable interest due to their increased bioavailability. Here, we identify two O-methyltransferases from tea plant: CsFAOMT1 that has a specific O-methyltransferase activity on the 3ʹʹ-position of EGCG to generate EGCG3′′Me, and CsFAOMT2 that predominantly catalyzes the formation of EGCG4″Me. In different tea tissues and germplasms, the transcript levels of CsFAOMT1 and CsFAOMT2 are strongly correlated with the amounts of EGCG3ʹʹMe and EGCG4ʹʹMe, respectively. Furthermore, the crystal structures of CsFAOMT1 and CsFAOMT2 reveal the key residues necessary for 3ʹʹ- and 4ʹʹ-O-methylation. These findings may provide guidance for the future development of tea cultivars with high O-methylated catechin content.

The polyphenol EGCG directly targets intracellular amyloid-β aggregates and promotes their lysosomal degradation.

The accumulation of amyloidogenic protein aggregates in neurons is a pathogenic hallmark of a large number of neurodegenerative diseases including Alzheimer's disease (AD). Small molecules targeting such structures and promoting their degradation may have therapeutic potential for the treatment of AD. Here, we searched for natural chemical compounds that decrease the abundance of stable, proteotoxic β-sheet-rich amyloid-β (Aβ) aggregates in cells. We found that the polyphenol (-)-epigallocatechin gallate (EGCG) functions as a potent chemical aggregate degrader in SH-EP cells. We further demonstrate that a novel, fluorescently labeled EGCG derivative (EGC-dihydroxybenzoate (DHB)-Rhodamine) also shows cellular activity. It directly targets intracellular Aβ42 aggregates and competes with EGCG for Aβ42 aggregate binding in vitro. Mechanistic investigations indicated a lysosomal accumulation of Aβ42 aggregates in SH-EP cells and showed that lysosomal cathepsin activity is critical for efficient EGCG-mediated aggregate clearance. In fact, EGCG treatment leads to an increased abundance of active cathepsin B isoforms and increased enzymatic activity in our SH-EP cell model. Our findings suggest that intracellular Aβ42 aggregates are cleared through the endo-lysosomal system. We show that EGCG directly targets intracellular Aβ42 aggregates and facilitates their lysosomal degradation. Small molecules, which bind to protein aggregates and increase their lysosomal degradation could have therapeutic potential for the treatment of amyloid diseases.

Mitochondria-targeting EGCG derivatives protect H9c2 cardiomyocytes from H2O2-induced apoptosis: design, synthesis and biological evaluation.

Pathologies related to cardiovascular diseases mostly emerge as a result of oxidative stress buildup in cardiomyocytes. The heavy load of mitochondrial oxidative phosphorylation in cardiac tissues corresponds to a surge in oxidative stress leading to mitochondrial dysfunction and cellular apoptosis. Thus, scavenging the reactive oxygen species (ROS) linked to mitochondria can significantly improve cardio-protection. Epigallocatechin-3-gallate (EGCG), the major polyphenol found in green tea has been extensively studied for its profound health-beneficial activities. Herein, we designed and synthesized a series of mitochondrial-targeting EGCG derivatives, namely MitoEGCGn (n = 4, 6, 8) by incorporating triphenylphosphonium ion onto it using different linkers. MitoEGCGn were found to be non-toxic to H9c2 rat cardiomyocyte cells even at higher doses in comparison to its parent molecule EGCG. Interestingly, MitoEGCG4 and MitoEGCG6 protected the H9c2 cardiomyocyte cells from the oxidative damage induced by H2O2 whereas EGCG was found to be toxic and ineffective in protecting the cells from H2O2 damage. MitoEGCG4 and MitoEGCG6 also protected the cells from the H2O2-induced disruption of mitochondrial membrane potential as well as activation of apoptosis as revealed by pro-caspase 3 expression profile, DNA fragmentation assay, and AO/EtBr staining. Taken together, our study shows that the mitochondria targeting EGCG derivatives were able to effectively combat the H2O2-induced oxidative stress in H9c2 cardiomyocytes. They eventually augmented the mitochondrial health of cardiomyocytes by maintaining the mitochondrial function and attenuating apoptosis. Overall, MitoEGCG4 and MitoEGCG6 could provision a cardioprotective role to H9c2 cardiomyocytes at the time of oxidative insults related to mitochondrial dysfunction-associated injuries.

Enzymatic Synthesis and Antioxidant Activity of Mono- and Diacylated Epigallocatechin Gallate and Related By-Products.

Ester derivatives of epigallocatechin gallate (EGCG) were enzymatically prepared by one-step transesterification with vinyl fatty acids consisting of varying acyl groups ranging from 2 to 18 carbon atoms (acetate, butyrate, caproate, caprylate, caprate, laurate, myristate, and stearate). The main acylation products were EGCG monoesters and diesters. However, due to the presence of trace amounts of water in the reaction medium, minor but noticeable hydrolysis of EGCG also occurred as a side reaction which required a prolonged purification process due to the formation of by-products such as gallic acid, epigallocatechin, and their esters. In this contribution, 8 EGCG monoesters, 7 EGCG diesters, and 7 gallic acid monoesters were isolated and purified, and the acylation positions were characterized. Meanwhile, several classical chemicals (DPPH, ABTS, FRAP, and Fe2+ chelation assays), food (β-carotene bleaching assay), and biological (LDL and DNA oxidation assays) models were conducted to evaluate and systematically compare their antioxidant efficacy. The lipophilicity of the EGCG derivatives increased with the increasing chain length of the acyl group and led to the fluctuation of their antioxidant efficacies. Three main factors, namely, the reduction potential, the partition coefficient of solute in the solvent system, and the steric hindrance of antioxidant agent and related substrates were considered to help explain the biased antioxidant performance of EGCG derivatives upon acylation modification. The results strongly suggest that the acylated EGCGs have great potential as lipophilic alternatives to the water-soluble EGCG in lipid-based matrices.

Structure-based design and synthesis of a novel long-chain 4''-alkyl ether derivative of EGCG as potent EGFR inhibitor: in vitro and in silico studies.

Herein, we report the discovery of a novel long-chain ether derivative of (−)-epigallocatechin-3-gallate (EGCG), a major green tea polyphenol as a potent EGFR inhibitor. A series of 4′′-alkyl EGCG derivatives have been synthesized via regio-selectively alkylating the 4′′ hydroxyl group in the D-ring of EGCG and tested for their antiproliferative activities against high (A431), moderate (HeLa), and low (MCF-7) EGFR-expressing cancer cell lines. The most potent compound, 4′′-C14 EGCG showed the lowest IC50 values across all the tested cell lines. 4′′-C14 EGCG was also found to be significantly more stable than EGCG under physiological conditions (PBS at pH 7.4). Further western blot analysis and imaging data revealed that 4′′-C14 EGCG induced cell death in A431 cells with shrunken nuclei, nuclear fragmentation, membrane blebbing, and increased population of apoptotic cells where BAX upregulation and BCLXL downregulation were observed. In addition, autophosphorylation of EGFR and its downstream signalling proteins Akt and ERK were markedly inhibited by 4′′-C14 EGCG. MD simulation and the MM/PBSA analysis disclosed the binding mode of 4′′-C14 EGCG in the ATP-binding site of EGFR kinase domain. Taken together, our findings demonstrate that 4′′-C14 EGCG can act as a promising potent EGFR inhibitor with enhanced stability.

Epigallocatechin Gallate (EGCG) – A Novel Covalent NF- κB Inhibitor: Structural and Molecular Characterization

Tea contains antioxidant catechins thought to exert health-promoting protective effects against conditions involving chronic inflammation, such as cardiovascular diseases. The most abundant catechin in tea is Epigallocatechin Gallate (EGCG), thought to be a key contributor to tea’s health-promoting actions. EGCG exerts protective cardiovascular effects via its antioxidant, antiinflammatory, hypolipidemic, anti-thrombogenic, and anti-hypertensive actions. Because EGCG inhibits the strong proinflammatory gene-inducing transcription factor NF-κB, we analyzed the chemical and molecular details of the mechanism by which EGCG mediates NF-κB inhibition. We quantified and mapped key parameters of its chemical reactivity including its electrophilic Fukui ƒ+ function, in silico covalent binding, and identified its frontier Molecular Orbitals (MOs) and nucleophilic susceptibility. These physical and chemical reactivity parameters revealed that the bond-forming MOs are distributed on the B ring of the EGCG oxidized state with nucleophilic susceptibility, and that this B ring has properties that favor participating in a Cys-alkylating 1,4-addition reaction. Molecular modeling and docking analysis further revealed that EGCG bonds covalently with Cys-38 of NF-κB-p65, and thereby inhibits its DNA binding ability. We also generated a model pharmacophore based on the EGCG-NF-κB complex. We conclude that EGCG covalently binds to NF-κB-p65 and inhibits it by abolishing its DNA binding, by chemical mechanisms that may inform design of EGCG derivatives as novel anti-inflammatory agents.

Antioxidant activities of lipophilic (−)-epigallocatechin gallate derivatives in vitro and in lipid-based food systems

The low lipophilicity of (−)-epigallocatechin gallate (EGCG) significantly limits its applications in lipophilic systems. Herein, EGCG was acylated with vinyl esters of different carbon chain lengths under the action of the lipase Novozym 435. Five EGCG derivatives (C2-EGCG, C4-EGCG, C6-EGCG, C8-EGCG, and C12-EGCG) with different lipophilicities were obtained, and their antioxidant activities were evaluated. Due to the loss of the phenolic hydroxyl group of EGCG, the capacities of these derivatives to scavenge the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS+•), 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•), and hydroxyl radical (•OH) were lower than those of EGCG. In a homogeneous oil system, the antioxidant capacities of the EGCG derivatives were higher than that of EGCG. Upon increasing the lipophilicities of the derivatives, the antioxidant activities initially increased and later decreased, thus demonstrating the “cut-off effect.” Among the various derivatives, C8-EGCG possessed the highest antioxidant activity. In the oil-in-water emulsions, optimum antioxidant activity was observed for short carbon chain length (C2-EGCG). This study therefore provides useful information regarding the design of EGCG applications in food lipid systems.

Synthesis, Stability, and Antidiabetic Activity Evaluation of (-)-Epigallocatechin Gallate (EGCG) Palmitate Derived from Natural Tea Polyphenols.

This work describes a novel approach for the synthesis of (−)-epigallocatechin gallate (EGCG) palmitate by a chemical-synthesis method, where the elevated stability of the EGCG derivative is achieved. Various parameters affecting the acylation process, such as the base, solvent, as well as the molar ratio of palmitoyl chloride, have been studied to optimize the acylation procedure. The optimized reaction condition was set as follows: EGCG/palmitoyl chloride/sodium acetate was under a molar ratio of 1:2:2, with acetone as the solvent, and the reaction temperature was 40 °C. Under the optimized condition, the yield reached 90.6%. The EGCG palmitate (PEGCG) was isolated and identified as 4′-O-palmitoyl EGCG. Moreover, the stability of PEGCG under different conditions was proved significantly superior to EGCG. Finally, PEGCG showed better inhibition towards α-amylase and α-glucosidase, which was 4.5 and 52 times of EGCG, respectively. Molecular docking simulations confirmed the in vitro assay results. This study set a novel and practical synthetic approach for the derivatization of EGCG, and suggest that PEGCG may act as an antidiabetic agent.

Improved Stability and Targeted Cytotoxicity of Epigallocatechin-3-Gallate Palmitate for Anticancer Therapy.

Although with high antioxidant activity, epigallocatechin-3-gallate (EGCG) was restricted by its poor chemical stability in practical applications. One of EGCG derivatives, EGCG palmitate, was synthesized with EGCG and palmitoyl chloride to overcome instability of EGCG. However, uncertainties still exist in chemical stability and cytotoxicity of EGCG palmitate, which are essential for further exploration in anticancer therapy. Our work aims to analyze the resistance of EGCG palmitate to oxidation and summarize its targeted inhibition efficiency on cancerous cells and normal cells. High-performance liquid chromatography analysis confirmed that EGCG palmitate remained stable in air and Dulbecco's modified eagle medium (DMEM) for a longer time than EGCG. Antioxidative and pro-oxidative effects of EGCG palmitate on treated cells are proposed through reactive oxygen species (ROS) detection, respectively. It reveals that pro-oxidants by H2O2 production can exert antiproliferative and proapoptotic effects on cancerous cells and stimulate autophagy, while an antioxidant relieves oxidative stress caused by superoxide as compared to normal cells. Consequently, targeted cytotoxicity is adopted by EGCG palmitate-treated cancerous cells. Results above manifest that EGCG palmitate possesses potential to serve as a promising prodrug in anticancer treatment.

The epigallocatechin gallate derivative Y6 reduces the cardiotoxicity and enhances the efficacy of daunorubicin against human hepatocellular carcinoma by inhibiting carbonyl reductase 1 expression

Ethnopharmacological relevanceGreen tea is the most ancient and popular beverage worldwide and its main constituent epigallocatechin-3-gallate (EGCG) has a potential role in the management of cancer through the modulation of cell signaling pathways. However, EGCG is frangible to oxidation and exhibits low lipid solubility and bioavailability, and we synthesized a derivative of EGCG in an attempt to overcome these limitations. Aim of the studyThe anthracycline antibiotic daunorubicin (DNR) is a potent anticancer agent. However, its severe cardiotoxic limits its clinical efficacy. Human carbonyl reductase 1 (CBR1) is one of the most effective human reductases for producing hydroxyl metabolites and thus may be involved in increasing the cardiotoxicity and decreasing the antineoplastic effect of anthracycline antibiotics. Accordingly, in this study, we investigated the co-therapeutic effect of Y6, a novel and potent adjuvant obtained by optimization of the structure of EGCG. Material and methodsThe cellular concentrations of DNR and its metabolite DNRol were measured by HPLC to determine the effects of EGCG and Y6 on the inhibition of DNRol formation. The cytotoxic effects of EGCG and Y6 were tested by MTT assay in order to identify non-toxic concentrations of them. To understand their antitumor and cardioprotective mechanisms, hypoxia-inducible factor-1α (HIF-1α) and CBR1 protein expression was measured via Western blotting and immunohistochemical staining while gene expression was analyzed using RT-PCR. Moreover, PI3K/AKT and MEK/ERK signaling pathways were analyzed via Western blotting. HepG2 xenograft model was used to detect the effects of EGCG and Y6 on the antitumor activity and cardiotoxicity of DNR in vivo. Finally, to obtain further insight into the interactions of Y6 and EGCG with HIF-1α and CBR1, we performed a molecular modeling. ResultsY6(10 μg/ml or 55 mg/kg) decreased the expression of HIF-1α and CBR1 at both the mRNA and protein levels during combined drug therapy in vitro as well as in vivo, thereby inhibiting formation of the metabolite DNRol from DNR, with the mechanisms being related to PI3K/AKT and MEK/ERK signaling inhibition. In a human carcinoma xenograft model established with subcutaneous HepG2 cells, Y6(55 mg/kg) enhanced the antitumor effect and reduced the cardiotoxicity of DNR more effectively than EGCG(40 mg/kg). ConclusionsY6 has the ability to inhibit CBR1 expression through the coordinate inhibition of PI3K/AKT and MEK/ERK signaling, then synergistically enhances the antitumor effect and reduces the cardiotoxicity of DNR.

The epigallocatechin gallate derivative Y6 inhibits human hepatocellular carcinoma by inhibiting angiogenesis in MAPK/ERK1/2 and PI3K/AKT/ HIF-1α/VEGF dependent pathways

Ethnopharmacological relevanceHypervascularity has been considered as one of the major features of many solid tumors. Green tea is one of the commonly drink resources in China, and its active component, Epigallocatechin gallate (EGCG), exhibits antiangiogenic activities in various experimental tumor models. However, EGCG has many shortages, e.g., relatively unstable, low lipid solubility, poor bioavailability, and short duration of action. Aim of the studyTo overcome the shortages of EGCG for antiangiogenic antitumor usage, our study developed a novel EGCG derivate, Y6(5,3′,4′,3″,4″,5″-6-0-ethyl-EGCG). The underlying mechanism was also elucidated. Material and methodswe evaluated the effects of EGCG, Y6 on HCC and angiogenesis in vivo and in vitro. Moreover, to understand their antitumor mechanisms, key factors within angiogenesis-related signaling pathways (MAPK/ERK1/2, PI3K/AKT, HIF-1 VEGF) were analyzed by using western blot, immunohistochemistry (IHC), quantitative real-time quantitative PCR (RT-PCR). HepG2 xenograft model and the chorioallantoic membrane (CAM) were used to investigate the effects of Y6 and EGCG on tumors and anti-angiogenesis in vivo. Micro-vessel density (MVD) was analyzed by IHC of CD34 staining. IHC, qRT-PCR and Western blot were used to detect the expression of HIF-1α and VEGF protein in tumor tissues. The protein levels of MAPK/ERK1/2, PI3K/AKT, HIF-1α, and VEGF in tumor tissues were detected by western blot. ResultsOur results demonstrated that both EGCG and Y6 displayed antiangiogenetic and antitumor effects against HCC cells in vitro and in vivo. We found that rather than equal amount of EGCG, Y6 displayed better abilities in inhibiting the growth of HCC tumor cells, as well as inhibiting the growth of neovascularization in the chick embryos and HepG2 xenograft tumors bearing-mice, based on the data obtained from MTT assay, immunohistochemistry (IHC), chick chorioallantoic membrane (CAM) assays. In the comparison of equivalent dose of EGCG, qRT-PCR data showed that Y6 induced more significant decrease of the mRNA levels of HIF-1α and VEGF in supernatant-treated SMMC-7721 cells under hypoxic condition, as well as in the in xenograft tumor tissues; whereas Y6 also significantly reduced the protein levels of MAPK/ERK1/2, PI3K/AKT, HIF-1α, and VEGF to a greater extent than EGCG, determined by western blotting assay. Conclusionsour work suggests that the new EGCG derivate Y6 could significantly inhibit tumor growth and angiogenesis which is possibly involved with the signaling intervention of MAPK/ERK1/2 and PI3K/AKT/HIF-1α/VEGF pathways, and is supposed to be a potential therapeutic reagent for anti-angiogenesis treatment of solid tumors.

A new epigallocatechin gallate derivative isolated from Anhua dark tea sensitizes the chemosensitivity of gefitinib via the suppression of PI3K/mTOR and epithelial-mesenchymal transition

The acquired resistance to gefitinib limits its clinical application. Epigallocatechin-3-gallate (EGCG) has been found to enhance the efficacy of gefitinib against resistant. However, the cellular and molecular mechanisms have not been completely illuminated in NSCLC. In this study, a new epigallocatechin gallate derivative (2R,3R-6-methoxycarbonylgallocatechin-3-O-gallate, the following referred to as EGCGD) (1) and three known epigallocatechin gallate compounds including epicatechin-3-O-gallate (2), gallocatechin-3-O-gallate (3) and epigallocatechin-3-O-gallate (4, EGCG) were isolated and identified from Anhua dark tea. The pharmacological studies showed EGCGD was more effective against gefitinib-resistant HCC827-Gef cells compared to that of other three epigallocatechin gallate compounds including EGCG, suggesting that introduction of 6-methoxycarbonyl to EGCG might enhance its antitumor activities. Further study on molecular mechanism showed EGCGD increased the potency of gefitinib against HCC827-Gef cells via suppression of epithelial-Mesenchymal transition (EMT) and dual inhibition of PI3K/mTOR.

Monoalkylated Epigallocatechin-3-gallate (C18-EGCG) as Novel Lipophilic EGCG Derivative: Characterization and Antioxidant Evaluation.

Epigallocatechin-3-gallate (EGCG) has the highest antioxidant activity compared to the others catechins of green tea. However, the beneficial effects are mainly limited by its poor membrane permeability. A derivatization strategy to increase the EGCG interaction with lipid membranes is considered as one feasible approach to expand its application in lipophilic media, in particular the cellular absorption. At this purpose the hydrophilic EGCG was modified by inserting an aliphatic C18 chain linked to the gallate ring by an ethereal bond, the structure determined by NMR (Nuclear Magnetic Resonance) and confirmed by Density Functional Theory (DFT) calculations. The in vitro antioxidant activity of the mono-alkylated EGCG (C18-EGCG) was studied by the DPPH and Thiobarbituric Acid Reactive Substances (TBARS) assays, and its ability to protect cells towards oxidative stress was evaluated in Adult Retinal Pigmented Epithelium (ARPE-19) cells. Molecular Dynamics (MD) simulation and liposomal/buffer partition were used to study the interaction of the modified and unmodified antioxidants with a cell membrane model: the combined experimental-in silico approach shed light on the higher affinity of C18-EGCG toward lipid bilayer. Although the DPPH assay stated that the functionalization decreases the EGCG activity against free radicals, from cellular experiments it resulted that the lipid moiety increases the antioxidant protection of the new lipophilic derivative.

Lipophilized Epigallocatechin Gallate Derivative Exerts Anti-Proliferation Efficacy through Induction of Cell Cycle Arrest and Apoptosis on DU145 Human Prostate Cancer Cells.

Epigallocatechin gallate (EGCG) is the predominant tea polyphenol and it exhibits a hydrophilic character. The lipophilized EGCG derivative (LEGCG) was synthesized by enzymatic esterification of EGCG with lauric acid to enhance its bioactivity. The tetralauroyl EGCG was confirmed by high-performance liquid chromatography-tandem mass spectrometry and further identified as 3′, 5′, 3″, 5″-4-O-lauroyl EGCG by 1H and 13C nuclear magnetic resonance. The anti-proliferation effect of LEGCG on DU145 human prostate carcinoma cells was evaluated by MTT assay. In addition, the underlying molecular mechanism by which LEGCG exerts anti-proliferation efficacy was elucidated by flow cytometry and immunoblot analysis. Results suggested that LEGCG exhibited a dose-dependent anti-proliferation effect on DU145 cells by G0/G1 phase arrest and induction of apoptosis. LEGCG induced cell cycle arrest via p53/p21 activation, which down-regulated the cyclin D1 and CDK4 expression. In addition, LEGCG induced apoptosis by increasing the Bax/Bcl-2 ratio, the cytochrome c release, and the caspases cleavage on DU145 cells. The results provide theoretical support to prevent prostate cancer with LEGCG.

Photoprotective effects of 2S,3R-6-methoxycarbonylgallocatechin isolated from Anhua dark tea on UVB-induced inflammatory responses in human keratinocytes

Ultraviolet B (UVB) induces inflammation and causes skin aging. The signs of skin aging, such as wrinkles, discolored spots, loss of skin moisture, and disruption of the skin barrier, are mostly caused by inflammatory signaling among various skin layers. The cells on the outermost surface of the skin are keratinocytes; these cells protect the skin against environmental stress and play an important role in immunomodulation by secreting cytokines in response to environmental stress. In the present study, we found that UVB activates STAT1 to mediate inflammatory signaling, yet STAT1 (S272) and STAT (Y702) shows different responses against UVB exposure. Anhua drak tea is a post-fermented dark tea produced in Anhua and Xinhua country in Hunan province of China. Treatment with 2S,3R-6-methoxycarbonylgallocatechin (MCGE), an epigallocatechin gallate derivative isolated from black tea (Anhua dark tea), effectively suppresses STAT1 activation and inflammatory cytokines, and activates Nrf2 pathway to protect cells from reactive oxygen species production in UVB exposed keratinocyte cells (HaCaT). Interestingly, the effects of MCGE were independent on MAPK signaling pathway. Moreover, MCGE regulates inflammatory cytokines in monocyte-keratinocyte (THP-1, HaCaT) co-culture and macrophage differentiation models. These results suggest that MCGE potentially can be used as a photoprotective agent against UVB-induced inflammatory responses.