Green tea catechin, Epigallocatechin-3-gallate (EGCG): Mechanisms, perspectives and clinical applications

Department of Pharmacology, Toxicology and Therapeutics, and Medicine, The University of Kansas Cancer Center, The University of Kansas Medical Center, Kansas City, KS 66160, United States.
Biochemical pharmacology (Impact Factor: 5.01). 07/2011; 82(12):1807-21. DOI: 10.1016/j.bcp.2011.07.093
Source: PubMed


An expanding body of preclinical evidence suggests EGCG, the major catechin found in green tea (Camellia sinensis), has the potential to impact a variety of human diseases. Apparently, EGCG functions as a powerful antioxidant, preventing oxidative damage in healthy cells, but also as an antiangiogenic and antitumor agent and as a modulator of tumor cell response to chemotherapy. Much of the cancer chemopreventive properties of green tea are mediated by EGCG that induces apoptosis and promotes cell growth arrest by altering the expression of cell cycle regulatory proteins, activating killer caspases, and suppressing oncogenic transcription factors and pluripotency maintain factors. In vitro studies have demonstrated that EGCG blocks carcinogenesis by affecting a wide array of signal transduction pathways including JAK/STAT, MAPK, PI3K/AKT, Wnt and Notch. EGCG stimulates telomere fragmentation through inhibiting telomerase activity. Various clinical studies have revealed that treatment by EGCG inhibits tumor incidence and multiplicity in different organ sites such as liver, stomach, skin, lung, mammary gland and colon. Recent work demonstrated that EGCG reduced DNMTs, proteases, and DHFR activities, which would affect transcription of TSGs and protein synthesis. EGCG has great potential in cancer prevention because of its safety, low cost and bioavailability. In this review, we discuss its cancer preventive properties and its mechanism of action at numerous points regulating cancer cell growth, survival, angiogenesis and metastasis. Therefore, non-toxic natural agent could be useful either alone or in combination with conventional therapeutics for the prevention of tumor progression and/or treatment of human malignancies.

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    • "Tea is one of the most highly consumed beverages in the world and is rich in compounds exhibiting multiple health benefits (reviewed in [108]). The pharmacological action of tea is mainly attributed to large quantities of polyphenolic compounds known as catechins, which include epicatechin (EC), epigallocatechin (EGC), epicatechin-3-gallate (ECG), and epigallocatechin-3-gallate (EGCG) particularly in green tea and thearubigin and theaflavins in black tea. "
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    ABSTRACT: Deregulation of angiogenesis – the growth of new blood vessels from an existing vasculature – is a main driving force in many severe human diseases including cancer. As such, tumor angiogenesis is important for delivering oxygen and nutrients to growing tumors, and therefore considered an essential pathologic feature of cancer, while also playing a key role in enabling other aspects of tumor pathology such as metabolic deregulation and tumor dissemination/metastasis. Recently, inhibition of tumor angiogenesis has become a clinical anti-cancer strategy in line with chemotherapy, radiotherapy and surgery, which underscore the critical importance of the angiogenic switch during early tumor development. Unfortunately the clinically approved anti-angiogenic drugs in use today are only effective in a subset of the patients, and many who initially respond develop resistance over time. Also, some of the anti-angiogenic drugs are toxic and it would be of great importance to identify alternative compounds, which could overcome these drawbacks and limitations of the currently available therapy. Finding “the most important target” may, however, prove a very challenging approach as the tumor environment is highly diverse, consisting of many different cell types, all of which may contribute to tumor angiogenesis. Furthermore, the tumor cells themselves are genetically unstable, leading to a progressive increase in the number of different angiogenic factors produced as the cancer progresses to advanced stages. As an alternative approach to targeted therapy, options to broadly interfere with angiogenic signals by a mixture of non-toxic natural compound with pleiotropic actions were viewed by this team as an opportunity to develop a complementary anti-angiogenesis treatment option. As a part of the “Halifax Project” within the “Getting to know cancer” framework, we have here, based on a thorough review of the literature, identified 10 important aspects of tumor angiogenesis and the pathological tumor vasculature which would be well suited as targets for anti-angiogenic therapy: (1) endothelial cell migration/tip cell formation, (2) structural abnormalities of tumor vessels, (3) hypoxia, (4) lymphangiogenesis, (5) elevated interstitial fluid pressure, (6) poor perfusion, (7) disrupted circadian rhythms, (8) tumor promoting inflammation, (9) tumor promoting fibroblasts and (10) tumor cell metabolism/acidosis. Following this analysis, we scrutinized the available literature on broadly acting anti-angiogenic natural products, with a focus on finding qualitative information on phytochemicals which could inhibit these targets and came up with 10 prototypical phytochemical compounds: (1) oleic acid, (2) tripterine, (3) silibinin, (4) curcumin, (5) epigallocatechin-gallate, (6) kaempferol, (7) melatonin, (8) enterolactone, (9) withaferin A and (10) resveratrol. We suggest that these plant-derived compounds could be combined to constitute a broader acting and more effective inhibitory cocktail at doses that would not be likely to cause excessive toxicity. All the targets and phytochemical approaches were further cross-validated against their effects on other essential tumorigenic pathways (based on the “hallmarks” of cancer) in order to discover possible synergies or potentially harmful interactions, and were found to generally also have positive involvement in/effects on these other aspects of tumor biology. The aim is that this discussion could lead to the selection of combinations of such anti-angiogenic compounds which could be used in potent anti-tumor cocktails, for enhanced therapeutic efficacy, reduced toxicity and circumvention of single-agent anti-angiogenic resistance, as well as for possible use in primary or secondary cancer prevention strategies.
    Seminars in Cancer Biology 11/2015; 35(Supplement):S224-S243. DOI:10.1016/j.semcancer.2015.01.001 · 9.33 Impact Factor
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    • "PLGA based polymeric nanoparticles are studied to enhance the biological activity, water solubility, and bioavailability of various drug and natural products because of their small particle size and large surface area [10]. For instance, Singh et al. showed that tea polyphenol loaded PLGA nanoparticles provide 30-fold higher prevention on the DNA damage than free tee polyphenols [26]. Chaowanachan et al. synthesized efavirenz loaded PLGA nanoparticles and researcher showed that the HIV inhibitory effect of nanoparticle showed up to a 50-fold reduction in the 50% inhibitory concentration (IC 50 ) compared to free drug [27]. "
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    ABSTRACT: CAPE loaded PLGA nanoparticles were prepared using the oil in water (o/w) single emulsion solvent evaporation methods. Five different processing parameters including initial CAPE amount, initial PLGA amount, PVA concentration in aqueous phase, PVA volume, and solvent type were screened systematically to improve encapsulation of hydrophobic CAPE molecule, simultaneously minimize particle size, and raise the reaction yield. Obtained results showed that the encapsulation efficiency of the nanoparticles significantly increased with the increase of the initial CAPE amount ( p < 0.05 ) and particle size ( p < 0.05 ). Furthermore, the particle size is significantly influenced by initial polymer amount ( p < 0.05 ) and surfactant concentration ( p < 0.05 ). By the optimization of process parameters, the nanoparticles produced 70 ± 6 % reaction yield, 89 ± 3 % encapsulation efficiency, - 34.4 ± 2.5 mV zeta potential, and 163 ± 2 nm particle size with low polydispersity index 0.119 ± 0.002 . The particle size and surface morphology of optimized nanoparticles were studied and analyses showed that the nanoparticles have uniform size distribution, smooth surface, and spherical shape. Lyophilized nanoparticles with different CAPE and PLGA concentration in formulation were examined for in vitro release at physiological pH. Interestingly, the optimized nanoparticles showed a high (83.08%) and sustained CAPE release (lasting for 16 days) compared to nonoptimized nanoparticle.
    Journal of Nanomaterials 10/2015; 2015(10):1-12. DOI:10.1155/2015/341848 · 1.64 Impact Factor
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    • "mg/g dry weight with polar solvents (Beevi et al. 2012). These components, including catechin, have been found to control metabolic disorders, possibly by reducing inflammation via their antioxidant properties (Singh et al. 2011). Fig. 4 "

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