Neuroprotective Activity of (-)-Epigallocatechin Gallate against Lipopolysaccharide-Mediated Cytotoxicity. J Immunol Res. 2016;2016:4962351. [PMID: 27191001 PMCID: PMC4844887 DOI: 10.1155/2016/4962351]

Role of microglia in diabetic neuropathic pain

Approximately one-third of the patients with diabetes worldwide suffer from neuropathic pain, mainly categorized by spontaneous and stimulus-induced pain. Microglia are a class of immune effector cells residing in the central nervous system and play a pivotal role in diabetic neuropathic pain (DNP). Microglia specifically respond to hyperglycemia along with inflammatory cytokines and adenosine triphosphate produced during hyperglycemic damage to nerve fibers. Because of the presence of multiple receptors on the microglial surface, microglia are dynamically and highly responsive to their immediate environment. Following peripheral sensitization caused by hyperglycemia, microglia are affected by the cascade of inflammatory factors and other substances and respond accordingly, resulting in a change in their functional state for DNP pathogenesis. Inhibition of receptors such as P2X reporters, reducing cytokine expression levels in the microglial reactivity mechanisms, and inhibiting their intracellular signaling pathways can effectively alleviate DNP. A variety of drugs attenuate DNP by inhibiting the aforementioned processes induced by microglial reactivity. In this review, we summarize the pathological mechanisms by which microglia promote and maintain DNP, the drugs and therapeutic techniques available, and the latest advances in this field.

Application of In Situ Mucoadhesive Hydrogel with Anti-Inflammatory and Pro-Repairing Dual Properties for the Treatment of Chemotherapy-Induced Oral Mucositis

Chemotherapy-induced oral mucositis (CIOM) is a prevalent complication of chemotherapy and significantly affects the treatment process. However, effective treatment for CIOM is lacking due to the unique environment of the oral cavity and the single effect of current drug delivery systems. In this present study, we propose an innovative approach by combining a methacrylate-modified human recombinant collagen III (rhCol3MA) hydrogel system with hyaluronic acid-epigallocatechin gallate (HA-E) and dopamine-modified methacrylate-alginate (AlgDA-MA). HA-E is used as an antioxidant and anti-inflammatory agent and synergizes with AlgDA-MA to improve the wet adhesion of hydrogel. The results of rhCol3MA/HA-E/AlgDA-MA (Col/HA-E/Alg) hydrogel demonstrate suitable physicochemical properties, excellent wet adhesive capacity, and biocompatibility. Notably, the hydrogel could promote macrophage polarization from M1 to M2 and redress human oral keratinocyte (HOK) inflammation by inhibiting NF-κB activation. Wound healing evaluations in vivo demonstrate that the Col/HA-E/Alg hydrogel exhibits a pro-repair effect by mitigating inflammatory imbalances, fostering early angiogenesis, and facilitating collagen repair. In summary, the Col/HA-E/Alg hydrogel could serve as a promising multifunctional dressing for the treatment of CIOM.

Epigallocatechin Gallate: A Multifaceted Molecule for Neurological Disorders and Neurotropic Viral Infections

Epigallocatechin-3-gallate (EGCG), a polyphenolic moiety found in green tea extracts, exhibits pleiotropic bioactivities to combat many diseases including neurological ailments. These neurological diseases include Alzheimer's disease, multiple sclerosis, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. For instance, in the case of Alzheimer's disease, the formation of a β-sheet in the region of the 10th-21st amino acids was significantly reduced in EGCG-induced oligomeric samples of Aβ40. Its interference induces the formation of Aβ structures with an increase in intercenter-of-mass distances, reduction in interchain/intrachain contacts, reduction in β-sheet propensity, and increase in α-helix. Besides, numerous neurotropic viruses are known to instigate or aggravate neurological ailments. It exerts an effect on the oxidative damage caused in neurodegenerative disorders by acting on GSK3-β, PI3K/Akt, and downstream signaling pathways via caspase-3 and cytochrome-c. EGCG also diminishes these viral-mediated effects, such as EGCG delayed HSV-1 infection by blocking the entry for virions, inhibitory effects on NS3/4A protease or NS5B polymerase of HCV and potent inhibitor of ZIKV NS2B-NS3pro/NS3 serine protease (NS3-SP). It showed a reduction in the neurotoxic properties of HIV-gp120 and Tat in the presence of IFN-γ. EGCG also involves numerous viral-mediated inflammatory cascades, such as JAK/STAT. Nonetheless, it also inhibits the Epstein-Barr virus replication protein (Zta and Rta). Moreover, it also impedes certain viruses (influenza A and B strains) by hijacking the endosomal and lysosomal compartments. Therefore, the current article aims to describe the importance of EGCG in numerous neurological diseases and its inhibitory effect against neurotropic viruses.

(-)-Epicatechin gallate prevents inflammatory response in hypoxia-activated microglia and cerebral edema by inhibiting NF-κB signaling

High-altitude cerebral edema (HACE), a potentially lethal disease, is associated with a time-dependent exposure to altitude-related hypobaric hypoxia (HH) and has reportedly been associated with microglia hyperactivation. Catechins are substances with good antioxidant properties, among which (-)-epigallocatechin gallate (EGCG) may play a neuroprotective role through the inhibition of microglia overactivation; however, the function of its analog- (-)-epicatechin gallate (ECG)-requires further elucidation. The aim of the present study was to investigate whether ECG prevented HACE by inhibiting HH-activated microglia. Primary microglia exposed to lipopolysaccharide (LPS)/ATP were co-treated with EGCG, ECG, and (-)-epigallocatechin, and ECG and EGCG exerted significant anti-inflammatory and neuroprotective effects. ECG inhibited the NF-κB pathway to prevent the activation of microglia induced by 1% O₂. In addition, ECG ameliorated the increase in brain water content and aquaporin 4 expression induced by HH in mice. ECG also reduced the number of Iba1⁺ microglia in the brain, the release of proinflammatory factors, and the recruitment of microglia to blood vessels in HH-exposed mice. The outcomes of the present study revealed that ECG alleviated hypoxic hyperactivated microglia, reduced the neuroinflammation and blood-brain barrier permeability, and prevented HACE by inhibiting NF-κB signaling.

Dietary Plant Polyphenols as the Potential Drugs in Neurodegenerative Diseases: Current Evidence, Advances, and Opportunities

Neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), are characterized by the progressive degeneration of neurons. Although the etiology and pathogenesis of neurodegenerative diseases have been studied intensively, the mechanism is still in its infancy. In general, most neurodegenerative diseases share common molecular mechanisms, and multiple risks interact and promote the pathologic process of neurogenerative diseases. At present, most of the approved drugs only alleviate the clinical symptoms but fail to cure neurodegenerative diseases. Numerous studies indicate that dietary plant polyphenols are safe and exhibit potent neuroprotective effects in various neurodegenerative diseases. However, low bioavailability is the biggest obstacle for polyphenol that largely limits its adoption from evidence into clinical practice. In this review, we summarized the widely recognized mechanisms associated with neurodegenerative diseases, such as misfolded proteins, mitochondrial dysfunction, oxidative damage, and neuroinflammatory responses. In addition, we summarized the research advances about the neuroprotective effect of the most widely reported dietary plant polyphenols. Moreover, we discussed the current clinical study and application of polyphenols and the factors that result in low bioavailability, such as poor stability and low permeability across the blood-brain barrier (BBB). In the future, the improvement of absorption and stability, modification of structure and formulation, and the combination therapy will provide more opportunities from the laboratory into the clinic for polyphenols. Lastly, we hope that the present review will encourage further researches on natural dietary polyphenols in the treatment of neurodegenerative diseases.

Effects of the psychoactive compounds in green tea on risky decision-making

Epigallocatechin-3-gallate (EGCG) and caffeine are the two primary compounds found in green tea. While EGCG has anxiolytic and anti-inflammatory effects, its acute effects on cognition are not well understood. Furthermore, despite widespread green tea consumption, little is known about how EGCG and caffeine co-administration impacts behavior. Here, we investigated the effects of multiple doses of either EGCG or caffeine on a rat model of risk-taking. This was assessed using the risky decision-making task (RDT), in which rats choose between a small, well-tolerated reward and a large reward with escalating risk of mild footshock. Rats were tested in RDT after acute systemic administration of EGCG, caffeine or joint EGCG and caffeine. EGCG caused a dose-dependent reduction in risk-taking without affecting reward discrimination or task engagement. Caffeine did not impact risk-taking, but elevated locomotor activity and reduced task engagement at high doses. Finally, exposure to both EGCG and caffeine had no effect on risk-taking, suggesting that low-dose caffeine is sufficient to mask the risk-aversion caused by EGCG. These data suggest EGCG as a potential therapeutic treatment for psychological disorders that induce compulsive risky decision-making.

Tea polyphenols ameliorates memory decline in aging model rats by inhibiting brain TLR4/NF-κB inflammatory signaling pathway caused by intestinal flora dysbiosis

AIMS

Tea is a rich source of pharmacologically active molecules that has been suggested to provide a variety of health benefits. However, its mechanism of action in aging-related intestinal flora dysbiosis mediated neuroinflammation is still unclear. This study aimed to explore whether tea polyphenols (TP) can improve memory by regulating intestinal flora mediated neuroinflammation in aging model rats.

METHODS

Ovariectomy (OVX) combined with D-galactose injection was used to establish aging rats related to menopause. The rats were divided into Sham control group, Aging model group, TP 75 mg/kg, 150 mg/kg, 300 mg/kg groups and VE group. After 12 weeks of intervention, the shuttle box test and Y maze test were used to check the memory of rats. The composition of intestinal flora was assessed by 16S rRNA sequencing technology. HE staining and ELISA were used to detect intestinal epithelial morphology and permeability, respectively. TLR4/NF-κB inflammation pathway related indicators were investigated by western blot, and the microglia activation in rat hippocampal tissue was checked by immunofluorescence.

RESULTS

In the shuttle box test and the Y maze test, compared with the Sham control group, the memory of Aging model rats was significantly declined. It was observed that the intestinal flora of Aging model rats was dysbiosis, the permeability of the intestinal epithelium was increased. Further experimental results showed that the expression of TLR4/NF-κB inflammatory pathway related proteins in the hippocampus were increased, and the excessive activation of microglia was observed. The beneficial effects of TP intervention have been found to prevent memory decline and significantly improve brain inflammation induced by intestinal flora dysbiosis, and TP 300 mg/kg showed a more obvious advantage than TP 75 mg/kg. TP 300 mg/kg can significantly improve the behavior of rats, improve the composition and diversity of the intestinal flora, and the shape and function of the intestinal epithelium. By reversing the increased expression levels of TLR4, IRAK, p-IκBα and nuclear NF-κB p65 proteins in the hippocampus of Aging model rats, the activation of microglia in the CA1, CA3 and Dentate gyrus (DG) sub-regions of the hippocampus can be inhibited.

CONCLUSION

TP inhibits the brain TLR4/NF-κB inflammatory signal pathway caused by the dysbiosis of intestinal flora, which may be one of the mechanisms to improve the memory decline in aging model rats.

Epigallocatechin-3-Gallate-Loaded Liposomes Favor Anti-Inflammation of Microglia Cells and Promote Neuroprotection

Microglia-mediated neuroinflammation is recognized to mainly contribute to the progression of neurodegenerative diseases. Epigallocatechin-3-gallate (EGCG), known as a natural antioxidant in green tea, can inhibit microglia-mediated inflammation and protect neurons but has disadvantages such as high instability and low bioavailability. We developed an EGCG liposomal formulation to improve its bioavailability and evaluated the neuroprotective activity in in vitro and in vivo neuroinflammation models. EGCG-loaded liposomes have been prepared from phosphatidylcholine (PC) or phosphatidylserine (PS) coated with or without vitamin E (VE) by hydration and membrane extrusion method. The anti-inflammatory effect has been evaluated against lipopolysaccharide (LPS)-induced BV-2 microglial cells activation and the inflammation in the substantia nigra of Sprague Dawley rats. In the cellular inflammation model, murine BV-2 microglial cells changed their morphology from normal spheroid to activated spindle shape after 24 h of induction of LPS. In the in vitro free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, EGCG scavenged 80% of DPPH within 3 min. EGCG-loaded liposomes could be phagocytized by BV-2 cells after 1 h of cell culture from cell uptake experiments. EGCG-loaded liposomes improved the production of BV-2 microglia-derived nitric oxide and TNF-α following LPS. In the in vivo Parkinsonian syndrome rat model, simultaneous intra-nigral injection of EGCG-loaded liposomes attenuated LPS-induced pro-inflammatory cytokines and restored motor impairment. We demonstrated that EGCG-loaded liposomes exert a neuroprotective effect by modulating microglia activation. EGCG extracted from green tea and loaded liposomes could be a valuable candidate for disease-modifying therapy for Parkinson’s disease (PD).

Beneficial Effects of Epigallocatechin-3-O-Gallate, Chlorogenic Acid, Resveratrol, and Curcumin on Neurodegenerative Diseases

Many observational and clinical studies have shown that consumption of diets rich in plant polyphenols have beneficial effects on various diseases such as cancer, obesity, diabetes, cardiovascular diseases, and neurodegenerative diseases (NDDs). Animal and cellular studies have indicated that these polyphenolic compounds contribute to such effects. The representative polyphenols are epigallocatechin-3-O-gallate in tea, chlorogenic acids in coffee, resveratrol in wine, and curcumin in curry. The results of human studies have suggested the beneficial effects of consumption of these foods on NDDs including Alzheimer's and Parkinson's diseases, and cellular animal experiments have provided molecular basis to indicate contribution of these representative polyphenols to these effects. This article provides updated information on the effects of these foods and their polyphenols on NDDs with discussions on mechanistic aspects of their actions mainly based on the findings derived from basic experiments.

Health Benefits and Chemical Composition of Matcha Green Tea: A Review

Japanese matcha is a type of powdered green tea, grown in a traditional way. Shading of the plants during the growth period enhances the processes of synthesis and accumulation of biologically active compounds, including theanine, caffeine, chlorophyll and various types of catechins. Green tea contains four main catechins, i.e., (-)-epicatechin (EC), (-)-epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG), of which the latter is the most active and abundant and matcha is their best condensed source. Due to its unique chemical composition and prized flavour, which sets it apart from other tea beverages, it is considered the highest quality tea. Its health-promoting properties are attributed to the high content of antioxidant and anti-inflammatory substances. Studies confirming the high antioxidant potential of tea beverages claim that it originates from the considerable content of catechins, a type of phenolic compound with beneficial effects on human health. Due to its potential for preventing many diseases and supporting cognitive function, regular consumption of matcha may have a positive effect on both physical and mental health. The aim of this review was to compile the health benefits of matcha tea. It is the first such review to be undertaken, and presents its main bioactive compounds in a systematic manner.

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

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

ReN VM spheroids in matrix: A neural progenitor three-dimensional in vitro model reveals DYRK1A inhibitors as potential regulators of radio-sensitivity

INTRODUCTION

Pre-clinical testing of small molecules for therapeutic development across many pathologies relies on the use of in-vitro and in-vivo models. When designed and implemented well, these models serve to predict the clinical outcome as well as the toxicity of the evaluated therapies. The two-dimensional (2D) reductionist approach where cells are incubated in a mono-layer on hard plastic microtiter plates is relatively inexpensive but not physiologically relevant. In contrast, well developed and applied three dimensional (3D) in vitro models could be employed to bridge the gap between 2D in vitro primary screening and expensive in vivo rodent models by incorporating key features of the tissue microenvironment to explore differentiation, cortical development, cancers and various neuronal dysfunctions. These features include an extracellular matrix, co-culture, tension and perfusion and could replace several hundred rodents in the drug screening validation cascade.

METHODS

Human neural progenitor cells from middle brain (ReN VM, Merck Millipore, UK) were expanded as instructed by the supplier (Merck Millipore, UK), and then seeded in 96-well low-attachment plates (Corning, UK) to form multicellular spheroids followed by adding a Matrigel layer to mimic extracellular matrix around neural stem cell niche. ReN VM cells were then differentiated via EGF and bFGF deprivation for 7 days and were imaged at day 7. Radiotherapy was mimicked via gamma-radiation at 2Gy in the absence and presence of selected DYRK1A inhibitors Harmine, INDY and Leucettine 41 (L41). Cell viability was measured by AlamarBlue assay. Immunofluorescence staining was used to assess cell pluripotency marker SOX2 and differentiation marker GFAP.

RESULTS

After 7 days of differentiation, neuron early differentiation marker (GFAP, red) started to be expressed among the cells expressing neural stem cell marker SOX2 (green). Radiation treatment caused significant morphology change including the reduced viability of the spheroids. These spheroids also revealed sensitizing potential of DYRK1A inhibitors tested in this study, including Harmine, INDY and L41.

DISCUSSION & CONCLUSIONS

Combined with the benefit of greatly reducing the issues associated with in vivo rodent models, including reducing numbers of animals used in a drug screening cascade, cost, ethics, and potential animal welfare burden, we feel the well-developed and applied 3D neural spheroid model presented in this study will provide a crucial tool to evaluate combinatorial therapies, optimal drug concentrations and treatment dosages.

Potential Role of Natural Polyphenols against Protein Aggregation Toxicity: In Vitro, In Vivo, and Clinical Studies

One of the main features of neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease is the amyloidogenic behavior of disease-specific proteins including amyloid β, tau, α-synuclein, and mutant Huntingtin which participate in the formation, accumulation, and deposition of toxic misfolded aggregates. Consequently, these proteins not only associated with the progress of their respective neurodegenerative pathologies but also qualify as disease-specific biomarkers. The aim of using natural polyphenols is to target amyloid-dependent proteopathies by decreasing free radical damage and inhibiting and dissolving amyloid fibrils. We explore the effectiveness of the polyphenols epigallocatechin-3-gallate, oleuropein aglycone, and quercetin on their ability to inhibit aggregation of amyloid β, tau, and α-synuclein and mitigate other pathological features for Alzheimer's disease and Parkinson's disease. The analysis was carried from in vitro and cell line studies to animal models and clinical trials. This Review describes the use of phytochemical compounds as prophylactic agents for Alzheimer's disease, Parkinson's disease, and other proteopathies.

Neuroprotective Properties of Green Tea (Camellia sinensis) in Parkinson's Disease: A Review

Neurodegenerative disease is a collective term given for the clinical condition, which results in progressive degeneration of neurons and the loss of functions associated with the affected brain region. Apart from the increase in age, neurodegenerative diseases are also partly affected by diet and lifestyle practices. Parkinson's disease (PD) is a slow onset neurodegenerative disorder and the second most common neurodegenerative disease, which affects the motor system. Although there is no prescribed treatment method to prevent and cure PD, clinical procedures help manage the disease symptoms. Green tea polyphenols are known for several health benefits, including antioxidant, anti-inflammatory, and neuroprotective activity. The current manuscript summarizes the possible mechanisms of neuroprotective potential of green tea with a special focus on PD. Studies have suggested that the consumption of green tea protects against free-radicals, inflammation, and neuro-damages. Several in vivo studies aid in understanding the overall mechanism of green tea. However, the same dose may not be sufficient in humans to elicit similar effects due to complex physiological, social, and cultural development. Future research focused on more clinical trials could identify an optimum dose that could impart maximum health benefits to impart neuroprotection in PD.

Increased BBB permeability contributes to EGCG-caused cognitive function improvement in natural aging rats: pharmacokinetic and distribution analyses

Previous studies report that (-)-epigallocatechin-3-gallate (EGCG), the most abundant polyphenolic ingredient in green tea, has high efficacy against Alzheimer's disease (AD) in various in vivo and in vitro models. However, as a water-soluble component, how EGCG exerts its anti-AD effects in the brain was not elucidated. In the present study, we investigated the anti-AD mechanisms of EGCG in natural aging rats with cognitive impairments (CIs) assessed using Morris water maze. The rats were treated with EGCG (100 mg/kg per day, intragastrically) for 4 weeks. The expression of β-amyloid (Aβ_1-42) in the brain was detected with immunohistochemical staining. We showed that EGCG administration significantly ameliorated the CI in the aging rats with CI and decreased Aβ_1-42 plaque formation in their brains. Then we used an efficient ultra-performance liquid chromatography-tandem mass spectrometer method to evaluate EGCG concentrations in rat plasma and tissue distribution. We found that EGCG absorption was significantly increased in the aging with CI group compared with control young rats. After oral administration of EGCG (100 mg), EGCG could not be detected in the brain tissues of control young rats, but it was found in the brain tissue of aging rats with CI. By using Evans Blue assay, transmission electron microscopy, and Western blotting assay, we demonstrated that the permeability of blood-brain barrier (BBB) was significantly increased in aging rats with CI. These results suggest that the permeability change of BBB is the physiological structural basis for EGCG treatment to improve learning and memory, thus providing a solid evidence for EGCG druggability in anti-AD therapeutic field.

Epigallocatechin-3-gallate (EGCG) exert therapeutic effect on acute inflammatory otitis media in rats

INTRODUCTION

That EGCG has strong antioxidant and anti-inflammatory activities as well as antibacterial activity against many streptococcus species suggests that it may be beneficial in the treatment of AOM.

OBJECTIVE

Aim of the study is to reveal the molecular and biochemical effects of EGCG on LPS induced otitis media in rats.

METHODS

Forty-two male albino Wistar rats were randomly divided into 7 groups. Inflammation was induced by administrating 50 μL of 1 mg/ml lipopolysaccharide (LPS). EGCG used 50 and 100 mg/kg/day and combined penicillin G (PENG) 48 h after LPS injection.

RESULTS

The combined EGCG 50 and PENG group and the group with EGCG 50 alone showed the best anti-inflammatory effect on LPS-induced AOM. TNF-α and IL-1β gene expression significantly down regulated EGCG 50 and combined with PENG compared to the otitis media group. The combination of PenG and EGCG 50 led to the best histopathological improvement. Both the inflammation and the membrane thickness of this group were at almost the same level as the healthy group and tympanum was seen normal.

CONCLUSION

The results of this study make it clear that EGCG plays an important role in antioxidant and anti-inflammatory activity during AOM.

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.

Pathophysiological mechanisms of diabetic cardiomyopathy and the therapeutic potential of epigallocatechin-3-gallate

Cardiovascular complications are considered one of the leading causes of morbidity and mortality among diabetic patients. Diabetic cardiomyopathy (DCM) is a type of cardiovascular damage presents in diabetic patients independent of the coexistence of ischemic heart disease or hypertension. It is characterized by impaired diastolic relaxation time, myocardial dilatation and hypertrophy and reduced systolic and diastolic functions of the left ventricle. Molecular mechanisms underlying these pathological changes in the diabetic heart are most likely multifactorial and include, but not limited to, oxidative/nitrosative stress, increased advanced glycation end products, mitochondrial dysfunction, inflammation and cell death. The aim of this review is to address the major molecular mechanisms implicated in the pathogenesis of DCM. In addition, this review provides studies conducted to determine the pharmacological effects of (-)-epigallocatechin-3-gallate (EGCG), the major polyphenol in green tea, focusing on its therapeutic potential against the processes involved in the pathogenesis and progression of DCM. EGCG has been shown to exert several potential therapeutic properties both in vitro and in vivo. Given its therapeutic potential, EGCG might be a promising drug candidate to decrease the morbidity and mortality associated with DCM and other diabetes complications.

Beneficial Effects of Green Tea Catechins on Neurodegenerative Diseases

Tea is one of the most consumed beverages in the world. Green tea, black tea, and oolong tea are made from the same plant Camellia sinensis (L.) O. Kuntze. Among them, green tea has been the most extensively studied for beneficial effects on diseases including cancer, obesity, diabetes, and inflammatory and neurodegenerative diseases. Several human observational and intervention studies have found beneficial effects of tea consumption on neurodegenerative impairment, such as cognitive dysfunction and memory loss. These studies supported the basis of tea's preventive effects of Parkinson's disease, but few studies have revealed such effects on Alzheimer's disease. In contrast, several human studies have not reported these favorable effects with regard to tea. This discrepancy may be due to incomplete adjustment of confounding factors, including the method of quantifying consumption, beverage temperature, cigarette smoking, alcohol consumption, and differences in genetic and environmental factors, such as race, sex, age, and lifestyle. Thus, more rigorous human studies are required to understand the neuroprotective effect of tea. A number of laboratory experiments demonstrated the benefits of green tea and green tea catechins (GTCs), such as epigallocatechin gallate (EGCG), and proposed action mechanisms. The targets of GTCs include the abnormal accumulation of fibrous proteins, such as Aβ and α-synuclein, inflammation, elevated expression of pro-apoptotic proteins, and oxidative stress, which are associated with neuronal cell dysfunction and death in the cerebral cortex. Computational molecular docking analysis revealed how EGCG can prevent the accumulation of fibrous proteins. These findings suggest that GTCs have the potential to be used in the prevention and treatment of neurodegenerative diseases and could be useful for the development of new drugs.

Epigallocatechin-3-gallate confers protection against corticosterone-induced neuron injuries via restoring extracellular signal-regulated kinase 1/2 and phosphatidylinositol-3 kinase/protein kinase B signaling pathways

Extensive studies suggested epigallocatechin-3-gallate (EGCG) has significant neuroprotection against multiple central neural injuries, but the underlying mechanisms still remain poorly elucidated. Here we provide evidence to support the possible involvement of extracellular signal-regulated kinase 1/2 (ERK1/2) and phosphatidylinositol-3 kinase/ protein kinase B (PI3K/AKT) pathways in EGCG-mediated protection against corticosterone-induced neuron injuries. As an essential stress hormone, corticosterone could induce obvious neurotoxicity in primary hippocampal neurons. Pre-treatment with EGCG ameliorated the corticosterone-induced neuronal injuries; however, it was blocked by pharmacological inhibitors for ERK1/2 (U0126) and PI3K/AKT (LY294002). Furthermore, the results confirmed that EGCG restored the corticosterone-induced decrease of ERK1/2 and PI3K/AKT phosphorylation, and attenuated the corticosterone-induced reduction of peroxisome proliferators-activated receptor-γ coactivator-1α (PGC-1α) expression and ATP production. Taken together, these findings indicated that EGCG has significant neuroprotection against corticosterone-induced neuron injuries partly via restoring the ERK1/2 and PI3K/AKT signaling pathways as well as the PGC-1α-mediated ATP production.

In vitro screening of dual flavonoid combinations for reversing P-glycoprotein-mediated multidrug resistance: Focus on antiepileptic drugs

The combined use of different P-glycoprotein (P-gp) inhibitors may be a relevant approach to the synergistic and safer inhibition of the P-gp-mediated drug efflux. Herein, we aimed to explore dual combinations of the flavonoids baicalein, (-)-epigallocatechin gallate, kaempferol, quercetin and silymarin to reverse the interference of P-gp on the intracellular accumulation of antiepileptic drugs (AEDs). The intracellular accumulation of rhodamine 123 (a classic P-gp substrate) and of several commonly used AEDs (carbamazepine, phenytoin, oxcarbazepine) or their metabolites (carbamazepine-10,11-epoxide and licarbazepine) was evaluated in MDCK-MDR1 cells in the presence and absence of individual flavonoids and their combinations. A selected flavonoid combination [(-)-epigallocatechin gallate/silymarin] was also evaluated in transepithelial transport experiments using licarbazepine (active metabolite of oxcarbazepine) as a model compound. Most flavonoid combinations increased rhodamine 123 intracellular uptake in a greater extent than their additive individual effects at similar concentrations. Moreover, selected (-)-epigallocatechin gallate/silymarin and kaempferol/baicalein combinations also enhanced the intracellular accumulation of all AEDs and metabolites. Overall, the combination of (-)-epigallocatechin gallate/silymarin was the most promising one. Thus, dual flavonoid combinations may be useful to overcome the P-gp-mediated efflux of AEDs and their metabolites, making their association to AED therapy a potentially valuable approach to circumvent pharmacoresistance in epilepsy.

(-)-Epigallocatechin-3-gallate enhances poly I:C-induced interferon-λ1 production and inhibits hepatitis C virus replication in hepatocytes

AIM

To investigate the effect of (-)-epigallocatechin-3-gallate (EGCG) on polyinosinic-polycytidylic acid (poly I:C)-triggered intracellular innate immunity against hepatitis C virus (HCV) in hepatocytes.

METHODS

A cell culture model of HCV infection was generated by infecting a hepatoma cell line, Huh7, with HCV JFH-1 strain (JFH-1-Huh7). Poly I:C with a high molecular weight and EGCG were used to stimulate the JFH-1-Huh7 cells. Real-time reverse transcription-polymerase chain reaction was used to detect the expression levels of intracellular mRNAs and of intracellular and extracellular HCV RNA. Enzyme-linked immunosorbent assay was used to evaluate the interferon (IFN)-λ1 protein level in the cell culture supernatant. Immunostaining was used to examine HCV core protein expression in Huh7 cells.

RESULTS

Our recent study showed that HCV replication could impair poly I:C-triggered intracellular innate immune responses in hepatocytes. In the current study, we showed that EGCG treatment significantly increased the poly I:C-induced expression of Toll-like receptor 3 (TLR3), retinoic acid-inducible gene I, and IFN-λ1 in JFH-1-Huh7 cells. In addition, supplementation with EGCG increased the poly I:C-mediated antiviral activity in JFH-1-Huh7 cells at the intracellular and extracellular HCV RNA and protein levels. Further investigation of the mechanisms showed that EGCG treatment significantly enhanced the poly I:C-induced expression of IFN-regulatory factor 9 and several antiviral IFN-stimulated genes, including ISG15, ISG56, myxovirus resistance A, and 2'-5'-oligoadenylate synthetase 1, which encode the key antiviral elements in the IFN signaling pathway.

CONCLUSION

Our observations provide experimental evidence that EGCG has the ability to enhance poly I:C-induced intracellular antiviral innate immunity against HCV replication in hepatocytes.

Breast cancer chemopreventive and chemotherapeutic effects of Camellia Sinensis (green tea): an updated review

Introduction

Camellia sinensis belongs to the plant family of Theaceae, native to East Asia, the Indian Subcontinent and Southeast Asia, but naturalized in many parts of the world. The aim of this study was to overview its anti-breast cancer chemopreventive and chemotherapeutic effects. This review article is aimed to overview breast cancer chemopreventive and chemotherapeutic effects of Camellia sinensis (green tea).

Methods

This review article was carried out by searching studies in PubMed, Medline, Web of Science, and IranMedex databases. The initial search strategy identified around 108 references. In this study, 68 studies were accepted for further screening, and met all our inclusion criteria [in English, full text, chemopreventive and chemotherapeutic effects of Camellia sinensis and dated mainly from the year 1999 to 2016. The search terms were Camellia sinensis, chemopreventive, chemotherapeutic properties, pharmacological effects.

Result

The result of this study suggested that the catechin available in Camellia sinensis has properties which can prevent and treat breast cancer. It has also been shown to inhibit proliferation of breast cancer cells and to block carcinogenesis. It was found that increased Camellia sinensis consumption may lower the risk of breast cancer. Camellia sinensis intake was shown to reduce the risk of breast cancer incidence. In addition, potential breast cancer chemopreventive effect of Camellia sinensis both in vivo and in vitro was highly confirmed. However, the evidence of low effect and no effect was observed. More clinical trial studies are needed to prove its anti-breast cancer activity decisively.

Conclusion

Camellia sinensis is broadly utilized as a part of customary medication since antiquated time because of its cost adequacy, and fewer reaction properties. The studies demonstrated anti-breast cancer activity of Camellia sinensis and its component by adjusting cell signaling pathways such as angiogenesis, apoptosis, and transcription factor. Furthermore, Camellia sinensis and its chemical compound was shown to be extremely useful in the development of novel anticancer medications.