Epigallocatechin-3-gallate exerts antihypertensive effects and improves endothelial function in spontaneously hypertensive rats

Objective:To investigate the effect of epigallocatechin-3-gallate(EGCG)on endothelial dysfunction in spontaneously hypertensive rats(SHR).Methods:Wistar-Kyoto(WKY)rats and SHR were divided into four groups;WKY control,SHR control and SHR treated with EGCG(50 mg/kg/day)or losartan(10 mg/kg/day).The treatment was given daily for 4 weeks by oral gavage and the blood pressure was monitored by tail-cuff method every 3 days.Acetylcholineinduced endothelium-dependent relaxations were assessed in isolated phenylephrine-precontracted aortic rings at the end of treatment.The vascular levels of reactive oxygen species,nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate were also measured.Moreover,the expression of angiotensinⅡtype 1(AT_(1))receptor protein was determined.Results:The systolic blood pressure was significantly decreased in SHR treated with EGCG.The impaired endothelium-dependent relaxation was significantly improved in aortic ring isolated from the EGCG-treated SHR group.EGCG also significantly increased the levels of nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate,while decreasing the level of reactive oxygen species and the protein expression of AT_(1)receptor in SHR.Conclusions:EGCG attenuates endothelial dysfunction in SHR by decreasing oxidative stress and increasing vascular nitric oxide bioavailability,which may be modulated partly by inhibition of vascular AT_(1)receptors.An increase in endothelium-dependent relaxation may contribute to a decrease in blood pressure in hypertensive animals.

Epigallocatechin-3-gallate Alleviates Cognitive Deficits in APP/PS1 Mice

Alzheimer's disease(AD)shows cognitive impairments in clinic,which is multifactorial with different etiopathogenic mechanisms such as A|3 deposition,neuroinflammation and neuronal dystrophy involved.Therefore,multi-targets drugs with neuroprotective,anti-amyloidogenic and anti-inflammatory properties will be effective in AD treatment.Epigallocatechin-3-gallate(EGCG)possesses a broad spectrum of pharmacological activities in the prevention and treatment of multiple neurodegenerative diseases.In the present study,we showed that oral administration of EGCG(50 mg/kg)for 4 months significantly attenuated the cognitive deficits in APP/PS1 transgenic mice,which served as AD model.Moreover,EGCG induced an improvement in dendritic integrity and expression levels of synaptic proteins in the brain of APP/PS 1 mice.And EGCG exerted obvious anti-inflammatory effects,which was manifested by alleviating microglia activation,decreasing pro-inflammatory cytokine(IL-β)and increasing anti-inflammatory cytokines(IL-10,IL-β).Furthermore,p-amyloid(AP)plaques were markedly reduced in the hippocampus of 6-month old APP/PS 1 mice after EGCG treatment.In conclusion,these findings indicate that EGCG improves AD-like cognitive impairments through neuroprotective,anti-amyloidogenic and anti-inflammatory effects,thus is a promising therapeutic can didate for AD.

Neuroprotective effect of epigallocatechin-3-gallate on hemisection-induced spinal cord injury in rats

Epigallocatechin-3-gallate （EGCG）, a naturally occurring compound in green tea, has been widely used as an antioxidant agent. In the present study, model rats with acute spinal cord injury were intraperitoneally injected with 25, 50, and 100 mg/kg EGCG, and spinal cord ultrastructure, oxidative stress reaction, inflammatory factors, and apoptosis-associated gene expression were observed. Results showed that EGCG attenuated neuronal and axonal injury 24 hours post injury. It also decreased serum intedeukin-113, tumor necrosis factor-a, and intercellular adhesion molecule-1 release, and decreased apoptosis-associated gene expression. Furthermore, it increased the level of the superoxide anion （O2-）, superoxide dismutase, and B-cell lymphoma/leukemia-2, and reduced malondialdehyde levels. Furthermore, it reduced the expression of the pro-apoptotic protein Bax. Noticeably, EGCG at the 100 mg/kg dosage exhibited similar effects as methylprednisolone sodium succinate, which has been frequently used for clinical acute spinal cord injury. The results demonstrated that EGCG can significantly inhibit inflammation, suppress oxidation, and reduce apoptosis in acute spinal cord injury.

Epigallocatechin-3-gallate treatment to promote neuroprotection and functional recovery after nervous system injury

Traumatic spinal cord injury （SCI） causes motor paralysis, sensory anesthesia and autonomic dysfunction below the le- sion site and additionally some SCI patients refer neuropathic pain together with these signs and symptoms. Clinical and experimental studies have revealed the main pathological changes of injured spinal cord implicated in all these signs and symptoms, including neuropathic pain. After few hours of traumatic SCI, it is usual to observe broken blood brain barrier with plasma and blood cells extravasation, cell necrosis, disruption of ascending and descending spinal cord pathways and increased potassium and glutamate. Glutamate contributes to excitotoxicity of neurons whereas potassium facilitates ectopic depolarization of survival neurons and activation of resident microglia.

Protective Effects of Epigallocatechin-3-gallate on Intestinal Ischemia Reperfusion Injury through Enhanced Activation of PI3K/Akt Pathway in Rats

Inflammation plays a critical role in intestinal ischemia reperfusion injury（IRI）. Epigallocatechin-3-gallate（EGCG） has been demonstrated to possess anti-inflammatory effect. This study examined the effect of EGCG on intestinal IRI and explored the possible mechanisms. Male Wistar rats were randomly divided into three groups： sham-operated group（Sham）, IRI control group（IRI） and IRI-EGCG group（EGCG）. Rats in IRI-EGCG group were administered dissolved EGCG in drinking water（0.4 mg/m L） for 14 days prior to IRI induction. A rat model of intestinal IRI was established by ligating the superior mesenteric artery（SMA） for 30 min, followed by reperfusion for 1 h. Intestinal histology, pro-inflammatory cytokines and mediators were examined and the effect of EGCG on PI3K/Akt signalling was assessed. EGCG significantly alleviated the pathological changes of the intestine and suppressed the IRI-induced up-regulation of TNF-α, IL-1 and IL-6 m RNA and protein expression in the serum and intestine. The mechanism might be that EGCG enhanced the activation of PI3K/Akt signalling pathway. In conclusion, the administration of EGCG can significantly mitigate the acute intestinal IRI in rats by enhancing the activation of PI3K/Akt signalling pathway to suppress inflammatory response and might be a promising alternative for the prevention or treatment of intestinal IRI in the clinical practice.

Epigallocatechin-3-gallate attenuates lipopolysaccharideinduced inflammation in human retinal endothelial cells

AIM:To investigate the mechanism underlying the anti-inflammatory effects of epigallocatechin-3-gallate(EGCG)in lipopolysaccharide(LPS)-stimulated human retinal endothelial cells(HRECs).METHODS:HRECspre-treatedwithEGCG(0-100μmol/L)were stimulated with LPS(250 ng/mL).Levels of tumor necrosis factor alpha(TNF-α),vascular endothelial growth factor(VEGF),monocyte chemotactic protein-1(MCP-1)and nitric oxide(NO)in the supernatants were determined by enzyme-linked immunosorbent assay(ELISA)and Griess assay.The protein expression of phosphorylated extracellular signal-regulated kinase(ERK)1/2 and p38 mitogen-activated protein kinases(p38)were determined by Western blot analysis.RESULTS:EGCG pre-treatment significantly inhibited the secretion of TNF-α,VEGF,MCP-1 and NO in LPSstimulated HRECs.Moreover,EGCG effectively attenuated LPS-induced activation and phosphorylation of ERK1/2 and p38 in HRECs in a dose-dependent manner.CONCLUSION:EGCG exhibited inhibitory effects on LPS-induced pro-inflammatory cytokines production by modulating ERK1/2 and p38 pathways in HRECs,suggesting EGCG as a potential candidate for antiinflammatory intervention.

Epigallocatechin-3-gallate suppresses transforming growth factor-beta signaling by interacting with the transforming growth factor-beta typeⅡreceptor

AIM: To investigate the(-)-epigallocatechin-3-gallate(EGCG) binding to transforming growth factor-β(TGF-β) type Ⅱ receptor(TGFRⅡ).METHODS: The expression of α-smooth muscle actin(α-SMA) was used as a marker for fibrotic change inhuman lung fibroblast MRC-5 cells. The α-SMA expression level was determined by western blotting and immunohistological analysis. We examined whether the anti-fibrotic effects of EGCG on MRC-5 cells was dependent on antioxidant mechanism by using edaravone and N-acetylcysteine(NAC). The suppression effects of EGCG on Smad2/3 activation were studied by confocal fluorescence microscopy. The binding of EGCG to recombinant TGFRⅡ protein was analyzed by immunoprecipitation and affinity chromatography.RESULTS: When MRC-5 cells were treated with TGF-β, EGCG decreased the expression of α-SMA in a dose dependent manner, whereas catechin did not influence the α-SMA expression in the cells. Except for EGCG, antioxidant compounds(e.g., edaravone and NAC) had no effects on the TGF-β-induced α-SMA expression. Nuclear localization of phosphorylated Smad2/3 was observed after TGF-β treatment; however, EGCG treatment attenuated the nuclear transportation of Smad2/3 in the presence or absence of TGF-β. After a TGFRⅡ expression vector was introduced into COS-7 cells, cell lysates were untreated or treated with EGCG or catechin. The immunoprecipitation experiments using the lysates showed that EGCG dose-dependently bound to TGFRⅡ and that catechin did not at all. Affinity chromatography study indicated that EGCG would bind to TGFRⅡ.CONCLUSION: Our results demonstrate that EGCG interacts with TGFRⅡ and inhibits the expression of α-SMA via the TGF-β-Smad2/3 pathway in human lung fibroblast MRC-5 cells.

Inhibition of Invasion and Up-regulation of E-cadherin Expression in Human Malignant Melanoma Cell Line A375 by(-)-Epigallocatechin-3-gallate

The inhibitory effects of （-）-epigallocatechin-3-gallate （EGCG） on the invasion of human malignant melanoma cell line A375 and the possible molecular mechanisms of this effect were investiaged. A375 cells were pretreated with 20 μg/mL EGCG for 24, 48 and 72 h respectively and the E-cadherin expression was detected by Western blot analysis. A375 cells were also pretreated with different concentrations of EGCG （1, 5, 10 and 20 μg/mL） for 72 h and the expression of E-cadherin was measured by RT-PCR. The adhesion and invasion of A375 cells were tested by cell-matrigel adhesion assay and matrigel invasion assay respectively. The results showed that EGCG could significantly up-regulate the expression of E-cadherin time-and concentration-dependently （both P〈0.05）. Statistical analysis showed that A375 cells invasion was inhibited by EGCG and correlated with the up-regulation of E-cadherin expression. It was suggested that EGCG strongly inhibited invasion of A375 cells, and the inhibition mechanism was possibly associated with the up-regulation of E-cadherin expression.

(-)-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 m RNAs 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 IFNstimulated 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.

Preparation of chitosan-Epigallocatechin-3-O-gallate nanoparticles and their inhibitory effect on the growth of breast cancer cells

In this paper,we prepared the nanoparticle drug carrier system between nanoparticles chitosan and Epigallocatechin-3 O-gallate(EGCG)for breast cancer cell inhibiting application.For this drug carrier system,chitosan acts as a carrier and EGOG as a drug.Which were systematically characterized and thoroughly evaluated in terms of their inhibition rate and biocompatibility.We also did a cell scratch test and the result indicated that the chitosan EGCG nanoparticles have inhibitory effect on the growth of breast cancer cells.The inhibition rate could reach up to 21.91%.This work revealed that the modification of nanopartidles paved a way for specific biomedical applications.

Protective effects of (-)-epigallocatechin-3-gallate on D-galactose-induced neuronal apoptosis in mice

BACKGROUND： The neuroprotective effects of （-）-epigallocatechin-3-gallate （EGCG）, the main polyphenolic constituent of green tea, have been widely reported. However, the action mechanisms, in particular in D-galactose-induced aging mice, remain poorly understood. OBJECTIVE： The present study investigated the protective effects of EGCG on D-galactose-induced hippocampus neuronal apoptosis in aging mice, as well as the relationship with expression of p751CD, JNK2, and p53 proteins. DESIGN, TIME AND SETTING： A randomized, controlled, molecular biological, animal experiment was performed at the Laboratory of Pharmacology, Pharmaceutical College of China Medical University, China, from September 2006 to July 2008. MATERIALS： D-galactose and EGCG （Sigma, USA）, as well as terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling （TUNEL） In Situ Cell Apoptosis Detection Kit （Promega, USA）, were used in this study. METHODS： A total of 64 mice were equally and randomly divided into D-galactose model, low-dose EGCG, high-dose EGCG, and control groups. Mice in the D-galactose model, low-dose EGCG, and high-dose EGCG groups were subcutaneously injected with 3% D-galactose （150 mg/kg）, daily for 6 weeks, to establish a mouse model of aging. Mice in the control group were treated with saline （5 mL/kg）. At 3 weeks following injection, mice in the low-dose EGCG and high-dose EGCG groups were orally administered EGCG at a dose of 2 mg/kg and 6 mg/kg, respectively, once a day, for 4 consecutive days. Mice in the control and D-galactose model groups received distilled water （5 mL/kg）. MAIN OUTCOME MEASURES： Memory function was evaluated using a step-through passive avoidance test. Neuronal apoptosis in the mouse hippocampus was detected using TUNEL staining. Expression levels of the intracellular domain of the p75 neurotrophin receptor （p75NTR）-p751CD, JNK2, and p53 proteins in the hippocampus were determined using Western blot analysis. RESULTS： The aging mouse model was induced by subcutaneous injection of D-galactose, which resulted in obvious memory impairment, increased apoptotic index, and increased protein expression levels of p751CD, JNK2, and p53 in the hippocampus, compared with control mice （P 〈 0.01）. Oral EGCG administration （2 or 6 mg/kg） for 4 weeks significantly improved levels of memory deficit in the aging mice and reduced apoptotic indices and protein expression levels of p751CD, JNK2, and p53 in the mouse hippocampus （P 〈 0.01）. CONCLUSION： Results from this study demonstrated increased protein expression levels of p751CD, JNK2, and p53, as well as increased hippocampal neuronal apoptosis in a D-galactose-induced mouse model of aging. EGCG provided protective effects against D-galactose-induced neuronal apoptosis in the hippocampus by reducing protein expression levels of p751CD, JNK2, and p53 proteins in the hippocampus of aging mice.

Integrating network pharmacology and pharmacological evaluation for deciphering the mechanism of(-)-epigallocatechin-3-gallate alleviating ethanol-induced endothelial cells injury

Objective To investigate the potential therapeutic targets and pharmacological mechanism of(-)-epigallocatechin-3-gallate(EGCG)based on network pharmacology and experimental verification.METHODS The druggability of EGCG was measured by the traditional Chinese medicine systems pharmacology(TCMSP)server,and potential targets of EGCG were identified by Pharm Mapper and Drug Repositioning and Adverse drug Reaction via Chemical-Protein Interactome(DRAR-CPI).The potential targets were imported into GeneMANIA database to obtain the protein-protein direct interaction network,and target physical interaction,co-expression,prediction,genetic interaction,and shared protein domains.The biological process,molecular functions,cellular components and KEGG signaling pathways of potential targets were analyzed using DAVID database.For further study,ethanol was used to establish a model of endothelial injury in vitro.The cell viability was assayed by MTT method,the cellular apoptosis was stained by Annexin V/PI,and the expression levels of Bcl-2,Bax and cleved-caspase-3 were tested by Western blotting.Then,JC-1 and nuclear translocation of NF-κB experiments were used to study the mitochondrial membrane potential and nuclear translocation.RESULTS The oral availability of EGCG was 55.09%(≥30%)and drug-like index was 0.77(≥0.18),which were considered pharmacokinetically active.17 potential targetable proteins of EGCG were predicted by Pharm Mapper and DRAR-CPI.Further research showed that 68.13%displayed similar co-expression characteristics,26.11%physical interactions,and 2.74%shared the same protein domain.The depth network analysis results showed that the biofunctions of EGCG were mainly by regulating glutathione derivative biosynthetic process,glutathione metabolic process,nitrogen compound metabolic process etc..via drug binding,catalytic activity,glutathione transferase activity,anion binding etc..in sarcoplasmic reticulum,spindle pole,microtubule cytoskeleton and cytoplasm.KEGG enrichment analysis showed that Glutathione metabolism,IL^(-1)7 signaling pathway,EGFR tyrosine kinase inhibitor resistance,PI3K-Akt signaling pathway and other pathways were involves in the biofunction of EGCG.The above analyses indicated that EGCG exerts its biofunction through antioxidant and anti-inflammatory mechanisms.The experimental results showed that ethanol 20.0 mmol·L^(-1) decreased cell viability,Bcl-2 expression,and increased cell apoptosis,the intracellular ROS,as well as the expression of Bax and cleaved-caspase-3 of human endothelial cells.However,treatment of the cells with EGCG can significantly alleviate ethanol induced endothelial cells injury.Further study showed that EGCG significantly alleviates ethanol induced mitochondrial depolarization and nuclear translocation of NF-κB.CONCLUSIONS EGCG exerts pharmacological efficacies on ethanol induced endothelial cell injury through multi-target,multi-function and multi-pathway mode.Protective effect of EGCG on ethanol induced cell injury was mainly through alteration of mitochondrial function and NF-κB translocation.Therefore,EGCG have great potential in protecting against endothelial dysfunction of the persons who are chronically abuse of ethanol.This study also provides a new understanding of EGCG in clinical application on cardiovascular and cerebrovascular diseases.

The <i>in Vivo</i>Antioxidant Effects of (&minus;)-Epigallocatechin-3-Gallate Consumption in Healthy Postmenopausal Women Measured by Urinary Excretion of Secondary Lipid Peroxidation Products

The present study was carried out to determine whether the consumption of epigallocatechin (EGCG), the major bioactive green tea catechin, exerts a positive effect on lowering in vivo lipid peroxidation, a measure of oxidative stress, in healthy postmenopausal women. Urinary excretion of secondary lipid peroxidation products, a measure of in vivo lipid peroxidation, was determined in 40 participants randomly assigned to consume a green tea catechin extract (843.0 ± 44.0 mg EGCG/d) or placebo capsules for 12 months. Urine samples were analyzed for individual polar and nonpolar lipophilic aldehydes and related carbonyl compounds by high-performance liquid chromatography (HPLC) at the beginning and at the end of the 12-month intervention period. Results show that two nonpolar aldehydes, nonanal and decatrienal, were both 48% lower (p in vivo antioxidant activity exists with long-term EGCG consumption, which could slightly limit oxidative damage associated with lipid peroxidation and the onset and progression of chronic diseases.

(-)-Epigallocatechin-3-gallate protects spiral ganglion neurons against amikacin-induced apoptosis

Morphology of spiral ganglion neurons （SGNs） in Sprague-Dawley rats before and after amikacin treatment was observed by transmission electron microscopy. Amikacin induced cochlear SGN apoptosis. Immunohistochemical staining and RT-PCR revealed a decrease in Bcl-2 protein ex-pression, and an increase in Bax protein, caspase-3 protein and caspase-6 mRNA expression fol-lowing amikacin treatment. （-）-Epigallocatechin-（3）-gallate （EGCG） inhibited SGN Bax protein, caspase-3 protein and caspase-6 mRNA expression, and enhanced Bcl-2 protein expression, thereby decreasing SGN apoptosis. Results demonstrated that EGCG can protect SGNs against amikacin-induced injury.

Health promoting activities and corresponding mechanism of(–)-epicatechin-3-gallate

(–)-Epicatechin-3-gallate(ECG),a bioactive polyphenolic compound,has contributed a lot to the health benefits of green tea.Great attention has been focused on(–)-epigallocatechin-3-gallate(EGCG),but limited research has been performed towards ECG.Like EGCG,ECG also possesses various pharmacological and physiological properties,such as mediation of antioxidant activities,anti-inflammation response,regulation of cell proliferation and apoptosis,as well as anticancer properties during angiogenesis,invasion and metastasis stages.Nontoxic ECG has various molecular targets within the cells,including CYP enzymes,phaseⅡdetoxification and antioxidant enzymes,as well as pro-inflammatory mediators.The antineoplastic mechanism contains inhibition of phase 1 CYP enzymes,induction of phaseⅡdetoxification and antioxidant enzymes,high anti-inflammatory efficacy,arrest of cell cycle progression,regulation of apoptosis,as well as mediation of metastasis processes.In particular,the gallate moiety of ECG is critical for mediating inhibitory effects towards cancer cells.Besides regulation of intracellular signaling pathways,ECG also inhibits RNase A and matrix metalloproteinase enzymatic activity via chelating metals(copper and zinc)in cancer cells.This review has summarized recent studies on pharmacological properties of ECG,and discussed corresponding mechanism on modulation of cellular signaling events by ECG,hoping to broaden its multiple usage.

Dietary Green Tea Extract and Antioxidants Improve Insulin Secretory Functions of Pancreatic β-Cells in Mild and Severe Experimental Rodent Model of Chronic Pancreatitis

Chronic pancreatitis (CP) is a progressive inflammatory disorder of the pancreas. It is predominantly idiopathic (with an unknown cause) in India and mostly due to alcohol in the West. Diabetes that occur secondary to chronic pancreatitis (T3c Diabetes) is often brittle, and is difficult to attain normoglycemia with conventional treatment requiring multiple doses of insulin. Mild and severe model of CP was induced in mice by repeated intraperitoneal injections of cerulein and L-arginine respectively with an intent to study islet dysfunction and develop therapeutic strategy in animal models of CP. Dietary intervention of epigallocatechin-3-gallate (EGCG) was tested in both the models of CP for its beneficial effects on insulin secretory functions. Pancreata collected upon euthanasia were used to study alterations in the morphology of pancreatic parenchyma and inflammation by staining with H&E and fibrotic changes by Masson’s trichrome and picrosirius staining. Insulin secretory functions of islets were evaluated to test the efficacy of the dietary intervention on β-cell functions. Intraperitoneal glucose tolerance test was performed to monitor the glucose homeostasis before and after the dietary intervention. Both the models resulted in CP with dispersed acini, inflammation and fibrosis. The loss of acini and extent of fibrosis was more in L-arginine model. 2-fold improvement in glucose-stimulated insulin secretory functions of islets was observed with 0.5% EGCG dietary intervention in cerulein model of CP and 1.6-fold in L-arginine model of CP. A further improvement in insulin secretion by 3.2-fold was observed with additional dietary supplements like N-acetyl cysteine, curcumin in combination with EGCG. Our results thus demonstrate and highlight the therapeutic potential of dietary green tea (EGCG) supplementation in reversing islet dysfunction and improving glucose homeostasis in experimental chronic pancreatitis in mice.

Green tea polyphenol epigallocatechin-3-gallate inhibits the expression of nitric oxide synthase and generation of nitric oxide induced by ultraviolet B in HaCaT cells

Background Nitic oxide （NO） has been implicated in the pathogenesis of various inflammatory diseases, including sunburn and pigmentation induced by ultraviolet irradiation. Epigallocatechin-3-gallate （EGCG） is the major effective component in green tea and can protect skin from ultraviolet-induced damage. The purpose of this study was to investigate the protective mechanisms of EGCG on inducible nitric oxide synthase （iNOS） expression and NO generation by ultraviolet B （UVB） irradiation in HaCaT cells. Methods HaCaT cells were irradiated with UVB 30 mJ/cm^2 and pretreated with EGCG at varying concentrations. The iNOS mRNA was detected by reverse transcriptase polymerase chain reaction （RT-PCR） and NO production was quantified by spectrophotometric method. The expression of NF-κB P65 was measured by immunofluorescence cytochemistry staining. Results The expression of iNOS mRNA and generation of NO in HaCaT cells were increased by UVB irradiation. EGCG down regulated the UVB-induced iNOS mRNA synthesis and NO generation in a dose dependent manner. The UVB-induced activation and translocation of NF-κB were also down regulated by EGCG treatment in HaCaT cells （P〈0.01）. Conclusions Green tea derived-EGCG can inhibit and down regulate the UVB-induced activation and translocation of NF-κB, expression of iNOS mRNA and generation of NO respectively, indicating EGCG may play a protective role from UVB-induced skin damage.

Epigallocatechin-3-gallate induces apoptosis, inhibits proliferation and decreases invasion of glioma cell

Epigallocatechin-3-gallate （EGCG）, a major polyphenol in green tea, has been considered a potential therapeutic and chemopreventive agent for cancer. Glioma is a malignant tumor with high mortality but effective therapy has not yet been developed. In this study, we found that EGCG induced apoptosis in U251 glioma cells via the laminin receptor （molecular weight 67kDa） in a time- and dose-dependent manner, decreased their invasiveness and inhibited their proliferation. The mitogen-activated protein kinase pathway was shown to be involved in glioma cell apoptosis and proliferation. Furthermore, the mRNA levels of matrix metalloproteinase （MMP）-2 and MMP-9 were reduced after EGCG treatment. These results suggest that EGCG has important therapeutic effects with low toxicity and side-effects, and could be used in cancer chemoprevention.

Epigallocatechin-3-gallate Modulates MicroRNA Expression Profiles in Human Nasopharyngeal Carcinoma CNE2 Cells

Background： Epigallocatechin-3-gallate （EGCG） has exhibited antitumor properties in several types of cancers, including nasopharyngeal carcinoma （NPC）, but the molecular mechanisms underlying this function remain incompletely understood. The aim of the present study was to characterize the global impact of EGCG on the expression of microRNAs （miRNAs） in NPC cells. Methods： Using microarray analysis, the alterations of miRNA expression profiles were investigated in EGCG-treated CNE2 cells. Furthermore, the target genes and signaling pathways regulated by EGCG-specific miRNAs were identified using target prediction program and gene ontology analysis. Results： A total of 14 miRNAs exhibited 〉2-fold expression changes in a dose-dependent manner after treatment with 20 μmol/L and 40 μmol/L EGCG. Totally 43, 49, and 52 target genes from these differentially expressed miRNAs were associated with the apoptosis, cell cycle regulation, and cell proliferation, respectively. A total of 66 signaling pathways, primarily involved in cancer development and lipid and glucose metabolism, were shown to be regulated by EGCG-specific miRNAs. Conclusion： EGCG induces considerable alterations of miRNA expression profiles in CNE2 cells, which provides mechanistic insights into cellular responses and antitumor activity mediated by EGCG.

Modulation of NRF2 and UGT1A expression by epigallocatechin-3-gallate in colon cancer cells and BALB/c mice

Background Green tea is an important source of flavonoids in human diets and epidemiological data correlate green tea consumption with a reduced cancer risk. Given its complicated properties at effective concentrations, we put epigallocatechin-3-gallate （EGCG） that previously reported on its anti-proliferative activities against several cancer cell lines on our research agenda to further examine the mechanism of its chemopreventive potential. Methods RNA interference （RNAi） expression vector pSilencer 3.1-H1 was used to construct recombinant nuclear factor erythroid 2 related factor 2 （Nrf2）-targeting RNAi plasmids. EGCG （5 μg/ml） was added into the culture fluid of cells before and after transfection. RT-PCR and Western blotting were used to detect the expression of uridine 5＇-diphosphate-glucuronosyltransferase （UGT）IA in cells. Forty male BALB/c mice were assigned to four groups： a normal unexposed control and three groups treated with varying doses of EGCG. Four weeks later, the mice were sacrificed, and their colon tissues were subjected to mRNA and protein expression of Nrf2 and UGT1A via RT-PCR and Western blotting analysis. Results EGCG up-regulated the expression of Nrf2 and increased the level of UGT1A in cells. The blockade of Nrf2 activity via RNA intervention largely attenuated the induction of UGT1A expression by EGCG. In mice, the mRNA and protein levels of Nrf2 and UGT1A detected by RT-PCR and Western blotting increased （both P 〈 0.05 compared with the control）. This increase in Nrf2 expression also had a positive correlation with an increased UGT1A expression. Conclusions EGCG mediated its effect in part by inducing the NRF2 signaling pathway and increasing UGT1A expression. Both in vitro and in vivo studies demonstrated the role of NRF2 and UGT1A expression in the potential use of EGCG as a possible chemopreventive agent and supported further study of EGCG for cancer treatment.