The epigallocatechin gallate derivative Y reverses drug resistance mediated by the ABCB1 transporter both and

Previously, we reported that Y, a new epigallocatechin gallate derivative, is efficacious in reversing doxorubicin (DOX)--mediated resistance in hepatocellular carcinoma BEL-7404/DOX cells. In this study, we evaluated the efficacy of Y in reversing drug resistance both and by determining its effect on the adenosine triphosphate-binding cassette protein B1 transporter (ABCB1 or P-glycoprotein, P-gp). Our results showed that Y significantly sensitized cells overexpressing the ABCB1 transporter to anticancer drugs that are ABCB1 substrates. Y significantly stimulated the adenosine triphosphatase activity of ABCB1. Furthermore, Y exhibited a higher docking score as compared with epigallocatechin gallate inside the transmembrane domain of ABCB1. In addition, in the nude mouse tumor xenograft model, Y (110 mg/kg, intragastric administration), in combination with doxorubicin (2 mg/kg, intraperitoneal injection), significantly inhibited the growth of BEL-7404/DOX cell xenograft tumors, compared to equivalent epigallocatechin gallate. In conclusion, Y significantly reversed ABCB1-mediated multidrug resistance and its mechanisms of action may result from its competitive inhibition of the ABCB1 drug efflux function.

Protective effects of Epigallocatechin gallate on liver ischemia reperfusion injury in rats / 中华肝胆外科杂志

Objective To investigate the protective roles of Epigallocatechin gallate (EGCG) on liver ischemia reperfusion injury (IRI) in rats.Methods 30 healthy male SD rats were selected and equally and randomly divided into 3 groups.Sham group,IRI group and IRI-EGCG group were established to construct 70％ liver IRI rat model.Drinking water with 0.4 mg/ml EGCG was administered for 2 weeks before the experiment in IRI-EGCG group.HE staining was performed to evaluate the injury.Transaminases in serum were investigated to assess liver injury.p-p85 and p-AKT was detected by Western-blot assay.qPCR was carried out to study the mRNA expression of TNF-α,IL-6 and IL-1β in liver tissue.The secretion of TNF-α,IL-6 and IL-1 β in serum was examined with ELISA assay.Results EGCG pretreatment reduced ASTand ALT in serum [AST:(550.0 ±66.5) IU/L vs.(220.0 ±63.5) IU/L;ALT:(376.0 ± 25.7) IU/L vs.(158.0 ± 33.1) IU/L,all P ＜ 0.05] and mitigated liver tissue damage.p-p85 and p-AKT increased due to liver IRI,and IRI-EGCG group showed higher expression of p85 and AKT.The proinflammatory cytokines of TNF-α,IL-6 and IL-1 β exhibited a relatively lower mRNA expression in IRI-EGCG group comparing with IRI group.IRI-EGCG group also revealed a decreased secretion of TNF-α,IL-6 and IL-1β in serum [TNF-α:(398.0±33.4) ng/Lvs.(211.0±23.6) ng/L;IL-6:(341.0±27.3) ng/L vs.(187.0±19.6) ng/L;IL-1β:(486.0±43.7) ng/L vs.(352.0±31.5) ng/L;allP＜0.05].Conclusion EGCG pretreatment can enhance IRI-induced activation of PI3K/AKT signaling and reduce the release of proinflammatory cytokines to exert liver protective effects.

Inhibitory effect of epigallocatechin gallate on the proliferation of Lewis Lung Cancer mice and A549 and Calu-3 lung cancer cells / 中国药学杂志

OBJECTIVE: To determine the inhibitory effect of EGCG on the Lewis Lung Cancer Model, to compare and preliminary to discuss the mechanism of the inhibitory effect of EGCG on the proliferation of A549 cell line and Calu-3 cell line. METHODS: Observed the inhibitory effect of EGCG on Lewis Lung Cancer in vivo. Compared the inhibitory effect of different dosages of EGCG on Calu-3 and A549 cell lines with WST-8 assay. Observed the opoptosis promotional effect of EGCG on Calu-3 cells. Compared the inhibitory effect of different dosage of EGCG on Calu-3 and A549 cell lines in PI cell number counting assay. RESULTS: EGCG inhibited the proliferation of Lewis Lung Cancer in vivo. Results of WST-8 assay showed that EGCG inhibited the proliferation of Calu-3 cell line in dose-dependent manner. However, A549 cell line showed sign of drug-resistance to EGCG. The inhibitory effect of EGCG on the proliferation of Calu-3 cell line through increasing apoptosis was observed with TUNEL assay. Cell number of Calu-3 was obviously decreased by treating of EGCG, but was not changed in A549 cell line. CONCLUSION: EGCG inhibited proliferation of Lewis Lung Cacer in vivo, and inhibited proliferation of Calu-3 cell line but didn't play the inhibitory role on A549 cell line in vitro. Copyright 2012 by the Chinese Pharmaceutical Association.

Protective Effects of Epigallocatechin Gallate in MPTP-induced Mouse Model of Parkinson's Disease / 中国康复理论与实践

@#ObjectiveTo investigate the protective effects of epigallocatechin gallate (EGCG) in a mouse model of Parkinson's disease induced by 1-Methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP).Methods32 C57BL/ 6 male mice were randomly divided into 4 groups: Model group was administrated with 16 mg/kg MPTP (i.p., four times, 2 h interval); Sham group was treated with saline; EGCG treatment group was given EGCG (5 mg/kg) after MPTP administration; normal group was just given EGCG (5 mg/kg) as treatment group. After given EGCG for 3 weeks, behavioral tests, tyrosine hydroxylase (TH) immunohistochemistry staining and the HPLC for dopamine (DA) and its metabolites were used.ResultsThe present results indicated that oral administration of EGCG significantly improved the behavioral impairement in mice induced by MPTP (P<0.05). And in the EGCG treatment group, there were more TH-positive neurons than in model group. In addition, levels of DA and its metabolites in striatum decreased significantly in MPTP group (P<0.05). Though the concentration of DA and its metabolites in EGCG treatment group tended to increase, however, there was no significance between EGCG treatment and model group.ConclusionEGCG could improve the behavioral impairment in a mouse model of Parkinson's disease induced by MPTP and protect against the loss of the dopamine neurons in the substantia nigra (SN).

(-)-Epigallocatechin Gallate Inhibits the Pacemaker Activity of Interstitial Cells of Cajal of Mouse Small Intestine

The effects of (-)-epigallocatechin gallate (EGCG) on pacemaker activities of cultured interstitial cells of Cajal (ICC) from murine small intestine were investigated using whole-cell patch-clamp technique at 30degrees C and Ca2+ image analysis. ICC generated spontaneous pacemaker currents at a holding potential of -70 mV. The treatment of ICC with EGCG resulted in a dose-dependent decrease in the frequency and amplitude of pacemaker currents. SQ-22536, an adenylate cyclase inhibitor, and ODQ, a guanylate cyclase inhibitor, did not inhibit the effects of EGCG. EGCG-induced effects on pacemaker currents were not inhibited by glibenclamide, an ATP-sensitive K+ channel blocker and TEA, a Ca2+-activated K+ channel blocker. Also, we found that EGCG inhibited the spontaneous [Ca2+]i oscillations in cultured ICC. In conclusion, EGCG inhibited the pacemaker activity of ICC and reduced [Ca2+]i oscillations by cAMP-, cGMP-, ATP-sensitive K+channel-independent manner.

Protective Effects of Epigallocatechin Gallate After UV Irradiation of Cultured Human Lens Epithelial Cells

PURPOSE: To evaluate the protective effects of epigallocatechin gallate (EGCG) against UV irradiation of cultured human lens epithelial cells. METHODS: We irradiated cultured human lens epithelial cells with a 30-second pulse from a UV lamp with an irradiance of 0.6 mW/cm2. Five minutes and 1 hour after UV irradiation, we administered 0, 5, 10, 15, 25, 50, or 100 uM EGCG. The cell number was measured with a microscopic counting chamber and cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. RESULTS: Compared to untreated cells, the total number of cultured human lens epithelial cells was markedly higher after UV irradiation. In a dose-dependent manner, viability was also higher in EGCG-treated cells. CONCLUSIONS: EGCG increased the cell count and cell viability after UV irradiation of cultured human lens epithelial cells, indicating that EGCG can protect lens epithelium against UV damage.

EFFECTS OF (-)EPIGALLOCATECHIN GALLATE AND BLACK TEA POLYPHENOLS ON LIPID METABOLISM RELATED GENE EXPRESSION OF HepG_2 CELLS / 营养学报

Objective: To investigate the effect of (-) epigallocatechin gallate (EGCG) and black tea polyphenols on the lipid metabolism related gene expression profile of human hepatocellular carcinoma HepG2 cells. Method: The total RNA was isolated from HepG2 cells treated with EGCG (5? mol/L), black tea polyphenols (5?g/ml) or 0.1%DMSO (control) for 8 h and was hybridized to Human 14k cDNA microarray for gene expression profile analysis. Real-time RT-PCR was conducted to confirm microarray data. Results: A total of 13 and 29 genes related to lipid metabolism showed differential change after EGCG or black tea polphenols treatment respectively, of which six genes showed consistent expression. The results of real-time PCR were consistent with the microarray data. Conclusion: The mechanism(s) by which EGCG and black tea polyphenols exerts its effects on lipid metabolism are comprehensive. The novel target identified in this study may provide new evidence for further investigation in the hypolipidemic effects of tea polyphenols.

The Effects of Epigallocatechin Gallate on Ultraviolet B Irradiated Cultured Human Skin Fibroblasts / 대한피부과학회지

BACKGROUND: The main polyphenol components in green tee are (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate (EGCG). It is well known that flavonoids such as catechins can be protective against inflammatory and cancer and cardiovascular diseases. These protective effects are largely due to their inhibition of some enzymes and antioxidative activities by scavenging free radicals. Ultraviolet(UV) exposure of the skin, particulary UVB (290-320nm), causes adverse biological effects, including alterations in cutaneous immune cells, photoaging and photocarcinogenesis. Several studies have shown that EGCG afforded protection against UVB-induced inflammatory responses and photocarcinogenesis in murine models. OBJECTIVE AND METHODS: In this study, we investigated the effects of EGCG on UVB irradiated human skin fibroblasts using viability test, thiobarbituric acid assay, propidium iodide(PI) stain, and western blot analyses and RT-PCR. RESULTS: Cell survival curves after UVB irradiation showed dose dependent decrement pattern by trypan blue exclusion assay. Only 42% of dermal fibroblasts survived at 150 mJ/cm2 UVB irradiation. The damage was associated with cell membrane lipid peroxidation, as shown by accumulation malondialdehyde(MDA). By pre-cultivation with EGCG (50nmol), a significant preventive effect was noted on the increase in the absolute number of surviving cells(up to 81.5% of cells survived) and the levels of MDA markedly decreased. Morphological changes associated with apoptotic cell death were easily distinguished by PI stain. Bases on our finding, we investgated the regulation of p53, p21, bax, bcl-2, cyclin D1, E, Cdk2, and PARP proteins by western blot analyses. The expression p53 protein was elevated by following UVB exposure which was inhibited by EGCG treatment. Using RT-PCR, the transcription of p53, fas and jun gene showed similar results which obtained by western blot analyses. CONCLUSION: EGCG, which have newly accepted as a potential UV protection properties, is effective membrane peroxidation inhibitor and prevent apoptotic changes when present in relevant concentration at the site of action beginning and during UVB irradiation. And the protective mechanism of EGCG against UVB-induced cell damage maybe, at least in part, related with p53, fas and jun pathway.

Effects of (-)-Epigallocatechin Gallate (EGCG) on DNA Strand Breaks as Evaluated by Single-cell Gel Electrophoresis (SCG) in Human Lymphocytes

(-)-Epigallocatechin gallate (EGCG), a catechin polyphenol component, is the main ingredient of green tea extract. Although the anti-carcinogenic and cancer inhibitory effects of EGCG have been widely reported, its genotoxicity is not clear and seldom reported. In this study, we examined the effects of EGCG on DNA strand breaks in the isolated lymphocytes and whole blood lymphocytes obtained from two smoking subjects and a nonsmoking healthy subject using a single-cell gel electrophoresis (SCG) assay. The results showed that after 2 hrs of treating the isolated lymphocytes from the smokers, EGCG induced a significant increase in DNA strand breaks at concentrations from 2.5 × 10-5 M to 2.0 × 10-4 M, while after 2 hrs of treating the whole blood obtained from the same smokers, EGCG suppressed the DNA strand breaks in the lymphocytes at concentrations of 1.0 × 10-4 M and 2.0 × 10-4 M. A similar suppressive result was also shown in the whole blood lymphocytes from the nonsmoker at nearly the same concentrations, while at concentrations of 1.0 × 10-3 M or 2.0 × 10-3 M, EGCG induced a significant increase in DNA strand breaks in the whole blood lymphocytes from the nonsmoker. This result suggests that EGCG is not only inhibitory against DNA strand breaks in whole blood, but also genotoxic to the isolated or whole blood lymphocytes at high concentrations. Thus, more research is needed to comprehensively assess the effects of EGCG on genetic materials.

Inhibitory effects of green-tea polyphenol on inflammatory agents in gingival epithelial cells / 实用口腔医学杂志

Objective:To study the effects of green-tea polyphenol, (epigallocatechin gallate,EGCg) on the cellular inflammatory responses of gingival epithelial cells. In order to find out a safe and efficient inflammation-inhibitor for periodontitis prevention and treatment. Methods:A model of cellular inflammatory responses of gingival epithelial cells stimulated by Porphyromonas gingivalis vesicles in vitro was established. The effects of EGCg on PGE2 production of gingival epithelial cells was detected by ELISA. Further more, the effects of EGCg on COX (cyclooxygenase)-2 and MMP (matrix metalloproteinase)-3 mRNA expression were determined by Real-time RT-PCR. Results:EGCg dose-dependently inhibited PGE2 production and COX-2, MMP-3 mRNA expressions. Conclusion:EGCg has inhibitory effects on cellular inflammatory responses of gingival epithelial cells and possesses the potentiality to be a periodontal inflammation-inhibitor.