Cytotoxicity of epigallocatechin-3-gallate to LNCaP cells in the presence of Cu^2＋

Epigallocatechin-3-gallate (EGCG) has shown remarkably anti-cancer activity, with its bioactivity being related to reactive conditions, such as pH and metal ions. The present study investigated the degradation of EGCG and its effect on prostate cancer cell in the presence of Cu2 . EGCG was incubated with prostate cancer cells,     

Green tea polyphenol,epigallocatechin-3-gallate,possesses the antiviral activity necessary to fight against the hepatitis B virus replication in vitro

Although several antiviral drugs and vaccines are available for use against hepatitis B virus (HBV), hepatitis caused by HBV remains a major public health problem worldwide, which has not yet been resolved, and new anti-HBV drugs are in great demand. The present study was performed to investigate the anti-HBV activity of epigallocatechin-3-gallate (EGCG), a natural-origin compound, in HepG2 2.2.15 cells. The antiviral activity of EGCG was examined by detecting the levels of HBsAg and HBeAg in the supernatant and extracellular HBV DNA. EGCG effectively suppressed the secretion of HBsAg and HBeAg from HepG2 2.2.15 cells in a dose- and time-dependent manner, and it showed stronger effects at the level of 0.11–0.44 μmol/ml (50–200 μg/ml) than lamivudine (3TC) at 0.87 μmol/ml (200 μg/ml). EGCG also suppressed the amount of extracellular HBV DNA. The data indicated that EGCG possessed anti-HBV activity and suggested the potential of EGCG as an effective anti-HBV agent with low toxicity.     

Synergistic effects of tea polyphenols and ascorbic acid on human lung adenocarcinoma SPC-A-1 cells

Tea polyphenols have been shown to have anticancer activity in many studies.In the present study,we investigated effects of theaflavin-3-3'-digallate(TF3),one of the major theaflavin monomers in black tea,in combination with ascorbic acid(AA),a reducing agent,and(-)-epigallocatechin-3-gallate(EGCG),the main polyphenol presented in green tea,in combination with AA on cellular viability and cell cycles of the human lung adenocarcinoma SPC-A-1 cells.The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) assay showed that the 50% inhibition concentrations(IC50) of TF3,EGCG,and AA on SPC-A-1 cells were 4.78,4.90,and 30.62 μmol/L,respectively.The inhibitory rates of TF3 combined with AA(TF3+AA) and EGCG combined with AA(EGCG+AA) at a molar ratio of 1:6 on SPC-A-1 cells were 54.4% and 45.5%,respectively.Flow cytometry analysis showed that TF3+AA and EGCG+AA obviously increased the cell population in the G0/G1 phase of the SPC-A-1 cell cycle from 53.9% to 62.8% and 60.0%,respectively.TF3-treated cells exhibited 65.3% of the G0/G1 phase at the concentration of its IC50.Therefore,TF3+AA and EGCG+AA had synergistic inhibition effects on the proliferation of SPC-A-1 cells,and significantly held SPC-A-1 cells in G0/G1 phase.The results suggest that the combination of TF3 with AA or EGCG with AA enhances their anticancer activity.     

EGCG对肝癌细胞株BEL-7402增殖凋亡及Stat3蛋白表达的影响

研究了没食子儿茶素没食子酸酯（EGCG）对人肝癌细胞BEL-7402增殖凋亡及对信号转导蛋白和转录激活因子3（Stat3）蛋白及磷酸化Stat3蛋白表达的影响.应用MTT法检测不同浓度EGCG对BEL-7402细胞增殖的抑制作用,用流式细胞仪分析细胞的凋亡率,用ELISA方法检测EGCG对Stat3蛋白及磷酸化的Stat3蛋白表达的影响.结果表明：EGCG有抑制肝癌细胞增殖促进凋亡的作用,并呈剂量依赖性.ELISA结果显示EGCG能降低磷酸化Stat3蛋白的表达水平.EGCG能抑制肝癌细胞的增殖促进凋亡,其机制可能有与下调磷酸化的Stat3蛋白的表达有关.     

Differential generation of hydrogen peroxide upon exposure to zinc and cadmium in the hyperaccumulating plant specie （Sedum alfredii Hance）

Sedum alfredii Hance has been identified as zinc (Zn) and cadmium (Cd) co-hyperaccumulator. In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H. were examined, The results show that Zn and Cd contents in the shoots of Sedum alfredii H. treated with 1000 μmol/L Zn2 and/or 200 μmol/L Cd2 increased linearly within 15 d. Contents of total S, glutathione (GSH) and H2O2 in shoots also increased within 15 d, and then decreased. Total S and GSH contents in shoots were higher under Cd2 treatment than under Zn2 treatment. However, reverse trends of H2O2 content in shoots were obtained, in which much higher H2O2 content was observed in Zn2 -treated shoots than in Cd2 -treated shoots. Similarly, the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn2 -treated leaf than in the Cd2 -treated one. These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn2 and Cd2 for the hyperaccumulator Sedum alfredii H. And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves. Oar results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2.     

Heat shock protein 90 protects rat mesenchymal stem cells against hypoxia and serum deprivation-induced apoptosis via the PI3K/Akt and ERK1/2 pathways

Mesenchymal stem cell(MSC)transplantation has shown a therapeutic potential to repair the ischemic and infracted myocardium,but the effects are limited by the apoptosis and loss of donor cells in host cardiac microenvironment.The aim of this study is to explore the cytoprotection of heat shock protein 90(Hsp90)against hypoxia and serum deprivation-induced apoptosis and the possible mechanisms in rat MSCs.Cell viability was determined by3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay.Apoptosis was assessed by Hoechst 33258nuclear staining and flow cytometric analysis with annexin V/PI staining.The gene expression of Toll-like receptor-4(TLR-4)and V-erb-b2 erythroblastic leukemia viral oncogene homolog 2(ErbB2)was detected by real-time polymerase chain reaction(PCR).The protein levels of cleaved caspase-3,Bcl-2,Bcl-xL,Bax,total-ERK,phospho-ERK,totaI-Akt,phospho-Akt,and Hsp90 were detected by Western blot.The production of nitric oxide was measured by spectrophotometric assay.Hsp90 improves MSC viability and protects MSCs against apoptosis induced by serum deprivation and hypoxia.The protective role of Hsp90 not only elevates Bcl-2/Bax and Bcl-xL/Bax expression and attenuates cleaved caspase-3 expression via down-regulating membrane TLR-4 and ErbB2 receptors and then activating their downstream PI3K/Akt and ERK1/2 pathways,but also enhances the paracrine effect of MSCs.These findings demonstrated a novel and effective treatment strategy against MSC apoptosis in cell transplantation.     

Overexpression of the steroidogenic acute regulatory protein increases the expression of ATP-binding cassette transporters in microvascular endothelial cells (bEnd.3)

Objective:To determine the effect of steroidogenic acute regulatory protein(StAR) overexpression on the levels of adenosine triphosphate(ATP)-binding cassette transporter A1(ABCA1) and ATP-binding cassette transporter G1(ABCG1) in an endothelial cell line(bEnd.3).Methods:The StAR gene was induced in bEnd.3 cells with adenovirus infection.The infection efficiency was detected by fluorescence activated cell sorter(FACS) and fluorescence microscopy.The expressions of StAR gene and protein levels were detected ...     

Al2O3颗粒对丁腈橡胶/316L不锈钢配副摩擦磨损行为的影响

目的：研究弹性体/金属配副在硬质颗粒环境下的摩擦磨损行为,分析有无颗粒及颗粒尺寸大小对摩擦学特性的影响,为橡塑密封设计提供参考。创新点：基于橡胶O型圈常见失效机制,模拟橡胶密封圈在颗粒介入时的摩擦磨损行为,探讨硬质颗粒及其颗粒尺寸对橡胶/金属摩擦配副的影响。方法：1.采用球/平面接触方式,开展丁腈橡胶/金属（316L）配副在Al2O3颗粒环境下的摩擦磨损行为,通过考察摩擦系数时变曲线、摩擦副磨损形貌及其损伤机制等特性,揭示 Al2O3颗粒对丁腈橡胶/316L不锈钢配副摩擦磨损行为的影响。结论：1. Al2O3颗粒进入橡胶/金属摩擦配副明显降低摩擦系数、硬质颗粒的犁削作用,加剧金属偶件的磨损;2.大尺寸的Al2O3颗粒能嵌入橡胶基体并加速橡胶的磨损,对金属有微切屑作用;然而随着颗粒尺寸的减小,颗粒反而减缓橡胶的磨损;3.在有无颗粒和不同颗粒尺寸的情况下,橡胶和金属均表现出不同的损伤机制。     

电导法测定298K时NdCl3在DMF和H2O中的活度系数

应用电导法在298K时测定了稀土氯化盐NdCl3在混合溶剂(DMF-H2O)中的电导率;利用公式计算了NdCl3的摩尔电导率;应用Kohlraush经验规则,使用Origin软件进行线性拟合,外推得到298K时NdCl3在混合溶剂(DMF-H2O)中的无限稀释摩尔电导率λ0 =300.01 (S*cm2 *mol-1);应用Debye-Hücker 和Osager-Falkenhangen公式计算了NdCl3在混合溶剂(DMF-H2O)中的活度系数,并讨论了在298K时浓度对稀土盐NdCl3溶液活度系数的影响,随稀土氯化盐溶液浓度的增加,稀土盐溶液的活度系数降低.