Effects of (-)-Epigallocatechin gallate on some protein factors involved in the epidermal growth factor receptor signaling pathway

（-）-Epigallocatechin gallate （EGCG）, a major polyphenolic constituent of green tea, can inhibit activity of specific receptor tyrosine kinases （RTKs） and related downstream signal transduction pathways, resulting in the control of unwanted cell proliferation. The epidermal growth factor receptor （EGFR） signaling pathway is one of the most important pathways that regulates growth, survival,proliferation and differentiation in mammalian cells. This review addresses the effects of EGCG on some protein factors involved in the EGFR signaling pathway in a direct or indirect manner. Based on our understanding of the interaction between EGCG and these factors, and based on their structures, EGCG could be used as a lead compound for designing and synthesizing novel drugs with significant biological activity.

Electrochemical properties of La_(0.8)Sr_(0.2)FeO_(3-δ) based composite cathode for intermediate temperature SOFC

La0.8Sr0.2FeO3-δ is a new kind of cathode material for intermediate SOFC, but its electrochemical activity is relative poor for the lanthanum gallate based solid oxide fuel cell. In this paper, a novel composite cathode of La0.8Sr0.2FeO3-δ/La0.9Sr0.1Ga0.8Mg0.2O3-δ was prepared on the LSGM electrolyte substrate by screen-printing method. The results of cathodic polarization measurements show that the overpotential decreases significantly when the composite cathode is used instead of the La0.8Sr0.2FeO3-δ single layer cathode. The cathodic overpotential of the composite La0.8Sr0.2FeO3-δ/La0.9Sr0.1Ga0.8Mg0.2O3-δ cathode is 150 mV at the current density of 0.2 A·cm-2 at 800 ℃, while the cathodic overpotential of the La0.8Sr0.2FeO3-δ single layer cathode is higher than 260 mV at the same condition. The electrochemical impedance spectroscopy was employed to investigate the polarization resistance of the cathode. The polarization resistance of the composite cathode is 1.20 Ω·cm2 in open circuit condition, while the value of the single La0.8Sr0.2FeO3-δ cathode is 1.235 Ω·cm2.

(-)-Epicatechin gallate serves as a novel new delhi metallo-β-lactamase-1(NDM-1)inhibitor

Theβ-lactam antibiotic resistance caused by NDM-1 has become a major crisis of global public health.We have previously screened out(-)-epicatechin gallate(ECG)as a potent NDM-1 inhibitor.We further discussed its inhibitory effect and action mode in the present study.According to our results,ECG reversibly inactivated NDM-1 in a non-competitive mode,with an IC50 value of 4.48μM.ECG effectively recovered the activity of severalβ-lactam antibiotics against resistant strain harboring blaNDM-1.Especially,the effects on carbapenems were worth mentioning.The zinc supplement assay indicated a zinc-related mechanism of ECG.Different from traditional chelating agents,it showed low toxicity both in vivo and in vitro.In a word,our findings provided a promising NDM-1 inhibitor,ECG,which was able to assist carbapenems against NDM-1-producing strain.

Surface molecularly imprinted polymers for solid-phase extraction of （-）-epigallocatechin gallate from toothpaste

Surface molecularly imprinted polymers （SMIPs） have been synthesized to selectively determine （-）-epigallocatechin gallate in aqueous media. SMIPs were prepared using a surface grafting copolymerization method on a functionalized silica gel modified with β-cyclodextrin and vinyl groups. The morphology and composition of the SMIPs were investigated by scanning electron microscopy, Fourier transform-infrared spectroscopy and thermogravimetric analysis. In addition, the molecular binding capacity, recognition properties and selectivity of the SMIPs were evaluated. The imprinted polymers were found to have a highly specific recognition and binding capacity for aqueous media which is （-）-epigallocatechin gallate in the result of the hydrophobic properties of the β-cyclodextrin and the hydrogen-bonding interactions of methacrylic acid. The SMIPs were successfully employed as solid-phase extraction adsor- bents prior to the HPLC determination of （-）-epigallocatechin gallate in toothpaste. The HPLC analysis had a linear dynamic range of 0.5-50.0 μg·mL^-1 with a correlation coefficient of 0.9998 and the recoveries ranged from 89.4% to 97.0% with relative standard deviations less than 4.8%. The limit of detection and limit of quantification were 0.17 and 0.33 μg·mL^-1, respectively. The method provides a promising approach for the preparation of selective materials for the purification and determination of complex samples.

A Novel Flavane from Carapa guianensis

Seven compounds were isolated from the EtOH extraction of the twig of Carapa guianensis Aubl. (Meliaceae). On the basis of spectroscopic methods, their structures were elucidated as (-)-epicatechin-3-O-(3' , 5'-di-O-methyl) gallate (1), (-)-catechin (2), sciadopitysin (3), cleomiscosin B (4), photogedunin (5), chisocheton compound F (6) and odoratone (7), respectively. Among them compound 1 was a new flavane, compounds 2-7 were firstly obtained from this plant, and compound 5 was assigned the C-13-NMR data for the first time. Compound 7 exhibited strong antifeedant activity against Pieris brassicae, and compound 2 exhibited moderate activity, while the n-BuOH portion showed weak activity.

Molecular mechanisms of chemopreventive phytochemicals against gastroenterological cancer development

Cancer is one of the leading causes of death worldwide.Commonly used cancer treatments,including chemotherapy and radiation therapy,often have side effects and a complete cure is sometimes impossible.Therefore,prevention,suppression,and/or delaying the onset of the disease are important.The onset of gastroenterological cancers is closely associated with an individual's lifestyle.Thus,changing lifestyle,specifically the consumption of fruits and vegetables,can help to protect against the development of gastroenterological cancers.In particular,naturally occurring bioactive compounds,including curcumin,resveratrol,isothiocyanates,(-)-epigallocatechin gallate and sulforaphane,are regarded as promising chemopreventive agents.Hence,regular consumption of these natural bioactive compounds found in foods can contribute to prevention,suppression,and/or delay of gastroenterological cancer development.In this review,we will summarize natural phytochemicals possessing potential antioxidant and/or anti-inflammatory and anti-carcinogenic activities,which are exerted by regulating or targeting specific molecules against gastroenterological cancers,including esophageal,gastric and colon cancers.

The epigallocatechin gallate derivative Y_6 reverses drug resistance mediated by the ABCB1 transporter both in vitro and in vivo

Previously, we reported that Y_6, 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_6 in reversing drug resistance both in vitro and in vivo by determining its effect on the adenosine triphosphate-binding cassette protein B1 transporter(ABCB1 or P-glycoprotein, P-gp). Our results showed that Y_6 significantly sensitized cells overexpressing the ABCB1 transporter to anticancer drugs that are ABCB1 substrates. Y_6 significantly stimulated the adenosine triphosphatase activity of ABCB1. Furthermore, Y_6 exhibited a higher docking score as compared with epigallocatechin gallate inside the transmembrane domain of ABCB1. In addition, in the nude mousetumor xenograft model, Y_6(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_6 significantly reversed ABCB1-mediated multidrug resistance and its mechanisms of action may result from its competitive inhibition of the ABCB1 drug efflux function.

Long Non-coding RNAs Expression Profile in HepG2 Cells Reveals the Potential Role of Long Non-coding RNAs in the Cholesterol Metabolism

Background：Green tea has been shown to improve cholesterol metabolism in animal studies,but the molecular mechanisms underlying this function have not been fully understood.Long non-coding RNAs （lncRNAs） have recently emerged as a major class of regulatory molecules involved in a broad range of biological processes and complex diseases.Our aim was to identify important lncRNAs that might play an important role in contributing to the benefits of epigallocatechin-3-gallate （EGCG） on cholesterol metabolism.Methods：Microarrays was used to reveal the lncRNA and mRNA profiles in green tea polyphenol（-）-epigallocatechin gallate in cultured human liver （HepG2） hepatocytes treated with EGCG and bioinformatic analyses of the predicted target genes were performed to identify lncRNA-mRNA targeting relationships.RNA interference was used to investigate the role of lncRNAs in cholesterol metabolism.Results：The expression levels of 15 genes related to cholesterol metabolism and 285 lncRNAs were changed by EGCG treatment.Bioinformatic analysis found five matched lncRNA-mRNA pairs for five differentially expressed lncRNAs and four differentially expressed mRNA.In particular,the lncRNA4 T102202 and its potential targets mRNA-3-hydroxy-3-methylglutaryl coenzyme A reductase （HMGCR） were identified.Using a real-time polymerase chain reaction technique,we confirmed that EGCG down-regulated mRNA expression level of the HMGCR and up-regulated expression ofAT102202.After AT102202 knockdown in HepG2,we observed that the level of HMGCR expression was significantly increased relative to the scrambled small interfering RNA control （P 〈 0.05）.Conclusions：Our results indicated that EGCG improved cholesterol metabolism and meanwhile changed the lncRNAs expression profile in HepG2 cells.LncRNAs may play an important role in the cholesterol metabolism.

Biocompatible and biodegradable nanoparticles for enhancement of anti-cancer activities of phytochemicals

Many phytochemicals show promise in cancer prevention and treatment, but their low aqueous solubility, poor stability, unfavorable bioavailability, and low target specificity make administering them at therapeutic doses unrealistic. This is particularly true for(-)-epigallocatechin gallate, curcumin, quercetin, resveratrol, and genistein. There is an increasing interest in developing novel delivery strategies for these natural products. Liposomes, micelles, nanoemulsions, solid lipid nanoparticles, nanostructured lipid carriers and poly(lactide-co-glycolide) nanoparticles are biocompatible and biodegradable nanoparticles. Those nanoparticles can increase the stability and solubility of phytochemicals, exhibit a sustained release property, enhance their absorption and bioavailability, protect them from premature enzymatic degradation or metabolism, prolong their circulation time, improve their target specificity to cancer cells or tumors via passive or targeted delivery, lower toxicity or side-effects to normal cells or tissues through preventing them from prematurely interacting with the biological environment, and enhance anti-cancer activities. Nanotechnology opens a door for developing phytochemical-loaded nanoparticles for prevention and treatment of cancer.

自由基清除剂对仔猪生长及血液氧化代谢相关指标的影响

活性氧自由基是体内一种重要的信号分子,能参与能量稳态、免疫和信号传导过程。过多的活性氧自由基可造成细胞和组织的损坏,从而引起多种疾病。为研究自由基清除剂对仔猪采食、生长发育和代谢的影响,本研究首先采用二苯基苦基苯肼自由基(DPPH法)比较了维生素C、没食子儿茶素没食子酸酯(Epigallocate-chin gallate,EGCG)。