Addition Of Epigallocatechin-3-gallate Research Articles

The gelation properties of myofibrillar proteins prepared with malondialdehyde and (−)-epigallocatechin-3-gallate

Impact of malondialdehyde (MDA) and (−)-Epigallocatechin-3-gallate (EGCG) on gelling properties of myofibrillar proteins (MPs) was investigated. Addition of 6 mM MDA enhanced molecular interactions of proteins, thus the strength and elastic modulus (G′) of gel were improved. EGCG addition aggravated gel quality deterioration due to further modification of MPs induced by EGCG. Addition of 12 mM MDA jeopardized gel quality according to the increasing of strength and G′, but the decreasing of water-holding capacity (WHC), and the collapse of microstructure. Nevertheless, EGCG reacted with MDA forming EGCG-MDA adducts, hence improved gel quality, which was supported by the decreasing of strength, but the increasing of WHC, and the repaired microstructure of gel at 12 mM MDA. Addition of 24 mM MDA severely jeopardized gel quality, which became even worse due to EGCG addition. This work is helpful to understand the impact of MDA and polyphenols on the gel-forming capacity of MPs.

Molecular interaction of soybean glycinin and β-conglycinin with (−)-epigallocatechin gallate induced by pH changes

The effect of pH on interactions of soybean glycinin (11S) and β-conglycinin (7S) with (−)-epigallocatechin- 3-gallate (EGCG) were determined by turbidity. Results confirmed that the protein structure and interactions of 11S and 7S with EGCG depended largely on the pH. The binding affinity between 11S, 7S proteins and EGCG was strongest at pH 7.0 among the three pH levels and 7S showed a greater affinity to EGCG compared to 11S. The interaction mechanisms and structures of 11S-EGCG and 7S-EGCG complexes were further determined by multiple spectroscopic technique and molecular docking. Results showed that EGCG induced changes in the microenvironment of tryptophan, tyrosine, and C–H bending vibration at different pH levels. Binding to EGCG altered the secondary structures of the 11S and 7S proteins, inducing an increase in β-sheet at the cost of α-helix at pH7.0 and α-helix at pH5.0, respectively. The 11S and 7S presented more compact microstructure with the addition of EGCG. Electrostatic interaction, hydrogen bonding and hydrophobic interaction were all involved in the formation of complexes, where the hydrogen bond was the dominant one. These results might be helpful for the development of 11S-EGCG and 7S-EGCG as a bioactive food additive in the food industry.

The Effect of (-)-Epigallocatechin-3-Gallate Non-Covalent Interaction with the Glycosylated Protein on the Emulsion Property.

The effect of (−)-epigallocatechin-3-gallate (EGCG) on protein structure and emulsion properties of glycosylated black bean protein isolate (BBPI-G) were studied and compared to native black bean protein isolate (BBPI). The binding affinity of BBPI and BBPI-G with EGCG belonged to non-covalent interaction, which was determined by fluorescence quenching. EGCG attachment caused more disordered protein conformation, leading to a higher emulsification property. Among the different EGCG concentrations (0.10, 0.25, 0.50 mg/mL), the result revealed that the highest level of the emulsification property was obtained with 0.25 mg/mL EGCG. Therefore, the BBPI-EGCG and BBPI-G-EGCG prepared by 0.25 mg/mL EGCG were selected to fabricate oil-in-water (O/W) emulsions. After the addition of EGCG, the mean particle size of emulsions decreased with the increasing absolute value of zeta-potential, and more compact interfacial film was formed due to the higher percentage of interfacial protein adsorption (AP%). Meanwhile, EGCG also significantly reduced the lipid oxidation of emulsions.

Combination of 5-Florouracil and polyphenol EGCG exerts suppressive effects on oral cancer cells exposed to radiation

ObjectiveNatural compounds such as epigallocatechin-3-gallate (EGCG) have previously shown chemotherapeutic properties with few side-effects. In our study, we evaluated the effects of combining EGCG with 5-fluorouracil (5-FU) and radiotherapy on oral squamous cell cancer. We evaluated whether the combination of lower doses of 5-FU with EGCG could be equally or more effective than the use of higher doses of 5-FU alone. MethodsCell viability, migration and cell cycles were assayed in oral cancer cell lines treated with 5-FU, 5-FU + EGCG and radiation (0, 2.5 and 5 Gy). ResultsThis study found that the combination of EGCG with 5-FU reduced cell viability and migration distance compared to control samples and the same dose of 5-FU alone. Addition of EGCG increased the number of cells in the G2/M phase, while 5-FU arrested the cell cycle in phase S. Moreover, cell exposure to 5 Gy radiation decreased the effects of combining with EGCG. ConclusionsIn summary, the combination of EGCG and 5-FU reduced both cell viability and migration as well as altered the cell cycle to a greater extent than 5-FU alone.

(-)-Epigallocatechin-3-gallate-mediated formation of myofibrillar protein emulsion gels under malondialdehyde-induced oxidative stress

The quality of meat products is influenced by protein oxidation. Understanding the effects of antioxidant polyphenols and oxidizing lipoperoxides on myofibrillar proteins is essential for controlling the quality of meat products. This study was designed to investigate the epigallocatechin-3-gallate (EGCG)-mediated formation of myofibrillar protein emulsion gels under malondialdehyde (MDA)-induced oxidative stress. Low MDA concentrations (3 and 6 mM) improved the water-holding capacity, strength, elasticity, and emulsifying properties of gels due to the enhanced protein-protein interactions via MDA. The addition of EGCG reduced the overall properties of the emulsion gel due to further modification of the proteins. At a high concentration of MDA (12 mM), there was excessive cross-linking and unfolding of myofibrillar proteins, which led to a compact gel structure, and reduced the overall properties of the gel. In this situation, the addition of EGCG protected myofibrillar proteins from modifications induced by MDA and improved the quality of emulsion gels.

176 Effect of epigallocatechin-3-gallate on bovine oocyte in vitro maturation, fertilization, and development

Epigallocatechin-3-gallate (EGCG) is a major ingredient of catechin polyphenols, and a strong antioxidant compound. Huang et al. (2018 Asian-australas. J. Anim. Sci.) reported that adding 50μM EGCG can improve the bovine oocyte maturation rate. In this research, we investigated the effect of EGCG supplementation on different periods in bovine IVF. Cumulus-oocyte complex (COC) collected from ovaries of slaughtered cows were cultured in maturation medium (20 to 30 oocytes per 100-µL droplet), which consisted of TCM-199 with Earle’s salts and 25mM HEPES supplemented with 10% (vol/vol) fetal bovine serum (FBS), 1µg mL−1 oestradiol, 0.02mg mL−1 FSH, and antibiotics at 38.5°C in a humidified atmosphere of 5% CO2 in air for 24h (in vitro maturation, IVM). After IVM, COC were fertilized in the fertilization medium (modified Brackett-Oliphant media supplemented with 10 µgmL−1 heparin, 10mM caffeine, and 3mg mL−1 BSA) for 6h using semen of one bull at final sperm concentration of 1×107 mL−1 (IVF). After IVF, COC were denuded and cultured in culture medium [CR1aa supplemented with 10% (vol/vol) FBS and antibiotics] at 38.5°C in a humidified atmosphere of 5% O2, 5% CO2, and 90%N2 for 8 days (in vitro culture, IVC). The EGCG was supplemented at 10, 25, 50, and 100M in IVM medium; 25 and 50 µM in IVF medium; and 50 and 100 µM in IVC medium. After 24h in IVM medium, COC were denuded by pipetting, fixed in 3:1 ethanol:acetic acid for 24h and then checked for nuclear and polar body by using aceto-orcein stain. After 18h in IVF, the pronucleus in zygote was fixed in 3:1 ethanol:acetic acid for 24h and checked by aceto-orcein staining. Embryo development was evaluated by counting the total number of embryos that had reached compacted morula by 6 to 8 days after IVF. Significant differences were analysed by chi-squared test and residual analysis. A P-value<0.05 was considered statistically significant. When EGCG was added to IVM, there was no significant difference of oocyte maturation rate between all concentrations (0v. 10v. 25v. 50v. 100 μM: 73.9% v. 56.7% v. 76.7% v. 72.7% v. 63.5%). When EGCG was added to IVF, there was no significant difference of fertilized rate (0v. 25v. 50 μM: 59.4% v. 73.7% v. 64.9%). When EGCG was added to IVC, there was no significant difference in development rate (0v. 50v. 100 μM: 26.2% v. 15.7% v. 22.0%). In this research, EGCG addition did not affect bovine in vitro fertilization.

Epigallocatechin-3 gallate prevents pressure overload-induced heart failure by up-regulating SERCA2a via histone acetylation modification in mice.

Heart failure is a common, costly, and potentially fatal condition. The cardiac sarcoplasmic reticulum Ca-ATPase (SERCA2a) plays a critical role in the regulation of cardiac function. Previously, low SERCA2a expression was revealed in mice with heart failure. Epigallocatechin-3-gallate (EGCG) can function as an epigenetic regulator and has been reported to enhance cardiac function. However, the underlying epigenetic regulatory mechanism is still unclear. In this study, we investigated whether EGCG can up-regulate SERCA2a via histone acetylation and play role in preventing heart failure. For this, we generated a mouse model of heart failure by performing a minimally invasive transverse aortic constriction (TAC) operation and used this to test the effects of EGCG. The TAC+EGCG group showed nearly normal cardiac function compared to that in the SHAM group. The expression of SERCA2a was decreased at both the mRNA and protein levels in the TAC group but was enhanced in the TAC+EGCG group. Levels of AcH3 and AcH3K9 were determined to decrease near the promoter region of Atp2a2 (the gene encoding SERCA-2a) in the TAC group, but were elevated in the TAC+EGCG group. Meanwhile, HDAC1 activity and binding near the Atp2a2 promoter were increased in the TAC group but decreased with EGCG addition. Further, binding levels of GATA4 and Mef2c near the Atp2a2 promoter region were reduced in TAC hearts, which might have been caused by histone hypoacetylation; this was reversed by EGCG. Together, upregulation of SERCA2a via the modification of histone acetylation plays a role in EGCG-mediated prevention of pressure overload-induced heart failure, and this might represent a novel pharmacological target for the treatment of heart failure.

A Poloxamer-407 modified liposome encapsulating epigallocatechin-3-gallate in the presence of magnesium: Characterization and protective effect against oxidative damage

Epigallocatechin-3-gallate (EGCG) is a polyphenolic catechin from green tea, well known for being bioactive in age-associated pathologies where oxidative stress plays a preeminent role. The activity of this molecule is however contrasted by its high chemical and metabolic instability that determines a poor concentration of the antioxidant within the biological system after administration. In order to protect the molecule and increase its delivery efficiency, we have encapsulated EGCG inside anionic liposomes made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine and cholesteryl hemisuccinate. To maximize EGCG internalization, magnesium salt was added in the preparation. However stable nanodispersions suitable for drug delivery were obtained only after treatment with Poloxamer-407, a polyethylene–propylene glycol copolymer. The structural and morphological properties of the produced dispersion were studied by X-ray diffraction, which showed a multilamellar structure even after EGCG addition and an ordering effect of Poloxamer-407; Dynamic Light Scattering demonstrated serum stability of the liposomes. The characterization was completed by evaluating both encapsulation efficiency (100%, in the final formulation) and in vitro EGCG release. Since oxidative stress is involved in numerous retinal degenerative diseases, such as age-related macular degeneration, the ability of these liposomes to contrast H2O2-induced cell death was assessed in human retinal cells. Morphological changes at the subcellular level were analyzed by Transmission Electron Microscopy, which showed that mitochondria were better preserved in cells treated with liposomes then those treated with free EGCG. In conclusion, the results demonstrated that the produced formulation enhances the efficacy of EGCG under stress conditions, thus representing a potential formulation for the intracellular delivery of EGCG in diseases caused by oxidative damage.

Epigallocatechin-3-gallate reduces damage to osteoblast-like cells treated with Zoledronic acid

Objectiveanalyze the effect of zoledronic acid (ZA) alone and in combination with epigallocatechin-3-gallate (EGCG) on human osteoblast cells. MethodsSAOS-2 osteoblastic phenotype cell line treated with different doses (0.01–10 μM) of ZA or ZA + EGCG underwent cell viability, mineralization, collagen synthesis and cell migration tests. ResultsMicromolar (1 and 5 μM) doses of ZA reduced cell viability (p < 0.001), mineralization (p < 0.001), and collagen synthesis (p < 0.001), while nanomolar doses (0.1 μM) did not produce any effect. EGCG application partly reversed the inhibition produced by ZA, and even increased mineralization (p < 0.001). Conclusionsthe data obtained shows that ZA at micromolar doses produces negative effects on osteoblast at all parameters measured, while at nanomolar levels ZA only affected cell migration and had no other effects on osteoblasts. The addition of EGCG partly reversed the effects produced by ZA, suggesting that this might be a promising preventative measure against BRONJ.

Dentin bonding and physicochemical properties of adhesives incorporated with epigallocatechin-3-gallate

The aim was to assess dentin adhesion and physicochemical properties of experimental etch-and-rinse and self-etch adhesives doped with epigallocatechin-3-gallate (EGCG), a well-known collagen crosslinker obtained from green tea (Camellia sinensis). Experimental adhesives were prepared without (0wt%), with 0.1 or 0.5wt% EGCG addition. Their degree of conversion was surveyed by FTIR, and bar-shaped specimens were tested to obtain flexural strength and modulus initially and after 1-week ethanol storage. Extracted human molars were prepared, bonded, and cut into resin-dentin sticks for microtensile bond strength test, which was conducted after 24h or 6-month water storage. Statistical analyses were performed with two-way ANOVA and Tukey's test (p < 0.05). Degree of conversion outcomes depicted a significant polymerization reduction by the addition of EGCG in self-etch adhesive in both concentrations. However, only 0.1% reduced the conversion of etch-and-rinse adhesive. Flexural modulus and strength were significantly diminished (p < 0.05) by the addition of both concentrations of EGCG for the two model adhesives. Dentin-bond strength was reduced after aging with the addition of EGCG to self-etch adhesive. Nevertheless, 0.5% EGCG increased the bond strength of etch-and-rinse adhesive after aging, conversely to the significant reduction for EGCG-free control adhesive. In conclusion, EGCG at 0.5% provides optimal improvements on dentin bonding without altering final polymerization of a model etch-and-rinse adhesive.

Calorimetric and spectroscopic studies on the competitive behavior between (−)-epigallocatechin-3-gallate and 5-fluorouracil with human serum albumin

The combination of several drugs is often necessary, especially during long-term therapy. Drug-protein interaction has attracted a great deal of research interest because only the free drug fraction exerts pharmacological and/or toxicological effects. Herein, the binding interactions of serum transport protein, human serum albumin (HSA), with individual or combined anticancer drugs, (−)-epigallocatechin-3-gallate (EGCG) and 5-fluorouracil (FU), were investigated using isothermal titration calorimetry (ITC), circular dichroism (CD), and dynamic light scattering (DLS). DLS measurements showed that EGCG has a larger effect on the hydrodynamic diameter of HSA than FU. The adding order of EGCG and FU has an important influence on the size of the EGCG+FU+HSA complex. Fitting of the ITC data suggested that there are two sets of sites for the individual and combined binding of EGCG and FU to HSA. The obtained thermodynamic parameters revealed that electrostatic, hydrogen bonding, and van der Waals interactions may contribute to the stronger affinity of EGCG while hydrophobic interactions, van der Waals forces, and hydrogen bonding are the major forces in stabilizing the FU+HSA complex. The largest free concentrations of EGCG and FU are attained at pH7.4 and 8.4 respectively, due to the pH dependence on the number of binding sites and binding constants. The discrepancy in the free concentration between the binary and ternary systems implies the competitive binding of EGCG and FU to HSA. Changes in the secondary structure of HSA due to the addition of EGCG and FU at different pHs were discussed based on CD measurements. The calorimetric and spectroscopic results can provide quantitative information on the binding characteristics and suggest that the competitive binding of EGCG and FU to HSA may enhance anticancer effects. These results can provide a deeper understanding of combination therapy.

Effect of epigallocatechin-3-gallate on the increase in type II collagen accumulation in cartilage-like MSC sheets.

With the aim to increase type II collagen content in the scaffold-free cartilage-like cell sheet using human bone marrow mesenchymal stem cells, we examined the effect of epigallocatechin-3-gallate (EGCG) addition to the chondrogenic medium for the cell sheet culture. The addition of EGCG (10μM) increased the content of type II collagen 2-fold, while the addition did not markedly change the expression level of the genes encoding type II collagen and Sox 9. The reactive oxygen species level in the cells in cell sheets was thought to be too low to suppress the accumulation of type II collagen. On the other hand, the addition of EGCG markedly decreased both the matrix metalloproteinase-13 concentration in the supernatant of cell sheet culture and the type II collagen degradation activity in that supernatant. Taken together, EGCG may enhance the accumulation of type II collagen by suppressing type II collagen degradation.

Hippocampal Neuroprotection by Minocycline and Epigallo-Catechin-3-Gallate Against Cardiopulmonary Bypass-Associated Injury.

Surgical correction of congenital cardiac malformations mostly implies the use of cardiopulmonary bypass (CPB). However, a possible negative impact of CPB on cerebral structures like the hippocampus cannot be neglected. Therefore, we investigated the effect of CPB on hippocampus CA1 and CA3 regions without or with the addition of epigallocatechin-3-gallate (EGCG) or minocycline. We studied 42 piglets and divided them into six experimental groups: control without or with EGCG or minocycline, CPB without or with EGCG or minocycline. The piglets underwent 90 minutes CPB and subsequently, a 120-minute recovery and reperfusion phase. Thereafter, histology of the hippocampus was performed and the adenosine triphosphate (ATP) content was measured. Histologic evaluation revealed that CPB produced a significant peri-cellular edema in both CA regions. Moreover, we found an increased number of cells stained with markers for hypoxia, apoptosis and nitrosative stress. Most of these alterations were significantly reduced to or near to control levels by application of EGCG or minocycline. ATP content was significantly reduced within the hippocampus after CPB. This reduction could not be antagonized by EGCG or minocycline. In conclusion, CPB had a significant negative impact on the integrity of hippocampal neural cells. This cellular damage could be significantly attenuated by addition of EGCG or minocycline.

Binding of (−)-epigallocatechin-3-gallate with thermally-induced bovine serum albumin/ι-carrageenan particles

Novel thermally-induced BSA/ι-carrageenan particles are used as a protective carrier for (−)-epigallocatechin-3-gallate (EGCG). The addition of EGCG to BSA/ι-carrageenan particles can highly quench the intrinsic fluorescence of BSA, which is explained in terms of the binding of EGCG to the hydrophobic pockets of BSA mainly through the hydrophobic force. According to the double logarithm equation, the binding constant is determined as 1.1×108M−1 for the binding of EGCG with BSA/ι-carrageenan particles. The high binding affinity is ascribed to both the molecular structure of EGCG and the partial unfolding state of BSA in BSA/ι-carrageenan particles. The circular dichroism spectra and calculated α-helix of BSA suggest that the bound EGCG leads to a more random secondary structure of BSA. Furthermore, BSA/ι-carrageenan particles are found to be superior to native BSA and pure BSA particles for improving the stability and radical scavenging activity of EGCG.

Epigallocatechin‐3‐Gallate Attenuates Porphyromonas gingivalis Lipopolysaccharide‐Enhanced Matrix Metalloproteinase‐1 Production Through Inhibition of Interleukin‐6 in Gingival Fibroblasts

Recent studies have shown that epigallocatechin-3-gallate (EGCG), a major constituent of green tea extract, exhibits effects of anti-inflammation and antioxidation on periodontal inflammation. The present in vitro study examines the effect of EGCG on Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS)-enhanced expression of interleukin (IL)-6 and matrix metalloproteinase (MMP)-1, as well as the activation of nuclear factor-kappa B (NF-κB). Furthermore, the role of IL-6 on LPS-enhanced MMP-1 production is evaluated using human gingival fibroblasts (HGFs). HGFs were primary cultured from human gingiva specimens. The cytotoxicities of EGCG and LPS were tested by cell viability tests. The cellular mRNA expression of IL-6 was determined by reverse-transcription polymerase chain reaction, and the protein expression of MMP-1 and IL-6 was examined by enzyme-linked immunosorbent assay. The cytosol expression and nuclear translocation of NF-κB was evaluated by immunocytochemistry followed by confocal laser scanning microscopy. Pg LPS significantly increased MMP-1 production in HGFs, whereas adding EGCG significantly attenuated this enhanced production of MMP-1. LPS treatment also increased the mRNA and protein expression of IL-6 and stimulated NF-κB activation in HGFs. However, the addition of EGCG significantly attenuated the IL-6 expression and NF-κB activation. Supplemental addition of IL-6 significantly enhanced cellular MMP-1 production, whereas anti-IL-6 antibody inhibited LPS-enhanced MMP-1 production. EGCG could attenuate Pg LPS-enhanced production of MMP-1 in HGFs, whereas this attenuation might be due to the inhibition of IL-6 by EGCG.

The green tea polyphenol (−)-epigallocatechin-3-gallate inhibits magnesium binding to the C-domain of cardiac troponin C

Cardiac muscle contraction is activated via the single Ca(2+)-binding site (site II) in the N-domain of troponin C (cTnC). The two Ca(2+)/Mg(2+) binding sites in the C-domain of cTnC (sites III and IV) have been considered to play a purely structural role in anchoring cTnC to the thin filament. However, several recent discoveries suggest a possible role of this domain in contractile regulation. The green tea polyphenol (-)-epigallocatechin 3-gallate (EGCg), which binds specifically to the C-domain of cTnC, reduces cardiac myofilament Ca(2+) sensitivity along with maximum force and acto-myosin ATPase activity. We have determined the effect of EGCg on Ca(2+) and Mg(2+) binding to the C-domain of cTnC. In the absence of Mg(2+) there was no significant effect of EGCg on the Ca(2+)-cTnC affinity. Surprisingly, in the presence of Mg(2+) EGCg caused an increase in Ca(2+) affinity for sites III and IV of cTnC. However, in the absence of Ca(2+) the addition of EGCg caused a significant reduction in Mg(2+)-cTnC affinity. This reduction is presumably responsible for the increase in Ca(2+)-cTnC affinity produced by EGCg in the presence of Mg(2+). We propose that the inhibitory effect of EGCg on myofilament Ca(2+) activation may be related to an enhanced Ca(2+)-Mg(2+)exchange at sites III and IV of cTnC, which might reduce the myosin crossbridge dependent component of thin filament activation.

Radioprotective effects of (-)-epigallocatechin-3-gallate on human erythrocyte/granulocyte lineages

Epigallocatechin-3-gallate (EGCg) is widely recognised as a powerful antioxidant and free radical scavenger. This study examined the radioprotective effects of EGCg on human granulopoiesis and erythropoiesis. Highly purified human CD34(+) haematopoietic stem/progenitor cells were prepared from human placental/umbilical cord blood. The cells were exposed to X rays at a dose rate of ∼1 Gy min(-1) and then cultured in a medium supplemented with either granulocyte colony-stimulating factor (G-CSF) or erythropoietin (EPO). EGCg (100 nM) was added to the culture immediately before or after X-irradiation. The concentration of 100-nM EGCg was determined in the authors' previous study. The number of granulocyte and erythrocyte colonies generated by X-irradiated CD34(+) cells decreased in a dose-dependent manner. Although EGCg addition yielded an ∼2-fold increase in the proliferation of each haematopoietic progenitor, no significant protective effect was observed in the surviving fraction of granulocyte progenitors (G-CSF alone: D(0)=1.06 Gy, n=1.14). However, EGCg addition before or after irradiation conferred a significantly higher protective effect on erythrocyte colony formation compared with the control (EPO alone: D(0)=0.66 Gy, n=1.56; EGCg (before): D(0)=0.43 Gy, n=5.48). EGCg addition before irradiation significantly improved the survival of erythroid progenitors subjected to radiation of <1 Gy. These results suggest that EGCg is more protective of erythropoiesis than granulopoiesis from radiation damage.

Epigallocatechin-3-gallate (EGCG) enhances the therapeutic activity of a dental adhesive

ObjectivesThe purpose of this study was to evaluate the antibacterial potential and physicochemical properties of a dental adhesive incorporated with epigallocatechin-3-gallate (EGCG) in different concentration over time. MethodsEGCG was incorporated at a ratio of 100, 200, and 300μg/ml into a dental adhesive. The effects of the cured adhesives on the growth of Streptococcus mutans were determined by direct contact test immediately or one month later and by scanning electron microscopy (SEM), respectively. Microtensile bond strength (μTBS) test was used to test the mechanical property of the adhesives immediately or six months later. The degree of conversion (DC) of the adhesives was evaluated by Fourier Transform Infrared Spectroscopy (FTIR). ResultsCompared with negative control, the 200μg/ml and 300μg/ml EGCG-incorporated dental adhesive were found to exhibit inhibitory effect on the growth of S. mutans. The μTBS of the EGCG-incorporated dental adhesive was higher than the control. The DC of the adhesive system was not affected by the addition of EGCG. Conclusions200μg/ml EGCG incorporated dental adhesives could accomplish therapeutic goals that play in antimicrobial function whilst keeping the durability of resin–dentine bond.

Effect of (−)-epigallocatechin-3-gallate on human insulin fibrillation/aggregation kinetics

(−)-Epigallocatechin-3-gallate (EGCG), a food additive derived from green tea, has been reported to effectively inhibit the fibrillation of many amyloid proteins, but not insulin. So herein, the influences of EGCG on the fibrillation kinetics of human insulin at two conditions (pH 2.0, 60°C and pH 7.4, 37°C) were extensively studied. It was found that at pH 2.0 and 60°C the inhibitory effect increased with increasing EGCG concentration from 0.35 to 3.5mmol/L but kept almost unchanged from 3.5 to 5mmol/L EGCG. The addition of EGCG reduced the length and width of fibrils and kept part of insulin from fibrillation at this condition. At pH 7.4 and 37°C, however, EGCG altered the fibrillation pathway of insulin and redirected it into globular aggregates, and the inhibitory effect of EGCG on the aggregation reached maximum at about 0.1–0.2mmol/L. In this case, part of insulin molecules were prevented from aggregation and existed as a mixture of monomer, dimer, tetramer, and hexamer in the solution. Circular dichroism spectroscopy indicated that EGCG slowed down the changes of the secondary structures of insulin in the aggregation. Finally, two physical models were proposed to explain the molecular interactions between insulin and EGCG at the two conditions. The research has clarified the kinetic mechanism of the inhibitory effect of EGCG on insulin fibrillation/aggregation.

EGCG protects against oxidized LDL-induced endothelial dysfunction by inhibiting LOX-1-mediated signaling

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), originally identified as the major receptor for oxidized low-density lipoprotein (oxLDL) in endothelial cells, plays a major role in the pathology of vascular diseases. Green tea consumption is associated with reduced cardiovascular mortality in some epidemiological studies. In the present study, we hypothesized that the most abundant polyphenolic compound in tea, epigallocatechin-3-gallate (EGCG), can downregulate parameters of endothelial dysfunction by modulating LOX-1-regulated cell signaling. In cultured human umbilical vein endothelial cells (HUVECs), exposure to oxLDL (130 microg/ml), which led to an increase in LOX-1 expression at the RNA and protein levels, was abrogated by addition of EGCG or DPI, a well-known inhibitor of flavoproteins, suggesting the involvement of NADPH oxidase. Furthermore, oxLDL rapidly activated the membrane translocation of Rac-1 and p47phox and the subsequent induction of ROS generation, which was suppressed markedly by pretreatment with EGCG or anti-LOX-1 monoclonal antibody. OxLDL also increased p38 MAPK phosphorylation and decreased phosphorylation of the amino-terminal region of Akt, with maximal induction at about 30 min, and NF-kappaB phosphorylation within 1 h, resulting in redox-sensitive signaling. In addition, oxLDL diminished the expression of endothelial nitric oxide synthase (eNOS), enhanced the expression of endothelin-1 and adhesion molecules (ICAM, E-selectin, and monocyte chemoattractant protein-1), and increased the adherence of monocytic THP-1 cells to HUVECs. Pretreatment with EGCG, however, exerted significant cytoprotective effects in all events. These data suggest that EGCG inhibits the oxLDL-induced LOX-1-mediated signaling pathway, at least in part, by inhibiting NADPH oxidase and consequent ROS-enhanced LOX-1 expression, which contributes to further ROS generation and the subsequent activation of NF-kappaB via the p38 MAPK pathway. Results from this study may provide insight into a possible molecular mechanism by which EGCG suppresses oxLDL-mediated vascular endothelial dysfunction.