Concentrations Of Epigallocatechin-3-gallate Research Articles

Antibacterial Activity of Epigallocatechin Gallate (EGCG) against Shigella flexneri.

Shigella flexneri (S. flexneri), a major intestinal pathogen, is a global public health concern. The biofilms formed by S. flexneri threaten environmental safety, since they could promote the danger of environmental contamination and strengthen the disease-causing properties of bacteria. Epigallocatechin gallate (EGCG) is an important catechin in tea, which has a high antibacterial activity. However, its antibacterial mechanism is still unclear. This research aims to quantify the antibacterial function and investigate the possible mechanism of EGCG inhibition of S. flexneri. The minimum inhibitory concentration (MIC) of EGCG against planktonic S. flexneri in the investigation was measured to be 400 μg/mL. Besides, SDS-PAGE and field emission scanning electron microscopy showed that EGCG interfered with protein synthesis and changed bacteria morphology. Through controlling the expression of the mdoH gene, EGCG was found to be able to prevent an S. flexneri biofilm extracellular polysaccharide from forming, according to experiments utilizing the real-time PCR test. Additional research revealed that EGCG might stimulate the response of S. flexneri to oxidative stress and prevent bacterial growth. These findings suggest that EGCG, a natural compound, may play a substantial role in S. flexneri growth inhibition.

Investigation of Phenolic Compounds and Antioxidant Activity of Sorbaria pallasii (Rosaceae) Microshoots Grown In Vitro.

Sorbaria pallasii is an endemic species of the Far East and Siberia and grows along the Goltsy altitudinal belt. Data on micropropagation and phytochemical characteristics of this plant are not available, probably because of the inaccessibility of the plant material. Morphogenesis initiation from flower buds of S. pallasii in vitro and micropropagation were performed here in the Murashige and Skoog medium supplemented with 5.0 µM 6-benzylaminopurine and 0.0-1.0 µM α-naphthylacetic acid; elongation was implemented in the same medium without the hormones. A well-growing sterile culture of S. pallasii was obtained; the number of microshoots per explant reached 5.7 ± 1.2. Phytochemical analyses of in vitro propagated S. pallasii detected 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in a water-ethanol extract from its microshoots and revealed phenolic compounds in it. The phenolic compounds that likely contribute to its biological activity are tannins (74.9 mg/g), phenolcarboxylic acids (30.8 mg/g), and catechins (13.3 mg/g). In the microshoot extract, high-performance liquid chromatography identified three catechins. Microshoots showed the highest concentration of (±)-catechin (3.03 mg/(g of absolutely dry mass; ADM)). Concentrations of epigallocatechin gallate (0.38 mg/(g of ADM)) and (-)-epicatechin (0.55 mg/(g of ADM)) were significantly lower. This study paves the way for further biotechnological and phytochemical research on S. pallasii.

Integrative analyses of transcriptome and metabolome reveal comprehensive mechanisms of Epigallocatechin-3-gallate (EGCG) biosynthesis in response to ecological factors in tea plant (Camellia sinensis)

Epigallocatechin-3-gallate (EGCG), a flavoured and healthy compounds in tea, is affected by the ecological factors. However, the biosynthetic mechanisms of EGCG in response to the ecological factors remian unclear. In this study, a response surface method with a Box-Behnken design was used to investigate the relationship between EGCG accumulation and ecological factors; further, integrative transcriptome and metabolome analyses were performed to explore the mechanism underlying EGCG biosynthesis in response to environmental factors. The optimal environmental conditions obtained for EGCG biosynthesis were as follows: 28℃, 70 % relative humidity of the substrate, and 280 µmol·m−2·s−1 light intensity; the EGCG content was increased by 86.83 % compared to the control (CK1). Meanwhile, the order of EGCG content in response to the interaction of ecological factors was as follows: interaction of temperature and light intensity > interaction of temperature and relative humidity of the substrate > interaction of light intensity and relative humidity of the substrate, indicating that temperature was the dominant ecological factors. EGCG biosynthesis in tea plants was found to be comprehensively regulated by a series of structural genes (CsANS, CsF3H, CsCHI, CsCHS, and CsaroDE), miRNAs (miR164, miR396d, miR5264, miR166a, miR171d, miR529, miR396a, miR169, miR7814, miR3444b, and miR5240), and transcription factors (MYB93, NAC2, NAC6, NAC43, WRK24, bHLH30, and WRK70); further, the metabolic flux was regulated and converted from phenolic acid to the flavonoid biosynthesis pathway based on accelerated consumption of phosphoenolpyruvic acid, d-erythrose-4-phosphate, and l-phenylalanine in response to ambient changes in temperature and light intensity. Overall, the results of this study reveal the effect of ecological factors on EGCG biosynthesis in tea plants, providing novel insights for improving tea quality.

Epigallocatechin-3-gallate enhances sterilization of irradiated whole bovine casein and protects alpha and beta caseins from gamma radiation: Depending on polyphenol/protein ratio

The increasing use of milk proteins in medicine requires developing effective processes for sterilizing milk formulations. It was found that epigallocatechin-3-gallate (EGCG) reduce bacterial flora in total casein, depending on the concentration of EGCG. Furthermore, the combination of EGCG and gamma radiation reduced the dose D10 to 0.88 kGy and 0.63 kGy with 250 and 500 μM EGCG, respectively, instead 2.01 kGy without EGCG. The effect of gamma radiation on alpha- and beta-casein in the absence and presence of epigallocatechin-3-gallate (EGCG) was also examined. Milk proteins in solution were exposed to different doses of gamma radiation with and without EGCG. Unirradiated and irradiated samples were analyzed by SDS-PAGE and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS). The results suggest that EGCG (10 μM) protects α- and β-casein from degradation and subsequent polymerization, possibly by scavenging oxygen and protein free radicals generated during irradiation. Although it was used a ratio of polyphenols to the protein higher for alpha-casein (1/5) than beta-casein (1/10), beta-casein was better protected with EGCG. According to previous studies, this result could be explained by differences in primary protein structure and its interaction with EGCG. The interaction of EGCG with casein is hydrophobic rather than hydrophilic, so the interaction with β-casein is more robust than with α-casein. In conclusion, the low EGCG concentrations enhance the sterilization of total casein by gamma radiation. It provided an excellent radioprotection of α- and β-casein, especially β-casein, against degradation and aggregation.

The WRKY Transcription Factor CsWRKY70 Regulates EGCG Biosynthesis by Affecting CsLAR and CsUGT84A Expressions in Tea Leaves (Camellia sinensis)

Epigallocatechin gallate (EGCG) is an important contributor to bitterness and astringency in summer tea leaves; however, the transcriptional regulatory mechanisms of EGCG biosynthesis remain unclear. In this study, EGCG content was significantly decreased after foliar spraying with nano-Se fertilizers in tea leaves. A WRKY transcription factor (TF), CsWRKY70, was found to be positively related to EGCG content. The open reading frame of CsWRKY70 was 891 bp encoding 296 amino acids. CsWRKY70 is localized to the nucleus and has transcriptional activation activity. The electrophoretic mobility shift assay indicated that CsWRKY70 can directly bind to the promoters of CsLAR and CsUGT84A containing W-box (5′-C/TTGACT/C-3′) sequences. Dual-luciferase reporter experiment verified that CsWRKY70 activated CsLAR and CsUGT84A expressions in tobacco leaves. In summary, these results demonstrated that CsWRKY70 may reduce EGCG biosynthesis by inhibiting the CsLAR and CsUGT84A expressions under nano-Se treatment. Our findings provide new insight into the regulatory mechanism of WRKY TFs involved in catechin biosynthesis and offer a theoretical basis for breeding low or high EGCG content tea cultivars.

Effect of EGCG Extracted from Green Tea against Largemouth Bass Virus Infection.

(1) Background: Largemouth bass virus (LMBV) is a major viral pathogen in largemouth bass (Micropterus salmoides) aquaculture that often causes high mortality and heavy economic losses, thus developing treatments to combat this pathogen is of great commercial importance. Green tea is a well-known medicinal plant that contains active ingredients with antiviral, antibacterial, and other biological activities. The goals of this study were to explore the effect and mechanism of green tea source compounds on LMBV and provide data to serve as the basis for the screening of targeted drugs in the future. In this study, we evaluated the effects of the main component of green tea, epigallocatechin-3-gallate (EGCG), against LMBV infection. (2) Methods: The safe working concentration of EGCG was identified by cell viability detection and light microscopy. The antiviral activity and mechanism of action of EGCG against LMBV infection were evaluated with light microscopy, an aptamer 6-carboxy-fluorescein-based fluorescent molecular probe, and reverse transcription quantitative PCR. (3) Results: The safe working concentration of EGCG was ≤10 μg/mL. EGCG showed significant anti-LMBV infection activity in a concentration-dependent manner, and it also destroyed the structure of virus particles. EGCG impacted the binding of virus particles to cell receptors and virus invasion into the host cells. Inhibitory effects of EGCG on LMBV particles, LMBV binding to the host-cell membrane, and LMBV invasion were 84.89%, 98.99%, and 95.23%, respectively. Meanwhile, the effects of EGCG subsequently were verified in vivo. The fatality rate of the LMBV + EGCG group was significantly lower than that of the LMBV group. (4) Conclusions: Our results suggest that EGCG has effective antiviral properties against LMBV and may be a candidate for the effective treatment and control of LMBV infections in largemouth bass aquaculture.

Effects of α-Tocopherol, β-Carotene and Epigallocatechin Gallate on the Oxidative Stability of Sunflower Oil.

Using sunflower oil as the oil matrix, the antioxidant effects and types of interactions of three natural components, α-tocopherol, β-carotene and epigallocatechin gallate (EGCG), were investigated and the kinetic model of oxidation reaction was established. The results showed that the ability of the three antioxidants to scavenge DPPH radicals was ranked as EGCG > β-carotene > α-tocopherol in the concentration range of 0~100 mg/kg. 15 samples were obtained by combining two of three natural components. When the concentration ratios of β-carotene and EGCG were 1:20 and 1:7.5, α-tocopherol and EGCG were 1:13.3, 1:6, and 1:2, and α-tocopherol and β-carotene were 1:0.2 and 1:0.05, the type of interaction was synergistic, while the rest of the samples showed antagonistic effects. The sample with a 1:13.3 concentration of α-tocopherol and EGCG showed the longest induction period, the lowest oxidation rate constant, the highest activation energy, the best oxidative stability, and the longest shelf life at different temperatures. This compounded natural antioxidant was the most favorable for the stability of sunflower oil. This provides some theoretical basis for the development and application of compounded natural antioxidants in vegetable oils.

Synergistic antimicrobial potential of EGCG and fosfomycin against biofilms associated with endodontic infections.

This study aimed to evaluate the cytotoxicity and synergistic effect of epigallocatechin gallate (EGCG) and fosfomycin (FOSFO) on biofilms of oral bacteria associated with endodontic infections. This study determined minimum inhibitory and bactericidal concentration (MIC/MBC) and fractionated inhibitory concentration (FIC) of EGCG and FOSFO against Enterococcus faecalis, Actinomyces israelii, Streptococcus mutans, and Fusobacterium nucleatum. Monospecies and multispecies biofilms with those bacteria formed in polystyrene microplates and in radicular dentin blocks of bovine teeth were treated with the compounds and control chlorhexidine (CHX) and evaluated by bacterial counts and microscopy analysis. Toxicity effect of the compounds was determined on fibroblasts culture by methyl tetrazolium assays. The combination of EGCG + FOSFO demonstrated synergism against all bacterial species, with an FIC index ranging from 0.35 to 0.5. At the MIC/FIC concentrations, EGCG, FOSFO, and EGCG+FOSFO were not toxic to fibroblasts. EGCG+FOSFO significantly reduced monospecies biofilms of E. faecalis and A. israelli, whereas S. mutans and F. nucleatum biofilms were eliminated by all compounds. Scanning electron microscopy of multispecies biofilms treated with EGCG, EGCG+FOSFO, and CHX at 100x MIC showed evident biofilm disorganization and substantial reduction of extracellular matrix. Confocal microscopy observed a significant reduction of multispecies biofilms formed in dentin tubules with 84.85%, 78.49%, and 50.6% of dead cells for EGCG+FOSFO, EGCG, and CHX at 100x MIC, respectively. EGCG and fosfomycin showed a synergistic effect against biofilms of oral pathogens related to root canal infections without causing cytotoxicity.

Effects of Epigallocatechin Gallate on the Cytotoxicity of Epirubicin-HCl in Lung Cancer Cells

Background: Studies have shown that epigallocatechin-3-gallate (EGCG), which is present in green tea at a higher rate than other components, has an additive or synergistic cytotoxic effect when applied with different anticancer drugs and reduces the side effects caused by anticancer drugs. It is known that the order of administration of drugs in combined applications also affects cytotoxicity. In this context, in our study, the most effective application sequence was determined by evaluating the cytotoxic responses of epirubicin-HCl and EGCG according to the different application order in A-549 cells (NSCLC). Methods: To demonstrate the apoptotic activity, we detected changes in mRNA ratios of Bax, a pro-apoptotic gene, and Bcl-2, an anti-apoptotic gene, (Bax/Bcl2), as well as changes in the activity of caspase 3/7 enzyme. To demonstrate the effect of oxidative stress generation, we investigated changes in glutathione peroxidase activity. Results: It was observed that the cell viability of A-549 cells exposed to different concentrations of epirubicin-HCl and EGCG for 48 h decreased depending on the concentration increase. According to the results of cell viability in cells to which epirubicin-HCl (<IC50) and EGCG (<IC50) were treated with together, and the combination index (CI) value calculations, the most effective combination concentrations were determined to be IC20 Epirubicin-HCl and IC10 EGCG. LDH activities were found higher in epirubicin-HCl + EGCG treatment than epirubicin-HCl alone treatment compared to control groups. Treatment of epirubicin-HCl with EGCG was found to be more effective in increasing glutathione peroxidase activity than epirubicin-HCl alone. Both of epirubicin-HCl alone and combination traetments caused increase in Bax/Bcl-2 ratio in A-549 cells. Conclusion: Combination therapy of epirubicin-HCl with EGCG may be a light in the future for lung cancer patients who are tried to be treated with conventional chemotherapy drugs but cannot achieve the desired success.

"Efficacy of cytotoxic effect of green tea catechins on the human periodontal fibroblasts and human dental pulp fibroblasts -An in vitro study".

Inflammation of tooth-supporting tissue and the pulp tissue is followed by wound healing and regeneration process that involves the specific type of connective tissue cells, the fibroblasts. During periodontitis and pulpitis, the inflammation of the tissue causes damage to the fibroblasts. These fibroblasts secrete collagen proteins and maintain the structural framework; along with this the inflammatory process moves toward healing where in the specific cells such as the fibroblast cells play important roles. Green tea catechins epigallocatechin-3-gallate (EGCG) being one of the major catechins is known to have multiple beneficial effects on human fibroblasts. To assess the in vitro cytotoxicity of green tea catechins on the human periodontal ligament (PDL) fibroblasts and human dental pulp fibroblasts. Human PDL fibroblasts (hPDLFs) and human dental pulp fibroblasts were isolated from the two extracted premolar teeth that were indicated for orthodontic treatment. The fibroblasts were then seeded in 96 well tissue culture plate for cell viability study. EGCG was used at different concentration to treat the cells. After 48 h; (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) (MTT) assay was performed to determine the cell viability. The vitality of hPDLFs and human dental pulp fibroblasts was found to be inversely proportional to EGCG concentrations. hPDLFs have shown 37% proliferation at lowest concentration of EGCG used and human dental pulp fibroblasts have shown 99% viability at lowest concentration of EGCG used.

Increased expression of androgen receptor and PSA genes in LNCaP (prostate cancer) cell line due to high concentrations of EGCG, an active ingredient in green tea.

Androgen receptor (AR) play a key role in the onset and progression of prostate cancer. Epigallocatechin-3-gallate (EGCG) is a polyphenolic compound and the active ingredient in green tea, which is involved in modulating gene expression through epigenetic alterations. Previous studies have shown that EGCG at low concentrations reduces the expression of AR and prostate-specific antigen (PSA) in the LNCaP cell line of prostate cancer. In this study, the effect of higher EGCG concentrations on AR and PSA expression in LNCaP prostate cancer cell line was investigated. In this study, LNCaP prostate cancer cell line was used and after MTT test, concentrations of 40, 60 and 80μg/mL EGCG were used for treatment. Then, the expression of AR and PSA genes was evaluated by RT-PCR. AR protein expression was also assessed by Western blotting. The present study showed that treatment of LNCaPs cells by EGCG reduces cell proliferation. The IC50 value was 42.7μg/mL under experimental conditions. It was also observed that EGCG at concentrations of 40 and 80μg/mL increased the expression of AR and PSA (p<0.05). The present study showed that the effect of EGCG on AR expression was different at different concentrations, so that unlike previous studies, higher concentrations of EGCG (80 and 40μg/mL) increased AR and PSA expression. It seems that due to the toxic effects of EGCG in high concentrations on cancer cells and the possibility of its effect on normal cells, more caution should be exercised in its use.

Physicochemical Properties and Oxidative Stability of an Emulsion Prepared from (-)-Epigallocatechin-3-Gallate Modified Chicken Wooden Breast Myofibrillar Protein.

The deterioration of wooden breast myofibrillar protein (WBMP) causes a decline in its processing performance, and the protein becomes easier to oxidize. Previous studies have revealed that the use of (-)-epigallocatechin-3-gallate (EGCG) may improve the physicochemical properties and oxidative stability of proteins in aqueous solutions. The effects of varying concentrations (0.01%, 0.02%, 0.03%, and 0.04% w/v) of EGCG on the physicochemical properties of a WBMP emulsion (1.2% WBMP/10% oil) and the inhibition of lipid and protein oxidation were studied. The results revealed that a moderate dose of EGCG (0.03%) could significantly (p &lt; 0.05) improve the emulsion activity index (4.66 ± 0.41 m2/g) and emulsion stability index (91.95 ± 4.23%), as well as reduce the particle size of the WBMP emulsion. According to the micrographs and cream index, 0.03% EGCG retarded the phase separation by stopping the aggregation of droplets and proteins, thus significantly improving the stability of WBMP emulsions. During storage at 50 °C for 96 h, 0.03% EGCG inhibited lipid oxidation (lipid hydroperoxide and 2-thiobarbituric acid-reactive substance formation) and protein oxidation (carbonyl formation and sulfhydryl loss). In contrast, lower and higher EGCG concentrations (0.01%, 0.02%, and 0.04%) demonstrated shortcomings (such as weak antioxidant capacity or protein over-aggregation) in improving the quality and oxidation stability of the emulsion. In conclusion, a moderate dose of EGCG (0.03%) can be used to improve the quality and shelf life of WBMP emulsions.

The Loading of Epigallocatechin Gallate on Bovine Serum Albumin and Pullulan-Based Nanoparticles as Effective Antioxidant.

Due to its poor stability and rapid metabolism, the biological activity and absorption of epigallocatechin gallate (EGCG) is limited. In this work, EGCG-loaded bovine serum albumin (BSA)/pullulan (PUL) nanoparticles (BPENs) were successfully fabricated via self-assembly. This assembly was driven by hydrogen bonding, which provided the desired EGCG loading efficiency, high stability, and a strong antioxidant capacity. The encapsulation efficiency of the BPENs was above 99.0%. BPENs have high antioxidant activity in vitro, and, in this study, their antioxidant capacity increased with an increase in the EGCG concentration. The in vitro release assays showed that the BPENs were released continuously over 6 h. The Fourier transform infrared spectra (FTIR) analysis indicated the presence of hydrogen bonding, hydrophobic interactions, and electrostatic interactions, which were the driving forces for the formation of the EGCG carrier nanoparticles. Furthermore, the transmission electron microscope (TEM) images demonstrated that the BSA/PUL-based nanoparticles (BPNs) and BPENs both exhibited regular spherical particles. In conclusion, BPENs are good delivery carriers for enhancing the stability and antioxidant activity of EGCG.

Microbial metabolic transformation and antioxidant activity evaluation of polyphenols in kombucha

Kombucha is a kind of traditional fermented sugared tea rich in polyphenols. Although the health effects of tea polyphenols (TPPs) have been extensively studied, the biotransformation of the TPPs during kombucha fermentation was not fully elucidated. In this study, the polyphenol transformation capacity of microbial strains and the synthetic microbial communities during the tea broth fermentation were investigated. Firstly, six microbial species demonstrated different polyphenol transformation abilities: Acetobacter pasteurianus, Zygosaccharomyces bailii and Debaryomyce hansenii could increase the contents of epigallocatechin gallate (EGCG), the most abundant components of TPPs. Z. bailii and Acetobacter xylinum could enhance the concentration of TPPs with low molecular weight. Then, four synthetic microbial communities (SMC) consisting of different species were constructed to ferment the black tea broth. When different strains coexisted, their interaction could further enhance kombucha's phenols transformation and antioxidant activity. Specifically, the SMC, constructed by Z. bailii, L. plantarum and D. hansenii, could enhance the EGCG content significantly in tea broth and the total phenols and flavonoid contents. Meanwhile, the antioxidant activities of kombucha fermented by this SMC were found to be relatively high among different fermented tea broth groups. Besides, it is demonstrated that A. pasteurianus was a strong competitor in the tea broth environment. This bacterium could decrease the number of viable yeast cells by producing more acid. This study demonstrated that the construction of suitable synthetic microbial communities would help reveal the phenolic metabolic characteristics of complex microbial communities and obtain customizable phenolic combinations for kombucha products.

Epigallocatechin-3-gallate protects porcine oocytes against post-ovulatory aging through inhibition of oxidative stress.

Increased levels of oxidative stress are major factors that drive the process of post-ovulatory oocyte aging. Epigallocatechin-3-gallate (EGCG), which accounts for up to 50% of the catechins, possesses versatile biological functions, including preventing or treating diabetes, cancer, and heart diseases. The aim of this study was to explore whether EGCG can delay porcine oocyte aging by preventing oxidative stress. Metaphase II (MII) oocytes were cultured for 48 h with different concentrations of EGCG (0-100 μM) in vitro as a post-ovulatory aging model. An optimal concentration of 5 μM EGCG maintained oocyte morphology and developmental competence during aging. The oocytes were randomly divided into five groups: fresh, 24 h control, 24 h EGCG, 48 h control, and 48 h EGCG. The results suggest that EGCG significantly prevents aging-induced oxidative stress, glutathione (GSH) reduction, apoptosis, and autophagy. Moreover, mitochondria DNA copy number was decreased, and the number of active mitochondria and adenosine triphosphate (ATP) levels significantly increased by supplementation with EGCG. Thus, EGCG has a preventive role against aging in porcine post-ovulatory oocytes due to its ability to inhibit oxidative stress and promote mitochondrial biogenesis.

Epigallocatechin-3-Gallate Decreases Plasma and Urinary Levels of p-Cresol by Modulating Gut Microbiota in Mice.

p-Cresol (PC), a gut bacterial product of tyrosine catabolism, is recognized as a uremic toxin that has negative biological effects. Lowering the plasma PC level by manipulating the gut bacterial composition represents a promising therapeutic strategy in chronic kidney disease. This study was conducted to reveal whether epigallocatechin-3-gallate (EGCG) decreases plasma PC levels by limiting its bacterial production in a mouse model. The PC concentration in the samples was measured by high-performance liquid chromatography (HPLC) after treatments with sulfatase and β-glucuronidase. The results showed that the addition of EGCG to the diet decreased the plasma and urinary concentrations of PC in a dose-dependent manner, with a statistically significant difference between the control group and the 0.2% EGCG group. However, once EGCG was enzymatically hydrolyzed to epigallocatechin (EGC) and gallic acid, such effects were lost almost completely. The addition of 0.2% EGCG in the diet was accompanied by a decreased abundance of Firmicutes at the phylum level and Clostridiales at the order level, which constitute a large part of PC produced from tyrosine. In conclusion, EGCG, not EGC, reduced plasma and urinary concentrations of PC in mice by suppressing its bacterial production with accompanying alteration of the relative abundance of PC producers.

Use of Physiologically Based Kinetic Modeling-Based Reverse Dosimetry to Predict In Vivo Nrf2 Activation by EGCG and Its Colonic Metabolites in Humans.

(-)-Epigallocatechin gallate (EGCG) is prone to microbial metabolism when reaching the colon. This study aimed to develop a human physiologically based kinetic (PBK) model for EGCG, with sub-models for its colonic metabolites gallic acid and pyrogallol. Results show that the developed PBK model could adequately predict in vivo time-dependent blood concentrations of EGCG after either the single or repeated oral administration of EGCG under both fasting and non-fasting conditions. The predicted in vivo blood Cmax of EGCG indicates that the Nrf2 activation is limited, while concentrations of its metabolites in the intestinal tract may reach levels that are higher than that of EGCG and also high enough to activate Nrf2 gene transcription. Taken together, combining in vitro data with a human PBK model allowed the prediction of a dose-response curve for EGCG-induced Nrf2-mediated gene expression in humans and provided insights into the contribution of gut microbial metabolites to this effect.

Enzymatic synthesis of sodium caseinate-EGCG-carboxymethyl chitosan ternary film: Structure, physical properties, antioxidant and antibacterial properties

Proteins and polysaccharides have been frequently used in recent years to prepare environment-friendly packaging materials. However, films based on proteins or polysaccharides alone often have poor performance as packaging, so they need to be combined to improve properties. In this work, we applied enzyme technology to prepare sodium caseinate (SC)-carboxymethyl chitosan (CMC) films, incorporating epigallocatechin gallate (EGCG) as bridging molecules and antibacterial agents. SC-EGCG-CMC ternary conjugate was firstly synthesized by tyrosinase (Tyr), and the composite films were then prepared with the aid of glycerol. Under tyrosinase catalytic conditions, EGCG could cross-link with SC and CMC covalently. The effects of different concentrations of EGCG and tyrosinase on mechanical properties, water vapor permeability, antibacterial properties and free radical scavenging ability were studied. The crosslinking degree and mechanical properties were improved with the increase of EGCG and tyrosinase content. The film showed good antibacterial activity against Gram-positive bacteria. In addition, the antibacterial activity and free radical scavenging ability increased with the increase of EGCG concentration. This work provides an efficient enzymatic method to prepare films with good strength and antibacterial properties, which can be used to improve the storage quality of foods.

Effect of epigallocatechin gallate on the fermentative and physicochemical properties of fermented milk.

Yogurt, a traditional fermented dairy product, is made with a starter that contains Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. The aim of this study was to investigate the effects of different concentrations of epigallocatechin gallate (EGCG; 0, 0.5, 1.0, 3.0, and 5.0 mg/mL) on the growth, metabolism, and acid production of lactic acid bacteria, as well as the texture, stability, and antioxidant activity of fermented milk (yogurt). The results showed that a low concentration of EGCG had no significant effect on the acid production capacity of the starter or on the water-holding capacity of the yogurt but did increase its viscosity. A high concentration (5.0 mg/mL) of EGCG delayed the acid production rate of the starter and decreased the water-holding capacity, but significantly increased the antioxidant activity of yogurt. The addition of EGCG significantly increased the hardness of yogurt. Therefore, EGCG can improve the texture of fermented milk and enhance its antioxidant activity and stability, thus improving the overall quality of yogurt.

The combination of EGCG with warfarin reduces deep vein thrombosis in rabbits through modulating HIF-1α and VEGF via the PI3K/AKT and ERK1/2 signaling pathways.

Deep venous thrombosis (DVT) poses a major challenge to public health worldwide. Endothelial cell injury evokes inflammatory and oxidative responses that contribute to thrombus formation. Tea polyphenol (TP) in the form of epigallocatechin-3-gallate (EGCG) has anti-inflammatory and oxidative effect that may ameliorate DVT. However, the precise mechanism remains incompletely understood. The current study was designed to investigate the anti-DVT mechanism of EGCG in combination with warfarin (an oral anticoagulant). Rabbits were randomly divided into five groups. A DVT model of rats was established through ligation of the inferior vena cava (IVC) and left common iliac vein, and the animals were orally administered with EGCG, warfarin, or vehicle for seven days. In vitro studies included pretreatment of human umbilical vein endothelial cells (HUVECs) with different concentrations of EGCG for 2 h before exposure to hydrogen peroxide. Thrombus weight and length were examined. Histopathological changes were observed by hematoxylin-eosin staining. Blood samples were collected for detecting coagulation function, including thrombin and prothrombin times, activated partial thromboplastin time, and fibrinogen levels. Protein expression in thrombosed IVCs and HUVECs was evaluated by Western blot, immunohistochemical analysis, and/or immunofluorescence staining. RT-qPCR was used to determine the levels of AGTR-1 and VEGF mRNA in IVCs and HUVECs. The viability of HUVECs was examined by CCK-8 assay. Flow cytometry was performed to detect cell apoptosis and ROS generation was assessed by 2',7'-dichlorofluorescein diacetate reagent. In vitro and invivo studies showed that EGCG combined with warfarin significantly reduced thrombus weight and length, and apoptosis in HUVECs. Our findings indicated that the combination of EGCG and warfarin protects HUVECs from oxidative stress and prevents apoptosis. However, HIF-1α silencing weakened these effects, which indicated that HIF-1α may participate in DVT. Furthermore, HIF-1α silencing significantly up-regulated cell apoptosis and ROS generation, and enhanced VEGF expression and the activation of the PI3K/AKT and ERK1/2 signaling pathways. In conclusion, our results indicate that EGCG combined with warfarin modifies HIF-1α and VEGF to prevent DVT in rabbits through anti-inflammation via the PI3K/AKT and ERK1/2 signaling pathways.