Green Tea Flavonoids Research Articles

Binding of green tea epigallocatechin gallate to the arginine kinase active site from the brown recluse spider (Loxosceles laeta): A potential synergist to chemical pesticides

Loxosceles spp. spiders can cause serious public health issues. Chemical control is commonly used, leading to health and environmental problems. Identifying molecular targets and using them with natural compounds can help develop safer and eco-friendlier biopesticides. We studied the kinetics and predicted structural characteristics of arginine kinase (EC 2.7.3.3) from Loxosceles laeta (LlAK), a key enzyme in the energy metabolism of these organisms. Additionally, we explored (−)-epigallocatechin gallate (EGCG), a green tea flavonoid, as a potential lead compound for the LlAK active site through fluorescence and in silico analysis, such as molecular docking and molecular dynamics (MD) simulation and MM/PBSA analyses. The results indicate that LlAK is a highly efficient enzyme (KmArg 0.14 mM, KmATP 0.98 mM, kcat 93 s−1, kcat/KmArg 630 s−1 mM−1, kcat/KmATP 94 s−1 mM−1), which correlates with its structure similarity to others AKs (such as Litopenaeus vannamei, Polybetes pythagoricus, and Rhipicephalus sanguineus) and might be related to its important function in the spider's energetic metabolism. Furthermore, the MD and MM/PBSA analysis suggests that EGCG interacted with LlAK, specifically at ATP/ADP binding site (RMSD <1 nm) and its interaction is energetically favored for its binding stability (−40 to −15 kcal/mol). Moreover, these results are supported by fluorescence quenching analysis (Kd 58.3 μM and Ka 1.71 × 104 M-1). In this context, LlAK is a promising target for the chemical control of L. laeta, and EGCG could be used in combination with conventional pesticides to manage the population of Loxosceles species in urban areas.

The Green Tea Polyphenol Epigallocatechin-Gallate (EGCG) Interferes with Microcin E492 Amyloid Formation

Microcin E492 (MccE492) is an antimicrobial peptide and proposed virulence factor produced by some Klebsiella pneumoniae strains, which, under certain conditions, form amyloid fibers, leading to the loss of its antibacterial activity. Although this protein has been characterized as a model functional amyloid, the secondary structure transitions behind its formation, and the possible effect of molecules that inhibit this process, have not been investigated. In this study, we examined the ability of the green tea flavonoid epigallocatechin gallate (EGCG) to interfere with MccE492 amyloid formation. Aggregation kinetics followed by thioflavin T binding were used to monitor amyloid formation in the presence or absence of EGCG. Additionally, synchrotron radiation circular dichroism (SRCD) and transmission electron microscopy (TEM) were used to study the secondary structure, thermal stability, and morphology of microcin E492 fibers. Our results showed that EGCG significantly inhibited the formation of the MccE492 amyloid, resulting in mainly amorphous aggregates and small oligomers. However, these aggregates retained part of the β-sheet SRCD signal and a high resistance to heat denaturation, suggesting that the aggregation process is sequestered or deviated at some stage but not completely prevented. Thus, EGCG is an interesting inhibitor of the amyloid formation of MccE492 and other bacterial amyloids.

Oxidative stress, hormones, and effects of natural antioxidants on intestinal inflammation in inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a chronic, relapsing gastrointestinal (GI) disorder characterized by intestinal inflammation. The etiology of IBD is multifactorial and results from a complex interplay between mucosal immunity, environmental factors, and host genetics. Future therapeutics for GI disorders, including IBD, that are driven by oxidative stress require a greater understanding of the cellular and molecular mechanisms mediated by reactive oxygen species (ROS). In the GI tract, oxidative stressors include infections and pro-inflammatory responses, which boost ROS generation by promoting the production of pro-inflammatory cytokines. Nuclear factor kappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2) represent two important signaling pathways in intestinal immune cells that regulate numerous physiological processes, including anti-inflammatory and antioxidant activities. Natural antioxidant compounds exhibit ROS scavenging and increase antioxidant defense capacity to inhibit pro-oxidative enzymes, which may be useful in IBD treatment. In this review, we discuss various polyphenolic substances (such as resveratrol, curcumin, quercetin, green tea flavonoids, caffeic acid phenethyl ester, luteolin, xanthohumol, genistein, alpinetin, proanthocyanidins, anthocyanins, silymarin), phenolic compounds including thymol, alkaloids such as berberine, storage polysaccharides such as tamarind xyloglucan, and other phytochemicals represented by isothiocyanate sulforaphane and food/spices (such as ginger, flaxseed oil), as well as antioxidant hormones like melatonin that target cellular signaling pathways to reduce intestinal inflammation occurring with IBD.

Study of Serial Exposures of an Astringent Green Tea Flavonoid Extract with Oral Cell-Based Models.

It is well known that repeated exposure to phenolic compounds (PCs) raises astringency perception. However, the link between this increase and the oral cavity's interactions with salivary proteins (SPs) and other oral constituents is unknown. To delve deeper into this connection, a flavonoid-rich green tea extract was tested in a series of exposures to two oral cell-based models using a tongue cell line (HSC3) and a buccal mucosa cell line (TR146). Serial exposures show cumulative PC binding to all oral models at all concentrations of the green tea extract; however, the contribution for the first and second exposures varies. The tongue mucosal pellicle (HSC3-Mu-SP) may contribute more to first-stage astringency (retaining 0.15 ± 0.01 mg mL-1 PCs at the first exposure), whereas the buccal mucosal pellicle (TR146-Mu-SP) retained significantly less (0.08 ± 0.02 mg mL-1). Additionally, increased salivary volume (SV+), which simulates the stimulation of salivary flow brought by a food stimulus, significantly enhances PC binding, particularly for TR146 cells: TR46-Mu-SP_SV+ bound significantly higher total PC concentration (0.17 ± 0.02 mg mL-1) than the model without increased salivary volume TR146-Mu-SP_SV- (0.09 ± 0.03 mg mL-1). This could be associated with a higher contribution of these oral cells for astringency perception during repeated exposures. Furthermore, PCs adsorbed in the first exposure to cell monolayer models (+TR146 and +HSC3) change the profile of PCs bound to these models in the second exposure. Regarding the structure binding activity, PCs with a total higher number of hydroxyl groups were more bound by the models containing SP. Regarding the SP, basic proline-rich proteins (bPRPs) may be involved in the increased perception of astringency upon repeated exposures. The extent of bPRP precipitation by PCs in mucosal pellicle models for both cell lines (HSC3 and TR146) in the second exposure (76 ± 13 and 83 ± 6%, respectively) was significantly higher than in the first one (25 ± 14 and 5 ± 6%, respectively).

A Mechanocomposite Based on Biogenic Silica and Green Tea Flavonoids Modulates Adaptability of Strawberry Microclones to In Vitro and Ex Vitro Conditions

A Mechanocomposite Based on Biogenic Silica and Green Tea Flavonoids Modulates Adaptability of Strawberry Microclones to In Vitro and Ex Vitro Conditions

The influence of green tea extract on nintedanib’s bioavailability in patients with pulmonary fibrosis

Nintedanib is an oral small-molecule kinase inhibitor and first-line treatment for idiopathic pulmonary fibrosis. Nintedanib is a substrate of the drug efflux transporter ABCB1. Green tea flavonoids --especially epigallocatechin gallate (EGCG)-- are potent ABCB1 modulators. We investigated if concomitant administration of green tea extract (GTE) could result in a clinically relevant herb-drug interaction.Patients were randomized between A-B and B-A, with A being nintedanib alone and B nintedanib with GTE. Both periods lasted 7 days, in which nintedanib was administered twice daily directly after a meal. In period B, patients additionally received capsules with GTE (500 mg BID, >60% EGCG). Pharmacokinetic sampling for 12 h was performed at day 7 of each period. Primary endpoint was change in geometric mean for the area under the curve (AUC0–12 h). A linear mixed model was used to analyse AUCs and maximal concentration (Cmax).In 26 included patients, the nintedanib AUC0–12 h was 21% lower (95% CI −29% to −12%; P < 0.001) in period B (with GTE) compared to period A. Cmax did not differ significantly between periods; − 14% (95% CI −29% to +4%; P = 0.12). The detrimental effect was predominant in patients with the ABCB1 3435 C>T wild type variant. No differences in toxicities were observed.Exposure to nintedanib decreased with 21% when administered 60 min after GTC for only 7 days. This is a statistically significant interaction which could potentially impair treatment efficacy. Before patients and physicians should definitely be warned to avoid this combination, prospective clinical validation of an exposure-response relationship is necessary.

Comparing the application of conventional and supercritical CO 2 extracts of green tea; storage stability and sensory acceptance of coriander sauce

Green tea extract is anticipated to improve storage stability of coriander sauce and hence employed in the development of sauces; S1 carrying 3% of conventional extract (epigallocatechin gallate; EGCG 65.88 ± 2.38 mg/g D.W.) and S2 containing 2.56% of supercritical CO2 extract (EGCG 77.23 ± 2.86 mg/g D.W.) then compared against control (S0). During storage (4°C), numerous parameters were studied at Days 1, 7, 14, 21, and 28. Maximum polyphenols (mg GAE/100 ml) were observed in S2 (224.40 ± 5.82) followed by S1 (208.31 ± 5.03) and S0 (50.11 ± 1.71) and similar trend was noted for antioxidant assays. Further, tea extracts prominently reduced synersis in sauces, i.e., 42.79%–47.31% in relevance to control and no abnormality was reported in color traits. Likewise, deviations in physicochemical aspects of sauce during storage were considerably (p < .05) delayed by either extract. Acceptance index of the treated sauces was higher, i.e., 77.52% ± 2.77% (S1) and 78.91% ± 2.83% (S2) than control (75.66% ± 2.64%). Practical applications Green tea extracts, predominantly supercritical CO2 extract, have proven its preservative role in coriander sauce by delaying anomalous changes that may arise during storage without imparting any off-sensory characteristics in the final product. Besides, inclusion of green tea in coriander sauce compliments each other as green tea extract enhances the functionality and quality of coriander sauce, whereas acidic environment of the sauce facilitates in stabilizing green tea polyphenols and flavonoids. Based on health benefits and improved storage stability of the resultant product, the relevant stakeholders should need to bring this innovative idea to reality.

Study of flavonoids and phenolic acids in green tea leaves

The aim of work is study qualitative composition and quantitative content of flavonoids and phenolic acids in green tea leaves. Material and methods. The object of the study was green tea leaves, which were collected in Anhui Province, China. The analysis of 60 % ethanolic extract from green tea leaves was performed by high-performance liquid chromatography using a Prominence LC-20 Shimadzu chromatographic system (Japan) with an SPD-20AV spectrophotometric detector, an Agilent Technologies Microsorb-MV-150 column (reversed-phase, C18 modified silica gel, length – 250 mm, diameter – 4.6 mm, particles size – 5 μm). Identification of substances in the extract was carried out by comparing the retention time and the spectral characteristics of the test substances with the same characteristics of the reference standards. Results. 13 compounds were identified and determined by high-performance liquid chromatography. Among flavonoid aglycones quantitatively dominated by quercetin (0.35 %), in the case of flavonoid glycosides, it was luteolin-6-C-glycoside (1.30 %) and among phenolic acids, it was gallic acid (5.21 %). Conclusions. The qualitative composition, quantitative content of flavonoids and phenolic acids in the green tea leaves were determined by high-performance liquid chromatography. According to HPLC, the content of flavonoids in green tea leaves was higher than the content of phenolic acids.

Cerebral Cortex Apoptosis in Early Aged Hypertension: Effects of Epigallocatechin-3-Gallate.

This study aimed to investigate cerebral cortex apoptosis on the early aged hypertension and the effects of green tea flavonoid epigallocatechin-3-gallate (EGCG). Twenty-four rats were divided into three groups: a control Wistar-Kyoto group (WKY, n = 8), a spontaneously early aged hypertensive group (SHR, n = 8), and an early aged hypertension with EGCG treatment group (SHR-EGCG, n = 8; daily oral EGCG 200 mg/kg—94%, 12 weeks). At 48 weeks old, blood pressures (BPs) were evaluated and cerebral cortexes were isolated for TUNEL assay and Western blotting. Systolic, diastolic, and mean blood pressure levels in the SHR-EGCG were reduced compared to the SHR. The percentage of neural cell deaths, the levels of cytosolic Endonuclease G, cytosolic AIF (Caspase-independent apoptotic pathway), Fas, Fas Ligand, FADD, Caspase-8 (Fas-mediated apoptotic pathway), t-Bid, Bax/Bcl-2, Bak/Bcl-xL, cytosolic Cytochrome C, Apaf-1, Caspase-9 (Mitochondrial-mediated apoptotic pathway), and Caspase-3 (Fas-mediated and Mitochondria-mediated apoptotic pathways) were increased in the SHR relative to WKY and reduced in SHR-EGCG relative to SHR. In contrast, the levels of Bcl-2, Bcl-xL, p-Bad, 14-3-3, Bcl-2/Bax, Bcl-xL/Bak, and p-Bad/Bad (Bcl-2 family-related pro-survival pathway), as well as Sirt1, p-PI3K/PI3K and p-AKT/AKT (Sirt1/PI3K/AKT-related pro-survival pathway), were reduced in SHR relative WKY and enhanced in SHR-EGCG relative to SHR. In conclusion, green tea flavonoid epigallocatechin-3-gallate (EGCG) might prevent neural apoptotic pathways and activate neural survival pathways, providing therapeutic effects on early aged hypertension-induced neural apoptosis.

Systemic epigallocatechin gallate protects against retinal degeneration and hepatic oxidative stress in the P23H-1 rat

Retinitis pigmentosa (RP) is a group of inherited retinal disorders that lead to photoreceptor loss. RP has been reported to be related to oxidative stress, autophagy, and inflammation. (-)-Epigallocatechin gallate (EGCG), the most abundant catechin-based flavonoid in green tea leaves, has significant antioxidant, anti-carcinogenic, antimicrobial, and neuroprotective properties. EGCG, given its low molecular weight and hydrophilic properties, can cross the blood-retinal barrier and is able to reach different ocular tissues such as the lens, cornea, and retina. EGCG has been shown to provide retinal protection against ischemia; sodium nitroprusside-, N-methyl-D-aspartate-, lipopolysaccharide-, light-, sodium iodate-, or H2O2-induced damage and diabetic retinopathy. This suggests that systemic EGCG administration has the potential to protect against retinal degenerative or neurodegenerative diseases such as RP. The aim of this work was to investigate whether EGCG can protect against RP progression in the animal P23H line 1, the model of RP. Albino P23H rats were crossed with pigmented Long Evans rats to produce offspring exhibiting the clinical features of RP. Pigmented P23H rats were treated via intraperitoneal injection with saline or EGCG at a dose of 25 mg/kg every week from P100 to P160 and then compared to wild-type Long Evans rats. Rats treated with EGCG showed better visual and retinal electrical function with increased contrast sensitivity and b-wave values compared with those observed in P23H rats treated with vehicle. EGCG reduced lipid peroxidation and increased total antioxidant capacity and catalase and superoxide dismutase activities. No differences were observed in visual acuity, nitrate levels, nitrite levels or glutathione S-transferase activity. In conclusion, EGCG not only reduced the loss of visual function in P23H rats but also improved the levels of antioxidant enzymes and reduced oxidative damage. This study was approved by the Institutional Animal Care and Use Committee (CEICA) from the University of Zaragoza under project license PI12/14 on July 11, 2014.

Evaluation of Green Tea Effect on Oral Bacteria, Streptococcus Mutans

Tea is a gift of China to the world. It is a popular beverage consumed by almost every person globally, after water. Green tea has not gone under oxidation process and found beneficial for human consumption because of its medicinal properties and presence of some nutrients and minerals required by human beings for a healthy life. Molecular component of green tea (Polyphenols, catechins, flavonoids and minerals) makes it suitable in ailments and some microbial infections. Oral cavity has the second largest and diverse microbiota after gut, as numerous microorganisms such as bacteria, fungi and viruses exist in the mouth. Streptococcus mutans is facultative, anaerobic oral bacteria mainly responsible for tooth decay was selected for the present study because dental plaque and caries are common infections found in population. For experimental purpose 30 healthy individuals were randomly selected from the college campus (MIET, Meerut). Saliva of each individual was taken twice i.e. before and after green tea consumption. For identification and confirmation of S. mutans, biochemical tests have been done. The effect of green tea was observed by the growth and count of S. mutans on common (nutrient agar media) and special media (Mitis Salivary agar media). Plates were showing less count after green tea consumption as compared to the plates before consumption of green tea. On the basis of the results, it can be concluded that Green tea is the natural preventive and curative agents and is good to consume once in a day to reduce the count of Streptococcus mutans in mouth to maintain oral health.

Green tea catechins and intracellular calcium dynamics in prostate cancer cells

Perturbations of internal Ca²⁺ ([Ca²⁺]_i) homeostasis play a key role in several pathologies and in neoplastic transformation, where deregulated cell proliferation, together with the suppression of apoptosis, provides the condition for abnormal tissue growth and invasion. Green tea catechins have been shown to affect cancer development by interference with basic cellular functions, most of which are mediated by [Ca²⁺]_i. Prostate cancer (PCa) is one of the most common malignancy in men in Western countries and the androgen-independent carcinoma is a lethal form for which there is still no effective therapy. Different evidences suggested that consumption of green tea may have beneficial effects against PCa. We have previously described how the main green tea flavonoid, (−)-epigallocatechin-3-gallate (EGCG), inhibited proliferation and induced dose-dependent peaks of [Ca²⁺]_i in metastatic androgen-insensitive DU145 and PC3 PCa cells, by a mechanism that combined Ca²⁺ entry and Ca²⁺-induced Ca²⁺ release. In the present study, we studied the effect of green tea extract (GTE) on the same cell lines. Proliferation, measured by MTT assay, was inhibited by GTE with IC₅₀ close to 60 µg/ml, a value that is higher than that expected by EGCG effect alone. [Ca²⁺]_i, measured in real time by the fluorescent dye Fura-2, was transiently increased by GTE by a mechanism that resembled that described for EGCG, but was largely independent of external Ca²⁺. These observations suggested that other components, acting in synergy with EGCG, were involved in GTE effect, and confirmed the view that the alleged health benefits of green tea for PCa prevention may be related to [Ca²⁺]_i deregulation in malignant cells. These results may be significant to understand the functional mechanisms by which flavonoids exert their beneficial or toxic actions.

Inhibition of starch digestion by flavonoids: Role of flavonoid-amylase binding kinetics

In this study, kinetics of binding between α-amylase and green tea flavonoids were investigated by fluorescence quenching (FQ). Their effect on α-amylase inhibition was evaluated. Whereas epicatechin (EC) and epigallocatechin (EGC) exhibited slow binding kinetics (in the order of minutes), epicatechin gallate (ECG) and epigallocatechin gallate (ECGC) exhibited very rapid binding (in the order of seconds) with Human Salivary α-amylase (HSA) and Porcine Pancreatic α-amylase (PPA). EGCG reached maximum inhibition of HSA and PPA with short incubation time whereas maximum inhibition of HSA and PPA by EC was reached only after 45 to 60 min of incubation. Similar results with ECG and EGC, but not in line with FQ kinetics, highlighted possible interferences of starch-flavonoid interaction in the binding and inhibition process. These results suggest that incubation times of enzymes and flavonoids shall be evaluated prior to enzyme inhibition testing in order to ensure consistent and reliable results.

Identification of Pathways of A498 Human Kidney Carcinoma Cell Death under the Action of Gratiola officinalis L. Extract and Green Tea Flavonoids Using Fluorescence Imaging Techniques

Using fluorescence methods for visualization of human tumor cell apoptosis and necrosis in vitro, the antitumor effects of flavonoid-containing Gratiola officinalis L. and green tea extracts at ultralow concentrations on A498 human kidney carcinoma cells after 24 and 48 h were compared. Fluorescent dyes (propidium iodide and acridine orange) were used in the “living and dead” test, which made it possible to identify the total number of cells that died by necrosis and apoptosis, as well as cells in which apoptosis has started and apoptotic bodies or pycnosis of the nucleus were detected. Gratiola officinalis L. extract had the most pronounced cytostatic activity 48 h after exposure; the number of cells per field of view decreased by a factor of 1.5 compared with the control. Green tea extract at a concentration of 0.0288 mg/mL had the most pronounced cytotoxic activity; its manifestation was growing 48 h after exposure. Gratiola officinalis L. extract exhibited cytotoxic activity at lower concentrations (0.0036 mg/mL).

Effect of a High Flavonoid Supplement on Intestinal Inflammation, Short Chain Fatty Acids, and the Gut Microbiome

Abstract Objectives Endurance exercise is a known cause of intestinal inflammation. Recent studies suggest that dietary flavonoids may protect the gut from chronic low-grade inflammation and have other effects at the gastrointestinal barrier. As a result, the purpose of this study was to determine the effects of a high flavonoid supplement containing blueberry, green tea, and cocoa on gut health. We investigated changes in intestinal inflammation, fecal short chain fatty acids (SCFA), and the gut microbiome in a randomized clinical trial. Methods In a double-blind, crossover design, 12 recreationally-active cyclists (VO2 max: 43.2 + 5.9 ml/kg/min) completed two 15-day supplementation periods with either a high flavonoid supplement or placebo. The high flavonoid beverage (HFB, 490 mg total flavonoids) and macronutrient-matched low flavonoid control (LFB, 5 mg flavonoids) were consumed once daily, two hours prior to training. Stool samples were collected once during days 9–11 of each intervention to determine microbiome composition and SCFA (acetic, propionic, butyric, isobutyric, valeric, isovaleric, and caproic acid). Fecal calprotectin was used as a marker of intestinal inflammation. Results Food frequency questionnaires estimated that the participants’ average weekly consumption of total flavonoids was 634.7 ± 194.6 mg, with the highest subgroups being flavan-3-ols, flavonols, and anthocyanidins (296.3 ± 169.3, 136.5 ± 21.9, 109.6 ± 35.4 mg, respectively). There was no significant difference in fecal calprotectin on the HFB versus LFB (P &amp;gt; 0.05). Average fecal calprotectin were low (HFB: 12.9 ± 1.2, LFB: 12.9 ± 0.9 ug/g stool), suggesting that subjects had low overall gut inflammation. There were no significant differences in individual and total SCFA (P &amp;gt; 0.05). The total SCFA on the HFB treatment was 115.1 ± 11.3 mM/g vs. 107.9 ± 9.7 mM/g on the LFB. Furthermore, there were no differences in any measures alpha or beta diversity as a result of the dietary intervention (P &amp;gt; 0.05). Conclusions Fifteen-day consumption of a blend of blueberry, cocoa, and green tea flavonoids did not significantly affect gut inflammation, SCFA content, and alpha or beta diversity of the gut microbiome. Funding Sources Build Dairy.

Effect of silicon chelates from plant raw materials on some physiological parameters in strawberry under in vitro conditions

For the first time, the effect mechanocomposite based on biogenic silica and green tea flavonoids (MC) on reduction of oxidative stress in microshoots of strawberry plantlets (cv. “Solnechnaya polyanka”) during in vitro multiplication, shoot elongation and rooting stages were established. Compared with the plantlets cultured in MC-free media, the ones cultured in media supplemented with MC showed increased key antioxidant enzyme activities (superoxide dismutase – SOD, peroxidase – POD, catalase – CAT). SOD activity increased from 1.1 to 1.4 times at 2.5 and 5.0 mg L-1 MC, POD activity – from 1.8 to 3.8 times at 5.0 and 10.0 mg L-1 MC, and CAT activity – from 1.1 to 1.4 times at 5.0 mg L-1 MC depending on the stage of micropropagation. The high antioxidant enzyme activities correlated with the decrease of H2O2 content (up to 1.7 times compared with the control). The revealed changes in the physiological status of strawberry plantlets in the presence of MC contribute to the further successful acclimatization of regenerants to ex vitro conditions. Thus, these results have demonstrated the potential of “green chemistry” for the production of healthy plant material of strawberry cultivars.

Stability and Fermentability of Green Tea Flavonols in In-Vitro-Simulated Gastrointestinal Digestion and Human Fecal Fermentation.

Flavonols, the second most abundant flavonoids in green tea, exist mainly in the form of glycosides. Flavonols are known to have a variety of beneficial health effects; however, limited information is available on their fate in the digestive system. We investigated the digestive stability of flavonol aglycones and glycosides from green tea under simulated digestion and anaerobic human fecal fermentation. Green tea fractions rich in flavonol glycosides and aglycones, termed flavonol-glycoside-rich fraction (FLG) and flavonol-aglycone-rich fraction (FLA) hereafter, were obtained after treatment with cellulase and tannase, respectively. Kaempferol and its glycosides were found to be more stable in simulated gastric and intestinal fluids than the derivatives of quercetin and myricetin. Anaerobic human fecal fermentation with FLG and FLA increased the populations of Lactobacilli spp. and Bifidobacteria spp. and generated various organic acids, such as acetate, butyrate, propionate, and lactate, among which butyrate was produced in the highest amount. Our findings indicate that some stable polyphenols have higher bioaccessibilities in the gastrointestinal tract and that their health-modulating effects result from their interactions with microbes in the gut.

The Protective Effects of Green Tea Catechins in the Management of Neurodegenerative Diseases: A Review.

The therapeutic strategies to manage neurodegenerative diseases remain limited and it is necessary to discover new agents for their prevention and control. Oxidative stress and inflammation play a main role in the pathogenesis of neurodegenerative diseases. The aim of this study is to review the effects of green tea catechins against the Neurodegenerative Diseases. In this study, we extensively reviewed all articles on the terms of Green tea, catechins, CNS disorders, and different diseases in PubMed, Science Direct, Scopus, and Google Scholar databases between the years 1990 and 2017. The present study found that catechins, the major flavonoids in green tea, are powerful antioxidants and radical scavengers which possess the potential roles in the management of neurodegenerative diseases. Catechins modulate the cellular and molecular mechanisms through the inflammation-related NF-κB and the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways. The findings of the present review shows catechins could be effective against neurodegenerative diseases due to their antioxidation and anti-inflammation effects and the involved biochemical pathways including Nrf2 and NF-kB signaling pathways.

Red wine and green tea flavonoids are cis-allosteric activators and competitive inhibitors of glucose transporter 1 (GLUT1)-mediated sugar uptake

The antioxidant- and flavonoid-rich contents of red wine and green tea are reported to offer protection against cancer, cardiovascular disease, and diabetes. Some studies, however, show that flavonoids inhibit GLUT1-mediated, facilitative glucose transport, raising the possibility that their interaction with GLUT1 and subsequent downstream effects on carbohydrate metabolism may also impact health. The present study explores the structure-function relationships of flavonoid-GLUT1 interactions. We find that low concentrations of flavonoids act as cis-allosteric activators of sugar uptake, whereas higher concentrations competitively inhibit sugar uptake and noncompetitively inhibit sugar exit. Studies with heterologously expressed human GLUT1, -3, or -4 reveal that quercetin-GLUT1 and -GLUT4 interactions are stronger than quercetin-GLUT3 interactions, that epicatechin gallate (ECG) is more selective for GLUT1, and that epigallocatechin gallate (EGCG) is less GLUT isoform-selective. Docking studies suggest that only one flavonoid can bind to GLUT1 at any instant, but sugar transport and ligand-binding studies indicate that human erythrocyte GLUT1 can bind at least two flavonoid molecules simultaneously. Quercetin and EGCG are each characterized by positive, cooperative binding, whereas ECG shows negative cooperative binding. These findings support recent studies suggesting that GLUT1 forms an oligomeric complex of interacting, allosteric, alternating access transporters. We discuss how modulation of facilitative glucose transporters could contribute to the protective actions of the flavonoids against diabetes and Alzheimer's disease.

(-)-Epigallocatechin gallate but not chlorogenic acid suppresses EGF-stimulated migration of osteoblasts via attenuation of p38 MAPK activity.

Phenolic compounds provide health benefits in humans. A previous study by our group has indicated that the epidermal growth factor (EGF)-induced migration of osteoblast-like MC3T3-E1 cells is mediated by the phosphorylation of p44/p42 mitogen-activated protein (MAPK), p38 MAPK, stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK) and Akt, and that resveratrol, a major polyphenol in grape skin, suppresses the EGF-induced migration by attenuating Akt and SAPK/JNK activation. In the present study, the effects of chlorogenic acid, a major phenolic acid in coffee, and (−)-epigallocatechin gallate (EGCG), a major flavonoid in green tea, on the EGF-induced migration of MC3T3-E1 cells were investigated. EGCG significantly reduced the EGF-induced migration as evaluated by a Transwell migration assay and by a wound healing assay. However, chlorogenic acid failed to affect the EGF-induced migration. The phosphorylation of p38 MAPK induced by EGF was significantly suppressed by EGCG; however, the EGF-induced phosphorylation of p44/p42 MAP kinase, SAPK/JNK or Akt was not affected by EGCG. These results suggest that EGCG, but not chlorogenic acid, suppresses EGF-induced osteoblast migration through inhibiting p38 MAPK activation.