ovalbumin and epigallocatechin-gallate

Topics: Animals; Cell Degranulation; Cytokines; Disease Models, Animal; Female; Hypersensitivity; Interleukin-13; Interleukin-4; Mast Cells; Mice; Mice, Inbred BALB C; Ovalbumin; Phosphatidylinositol 3-Kinases

The influence of ultrasound-assisted free radical modification on the structure and functional properties of ovalbumin-epigallocatechin gallate (OVA-EGCG) conjugates was investigated by experimental measurements and computer simulations. Compared with the traditional free radical condition, the ultrasonic-assisted processing significantly increased the conjugating efficiency of OVA and EGCG and shortened the conjugating from 24 h to 1 h without affecting the equivalent amount of EGCG conjugating. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis and multi-spectroscopy analysis (Fourier transform infrared spectroscopy, intrinsic fluorescence spectroscopy, and UV spectroscopy) indicated that the covalent conjugates could be formed between OVA and EGCG. And modification in the conformation of OVA was induced by EGCG. Furthermore, molecular docking results demonstrated the possession of high-affinity EGCG binding location on OVA, supporting and clarifying the experimental results. In addition, the functional properties of OVA including emulsification (emulsifying activity and emulsion stability) and antioxidant properties (DPPH scavenging capacity and ABTS scavenging capacity) were significantly improved after conjugation with EGCG, especially in ultrasound-assisted conditions. Overall, OVA-EGCG conjugates produced by ultrasound-assisted free radical treatment could be applied as a potential emulsifier and antioxidant, thereby expanding the application of OVA as a dual-functional ingredient.

Topics: Antioxidants; Free Radicals; Molecular Docking Simulation; Ovalbumin; Spectroscopy, Fourier Transform Infrared

The mechanism of epigallocatechin gallate (EGCG)-modified ovalbumin gel (EMOG) was investigated. Results indicated that, with the increase of EGCG concentration from 0% to 0.05%, the opacity, hardness, and cohesiveness of EMOG increased significantly from 0.058 to 0.133, 321.0 g to 377.6 g, and 0.879 to 0.951, respectively, while the soluble protein, surface hydrophobicity, and free sulfhydryl decreased significantly by 41.74%, 28.26%, and 39.36%, respectively. Moreover, EGCG promoted the formation of dense and stable microstructures of EMOG, changed the expansion rate, and improved the stability of EMOG. Moreover, the results of silico simulation showed that EGCG would insert into ovalbumin and interact with the amino acids through van der Waals force and hydrogen bonds, leading to a compact and stable protein structure. In this paper, the mechanism of modification of ovalbumin by EGCG was elucidated at the macro and micro levels, providing insights into the action of polyphenols and proteins.

Topics: Catechin; Computer Simulation; Hydrogen; Ovalbumin; Protein Aggregates

Asthma is a chronic disease associated with hyperresponsiveness, obstruction and remodeling of the airways. Epithelial-mesenchymal transition (EMT) has an important role in these alterations and may account for the accumulation of subepithelial mesenchymal cells, thus contributing to airway hyperresponsiveness and remodeling. Epigallo-catechin‑3‑gallate (EGCG), which is a type of polyphenol, is the most potent ingredient in green tea, and exhibits antibacterial, antiviral, antioxidative, anticancer and chemopreventive activities. Recently, numerous studies have investigated the protective effects of EGCG against asthma and other lung diseases. In the present study, the role of EGCG in ovalbumin (OVA)‑challenged asthmatic mice was determined. In addition, the inhibitory effects of EGCG against transforming growth factor (TGF)‑β1‑induced EMT and migration of 16HBE cells, and the underlying mechanisms of the phosphatidylinositol 3‑kinase/protein kinase B (PI3K/Akt) signaling pathway, were investigated by immunofluorescence, Transwell, wound healing assay and western blot analysis, respectively. The results indicated that EGCG may suppress inflammation and inflammatory cell infiltration into the lungs of OVA‑challenged asthmatic mice, and may also inhibit EMT via the PI3K/Akt signaling pathway through upregulating the expression of phosphatase and tensin homolog (PTEN) in vivo and in vitro. The present study also revealed the anti‑migratory effects of EGCG in TGF‑β1‑induced 16HBE cells, thus suggesting it may reduce airway remodeling. The present study provides a novel insight into understanding the protective effects of EGCG on airway remodeling in asthma, and indicates that EGCG may be useful as an adjuvant therapy for bronchial asthma.

Topics: Airway Remodeling; Animals; Asthma; Catechin; Disease Models, Animal; Epithelial-Mesenchymal Transition; Humans; Inflammation; Mice; Oncogene Protein v-akt; Ovalbumin; Phosphatidylinositol 3-Kinases; PTEN Phosphohydrolase; Signal Transduction; Tea

Currently, a variety of studies have demonstrated that green tea has anti-allergic properties, and the major polyphenolic compound, epigallocatechin gallate (EGCG), plays a significant role. Some research indicates that EGCG reduces the production and expression of allergy-related substances. Therefore, EGCG has a potential effect of reducing allergic rhinitis (AR). In this study, the effect of EGCG on allergic rhinitis in an ovalbumin (OVA)-induced mouse model was investigated. After administration of EGCG, the number of sneezes and the occurrence of nasal rubbing were significantly decreased, the concentrations of immunoglobulin E (IgE) and histamine were suppressed in AR mouse serum, the levels of interleukin (IL)-1β, IL-4, and IL-6 were reduced in AR mice nasal lavage fluid (NLF), and the nasal mucosa mRNA and protein expression of cyclooxygenase 2 (COX-2), IL-1β, IL-4, and IL-6 were inhibited. The data indicate that EGCG has a beneficial effect of reducing allergic rhinitis.

Topics: Allergens; Animals; Anti-Inflammatory Agents; Catechin; Cyclooxygenase 2; Cytokines; Disease Models, Animal; Female; Histamine; Humans; Immunoglobulin E; Inflammation Mediators; Mice; Mice, Inbred BALB C; Ovalbumin; Rhinitis, Allergic; Sneezing; Tea

Nanoparticles have the potential to increase bioavailability of nutraceutical compounds such as (-)-epigallocatechin gallate (EGCG). Ovalbumin was conjugated with dextran using the Maillard reaction. The resultant ovalbumin-dextran (O-D) conjugates were self-assembled with EGCG to form EGCG O-D conjugate nanoparticles at pH 5.2 after heating at 80 °C for 60 min. Ovalbumin in EGCG O-D conjugate nanoparticles was further cross-linked by glutaraldehyde for 24 h at room temperature. EGCG O-D conjugate nanoparticles and cross-linked EGCG O-D conjugate nanoparticles in aqueous suspension had particle sizes of 285 and 339 nm, respectively, and showed a spherical morphology. The loading efficiencies of EGCG in these two nanoparticles were 23.4 and 30.0%, whereas the loading capacities were 19.6 and 20.9%, respectively. These nanoparticles showed positive zeta-potentials in a pH range from 2.5 to 4.0 but had negative charges at pH ≥5.0. EGCG O-D conjugate nanoparticles maintained a particle size of 183-349 nm in simulated gastric fluid (SGF) and 188-291 nm in simulated intestinal fluid (SIF) at 37 °C for 2 h, whereas cross-linked nanoparticles had particle sizes of 294-527 nm in SGF and 206-300 nm in SIF. Limited release of EGCG was observed in both nanoparticle systems in simulated gastric and intestinal fluids without and with digestive enzymes. EGCG O-D conjugate nanoparticles significantly enhanced the apparent permeability coefficient (Papp) of EGCG on Caco-2 monolayers compared with EGCG solution, suggesting that these nanoparticles may improve the absorption of EGCG.

Topics: Caco-2 Cells; Catechin; Dextrans; Digestion; Drug Stability; Gastrointestinal Tract; Glutaral; Humans; Hydrogen-Ion Concentration; Intestinal Absorption; Intestinal Mucosa; Maillard Reaction; Nanoparticles; Ovalbumin; Particle Size

Polyphenols, the potent plant secondary metabolites, have beneficial effects on human health, but the mechanism(s) by which these effects are exerted is not well understood. Here, we present the detailed analysis of the interactions between the major green tea catechin, epigallo-catechin 3-gallate (EGCG), and the major dietary protein and allergen, ovalbumin (OVA). We show that EGCG binds to the pocket that partly overlaps with the previously identified IgE-binding region in OVA, and that this interaction induces structural changes in the allergen. Moreover, our ex vivo studies reveal that OVA binds IgE and stimulates degranulation of basophils, and that its uptake by monocytes proceeds at a slower rate in the presence of EGCG. This study provides further evidence in support of the proposed mechanism by which EGCG interactions with the food allergens contribute to its diverse biological activities and may impair antigen uptake by antigen-presenting cells.

Topics: Allergens; Antigen-Presenting Cells; Basophils; Catechin; Circular Dichroism; Egg White; Electrophoresis, Polyacrylamide Gel; Food Hypersensitivity; Humans; Immunoglobulin E; Monocytes; Ovalbumin; Polyphenols; Protein Binding; Protein Conformation; Spectrometry, Fluorescence; Tea

Green tea is a widely consumed beverage known for its beneficial anti-inflammatory, anti-oxidative, anti-mutagenic, anti-carcinogenic, and cardioprotective properties. Here, we administered epigallocatechin gallate fraction of green tea extract (EGTE) to mice for 6 weeks and examined the effects on the innate and adaptive immune responses by measuring phagocytic and natural killer (NK) cell activity, as well as antigen-specific proliferation, cytolysis, cytokine secretion, and antibody production. Our data show that EGTE administration increased NK cell cytolysis and peritoneal cell phagocytosis, as well as splenocyte proliferation and secretion of IL-2 and IFN-γ. Of note, EGTE treatment decreased the production antigen-specific IgE via increased the proportion of CD4+ CD25+ regulatory T lymphocytes in the spleen, suggesting that EGTE may play a role in regulating the allergic response.

Topics: Adaptive Immunity; Animals; B-Lymphocytes; Catechin; Cell Proliferation; Female; Immunity, Innate; Killer Cells, Natural; Mice; Mice, Inbred BALB C; Ovalbumin; Phagocytes; Phagocytosis; Plant Extracts; T-Lymphocytes, Regulatory; Tea

The preventive effects of C-2 epimeric isomers of (-)-epigallocatechin-3-O-gallate (EGCG) and the O-methylated derivative, (-)-epigallocatechin-3-O-(3-O-methyl)gallate (EGCG3''Me), against ovalbumin-induced type I allergy in male mice were investigated. EGCG and EGCG3''Me exhibited strong antiallergic effects by oral administration at doses of 25 and 50 mg/kg body weight. The antiallergic effects of their C-2 epimers, (-)-gallocatechin-3-O-gallate and (-)-gallocatechin-3-O-(3-O-methyl)gallate (GCG3''Me), on mouse type I allergy were almost equivalent to and/or as strong as those of the corresponding original catechins, respectively. Oral administration of these compounds at a dose of 50 mg/kg body weight tended to suppress the increases in interleukin-4 levels in the abdominal walls of allergic mice and immunoglobulin E levels in the serum of allergic mice. In particular, the administration of GCG3''Me exhibited significant effects on the production and/or release of these parameters stimulating type 2 T helper cells and mast cells in the type I allergic process. These results indicated that C-2 epimerization of tea catechins, which are produced during heat processing at high temperatures, would not be disadvantageous for preventive effects on type I allergy.

Topics: Abdominal Wall; Allergens; Animals; Anti-Allergic Agents; Catechin; Dose-Response Relationship, Immunologic; Hypersensitivity, Immediate; Immunoglobulin E; Interleukin-10; Interleukin-4; Isomerism; Male; Mice; Ovalbumin; Tea

In this study, we have evaluated the effects of the polyphenol epigallocatechin-3-gallate (EGCG), an antioxidant molecule that also enhances constitutive nitric-oxide synthase (NOS) activity, on antigen-induced asthma-like reaction in sensitized guinea pigs. For comparison, we used epicatechin, which shares antioxidant but not NOS-modulating properties with EGCG. Ovalbumin-sensitized guinea pigs placed in a respiratory chamber were challenged with ovalbumin. EGCG (25 mg/kg b.wt.) or epicatechin (25 mg/kg b.wt.) was given i.p. 20 min before ovalbumin challenge. We analyzed latency time for the onset of respiratory abnormalities, cough severity, duration of dyspnea, lung tissue histopathology, mast cell activation (by granule release), leukocyte/eosinophilic infiltration (by major basic protein and myeloperoxidase), oxygen free radical-mediated injury (by nitrotyrosine and 8-hydroxy-2-deoxyguanosine and superoxide dismutase), NOS activity, and bronchial inflammatory response [by tumor necrosis factor-alpha in bronchoalveolar lavage (BAL)]. In the sensitized animals, severe respiratory abnormalities appeared soon after the antigen challenge, accompanied by bronchoconstriction, alveolar inflation, and a marked increase in the assayed parameters of inflammatory cell recruitment, free radical lung injury, and release of proinflammatory molecules in BAL fluid. This was associated with marked depression of constitutive NOS activity. Pretreatment with EGCG, but not epicatechin, significantly reduced all the above parameters and sustained endothelial-type NOS activity. These findings provide evidence that EGCG, probably by modulating NOS activity, can counteract allergic asthma-like reaction in sensitized guinea pigs and suggest its possible future use for the treatment of asthma.

Topics: Allergens; Animals; Anti-Asthmatic Agents; Asthma; Bronchoalveolar Lavage Fluid; Catechin; Disease Models, Animal; Guinea Pigs; Lung; Male; Nitric Oxide Synthase; Ovalbumin