The inhibition of pectin oligosaccharides on degranulation of RBL-2H3 cells from apple pectin with high hydrostatic pressure assisted enzyme treatment

Exploration of digestion-resistant immunodominant epitopes in shrimp (Penaeus vannamei) allergens

The digestion products of Penaeus vannamei still had sensitizing and eliciting capacity; however, the underlying mechanism has not been identified. This study analyzed the structural changes of shrimp proteins during digestion, predicted the linearmimotopepeptides and first validated the allergenicity of immunodominantepitopes with binding ability. The results showed that the shrimp proteins were gradually degraded into small peptides during digestion, which might lead to the destruction of linear epitopes. However, these peptides carried IgE epitopes that still trigger allergic reactions. Eighteen digestion-resistant epitopes were predicted by multiple immunoinformatics tools and digestomics. Five epitopes contained more critical amino acids and had strong molecular docking (P1: DSGVGIYAPDAEA, P2: EGELKGTYYPLTGM, P3: GRQGDPHGKFDLPPGV, P4: IFAWPHKDNNGIE, P5: KSTESSVTVPDVPSIHD), and these epitopes were identified as novel IgE binding immunodominantepitopes in Penaeus vannamei. These findings provide novel insight into allergenic epitopes, which might serve as key targets for reducing the allergenicity in shrimp.

Marine-Derived Alternariol Monomethyl Ether Alleviates Ovalbumin-Induced Food Allergy by Suppressing MAPK and NF-κB Signaling Pathways of Mast Cells

The prevalence of food allergies has grown dramatically over the past decade. Recently, studies have shown the potential of marine substances to alleviate food allergies. We utilized a rat basophilic leukemia (RBL)-2H3 model to evaluate the antiallergic effects of alternariol monomethyl ether (AME) extracted from marine fungi Alternaria sp. Our results showed that AME attenuated food allergy symptoms in mice and reduced histamine release in serum. The population of mast cells in the spleen and mesenteric lymph nodes was considerably reduced. Moreover, in vitro assays also revealed that AME inhibited the release of β-hexosaminidase and histamine. Transcriptomic analysis uncovered that AME regulated gene expression associated with mast cells. Additionally, Western blotting demonstrated that AME suppressed mast cell activation by modulating MAPK and NF-κB signaling pathways. Taken together, these findings provide a theoretical basis for the potential antiallergic use of marine-derived compounds in the development of functional foods.

Sea Buckthorn Flavonoid Extracted by High Hydrostatic Pressure Inhibited IgE-Stimulated Mast Cell Activation through the Mitogen-Activated Protein Kinase Signaling Pathway

Sea buckthorn (Hippophaë rhamnoides L.), as one of the Elaeagnaceae family, has the significant function of anti-tumor, anti-inflammation, anti-oxidation, and other physiological activities. High hydrostatic pressure (HHP) extraction has the advantages of being easy and efficient, while maintaining biological activity. In this study, sea buckthorn flavonoid (SBF) was extracted with HHP and purified sea buckthorn flavonoid (PSBF) was isolated by AB-8 macroporous resin column. HPLC analysis was used to quantified them. In addition, the effect of anti-allergy in RBL-2H3 cells by SBF, PSBF, and their flavonoid compounds was evaluated. The results demonstrate the conditions for obtaining the maximum flavonoid amount of SBF: 415 MPa for 10 min, 72% ethanol concentration, and a liquid to solid ratio of 40 mL/g, which increased the purity from 1.46% to 13.26%. Both SBF and PSBF included rutin, quercitrin, quercetin, isorhamnetin, and kaempferol. In addition, quercitrin, kaempferol, and SBF could regulate Th1/Th2 cytokine balance. Moreover, extracellular Ca2+ influx was reduced by quercitrin and PSBF. Furthermore, rutin, quercetin, iso-rhamnetin, and SBF could also inhibit P-p38 and P-JNK expression, thereby suppressing the phosphorylation of the MAPK signaling pathways. Overall, SBF is effective for relieving food allergy and might be a promising anti-allergic therapeutic agent.

Inhibitory effect of rosmarinic acid on IgE-trigged mast cell degranulation in vitro and in vivo

BACKGROUND

Rosmarinic acid (RA), a polyphenol from edible-medical Lamiaceae herbs, is known to possess a variety of pharmacological activity, like anti-inflammatory, hepatoprotective and immunoregulation activities.

METHODS AND RESULTS

Hereon, we investigated the anti-allergic activity of RA on immunoglobulin E (IgE)-mediated anaphylaxis responses in rat basophilic leukemia (RBL)-2H3 mast cell. RA hindered the morphological changes of IgE-induced degranulated RBL-2H3 cells. The release of two key biomarkers (β-hexosaminidase (β-HEX) and histamine) of IgE-induced degranulated mast cells was also remarkably down-regulated by RA intervention in a dose dependent manner. Moreover, RA inhibited IgE-induced ROS overproduction and flux of intracellular Ca2+ in IgE-mediated degranulated mast cells. The q-PCR analysis showed that the expressions of genes (COX 2, PGD 2, LTC 4, HDC, Nrf2, HO-1 and NQO1) involved in MAPK and oxidative stress signaling pathways were significantly regulated by RA intervention. Moreover, the degranulation inhibitory effect of rosmarinic acid was investigated on the anti-DNP IgE/DNP-HSA induced passive cutaneous anaphylaxis (PCA) mice model in vivo. It showed that RA significantly inhibited the PCA reaction and allergic edema of ears in anti-DNP IgE/DNP-HSA stimulated mice.

CONCLUSION

These findings suggest that RA has the potential to be used as a therapeutic candidate for allergic diseases by inhibiting mast cell degranulation. This indicates a possible role for RA in managing allergic reactions and related conditions.

Modification methods, biological activities and applications of pectin: A review

Pectin is a complex and functionally rich natural plant polysaccharide that is widely used in food, medical, and cosmetic industries. It can be modified to improve its properties and expand its applications. Modification methods for natural pectin can be divided into physical, chemical, enzymatic, and compound methods. Different modification methods can result in modified pectins (MPs) exhibiting different physicochemical properties and biological activities. The objectives of this paper were to review the various pectin modification methods explored over the last decade, compare their differences, summarize the impact of different modification methods on the biological activity and physicochemical properties of pectin, and describe the applications of MPs in food and pharmaceutical fields. Finally, suggestions and perspectives for the development of MPs are discussed. This review offers a theoretical reference for the rational and efficient processing of pectin and the expansion of its applications.

Modulation of soy protein immunoreactivity by different matrix structures of lactic acid bacterium-induced soy protein gels: Epitope destruction during in vitro gastroduodenal digestion and absorption

Soy allergy is a common health problem. Food structure may change the gastroduodenal digestion and absorption of soy proteins, thus leading to the modulation of the immunoreactivity of soy proteins. In this study, lactic acid bacterium (LAB)-fermented soy protein isolates (FSPIs) were prepared at four concentrations (0.2 %-5.0 %, w/v) to present various matrix structures (nongel, NG; weak gel, WG; medium gel, MG; and firm gel, FG) and subjected to in vitro dynamic gastroduodenal digestion model. The results of sandwich enzyme-linked immunosorbent and human serum IgE binding capacity assays demonstrated that FSPI gels, especially the FSPI-MG/WG digestates obtained at the early and medium stages of duodenal digestion (D-5 and D-30), possessed greater potency in immunoreactivity reduction than FSPI-NG and reduced to 1.9 %-68.3 %. The transepithelial transport study revealed that the immunoreactivity of FSPI-MG/WG D-5 and D-30 digestates decreased through the stimulation of interferon-γ production and the induction of dominant Th1/Th2 differentiation. Peptidomics and bioinformatics analyses illustrated that compared with FSPI-NG, the FSPI-gel structure promoted the epitope degradation of the major allergens glycinin G2/G5, β-conglycinin α/β subunit, P34, lectin, trypsin inhibitor, and basic 7S globulin. Spatial structure analysis showed that FSPI-gel elicited an overall promotion in the degradation of allergen epitopes located in interior and exterior regions and was dominated by α-helix and β-sheet secondary structures, whereas FSPI-MG/WG promoted the degradation of epitopes located in the interior region of glycinin/β-conglycinin and exterior region of P34/basic 7S globulin. This study suggested that the FSPI-gel structure is a promising food matrix for decreasing the allergenic potential of allergenic epitopes during gastroduodenal digestion and provided basic information on the production of hypoallergenic soy products.

Effects of Lactobacillus fermentation on Eucheuma spinosum polysaccharides: Characterization and mast cell membrane stabilizing activity

Eucheuma polysaccharides have varieties of biological activities. However, it is accompanied by problems like large molecular weight, high viscosity, and low utilization. Here, we first prepared fermented Eucheuma spinosum polysaccharides (F-ESP) by Lactobacillus fermentation, compared with low-temperature freeze-thaw ESP (L-ESP) prepared by the freeze-thaw method, explored the composition and structural characteristics of F-ESP and L-ESP, and evaluation of the ability of different samples to inhibit mast cell degranulation using classical mast cell model. Then, the activity of L-ESP and F-ESP in vivo was preliminarily evaluated using a passive cutaneous anaphylaxis model. Two kinds of F-ESP named F1-ESP-3 and F2-ESP-3 were obtained by fermentation of Eucheuma spinosum with the selected strains of Lactobacillus.sakei subsp.sakei and Lactobacillus.rhamnosus. Compared with the purified component L-ESP-3, the monosaccharide composition of F1-ESP-3 contains more glucuronic acid, the molecular weight reduced from >600 kDa (L-ESP-3) to 28.30 kDa (F1-ESP-3) and 33.58 kDa (F2-ESP-3), F1-ESP-3 has higher solubility and lower apparent viscosity. Fermentation did not destroy the functional groups and structure of ESP. Moreover, F1-ESP-3 significantly inhibited RBL-2H3 cell degranulation by reducing depolymerization of F-actin and Ca²⁺ influx. F1-ESP-3 reduced the symptoms of mast cell-mediated passive cutaneous anaphylaxis, indicating that F1-ESP-3 may have better anti-allergic activity in vivo.

The Preparation and Potential Bioactivities of Modified Pectins: A Review

Pectins are complex polysaccharides that are widely found in plant cells and have a variety of bioactivities. However, the high molecular weights (M_w) and complex structures of natural pectins mean that they are difficult for organisms to absorb and utilize, limiting their beneficial effects. The modification of pectins is considered to be an effective method for improving the structural characteristics and promoting the bioactivities of pectins, and even adding new bioactivities to natural pectins. This article reviews the modification methods, including chemical, physical, and enzymatic methods, for natural pectins from the perspective of their basic information, influencing factors, and product identification. Furthermore, the changes caused by modifications to the bioactivities of pectins are elucidated, including their anti-coagulant, anti-oxidant, anti-tumor, immunomodulatory, anti-inflammatory, hypoglycemic, and anti-bacterial activities and the ability to regulate the intestinal environment. Finally, suggestions and perspectives regarding the development of pectin modification are provided.

Extraction and characterization of a pectin from sea buckthorn peel

Sea buckthorn peel is the by-product of the sea buckthorn processing, which contains many bioactive compounds. In this paper, sea buckthorn high methoxyl pectin (SBHMP) was obtained, with a yield of 8% and a light-colored. The SBHMP was a high methoxyl with a degree of esterification of 57.75% and uronic acid content of 65.35%. The structural and morphological characterization of SBHMP were analyzed by high-performance liquid chromatography, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Results showed that SBHMP presented a sheet and layered stacked morphological, and was mainly composed of galacturonic acid, arabinose, galactose, rhamnose, and mannose, which indicated that SBHMP mainly consisted of homogalacturonan (HG) and rhamnogalacturonan-I (RG-I) type pectin polysaccharides. In addition, SBHMP also presented significant gel, thickening, and emulsifying properties. The results exhibited that SBHMP could form jelly-like gels under acid and high sucrose conditions, presenting a shear-thinning behavior and increasing apparent viscosity with the enhancement of pectin and sucrose contents. Besides, SBHMP could form oil-in-water emulsions with pectin concentrations of 1.0–3.0%. When the SBHMP concentrations were 2.0 and 3.0%, the emulsions were stable during 7 days of storage. Findings in this paper demonstrated the potential of SBHMP to be a food thickener and emulsifier and support the in-depth utilization of sea buckthorn by-products.

Purified Saponins in Momordica charantia Treated with High Hydrostatic Pressure and Ionic Liquid-Based Aqueous Biphasic Systems

Momordica charantia L. (Cucurbitaceae) is rich in saponins, which have multiple biological effects. In this study, the total saponins of M. charantia were extracted by high hydrostatic pressure (HHP) technology. The optimal extraction process was determined (ethanol concentration 68%, pressure-holding time 8 min, ratio of material to solvent 1:35 and pressure 510 MPa), and the extraction amount of saponins reached 127.890 mg/g. On this basis, an ionic liquid-based aqueous biphasic system was constructed to purify the total saponins. Under the optimized conditions, the purity of M. charantia saponins was 76.06%. Liquid chromatography–mass spectrometry (LC/MS) was used to characterize the saponins in the purified extract of M. charantia. It was found that there were four kinds of saponins in the extract of M. charantia: kuguaglycoside A, momordicoside L, kuguacin B and kuguacin J, providing a basis for the study of the biological activity of saponins.

Role of the dietary components in food allergy: A comprehensive review

Currently, the increasing incidence of food allergy is considered a major public health and food safety concern. Importantly, food-induced anaphylaxis is an acute, life-threatening, systemic reaction with varied clinical presentations and severity that results from the release of mediators from mast cells and basophils. Many factors are blamed for the increasing incidence of food allergy, including hygiene, microbiota (composition and diversity), inopportune complementary foods (a high-fat diet), and increasing processed food consumption. Studies have shown that different food components, including lipids, sugars, polyphenols, and vitamins, can modify the immunostimulating properties of allergenic proteins and change their bioavailability. Understanding the role of the food components in allergy might improve diagnosis, treatment, and prevention of food allergy. This review considers the role of the dietary components, including lipids, sugars, polyphenols, and vitamins, in the development of food allergy as well as results of mechanistic investigations in in vivo and in vitro models.