Degranulation Inhibitors from Medicinal Plants in Antigen-Stimulated Rat Basophilic Leukemia (RBL-2H3) Cells

The peels of sacred Lotus (Nelumbo nucifera) rhizomes suppress allergic reactions by inhibiting the A23187-induced degranulation in rat basophilic leukemia (RBL2H3) cells

We isolated ten compounds from methanolic extract of the peels of sacred lotus (Nelumbo nucifera) rhizomes which were identified as β-sitosterol linoleate 1, β-sitosterol 2, lupeol 3, stigmasterol 3-O-β-D-glucoside 4, oleanolic acid 5, betulinic acid 6, pinoresinol 7, 4-hydroxybenzoic acid 8, catechin 9 and gallocatechin 10. All of the isolated compounds from the peels of sacred lotus rhizomes are reported for the first time, and were investigated for their anti-allergic activity. We found that three of them, stigmasterol 3-O-β-D-glucoside 4, oleanolic acid 5 and pinoresinol 7, were capable of inhibiting A23187-induced degranulation in RBL-2H3 cells with IC50 values 0.18 ± 0.01 mM, 0.28 ± 0.06 mM, and 0.27 ± 0.01 mM, respectively. With an exception to 4, compounds 5 and 7 achieved the anti-allergic effect without affecting the cells viability even at higher concentrations with their selectivity indices (SI) being >5. By reducing A23187-induced degranulation, it is suggestive of a mechanism attenuation of Ca2+ elevation. Our findings suggest that, the peels of sacred lotus rhizomes would be beneficial for providing an inexpensive source for the production of bioactive compounds with anti-allergic effect.

Mast Cells as a Target-A Comprehensive Review of Recent Therapeutic Approaches

Mast cells (MCs) are the immune cells distributed throughout nearly all tissues, mainly in the skin, near blood vessels and lymph vessels, nerves, lungs, and the intestines. Although MCs are essential to the healthy immune response, their overactivity and pathological states can lead to numerous health hazards. The side effect of mast cell activity is usually caused by degranulation. It can be triggered by immunological factors, such as immunoglobulins, lymphocytes, or antigen-antibody complexes, and non-immune factors, such as radiation and pathogens. An intensive reaction of mast cells can even lead to anaphylaxis, one of the most life-threatening allergic reactions. What is more, mast cells play a role in the tumor microenvironment by modulating various events of tumor biology, such as cell proliferation and survival, angiogenesis, invasiveness, and metastasis. The mechanisms of the mast cell actions are still poorly understood, making it difficult to develop therapies for their pathological condition. This review focuses on the possible therapies targeting mast cell degranulation, anaphylaxis, and MC-derived tumors.

Perilla Pomace, a By-product of Oil Extraction, Is Rich in Nutrients and Can Favorably Modulate Lipid Metabolism in Sprague-Dawley Rats

Perilla pomace, a by-product of oil extraction, is rich in nutrients, such as proteins, but it has not been used for purposes other than livestock feeding. The aim of this study was to determine how perilla pomace modulates glucose and lipid metabolism in Sprague-Dawley rats. Dried perilla pomace was added to diet at a concentration of 16%. One experimental group was administered perilla oil equivalent to that in the perilla pomace. After four weeks, the animals were euthanized, and biochemical parameters were measured. Two experiments were conducted using a low-fat (7% by weight) and a high-fat (21% by weight) diet. Regardless of the level of fat in the diets, no differences in food intake were found among the groups. In the low-fat diet-fed rats (Experiment 1), epididymal adipose tissue weight was slightly, but not significantly, lower in perilla pomace-fed rats than in those fed the control diet. Hepatic triglyceride and cholesterol levels were significantly reduced by perilla pomace compared to those in the control group. Serum lipid profiles (triglycerides and cholesterol) were similar to those in the liver, without statistically significant differences. Perilla pomace significantly diminished hepatic fatty acid synthase (FAS) activity. In high-fat diet-fed rats (Experiment 2), pomace did not significantly lower epididymal adipose tissue weight. Hepatic cholesterol levels were lower in rats on the perilla oil than in control rats. The activity of hepatic enzymes involved in fat oxidation was significantly higher in rats fed the perilla pomace than in those fed the control diet. Collectively, these results show that perilla pomace favorably modulates fat metabolism, and the specific effects depend on the fat content in the diet.

In Vitro Effect of Flavonoids on Basophils Degranulation and Intestinal Epithelial Barrier Damage Induced by ω-5 Gliadin-Derived Peptide

Flavonoids have antioxidant, anti-inflammatory and immunomodulatory properties, and may alleviate food allergic reactions and intestinal inflammation induced by ω-5 gliadin, a main allergen of wheat food allergy in children. In this study, a human basophil KU812 cell degranulation model and a Caco-2 monolayer cell model were constructed in vitro to evaluate the effects of four flavonoids on the allergenicity of ω-5 gliadin peptides and ω-5 gliadin peptide-induced barrier damage in Caco-2 intestinal epithelial monolayers. The results show that baicalein, luteolin, isorhamnetin and naringenin can significantly inhibit the degranulation of KU812 cells stimulated by ω-5 gliadin-derived peptide P4 and the release of IL-6 and TNF-α. In addition, the four flavonoids significantly inhibited the ω-5 gliadin-derived peptide P4 to induce the release of IL-6, IL-8 in Caco-2 cells, inhibited the release of zonulin, and significantly increase the expression of tight junction proteins Occludin and ZO-1 in the Caco-2 cell monolayer. In conclusion, baicalein, luteolin, isorhamnetin and naringenin inhibit degranulation stimulated by wheat allergen and enhance intestinal barrier functions, which supports the potential pharmaceutical application of the four flavonoids treatment for wheat food allergy.

Determination of Therapeutic and Safety Effects of Zygophyllum coccineum Extract in Induced Inflammation in Rats

Background

Z. coccineum is a facultative plant with many medicinal applications. This study examined the anti-inflammatory activity of Zygophyllum coccineum (Z. coccineum) in an arthritis animal model.

Materials and Methods

Seventy-Six Wistar Albino rats of either sex randomly divided into six groups (12/each). The inflammation model was done using Complete Freund's Adjuvant in albino rats. The anti-inflammatory activities of the extract were estimated at different dose levels (15.6, 31, and 60 mg/kg) as well as upon using methotrexate (MTX) as a standard drug (0.3 mg/kg). Paw volume and arthritis index scores have been tested in all examined animals' treatments. Histological examination of joints was also performed. Flow cytometric studies were done to isolated osteoclasts. Cytokines assay as well as biochemical testing was done in the examined samples. Results. In vitro studies reported an IC₅₀ of 15.6 μg/ml for Z. coccineum extract in lipoxygenase inhibition assay (L.O.X.). Moreover, it could be noticed that isorhamnetin-3-O-glucoside, tribuloside, and 7-acetoxy-4-methyl coumarin were the most common compounds in Z. coccineum extract separated using L.C.–ESI-TOF–M.S. (liquid chromatography-electrospray ionization ion-trap time-of-flight mass spectrometry). Microscopic examinations of synovial tissue and hind limb muscles revealed the effect of different doses of Z. coccineum extract on restoring chondrocytes and muscles structures. Osteoclast size and apoptotic rate examinations revealed the protective effect of Z. coccineum extract on osteoclast. The results upon induction of animals and upon treatment using of MTX significantly increased apoptotic rate of osteoclast compared to control, while using of 15.6 μg/ml. for Z. coccineum extract lead to recover regular apoptotic rate demonstrating the protective effect of the extract. Z. coccineum extract regulated the secretion of proinflammatory and anti-inflammatory cytokines. Biochemical tests indicated the safety of Z. coccineum extract on kidney and liver functions. Conclusion. Z. coccineum extract has efficient and safe anti-inflammatory potential in an induced rat model.

Perilla pomace obtained from four different varieties have different levels and types of polyphenols and anti-allergic activity

Perilla frutescens (L.) Britton var. frutescens (egoma in Japan) is a traditional oilseed that has several varieties with different photoperiod responses. Although egoma pomace, industrial waste produced during oil extraction, is a rich source of macro- and micro-nutrients such as protein, fiber, minerals, and polyphenols, it has not yet been used for purposes other than livestock feeding. To find out a better use of perilla pomace and its function, we selected four varieties of egoma originating from different regions with different photoperiod responses: two varieties were from Japan, which are broadly cultivated for oilseed and are highly sensitive to light and temperature. The other two varieties from Nepal, which are tolerant to low light and low temperature. Rosmarinic acid-3-O-glucoside, rosmarinic acid, and apigenin-7-O-glucoside were detected as the main polyphenolic constituents in every variety, while apigenin and luteolin were present only in perilla pomace from Japan. In IgE-sensitized RBL-2H3 cells, polyphenols derived from two varieties of Japan suppressed degranulation of mast cells, but those derived from the two varieties of Nepal did not, indicating that apigenin and luteolin may be in part responsible for the anti-allergic response. In addition, it was found that proteins involved in the degranulation signaling pathway, such as PLCγ2, Syk, and Akt, were less phosphorylated in cells treated with the egoma pomace extracts of Japanese origin. Taken together, pomace from egoma varieties derived from different regions may differently modulate allergic response in part due to the difference in polyphenol composition and may be applied to develop nutraceuticals and functional foods fortified with anti-allergic properties.

Immunomodulatory Role of Nutrients: How Can Pulmonary Dysfunctions Improve?

Nutrition is an important tool that can be used to modulate the immune response during infectious diseases. In addition, through diet, important substrates are acquired for the biosynthesis of regulatory molecules in the immune response, influencing the progression and treatment of chronic lung diseases, such as asthma and chronic obstructive pulmonary disease (COPD). In this way, nutrition can promote lung health status. A range of nutrients, such as vitamins (A, C, D, and E), minerals (zinc, selenium, iron, and magnesium), flavonoids and fatty acids, play important roles in reducing the risk of pulmonary chronic diseases and viral infections. Through their antioxidant and anti-inflammatory effects, nutrients are associated with better lung function and a lower risk of complications since they can decrease the harmful effects from the immune system during the inflammatory response. In addition, bioactive compounds can even contribute to epigenetic changes, including histone deacetylase (HDAC) modifications that inhibit the transcription of proinflammatory cytokines, which can contribute to the maintenance of homeostasis in the context of infections and chronic inflammatory diseases. These nutrients also play an important role in activating immune responses against pathogens, which can help the immune system during infections. Here, we provide an updated overview of the roles played by dietary factors and how they can affect respiratory health. Therefore, we will show the anti-inflammatory role of flavonoids, fatty acids, vitamins and microbiota, important for the control of chronic inflammatory diseases and allergies, in addition to the antiviral role of vitamins, flavonoids, and minerals during pulmonary viral infections, addressing the mechanisms involved in each function. These mechanisms are interesting in the discussion of perspectives associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and its pulmonary complications since patients with severe disease have vitamins deficiency, especially vitamin D. In addition, researches with the use of flavonoids have been shown to decrease viral replication in vitro. This way, a full understanding of dietary influences can improve the lung health of patients.

Sodium Sulfite-Induced Mast Cell Pyroptosis and Degranulation

Sodium sulfite, a common food additive, has been proved to cause allergic reaction. Pyroptosis is an inflammatory form of programmed cell death with plasma membrane lysis. In this study, we found that sodium sulfite triggered pyroptosis, which depended on reactive oxygen species (ROS)/NOD-like receptor protein 3 (NLRP3) in RBL-2H3 mast cells. Sodium sulfite increased the generation of ROS and the expression of NLRP3, caspase-1, gasdermin D N-terminal (GSDMD-N), interleukin-1β (IL-1β), and interleukin-18 (IL-18). The ROS scavenger N-acetyl-L-carnosine (NAC) and the NLRP3 inhibitor MCC950 reversed these effects. Furthermore, using a lactate dehydrogenase kit, propidium iodide staining, scanning electron microscopy, colocalization of GSDMD-N with histamine, and neutral red staining, we found that sodium sulfite notably induced cell membrane rupture. Because β-Hexosaminidase and histamine play a key role in allergic reactions, we detected the release of β-Hexosaminidase and histamine. The data showed that the release of β-Hexosaminidase and histamine induced by sodium sulfite was increased with dose independence, which were inhibited after treatment with NAC or MCC950. Overall, evidence suggested that pyroptosis induced by sodium sulfite may rupture the cell membrane and result in degranulation of mast cells. Our study may provide new insights for the mechanism by which sodium sulfite induces mast cell death and sensitization.

Inhibitory effects of cyanidin-3-O-glucoside in black soybean hull extract on RBL-2H3 cells degranulation and passive cutaneous anaphylaxis reaction in mice

Black soybean hull extract (BSHE) exhibits a variety of biological activities. However, little is known about the effects of BSHE on immunoglobulin E (IgE)-mediated type I allergic reactions. The anti-allergic effect of BSHE was assessed with the degranulation assay using rat basophilic leukemia RBL-2H3 cells and the passive cutaneous anaphylaxis (PCA) reaction in mice. An active compound in BSHE was identified by ultra-performance liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry analysis. BSHE inhibited the release of β-hexosaminidase and histamine in RBL-2H3 cells, and cyanidin-3-O-glucoside (C3G) was identified as one of its active compounds. Oral administering of 200 μmol/kg of C3G to IgE-sensitized mice prior to antigen injection suppressed the PCA reaction, as compared with control (p < 0.01). Intravenous administration of BSHE (C3G content, 5.4%) more strongly inhibited PCA responses at lower doses (100 mg/kg, p < 0.01) than oral administration (1,000 mg/kg, p = 0.059). Intravenous C3G also suppressed PCA response at a low dose (40 mg/kg, p < 0.05), showing the same trend as BSHE. This information can be useful to design appropriate formulations of anthocyanin-based drug products to suppress allergic reactions. This study provides evidence for the potential use of BSHE and C3G for the prevention or the treatment of type I allergies.

Enzymatically synthesized glycogen inhibited degranulation and inflammatory responses through stimulation of intestine

The patients of type I allergic diseases were increased in the developed countries. Recently, many studies have focused on food factors with anti-allergic activities. Enzymatically synthesized glycogen, a polysaccharide with a multi-branched α-1,4 and α-1,6 linkages, is a commercially available product from natural plant starch, and has immunostimulation activity. However, effect of enzymatically synthesized glycogen on the anti-allergic activity was unclear yet. In this study, we investigated that enzymatically synthesized glycogen inhibited allergic and inflammatory responses using a co-culture system consisting of Caco-2 and RBL-2H3 cells. Enzymatically synthesized glycogen inhibited antigen-induced β-hexosaminidase release and production of TNF-α and IL-6 in RBL-2H3 cells in the co-culture system. Furthermore, enzymatically synthesized glycogen inhibited antigen-induced phosphorylation of tyrosine kinases, phospholipase C γ1/2, mitogen-activated protein kinases and Akt. Anti-allergic and anti-inflammatory activities of enzymatically synthesized glycogen were indirect action through stimulating Caco-2 cells, but not by the direct interaction with RBL-2H3 cells, because enzymatically synthesized glycogen did not permeate Caco-2 cells. These findings suggest that enzymatically synthesized glycogen is an effective food ingredient for prevention of type I allergy through stimulating the intestinal cells.

Physiological genetics, chemical composition, health benefits and toxicology of tea (Camellia sinensis L.) flower: A review

The flower of tea (Camellia sinensis L.) plant has been paid an increasing attention in the last twenty years, since it was found that tea flowers contained representative constituents similar to those of tea leaves, such as catechins, caffeine and amino acids. Tea flower is theoretically valuable although it has been considered as an industrial waste over a long period of time. This review summarizes the research findings conducted until now on physiological genetics, chemical composition, health benefits and toxicology of tea flowers, aiming to foresee their future applications. A lot of genes are involved in flower development and the synthesis and transmission of various chemicals in tea flowers. The chemical composition of tea flower consists mainly of catechins, polysaccharides, proteins, amino acids and saponins and thus tea flower possesses various health benefits such as antioxidant, anti-inflammatory, immunostimulating, antitumor, hypoglycemic, anti-obesity and anti-allergic activities. Moreover, tea flower contains a protease that can elevate the free amino acids content in the tea infusion by almost two folds. More importantly, the enzymatic activity of the protease is much higher than that of the commercially available proteases. Additionally, aqueous extracts of tea flower are demonstrated to safe to animals. Thus, the potential uses of tea flowers in food and medical fields are warranted.

Panax ginseng-derived fraction BIOGF1K reduces atopic dermatitis responses via suppression of mitogen-activated protein kinase signaling pathway

Background

BIOGF1K, a fraction of Panax ginseng, has desirable antimelanogenic, anti-inflammatory, and antiphotoaging properties that could be useful for treating skin conditions. Because its potential positive effects on allergic reactions in skin have not yet been described in detail, this study's main objective was to determine its efficacy in the treatment of atopic dermatitis (AD).

Methods

High-performance liquid chromatography was used to verify the compounds in BIOGF1K, and we used the (3-4-5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide method to determine its cytotoxicity in RBL-2H3 and HMC-1 cell lines. RBL-2H3 cells were induced using both anti–DNP-IgE/DNP-BSA and calcium ionophore (A2187) treatments, whereas HMC-1 cells were induced using A2187 alone. To measure mast cell degranulation, we performed histamine (enzyme-linked immunosorbent assay) and β-hexosaminidase assays. To quantify interleukin (IL)-4, IL-5, and IL-13 levels in RBL-2H3 cells, we performed quantitative polymerase chain reaction (PCR); to quantify expression levels of IL-4 and IL-13 in HMC-1 cells, we used semiquantitative reverse transcription polymerase chain reaction (RT-PCR). Finally, we detected the total and phosphorylated forms of extracellular signal-regulated kinase, p-38, and c-Jun N-terminal kinase proteins by immunoblotting.

Results

BIOGF1K decreased the AD response by reducing both histamine and β-hexosaminidase release as well as reducing the secretion levels of IL-4, IL-5, and IL-13 in RBL-2H3 cells and IL-4 and IL-13 in HMC-1 cells. In addition, BIOGF1K decreased MAPK pathway activation in RBL-2H3 and HMC-1 cells.

Conclusions

BIOGF1K attenuated the AD response, hence supporting its use as a promising and natural approach for treating AD.

Imperatorin Suppresses Anaphylactic Reaction and IgE-Mediated Allergic Responses by Inhibiting Multiple Steps of FceRI Signaling in Mast Cells: IMP Alleviates Allergic Responses in PCA

This study is to investigate the effects of imperatorin (IMP) on allergic responses mediated by mast cells, both in vitro and in vivo. Passive cutaneous anaphylaxis (PCA) model was established. Histological detection was performed to assess the ear histology. ELISA and Western blot analysis were used to detect the levels of corresponding cytokines and signalling pathway proteins. IMP decreased the leakage of Evans blue and the ear thickness in the PCA models, in a dose-dependent manner, and alleviated the degranulation of mast cells. Moreover, IMP reduced the expression of TNF-α, IL-4, IL-1β, IL-8, and IL-13. Furthermore, IMP inhibited the phosphorylation levels of Syk, Lyn, PLC-γ1, and Gab2, as well as the downstream MAPK, PI3K/AKT, and NF-κB signaling pathways. In addition, IMP inhibited the mast cell-mediated allergic responses through the Nrf2/HO-1 pathway. IMP attenuates the allergic responses through inhibiting the degranulation and decreasing the expression levels of proinflammatory cytokines in the mast cells, involving the PI3K/Akt, MAPK, NF-κB, and Nrf2/HO-1 pathways.

Immunomodulation Effects of Schizonepeta tenuifolia Briq. on the IgE-Induced Allergic Model of RBL-2H3 Cells

Schizonepeta tenuifolia (ST) Briq. is a traditional herbal medicine commonly used to treat allergic skin diseases, where the inflammation process is closely related to symptom severity. This study aimed to explore the immunomodulatory effect of ST by using immunoglobulin E- (IgE-) stimulated RBL-2H3 cell cultures, a common cell line for studying mast cell degranulation and inflammatory cytokine release in vitro. After stimulating the RBL-2H3 cells with IgE, ST at concentrations of 10, 50, or 100 μg/mL was added to the cell cultures. Cell viability, inflammatory cytokines (IL-6, IL-13, IL-4, TNF-α, and IFN-γ), anti-inflammatory cytokine IL-10, and degranulation ability were examined 48 and 72 hours after administration of ST. The markers of inflammation and allergic reaction, IFN-γ, TNF-α, IL-4, and IL-6, were suppressed, especially after treatment with 100 μg/mL ST. However, the anti-inflammation marker IL-10 was also suppressed by ST. Trend analysis showed that a higher ST concentration was associated with lower IFN-γ and TNF-α levels. Moreover, degranulation of RBL-2H3 cells was assessed by measuring the release of β-hexosaminidase, which was suppressed by ST at 10 μg/mL. This study showed an immunomodulatory effect of ST at the cellular level and suggests the role of ST in treating allergic diseases.

Small molecules that inhibit the late stage of Munc13-4-dependent secretory granule exocytosis in mast cells

Ca²⁺-dependent secretory granule fusion with the plasma membrane is the final step for the exocytic release of inflammatory mediators, neuropeptides, and peptide hormones. Secretory cells use a similar protein machinery at late steps in the regulated secretory pathway, employing protein isoforms from the Rab, Sec1/Munc18, Munc13/CAPS, SNARE, and synaptotagmin protein families. However, no small-molecule inhibitors of secretory granule exocytosis that target these proteins are currently available but could have clinical utility. Here we utilized a high-throughput screen of a 25,000-compound library that identified 129 small-molecule inhibitors of Ca²⁺-triggered secretory granule exocytosis in RBL-2H3 mast cells. These inhibitors broadly fell into six different chemical classes, and follow-up permeable cell and liposome fusion assays identified the target for one class of these inhibitors. A family of 2-aminobenzothiazoles (termed benzothiazole exocytosis inhibitors or bexins) was found to inhibit mast cell secretory granule fusion by acting on a Ca²⁺-dependent, C2 domain–containing priming factor, Munc13-4. Our findings further indicated that bexins interfere with Munc13-4–membrane interactions and thereby inhibit Munc13-4–dependent membrane fusion. We conclude that bexins represent a class of specific secretory pathway inhibitors with potential as therapeutic agents.

Occurrence of Functional Molecules in the Flowers of Tea (Camellia sinensis) Plants: Evidence for a Second Resource

Tea (Camellia sinensis) is an important crop, and its leaves are used to make the most widely consumed beverage, aside from water. People have been using leaves from tea plants to make teas for a long time. However, less attention has been paid to the flowers of tea plants, which is a waste of an abundant resource. In the past 15 years, researchers have attempted to discover, identify, and evaluate functional molecules from tea flowers, and have made insightful and useful discoveries. Here, we summarize the recent investigations into these functional molecules in tea flowers, including functional molecules similar to those in tea leaves, as well as the preponderant functional molecules in tea flowers. Tea flowers contain representative metabolites similar to those of tea leaves, such as catechins, flavonols, caffeine, and amino acids. The preponderant functional molecules in tea flowers include saponins, polysaccharides, aromatic compounds, spermidine derivatives, and functional proteins. We also review the safety and biological functions of tea flowers. Tea flower extracts are proposed to be of no toxicological concern based on evidence from the evaluation of mutagenicity, and acute and subchronic toxicity in rats. The presence of many functional metabolites in tea flowers indicates that tea flowers possess diverse biological functions, which are mostly related to catechins, polysaccharides, and saponins. Finally, we discuss the potential for, and challenges facing, future applications of tea flowers as a second resource from tea plants.

Identification of degranulation inhibitors from rooibos (Aspalathus linearis) tea in rat basophilic leukaemia cells

Quercetin, luteolin and chrysoeriol were identified from rooibos tea as degranulation inhibitors in rat basophilic leukaemia cells. The degranulation inhibitory activity of chrysoeriol was first discovered in the present study. When quercetin, luteolin and chrysoeriol were mixed in the ratio that occurs in rooibos tea extract, the mixture inhibited antigen- and calcium ionophore-stimulated degranulation to the same degree as that by the whole rooibos tea extract. These findings indicate that these three flavonoids are the key factors underlying the degranulation inhibitory activity of rooibos tea.

Diospyros kaki calyx inhibits immediate-type hypersensitivity via the reduction of mast cell activation

CONTEXT

Diospyros kaki L. (Ebenaceae) fruit is widely distributed in Asia and is known to exert anti-inflammatory and antithrombotic effects.

OBJECTIVE

We evaluated the inhibitory effect of aqueous extract of D. kaki calyx (AEDKC) on mast cell-mediated immediate-type hypersensitivity and underlying mechanism of action.

MATERIALS AND METHODS

For in vivo, ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) and immunoglobulin (Ig) E-mediated passive cutaneous anaphylaxis (PCA) models were used. In the ASA, AEDKC (1-100 mg/kg) was orally administered 3 times during 14 days. In the PCA, AEDKC was orally treated 1 h before the antigen challenge. The control drug dexamethasone was used to compare the effectiveness of AEDKC. For in vitro, IgE-stimulated RBL-2H3 cells and primary cultured peritoneal mast cells were used to determine the role of AEDKC (0.01-1 mg/mL).

RESULTS

Oral administration of AEDKC dose dependently suppressed rectal temperature decrease and increases in serum histamine, total IgE, OVA-specific IgE, and interleukin (IL)-4 in the ASA. In the PCA, AEDKC reduced Evans blue pigmentation. Compared to dexamethasone (10 mg/kg), AEDKC (100 mg/kg) showed similar inhibitory effects in vivo. AEDKC concentration dependently suppressed the release of histamine and β-hexosaminidase through the reduction of intracellular calcium in mast cells. In addition, AEDKC decreased the expression and secretion of tumour necrosis factor-α and IL-4 by the reduction of nuclear factor-κB. The inhibitory potential of AEDKC (1 mg/mL) was similar with dexamethasone (10 μM) in vitro.

CONCLUSIONS

We suggest that AEDKC may be a potential candidate for the treatment of mast cell-mediated allergic diseases.

Flavonoids as detoxifying and pro-survival agents: What's new?

The role of flavonoids in the survival machinery of cells has come in the spotlight due to the recent evidence of their effect on the relationship mitochondria-ER stress-proteasome, including the intracellular mechanisms of autophagy and apoptosis. Numerous experimental animal investigations and even human clinical studies have highlighted the major role of these natural compounds in the economy of life and their deep relationship with autotrophic organisms in the evolutionary space. Their role as anti-oxidant and oxidative stress preventive molecules has to date been investigated extensively in the literature. Despite this great amount of promising evidence, many concerns, however, remain, most of which dealing with biochemistry, bioavailability, pharmacokinetics, and interaction of flavonoids with gut microbiome, issues that make difficult any good attempt to introduce these molecules in the human healthcare systems as possible, encouraging therapeutic substances. This review tries to address and elucidate these items.

Pinocembrin, a novel histidine decarboxylase inhibitor with anti-allergic potential in in vitro

Pinocembrin (5, 7- dihydroxy flavanone) is the most abundant chiral flavonoid found in propolis, exhibiting antioxidant, antimicrobial and anti-inflammatory properties. However, the effect of Pinocembrin on allergic response is unexplored. Thus, current study aimed at investigating the effects of Pinocembrin on IgE-mediated allergic response in vitro. A special emphasis was directed toward histidine decarboxylase (HDC) and other pro-allergic and pro-inflammatory mediators. Preliminary studies, using a microbiological model of Klebsiella pneumoniae, provided first evidences that suggest Pinocembrin as a potential thermal stable inhibitor for HDC. Applying docking analysis revealed possible interaction between Pinocembrin and mammalian HDC. In vitro studies validated the predicted interaction and showed that Pinocembrin inhibits HDC activity and histamine in IgE-sensitized RBL-2H3 in response to dinitrophenol (DNP)-bovine serum albumin (BSA) stimulation. In addition, Pinocembrin mitigated the damage in the mitochondrial membrane, formation of cytoplasmic granules and degranulation as indicated by lower β-hexoseaminidase level. Interestingly, it reduced range of pro-inflammatory mediators in the IgE-mediated allergic response including tumor necrosis factor (TNF)-α, interleukin (IL)-6, nitric oxide (NO), inducible NO synthase (iNOS), phosphorylation of inhibitory kappa B (IкB)-α, prostaglandin (PGE)-2 and cyclooxygenase (COX)-2. In conclusion, current study suggests Pinocembrin as a potential HDC inhibitor, and provides the first evidences it is in vitro anti-allergic properties, suggesting Pinocembrin as a new candidate for natural anti-allergic drugs.

Anti-allergic triterpenes isolated from olive milled waste

The degranulation of basophils stimulated by antigen is one of the allergic mechanisms of immediate hypersensitivity reactions. In a previous study, the β-hexosaminidase release of rat basophilic leukemia (RBL-2H3) cells stimulated by IgE cross-linking was specifically inhibited by ethanol extract of olive milled waste (OMW). OMW is a potential source of triterpenes, which show several biological activities. However, little is known about the effect of triterpenes in OMW on β-hexosaminidase release. Here we investigated anti-allergic triterpenes from the ethanol extract of OMW, and we discuss the structure-activity relationship. We subjected ethanol extract of OMW to activity-guided fractionation; this led to the isolation of five known triterpenes, i.e., maslinic acid (1), oleanolic acid (2), punicanolic acid (3), 2-O-acetylmaslinic acid (4), and epimaslinic acid (5) as well as one new triterpene, 11-oxo-maslinic acid (6). An anti-allergic assay revealed that 2-O-acetylmaslinic acid (4) and 11-oxo-maslinic acid (6) showed anti-allergic activity. Considering the structure-activity relationship of these triterpenes, it appears that the existence of a ketone group at C-11 or an acetyl group at C-2 would influence the anti-allergic activity.

New biofunctional effects of the flower buds of Camellia sinensis and its bioactive acylated oleanane-type triterpene oligoglycosides

We review the biofunctional effects of the flower buds of Camellia sinensis and C. sinensis var. assamica, such as antihyperlipidemic, antihyperglycemic, antiobesity, and gastroprotective effects in vivo, and antiallergic, pancreatic lipase inhibitory, and amyloid β (Aβ) aggregation inhibitory activities in vitro. Although the biofunctional effects of tea leaves have been extensively studied, less attention has been given to those of the flowers and seeds of the tea plant. Our studies focused on the saponin constituents of the extracts of the flower buds of C. sinensis cultivated in Japan and China, and C. sinensis var. assamica cultivated in India, and we review their beneficial biofunctions for health promotion.

Inhibitory Effects of Echinochrome A, Isolated from Shell of the Sea Urchin Anthocidaris crassispina, on Antigen-Stimulated Degranulation in Rat Basophilic Leukemia RBL-2H3 Cells through Suppression of Lyn Activation

Echinochrome A (Echi-A) was isolated from the sea urchin Anthocidaris crassispina and its structure determined using 1D and 2D-NMR. In the present study, we examined the inhibitory effect of Echi-A on antigen-stimulated degranulation in rat basophilic leukemia RBL-2H3 cells, which were suppressed in a dose dependent manner. The antigens bind to the high affinity immunoglobulin E receptor, which is expressed on the surface of mast cells and basophils and activate intracellular signal transduction, resulting in the release of biologically active mediators such as histamine. In order to disclose the inhibitory mechanisms of degranulation by Echi-A, we examined the elevation in intracellular Ca2+ concentration ([Ca2+]i), production levels of intracellular reactive oxygen species (ROS) and early intracellular signaling events. Both elevation of [Ca2+]i and intracellular ROS production were markedly suppressed in cells treated with Echi-A. Echi-A also suppressed the activation of Lyn, Syk, and PLCγ1/2 in antigen-stimulated cells. These results indicated that inhibition of antigen-stimulated degranulation in RBL-2H3 cells by Echi-A is mainly due to the inactivation of Lyn/Syk/PLCγ signaling pathways. Our findings suggest that Echi-A could be a beneficial agent for alleviating the symptoms of type I allergy.