Cutaneous Anaphylaxis Reaction In Mice Research Articles

A novel mouse allergy tested model and its application for traditional Chinese medicine injections's allergy evaluation

When the drug induces the organism to produce a type Ⅰ allergic reaction, the combination of IgE and mast cells results in the degranulation of the mast cells. Release of vasoactive substances, increase in vascular permeability, and exudation of intravascular substances outside the blood vessels. Based on this pathophysiological mechanism, a mouse model that can objectively and quantitatively assess the allergic response to the injection has been established. ICR mice were sensitised by intraperitoneal injection of different doses of OVA once every two days for three times. 14 days after the last sensitization, a combination OVA solution of 4 times the sensitizing dose and Evans blue were injected intravenously into mice for the challenge. Compared with the normal group, OVA 0.625/2.5, 1.25/5, 2.5/10, 5/20 mg·kg~(-1) sensitized and challenged can induce allergic reactions mainly manifested by blue staining of the auricle in mice. Direct injection of OVA intravenously did not cause an auricular blue colouration reaction in mice. The passive cutaneous anaphylaxis reaction in mice was conducted with the aforementioned OVA-sensitized mouse serum, and there were obvious blue spots on the mouse's back. In addition, the content of anti-OVA-IgE in 5 mg·kg~(-1) OVA-sensitized mice was significantly increased. Ears and lungs of mice sensitized to OVA showed evident exudation inflammation. Significantly elevated inflammatory factors(VEGF and IL-10) were also detected in the serum of OVA-sensitized mice. The equivalent dose of OVA caused obvious allergic reactions in both guinea pigs and mice. Compared with nude mice, ICR and BALB/c mice are more sensitive to OVA sensitization. Injections of selected TCMI did not induce type Ⅰ allergic reactions in mice and guinea pigs, but there was a risk of inducing pseu-doallergic reactions in mice. The model is problematic and may well reflect the sensitization effect of allergens. It obtains the benefits of simple operation, accuracy, low cost, easy extension, and high repeatability. It is suitable for predicting and researching for IgE-dependent type Ⅰ allergic reactions.

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.

Docosahexaenoyl ethanolamide mitigates IgE-mediated allergic reactions by inhibiting mast cell degranulation and regulating allergy-related immune cells

Docosahexaenoic acid (DHA) is a long-chain polyunsaturated fatty acid mainly found in fish oil. Although several studies have suggested that it can alleviate allergy symptoms, its mechanism of action remains to be elucidated. In the present study, we found that docosahexaenoyl ethanolamide (DHEA), a metabolite of DHA produced in the human body, exerts the anti-allergic activity in vitro and in vivo. DHEA suppressed degranulation of rat basophilic leukemia RBL-2H3 cells and bone marrow-derived mast cells in a dose-dependent manner without cytotoxicity. This occurred due to a decrease in Ca2+ influx, which is critical for mast cell degranulation. DHEA also suppressed IgE-mediated passive cutaneous anaphylaxis reaction in mice. In addition, DHEA was demonstrated to lessen an allergic symptom in a mouse model of pollinosis and to alter the production of IgE and cytokines secreted by splenocytes collected from the pollinosis mice. Taken together, this study indicates that DHEA is a promising anti-allergic agent as it inhibits mast cell degranulation and modulates other immune cells.

Inhibitory effect of aqueous extract of Cuminum cyminum L. seed on degranulation of RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice.

Cuminum cyminum L. (cumin) seed is used as a spice in various countries. Although several functions of the components in cumin seed have been reported, the anti-allergic effect of the water-soluble component in cumin seed has not been reported yet. In this study, we focused on the suppressive effect of cumin seed aqueous extract on degranulation in order to reveal the anti-allergic effect of cumin. Cumin seed aqueous extract significantly suppressed the antigen-induced degranulation of rat basophilic leukemia cell line RBL-2H3 cells in a dose-dependent manner without cytotoxicity. The extract also inhibited the elevation of the intracellular calcium ion concentration induced by antigen. Immunoblot analysis revealed that the extract suppresses phosphorylation of phosphatidylinositol 3-kinase, Bruton's tyrosine kinase, phospholipase C-γ1/2, and Akt in the signaling pathways activated by antigen induction via FcεRI. Furthermore, the extract suppressed microtubule formation induced by antigen. In addition, oral administration of cumin seed aqueous extract significantly suppressed the passive cutaneous anaphylaxis reaction in BALB/c mice. Our findings suggest that cumin seed contains water-soluble components with the anti-allergic effect. Therefore, cumin seed has potential as anti-allergic functional food.

Inhibitory effect of Japanese black vinegar on IgE-mediated degranulation of RBL-2H3 cells and a murine model of Japanese cedar pollinosis.

Japanese black vinegar (JBV) is a traditional vinegar manufactured with steamed unpolished rice. After screening, beneficial effects of JBV on IgE-mediated allergic responses were found. In this study, acetic acid-free JBV was used to evaluate its antiallergic effects. JBV suppressed degranulation of rat basophilic leukemia RBL-2H3 cells in a dose-dependent manner without cytotoxicity. The inhibitory effect of JBV on the degranulation seemed to be caused by the bioactive ingredients other than proteins, because the activity was not affected by heat treatment or protease digestion. JBV inhibited the elevation in the intracellular Ca2+ concentration induced by antigen. Immunoblot analysis revealed that JBV suppresses degranulation of RBL-2H3 cells by downregulated phosphorylation of PI3K, Akt, and PLCγ1. In addition, oral administration of JBV significantly suppressed passive cutaneous anaphylaxis reaction in mice and an allergic symptom in Cry j1-induced pollinosis model mice. Thus, JBV has a potential as a health-promoting food with the antiallergy effect.

Anti-Allergic Activity of Monoacylated Ascorbic Acid 2-Glucosides.

2-O-α-d-Glucopyranosyl-l-ascorbic acid (AA-2G) is one of the stable ascorbic acid (AA) derivatives known as provitamin C agents. We have previously synthesized two types of monoacylated derivatives of AA-2G, 6-O-acyl-2-O-α-d-glucopyranosyl-l-ascorbic acids having a straight-acyl chain of varying length from C4 to C18 (6-sAcyl-AA-2G) and a branched-acyl chain of varying length from C6 to C16 (6-bAcyl-AA-2G) in order to improve the bioavailability of AA-2G. In this study, 6-sAcyl-AA-2G and 6-bAcyl-AA-2G per se showed the inhibitory effects on hyaluronidase activity and degranulation. 6-sAcyl-AA-2G exhibited strong inhibitory effects on hyaluronidase activity and degranulation in a concentration-dependent manner, and the inhibitory effects tended to become stronger with increasing length of the acyl chain. 2-O-α-d-Glucopyranosyl-6-O-hexadecanoyl-l-ascorbic acid (6-sPalm-AA-2G), which has a straight C16 acyl chain, was the most potent effective for inhibition of hyaluronidase activity and for inhibition of degranulation among the 6-sAcyl-AA-2G derivatives and the two isomers of 6-sPalm-AA-2G. Furthermore, percutaneous administration of 6-sPalm-AA-2G significantly inhibited IgE-mediated passive cutaneous anaphylaxis reaction in mice. These findings suggest that 6-sPalm-AA-2G will be useful for treatment of allergies.

OM-X®, Fermented Vegetables Extract Suppresses Antigen-Stimulated Degranulation in Rat Basophilic Leukemia RBL-2H3 Cells and Passive Cutaneous Anaphylaxis Reaction in Mice

OM-X® is a hand-made and naturally manufactured probiotic supplement. This fermented food product is made from vegetables, fruits, seaweeds and mushrooms, using 12 strains of lactic acid bacteria and bifidobacteria. OM-X® is also known to have beneficial health properties, and some of its components show effects on antigen (Ag)-stimulated degranulation activity, indicating that OM-X® may be useful in the treatment of allergy responses and symptoms. In this study, we evaluated the inhibitory effects of OM-X® on Ag-stimulated degranulation in rat basophilic leukemia RBL-2H3 cells, clarified the underlying mechanisms, and determined the active compounds in OM-X® for suppression of degranulation. Treatment with OM-X® gradually suppressed Ag-stimulated degranulation throughout the maturation period. OM-X® also gradually produced melanoidins by lactic acid bacterial fermentation during the maturation process. There was a high correlation between the suppression levels of Ag-stimulated degranulation and the browning of OM-X®. Furthermore, the inhibition of Ag-stimulated degranulation by OM-X® was found to be partially due to the direct inactivation of NADPH oxidase. To elucidate the in vivo effects of OM- X®, type I allergy model mice were orally administered with OM-X®, and the passive cutaneous anaphylaxis (PCA) reaction was measured. OM-X® intake remarkably suppressed the PCA reaction. Taken together, our findings suggest that OMX® could be a beneficial food to ameliorate allergic reactions.

Flavonoid glucuronides isolated from spinach inhibit IgE-mediated degranulation in basophilic leukemia RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice

We isolated three active constituents from an aqueous extract of spinach leaves by evaluating the inhibitory activity of IgE-mediated degranulation in rat basophilic leukemia RBL-2H3 cells, and determined their chemical structures. These compounds, referred to as SO-1, SO-2 and SO-3, were assessed to be flavonol glucuronides with the same fundamental structure. Among them, SO-1 exhibited the most potent granulation-inhibitory activity at the concentrations of 0.5~10 µg/ml. This inhibitory effect was completely exhibited by its aglycon, which was prepared by the enzymatic treatment of β-glucuronidase and the chromatographic isolation. These compounds hardly showed cytotoxicity at the same concentration range in RBL-2H3 cell culture. To reveal its inhibitory mechanism, we examined the effects of SO-1 on the signal transduction of antigen-stimulated degranulation in the cells. Both SO-1 and its aglycon reduced the elevation of intracellular Ca 2+ concentration in a dose-dependent manner and also effectively inhibited the activation of tyrosine kinases such as Syk and Lyn, which underlay in the upstream of intracellular signal transduction followed by antigen stimulation. Furthermore, both SO-1 and its aglycon remarkably suppressed the passive cutaneous anaphylaxis (PCA) reaction induced in ICR mouse ear, as compared with the authentic anti-allergic drugs. In this PCA reaction, the aglycon exerted more potent inhibitory activity than SO-1, indicating that SO-1 also functions in vivo through the hydrolysis to the aglycon in the gastrointestinal tract. Together with these results, we conclude that spinach contains the promising anti-allergic flavonoid glucuronide, suggesting that this compound and its original vegetable may be beneficial to prevent or ameliorate allergic constitutions of humans.

Counteractive effect of Paeonia lactiflora root constituent mudanpioside E against suppressive effect of Shoseiryuto-extract on passive cutaneous anaphylaxis reaction in mice

Ethnopharmacological relevanceShoseiryuto-extract (SST) is a herbal formula of Japanese traditional kampo medicine used to treat perennial nasal allergy, rhinitis, and bronchial asthma. SST contains eight crude drugs, and is registered in the 16th Edition of Japanese Pharmacopoeia. Previous studies reported anti-allergic effects of SST, but the contribution of the eight crude drugs in SST on these effects has not been evaluated. In the present study, we evaluated the contribution of the eight crude drugs in SST on anti-allergic effect using passive cutaneous anaphylaxis (PCA) reaction in mice. Materials and methodsThe mixture of crude drugs was decocted in water and lyophilized to prepare SST. To evaluate the active ingredients, compositions of crude drugs were modified and decocted. The PCA reaction was induced by intravenous injection of ovalbumin (OVA) and Evans blue 48h after intracutaneous injection of anti-OVA serum in mice ears. The crude drug extract was orally administered to overnight-fasted mice 2h before induction of the PCA reaction. Ears were removed 30min after induction, and the amount of Evans blue present was measured. ResultsOral administration of SST suppressed the PCA reaction in a dose-dependent manner. Among the eight crude drugs comprising SST, Asiasarum root, Pinellia tuber, and Glycyrrhiza contributed positively, and Peony root contributed negatively to the anti-allergic effects of SST. We isolated mudanpioside E from the extract of Peony root as the counteracting ingredient to exhibit the anti-allergic effects of Peony root-depleted SST. ConclusionsWhen we used SST for the treatment of allergic diseases, removal of Peony root from the traditional formula could augment its effect.

Anti-Allergic Action of Aged Black Garlic Extract in RBL-2H3 Cells and Passive Cutaneous Anaphylaxis Reaction in Mice

Garlic (Allium sativum) has been used as a food as well as a component of traditional medicine. Aged black garlic (ABG) is known to have various bioactivities. However, the effect of ABG on allergic response is almost unknown. In the present study, we investigated whether ABG can inhibit immunoglobulin E-mediated allergic response in RBL-2H3 cells as well as in vivo passive cutaneous anaphylaxis (PCA). In in vitro tests, ethyl acetate extract (EBG) of ABG significantly inhibited the release of β-hexosaminidase (IC₅₀, 1.53 mg/mL) and TNF-α (IC₅₀, 0.98 mg/mL). Moreover, BG10, an active fraction of EBG, dramatically suppressed the release of β-hexosaminidase (IC₅₀, 53.60 μg/mL) and TNF-α (IC₅₀, 27.80 μg/mL). In addition, BG10 completely blocked the formation of prostaglandin E₂ and leukotriene B₄ at ≥25 μg/mL. When the effect of BG10 on FcɛRI receptor cascade was investigated, BG10 significantly inhibited the phosphorylation of Syk, but not Lyn. Furthermore, BG10 dose dependently decreased the phosphorylation of cytosolic phospholipase A₂ (cPLA₂) and 5-lipoxygenase (5-LO) as well as the expression of cyclooxygenase-2 (COX-2). Consistent with what has been mentioned earlier, BG10 also significantly inhibited the PCA reaction in mice. In conclusion, these results indicate that ABG suppresses the allergic response, and the mechanism for its anti-allergic action may involve suppressions of Syk, cPLA₂, 5-LO, and COX-2. The anti-allergic actions of ABG, EBG, or BG10 suggest that they may be useful as functional foods for allergic diseases.

Inhibitory effects of an ellagic acid glucoside, okicamelliaside, on antigen-mediated degranulation in rat basophilic leukemia RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice

Degranulation inhibitors in plants are widely used for prevention and treatment of immediate-type allergy. We previously isolated a new ellagic acid glucoside, okicamelliaside (OCS), from Camellia japonica leaves for use as a potent degranulation inhibitor. Crude extracts from leaves also suppressed allergic conjunctivitis in rats. In this study, we evaluated the in vivo effect of OCS using a pure sample and performed in vitro experiments to elucidate the mechanism underlying the extraordinary high potency of OCS and its aglycon. The IC50 values for degranulation of rat basophilic leukemia cells (RBL-2H3) were 14nM for OCS and 3μM for aglycon, indicating that the two compounds were approximately 2 to 3 orders of magnitude more potent than the anti-allergic drugs ketotifen fumarate, DSCG, and tranilast (0.17, 3, and >0.3mM, respectively). Antigen-induced calcium ion (Ca2+) elevation was significantly inhibited by OCS and aglycon at all concentrations tested (p<0.05). Upstream of the Ca2+ elevation in the principle signaling pathway, phosphorylation of Syk (Tyr525/526) and PLCγ-1 (Tyr783 and Ser1248) were inhibited by OCS and aglycon. In DNA microarray-screening test, OCS inhibited expression of proinflammatory cytokines [interleukin (IL)-4 and IL-13], cytokine-producing signaling factors, and prostaglandin-endoperoxidase 2, indicating that OCS broadly inhibits allergic inflammation. During passive cutaneous anaphylaxis in mice, OCS significantly inhibited vascular hyperpermeability by two administration routes: a single intraperitoneal injection at 10mg/kg and per os at 5mg/kg for 7days (p<0.05). These results suggest the potential for OCS to alleviate symptoms of immediate-type allergy.

Inhibitory effect of Lactobacillus plantarum K-1 on passive cutaneous anaphylaxis reaction and scratching behavior in mice

Lactobacillus plantarum K-1 (LP) inhibiting AP-1 (c-Jun) and NF-κB activations was isolated from kimchi, and its inhibitory activity against scratching behavior and passive cutaneous anaphylaxis reaction in mice was investigated. Heat-inactivated LP (heated at 60°C for 30 min) potently inhibited the expression of TNF-α and IL-4 as well as the activation of their transcription factors, NF-κB and c-jun, in phorbol 12'-myristate 13'-acetate-stimulated RBL-2H3 cells. LP (1 × 10(10) CFU per mouse) showed a potent inhibition against passive cutaneous anaphylaxis reaction induced by the IgE-antigen complex in mice, inhibiting it by 87.5%. LP (1 × 10(10) CFU/mouse) inhibited histamine-induced scratching behavior by 58.9% compared to the control group. LP significantly inhibited vascular permeability induced by histamine. The inhibitory activity of LP against vascular permeability was in proportion to its inhibition against scratching behavior. LP potently inhibited histamine-induced cytokine production: it (1 × 10(10) CFU per mouse) inhibited IL-4, IL-1β, and TNF-α expression by 88.9%, 88.6%, and 98.9%, respectively. LP also inhibited IgE level increased by histamine by 85.3%. It inhibited histamine-induced the activations of their transcription factors, NF-κB and c-Jun. Based on these findings, LP may improve allergic diseases, such as anaphylaxis, atopic dermatitis, rhinitis, and pruritus by inhibiting the expression of IgE-switching cytokine IL-4 and proinflammatory cytokines IL-1β and TNF-α via NF-κB and AP-1 signaling pathways.

The ethyl acetate extract of Cordyceps militaris inhibits IgE-mediated allergic responses in mast cells and passive cutaneous anaphylaxis reaction in mice

Cordyceps militaris has been used as a traditional herbal medicine for treating allergy in East Asia. We investigated the anti-allergic efficacy of Cordyceps militaris and its mechanism of action. β-Hexosaminidase release of mast cells, a key parameter of degranulation, was evaluated. Anti-allergic potential of Cordyceps militaris was studied using passive cutaneous anaphylaxis (PCA) in vivo. The anti-allergic mechanism of Cordyceps militaris was investigated by immunoblotting analysis, RT-PCR and other biological approaches in mast cells. GSCM EtOAc extract (GSCME) inhibited antigen-induced degranulation with a IC50 value (28.5 μg/ml) in RBL-2H3 cells and antigen-induced passive cutaneous anaphylaxis (PCA) response with a ED50 value (665 mg/kg) in vivo. The release of interleukin (IL-4) and tumor necrosis factor (TNF-α were decreased by GSCME in RBL-2H3 cells. In order to elucidate the anti-allergic mechanisms of GSCME in mast cells, we examined the activated levels of signaling molecules. GSCME inhibited the phosphorylation Syk, ERK, p38 and JNK expression. Identified genistein, daidzein, genistein 7-O-β-d-glucoside 4″-O-methylate, genistein 4'-O-β-d-glucoside 4″-O-methylate, glycitein 7-O-β-d-glucoside 4″-O-methylate, daidzein 7-O-β-d-glucoside 4″-O-methylate and adenosine in GSCME, inhibited antigen-induced degranulation in RBL-2H3 cells. Our study suggests that GSCME might be used as a therapeutic agent for allergic diseases.

Tanshinones isolated from the rhizome of Salvia miltiorrhiza inhibit passive cutaneous anaphylaxis reaction in mice

The rhizome of Salvia miltiorrhiza Bunge (SM, family Labiatae), which contains tanshinones as main constituents, has been used as a cardiovascular and anti-inflammatory agent in Chinese medicine. This study aimed to elucidate anti-allergic effects of the root of Salvia miltiorrhiza Bunge (SM, family Labiatae) and its main constituents, tanshinones, against passive cutaneous anaphylaxis (PCA) reaction. PCA reaction was induced by IgE-antigen complex (IAC) in ICR mice. Protein expression of IL-4 and TNF-α in rat basophilic leukemia (RBL)-2H3 cells was performed by enzyme-linked immunosorbent assay and NF-κB and c-jun (AP-1) activation assayed by immunoblot. Tanshinones inhibited the PCA reaction and reduced IL-4 and TNF-α production in mice as well as in IAC-stimulated RBL-2H3 cells. Tanshinones also inhibited NF-κB and AP-1 activation in RBL-2H3 cells stimulated with IAC. Among tested tanshinones, tanshinone I exhibited the most potent inhibition, followed by 15,16-dihydrotanshinone I, tanshinone IIA and cryptotanshinone. SM and tanshinones may ameliorate the PCA reaction by inhibiting the allergic cytokines IL-4 and TNF-α via NF-κB and AP-1 pathways.

Inhibitory Effects of Whisky Congeners on IgE-Mediated Degranulation in Rat Basophilic Leukemia RBL-2H3 Cells and Passive Cutaneous Anaphylaxis Reaction in Mice

Whisky is matured in oak casks. Many nonvolatile substances (whisky congeners, WC) seep from the oak cask during the maturing process. In this study, three antiallergic agents (syringaldehyde, SA; lyoniresinol, Lyo; and ellagic acid, EA) were isolated from WC. Treatment with SA, Lyo, and EA reduced the elevation of intracellular free Ca(2+) concentration ([Ca(2+)]i) and intracellular ROS production caused by FcepsilonRI activation. The inhibitions of the elevation of [Ca(2+)]i and intracellular ROS production by SA and Lyo were mainly due to the suppression of the NADPH oxidase activity and scavenging of the produced radical, respectively. On the other hand, EA inactivated spleen tyrosine kinase and led to the inhibition of the elevation of [Ca(2+)]i and intracellular ROS production. Furthermore, it was found that WC strongly inhibited IgE binding to the FcepsilonRIalpha chain, whereas SA, Lyo, and EA did not indicate this inhibitory effect. These results suggest that WC inhibits allergic reactions through multiple mechanisms. To disclose the in vivo effects of WC, SA, Lyo, and EA, these compounds were administered to type I allergic model mice, and the passive cutaneous anaphylaxis (PCA) reaction was measured. These compounds remarkably suppressed the PCA reaction. Taken together, these findings suggest that WC seemed to be beneficial to ameliorate allergic reactions.

Inhibitory Effects of Guarana Seed Extract on Passive Cutaneous Anaphylaxis and Mast Cell Degranulation

This study investigated the effects of guarana seed extract (GSE) on an anti-allergic mechanism. GSE orally administered inhibited the anti-dinitrophenol IgE-induced passive cutaneous anaphylaxis reaction in mice. Furthermore, it inhibited the degranulation of rat basophilic leukemia RBL-2H3 cells. It had no cytotoxicity on RBL-2H3 cells. These results show that GSE is a candidate for effective therapeutic material for allergic diseases.

Compound K, a Metabolite of Ginsenoside Rb1, Inhibits Passive Cutaneous Anaphylaxis Reaction in Mice

To understand the anti-allergic mechanism of compound K, which is a metabolite of ginsenoside Rb1, a main constituent of the root of Panax ginseng C.A. Meyer (family Araliaceae), its inhibitory effect against IgE-antigen complex (IAC)-induced passive cutaneous anaphylaxis (PCA) reaction in mice and mRNA and protein expressions of allergic cytokines in IAC-stimulated RBL-2H3 cells were investigated. Orally administered ginsenoside Rb1 more potently inhibited PCA reaction when administered at 5 h prior to the IAC treatment than when administered at 1 h before. However, compound K orally administered 1 h before IAC treatment showed a more potent anti-PCA reaction effect than when treated at 5 h before. Orally administered ginsenoside Rb1 more potently inhibited PCA reaction induced by IAC in mice than intraperitoneally treated one, apart from orally administered its metabolite, compound K, which was more potent than the orally administered one. The compound K, a metabolite of ginsenoside Rb1, inhibited mRNA and protein expressions of IL-4 and TNF-α and the activation of their transcription factor NF-κB and MAPK in IAC-stimulated RBL-2H3 cells. These findings suggest that orally administered ginsenoside Rb1 may be dependent on its metabolism by intestinal microflora in the intestine and the compound K may improve allergic diseases by the inhibition of IL-4 and TNF-α expresseion.

Inhibitory effects of sesquiterpene lactones isolated from Eupatorium chinense L. on IgE-mediated degranulation in rat basophilic leukemia RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice

Sesquiterpene lactones (SQTLs) have been shown to suppress the degranulation as inferred by histamine release in rat basophilic leukemia RBL-2H3 cells. In this study, we isolated the 9 kinds of SQTLs from Eupatorium chinense L. and examined the effects of these SQTLs on the degranulation in RBL-2H3 cells. The chemical structures of two novel compounds (SQTL-3 and 8) were determined. All the SQTLs suppressed the degranulation from Ag-stimulated RBL-2H3 cells. To disclose the inhibitory mechanism of degranulation by SQTLs, we examined the activation of intracellular signaling molecules such as Lyn, Syk, and PLCγs and intracellular free Ca 2+ concentration ([Ca 2+]i). None of these SQTLs showed the activation of Syk and PLCγs. The intracellular free Ca 2+ concentration ([Ca 2+]i) was elevated by FcεRI activation, but SQTLs treatment reduced the elevation of [Ca 2+]i by suppressing Ca 2+ influx. Thus, it was suggested that the suppression of Ag-stimulated degranulation by these SQTLs is mainly due to the decreased Ca 2+ influx. Furthermore, in order to clarify the in vivo effect of SQTL-rich extract, we administered SQTL-rich extract to the type I allergic model mice and measured the passive cutaneous anaphylaxis (PCA) reaction induced by IgE-antigen complex. The SQTLs remarkably suppressed PCA reaction in a dose-dependent manner. Thus, it was suggested that SQTLs would be a candidate as an anti-allergic agent.

Structure-activity Relationships of 4-Senecioyloxymethyl-6,7-dimethoxycoumarin Analogues as Anti-Allergic Agents

Mast cells are key effector cells in the early phase allergic inflammation and in diverse immunological and pathological processes. In order to understand the effect on reduction of the anti-dinitrophenyl (DNP) IgE antibody-induced β-hexosaminidase release in RBL-2H3 rat mast cells, a novel series of 4-senecioyloxymethyl- 6,7-dimethoxycoumarins (SMDC) was prepared by reacting 4-chloromethyl-6,7-dimethoxycoumarin with various carboxylic acids. Compounds 8-11 with cyclic moiety such as phenyl, thiophenyl, pyridinyl, and furanyl group were found to inhibit-hexosaminidase release more potently (5.98-9.62 μM) than compounds 3- 7 and 12 with acyclic moiety (19.32-76.78 μM). Furthermore, compounds 8 and 9 inhibited IgE-induced ear swelling and significantly reduced systemic passive cutaneous anaphylaxis reaction in mice.

Synthetic studies on novel Syk inhibitors. Part 1: Synthesis and structure–activity relationships of pyrimidine-5-carboxamide derivatives

Spleen tyrosine kinase (Syk) is a non-receptor-type tyrosine kinase which mediates diverse responses in haematopoietic cells. Therefore, Syk is an attractive therapeutic target, and in a study of Syk inhibitors as potentially new therapeutic agents, we discovered the 4-anilinopyrimidine-5-carboxamides. Enzyme screening indicated that an aminoethylamino moiety at the 2-position of the pyrimidine ring was important for Syk inhibitory activity, and an investigation of the substituents at the 4-position revealed that an anilino moiety substituted at the meta position was preferred. These compounds showed high selectivity for Syk, compared to other kinases, such as ZAP-70, c-Src, and PKC, and exhibited good inhibitory activities against 5-HT release from RBL-cells. Among them, compound 9a inhibited the passive cutaneous anaphylaxis reaction in mice, with an ID 50 of 13 mg/kg following subcutaneous administration. These results suggest that our compounds are worthy of further evaluation as new anti-allergic agents.