Synthesis and evaluation of new potential anti-pseudo-allergic agents.

Pseudo-allergic reactions frequently occur following clinical drug use and sometimes even cause mortal danger. Mas-related G-protein-coupled receptor member X2 (MRGPRX2) is a novel receptor that mediates pseudo-allergy and is an important target in the treatment of allergies. However, to date, there are no synthetic small-molecule inhibitors that prevent anaphylactoid reactions through this pathway. Our preliminary research suggested that B10-S and mubritinib effectively inhibited LAD2 cells. Therefore, two novel derivatives were synthesized by integrating the active substructures of B10-S and mubritinib, according to the molecular docking results. The antiallergic inhibitory effects of the two compounds were preliminarily evaluated in vitro using ß-hexosaminidase release, histamine release, and intracellular Ca2+ mobilization assays, and their binding sites on MRGPRX2 were analyzed by molecular docking. Both substances inhibited ß-hexosaminidase and histamine release in LAD2 cells and decreased intracellular Ca2+ by inhibiting MRGPRX2 in MRGPRX2-HEK293 cells treated with C48/80 in a dose-dependent manner. The docking results suggested that the molecules could competitively bind to the active site on MRGPRX2 and Glu141, which were combined by C48/80. Our study indicated that the two compounds have potential anti-allergic properties, which may provide evidence that will facilitate the development of synthetic molecules with anti-pseudo-allergic activity for clinical use in the future.

Discovery of Potent Antiallergic Agents Based on an o-Aminopyridinyl Alkynyl Scaffold.

Effective therapeutic agents are highly desired for immune-mediated allergic diseases. Herein, we report the design, synthesis, and structure-activity relationship of an o-aminopyridinyl alkyne series as novel orally bioavailable antiallergic agents, which was identified through phenotypic screening. Compound optimization yielded a highly potent compound 36, which effectively suppressed mast cell degranulation in a dose-dependent manner (IC50, 2.54 nM for RBL-2H3 cells; 48.28 nM for peritoneal mast cells (PMCs)) with a good therapeutic index. It also regulated the activation of FcεRI-mediated downstream signaling proteins in IgE/Ag-stimulated RBL-2H3 cells. In addition, 36 exhibited excellent in vivo pharmacokinetic properties and antiallergic efficacy in both passive systemic anaphylaxis (PSA) and house dust mite (HDM)-induced murine models of pulmonary allergic inflammation. Furthermore, preliminary analysis of the kinases profile identified Src-family kinases as potential targets for 36. Compound 36 may serve as a new valuable lead compound for future antiallergic drug discovery.

Antiallergic Activity of 6-Deoxy-2-O-methyl-6-(N-hexadecanoyl)amino-l-ascorbic Acid.

Allergy is an excessive immune response to a specific antigen. Type I allergies, such as hay fever and food allergies, have increased significantly in recent years and have become a worldwide problem. We previously reported that an ascorbic acid derivative having palmitoyl and glucosyl groups, 2-O-α-d-glucopyranosyl-6-O-hexadecanoyl-l-ascorbic acid (6-sPalm-AA-2G), showed inhibitory effects on degranulation in vitro and on the passive cutaneous anaphylaxis (PCA) reaction in mice. In this study, several palmitoyl derivatives of ascorbic acid were synthesized and a structure-activity relationship study was performed to discover more potent ascorbic acid derivatives with degranulation inhibitory activity. 6-Deoxy-2-O-methyl-6-(N-hexadecanoyl)amino-l-ascorbic acid (2-Me-6-N-Palm-AA), in which a methyl group was introduced into the hydroxyl group at the C-2 position of ascorbic acid and in which the hydroxyl group at the C-6 position was substituted with an N-palmitoyl group, exhibited much higher inhibitory activity for degranulation in vitro than did 6-sPalm-AA-2G. 2-Me-6-N-Palm-AA strongly inhibit the PCA reaction in mice at lower doses than those of 6-sPalm-AA-2G. These findings suggest that 2-Me-6-N-Palm-AA may be a promising therapeutic candidate for allergic diseases.

Inhibition of allergen-induced dermal eosinophilia by an oxoeicosanoid receptor antagonist in non-human primates.

BACKGROUND AND PURPOSE: 5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE), acting via the OXE receptor, is unique among 5-lipoxygenase products in its ability to directly induce human eosinophil migration, suggesting its involvement in eosinophilic diseases. To address this hypothesis, we synthesized selective indole-based OXE receptor antagonists. Because rodents lack an OXE receptor orthologue, we sought to determine whether these antagonists could attenuate allergen-induced skin eosinophilia in sensitized monkeys. EXPERIMENTAL APPROACH: In a pilot study, cynomolgus monkeys with environmentally acquired sensitivity to Ascaris suum were treated orally with the "first-generation" OXE antagonist 230 prior to intradermal injection of 5-oxo-ETE or Ascaris extract. Eosinophils were evaluated in punch biopsy samples taken 6 or 24 hr later. We subsequently treated captive-bred rhesus monkeys sensitized to house dust mite (HDM) allergen with a more recently developed OXE antagonist, S-Y048, and evaluated its effects on dermal eosinophilia induced by either 5-oxo-ETE or HDM. KEY RESULTS: In a pilot experiment, both 5-oxo-ETE and Ascaris extract induced dermal eosinophilia in cynomolgus monkeys, which appeared to be reduced by 230. Subsequently, we found that the related OXE antagonist S-Y048 is a highly potent inhibitor of 5-oxo-ETE-induced activation of rhesus monkey eosinophils in vitro and has a half-life in plasma of about 6 hr after oral administration. S-Y048 significantly inhibited eosinophil infiltration into the skin in response to both intradermally administered 5-oxo-ETE and HDM. CONCLUSIONS AND IMPLICATIONS: 5-Oxo-ETE may play an important role in allergen-induced eosinophilia. Blocking its effects with S-Y048 may provide a novel therapeutic approach for eosinophilic diseases.

Novel highly potent OXE receptor antagonists with prolonged plasma lifetimes that are converted to active metabolites in vivo in monkeys.

BACKGROUND AND PURPOSE: The 5-lipoxygenase product 5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-oxo-ETE), acting through the OXE receptor, is a potent eosinophil chemoattractant that may be an important proinflammatory mediator in eosinophilic diseases such as asthma. We previously identified a series of indole-based OXE receptor antagonists that rapidly appear in the blood following oral administration but have limited lifetimes. The objective of this study was to increase the potency and plasma half-lives of these compounds and thereby identify the optimal candidate for future preclinical studies in monkeys, as rodents do not have an OXE receptor orthologue. EXPERIMENTAL APPROACH: We synthesized a series of substituted phenylalkyl indoles and compared their antagonist potencies, pharmacokinetics, and metabolism to those of our earlier compounds. The potencies of some of their metabolites were also investigated. KEY RESULTS: Among the compounds tested, the S-enantiomer of the m-chlorophenyl compound (S-Y048) was the most potent, with an pIC50 of about 10.8 for inhibition of 5-oxo-ETE-induced calcium mobilization in human neutrophils. When administered orally to cynomolgus monkeys, S-Y048 rapidly appeared in the blood and had a half-life in plasma of over 7 hr, considerably longer than any of the other OXE analogues tested. A major hydroxylated metabolite, with a potency close to that of its precursor, was identified in plasma. CONCLUSION AND IMPLICATIONS: Because of its highly potent antagonist activity and its long lifetime in vivo, S-Y048 may be a useful anti-inflammatory agent for the treatment of eosinophilic diseases such as asthma, allergic rhinitis, and atopic dermatitis.

Synthesis of Daidzein Glycosides, α-Tocopherol Glycosides, Hesperetin Glycosides by Bioconversion and Their Potential for Anti-Allergic Functional-Foods and Cosmetics.

Daidzein is a common isoflavone, having multiple biological effects such as anti-inflammation, anti-allergy, and anti-aging. α-Tocopherol is the tocopherol isoform with the highest vitamin E activity including anti-allergic activity and anti-cancer activity. Hesperetin is a flavone, which shows potent anti-inflammatory effects. These compounds have shortcomings, i.e., water-insolubility and poor absorption after oral administration. The glycosylation of bioactive compounds can enhance their water-solubility, physicochemical stability, intestinal absorption, and biological half-life, and improve their bio- and pharmacological properties. They were transformed by cultured Nicotiana tabacum cells to 7-ß-glucoside and 7-ß-gentiobioside of daidzein, and 3'- and 7-ß-glucosides, 3',7-ß-diglucoside, and 7-ß-gentiobioside of hesperetin. Daidzein and α-tocopherol were glycosylated by galactosylation with ß-glucosidase to give 4'- and 7-ß-galactosides of daidzein, which were new compounds, and α-tocopherol 6-ß-galactoside. These nine glycosides showed higher anti-allergic activity, i.e., inhibitory activity toward histamine release from rat peritoneal mast cells, than their respective aglycones. In addition, these glycosides showed higher tyrosinase inhibitory activity than the corresponding aglycones. Glycosylation of daidzein, α-tocopherol, and hesperetin greatly improved their biological activities.

Structure-Activity Relationships of Baicalein and its Analogs as Novel TSLP Inhibitors.

Thymic stromal lymphopoietin (TSLP) plays an important role in the differentiation and proliferation of Th2 cells, resulting in eosinophilic inflammation and numerous allergic diseases. Baicalein (1), a major component of Scutellaria baicalensis, was found to be the first small molecule to block TSLP signaling pathways. It inhibited effectively eosinophil infiltration in house dust mite-induced and ovalbumin-challenged mouse models. Structure-activity relationship studies identified compound 11a, a biphenyl flavanone analog, as a novel human TSLP inhibitor for the discovery and development of new anti-allergic drugs.

Synthesis of new Cu(II)-benzohydrazide nanometer complexes, spectral, modeling, CT-DNA binding with potential anti-inflammatory and anti-allergic theoretical features.

New nanometer Cu(II)-benzohydrazide complexes were synthesized and characterized. Mono negative tetra-dentate mode is the general feature proposed for all coordinating ligands. Variable structural forms were established, square-planer, tetrahedral and octahedral arrangements around copper centers. XRD and TEM studies displayed a nanometer size for crystalline compounds. TGA analysis of new complexes showed low thermal stability due to the presence of crystal water molecules. Kinetic parameters were calculated using two comparative methods for assertion. ESR study was performed on three chosen complexes to estimate essential spectral parameters and assert on proposed geometries. Gaussian09 software program and applying DFT/B3LYP method was used for optimizing all structures to give the best arrangement for atoms. Essential indexes were extracted from log files as well as other indexes were computed based on frontier energy gaps. Potential theoretical anti-inflammatory, antitumor and anti-allergic studies were executed using Autodock 4.2 tools. Essential energies were calculated over docking complexes corresponding to 5HN1, 5AV1 and 4H1L protein receptors for three pathogens (inflammation, liver cancer and allergy, respectively). H2L5 ligand displays significant activity towards inflammation and allergy diseases. Such potential feature will give a well insight about their biological attitude in future experimentation.

Design, synthesis, and biological evaluation of 2-substituted-2,3,4,9-tetrahydrospiro-ß-carboline-3-carboxylic acid derivatives as first-in-class mast cell stabilizers.

Mast cell degranulation plays a momentous role in myriad diseases like asthma, eczema, allergic rhinitis, and conjunctivitis as well as anaphylactic shock; hence, there is an unmet need for developing new mast cells stabilizers. The reported mast cell stabilizers have a heterocyclic moiety and an acidic group. Furthermore, the role of tryptophan in suppression of mast cell activation is established. Hence, we prepared constrained analogs of tryptophan, which are derivatives of 2,3,4,9-tetrahydrospiro-ß-carboline-3-carboxylic acid, and evaluated them for ex vivo inhibition of compound 48/80-induced mast degranulation activity. By comparing IC50 (µM) values with that of the standard drug sodium cromoglycate (IC50 = 0.489 ± 0.003 µM), compounds with bulky groups like heptyl (compound 9; IC50 = 0.389 ± 0.015 µM) and octyl (compound 10; IC50 = 0.354 ± 0.023 µM) were found to be of similar potency as sodium cromoglycate. Furthermore, the polar group-containing compounds like the chloropropyl (compound 16; IC50 = 0.382 ± 0.083 µM) and benzoyl derivative (compound 14; IC50 = 00.469 ± 0.032 µM) were also found to be of similar potency as sodium cromoglycate. This is a seminal study of spiro-ß-carboline mast cell stabilization having a wider scope in mast cell research; yet, the mechanism of action remains elusive.

Development and evaluation of an oral fast disintegrating anti-allergic film using hot-melt extrusion technology.

The main objective of this novel study was to develop chlorpheniramine maleate orally disintegrating films (ODF) using hot-melt extrusion technology and evaluate the characteristics of the formulation using in vitro and in vivo methods. Modified starch with glycerol was used as a polymer matrix for melt extrusion. Sweetening and saliva-simulating agents were incorporated to improve palatability and lower the disintegration time of film formulations. A standard screw configuration was applied, and the last zone of the barrel was opened to discharge water vapors, which helped to manufacture non-sticky, clear, and uniform films. The film formulations demonstrated rapid disintegration times (6-11s) and more than 95% dissolution in 5min. In addition, the films had characteristic mechanical properties that were helpful in handling and storage. An animal model was employed to determine the taste masking of melt-extruded films. The lead film formulation was subjected to a human panel for evaluation of extent of taste masking and disintegration.

A novel compound 2-(4-{2-[(phenylthio)acetyl]carbonohydrazonoyl}phenoxy)acetamide downregulates TSLP through blocking of caspase-1/NF-κB pathways.

Thymic stromal lymphopoietin (TSLP) is regarded as the main factor responsible for the pathogenesis of allergic disorders such as atopic dermatitis, chronic obstructive pulmonary diseases, and allergic rhinitis. As part of our continuing search for novel anti-inflammatory compounds, 2-(4-{2-[(phenylthio)acetyl]carbonohydrazonoyl}phenoxy)acetamide (PA) was analyzed. In the present study, we examined how PA regulates the mRNA expression and production of TSLP in the human mast cell line, HMC-1 cells. Computer-aided docking simulation, enzyme-linked immunosorbent assay, quantitative polymerase chain reaction, caspase-1 assay, and Western blotting were used to investigate the effects of PA. PA decreased the mRNA expression and production of TSLP in HMC-1 cells. PA (1µM) inhibited the TSLP production up to 87.710±5.201%. PA also improved the activation and phosphorylation of nuclear factor-κB as well as the degradation and phosphorylation of IκBα. Caspase-1 activation was up-regulated in activated HMC-1 cells, whereas caspase-1 activation was down-regulated by PA. Finally, PA inhibited ear swelling response induced by phorbol myristate acetate in mice. These results indicate that PA would be effective to treat inflammatory and atopic disorders through the down-regulations of TSLP.

The isolation and synthesis of a novel benzofuran compound from Tephrosia purpurea, and the synthesis of several related derivatives, which suppress histamine H1 receptor gene expression.

A novel naturally occurring compound with a benzofuran skeleton was isolated from a plant, Tephrosia purpurea collected in Bangladesh. The chemical synthesis of this compound confirmed its structure, and preliminary biological results showed its suppressive activity towards histamine H1 gene expression. One isomer and four derivatives were also synthesized, and their suppression activity was investigated. Although only small quantities of this compound can be isolated from its natural source, a 10 g scale synthesis was demonstrated by the newly developed method.

Novel binuclear µ-oxo diruthenium complexes combined with ibuprofen and ketoprofen: Interaction with relevant target biomolecules and anti-allergic potential.

This work presents the synthesis and characterization of two novel binuclear ruthenium compounds of general formula [Ru2O(carb)2(py)6](PF6)2, where py=pyridine and carb are the non-steroidal anti-inflammatory drugs ibuprofen (1) and ketoprofen (2). Both complexes were characterized by ESI-MS/MS spectrometry. The fragmentation patterns, which confirm the proposed structures, are presented. Besides that, compounds 1 and 2 present the charge transfer transitions within 325-330nm; and the intra-core transitions around 585nm, which is the typical spectra profile for [Ru2O] analogues. This suggests the carboxylate bridge has little influence in their electronic structure. The effects of the diruthenium complexes on Ig-E mediated mast cell activation were evaluated by measuring the enzyme ß-hexosaminidase released by mast cells stimulated by antigen. The inhibitory potential of the ketoprofen complex against mast cell stimulation suggests its promising application as a therapeutic agent for treating or preventing IgE-mediated allergic diseases. In addition, in vitro metabolism assays had shown that the ibuprofen complex is metabolized by the cytochrome P450 enzymes.

Identification and Characterization of a Novel IL-4 Receptor α Chain (IL-4Rα) Antagonist to Inhibit IL-4 Signalling.

BACKGROUND/AIMS: In recent times, allergy has become a financial, physical and psychological burden to the society as a whole. In allergic cascades, cytokine IL-4 binds to IL-4 receptor (IL-4R), consequently producing allergen-specific IgE antibodies by B cells. In addition, among other functions, IL-4 is also responsible for B and T cell proliferation and differentiation. Hence, characterization of novel antagonists that inhibit IL-4 signalling forms the overall aim of this study. METHODS: Phage display was used to screen a random 12-mer synthetic peptide library with a human IL-4Rα to identify peptide candidates. Once identified, the peptides were commercially synthesized and used for in vitro immunoassays. RESULTS: We have successfully used phage display to identify M13 phage clones that demonstrated specific binding to IL-4Rα. The peptide N1 was synthesized for use in ELISA, demonstrating significant binding to IL-4Rα and inhibiting interaction with cytokine IL-4. Furthermore, the peptide was tested in a transfected HEK-Blue IL-4 reporter cell line model, which produces alkaline phosphatase (AP). QUANTI-Blue, a substrate, breaks down in the presence of AP producing a blue coloration. Using this colorimetric analysis, >50% inhibition of IL-4 signalling was achieved. CONCLUSION: We have successfully identified and characterised a synthetic peptide antagonist against IL-4Rα, which effectively inhibits IL-4 interaction with the IL-4Rα in vitro. Since IL-4 interaction with IL-4Rα is a common pathway for many allergies, a prophylactic treatment can be devised by inhibiting this interaction for future treatment of allergies.

Total synthesis and biological evaluation of the natural product (-)-cyclonerodiol, a new inhibitor of IL-4 signaling.

In a screening program of natural compounds from fungi, the known cyclopentanoid sesquiterpene (-)-cyclonerodiol was identified as a specific inhibitor of the IL-4 induced STAT6 signaling pathway (IC50 = 9.7 µM) which is required for the differentiation of naive CD4 T cells to T helper type 2 (Th2) lymphocytes. As many allergic conditions, including allergic asthma and atopic diseases, are driven by an excessive Th2 response, STAT6 is a promising target for the development of new therapeutics. The compound was synthesized in six steps from (-)-linalool using an epoxide radical cyclization as the key step.

Synthesis of glycosides of resveratrol, pterostilbene, and piceatannol, and their anti-oxidant, anti-allergic, and neuroprotective activities.

Resveratrol was glucosylated to its 3- and 4'-ß-glucosides by cultured cells of Phytolacca americana. On the other hand, cultured P. americana cells glucosylated pterostilbene to its 4'-ß-glucoside. P. americana cells converted piceatannol into its 4'-ß-glucoside. The 3- and 4'-ß-glucosides of resveratrol were further glucosylated to 3- and 4'-ß-maltosides of resveratrol, 4'-ß-maltoside of which is a new compound, by cyclodextrin glucanotransferase. Resveratrol 3-ß-glucoside and 3-ß-maltoside showed low 2,2-diphenyl-1-picrylhydrazyl free-radical-scavenging activity, whereas other glucosides had no radical-scavenging activity. Piceatannol 4'-ß-glucoside showed the strongest inhibitory activity among the stilbene glycosides towards histamine release from rat peritoneal mast cells. Pterostilbene 4'-ß-glucoside showed high phosphodiesterase inhibitory activity.

Design, synthesis, and inhibitory activity of potent, photoswitchable mast cell activation inhibitors.

Allergic reactions affect millions of people worldwide. The need for new and effective antiallergic agents is evident, and insight into the underlying mechanisms that lead to allergic events is necessary. Herein, we report the design, synthesis, and activity of photoswitchable mast cell activation inhibitors. In mast cell degranulation assays, these inhibitors possess significantly greater potency than an original, chromone-based antiallergic agent. Furthermore, one of the photoswitchable inhibitors shows a significant difference in inhibitory activity between its two photoisomeric forms. Further optimization could ultimately lead to a photoswitchable compound suitable for studying mechanisms involved in allergic reactions in a novel manner, with activity addressable by light and with precise spatiotemporal control over events at the molecular level.

Syntheses and anti-allergic activity of 2-((bis(trimethylsilyl)methylthio/methylsulfonyl)methyl)-5-aryl-1,3,4-oxadiazoles.

A new class of sila-substituted 1,3,4-oxadiazoles was synthesized by a convenient synthetic method. Both silathio/silasulfonyl acetic acids were efficiently condensed with benzohydrazides in the presence of phosphorus oxychloride to give sila-substituted 1,3,4-oxadiazoles in high yields. The compounds displayed variable extent of anti-allergic activity on IgE/Ag-stimulated RBL-2H3 cells at 50 and 100 µM concentrations. Compounds having sulfonyl moiety with bis(trimethylsilyl)-1,3,4-oxadiazoles (5a-c), exhibited better anti-allergic activities than those of compounds having sulphur moiety with bis(trimethylsilyl)-1,3,4-oxadiazoles (4a-c).

Investigation of the binding pocket of human hematopoietic prostaglandin (PG) D2 synthase (hH-PGDS): a tale of two waters.

The inhibition of hH-PGDS has been proposed as a potential target for the development of anti-allergic and anti-inflammatory drugs. Herein we describe our investigation of the binding pocket of this important enzyme and our observation that two water molecules bind to our inhibitors and the enzyme. A series of compounds were prepared to the probe the importance of the water molecules in determining the binding affinity of the inhibitors to the enzyme. The study provides insight into the binding requirements for the design of potent hH-PGDS inhibitors.