Distinct effects of imperatorin on allergic rhinitis: imperatorin inhibits caspase-1 activity in vivo and in vitro

The potential application and molecular mechanisms of natural products in the treatment of allergic rhinitis: A review

BACKGROUNDS

Allergic rhinitis (AR) is a non-infectious chronic inflammation of the nasal mucosa mainly mediated by immunoglobulin E (IgE) in atopic individuals after exposure to allergens. The application of AR guideline-recommended pharmacotherapies can rapidly relieve symptoms of AR but with poor long-term efficacy, and many of these therapies have side effects. Many natural products and their derivatives have shown potential therapeutic effects on AR with fewer side effects.

OBJECTIVES

This review aims to expand understanding of the roles and mechanisms of natural compounds in the treatment of AR and to highlight the importance of utilizing natural products in the treatment of AR.

MATERIAL AND METHOD

We conducted a systematic literature search using PubMed, Web of Science, Google Scholar, and Clinical Trials. The search was performed using keywords including natural products, natural compounds, bioproducts, plant extracts, naturally derived products, natural resources, allergic rhinitis, hay fever, pollinosis, nasal allergy. Comprehensive research and compilation of existing literature were conducted.

RESULTS

This article provided a comprehensive review of the potential therapeutic effects and mechanisms of natural compounds in the treatment of AR. We emphasized that natural products primarily exert their effects by modulating signalling pathways such as NF-κB, MAPKs, STAT3/ROR-γt/Foxp3, and GATA3/T-bet, thereby inhibiting the activation and expansion of allergic inflammation. We also discussed their toxicity and clinical applications in AR therapy.

CONCLUSION

Taken together, natural products exhibit great potential in the treatment of AR. This review is also expected to facilitate the application of natural products as candidates for treating AR. Furthermore, drug discovery based on natural products has a promising prospect in AR treatment.

Ameliorative Effect of Imperatorin on Dermatophagoides pteronyssinus-Induced Allergic Asthma by Suppressing the Th2 Response in Mice

Imperatorin is a furanocoumarin derivative and an effective ingredient in several Chinese medicinal herbs. It has favorable expectorant, analgesic, and anti-inflammatory effects. In this study, we investigated whether imperatorin has protective effects against Dermatophagoides pteronyssinus (Der p)-induced asthma in mice. Lung and bronchial tissues were histopathologically examined through hematoxylin–eosin staining. The concentrations of immunoglobin E (IgE), IgG1, IgG2a in serum and those of T helper 1 (Th1) and two cytokines and eosinophil-activated chemokines in bronchoalveolar lavage fluid (BALF) were detected using an enzyme immunoassay. Histological examination revealed that imperatorin reduced inflammatory cell infiltration, mucus hypersecretion, and endothelial cell hyperplasia. The examination also indicated that imperatorin could reduce the inflammatory cell count in BALF as well as IgE and IgG1 expression in serum, but IgG2a expression was significantly increased. Imperatorin reduced the production of interleukin (IL)-4, IL-5, and IL-13 by Th2, promoted the production of interferon-γ and IL-12 by Th1, and increased the production of IL-10 in bronchoalveolar lavage fluid. These findings suggest that imperatorin has a considerable anti-inflammatory effect on Der p-induced allergic asthma in mice.

Imperatorin alleviated NLR family pyrin domain-containing 3 inflammasome cascade-induced synovial fibrosis and synovitis in rats with knee osteoarthritis

We aimed to clarify the therapeutic effects of imperatorin (IMP) on knee osteoarthritis (KOA). Thirty 3-month-old SD male rats were randomly divided into Normal, monosodium iodoacetate (MIA) and MIA+IMP groups. Their synovial tissues were subjected to histopathological analysis. Primary synovial fibroblasts obtained from additional normal rats were treated by lipopolysaccharide (LPS) and then IMP. The mRNA and protein expressions of factors related to synovitis and synovial fibrosis were detected by qRT-PCR and Western blotting, respectively. The concentrations of inflammatory factors IL-1β and IL-18 were measured by ELISA. IMP reduced HIF-1α, NLR family pyrin domain-containing 3 inflammasome expression and IL-1β, IL-18 production in synovial fibroblasts induced by LPS. IMP also downregulated synovial fibrosis markers. In vitro study revealed that MIA-induced synovitis and synovial fibrosis were relieved by IMP. IMP relieves the inflammation associated with synovitis and synovial fibrosis. It reduces the production of pro-inflammatory mediators and cytokines and inhibits TGF-β1, TIMP-1 and VEGF expressions that promote synovial fibrosis.

Imperatorin Alleviates Psoriasiform Dermatitis by Blocking Neutrophil Respiratory Burst, Adhesion, and Chemotaxis Through Selective Phosphodiesterase 4 Inhibition

Aim: Neutrophil infiltration and increased oxidative stress are involved in the pathogenesis and severity of psoriasis. Although the therapy of psoriasis remains elusive, targeting treatment to reduce oxidative stress is considered a potential option. Our study demonstrates the anti-inflammatory effects of a natural furocoumarin, imperatorin, on activated human neutrophils and psoriasiform dermatitis in mice. Results: Imperatorin inhibited superoxide anion generation, neutrophil adhesion, and migration in N-formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLF)-stimulated human neutrophils. Further studies showed that imperatorin induced a decrease in cAMP-specific phosphodiesterase (PDE) activity, and increased intracellular cAMP levels and protein kinase A (PKA) activity in human neutrophils. The enzyme activities of PDE4 subtypes, but not PDE3 and PDE7, were inhibited by imperatorin. Furthermore, imperatorin inhibited the phosphorylation of protein kinase B (Akt), extracellular regulated kinase (ERK), and c-Jun N-terminal kinase (JNK), as well as Ca²⁺ mobilization in fMLF-stimulated neutrophils. These suppressive effects of imperatorin on cell responses and signaling were reversed by PKA inhibitor, suggesting that cAMP/PKA is involved in the anti-inflammatory effects of imperatorin. In vivo studies of imiquimod- and interleukin-23-induced mouse psoriasiform dermatitis demonstrated that imperatorin alleviated skin desquamation, epidermal thickening, keratinocyte hyperproliferation, and neutrophil infiltration. Innovation and Conclusion: Our results demonstrate that imperatorin inhibits human neutrophil respiratory burst, adhesion, and migration through the elevation of cAMP/PKA to inhibit Akt, ERK, JNK, and Ca²⁺ mobilization. Imperatorin is a natural inhibitor of PDE4A/B/C and may serve as a lead for developing new therapeutics to treat neutrophilic psoriasis. Antioxid. Redox Signal. 35, 885-903.

Dietary Intake of Coumarins and Furocoumarins through Citrus Beverages: A Detailed Estimation by a HPLC-MS/MS Method Combined with the Linear Retention Index System

Official regulations concerning the maximum number of substances in food are introduced as a consequence of possible adverse effects, after oral administration. In this regard, analytical methods are necessary in order to determine specific targets. Among oxygen heterocyclic compounds (OHCs, that are furocoumarins, coumarins and polymethoxyflavones), only coumarin is subject to restriction by the Regulation (EC) No 1334/2008 of the European Parliament. Furocoumarins are known for their phototoxicity and other side effects due to their dietary intake; however, an official limit about the maximum content of these compounds in food is still missing. The lack of information about the real amount of these compounds in food is responsible for the conflicting opinions about the introduction of an official limit. The HPLC-MS/MS method here proposed, in combination with the linear retention index system, represents an innovative analytical strategy for the characterization of OHCs in citrus beverages. Several types of drinks were analysed in order to quantify 35 OHCs in total. This method is suitable for the quality control of OHCs in food and the obtained results may be considered as informative data useful for the regulatory authorities in the emission of new opinions and for a potential new regulation in this field.

Imperatorin Relieved Ulcerative Colitis by Regulating the Nrf-2/ARE/HO-1 Pathway in Rats

Ulcerative colitis is a common intestinal inflammatory disease. Imperatorin (IMP) has been reported to alleviate mast cell-mediated allergic responses by suppressing the expression of Nrf-2, ARE, and HO-1. However, whether IMP can relieve ulcerative colitis by regulating Nrf-2/ARE/HO-1 pathway is unclear. Thus, this study aims to investigate the effect of IMP on ulcerative colitis in rats and elucidate the potential mechanism. In our study, rats were treated with 2,4,6-trinitro-benzenesulfonic acid (TNBS) to induce the animal model of ulcerative colitis. Next, these rats were treated with diverse doses of IMP (15 mg/kg, 30 mg/kg, and 60 mg/kg) and sacrificed at different time points (3 days, 7 days, and 14 days). The levels of inflammatory factors (TNF-α and IL-6) in colon tissues were detected with ELISA kits. H&E staining was performed to observe the pathologic changes of the colon tissues. The expression of Nrf-2, ARE, and HO-1 in colon tissues was determined with the immunofluorescence and Western blotting. The results showed that application of IMP alleviated the symptoms of ulcerative colitis and inhibited the secretion of TNF-α and IL-6. Besides, treatment of IMP promoted the expression of Nrf-2, ARE, and HO-1 in the early stage of this disease (the third day), but suppressed the expression of Nrf-2, ARE, and HO-1 in the advanced stage of the ulcerative colitis (the fourteenth day). Collectively, IMP relieved the symptoms of ulcerative colitis by regulating the Nrf-2/ARE/HO-1 pathway, which might provide a new therapeutic drug to support the clinical treatment of ulcerative colitis.

In vivo and in vitro anti‑allergic and anti‑inflammatory effects of Dryopteris crassirhizoma through the modulation of the NF‑ĸB signaling pathway in an ovalbumin‑induced allergic asthma mouse model

Dryopteris crassirhizoma (DC) has a wide range of pharmacological effects, including antibacterial, anti-influenza virus, anti-tumor, anti-reverse transcriptase and antioxidant effects. However, the inhibitory effect of DC on allergic inflammatory response remains unclear; therefore, the current study used an experimental ovalbumin (OVA)-induced allergic asthma mouse model and phorbol myristate acetate (PMA)- and A23187-stimulated HMC-1 cells to reveal the effects of DC in regulating airway inflammation and its possible mechanism. Allergic asthma was initiated in BALB/c mice via exposure to OVA emulsified in aluminum, on days 1 and 14. Thereafter, the mice were treated with DC or dexamethasone (Dex) orally, before being challenged, from days 15 to 26. Subsequently, the mice were challenged with OVA on days 27, 28 and 29. The results of histological analysis indicated that the administration of DC decreased the number of inflammatory cells in the bronchoalveolar lavage fluid (BALF) and suppressed eosinophilic infiltration, mucus production and collagen deposition in the lung tissue. DC treatment increased the level of T helper type 1 (Th1) cytokines (IL-10 and interferon (IFN)-γ) and decreased the levels Th2 cytokines (IL-4, IL-5 and IL-13) and proinflammatory cytokines (IL-6 and TNF-α). Furthermore, DC treatment inhibited the activation of NF-κB signaling (NF-κB, p-NF-κB, IκB and p-IκB), both in BALF and lung homogenates. Serum levels of total IgE and OVA-specific IgE and IgG1 were significantly lower after DC treatment compared with after OVA treatment. However, the anti-inflammatory effect of OVA-specific IgG2a was higher after DC treatment. In addition, DC treatment attenuated the production of proinflammatory cytokines, including IL-6 and TNF-α, and the activation of NF-κB signaling (NF-κB and p-NF-κB), in PMA and calcium ionophore A23187-stimulated HMC-1 cells. In summary, the current study demonstrated that DC acts a potent anti-allergic and anti-inflammatory drug by modulating the Th1 and Th2 response and reducing the allergic inflammatory reaction in PMA and A23187-stimulated HMC-1 cells via NF-κB signaling in an OVA-induced allergic asthma model.

Imperatorin and β-sitosterol have synergistic activities in alleviating collagen-induced arthritis

Rheumatoid arthritis (RA) is a chronic disease with complex molecular network of pathophysiology, single drug is usually not full satisfactory because it is almost impossible to target the whole molecular network of the disease. Drug combinations that act synergistically with each another is an effective strategy in RA therapy. In this study, we aimed to establish a new strategy to search effective synergized compounds from Chinese herbal medicine (CHM) used in RA. Based on multi‐information integrative approaches, imperatorin (IMP) and β‐sitosterol (STO) were predicted as the most effective pair for RA therapy. Further animal experiments demonstrated that IMP+STO treatment ameliorated arthritis severity of collagen‐induced arthritis (CIA) rats in a synergistic manner, whereas IMP or STO administration separately had no such effect. RNA sequencing and IPA analysis revealed that the synergistic mechanism of IMP+STO treatment was related to its regulatory effect on 5 canonical signaling pathways, which were not found when IMP or STO used alone. Moreover, LTA, CD83, and SREBF1 were 3 important targets for synergistic mechanism of IMP+STO treatment. The levels of these 3 genes were significantly up‐regulated in IMP+STO group compared to model group, whereas IMP or STO administration separately had no effect on them. In conclusion, this study found that IMP and STO were 2 synergistic compounds from the CHM in RA therapy, whose synergistic mechanism was closely related to regulate the levels of LTA, CD83, and SREBF1.

Imperatorin: A review of its pharmacology, toxicity and pharmacokinetics

As a naturally occurring furanocoumarin, the medicinal value of imperatorin has been studied more and more. We hope to provide useful information for the further development of imperatorin by analyzing the literature of imperatorin in recent years. By collating the literature on the pharmacology of imperatorin, we found that the pharmacological activity of imperatorin is wide and imperatorin can be used for anti-cancer, neuroprotection, anti-inflammatory, anti-hypertension and antibacterial. In addition, we found that some researchers confirmed the toxicity of imperatorin. Pharmacokinetic studies demonstrated that oxidation metabolism is the main metabolic pathways of imperatorin. At present, the shortcomings of research on imperatorin mainly include: most pharmacological studies are concentrated in vitro, lacking enough in vivo experimental data; more and more studies showed that imperatorin has synergistic effect with other drugs in anticancer and other aspects, but lacking the detailed explanation of the mechanism of the synergistic effect; imperatorin has side effect, but it lacks enough experimental conclusions. Based on the above defects, we believe that more in vivo experiments of imperatorin should be carried out in the future; future research need to explore synergistic mechanisms of imperatorin with other drugs, especially in anticancer; the dose affects both the pharmacological activity and the side effect of imperatorin. The relationship between the dose and the two aspects need to be further studied in order to reduce the side effect. In addition, through structural modification of imperatorin, it is possible to improve the treatment effect and reduce side effect.

Effects of imperatorin in the cardiovascular system and cancer

Patients with cancer survivors are at increased risk of cardiovascular disease(CVD). Cardio-oncology has developed as a new discipline with the advances in cancer treatment. There are many new challenges for the clinician and a new frontier for research and investigation. There is an urgent need for further study on the prevention of cardiovascular toxicity. Imperatorin (IMP) is a natural form of coumarin and extract from several plants with diver's pharmacokinetic effects, including antioxidant and anti-inflammatory properties. This review focus on the molecular mechanisms and pharmacological effects of Imperatorin maybe provide potential cancer and cardiovascular protection that targets IMP. Further studies are required to elucidate the entire spectrum of cytotoxic activities of these compounds to validate and expand their preclinical and clinical applications and to clarify the potential role of IMP.

Potential anti-inflammatory effect of Madi-Ryuk and its active ingredient tannic acid on allergic rhinitis

Madi-Ryuk (MDR) is a traditional Korean medicine and it has been widely used in Korea to treat arthritis and we previously reported the anti-allergic inflammatory effect of MDR in vitro model. However, therapeutic evidence of MDR on in vivo model of allergic inflammatory reaction has not yet been demonstrated. The research purpose was to investigate the efficacy of MDR and its active ingredient tannic acid (TA) in ovalbumin (OVA)-induced AR mice model. OVA-challenged AR mice orally medicated MDR or its active ingredient TA daily for ten days. In mice having a AR, MDR and TA prominently diminished number of rubs and levels of histamine, IgE, thymic stromal lymphopoietin, interleukin (IL)-1β, IL-4, IL-5, IL-13, IL-33, and tumor necrosis factor-α. In addition, protein expression levels and activities of caspase-1 were declined by oral medication of MDR and TA. Decline in levels of macrophage inflammatory protein-2 and intercellular adhesion molecules-1 and reduction in penetrations of inflammatory cells into inflamed tissue were also noted in MDR and TA groups. Taken together, identification of MDR effect in preclinical models suggests that MDR may be a therapeutic drug for the treatment and prevention of AR.

Anti-inflammatory Property of Imperatorin on Alveolar Macrophages and Inflammatory Lung Injury

Imperatorin is one of the furanocoumarin derivatives and exists in many medicinal herbs with anticancer, antiviral, antibacterial, and antihypertensive activities. In this study, we examined the anti-inflammatory effects of imperatorin on inflammation-associated lung diseases. Imperatorin reduced iNOS and COX-2 expression and also IL-6 and TNFα production enhanced by zymosan. Imperatorin also inhibited the signaling pathways of JAK/STAT and NF-κB. Moreover, in vivo study also revealed that zymosan-induced immune cell infiltration, pulmonary fibrosis, and edema were relieved by imperatorin in mice. We found that imperatorin exerts anti-inflammatory effects that are associated with amelioration of lung inflammation, edema, and rapid fibrosis. Studies on alveolar macrophages also reveal that imperatorin reduced the production of pro-inflammatory mediators and cytokines and inhibited pro-inflammatory JAK1/STAT3 and NF-κB signaling pathways. These results indicate that imperatorin may be a potential anti-inflammatory agent for inflammatory-associated lung diseases.

Biomolecular Targets of Oxyprenylated Phenylpropanoids and Polyketides

Oxyprenylated secondary metabolites (e.g. phenylpropanoids and polyketides) represent a rare class of natural compounds. Over the past two decades, this group of phytochemicals has become a topic of intense research activity by several teams worldwide due to their in vitro and in vivo pharmacological activities, and to their great therapeutic and nutraceutical potential for the chemoprevention of acute and chronic diseases affecting humans. Such investigations have provided evidence that oxyprenylated secondary metabolites are able to interact with several biological targets at different levels accounting for their observed anticarcinogenic, anti-inflammatory, neuroprotective, immunomodulatory, antihypertensive, and metabolic effects. The aim of the present contribution is to provide a detailed survey of the so far reported data on the capacities of selected oxyprenylated phenylpropanoids and polyketides to trigger receptors, enzymes, and other types of cellular factors for which they exhibit a high degree of affinity and therefore evoke specific responses. With respect to the rather small amounts of these compounds available from natural sources, their chemical synthesis is also highlighted.

Blood-to-Retina Transport of Imperatorin Involves the Carrier-Mediated Transporter System at the Inner Blood-Retinal Barrier

This study investigated the mechanism of transporting imperatorin across the inner blood-retinal barrier (iBRB). The carotid artery single injection method was used to calculate the retinal uptake index (RUI) of [³H]imperatorin in vivo, whereas the retinal capillary endothelial cell lines were used for the in vitro uptake and mRNA expression assays. RUI value of [³H]imperatorin was greater than that of the reference compound ([¹⁴C]n-butanol). [³H]Imperatorin significantly reduced the RUI in the presence of neuroprotective organic cationic drugs at 10 mM. However, tetraethylammonium and p-aminohippuric acid showed no significant effects. [³H]Imperatorin uptake by TR-iBRB2 cells was time-, pH-, energy-, and concentration-dependent with a K_m value of 679 ± 130 μM. In addition, the uptake study showed insensitivity to sodium and membrane potential. Various organic cations including pyrilamine, nicotine, and clonidine significantly reduced the uptake of [³H]imperatorin, whereas organic anions and monocarboxylic acids did not. Furthermore, the mRNA expression level dropped markedly with rOCTN1, rOCTN2, rPMAT, and rMATE1 small interfering RNAs in the transfection study. Moreover, [³H]imperatorin uptake remained neutral with small interfering RNA transfections. Our results indicate that imperatorin transport across the iBRB involves carrier-mediated transporter system.

NLRP3 inflammasome: A likely target for the treatment of allergic diseases

Allergic diseases, such as asthma, rhinitis, dermatitis, conjunctivitis, and anaphylaxis, have recently become a global public health concern. According to previous studies, the NLRP3 inflammasome is a multi-protein complex known to be associated with many inflammatory conditions. In response to allergens or allergen/damage-associated molecular signals, NLRP3 changes its conformation to allow the assembly of the NLRP3 inflammasome complex and activates caspase-1, which is an evolutionarily conserved enzyme that proteolytically cleaves other proteins, such as the precursors of the inflammatory cytokines IL-1β and IL-18. Subsequently, active caspase-1 cleaves pro-IL-1 and pro-IL-18. Recently, accumulating human and mouse experimental evidence has demonstrated that the NLRP3 inflammasome, IL-1β, and IL-18 are critically involved in the development of allergic diseases. Furthermore, the application of specific NLRP3 inflammasome inhibitors has been demonstrated in animal models. Therefore, these inhibitors may represent potential therapeutic methods for the management of clinical allergic disorders. This review summarizes findings related to the NLRP3 inflammasome and its related factors and concludes that specific NLRP3 inflammasome inhibitors may be potential therapeutic agents for allergic diseases.

Biyuanling suppresses the toluene-2, 4-diisocyanate induced allergic rhinitis in guinea pigs

Allergic rhinitis (AR), one of the common diseases of the upper respiratory system, is associated with high risk of nasopharyngeal carcinoma. Biyuanling Granules (BLG), a formulated preparation of traditional Chinese medicine, has been used in China for treatment of AR for more than a decade; however, its exact action against allergic rhinitis and the mechanism involved remain unclear. In this study, we studied the effects of BLG on allergic rhinitis induced by toluene-2, 4- diisocyanate (TDI) in guinea pigs. The anti-AR effects of BLG were evaluated by behavior observations, histological examinations of the nasal tissues stained with hematoxylin and eosin staining (H&E), immunohistochemical analyses of pulmonary surfactant associated protein (SP), Bcl-2 Associated X Protei (Bax), tumor necrosis factor (TNF-α) and vascular cell adhesion molecule-1 (VCAM-1) in the nasal mucosa, and serum tests of interleukin-4 (IL-4) and human SARS-specific immunoglobulin (SIgE) levels. We observed that in the AR-positive animals treated with BLG, the symptom scores were significantly higher (P < 0.01), the nasal mucosa edemas and inflammatory infiltrates were significantly alleviated (P < 0.01) and the serum IL-4 and SIgE levels were significantly decreased (P < 0.05) as compared with the control group. Immunohistochemical examinations of the nasal mucosa demonstrated that the expressions of TNF-α, SP and VCAM-1 were significantly decreased (P < 0.01), whereas Bax expression was increased in the BLG treatment groups (P < 0.05). These results indicate that BLG can effectively suppress the TDI-induced AR, and that the protective effects of BLG were associated with reductions of TNF-α, SP and VCAM-1, and an elevation of Bax, suggesting that BLG exerts its AR-suppressive effects through inhibition of inflammatory response.

Xinqin exhibits the anti-allergic effect through the JAK2/STAT5 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Xinqin, a polyherbal medicine, is an important traditional Chinese herbal formula used in traditional oriental medicine for treatment of allergic rhinitis (AR). The formula is based on the Chinese Pharmacopoeia AIM OF THE STUDY: Previously, Xinqin exhibited potent anti-allergic effect in a guinea pig model of AR. In this study, we explored the molecular mechanism of the anti-allergic effect mediated by Xinqin.

MATERIALS AND METHODS

AR was induced in guinea pigs (Hartley) with toluene-2, 4-diisocyanate (TDI) in vivo and in HMC-1 mast cells with A23187/phorbol 12-myristate-13-acetate (PMA) in vitro. The releases of allergic inflammatory mediators such as histamine, leukotriene (LT) D4, immunoglobulin (Ig) E, TNF-α, and IL-6 were analyzed for allergy. The mast cell degranulation was displayed in HMC-1 mast cells. The activities of janus protein kinase 2 (JAK2), signal transduction and activator of transcription 5 (STAT5) and suppressor of cytokine signaling 3 (SOCS3) were evaluated by Western blot.

RESULTS

Treatment with Xinqin resulted in AR symptoms and decreases in levels of histamine, LTD4, IgE, TNF-α, and IL-6 in serum of guinea pig model of AR and in A23187/PMA-stimulated HMC-1 mast cells. Treatment with Xinqin also inhibited cell degranulation in A23187/PMA-stimulated HMC-1 mast cells. The JAK2/STAT5 signaling pathway could play an important role in the anti-allergic activity mediated by Xinqin.

CONCLUSIONS

Xinqin exerts the anti-allergic effect by modulating mast cell-mediated allergic responses by down-regulating JAK2/STAT5 signaling pathway. Results from this study provide a mechanistic basis for the application of Xinqin in the treatment of AR.

Natural and Synthetic Coumarins with Effects on Inflammation

In this review, we will present the different aspects of coumarins and derivatives, from natural origins or synthetically prepared, and their action on inflammation. Coumarins and also furo- and pyranocoumarins are found in many different plants. These compounds are very often investigated for antioxidant properties. Other biological properties are also possible and anti-inflammation activity is one of these. As coumarins are also available quite easily via synthesis, natural ones can be prepared this way but derivatives with special substituents are also feasible. A review on the same topic appeared in 2004 and our contribution will take into account everything published since then.

Inhibitory effect of baicalin on allergic response in ovalbumin-induced allergic rhinitis guinea pigs and lipopolysaccharide-stimulated human mast cells

OBJECTIVE

Baicalin, a flavonoid compound purified from the dry roots of Scutellaria baicalensis Georgi, has generally been used for the treatment of various allergic diseases. However, there is little information about the anti-inflammatory effects of baicalin for allergic rhinitis. This study aims to investigate the anti-allergic effect of baicalin on allergic response in ovalbumin (OVA)-induced allergic rhinitis guinea pigs and lipopolysaccharide (LPS)-stimulated human mast cells.

METHODS

Using in vivo models, we evaluated the effect of baicalin on allergic rhinitis symptoms via recording the number of nasal rubs and sneezes. The levels of histamine, OVA-specific immunoglobulin E(IgE), eosinophil cationic protein (ECP) and inflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA). The histological changes of nasal mucosa were observed by light microscope after HE staining. In vitro, the release of histamine and β-hexosaminidase of compound 48/80-induced human mast cells were measured by ELISA and PNP-NAG colorimetry, respectively. The productions of inflammatory cytokines of LPS-stimulated human mast cells were determined using ELISA. Western blot was used to test the protein expression of JAK2, p-JAK2, STAT5, p-STAT5, IKKβ, p-IKKβ, IκBα, p-IκBα and NF-κB (p65) of LPS-stimulated human mast cells.

RESULTS

The oral administration of baicalin at doses of 50 and 200 mg/kg improved allergic rhinitis symptoms and the histological changes of nasal mucosa and decreased the serum levels of histamine, ECP, interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α and OVA-specific IgE in OVA-induced allergic rhinitis guinea pigs. In vitro, baicalin suppressed the release of histamine and β-hexosaminidase in compound 48/80-induced human mast cells. In addition, baicalin also inhibited the productions of inflammatory cytokines such as IL-1β, IL-6, IL-8 and TNF-α and suppressed the phosphorylation of JAK2, STAT5, IKKβ, IκBα and the nuclear translocation of NF-κB (p65) subunit in LPS-stimulated human mast cells.

CONCLUSIONS

These results suggest that baicalin can effectively prevent allergic response in OVA-induced allergic rhinitis guinea pigs and inhibit inflammatory response via blocking JAK2-STAT5 and NF-κB signaling pathways in LPS-stimulated human mast cells. Considered together,the results show that baicalin may be a useful drug in the treatment of allergic rhinitis.

Protective effects of rutin through regulation of vascular endothelial growth factor in allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is an allergic inflammatory disease induced by various mediators released by infiltrating inflammatory cells. Vascular endothelial growth factor (VEGF) increases the airway inflammatory response by promoting vascular permeability. Furthermore, it is known that Allium hookeri and one of its constituent compounds, rutin (RU), have anti-inflammatory, antioxidant, and antiplatelet effects.

OBJECTIVE

The aim of this study was to evaluate the regulation of AR by RU and A. hookeri.

METHODS

We assessed the therapeutic effects and the regulatory mechanisms of A. hookeri and RU on phorbol 12-myristate 13-acetate plus A23187 (PMACI) stimulated human mast cell line (HMC) 1 cells, and ovalbumin (OVA) sensitized mouse model of AR.

RESULTS

A. hookeri and RU significantly inhibited the production and messenger RNA (mRNA) expression of VEGF in PMACI-stimulated HMC-1 cells and significantly decreased VEGF levels in our murine AR model. The increased rubs scores and immunoglobulin E and interleukin (IL) 4 levels in OVA-sensitized mice were significantly reduced by the administration of A. hookeri, and RU significantly inhibited the production and mRNA expression and RU. Also, A. hookeri and RU significantly reduced IL-4 and IL-5 production in OVA-stimulated splenocytes. Furthermore, A. hookeri and RU significantly decreased chemokine levels (intercellular adhesion molecule-1, macrophage inflammatory protein-2) in nasal mucosa tissues. In the mouse AR model, A. hookeri and RU significantly prevented eosinophil and mast cell infiltration and reduced inflammatory cytokine levels induced by OVA sensitization. In addition, A. hookeri and RU significantly reduced mast cell-derived caspase-1 activity in OVA-sensitized mice.

CONCLUSION

The present study showed that A. hookeri or RU had an anti-allergic inflammatory effects. Analysis of these results indicated that A. hookeri and RU might protect against AR.

Imperatorin Suppresses Degranulation and Eicosanoid Generation in Activated Bone Marrow-Derived Mast Cells

Imperatorin has been known to exert many biological functions including anti-inflammatory activity. In this study, we investigated the inhibitory effects of imperatorin on the production of inflammatory mediators in mouse bone marrow-derived mast cells (BMMC). Imperatorin inhibited degranulation and the generation of eicosanoids (leukotriene C4 (LTC4) and prostaglandin D2 (PGD2)) in IgE/antigen (Ag)-stimulated BMMC. To elucidate the molecular mechanism involved in this process, we investigated the effect of imperatorin on intracellular signaling in BMMC. Biochemical analyses of the IgE/Ag-mediated signaling pathway demonstrated that imperatorin dramatically attenuated degranulation and the production of 5-lipoxygenase-dependent LTC4 and cyclooxygenase-2-dependent PGD2 through the inhibition of intracellular calcium influx/phospholipase Cγ1, cytosolic phospholipase A2/mitogen-activated protein kinases and/or nuclear factor-κB pathways in BMMC. These results suggest that the effects of imperatorin on inhibition of degranulation and eicosanoid generation through the suppression of multiple steps of IgE/Ag-mediated signaling pathways would be beneficial for the prevention of allergic inflammation.

Anti-allergic effect of a Korean traditional medicine, Biyeom-Tang on mast cells and allergic rhinitis

Background

Biyeom-Tang, a medicine prescribed by oriental clinics, has been used for the treatment of the allergic rhinitis (AR). In the present study, an ethanol extract of Biyeom-Tang (EBT) was investigated for anti-allergic properties on bone-marrow derived mast cells (BMMC) and in vivo models.

Methods

The anti-allergic properties of EBT were evaluated by measuring β-Hex release and the production of prostaglandin D₂ (PGD₂) and leukotriene C₄ (LTC₄) on BMMC in vitro and PCA and OVA-induced AR models in vivo.

Results

EBT strongly inhibited a degranulation reaction in a dose dependent manner with an IC₅₀ value of 35.6 μg/ml. In addition, the generation of PGD₂ and LTC₄ was inhibited in BMMC in a concentration-dependent manner with IC₅₀ values of 7.0 μg/ml and 10.9 μg/ml, respectively. When administrated orally, EBT ameliorated the mast cell-mediated PCA reaction. In the OVA-induced AR model, the increased levels of IgE were reduced by EBT. The levels of cytokines, such as IL-4, IL-5, IL-10, and IL-13 decreased in the splenocytes of EBT-treated mice. The histological analysis shows that the infiltration of inflammatory cells increased by OVA-sensitization was also reduced.

Conclusions

Taken together, these results suggested that EBT has anti-allergic and anti-inflammatory effects in vitro and in vivo models.

The antiallergic mechanisms of Citrus sunki and bamboo salt (K-ALL) in an allergic rhinitis model

The antiallergic effects of traditional medicines have long been studied. Traditional Korean medicine, Citrus sunki and bamboo salt, has been used for the treatment of allergic diseases in Korea. K-ALL, composed of Citrus sunki and bamboo salt, is a newly prepared prescription for allergic patients. To develop the new antiallergic agent, we examined the effects of K-ALL through in vivo and in vitro models. K-ALL and naringin (an active compound of K-ALL) significantly inhibited histamine release from rat peritoneal mast cells. This inhibitory effect of K-ALL on histamine release was higher than effects from other known histamine inhibitors such as bamboo salt, Citrus sunki or disodium cromoglycate. K-ALL significantly inhibited systemic anaphylactic shock induced by the compound 48/80 and passive cutaneous anaphylaxis induced by the IgE. K-ALL also inhibited production and mRNA expression of inflammatory cytokines induced by phorbol 12-myristate 13-acetate and the calcium ionophore A23187 on HMC-1 cells (a human mast cell line). In the ovalbumin-induced allergic rhinitis animal model, rub scores, histamine, IgE, inflammatory cytokines and inflammatory cell counts were all reduced by the oral or nasal administration of K-ALL (pre and posttreatment). These results indicate the great potential of K-ALL as an active immune modulator for the treatment of mast cell-mediated allergic diseases.

Suppression of voltage-gated Na(+) channels and neuronal excitability by imperatorin

Imperatorin is a naturally occurring furocoumarin compound isolated from plants such as Angelica archangelica and Cnidium monnieri. It has multiple pharmacological effects including anticonvulsant effects. Here we determined the effects of imperatorin on voltage-gated Na(+) channels (VGSC) using whole-cell patch clamp techniques in differentiated neuronal NG108-15 cells. We showed that imperatorin inhibited VGSC; such inhibition did not show state-dependence. Imperatorin caused a left shift in the steady-state inactivation curve without affecting activation gating. The inhibition of VGSC by imperatorin displayed a mild frequency-dependence. Imperatorin was also shown to inhibit VGSC and action potential amplitude without affecting voltage-gated K(+) channels in rat hippocampal CA1 neurons. In conclusion, our results suggest that imperatorin dampens neuronal excitability by inhibiting VGSC.