In vitro pharmacokinetic behavior in lung of harringtonine, an antagonist of SARS-CoV-2 associated proteins: New insights of inhalation therapy for COVID-19.

BACKGROUND: Recent studies have shown that harringtonine (HT) could specifically bind with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein and host cell transmembrane serine protease 2 (TMPRSS2) to block membrane fusion, which is an effective antagonist for SARS-CoV-2. PURPOSE: Our study focused on in-depth exploration of in vitro pharmacokinetic characteristics of HT in lung. METHODS: HPLC-fluorescence detection method was used to detect changes of HT content. Incubation systems of lung microsomes for phase I metabolism and UGT incubation systems for phase II metabolism were performed to elucidate metabolites and metabolic mechanisms of HT, and then the metabolic enzyme phenotypes for HT were clarified by chemical inhibition method and recombinant enzyme method. Through metabolomics, we comprehensively evaluated the physiological dynamic changes in SD rat and human lung microsomes, and revealed the relationship between metabolomics and pharmacological activity of HT. RESULTS: HPLC-fluorescence detection method showed strong specificity, high accuracy, and good stability for rapid quantification of HT. We confirmed that HT mainly underwent phase I metabolism, and the metabolites of HT in different species were all identified as 4'-demethyl HT, with metabolic pathway being hydrolysis reaction. CYP1A2 and CYP2E1 participated in HT metabolism, but as HT metabolism was not NADPH dependent, the esterase HCES1 in lung also played a role. The main KEGG pathways in SD rat and human lung microsomes were cortisol synthesis and secretion, steroid hormone biosynthesis and linoleic acid metabolism, respectively. The downregulated key biomarkers of 11-deoxycortisol, 21-deoxycortisol and 9(10)-EpOME suggested that HT could prevent immunosuppression and interfere with infection and replication of SARS-CoV-2. CONCLUSION: HT was mainly metabolized into 4'-demethyl HT through phase I reactions, which was mediated by CYP1A2, CYP2E1, and HCES1. The downregulation of 11-deoxycortisol, 21-deoxycortisol and 9(10)-EpOME were key ways of HT against SARS-CoV-2. Our study was of great significance for development and clinical application of HT in the treatment of COVID-19.

Cultivable Endophyte Resources in Medicinal Plants and Effects on Hosts.

With the increasing demand for medicinal plants and the increasing shortage of resources, improving the quality and yield of medicinal plants and making more effective use of medicinal plants has become an urgent problem to be solved. During the growth of medicinal plants, various adversities can lead to nutrient loss and yield decline. Using traditional chemical pesticides to control the stress resistance of plants will cause serious pollution to the environment and even endanger human health. Therefore, it is necessary to find suitable pesticide substitutes from natural ingredients. As an important part of the microecology of medicinal plants, endophytes can promote the growth of medicinal plants, improve the stress tolerance of hosts, and promote the accumulation of active components of hosts. Endophytes have a more positive and direct impact on the host and can metabolize rich medicinal ingredients, so researchers pay attention to them. This paper reviews the research in the past five years, aiming to provide ideas for improving the quality of medicinal plants, developing more microbial resources, exploring more medicinal natural products, and providing help for the development of research on medicinal plants and endophytes.

Secreted phosphoprotein 1 regulates natural compound 3',4',5,7-tetrahydroxyflavone to inhibit mast cell-mediated allergic inflammation.

BACKGROUND: Mast cells (MCs) are important effector cells in anaphylaxis and anaphylactic disease. 3',4',5,7-tetrahydroxyflavone (THF) presents in many medicinal plants and exerts a variety of pharmacological effects. In this study, we evaluated the effect of THF on C48/80-induced anaphylaxis and the mechanisms underlying its effects, including the role of secreted phosphoprotein 1 (SPP1), which has not been reported to IgE-independent MC activation. RESULTS: THF inhibited C48/80-induced Ca2+ flow and degranulation via the PLCγ/PKC/IP3 pathway in vitro. RNA-seq showed that THF inhibited the expression of SPP1 and downstream molecules. SPP1 is involved in pseudo-anaphylaxis reactions. Silencing SPP1 affects the phosphorylation of AKT and P38. THF suppressed C48/80-induced paw edema, hypothermia and serum histamine, and chemokines release in vivo. CONCLUSIONS: Our results validated SPP1 is involved in IgE-independent MC activation anaphylactoid reactions. THF inhibited C48/80-mediated anaphylactoid reactions both in vivo and in vitro, suppressed calcium mobilization and inhibited SPP1-related pathways.

α-Asarone alleviates allergic asthma by stabilizing mast cells through inhibition of ERK/JAK2-STAT3 pathway.

Asthma is a heterogeneous disease related to numerous inflammatory cells, among which mast cells play an important role in the early stages of asthma. Therefore, treatment of asthma targeting mast cells is of great research value. α-Asarone is an important anti-inflammatory component of the traditional Chinese medicine Acorus calamus L, which has a variety of medicinal values. To investigate whether α-asarone can alleviate asthma symptoms and its mechanism. In this study, we investigated the effect of α-asarone on mast cell activation in vivo and in vitro. The release of chemokines or cytokines, AHR (airway hyperresponsiveness), and mast cell activation were examined in a mast cell-dependent asthma model. Western blot was performed to determine the underlying pathway. α-Asarone inhibited the degranulation of LAD2 (laboratory allergic disease 2) cells and decreased IL-8, MCP-1, histamine, and TNF-α in vitro. α-Asarone reduced paw swelling and leakage of Evans blue, as well as serum histamine, CCL2, and TNF-α in vivo. In the asthma model, α-asarone showed an inhibitory effect on AHR, inflammation, mast cells activation, infiltration of inflammatory cells, and the release of IL-5 and IL-13 in lung tissue. α-Asarone decreased the levels of phosphorylated JAK2, phosphorylated ERK, and phosphorylated STAT3 induced by C48/80. Our findings suggest that α-asarone alleviates allergic asthma by inhibiting mast cell activation through the ERK/JAK2-STAT3 pathway.

Licochalcone A inhibits MAS-related GPR family member X2-induced pseudo-allergic reaction by suppressing nuclear migration of nuclear factor-κB.

Licochalcone A (Lico A) is a natural flavonoid belonging to the class of substituted chalcone that has various biological effects. Mast cells (MCs) are innate immune cells that mediate hypersensitivity and pseudo-allergic reactions. MAS-related GPR family member X2 (MRGPRX2) on MCs has been recognized as the main receptor for pseudo-allergic reactions. In this study, we investigated the anti-pseudo-allergy effect of Lico A and its underlying mechanism. Substance P (SP), as an MC activator, was used to establish an in vitro and in vivo model of pseudo-allergy. The in vivo effect of Lico A was investigated using passive cutaneous anaphylaxis (PCA) and active systemic allergy, along with degranulation, Ca2+ influx in vitro. SP-induced laboratory of allergic disease 2 (LAD2) cell mRNA expression was explored using RNA-seq, and Lico A inhibited LAD2 cell activation by reverse transcription polymerase chain reaction (RT-PCR), western blotting, and immunofluorescence staining. Lico A showed an inhibitory effect on SP-induced MC activation and pseudo-allergy both in vitro and in vivo. The nuclear factor (NF)-κB pathway is involved in MRGPRX2 induced MC activation, which is inhibited by Lico A. In conclusion, Lico A inhibited the pseudo-allergic reaction mediated by MRGPRX2 by blocking NF-κB nuclear migration.

Three salvianolic acids inhibit 2019-nCoV spike pseudovirus viropexis by binding to both its RBD and receptor ACE2.

Since December 2019, the new coronavirus (also known as severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2, 2019-nCoV])-induced disease, COVID-19, has spread rapidly worldwide. Studies have reported that the traditional Chinese medicine Salvia miltiorrhiza possesses remarkable antiviral properties; however, the anti-coronaviral activity of its main components, salvianolic acid A (SAA), salvianolic acid B (SAB), and salvianolic acid C (SAC) is still debated. In this study, we used Cell Counting Kit-8 staining and flow cytometry to evaluate the toxicity of SAA, SAB, and SAC on ACE2 (angiotensin-converting enzyme 2) high-expressing HEK293T cells (ACE2h cells). We found that SAA, SAB, and SAC had a minor effect on the viability of ACE2h cells at concentrations below 100 µM. We further evaluated the binding capacity of SAA, SAB, and SAC to ACE2 and the spike protein of 2019-nCoV using molecular docking and surface plasmon resonance. They could bind to the receptor-binding domain (RBD) of the 2019-nCoV with a binding constant (KD ) of (3.82 ± 0.43) e-6 M, (5.15 ± 0.64)e-7 M, and (2.19 ± 0.14)e-6 M; and bind to ACE2 with KD (4.08 ± 0.61)e-7 M, (2.95 ± 0.78)e-7 M, and (7.32 ± 0.42)e-7 M, respectively. As a result, SAA, SAB, and SAC were determined to inhibit the entry of 2019-nCoV Spike pseudovirus with an EC50 of 11.31, 6.22, and 10.14 µM on ACE2h cells, respectively. In conclusion, our study revealed that three Salvianolic acids can inhibit the entry of 2019-nCoV spike pseudovirus into ACE2h cells by binding to the RBD of the 2019-nCoV spike protein and ACE2 protein.

α-Linolenic acid attenuates pseudo-allergic reactions by inhibiting Lyn kinase activity.

BACKGROUND: Pseudo-allergic reactions are potentially fatal hypersensitivity responses caused by mast cell activation. α-linolenic acid (ALA) is known for its anti-allergic properties. However, its potential anti-pseudo-allergic effects were not much investigated. PURPOSE: To investigate the inhibitory effects of ALA on IgE-independent allergy in vitro, and in vivo, as well as the mechanism underlying its effects. METHODS/STUDY DESIGNS: The anti-anaphylactoid activity of ALA was evaluated in passive cutaneous anaphylaxis reaction (PCA) and systemic anaphylaxis models. Calcium imaging was used to assess intracellular Ca2+ mobilization. The release of cytokines and chemokines was measured using enzyme immunoassay kits. Western blot analysis was conducted to investigate the molecules of Lyn-PLCγ-IP3R-Ca2+ and Lyn-p38/NF-κB signaling pathway. RESULTS: ALA (0, 1.0, 2.0, and 4.0 mg/kg) dose-dependently reduced serum histamine, chemokine release, vasodilation, eosinophil infiltration, and the percentage of degranulated mast cells in C57BL/6 mice. In addition, ALA (0, 50, 100, and 200 µM) reduced Compound 48/80 (C48/80) (30 µg/ml)-or Substance P (SP) (4 µg/ml)-induced calcium influx, mast cell degranulation and cytokines and chemokine release in Laboratory of Allergic Disease 2 (LAD2) cells via Lyn-PLCγ-IP3R-Ca2+ and Lyn-p38/NF-κB signaling pathway. Moreover, ALA (0, 50, 100, and 200 µM) inhibited C48/80 (30 µg/ml)- and SP (4 µg/ml)-induced calcium influx in Mas-related G-protein coupled receptor member X2 (MrgX2)-HEK293 cells and in vitro kinase assays confirmed that ALA inhibited the activity of Lyn kinase. In response to 200 µM of ALA, the activity of Lyn kinase by (7.296 ± 0.03751) × 10-5 units/µl and decreased compared with C48/80 (30 µg/ml) by (8.572 ± 0.1365) ×10-5 units/µl. CONCLUSION: Our results demonstrate that ALA might be a potential Lyn kinase inhibitor, which could be used to treat pseudo-allergic reaction-related diseases such as urticaria.

Chloroquine and hydroxychloroquine as ACE2 blockers to inhibit viropexis of 2019-nCoV Spike pseudotyped virus.

BACKGROUND: The novel coronavirus disease (2019-nCoV) has been affecting global health since the end of 2019 and there is no sign that the epidemic is abating . The major issue for controlling the infectious is lacking efficient prevention and therapeutic approaches. Chloroquine (CQ) and Hydroxychloroquine (HCQ) have been reported to treat the disease, but the underlying mechanism remains controversial. PURPOSE: The objective of this study is to investigate whether CQ and HCQ could be ACE2 blockers and used to inhibit 2019-nCoV virus infection. METHODS: In our study, we used CCK-8 staining, flow cytometry and immunofluorescent staining to evaluate the toxicity and autophagy of CQ and HCQ, respectively, on ACE2 high-expressing HEK293T cells (ACE2h cells). We further analyzed the binding character of CQ and HCQ to ACE2 by molecular docking and surface plasmon resonance (SPR) assays, 2019-nCoV spike pseudotyped virus was also used to observe the viropexis effect of CQ and HCQ in ACE2h cells. RESULTS: Results showed that HCQ is slightly more toxic to ACE2h cells than CQ. Both CQ and HCQ could bind to ACE2 with KD = (7.31 ± 0.62)e-7 M and (4.82 ± 0.87)e-7 M, respectively. They exhibit equivalent suppression effect for the entrance of 2019-nCoV spike pseudotyped virus into ACE2h cells. CONCLUSIONS: CQ and HCQ both inhibit the entrance 2019-nCoV into cells by blocking the binding of the virus with ACE2. Our findings provide novel insights into the molecular mechanism of CQ and HCQ treatment effect on virus infection.

Baicalin induces Mrgprb2-dependent pseudo-allergy in mice.

Baicalin, a component of traditional Chinese medicine, is one of the main compounds present in Scutellaria baicalensis Georgi. Pseudo-allergy induced by the injection of these medicines is a frequent adverse drug reaction. Therefore, elucidation of the anaphylactoid reaction of baicalin and its underlying mechanisms are important. Mast cells are primary effectors of allergic reactions, including pseudo-allergy. Studies have shown that Mrgprx2 in human mast cells is a specific receptor that is crucial for pseudo-allergic drug reactions, Mrgprb3 is the rat ortholog of human Mrgprx2, which in mice is designated as Mrgprb2. Here, we aimed to investigate baicalin-induced pseudo-allergy and the association of Mrgprb3 and Mrgprb2 with this effect. We examined the allergenic effect of baicalin on RBL-2H3 cells and Mrgprb3-knockdown RBL-2H3 cells. Mrgprb2-expressing HEK293 cells and Mrgprb2-knockout mice were used to evaluate the role of Mrgprb2 in baicalin-induced allergy. Baicalin was found to dose-dependently induce pseudo-allergy both in vitro and in vivo. RBL-2H3 cells were activated by baicalin, whereas in Mrgprb3-knockout RBL-2H3 cells, baicalin showed a negligible effect on cell activation. Furthermore, baicalin activated the Mrgprb2-expressing HEK293 cells. Our data showed that baicalin did not induce allergy in Mpgprb2-knockout mice. We conclude that baicalin induces pseudo-allergy via Mrgprb2 in mice.

Isoimperatorin reduces the effective dose of dexamethasone in a murine model of asthma by inhibiting mast cell activation.

Adverse effects that result from dexamethasone (DEX) use are common and serious in patients with asthma. Therefore, alternative anti-inflammatory treatments are being investigated. Isoimperatorin (ISO), an active natural furocoumarin, possesses multiple pharmacological properties, including an anti-inflammation effect. In this study, investigations were conducted on the effect of ISO on mast cell (MC) activation in vitro and whether ISO could reduce the effective dose of DEX in a mast cell-dependent murine model of asthma in vivo. Calcium imaging was used to assess intracellular Ca2+ mobilization. Enzyme-linked immunosorbent assay was used to measure the chemokines release. Western blot analysis was conducted to investigate the underlying pathway. Airway inflammation and hyperresponsiveness (AHR) were examined in an asthma model. ISO inhibited Ca2+ flux and MC degranulation via Lyn/PLCγ1/PKC, ERK, and P38 MAPK pathways. In the asthma model, ISO, in combination with DEX, showed an additive inhibitory effect on AHR, inflammation, and the number of activated MCs in the lungs and decreased the levels of interleukin (IL)-4, IL-5, IL-6, IL-13, tumor necrosis factor (TNF)-a, and C-C motif chemokine ligand (CCL)-2 in bronchoalveolar lavage fluid. A combination of DEX and ISO may be appropriate if a decrease in the steroid dose is desired owing to dose-dependent adverse effects.

Discovery and analysis the anti-pseudo-allergic components from Perilla frutescens leaves by overexpressed MRGPRX2 cell membrane chromatography coupled with HPLC-ESI-IT-TOF system.

OBJECTIVES: Screen and identify the anti-pseudo-allergic activity components of Perilla frutescens leaves that interacted with MRGPRX2 (a new reported pseudo-allergic reaction-related receptor). METHODS: An overexpressed MRGPRX2 cell membrane chromatography (CMC) coupled with HPLC-ESI-IT-TOF system has been established to screen and identify the effective components from P. frutescens leaves. A frontal analysis method was performed to investigate the binding affinity between ligands and MRGPRX2. Their activity of relieving pseudo-allergic reaction was evaluated in vitro by histamine release assay, ß-hexosaminidase release assay and intracellular Ca2+ mobilization assay. KEY FINDINGS: Extract of P. frutescens leaves was proved to be effective in anti-pseudo-allergic reaction by inhibiting MRGPRX2. Apigenin (API) and rosmarinic acid (ROS) were confirmed to be the potential anti-allergy compounds that could bind with MRGPRX2. The binding affinity (KD ) of ROS and API with MRGPRX2 was (8.79 ± 0.13) × 10-8  m and (6.54 ± 1.69) × 10-8  m, respectively. The IC50 of API inhibiting laboratory of allergic disease 2 cells degranulation was also determined to be (51.96 ± 0.18) µm. CONCLUSIONS: A MRGPRX2/CMC coupled with HPLC-ESI-IT-TOF system was successfully established and applied to discover the effective components from P. frutescens leaves.

Inhibitory function of Shikonin on MRGPRX2-mediated pseudo-allergic reactions induced by the secretagogue.

BACKGROUND: Mast cells (MCs) are crucial effectors in allergic disorders by secreting inflammatory mediators. The Mas-related G-protein-coupled receptor X2 (Mrgprx2) was shown to have a key role in IgE-independent allergic reactions. Therefore, potential drug candidates that directly target Mrgprx2 could be used to treat pseudo-allergic diseases. Shikonin, an active ingredient derived from Lithospermum erythrorhizon Sieb. et Zucc has been used for its anti-inflammatory properties since ancient China. PURPOSE: To investigate the inhibitory effects of Shikonin on IgE-independent allergy both in vitro and in vivo, as well as the mechanism underlying its effects. METHODS/STUDY DESIGNS: The anti-anaphylactoid activity of Shikonin was evaluated in PCA and systemic anaphylaxis models, Calcium imaging was used to assess intracellular Ca2+ mobilization. The release of cytokines and chemokines was measured using enzyme immunoassay kits. Western blot analysis was conducted to investigate the molecules of PLCγ-PKC-IP3 signaling pathway. The analytical method of surface plasmon resonance was employed to study the interaction between Shikonin and potential target protein Mrgprx2. RESULTS: Shikonin can suppress compound 48/80 (C48/80)-induced PCA, active systemic anaphylaxis, and MCs degranulation in mice in a dose-dependent manner. In addition, Shikonin reduced C48/80-induced calcium flux and suppressed LAD2 cell degranulation via PLCγ-PKC-IP3 signaling pathway. Moreover, Shikonin was found to inhibit C48/80-induced Mrgprx2 expression in HEK cells, displaying specific interactions with the Mrgprx2 protein. CONCLUSION: Shikonin could be a potential antagonist of Mrgprx2, thereby inhibiting pseudo-allergic reactions through Ca2+ mobilization.

Paeoniflorin inhibits MRGPRX2-mediated pseudo-allergic reaction via calcium signaling pathway.

Mas-related G protein-coupled receptor-X2 (MRGPRX2) expressed on mast cells (MCs) has been shown to be a pivotal target for pseudo-allergic diseases. Therefore, MRGPRX2 might be a therapeutic target for allergic contact dermatitis, atopic dermatitis, and red man syndrome. Paeoniflorin (PF) was reported to have an antiinflammatory effect in neuroinflammation, enteritis, and so forth. In this study, we investigated the anti-pseudo-allergic effect of PF and the underlying molecular mechanisms. Our results showed that PF can suppress compound 48/80 (C48/80)-induced PCA and MCs degranulation in vivo, in a dose-dependent manner. Moreover, PF can reduce C48/80-induced calcium influx and suppress MC degranulation and chemokines release in vitro. PF can downregulate the phosphorylation levels of key kinases in PLCγ-regulated calcium influx and subsequent cytokine synthesis pathways. Our study revealed that PF could inhibit C48/80-induced allergic responses both in vivo and in vitro. As such, it may be regarded as a novel inhibitor for preventing MRGPRX2-mediated allergic diseases.

Neohesperidin suppresses IgE-mediated anaphylactic reactions and mast cell activation via Lyn-PLC-Ca2+ pathway.

Mast cells play an essential role in IgE-FcεR1-mediated allergic diseases. Citrus aurantium is a prolific source of flavonoids with various biological activities, including anti-inflammatory, antioxidant, and anti-tumor efficacies. Neohesperidin is a novel flavonoid isolated from the leaves of C. aurantium. In this study, the anti-allergic and anti-inflammatory potentials of neohesperidin were investigated along with its molecular mechanism. The anti-anaphylactic activity of neohesperidin was evaluated through hind paw extravasation study in mice. Calcium imaging was used to assess intracellular Ca2+ mobilization. The levels of cytokines and chemokines were measured using enzyme immunoassay kits. Western blotting was used to explore the related molecular signaling pathways. Neohesperidin suppressed IgE-induced mast cell activations, including degranulation and secretion of cytokines and eicosanoids through inhibiting phosphorylation of Lyn kinase. Neohesperidin inhibited the release of histamine and other proinflammatory cytokines through a mast cell-dependent passive cutaneous anaphylaxis animal model. Histological studies demonstrated that neohesperidin substantially inhibited IgE-induced cellular infiltration and attenuated mast cell activation in skin tissue. In conclusion, our study revealed that neohesperidin could inhibit allergic responses in vivo and in vitro, and the molecule may be regarded as a novel agent for preventing mast cell-immediate and delayed allergic diseases.