Myricetin possesses the potency against SARS-CoV-2 infection through blocking viral-entry facilitators and suppressing inflammation in rats and mice.

BACKGROUND: Myricetin (3,5,7-trihydroxy-2-(3,4,5-tri hydroxyphenyl)-4-benzopyrone) is a common flavonol extracted from many natural plants and Chinese herb medicines and has been demonstrated to have multiple pharmacological activities, such as anti-microbial, anti-thrombotic, neuroprotective, and anti-inflammatory effects. Previously, myricetin was reported to target Mpro and 3CL-Pro-enzymatic activity to SARS-CoV-2. However, the protective value of myricetin on SARS-Cov-2 infection through viral-entry facilitators has not yet been comprehensively understood. PURPOSE: The aim of the current study was to evaluate the pharmacological efficacy and the mechanisms of action of myricetin against SARS-CoV-2 infection both in vitro and in vivo. METHODS: The inhibitory effects of myricetin on SARS-CoV-2 infection and replication were assessed on Vero E6 cells. Molecular docking analysis and bilayer interferometry (BLI) assays, immunocytochemistry (ICC), and pseudoviruses assays were performed to evaluate the roles of myricetin in the intermolecular interaction between the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein and angiotensin-converting enzyme 2 (ACE2). The anti-inflammatory potency and mechanisms of myricetin were examined in THP1 macrophages in vitro, as well as in carrageenan-induced paw edema, delayed-type hypersensitivity (DTH) induced auricle edema, and LPS-induced acute lung injury (ALI) animal models. RESULTS: The results showed that myricetin was able to inhibit binding between the RBD of the SARS-CoV-2 S protein and ACE2 through molecular docking analysis and BLI assay, demonstrating its potential as a viral-entry facilitator blocker. Myricetin could also significantly inhibit SASR-CoV-2 infection and replication in Vero E6 cells (EC50 55.18 µM), which was further validated with pseudoviruses containing the RBD (wild-type, N501Y, N439K, Y453F) and an S1 glycoprotein mutant (S-D614G). Moreover, myricetin exhibited a marked suppressive action on the receptor-interacting serine/threonine protein kinase 1 (RIPK1)-driven inflammation and NF-kappa B signaling in THP1 macrophages. In animal model studies, myricetin notably ameliorated carrageenan-induced paw edema in rats, DTH induced auricle edema in mice, and LPS-induced ALI in mice. CONCLUSION: Our findings showed that myricetin inhibited HCoV-229E and SARS-CoV-2 replication in vitro, blocked SARS-CoV-2 virus entry facilitators and relieved inflammation through the RIPK1/NF-κB pathway, suggesting that this flavonol has the potential to be developed as a therapeutic agent against COVID-19.

Integrated network pharmacology analysis, molecular docking, LC-MS analysis and bioassays revealed the potential active ingredients and underlying mechanism of Scutellariae radix for COVID-19.

Scutellariae radix ("Huang-Qin" in Chinese) is a well-known traditional herbal medicine and popular dietary supplement in the world, extensively used in prescriptions of TCMs as adjuvant treatments for coronavirus pneumonia 2019 (COVID-19) patients in China. According to the differences in its appearance, Scutellariae radix can be classified into two kinds: ZiQin (1∼3 year-old Scutellariae baicalensis with hard roots) and KuQin (more than 3 year-old S. baicalensis with withered pithy roots). In accordance with the clinical theory of TCM, KuQin is superior to ZiQin in cooling down the heat in the lung. However, the potential active ingredients and underlying mechanisms of Scutellariae radix for the treatment of COVID-19 remain largely unexplored. It is still not clear whether there is a difference in the curative effect of ZiQin and KuQin for the treatment of COVID-19. In this research, network pharmacology, LC-MS based plant metabolomics, and in vitro bioassays were integrated to explore both the potential active components and mechanism of Scutellariae radix for the treatment of COVID-19. As the results, network pharmacology combined with molecular docking analysis indicated that Scutellariae radix primarily regulates the MAPK and NF-κB signaling pathways via active components such as baicalein and scutellarin, and blocks SARS-CoV-2 spike binding to human ACE2 receptors. In vitro bioassays showed that baicalein and scutellarein exhibited more potent anti-inflammatory and anti-infectious effects than baicalin, the component with the highest content in Scutellariae radix. Moreover, baicalein inhibited SARS-CoV-2's entry into Vero E6 cells with an IC50 value of 142.50 µM in a plaque formation assay. Taken together, baicalein was considered to be the most crucial active component of Scutellariae radix for the treatment of COVID-19 by integrative analysis. In addition, our bioassay study revealed that KuQin outperforms ZiQin in the treatment of COVID-19. Meanwhile, plant metabolomics revealed that baicalein was the compound with the most significant increase in KuQin compared to ZiQin, implying the primary reason for the superiority of KuQin over ZiQin in the treatment of COVID-19.

Lianhuaqingwen capsule inhibits non-lethal doses of influenza virus-induced secondary Staphylococcus aureus infection in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Lianhuaqingwen capsule (LH-C) is a traditional Chinese medicine (TCM), consisting of two prescriptions, Ma-xing-shi-gan-tang (MXSGT) and Yinqiao San. It has been proven to have antiviral, antibacterial, and immunomodulatory effects in recent years. Clinically, it is commonly used in the treatment of respiratory tract infections. AIM OF THE STUDY: It was demonstrated in our previous studies that LH-C has an effect of antivirus and inhibits influenza virus-induced bacterial adhesion to respiratory epithelial cells through down-regulation of cell adhesion molecules in vitro. However, LH-C's effect against influenza-induced secondary bacterial infection in animal studies remains unclear. Therefore, in the present study, we established a mouse model of infection with non-lethal doses of influenza virus(H1N1) and secondary infection of Staphylococcus aureus (S. aureus), to investigate the potential effects of LH-C. METHODS: Experiments were carried out on BALB/c mice infecting non-lethal doses of H1N1 and non-lethal doses of S. aureus, and the viral, and bacterial doses were determined by observing and recording changes in the body weight, mortality, and pathological changes. Moreover, after LH-C treatment, the survival rate, body weight, lung index, viral titers, bacterial colonies, pathological changes, and the inflammatory cytokines in the mouse model have all been systematically determined. RESULTS: In the superinfection models of H1N1 and S. aureus, the mortality rate was 100% in groups of mice infected with 20 PFU/50 µL of H1N1 and 105 CFU/mL of S. aureus, 20 PFU/50 µL of H1N1 and 106 CFU/mL of S. aureus, 4 PFU/50 µL of H1N1 and 106 CFU/mL of S. aureus. The mortality rate was 50% in the group of mice infected with 4 PFU/50 µL of H1N1 and 105 CFU/mL of S. aureus. The mortality rate was 37.5% in the group of mice infected with 20 PFU/50 µL of H1N1 alone and in the group of mice infected with 2 PFU/50 µL of H1N1 and 106 CFU/mL of S. aureus. The mortality rate in the group of mice infected with 2 PFU/50 µL of H1N1 and 106 CFU/mL of S. aureus was 30%. The infected mice of 2 PFU/50 µL of H1N1 and 106 CFU/mL of S. aureus had a weight loss of nearly 10%. About the histopathological changes in the lung tissue of infection mice, severe lung lesions were found in the superinfection models. LH-C improved survival in the superinfected mice, significantly reduced lung index, lowered viral titers and bacterial loads, and alleviated lung damage. It reduced lung inflammation by down-regulating mRNA expression levels of inflammatory mediators like IL-6, IL-1ß, IL-10, TNF-α, IFN-ß, MCP-1, and RANTES. CONCLUSIONS: We found that superinfection from non-lethal doses of S. aureus following non-lethal doses of H1N1 was equally fatal in mice, confirming the severity of secondary infections. The ability of LH-C to alleviate lung injury resulting from secondary S. aureus infection induced by H1N1 was confirmed. These findings provided a further assessment of LH-C, suggesting that LH-C may have good therapeutic efficacy in influenza secondary bacterial infection disease.

Chaiqin Qingning Capsule Inhibits Influenza Virus Infection and Inflammation In Vitro and In Vivo.

BACKGROUND: Chaiqin Qingning Capsule (CQ-C) is a traditional Chinese medicine (TCM) formula commonly used to treat respiratory infectious diseases in China. The aim of this study was to detect the effect and mechanism of CQ-C treated with influenza virus in vitro and vivo. METHODS: The cytotoxicity and antiviral activity of CQ-C in vitro was determined by methyl thiazolyl tetrazolium (MTT) assay. The regulation of CQ-C on cytokine/chemokine expression was evaluated using RT-qPCR. In addition, the effect of CQ-C on the pathway protein, NF-κB, and its phosphorylation level was verified by western blotting. After virus inoculation, BALB/c mice were administered with CQ-C of different concentrations for 7 days. Body weight, viral titer, lung pathology, and mortality of the mice were measured, and the level of inflammatory cytokines was also examined using real-time RT-qPCR. RESULTS: CQ-C inhibited the proliferation of influenza virus of various strains in vitro, with the 50% inhibitory concentration (IC50) ranging from 49 to 59 µg/mL. CQ-C downregulated virus-induced gene expression of IL-6, TNF-α, CXCL8, CXCL10, CCL5, and COX-2 in a dose-dependent manner in A549 cells. Also, CQ-C inhibited the expression of NF-κB protein of the signaling pathway. Moreover, a decrease of the lung index and mortality of mice was observed in the CQ-C (1 g/kg/d) group. The related cytokine/chemokine expression was also decreased in the early stages of infection in the mRNA level. CONCLUSION: As a clinically applied Chinese prescription, our study shows that CQ-C has a wide range of effects on several influenza viruses. Moreover, CQ-C could play an important role in anti-influenza activity and anti-inflammation in vitro and in vivo. Thus, CQ-C may be a promising treatment option for influenza.

Isoforskolin, an adenylyl cyclase activator, attenuates cigarette smoke-induced COPD in rats.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterized by limited airflow due to pulmonary and alveolar abnormalities from exposure to cigarette smoke (CS). Current therapeutic drugs are limited and the development of novel treatments to prevent disease progression is challenging. Isoforskolin (ISOF) from the plant Coleus forskohlii is an effective activator of adenylyl cyclase (AC) isoforms. Previously we found ISOF could attenuate acute lung injury in animal models, while the effect of ISOF on COPD has not been elucidated. PURPOSE: In this study, we aimed to evaluate the efficacy of ISOF on COPD and reveal its potential mechanisms. METHODS: A rat model of COPD was established by long-term exposure to CS, then the rats were orally administered with ISOF (0.5, 1 and 2 mg/kg). The pulmonary function, lung morphology, inflammatory cells and cytokines in serum or bronchoalveolar lavage fluid (BALF) were evaluated. Transcriptomics, proteomics and network pharmacology analysis were utilized to identify potential mechanisms of ISOF. Droplet digital PCR was used to detect the mRNA expression of AC1-10 in donor lung tissues. AC activation was determined in recombinant human embryonic kidney 293 (HEK293) cells stably expressing human AC isoforms. In addition, ISOF caused trachea relaxation ex vivo were assessed in isolated trachea rings from guinea pigs. RESULTS: ISOF significantly ameliorated pathological damage of lung tissue and improved pulmonary function in COPD rats. ISOF treatment decreased the number of inflammatory cells in peripheral blood, and also the levels of pro-inflammatory cytokines in serum and BALF. Consistent with omics-based analyses, ISOF markedly downregulated the mTOR level in lung tissue. Flow cytometry analysis revealed that ISOF treatment reduced the ratio of Th17/Treg cells in peripheral blood. Furthermore, the expression levels of AC1 and AC2 are relatively higher than other AC isoforms in normal lung tissues, and ISOF could potently activate AC1 and AC2 in vitro and significantly relax isolated guinea pig trachea. CONCLUSION: Collectively, our studies suggest that ISOF exerts its anti-COPD effect by improving lung function, anti-inflammation and trachea relaxation, which may be related to AC activation, mTOR signaling and Th17/Treg balance.

Identification of natural compounds as SARS-CoV-2 entry inhibitors by molecular docking-based virtual screening with bio-layer interferometry.

Coronavirus Disease 2019 (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which enter the host cells through the interaction between its receptor binding domain (RBD) of spike glycoprotein with angiotensin-converting enzyme 2 (ACE2) receptor on the plasma membrane of host cell. Neutralizing antibodies and peptide binders of RBD can block viral infection, however, the concern of accessibility and affordability of viral infection inhibitors has been raised. Here, we report the identification of natural compounds as potential SARS-CoV-2 entry inhibitors using the molecular docking-based virtual screening coupled with bilayer interferometry (BLI). From a library of 1871 natural compounds, epigallocatechin gallate (EGCG), 20(R)-ginsenoside Rg3 (RRg3), 20(S)-ginsenoside Rg3 (SRg3), isobavachalcone (Ibvc), isochlorogenic A (IscA) and bakuchiol (Bkc) effectively inhibited pseudovirus entry at concentrations up to 100 µM. Among these compounds, four compounds, EGCG, Ibvc, salvianolic acid A (SalA), and isoliensinine (Isl), were effective in inhibiting SARS-CoV-2-induced cytopathic effect and plaque formation in Vero E6 cells. The EGCG was further validated with no observable animal toxicity and certain antiviral effect against SARS-CoV-2 pseudovirus mutants (D614G, N501Y, N439K & Y453F). Interestingly, EGCG, Bkc and Ibvc bind to ACE2 receptor in BLI assay, suggesting a dual binding to RBD and ACE2. Current findings shed some insight into identifications and validations of SARS-CoV-2 entry inhibitors from natural compounds.

Phillyrin (KD-1) exerts anti-viral and anti-inflammatory activities against novel coronavirus (SARS-CoV-2) and human coronavirus 229E (HCoV-229E) by suppressing the nuclear factor kappa B (NF-κB) signaling pathway.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has extensively and rapidly spread in the world, causing an outbreak of acute infectious pneumonia. However, no specific antiviral drugs or vaccines can be used. Phillyrin (KD-1), a representative ingredient of Forsythia suspensa, possesses anti-inflammatory, anti-oxidant, and antiviral activities. However, little is known about the antiviral abilities and mechanism of KD-1 against SARS-CoV-2 and human coronavirus 229E (HCoV-229E). PURPOSE: The study was designed to investigate the antiviral and anti-inflammatory activities of KD-1 against the novel SARS-CoV-2 and HCoV-229E and its potential effect in regulating host immune response in vitro. METHODS: The antiviral activities of KD-1 against SARS-CoV-2 and HCoV-229E were assessed in Vero E6 cells using cytopathic effect and plaque-reduction assay. Proinflammatory cytokine expression levels upon infection with SARS-CoV-2 and HCoV-229E infection in Huh-7 cells were measured by real-time quantitative PCR assays. Western blot assay was used to determine the protein expression of nuclear factor kappa B (NF-κB) p65, p-NF-κB p65, IκBα, and p-IκBα in Huh-7 cells, which are the key targets of the NF-κB pathway. RESULTS: KD-1 could significantly inhibit SARS-CoV-2 and HCoV-229E replication in vitro. KD-1 could also markedly reduce the production of proinflammatory cytokines (TNF-α, IL-6, IL-1ß, MCP-1, and IP-10) at the mRNA levels. Moreover, KD-1 could significantly reduce the protein expression of p-NF-κB p65, NF-κB p65, and p-IκBα, while increasing the expression of IκBα in Huh-7 cells. CONCLUSIONS: KD-1 could significantly inhibit virus proliferation in vitro, the up-regulated expression of proinflammatory cytokines induced by SARS-CoV-2 and HCoV-229E by regulating the activity of the NF-кB signaling pathway. Our findings indicated that KD-1 protected against virus attack and can thus be used as a novel strategy for controlling the coronavirus disease 2019.

Total alkaloids from Alstonia scholaris inhibit influenza a virus replication and lung immunopathology by regulating the innate immune response.

BACKGROUND: Alstonia scholaris is a folk medicine used to treat cough, asthma and chronic obstructive pulmonary disease in China. Total alkaloids (TA) from A. scholaris exhibit anti-inflammatory properties in acute respiratory disease, which suggests their possible anti-inflammatory effect on influenza virus infection. PURPOSE: To assess the clinical use of TA by demonstrating their anti-influenza and anti-inflammatory effects and the possible mechanism underlying the effect of TA on influenza A virus (IAV) infection in vitro and to reveal the inhibitory effect of TA on lung immunopathology caused by IAV infection. METHODS: Antiviral and anti-inflammatory activities were assessed in Madin-Darby canine kidney (MDCK) and A549 cells and U937-derived macrophages infected with influenza A/PR/8/34 (H1N1) virus. Proinflammatory cytokine levels were measured by real-time quantitative PCR and Bio-Plex assays. The activation of innate immune signaling induced by H1N1 virus in the absence or presence of TA was detected in A549 cells by Western blot. Furthermore, mice were infected intranasally with H1N1 virus and treated with TA (50, 25 and 12.5 mg/kg/d) or oseltamivir (60 mg/kg/d) for 5 days in vivo. The survival rates and body weight were recorded, and the viral titer, proinflammatory cytokine levels, innate immune cell populations and histopathological changes in the lungs were analyzed. RESULTS: TA significantly inhibited viral replication in A549 cells and U937-derived macrophages and markedly reduced cytokine and chemokine production at the mRNA and protein levels. Furthermore, TA blocked the activation of pattern recognition receptor (PRR)- and IFN-activated signal transduction in A549 cells. Critically, TA also increased the survival rate, reduced the viral titer, suppressed proinflammatory cytokine production and innate immune cell infiltration and improved lung histopathology in a lethal PR8 mouse model. CONCLUSION: TA exhibits anti-viral and anti-inflammatory effects against IAV infection by interfering with PRR- and IFN-activated signal transduction.

Liu Shen capsule shows antiviral and anti-inflammatory abilities against novel coronavirus SARS-CoV-2 via suppression of NF-κB signaling pathway.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread worldwide through person-to-person contact, causing a public health emergency of international concern. At present, there is no specific antiviral treatment recommended for SARS-CoV-2 infection. Liu Shen capsule (LS), a traditional Chinese medicine, has been proven to have a wide spectrum of pharmacological properties, such as anti-inflammatory, antiviral and immunomodulatory activities. However, little is known about the antiviral effect of LS against SARS-CoV-2. Herein, the study was designed to investigate the antiviral activity of SARS-CoV-2 and its potential effect in regulating the host's immune response. The inhibitory effect of LS against SARS-CoV-2 replication in Vero E6 cells was evaluated by using the cytopathic effect (CPE) and plaque reduction assay. The number of virions of SARS-CoV-2 was observed under transmission electron microscope after treatment with LS. Proinflammatory cytokine expression levels upon SARS-CoV-2 infection in Huh-7 cells were measured by real-time quantitative PCR assays. The results showed that LS could significantly inhibit SARS-CoV-2 replication in Vero E6 cells, and reduce the number of virus particles and it could markedly reduce pro-inflammatory cytokines (TNF-α, IL-6, IL-1ß, IL-8, CCL-2/MCP-1 and CXCL-10/IP-10) production at the mRNA levels. Moreover, the expression of the key proteins in the NF-κB/MAPK signaling pathway was detected by western blot and it was found that LS could inhibit the expression of p-NF-κB p65, p-IκBα and p-p38 MAPK, while increasing the expression of IκBα. These findings indicate that LS could inhibit SARS-CoV-2 virus infection via downregulating the expression of inflammatory cytokines induced virus and regulating the activity of NF-κB/MAPK signaling pathway in vitro, making its promising candidate treatment for controlling COVID-19 disease.

The Chinese prescription lianhuaqingwen capsule exerts anti-influenza activity through the inhibition of viral propagation and impacts immune function.

BACKGROUND: Lianhuaqingwen Capsule (LH-C) is a traditional Chinese medicine (TCM) formula used to treat respiratory tract infectious diseases in Chinese. The aim of this study was to determine the antiviral activity of LH-C and its immunomodulatory effects on viral infection. METHOD: The in vitro cytotoxicity and antiviral activity of LH-C was determined by MTT and Plaque reduction assays. Time course study under single-cycle virus growth conditions were used to determine which stage of viral replication was blocked. The effect of LH-C on the nuclear export of the viral nucleoprotein was examined using an indirect immunofluorescence assay. The regulation to different signaling transduction events and cytokine/chemokine expression of LH-C was evaluated using Western blotting and real-time RT-PCR. After virus inoculation, BALB/c mice were administered with LH-C of different concentrations for 5 days. Body-weight, viral titers and lung pathology of the mice were measured, the level of inflammatory cytokines were also examined using real-time RT-PCR. RESULTS: LH-C inhibited the proliferation of influenza viruses of various strain in vitro, with the 50% inhibitory concentration (IC50) ranging from 0.35 to 2 mg/mL. LH-C blocked the early stages (0-2 h) of virus infection, it also suppressed virus-induced NF-kB activation and alleviated virus-induced gene expression of IL-6, IL-8, TNF-a, IP-10, and MCP-1 in a dose-dependent manner. LH-C treatment efficiently impaired the nuclear export of the viral RNP. A decrease of the viral titers in the lungs of mice were observed in groups administered with LH-C. The level of inflammatory cytokines were also decreased in the early stages of infection. CONCLUSIONS: LH-C, as a TCM prescription, exerts broad-spectrum effects on a series of influenza viruses, including the newly emerged H7N9, and particularly regulates the immune response of virus infection. Thus, LH-C might be a promising option for treating influenza virus infection.