Montelukast Inhibits HCoV-OC43 Infection as a Viral Inactivator

Zafirlukast, as a viral inactivator, potently inhibits infection of several flaviviruses, including Zika virus, dengue virus, and yellow fever virus

Zika virus (ZIKV) is one of the mosquito-borne flaviviruses that exhibits a unique tropism to nervous systems and is associated with Guillain-Barre syndrome and congenital Zika syndrome (CZS). Dengue virus (DENV) and yellow fever virus (YFV), the other two mosquito-borne flaviviruses, have also been circulating for a long time and cause severe diseases, such as dengue hemorrhagic fever and yellow fever, respectively. However, there are no safe and effective antiviral drugs approved for the treatment of infections or coinfections of these flaviviruses. Here, we found that zafirlukast, a pregnancy-safe leukotriene receptor antagonist, exhibited potent antiviral activity against infections of ZIKV strains from different lineages in different cell lines, as well as against infections of DENV-2 and YFV 17D. Mechanistic studies demonstrated that zafirlukast directly and irreversibly inactivated these flaviviruses by disrupting the integrity of the virions, leading to the loss of viral infectivity, hence inhibiting the entry step of virus infection. Considering its efficacy against flaviviruses, its safety for pregnant women, and its neuroprotective effect, zafirlukast is a promising candidate for prophylaxis and treatment of infections or coinfections of ZIKV, DENV, and YFV, even in pregnant women.

The nucleoside analog 4'-fluorouridine suppresses the replication of multiple enteroviruses by targeting 3D polymerase

Human enteroviruses are the major pathogens causing hand-foot-and-mouth disease in infants and young children throughout the world, and infection with enterovirus is also associated with severe complications, such as aseptic meningitis and myocarditis. However, there are no antiviral drugs available to treat enteroviruses infection at present. In this study, we found that 4'-fluorouridine (4'-FlU), a nucleoside analog with low cytotoxicity, exhibited broad-spectrum activity against infections of multiple enteroviruses with EC50 values at low micromolar levels, including coxsackievirus A10 (CV-A10), CV-A16, CV-A6, CV-A7, CV-B3, enterovirus A71 (EV-A71), EV-A89, EV-D68, and echovirus 6. With further investigation, the results indicated that 4'-FlU directly interacted with the RNA-dependent RNA polymerase of enterovirus, the 3D pol, and impaired the polymerase activity of 3D pol, hence inhibiting viral RNA synthesis and significantly suppressing viral replication. Our findings suggest that 4'-FlU could be promisingly developed as a broad-spectrum direct-acting antiviral agent for anti-enteroviruses therapy.

A cysteine protease inhibitor GC376 displays potent antiviral activity against coxsackievirus infection

Infection with coxsackievirus A10 (CV-A10) can cause hand-foot-mouth disease and is also associated with severe complications, including viral pneumonia, aseptic and viral meningitis. Coxsackievirus infection may also play a role in the pathogenesis of acute myocardial infarction and in the increased risk of type 1 diabetes mellitus in adults. However, there are no approved vaccines or direct antiviral agents available to prevention or treatment of coxsackievirus infection. Here, we reported that GC376 potently inhibited CV-A10 infection in different cell lines without cytotoxicity, significantly suppressed production of viral proteins, and strongly reduced the yields of infectious progeny virions. Further study indicated that GC376, as viral 3C protease inhibitor, had the potential to restrain the cleavage of the viral polyprotein into individually functional proteins, thus suppressed the replication of CV-A10. Furthermore, the drug exhibited antiviral activity against coxsackieviruses of various serotypes including CV-A6, CV-A7 and CV-A16, suggesting that GC376 is a broad-spectrum anti-coxsackievirus inhibitor and the 3C protease is a promising target for developing anti-coxsackievirus agents.

Montelukast as a potential treatment for COVID-19

INTRODUCTION

Montelukast is a leukotriene inhibitor that is widely used to treat chronic asthma and allergic rhinitis. The drug interferes with molecular signaling pathways produced by leukotrienes in a variety of cells and tissues throughout the human body that lead to tightening of airway muscles, production of aberrant pulmonary fluid (airway edema), and in some cases, pulmonary inflammation.

AREAS COVERED

Montelukast has also been noted to have anti-inflammatory properties, suggesting it may have a role in the treatment of coronavirus disease 2019 (COVID-19), the disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has been noted to induce misfiring of the immune system in some patients. A literature search of PubMed was performed to identify all relevant studies of montelukast and SARS-CoV-2 through 27 January 2023.

EXPERT OPINION

Montelukast has been the subject of small studies of SARS-CoV-2 and will be included in a large, randomized, double-blind, placebo-controlled study of outpatients with COVID-19 sponsored by the United States National Institutes of Health known as Accelerating COVID-19 Therapeutic Interventions and Vaccines-6. This paper reviews what is known about montelukast, an inexpensive, well-tolerated, and widely available medication, and examines the rationale for using this drug to potentially treat patients with COVID-19.

Leukotrienes in Innate Immunity: Still Underappreciated after All These Years?

Leukotrienes (LTs) are lipid mediators derived from the 5-lipoxygenase pathway of arachidonate metabolism. Though best known for their role in asthma, they have broad actions that touch on virtually every aspect of mammalian biology. In a Brief Review published in the journal in 2005, we presented the existing evidence supporting a role for LTs in host defense. In this updated Brief Review, we focus on selected advances since then. We detail new insights into mechanisms and regulation of LT biosynthesis; the protective roles of LTs in the host response to diverse classes of pathogens, with an emphasis on viruses, including SARS-CoV-2; the phagocyte signal transduction mechanisms by which LTs exert their antimicrobial actions; the capacity for overexuberant LT production to promote tissue damage; and roles of LTs in the noninfectious immune-relevant conditions neuroinflammation and cancer.

Acriflavine and proflavine hemisulfate as potential antivirals by targeting Mpro

The evolving SARS-CoV-2 epidemic buffets the world, and the concerted efforts are needed to explore effective drugs. M^pro is an intriguing antiviral target for interfering with viral RNA replication and transcription. In order to get potential anti-SARS-CoV-2 agents, we established an enzymatic assay using a fluorogenic substrate to screen the inhibitors of M^pro. Fortunately, Acriflavine (ACF) and Proflavine Hemisulfate (PRF) with the same acridine scaffold were picked out for their good inhibitory activity against M^pro with IC₅₀ of 5.60 ± 0.29 μM and 2.07 ± 0.01 μM, respectively. Further evaluation of MST assay and enzymatic kinetics experiment in vitro showed that they had a certain affinity to SARS-CoV-2 M^pro and were both non-competitive inhibitors. In addition, they inhibited about 90 % HCoV-OC43 replication in BHK-21 cells at 1 μM. Both compounds showed nano-molar activities against SARS-CoV-2 virus, which were superior to GC376 for anti-HCoV-43, and equivalent to the standard molecule remdesivir. Our study demonstrated that ACF and PRF were inhibitors of M^pro, and ACF has been previously reported as a PL^pro inhibitor. Taken together, ACF and PRF might be dual-targeted inhibitors to provide protection against infections of coronaviruses.