Anti-Influenza Treatment: Drugs Currently Used and Under Development

Anti-viral and Anti-inflammatory Isoflavonoids from Ukrainian Iris aphylla Rhizomes: Structure-Activity Relationship Coupled with ChemGPS-NP Analysis

Dried Iris rhizomes have been used in Chinese and European traditional medicine for the treatment of various diseases such as bacterial infections, cancer, and inflammation, as well as for being astringent, laxative, and diuretic agents. Eighteen phenolic compounds including some rare secondary metabolites, such as irisolidone, kikkalidone, irigenin, irisolone, germanaism B, kaempferol, and xanthone mangiferin, were isolated for the first time from Iris aphylla rhizomes. The hydroethanolic Iris aphylla extract and some of its isolated constituents showed protective effects against influenza H1N1 and enterovirus D68 and anti-inflammatory activity in human neutrophils. The promising anti-influenza effect of apigenin (13: , almost 100% inhibition at 50 µM), kaempferol (14: , 92%), and quercetin (15: , 48%) were further confirmed by neuraminidase inhibitory assay. Irisolidone (1: , almost 100% inhibition at 50 µM), kikkalidone (5: , 93%), and kaempferol (14: , 83%) showed promising anti-enterovirus D68 activity in vitro. The identified compounds were plotted using ChemGPS-NP to correlate the observed activity of the isolated phenolic compounds with the in-house database of anti-influenza and anti-enterovirus agents. Our results indicated that the hydroethanolic Iris aphylla extract and Iris phenolics hold the potential to be developed for the management of seasonal pandemics of influenza and enterovirus infections.

Enhancing neutralizing activity against influenza H1N1/PR8 by engineering a single-domain VL-M2 specific into a bivalent form

Flu disease, with high mortality and morbidity, is caused by the influenza virus. Influenza infections are most effectively prevented through vaccination, but it requires annual reformulation due to the antigenic shift or drift of hemagglutinin and neuraminidase proteins. Increasing resistance to available anti-influenza drugs was also recently reported. The M2 surface protein of the influenza virus is an attractive target for universal vaccine development as it is highly conserved and multifunctional throughout the viral life cycle. This study aimed to discover a single-chain variable fragment (scFv) targeting the M2 protein of influenza A H1N1/PR8, showing neutralizing activity through plaque inhibition in virus replication. Several candidates were isolated using bio-panning, including scFv and single-domain V_L target M2 protein, which was displayed on the yeast surface. The scFv/V_L proteins were obtained with high yield and high purity through soluble expression in E. coli BL21 (DE3) pLysE strains. A single-domain V_L-M2-specific antibody, NVLM10, exhibited the highest binding affinity to influenza virions and was engineered into a bivalent format (NVL2M10) to improve antigen binding. Both antibodies inhibited virus replication in a dose-dependent manner, determined using plaque reduction- and immunocytochemistry assays. Furthermore, bivalent anti-M2 single-domain V_L antibodies significantly reduced the plaque number and viral HA protein intensity as well as viral genome (HA and NP) compared to the monovalent single-domain V_L antibodies. This suggests that mono- or bivalent single-domain V_L antibodies can exhibit neutralizing activity against influenza virus A, as determined through binding to virus particle activity.

Design, synthesis, and biological activity of a novel series of 2-ureidonicotinamide derivatives against influenza A virus

BACKGROUND

Viral resistance to existing inhibitors and the time-dependent effectiveness of neuraminidase inhibitors have limited the number of antivirals that can be used for prophylaxis and therapeutic treatment of severe influenza infection. Thus, there is an urgent need to develop new drugs to prevent and treat influenza infection.

OBJECTIVE

The aim of this study was to design and synthesize a novel series of 2-ureidonicotinamide derivatives, and evaluate their anti-IAV activities. Furthermore, we predicted the abilities of these compounds inhibiting PA-PB1 subunit and forecasted the docking poses of these compounds with RNA polymerase protein (PDB ID 3CM8).

METHOD

The novel designed compounds were synthesized using classical methods of organic chemistry and tested in vitro for their abilities inhibiting RNP and against influenza A virus. In addition, the 23 synthesized molecules were subjected to the generated pharmacophore Hypo1 to forecast the activity target PA-PB1 subunit of RNA polymerase. The ADMET pharmacokinetic parameters were calculated by the ADMET modules in Discovery Studio 2016. The docking results helped us to demonstrate the possible interactions between these compounds with 3CM8.

RESULTS

The synthesized 2-ureidonicotinamide derivatives were characterized as potent anti-influenza inhibitors. The target compounds 7b and 7c demonstrated significant antiviral activities, and could be considered as novel lead compounds of antiviral inhibitors. In addition, compound 7b revealed suitable ADME properties expressed, and might be a significant RNA polymerase inhibitor targeting PA-PB1 subunit based on the predictable results and the docking results.

CONCLUSION

This study revealed a novel series of compounds that might be useful in the search for an effective drug against influenza virus.

Targeting the Host Response: Can We Manipulate Extracellular Matrix Metalloproteinase Activity to Improve Influenza Virus Infection Outcomes?

Each year, hundreds of thousands of individuals succumb to influenza virus infection and its associated complications. Several preventative and therapeutic options may be applied in order to preserve life. These traditional approaches include administration of seasonal influenza vaccines, pharmacological interventions in the form of antiviral drug therapy and supportive clinical approaches including mechanical ventilation and extracorporeal membrane oxygenation. While these measures have shown varying degrees of success, antiviral therapies and vaccination are constrained due to ongoing antigenic drift. Moreover, clinical approaches can also be associated with complications and drawbacks. These factors have led to the exploration and development of more sophisticated and nuanced therapeutic approaches involving host proteins. Advances in immunotherapy in the cancer field or administration of steroids following virus infection have highlighted the therapeutic potential of targeting host immune responses. We have now reached a point where we can consider the contribution of other “non-traditional” host components such as the extracellular matrix in immunity. Herein, we will review current, established therapeutic interventions and consider novel therapeutic approaches involving the extracellular matrix.

Na+/K+-ATPase as a Target of Cardiac Glycosides for the Treatment of SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), identified for the first time in Wuhan, China, causes coronavirus disease 2019 (COVID-19), which moved from epidemic status to becoming a pandemic. Since its discovery in December 2019, there have been countless cases of mortality and morbidity due to this virus. Several compounds such as chloroquine, hydroxychloroquine, lopinavir-ritonavir, and remdesivir have been tested as potential therapies; however, no effective treatment is currently recommended by regulatory agencies. Some studies on respiratory non-enveloped viruses such as adenoviruses and rhinovirus and some respiratory enveloped viruses including human respiratory syncytial viruses, influenza A, parainfluenza, SARS-CoV, and SARS-CoV-2 have shown the antiviral activity of cardiac glycosides, correlating their effect with Na⁺/K⁺-ATPase (NKA) modulation. Cardiac glycosides are secondary metabolites used to treat patients with cardiac insufficiency because they are the most potent inotropic agents. The effects of cardiac glycosides on NKA are dependent on cell type, exposure time, and drug concentration. They may also cause blockage of Na⁺ and K⁺ ionic transport or trigger signaling pathways. The antiviral activity of cardiac glycosides is related to cell signaling activation through NKA inhibition. Nuclear factor kappa B (NFκB) seems to be an essential transcription factor for SARS-CoV-2 infection. NFκB inhibition by cardiac glycosides interferes directly with SARS-CoV-2 yield and inflammatory cytokine production. Interestingly, the antiviral effect of cardiac glycosides is associated with tyrosine kinase (Src) activation, and NFκB appears to be regulated by Src. Src is one of the main signaling targets of the NKA α-subunit, modulating other signaling factors that may also impair viral infection. These data suggest that Src-NFκB signaling modulated by NKA plays a crucial role in the inhibition of SARS-CoV-2 infection. Herein, we discuss the antiviral effects of cardiac glycosides on different respiratory viruses, SARS-CoV-2 pathology, cell signaling pathways, and NKA as a possible molecular target for the treatment of COVID-19.

Computational gene expression profiling in the exploration of biomarkers, non-coding functional RNAs and drug perturbagens for COVID-19

The coronavirus disease, caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is a global health crisis that is being endured with an increased alarm of transmission each day. Though the pandemic has activated innumerable research attention to decipher an antidote, fundamental understanding of the molecular mechanisms is necessary to halt the disease progression. The study focused on comparison of the COVID-19 infected lung tissue gene expression datasets -GSE155241 and GSE150316 with the GEO2R-limma package. The significant up- and downregulated genes were annotated. Further evaluation of the enriched pathways, transcription factors, kinases, noncoding RNAs and drug perturbations revealed the significant molecular mechanisms of the host response. The results revealed a surge in mitochondrial respiration, cytokines, neurodegenerative mechanisms and deprived oxygen, iron, copper, and glucose transport. Hijack of ubiquitination by SARS-CoV-2, hox gene differentiation, histone modification, and miRNA biogenesis were the notable molecular mechanisms inferred. Long non-coding RNAs such as C058791.1, TTTY15 and TPTEP1 were predicted to be efficient in regulating the disease mechanisms. Drugs-F-1566-0341, Digoxin, Proscillaridin and Linifanib that reverse the gene expression signatures were predicted from drug perturbations analysis. The binding efficiency and interaction of proscillaridin and digoxin as obtained from the molecular docking studies confirmed their therapeutic potential. Two overlapping upregulated genes MDH1, SGCE and one downregulated gene PFKFB3 were appraised as potential biomarkers candidates. The upregulation of PGM5, ISLR and ANK2 as measured from their expressions in normal lungs affirmed their possible prognostic biomarker competence. The study explored significant insights for better diagnosis, and therapeutic options for COVID-19.

Communicated by Ramaswamy H. Sarma

Targeting Metalloenzymes for Therapeutic Intervention

Metalloenzymes are central to a wide range of essential biological activities, including nucleic acid modification, protein degradation, and many others. The role of metalloenzymes in these processes also makes them central for the progression of many diseases and, as such, makes metalloenzymes attractive targets for therapeutic intervention. Increasing awareness of the role metalloenzymes play in disease and their importance as a class of targets has amplified interest in the development of new strategies to develop inhibitors and ultimately useful drugs. In this Review, we provide a broad overview of several drug discovery efforts focused on metalloenzymes and attempt to map out the current landscape of high-value metalloenzyme targets.

Inhibitors of Influenza Virus Polymerase Acidic (PA) Endonuclease: Contemporary Developments and Perspectives

Influenza virus (IFV) causes periodic global influenza pandemics, resulting in substantial socioeconomic loss and burden on medical facilities. Yearly variation in the effectiveness of vaccines, slow responsiveness to vaccination in cases of pandemic IFV, and emerging resistance to available drugs highlight the need to develop additional small-molecular inhibitors that act on IFV proteins. One promising target is polymerase acidic (PA) endonuclease, which is a bridged dinuclear metalloenzyme that plays a crucial role in initiating IFV replication. During the past decade, intensive efforts have been made to develop small-molecular inhibitors of this endonuclease as candidate agents for treatment of IFV infection. Here, we review the current status of development of PA endonuclease inhibitors and we discuss the applicability of newer medicinal-chemistry strategies for the discovery more potent, selective, and safer inhibitors.