Effect of polyphenols against complications of COVID-19: current evidence and potential efficacy

The COVID-19 pandemic that started in 2019 and resulted in significant morbidity and mortality continues to be a significant global health challenge, characterized by inflammation, oxidative stress, and immune system dysfunction.. Developing therapies for preventing or treating COVID-19 remains an important goal for pharmacology and drug development research. Polyphenols are effective against various viral infections and can be extracted and isolated from plants without losing their therapeutic potential. Researchers have developed methods for separating and isolating polyphenols from complex matrices. Polyphenols are effective in treating common viral infections, including COVID-19, and can also boost immunity. Polyphenolic-based antiviral medications can mitigate SARS-CoV-2 enzymes vital to virus replication and infection. Individual polyphenolic triterpenoids, flavonoids, anthraquinonoids, and tannins may also inhibit the SARS-CoV-2 protease. Polyphenol pharmacophore structures identified to date can explain their action and lead to the design of novel anti-COVID-19 compounds. Polyphenol-containing mixtures offer the advantages of a well-recognized safety profile with few known severe side effects. However, studies to date are limited, and further animal studies and randomized controlled trials are needed in future studies. The purpose of this study was to review and present the latest findings on the therapeutic impact of plant-derived polyphenols on COVID-19 infection and its complications. Exploring alternative approaches to traditional therapies could aid in developing novel drugs and remedies against coronavirus infection.

SARS-CoV-2 and innate immunity: the good, the bad, and the "goldilocks"

An ancient conflict between hosts and pathogens has driven the innate and adaptive arms of immunity. Knowledge about this interplay can not only help us identify biological mechanisms but also reveal pathogen vulnerabilities that can be leveraged therapeutically. The humoral response to SARS-CoV-2 infection has been the focus of intense research, and the role of the innate immune system has received significantly less attention. Here, we review current knowledge of the innate immune response to SARS-CoV-2 infection and the various means SARS-CoV-2 employs to evade innate defense systems. We also consider the role of innate immunity in SARS-CoV-2 vaccines and in the phenomenon of long COVID.

Emergence and Reemergence of Human Coronaviruses: Spike Protein as the Potential Molecular Switch and Pharmaceutical Target

BACKGROUND

Recent emergence of COVID-19 caused by a new human coronavirus (CoV) strain (SARS-CoV2), which originated from the China, poses future emergence of additional CoVs. In most of the cases of emergence of human CoVs bats, palm civets, raccoon dogs and camels have been identified as the sources of human infections and reservoir hosts. A review of comparative genomic and phenotypic characteristics of human CoV strains vis-à-vis their comparison with the corresponding animal isolates shall provide the clues regarding the potential genomic, phenotypic and molecular factors responsible for host-switching, which may lead to prospective emergence and reemergence of human CoV outbreaks in future.

METHODS

The seven known human strains of CoV were analyzed for the host and viral factors responsible for human outbreaks. The molecular factors responsible for host-susceptibility, virulence and pathogenesis were reviewed to predict emergence and re-emergence of additional human CoV strains. CoV spike protein was evaluated as a potential viral receptor for host switching and the target for pharmaceutical design.

RESULTS

Review of the factors associated with host-susceptibility, virulence and pathogenesis of seven known human CoV strains present significant possibilities for emergence of new CoV strain(s), leading to more human outbreaks. Continuous exposure of animals' handlers to the infected animals, environmental changes, improper sanitations, nondisposal of the solid waste and resumption of exotic animals markets provide favorable conditions for "host switching" and emergence of new and potentially more virulent human CoV strains. Mutations in target genes (like spike protein), which facilitate the viral entry into the host-cells, provide potential "molecular switch" for preferences of new hostreceptors, genetic diversity, genetic-recombination and high virulence. Additionally, the clinical and environmental factors, asymptomatic carriers, paucity of efficacious vaccines & therapeutics, inefficient disease management and infection control measures, lack of public awareness, and effective communication of information about more virulent human-adapted virus isolates are critical factors for emergence of new and virulent SARS-CoV strains with high mortality and varied incubation period in the near future. Small molecules binding with conserved druggable regions of the CoV spike proteins may be effective against multiple strains of CoVs.

CONCLUSIONS

High propensity of mutations and "molecular adaptations" in coronaviruses create the hot spots and high potential for "host switching" leading to emergence of more virulent strains human CoVs. The public/global health agencies, medical communities and research scientists should be prepared for emergence and reemergence of new human CoV strain(s) leading to potential disease outbreaks. The inhibitors binding with conserved druggable regions of spike proteins from multiple strains CoV may have utility as broad-spectrum antiviral drugs to combat future emergence of CoVs.

Approaches and advances in the development of potential therapeutic targets and antiviral agents for the management of SARS-CoV-2 infection

Virus onslaughts continue to spread fear and cause rampage across the world every now and then. The twenty first century is yet again witnessing a gross global pandemic, Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Globally no vaccines or drug specific to COVID-19 is available. Corona viruses have been in mutual relationship with humans and other hosts over many decades though aggressive zoonotic strains have caused havoc. Zoonotic emergent corona viruses prior to SARS-COV-2 included severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), with the former leading to aggressive infectious spread and the later with high mortality rate. Although they emerged in the early period of the twenty first century, resilient biomedical and expertise in pharmaceutical domain could not appropriate any proprietary therapeutics. Studies envisaged towards curtailing their spread employed different stages of the virus life cycle with all zoonotic coronaviruses (CoVs) sharing genomic and structural similarities. Hence the strategies against SARS-CoV and MERS-CoV could prove effective against the recent outbreak of SAR-CoV-2. The review unravels key events involved in the lifecycle of SARS-CoV-2 while highlighting the possible avenues of therapy. The review also holds the scope in better understanding a broad-spectrum antivirals, monoclonal antibodies and small molecule inhibitors against viral glycoproteins, host cell receptor, viral mRNA synthesis, RNA-dependent RNA polymerase (RdRp) and viral proteases in order to design and develop antiviral drugs for SARS-CoV-2.

Accessing biological actions of Ganoderma secondary metabolites by in silico profiling

The species complex around the medicinal fungus Ganoderma lucidum Karst. (Ganodermataceae) is widely known in traditional medicines, as well as in modern applications such as functional food or nutraceuticals. A considerable number of publications reflects its abundance and variety in biological actions either provoked by primary metabolites, such as polysaccharides, or secondary metabolites, such as lanostane-type triterpenes. However, due to this remarkable amount of information, a rationalization of the individual Ganoderma constituents to biological actions on a molecular level is quite challenging. To overcome this issue, a database was generated containing meta-information, i.e., chemical structures and biological actions of hitherto identified Ganoderma constituents (279). This was followed by a computational approach subjecting this 3D multi-conformational molecular dataset to in silico parallel screening against an in-house collection of validated structure- and ligand-based 3D pharmacophore models. The predictive power of the evaluated in silico tools and hints from traditional application fields served as criteria for the model selection. Thus, the focus was laid on representative druggable targets in the field of viral infections (5) and diseases related to the metabolic syndrome (22). The results obtained from this in silico approach were compared to bioactivity data available from the literature. 89 and 197 Ganoderma compounds were predicted as ligands of at least one of the selected pharmacological targets in the antiviral and the metabolic syndrome screening, respectively. Among them only a minority of individual compounds (around 10%) has ever been investigated on these targets or for the associated biological activity. Accordingly, this study discloses putative ligand target interactions for a plethora of Ganoderma constituents in the empirically manifested field of viral diseases and metabolic syndrome which serve as a basis for future applications to access yet undiscovered biological actions of Ganoderma secondary metabolites on a molecular level.

Norovirus: targets and tools in antiviral drug discovery

The development of antiviral strategies to treat or prevent norovirus infections is a pressing matter. Noroviruses are the number 1 cause of acute gastroenteritis, of foodborne illness, of sporadic gastroenteritis in all age groups and of severe acute gastroenteritis in children less than 5 years old seeking medical assistance [USA/CDC]. In developing countries, noroviruses are linked to significant mortality (~200,000 children <5 years old). Noroviruses are a major culprit for the closure of hospital wards, and associated with increased hospitalization and mortality among the elderly. Transplant patients have significant risk of acquiring persistent norovirus gastroenteritis. Control and prevention strategies are limited to the use of disinfectants and hand sanitizers, whose efficacy is frequently insufficient. Hence, there is an ample need for antiviral treatment and prophylaxis of norovirus infections. The fact that only a handful of inhibitors of norovirus replication have been reported can largely be attributable to the hampering inability to cultivate human noroviruses in cell culture. The Norwalk replicon-bearing cells and the murine norovirus-infected cell lines are the available models to assess in vitro antiviral activity of compounds. Human noroviruses have been shown to replicate (to some extent) in mice, calves, gnotobiotic pigs, and chimpanzees. Infection of interferon-deficient mice with the murine norovirus results in virus-induced diarrhea. Here we review recent developments in understanding which norovirus proteins or host cell factors may serve as targets for inhibition of viral replication. Given the recent advances, significant progress in the search for antiviral strategies against norovirus infections is expected in the upcoming years.

Profiling of the kinome of cytomegalovirus-infected cells reveals the functional importance of host kinases Aurora A, ABL and AMPK

Human cytomegalovirus infection can lead to life-threatening clinical manifestations particularly in the immunocompromised host. Current therapy options face severe limitations leading to a continued search for alternative drug candidates. Viral replication is dependent on a balanced interaction between viral and cellular proteins. Especially protein kinases are important regulators of virus-host interaction indicated by remarkable kinome alterations induced upon HCMV infection. Here we report a novel approach of kinome profiling with an outcome that suggests an important role of specific cellular protein kinases, such as AMPK, ABL2 and Aurora A. Inhibition of AMPK and ABL kinases showed a significant reduction, whereas inhibition of Aurora A kinase led to a slight activation of HCMV replication, as measured in a GFP reporter-based replication assay. Furthermore, analysis of the mode of antiviral action suggested a substantial benefit for the efficiency of viral replication at the immediate early (AMPK) or early-late (ABL) phases of HCMV gene expression. In contrast, inhibition of Aurora A kinase promoted an enhancement of viral early-late gene expression, suggesting a putative role of Aurora A signaling in host defense. Thus, the combined data provide new information on host cell kinases involved in viral replication and uncovered potential targets for future antiviral strategies.