Development of effective anti-influenza drugs: congeners and conjugates - a review

Therapeutic effect of Yinhuapinggan granules mediated through the intestinal flora in mice infected with the H1N1 influenza virus

Objective

In this study, we examined the therapeutic effects of Yinhuapinggan granules (YHPGs) in influenza-infected mice. We also examined how YHPGs affect the composition of the intestinal flora and associated metabolites.

Methods

We used the nasal drip method to administer the influenza A virus (IAV) H1N1 to ICR mice. Following successful model construction, the mice were injected with 0.9% sterile saline and low (5.5 g/kg), medium (11 g/kg), and high (22 g/kg) doses of YHPGs. The pathological changes in the lungs and intestines were evaluated by gavage for 5 consecutive days. Detection of sIgA, IL-6, TNF-α, INF-γ, and TGF-β cytokine levels in serum by enzyme-linked immunosorbent assay. Real-time fluorescence quantitative polymerase chain reaction and Western blot were used to measure the mRNA and protein expression of the tight junction proteins claudin-1, occludin, and zonula occludens-1 (ZO-1) in the colon. To assess the influence of YHPGs on the intestinal microbiota, feces were obtained from the mice for 16s rRNA sequencing, and short-chain fatty acids (SCFAs) were measured in the feces.

Results

By reducing the production of pro-inflammatory cytokines and increasing the relative expression of claudin-1, occludin, and ZO-1 in colon tissues, YHPGs had a protective effect in tissues from the lungs and colon. When YHPGs were administered to mice with IAV infection, the relative abundance of Lactobacillus, Coprobacillus, Akkermansia, Prevotella, Oscillospira, and Ruminococcus increased, whereas the relative abundance of Desulfovibrio decreased.

Conclusion

The therapeutic mechanism of YHPGs against IAV infection in mice may be underpinned by modulation of the structural composition of colonic bacteria and regulation of SCFA production.

Synthesis and antimicrobial properties of guanidine-functionalized labdane type diterpenoids

The occurrence of increased antibiotic resistance has reduced the availability of drugs effective in the control of infectious diseases, especially those caused by various combinations of bacteria and/or fungi that are often associated with poorer patient outcomes. In the hunt for novel antibiotics of interest to treat polymicrobial diseases, molecules bearing guanidine moieties have recently come to the fore in designing and optimizing antimicrobial agents. Due to their remarkable antibacterial and antifungal activities, labdane diterpenes are also attracting increasing interest in antimicrobial drug discovery. In this study, six different guanidines prenylated with labdanic fragments were synthesized and evaluated for their antimicrobial properties. Assays were carried out against both non-resistant and antibiotic-resistant bacteria strains, while their possible antifungal activities have been tested on the yeast Candida albicans. Two of the synthesized compounds, namely labdan-8,13(R)-epoxy-15-oyl guanidine and labdan-8,13(S)-epoxy-15-oyl guanidine, were finally selected as the best candidates for further developments in drug discovery, due to their antimicrobial effects on both Gram-negative and Gram-positive bacterial strains, their fungicide action, and their moderate toxicity in vivo on zebrafish embryos. The study also provides insights into the structure-activity relationships of the guanidine-functionalized labdane-type diterpenoids.

Clinical efficacy, pharmacodynamic components, and molecular mechanisms of antiviral granules in the treatment of influenza: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

The Antiviral Granules (AG) are derived from the classical famous prescription, which is composed of 9 traditional Chinese medicines, namely Radix Isatidis (called Banlangen, BLG in Chinese), Forsythiae Fructus (called Lianqiao, LQ in Chinese), Gypsum fibrosum, Anemarrhenae Rhizoma (called Zhimu, ZM in Chinese), Phragmitis Rhizoma (called Lugen, LG in Chinese), Rehmanniae Radix (called Dihuang, DH in Chinese), Pogostemonis Herba (called Guanghuoxiang, GHX in Chinese), Acori Tatarinowii Rhizoma (called Shichangpu, SCP in Chinese), and Curcumae Radix (called Yujin, YJ in Chinese), and has shown an excellent therapeutic effect in clinical treatment of influenza. However, there are few studies on the anti-influenza mechanism of AG, and the mechanism of action is still unclear.

AIM OF THE STUDY

The purpose is to provide the latest information about the clinical efficacy, pharmacodynamic composition and mechanism of AG based on scientific literature, so as to enhance the utilization of AG in the treatment of influenza and related diseases, and promote the development and innovation of novel anti-influenza drugs targeting the influenza virus.

MATERIALS AND METHODS

Enter the data retrieval room, search for Antiviral Granules, as well as the scientific names, common names, and Chinese names of each Chinese medicine. Additionally, search for the relevant clinical applications, pharmacodynamic composition, pharmacological action, and molecular mechanism of both Antiviral Granules and single-ingredient medicines. Keywords includes terms such as "antiviral granules", "influenza", "Isatis indigotica Fort.", "Radix Isatidis", "Banlangeng", "pharmacology", "clinical application", "pharmacologic action", etc. and their combinations. Obtain results from the Web of Science, PubMed, Google Scholar, Sci Finder Scholar, CNKI and other resources.

RESULTS

AG is effective in the treatment of influenza and is often used in combination with other drugs to treat viral diseases. Its chemical composition is complex, including alkaloids, polysaccharides, volatile oils, steroid saponins, phenylpropanoids, terpenoids and other compounds. These compounds have a variety of pharmacological activities, which can interfere with the replication cycle of the influenza virus, regulate RIG-I-MAVS, JAK/STAT, TLRs/MyD88, NF-κB signaling pathways and related cytokines, regulate intestinal microorganisms, and protect both the lungs and extrapulmonary organs.

CONCLUSIONS

AG can overcome the limitations of traditional antiviral drug therapy, play a synergistic role in fighting influenza virus with the characteristics of multi-component, multi-pathway and multi-target therapy, and reverse the bodily function damage caused by influenza virus. AG may be a potential drug in the prevention and treatment of influenza and related diseases.

Natural History of Influenza B Virus-Current Knowledge on Treatment, Resistance and Therapeutic Options

Influenza B virus (IBV) significantly impacts the health and the economy of the global population. WHO global health estimates project 1 billion flu cases annually, with 3 to 5 million resulting in severe disease and 0.3 to 0.5 million influenza-related deaths worldwide. Influenza B virus epidemics result in significant economic losses due to healthcare expenses, reduced workforce productivity, and strain on healthcare systems. Influenza B virus epidemics, such as the 1987-1988 Yamagata lineage outbreak and the 2001-2002 Victoria lineage outbreak, had a significant global impact. IBV's fast mutation and replication rates facilitate rapid adaptation to the environment, enabling the evasion of existing immunity and the development of resistance to virus-targeting treatments. This leads to annual outbreaks and necessitates the development of new vaccination formulations. This review aims to elucidate IBV's evolutionary genomic organization and life cycle and provide an overview of anti-IBV drugs, resistance, treatment options, and prospects for IBV biology, emphasizing challenges in preventing and treating IBV infection.

Evaluation of the Antiviral Activity of Tabamide A and Its Structural Derivatives against Influenza Virus

Influenza viruses cause severe endemic respiratory infections in both humans and animals worldwide. The emergence of drug-resistant viral strains requires the development of new influenza therapeutics. Tabamide A (TA0), a phenolic compound isolated from tobacco leaves, is known to have antiviral activity. We investigated whether synthetic TA0 and its derivatives exhibit anti-influenza virus activity. Analysis of structure-activity relationship revealed that two hydroxyl groups and a double bond between C7 and C8 in TA0 are crucial for maintaining its antiviral action. Among its derivatives, TA25 showed seven-fold higher activity than TA0. Administration of TA0 or TA25 effectively increased survival rate and reduced weight loss of virus-infected mice. TA25 appears to act early in the viral infection cycle by inhibiting viral mRNA synthesis on the template-negative strand. Thus, the anti-influenza virus activity of TA0 can be expanded by application of its synthetic derivatives, which may aid in the development of novel antiviral therapeutics.

Natural products as potential lead compounds to develop new antiviral drugs over the past decade

Virus infection has been one of the main causes of human death since the ancient times. Even though more and more antiviral drugs have been approved in clinic, long-term use can easily lead to the emergence of drug resistance and side effects. Fortunately, there are many kinds of metabolites which were produced by plants, marine organisms and microorganisms in nature with rich structural skeletons, and they are natural treasure house for people to find antiviral active substances. Aiming at many types of viruses that had caused serious harm to human health in recent years, this review summarizes the natural products with antiviral activity that had been reported for the first time in the past ten years, we also sort out the source, chemical structure and safety indicators in order to provide potential lead compounds for the research and development of new antiviral drugs.

Phillyrin ameliorates influenza a virus-induced pulmonary inflammation by antagonizing CXCR2 and inhibiting NLRP3 inflammasome activation

Influenza is an acute viral respiratory illness with high morbidity rates worldwide. Excessive pulmonary inflammation is the main characteristic of lethal influenza A virus (IAV) infections. Therapeutic options for managing influenza are limited to vaccines and some antiviral medications. Phillyrin is one of the major bioactive components of the Chinese herbal medicine Forsythia suspensa, which has the functions of sterilization, heat clearing and detoxification. In this work, the effect and mechanism of phillyrin on H1N1 influenza (PR8)-induced pneumonia were investigated. We reported that phillyrin (15 mg/kg) treatment after viral challenge significantly improved the weight loss, ameliorated pulmonary inflammation and inhibited the accumulation of multiple cytokines and chemokines in bronchoalveolar lavage fluid on 7 days post infection (dpi). In vitro, phillyrin suppressed influenza viral replication (Matrixprotein and nucleoprotein messenger RNA level) and reduced influenza virus-induced cytopathic effect (CPE). Furthermore,chemokine receptor CXCR2 was confirmed to be markedly inhibited by phillyrin. Surface plasmon resonance results reveal that phillyrin exhibits binding affinity to CXCR2, having a binding affinity constant (KD) value of 1.858e-5 M, suggesting that CXCR2 is a potential therapeutic target for phillyrin. Moreover, phillyrin inhibited the mRNA and protein expression levels of Caspase1, ASC and NLRP3 in the lungs of mice with H1N1-induced pneumonia.This study reveals that phillyrin ameliorates IAV-induced pulmonary inflammation by antagonizing CXCR2 and inhibiting NLRP3 inflammasome activation partly.

Antiviral and antimicrobial applications of chalcones and their derivatives: From nature to greener synthesis

Chalcones and their derivatives have been widely studied due to their versatile pharmacological and biological activities, such as anti-inflammatory, antibacterial, antiviral, and antitumor effects. These compounds have shown suitable antiviral effects through the selective targeting of a variety of viral enzymes, including lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fumarate reductase, protein tyrosine phosphatase, topoisomerase-II, protein kinases, integrase/protease, and lactate/isocitrate dehydrogenase, among others. Chalcones and their derivatives have displayed excellent potential for combating pathogenic bacteria and fungi (especially, multidrug-resistant bacteria). However, relevant mechanisms should be further explored, focusing on inhibitory effects against DNA gyrase B, UDP-N-acetylglucosamine enolpyruvyl transferase (MurA), and efflux pumps (e.g., NorA), among others. In addition, the antifungal and antiparasitic activities of these compounds (e.g., antitrypanosomal and antileishmanial properties) have prompted additional explorations. Nonetheless, systematic analysis of the relevant mechanisms, biosafety issues, and pharmacological properties, as well as clinical translation studies, are vital for practical applications. Herein, recent advancements pertaining to the antibacterial, antiviral, antiparasitic, and antifungal activities of chalcones and their derivatives are deliberated, focusing on the relevant mechanisms of action, crucial challenges, and future prospects. Furthermore, due to the great importance of greener and more sustainable synthesis of these valuable compounds, especially on an industrial scale, the progress made in this field has been briefly discussed. Hopefully, this review can serve as a catalyst for researchers to delve deeper into the exploration and designing of novel chalcone compounds with medicinal properties, especially against pathogenic viruses and multidrug-resistant bacteria as major causes of concern for human health.

Protein arginine methyltransferase 5 mediates arginine symmetric dimethylation of influenza A virus PB2 and supports viral replication

Influenza A virus (IAV) relies on intricate and highly coordinated associations with host factors for efficient replication and transmission. Characterization of such factors holds great significance for development of anti-IAV drugs. Our study identified protein arginine methyltransferase 5 (PRMT5) as a novel host factor indispensable for IAV replication. Silencing PRMT5 resulted in drastic repression of IAV replication. Our findings revealed that PRMT5 interacts with each protein component of viral ribonucleoproteins (vRNPs) and promotes arginine symmetric dimethylation of polymerase basic 2 (PB2). Overexpression of PRMT5 enhanced viral polymerase activity in a dose-dependent manner, emphasizing its role in genome transcription and replication of IAV. Moreover, analysis of PB2 protein sequences across various subtypes of IAVs demonstrated the high conservation of potential RG motifs recognized by PRMT5. Overall, our study suggests that PRMT5 supports IAV replication by facilitating viral polymerase activity by interacting with PB2 and promoting its arginine symmetric dimethylation. This study deepens our understanding of how IAV manipulates host factors to facilitate its replication and highlights the great potential of PRMT5 to serve as an anti-IAV therapeutic target.

Rational Design of Novel Peptidomimetics against Influenza A Virus: Biological and Computational Studies

Effective therapy against the influenza virus is still an unmet goal. Drugs with antiviral effects exist, but the appearance of resistant viruses pushes towards the discovery of drugs with different mechanisms of action. New anti-influenza molecules should target a good candidate, as a new anti-influenza molecule could be an inhibitor of the influenza A virus hemagglutinin (HA), which plays a key role during the early phases of infection. In previous work, we identified two tetrapeptide sequences, SLDC (1) and SKHS (2), derived from bovine lactoferrin (bLf) C-lobe fragment 418-429, which were able to bind HA and inhibit cell infection at picomolar concentration. Considering the above, the aim of this study was to synthesize a new library of peptidomimetics active against the influenza virus. In order to test their ability to bind HA, we carried out a preliminary screening using biophysical assays such as surface plasmon resonance (SPR) and orthogonal immobilization-free microscale thermophoresis (MST). Biological and computational studies on the most interesting compounds were carried out. The methods applied allowed for the identification of a N-methyl peptide, S(N-Me)LDC, which, through high affinity binding of influenza virus hemagglutinin, was able to inhibit virus-induced hemagglutination and cell infection at picomolar concentration. This small sequence, with high activity, represents a good starting point for the design of new peptidomimetics and small molecules.

An inhaled ACE2 decoy confers protection against SARS-CoV-2 infection in preclinical models

The Omicron variant continuously evolves under the humoral immune pressure exerted by vaccination and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and the resulting Omicron subvariants display further immune evasion and antibody escape. An engineered angiotensin-converting enzyme 2 (ACE2) decoy composed of high-affinity ACE2 and an IgG1 Fc domain could offer an alternative modality to neutralize SARS-CoV-2. We previously reported its broad spectrum and therapeutic potential in rodent models. Here, we demonstrate that the engineered ACE2 decoy retains neutralization activity against Omicron subvariants, including the currently emerging XBB and BQ.1 strains, which completely evade antibodies currently in clinical use. SARS-CoV-2, under the suboptimal concentration of neutralizing drugs, generated SARS-CoV-2 mutants escaping wild-type ACE2 decoy and monoclonal antibodies, whereas no escape mutant emerged against the engineered ACE2 decoy. Furthermore, inhalation of aerosolized decoys improved the outcomes of rodents infected with SARS-CoV-2 at a 20-fold lower dose than that of intravenous administration. Last, the engineered ACE2 decoy exhibited therapeutic efficacy for cynomolgus macaques infected with SARS-CoV-2. These results indicate that this engineered ACE2 decoy represents a promising therapeutic strategy to overcome immune-evading SARS-CoV-2 variants and that liquid aerosol inhalation could be considered as a noninvasive approach to enhance the efficacy of COVID-19 treatments.

Structural and Synthetic Aspects of Small Ring Oxa- and Aza-Heterocyclic Ring Systems as Antiviral Activities

Antiviral properties of different oxa- and aza-heterocycles are identified and properly correlated with their structural features and discussed in this review article. The primary objective is to explore the activity of such ring systems as antiviral agents, as well as their synthetic routes and biological significance. Eventually, the structure-activity relationship (SAR) of the heterocyclic compounds, along with their salient characteristics are exhibited to build a suitable platform for medicinal chemists and biotechnologists. The synergistic conclusions are extremely important for the introduction of a newer tool for the future drug discovery program.

SARS-CoV-2 Binding to Terminal Sialic Acid of Gangliosides Embedded in Lipid Membranes

Multiple recent reports indicate that the S protein of SARS-CoV-2 specifically interacts with membrane receptors and attachment factors other than ACE2. They likely have an active role in cellular attachment and entry of the virus. In this article, we examined the binding of SARS-CoV-2 particles to gangliosides embedded in supported lipid bilayers (SLBs), mimicking the cell membrane-like environment. We show that the virus specifically binds to sialylated (sialic acid (SIA)) gangliosides, i.e., GD1a, GM3, and GM1, as determined from the acquired single-particle fluorescence images using a time-lapse total internal reflection fluorescence (TIRF) microscope. The data of virus binding events, the apparent binding rate constant, and the maximum virus coverage on the ganglioside-rich SLBs show that the virus particles have a higher binding affinity toward the GD1a and GM3 compared to the GM1 ganglioside. Enzymatic hydrolysis of the SIA-Gal bond of the gangliosides confirms that the SIA sugar unit of GD1a and GM3 is essential for virus attachment to the SLBs and even the cell surface sialic acid is critical for the cellular attachment of the virus. The structural difference between GM3/GD1a and GM1 is the presence of SIA at the main or branched chain. We conclude that the number of SIA per ganglioside can weakly influence the initial binding rate of SARS-CoV-2 particles, whereas the terminal or more exposed SIA is critical for the virus binding to the gangliosides in SLBs.

Pyrrolo[2,3-e]indazole as a novel chemotype for both influenza A virus and pneumococcal neuraminidase inhibitors

Influenza infections are often exacerbated by secondary bacterial infections, primarily caused by Streptococcus pneumoniae. Both respiratory pathogens have neuraminidases that support infection. Therefore, we hypothesized that dual inhibitors of viral and bacterial neuraminidases might be an advantageous strategy for treating seasonal and pandemic influenza pneumonia complicated by bacterial infections. By screening our in-house chemical library, we discovered a new chemotype that may be of interest for a further campaign to find small molecules against influenza. Our exploration of the pyrrolo[2,3-e]indazole space led to the identification of two hit compounds, 6h and 12. These molecules were well-tolerated by MDCK cells and inhibited the replication of H3N2 and H1N1 influenza A virus strains. Moreover, both compounds suppress viral and pneumococcal neuraminidases indicating their dual activity. Given its antiviral activity, pyrrolo[2,3-e]indazole has been identified as a promising scaffold for the development of novel neuraminidase inhibitors that are active against influenza A virus and S. pneumoniae.

Massive bleeding from a duodenal ulcer in a child with influenza infection: A case report of endoscopic findings

Gastrointestinal bleeding or perforation following influenza infection is rare. We encountered a pediatric case of hemorrhagic duodenal ulcer following influenza A infection. The patient was a 1‐year and 4‐month‐old boy who was diagnosed with influenza A infection and treated with laninamivir octanoate. After inhalation, he had diarrhea, poor appetite, and melena. The next day, he had hematochezia and developed hemorrhagic shock. Contrast‐enhanced computed tomography showed extravasation in the descending part of the duodenum. Esophagogastroduodenoscopy revealed spurting bleeding from a Dieulafoy's lesion on the oral side of the major papilla, and he underwent hemostasis by clipping. From the bulb to the descending part of the duodenum, the mucosa appeared atrophic with spotty redness on the circular folds and multiple and irregularly shaped erosions. Almost all mucosal lesions had healed by the eighth day, and he was monitored as an outpatient for more than one year without re‐bleeding. Intestinal ischemia, viral invasion, and drug reaction of laninamivir octanoate may be involved in duodenal mucosal injury. Acute duodenal ulcers may occur in children with influenza infection, especially young children.

Knockout of Noxa with CRISPR/Cas9 Increases Host Resistance to Influenza Virus Infection

The influenza virus induces cellular apoptosis during viral propagation, and controlling this virus-induced apoptosis process has been shown to have significant antiviral effects. The proapoptotic BH3-only protein Noxa is a strong inducer of apoptosis that can be activated by this virus, suggesting that Noxa has the potential as an anti-influenza target. To assess the value of Noxa as an antiviral target, we utilized CRISPR/Cas9 technology to produce a Noxa-knockout cell line. We found that the knockout of Noxa resulted in a dramatic reduction in the cytopathic effect induced by the influenza virus. Moreover, Noxa knockout decreased the expression of influenza viral proteins (NP, M2, HA, and NS2). In addition, Noxa deficiency triggered a complete autophagic flux to weaken influenza virus-induced autophagosome accumulation, indicating that Noxa may be a promising antiviral target for controlling influenza virus infections.

Opportunistic etiological agents causing lung infections: emerging need to transform lung-targeted delivery

Lung diseases continue to draw considerable attention from biomedical and public health care agencies. The lung with the largest epithelial surface area is continuously exposed to the external environment during exchanging gas. Therefore, the chances of respiratory disorders and lung infections are overgrowing. This review has covered promising and opportunistic etiologic agents responsible for lung infections. These pathogens infect the lungs either directly or indirectly. However, it is difficult to intervene in lung diseases using available oral or parenteral antimicrobial formulations. Many pieces of research have been done in the last two decades to improve inhalable antimicrobial formulations. However, very few have been approved for human use. This review article discusses the approved inhalable antimicrobial agents (AMAs) and identifies why pulmonary delivery is explored. Additionally, the basic anatomy of the respiratory system linked with barriers to AMA delivery has been discussed here. This review opens several new scopes for researchers to work on pulmonary medicines for specific diseases and bring more respiratory medication to market.

Prophylaxis and Remediation for Future Pandemic Pathogens-(Lessons from a Post-COVID World)

Since influenza and coronaviruses are currently deadly and emerging threats worldwide, better treatment, remediation and prevention options are needed. In that regard, a basic understanding of severe acute respiratory syndrome (SARS)-CoV-2/COVID-19 (Betacoronaviridae) and other viral pathogen mechanisms of transmission are expected. Unfortunately, unprecedented, and growing distrust of vaccines and even masks or personal protective equipment (PPE) in the United States and elsewhere presents itself as an added challenge. We postulate that development of improved and highly effective prophylactic measures, together with new life-saving therapies that do inhibit or otherwise treat infection of SARS-CoV-2, influenza and other viral pathogens, could be an adjunct measure to globally protect vulnerable individuals from pandemic threats. In this review, we share what we learned from the past COVID experience to offer a multifactorial and improved approach to current and future pandemic infections or threats using low-cost means.

Microscale Quantification of the Inhibition of Neuraminidase Using Capillary Nanogel Electrophoresis

Neuraminidase inhibitors modulate infections that involve sialic acids, making quantitative analyses of this inhibitory effect important for selecting and designing potential therapeutics. An automated nanogel capillary electrophoresis system is developed that integrates a 5 nL enzyme inhibition reaction in line with a 5 min separation-based assay of the enzymatic product to quantify inhibition as the half maximal inhibitory concentration (IC50) and inhibitor constant (Ki). A neuraminidase enzyme from Clostridium perfringens is non-covalently immobilized in a thermally tunable nanogel positioned in the thermally controlled region of the capillary by increasing the capillary temperature to 37 °C. Aqueous inhibitor solutions are loaded into the capillary during the nanogel patterning step to surround the enzyme zone. The capillary electrophoresis separation provides a means to distinguish the de-sialylated product, enabling the use of sialyllactose which contains the trisaccharide motif observed on serine/threonine-linked (O-linked) glycans. A universal nanogel patterning scheme is developed that does not require pre-mixing of enzymes with inhibitors when an automated capillary electrophoresis instrument is used, thus reducing the consumption of enzymes and enabling adaption of the method to different inhibitors. The universal approach is successfully applied to two classical neuraminidase inhibitors with different electrophoretic mobilities. The IC50 and Ki values obtained for N-acetyl-2,3-dehydro-2-deoxyneuraminic acid (DANA) are 13 ± 3 and 5.0 ± 0.9 μM, respectively, and 28 ± 3 and 11 ± 1 μM, respectively, for Siastatin B. These values agree with literature reports and reflect the weaker inhibition anticipated for Siastatin B in comparison to DANA.

Antiviral Potential of Natural Resources against Influenza Virus Infections

Influenza is a severe contagious disease caused by influenza A and B viruses. The WHO estimates that annual outbreaks lead to 3-5 million severe infections of which approximately 10% lead to the death of the patient. While vaccination is the cornerstone of prevention, antiviral drugs represent the most important treatment option of acute infections. Only two classes of drugs are currently approved for the treatment of influenza in numerous countries: M2 channel blockers and neuraminidase inhibitors. In some countries, additional compounds such as the recently developed cap-dependent endonuclease inhibitor baloxavir marboxil or the polymerase inhibitor favipiravir are available. However, many of these compounds suffer from poor efficacy, if not applied early after infection. Furthermore, many influenza strains have developed resistances and lost susceptibility to these compounds. As a result, there is an urgent need to develop new anti-influenza drugs against a broad spectrum of subtypes. Natural products have made an important contribution to the development of new lead structures, particularly in the field of infectious diseases. Therefore, this article aims to review the research on the identification of novel lead structures isolated from natural resources suitable to treat influenza infections.

Evolution of Influenza Viruses-Drug Resistance, Treatment Options, and Prospects

Viral evolution refers to the genetic changes that a virus accumulates during its lifetime which can arise from adaptations in response to environmental changes or the immune response of the host. Influenza A virus is one of the most rapidly evolving microorganisms. Its genetic instability may lead to large changes in its biological properties, including changes in virulence, adaptation to new hosts, and even the emergence of infectious diseases with a previously unknown clinical course. Genetic variability makes it difficult to implement effective prophylactic programs, such as vaccinations, and may be responsible for resistance to antiviral drugs. The aim of the review was to describe the consequences of the variability of influenza viruses, mutations, and recombination, which allow viruses to overcome species barriers, causing epidemics and pandemics. Another consequence of influenza virus evolution is the risk of the resistance to antiviral drugs. Thus far, one class of drugs, M2 protein inhibitors, has been excluded from use because of mutations in strains isolated in many regions of the world from humans and animals. Therefore, the effectiveness of anti-influenza drugs should be continuously monitored in reference centers representing particular regions of the world as a part of epidemiological surveillance.

Identification of cytochrome c oxidase subunit 4 isoform 1 as a positive regulator of influenza virus replication

Human infection with highly pathogenic H5N1 influenza virus causes severe respiratory diseases. Currently, the drugs against H5N1 are limited to virus-targeted inhibitors. However, drug resistance caused by these inhibitors is becoming a serious threat to global public health. An alternative strategy to reduce the resistance risk is to develop antiviral drugs targeting host cell proteins. In this study, we demonstrated that cytochrome c oxidase subunit 4 isoform 1 (COX41) of host cell plays an important role in H5N1 infection. Overexpression of COX41 promoted viral replication, which was inhibited by silencing or knockout the expression of COX41 in the host cell. The ribonucleoproteins (RNPs) of H5N1 were retained in the cell nucleus after knockout cellular COX41. Strikingly, inhibition of cellular COX41 by lycorine, a small-molecule compound isolated from Amaryllidaceae plants, reduced the levels of COX41-induced ROS and phosphorylation of extracellular signal-regulated kinase (ERK) in cells, thus resulting in the blockage of nuclear export of vRNP and inhibition of viral replication. In H5N1-infected mice that were treated with lycorine, we observed a reduction of viral titers and inhibition of pathological changes in the lung and trachea tissues. Importantly, no resistant virus was generated after culturing the virus with the continuous treatment of lycorine. Collectively, these findings suggest that COX41 is a positive regulator of H5N1 replication and might serve as an alternative target for anti-influenza drug development.

DDX5: an expectable treater for viral infection- a literature review

Background and Objective

DEAD-box protein (DDX)5 plays important roles in multiple aspects of cellular processes that require modulating RNA structure. Alongside the canonical role of DDX5 in RNA metabolism, many reports have shown that DDX5 influences viral infection by directly interacting with viral proteins. However, the functional role of DDX5 in virus-associated cancers, as well as the identity of DDX5 in virus infection-associated signaling pathways, has remained largely unexplained. Here, we further explore the precise functions of DDX5 and its potential targets for antiviral treatment.

Methods

We searched the PubMed and PMC databases to identify studies on role of DDXs, especially DDX5, during various viral infection published up to May 2022.

Key Content and Findings

DDX5 functions as both a viral infection helper and inhibitor, which depends on virus type. DDXs proteins have been identified to play roles on multiple aspects covering RNA metabolism and function.

Conclusions

DDX5 influences viral pathogenesis by participating in viral replication and multiple viral infection-related signaling pathways, it also plays a double-edge sword role under different viral infection conditions. Deep investigation into the mechanism of DDX5 modulating immune response in host cells revealed that it holds highly potential usage for future antiviral therapy. We reviewed current studies to provide a comprehensive update of the role of DDX5 in viral infection.

Efficacy and safety of Qinxiang Qingjie oral solution for the treatment of influenza in children: a randomized, double-blind, multicenter clinical trial

BACKGROUND

Qinxiang Qingjie (QXQJ), an oral solution containing various Chinese herbs, is indicated for pediatric upper respiratory tract infections. The treatment of influenza also shows potential advantages in shortening the duration of illness and improving symptoms. However, there is still a lack of high-quality clinical evidence to support this. The trial was to explore the efficacy and safety of QXQJ for treating pediatric influenza and provide an evidence-based basis for expanding its applicability.

METHODS

A randomized, double-blind, double-dummy, positive-controlled, multicenter clinical trial was conducted in 14 hospitals in China. Children aged 1-13 years with influenza and "exterior and interior heat syndromes" as defined by traditional Chinese medicine (TCM) were randomly assigned to two groups with 1:1 radio. Children in the test group received QXQJ oral solution and oseltamivir simulant, while the control group received oseltamivir phosphate granules and QXQJ simulant. The duration of treatment was five days, followed by a two-day follow-up period. The primary endpoint was the clinical recovery time. Secondary endpoints included the time to defervescence, incidences of complications and severe or critical influenza, negative conversion rate, improvement of TCM syndromes, and safety profiles of the therapeutics, which mainly contained the adverse clinical events and adverse drug reactions.

RESULTS

A total of 231 children were randomized to either the QXQJ (n=117) or oseltamivir (n=114) group. The FAS and PPS results showed that both groups experienced a median clinical recovery time of three days (P>0.05). The median time to defervescence of both groups were 36 hours in FAS and PPS (P>0.05), and two groups did not differ in terms of the other secondary endpoints (P>0.05). 14 patients (12.39%) in the QXQJ group and 14 patients (12.50%) in the oseltamivir group reported at least one adverse event, respectively. One serious adverse event occurred in the QXQJ group. There was no significant difference in the incidence of adverse events or adverse drug reactions between the groups.

CONCLUSIONS

The efficacy of QXQJ oral solution was comparable to that of oseltamivir for treating influenza in children, with an acceptable safety profile.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR1900021060.

The Emerging Roles of Silver Nanoparticles to Target Viral Life Cycle and Detect Viral Pathogens

Along the line of recent vaccine advancements, new antiviral therapeutics are compelling to combat viral infection-related public health crises. Several properties of silver nanoparticles (AgNPs) such as low level of cytotoxicity, ease of tunability of the AgNPs in the ultra-small nanoscale size and shape through different convenient bottom-up chemistry approaches, high penetration of the composite with drug formulations into host cells has made AgNPs, a promising candidate for developing antivirals. In this review, we have highlighted the recent advancements in the AgNPs based nano-formulations to target cellular mechanisms of viral propagation, immune modulation of the host, and the ability to synergistically enhance the activity of existing antiviral drugs. On the other hand, we have discussed the recent advancements on AgNPs based detection of viral pathogens from clinical samples using inherent physicochemical properties. This article will provide an overview of our current knowledge on AgNPs based formulations that has promising potential for developing a counteractive strategy against emerging and existing viruses.

Treatment of Respiratory Viral Coinfections

With the advent of rapid multiplex PCR, physicians have been able to test for multiple viral pathogens when a patient presents with influenza-like illness. This has led to the discovery that many respiratory infections are caused by more than one virus. Antiviral treatment of viral coinfections can be complex because treatment of one virus will affect the time course of the other virus. Since effective antivirals are only available for some respiratory viruses, careful consideration needs to be given on the effect treating one virus will have on the dynamics of the other virus, which might not have available antiviral treatment. In this study, we use mathematical models of viral coinfections to assess the effect of antiviral treatment on coinfections. We examine the effect of the mechanism of action, relative growth rates of the viruses, and the assumptions underlying the interaction of the viruses. We find that high antiviral efficacy is needed to suppress both infections. If high doses of both antivirals are not achieved, then we run the risk of lengthening the duration of coinfection or even of allowing a suppressed virus to replicate to higher viral titers.

Optimization of an Inclusion Body-Based Production of the Influenza Virus Neuraminidase in Escherichia coli

Neuraminidase (NA), as an important protein of influenza virus, represents a promising target for the development of new antiviral agents for the treatment and prevention of influenza A and B. Bacterial host strain Escherichia coli BL21 (DE3)pLysS containing the NA gene of the H1N1 influenza virus produced this overexpressed enzyme in the insoluble fraction of cells in the form of inclusion bodies. The aim of this work was to investigate the effect of independent variables (propagation time, isopropyl β-d-1-thiogalactopyranoside (IPTG) concentration and expression time) on NA accumulation in inclusion bodies and to optimize these conditions by response surface methodology (RSM). The maximum yield of NA (112.97 ± 2.82 U/g) was achieved under optimal conditions, namely, a propagation time of 7.72 h, IPTG concentration of 1.82 mM and gene expression time of 7.35 h. This study demonstrated that bacterially expressed NA was enzymatically active.

Anomeric 1,2,3-triazole-linked sialic acid derivatives show selective inhibition towards a bacterial neuraminidase over a trypanosome trans-sialidase

Sialic acid is the natural substrate for sialidases and its chemical modification has been a useful approach to generate potent and selective inhibitors. Aiming at advancing the discovery of selective Trypanosoma cruzi trans-sialidase (TcTS) inhibitors, we have synthesised a small series of anomeric 1,2,3-triazole-linked sialic acid derivatives in good yields and high purity via copper-catalysed azide-alkyne cycloaddition (CuAAC, click chemistry) and evaluated their activity towards TcTS and neuraminidase. Surprisingly, the compounds showed practically no TcTS inhibition, whereas ca. 70% inhibition was observed for neuraminidase in relation to the analogues bearing hydrophobic substituents and ca. 5% for more polar substituents. These results suggest that polarity changes are less tolerated by neuraminidase due to the big difference in impact of hydrophobicity upon inhibition, thus indicating a simple approach to differentiate both enzymes. Moreover, such selectivity might be reasoned based on a possible steric hindrance caused by a bulky hydrophobic loop that sits over the TcTS active site and may prevent the hydrophobic inhibitors from binding. The present study is a step forward in exploiting subtle structural differences in sialidases that need to be addressed in order to achieve selective inhibition.

Multi-Target Approaches of Epigallocatechin-3-O-gallate (EGCG) and its Derivatives Against Influenza Viruses

Influenza viruses (INFV), Orthomyxoviridae family, are mainly transmitted among humans, via aerosols or droplets from the respiratory secretions. However, fomites could be a potential transmission pathway. Annually, seasonal INFV infections account for 290-650 thousand deaths worldwide. Currently, there are two classes of approved drugs to treat INFV infections, being neuraminidase (NA) inhibitors and blockers of matrix-2 (M2) ion channel. However, cases of resistance have been observed for both chemical classes, reducing the efficacy of treatment. The emergence of influenza outbreaks and pandemics calls for new antiviral molecules more effective and that could overcome the current resistance to anti-influenza drugs. In this context, polyphenolic compounds are found in various plants and these have displayed different multi-target approaches against diverse pathogens. Among these, green tea (Camellia sinensis) catechins, in special epigallocatechin-3-O-gallate (EGCG), have demonstrated significant activities against the two most relevant human INFV, subtypes A and lineages B. In this sense, EGCG has been found a promising multi-target agent against INFV since can act inhibiting NA, hemagglutination (HA), RNA-dependent RNA polymerase (RdRp), and viral entry/adsorption. In general, the lack of knowledge about potential multi-target natural products prevents an adequate exploration of them, increasing the time for developing multi-target drugs. Then, this review aimed to compile to most relevant studies showing the anti-INFV effects of EGCG and its derivatives, which could become antiviral drug prototypes in the future.

Dichotomous Selectivity in Indium-Mediated Aza-Barbier-Type Allylation of 2-N-Acetyl Glycosyl Sulfinylimines in Brine: Convenient Access to Potent Anti-Influenza Agents

A highly diastereoselective indium-mediated allylation of 2-N-acetyl glycosyl sulfinylimines in brine under mild reaction conditions is reported. The method allows the achievement of a highly remarkable dichotomous selectivity for substrates, providing a single diastereoisomer of the product in 80-98% yield. With chiral (S)-homoallylic sulfinamide (R_S)-5 and (R_S)-8 formed as key intermediates, two potent anti-influenza agents, zanamivir and zanaphosphor, were synthesized in 50% and 41% overall yields, respectively.

Inhaled Medicines: Past, Present, and Future

The purpose of this review is to summarize essential pharmacological, pharmaceutical, and clinical aspects in the field of orally inhaled therapies that may help scientists seeking to develop new products. After general comments on the rationale for inhaled therapies for respiratory disease, the focus is on products approved approximately over the last half a century. The organization of these sections reflects the key pharmacological categories. Products for asthma and chronic obstructive pulmonary disease include β -2 receptor agonists, muscarinic acetylcholine receptor antagonists, glucocorticosteroids, and cromones as well as their combinations. The antiviral and antibacterial inhaled products to treat respiratory tract infections are then presented. Two "mucoactive" products-dornase α and mannitol, which are both approved for patients with cystic fibrosis-are reviewed. These are followed by sections on inhaled prostacyclins for pulmonary arterial hypertension and the challenging field of aerosol surfactant inhalation delivery, especially for prematurely born infants on ventilation support. The approved products for systemic delivery via the lungs for diseases of the central nervous system and insulin for diabetes are also discussed. New technologies for drug delivery by inhalation are analyzed, with the emphasis on those that would likely yield significant improvements over the technologies in current use or would expand the range of drugs and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of approved orally inhaled drug products for a variety of respiratory diseases and for systemic administration should be helpful in making judicious decisions about the development of new or improved inhaled drugs. These aspects include the choices of the active ingredients, formulations, delivery systems suitable for the target patient populations, and, to some extent, meaningful safety and efficacy endpoints in clinical trials.

Efficacy of the commercial plant products acting against influenza-a review

Background

Influenza infection always poses a threat to human and animal health. Vaccines and antiviral drugs are recommended to deal with the situation. The drawback of these remedial agents made the scientist change their focus on an alternative therapy. The anti-influenza effects of plants have been extensively studied, and many pharmaceutical companies have prepared their products on this basis.

Main body

The present review documents the successfully launched anti-influenza commercial products. In specific, it exposes the scientifically validated and evidence-based supporting inhibitory action of influenza and its strains.

Conclusion

This review highlighted the efficacy of the commercial products which effectively combat influenza. It provides a complementary strategy to deal with the worst-case scenario of flu. Meanwhile, to face the emerging strains, brand new products are in great necessity besides prevailing and available drugs.

Management of Severe Influenza

Influenza infection causes severe illness in 3 to 5 million people annually, with up to an estimated 650,000 deaths per annum. As such, it represents an ongoing burden to health care systems and human health. Severe acute respiratory infection can occur, resulting in respiratory failure requiring intensive care support. Herein we discuss diagnostic approaches, including development of CLIA-waived point of care tests that allow rapid diagnosis and treatment of influenza. Bacterial and fungal coinfections in severe influenza pneumonia are associated with worse outcomes, and we summarize the approach and treatment options for diagnosis and treatment of bacterial and Aspergillus coinfection. We discuss the available drug options for the treatment of severe influenza, and treatments which are no longer supported by the evidence base. Finally, we describe the supportive management and ventilatory approach to patients with respiratory failure as a result of severe influenza in the intensive care unit.

Bifunctional Inhibitors of Influenza Virus Neuraminidase: Molecular Design of a Sulfonamide Linker

The growing resistance of the influenza virus to widely used competitive neuraminidase inhibitors occupying the active site of the enzyme requires the development of bifunctional compounds that can simultaneously interact with other regulatory sites on the protein surface. When developing such an inhibitor and combining structural fragments that could be located in the sialic acid cavity of the active site and the adjacent 430-cavity, it is necessary to select a suitable linker not only for connecting the fragments, but also to ensure effective interactions with the unique arginine triad Arg118-Arg292-Arg371 of neuraminidase. Using molecular modeling, we have demonstrated the usefulness of the sulfonamide group in the linker design and the potential advantage of this functional group over other isosteric analogues.

Respiratory virus deterrence induced by modified mask filter

Airborne transmission of infectious respiratory pathogens is a significant health hazard for the general public as well as healthcare professionals. Face masks have been frequently utilized as safety measures to limit the transmission of these infectious aerosolized particles. However, the efficacy of face masks in reducing respiratory virus infectivity and pathogenicity is unknown. Improving the effectiveness of masks in blocking viruses is urgently needed. In this study, surgical mask filters were modified by coating the filters with 1, 3, or 5 M of sodium dihydrogen phosphate, and subsequently exposed to the aerosolized respiratory influenza viruses (A/H3N2, A/H5N1) generated by a nebulizer set. Mask filter modification significantly reduced the size and counts of filter pores, which enabled entrapment of 40-60% of aerosolized viruses (captured viruses) with more than 90% of the captured viruses losing their infectivity. Upon contact with the coated mask filters, both the captured viruses and the viruses that managed to bypass the filter pore (passed viruses) were found to be inactivated. Passed viruses demonstrated significantly reduced pathogenicity in mice as indicated by significantly reduced lung virus titers, bodyweight loss, and prolonged survival compared to bare control. These findings highlight the potential of modified mask filters for reducing viral activity and pathogenicity, which contributes to improving facial mask efficacy as well as limiting airborne pathogen transmission.

Discovery of a Novel Tetrapeptide against Influenza A Virus: Rational Design, Synthesis, Bioactivity Evaluation and Computational Studies

Influenza is a highly contagious, acute respiratory illness, which represents one of the main health issues worldwide. Even though some antivirals are available, the alarming increase in virus strains resistant to them highlights the need to find new drugs. Previously, Superti et al. deeply investigated the mechanism of the anti-influenza virus effect of bovine lactoferrin (bLf) and the role of its tryptic fragments (the N- and C-lobes) in antiviral activity. Recently, through a truncation library, we identified the tetrapeptides, Ac-SKHS-NH₂ (1) and Ac-SLDC-NH₂ (2), derived from bLf C-lobe fragment 418–429, which were able to bind hemagglutinin (HA) and inhibit cell infection in a concentration range of femto- to picomolar. Starting from these results, in this work, we initiated a systematic SAR study on the peptides mentioned above, through an alanine scanning approach. We carried out binding affinity measurements by microscale thermophoresis (MST) and surface plasmon resonance (SPR), as well as hemagglutination inhibition (HI) and virus neutralization (NT) assays on synthesized peptides. Computational studies were performed to identify possible ligand–HA interactions. Results obtained led to the identification of an interesting peptide endowed with broad anti-influenza activity and able to inhibit viral infection to a greater extent of reference peptide.

The Kinetic and Analytical Aspects of Enzyme Competitive Inhibition: Sensing of Tyrosinase Inhibitors

An amperometric biosensor based on tyrosinase, immobilized onto a carbon black paste electrode using glutaraldehyde and BSA was constructed to detect competitive inhibitors. Three inhibitors were used in this study: benzoic acid, sodium azide, and kojic acid, and the obtained values for fifty percent of inhibition (IC50) were 119 µM, 1480 µM, and 30 µM, respectively. The type of inhibition can also be determined from the curve of the degree of inhibition by considering the shift of the inhibition curves. Amperometric experiments were performed with a biosensor polarized at the potential -0.15 V vs. Ag/AgCl and using 0.1 M phosphate buffer (pH 6.8) as an electrolyte. Under optimized conditions, the proposed biosensor showed a linear amperometric response toward catechol detection from 0.5 µM to 38 µM with a detection limit of 0.35 µM (S/N = 3), and its sensitivity was 66.5 mA M-1 cm-2. Moreover, the biosensor exhibited a good storage stability. Conversely, a novel graphical plot for the determination of reversible competitive inhibition was represented for free tyrosinase. The graph consisted of plotting the half-time reaction (t1/2) as a function of the inhibitor concentration at various substrate concentrations. This innovative method relevance was demonstrated in the case of kojic acid using a colorimetric bioassay relying on tyrosinase inhibition. The results showed that the t1/2 provides an extended linear range of tyrosinase inhibitors.

Anti-high mobility group box 1 monoclonal antibody suppressed hyper-permeability and cytokine production in human pulmonary endothelial cells infected with influenza A virus

Objective

High mobility group box-1 (HMGB1) has been reported to be involved in influenza A virus-induced acute respiratory distress syndrome (ARDS). We studied the efficacy of an anti-HMGB1 mAb using an in vitro model of TNF-α stimulation or influenza A virus infection in human pulmonary microvascular endothelial cells (HMVECs).

Methods

Vascular permeability of HMVECs was quantified using the Boyden chamber assay under tumor necrosis factor-α (TNF-α) stimulation or influenza A virus infection in the presence of anti-HMGB1 mAb or control mAb. The intracellular localization of HMGB1 was assessed by immunostaining. Extracellular cytokine concentrations and intracellular viral mRNA expression were quantified by the enzyme-linked immunosorbent assay and quantitative reverse transcription PCR, respectively.

Results

Vascular permeability was increased by TNF-α stimulation or influenza A infection; HMVECs became elongated and the intercellular gaps were extended. Anti-HMGB1 mAb suppressed both the increase in permeability and the cell morphology changes. Translocation of HMGB1 to the cytoplasm was observed in the non-infected cells. Although anti-HMGB1 mAb did not suppress viral replication, it did suppress cytokine production in HMVECs.

Conclusion

Anti-HMGB1 mAb might be an effective therapy for severe influenza ARDS.

Inherent Serum Inhibition of Influenza Virus Neuraminidases

Influenza virus vaccines have been designed for human and veterinary medicine. The development for broadly protective influenza virus vaccines has propelled the vaccine field to investigate and include neuraminidase (NA) components into new vaccine formulations. The antibody-mediated protection induced by NA vaccines is quantified by inhibition of sialic acid cleavage. Non-immune inhibitors against influenza viruses naturally occur in varying proportions in sera from different species. In this brief report, the inherent ability of raw animal sera to inhibit a panel of influenza virus NA was determined. Raw sera from the same species inhibited more than 50% of influenza viruses tested from four different subtypes, but the breadth of inhibiting NA activity depended on the source of sera. Furthermore, different influenza viruses were inhibited by different sources of sera. Overall, additional studies are needed to ensure that scientific methods are consistent across studies in order to compare NA inhibition results. Through future investigation into the differences between sera from different animal species and how they influence NA inhibition assays, there can be effective development of a broadly protective influenza virus vaccines for veterinary and human use.

Non-human primate models of human respiratory infections

Respiratory pathogens represent a great burden for humanity and a potential source of new pandemics, as illustrated by the recent emergence of coronavirus disease 2019 (COVID-19). In recent decades, biotechnological advances have led to the development of numerous innovative therapeutic molecules and vaccine immunogens. However, we still lack effective treatments and vaccines against many respiratory pathogens. More than ever, there is a need for a fast, predictive, preclinical pipeline, to keep pace with emerging diseases. Animal models are key for the preclinical development of disease management strategies. The predictive value of these models depends on their ability to reproduce the features of the human disease, the mode of transmission of the infectious agent and the availability of technologies for monitoring infection. This review focuses on the use of non-human primates as relevant preclinical models for the development of prevention and treatment for human respiratory infections.

Defibrotide: potential for treating endothelial dysfunction related to viral and post-infectious syndromes

INTRODUCTION

Defibrotide (DF) is a polyribonucleotide with antithrombotic, pro-fibrinolytic, and anti-inflammatory effects on endothelium. These effects and the established safety of DF present DF as a strong candidate to treat viral and post-infectious syndromes involving endothelial dysfunction.

AREAS COVERED

We discuss DF and other therapeutic agents that have the potential to target endothelial components of pathogenesis in viral and post-infectious syndromes. We introduce defibrotide (DF), describe its mechanisms of action, and explore its established pleiotropic effects on the endothelium. We describe the established pathophysiology of Coronavirus Disease 2019 (COVID-19) and highlight the processes specific to COVID-19 potentially modulated by DF. We also present influenza A and viral hemorrhagic fevers, especially those caused by hantavirus, Ebola virus, and dengue virus, as viral syndromes in which DF might serve therapeutic benefit. Finally, we offer our opinion on novel treatment strategies targeting endothelial dysfunction in viral infections and their severe manifestations.

EXPERT OPINION

Given the critical role of endothelial dysfunction in numerous infectious syndromes, in particular COVID-19, therapeutic pharmacology for these conditions should increasingly prioritize endothelial stabilization. Several agents with endothelial protective properties should be further studied as treatments for severe viral infections and vasculitides, especially where other therapeutic modalities have failed.

Application of carbohydrates in approved small molecule drugs: A review

Carbohydrates are an important energy source and play numerous key roles in all living organisms. Carbohydrates chemistry involved in diagnosis and treatment of diseases has been attracting increasing attention. Carbohydrates could be one of the major focuses of new drug discovery. Currently, however, carbohydrate-containing drugs account for only a small percentage of all drugs in clinical use, which does not match the important roles of carbohydrates in the organism. In other words, carbohydrates are a relatively untapped source of new drugs and therefore may offer exciting novel therapeutic opportunities. Here, we presented an overview of the application of carbohydrates in approved small molecule drugs and emphasized and evaluated the roles of carbohydrates in those drugs. The potential development direction of carbohydrate-containing drugs was presented after summarizing the advantages and challenges of carbohydrates in the development of new drugs.

Substantial effect of phytochemical constituents against the pandemic disease influenza-a review

Background

Influenza is an acute respiratory tract infection caused by the influenza virus. Vaccination and antiviral drugs are the two methods opted to control the disease. Besides their efficiency, they also cause adverse side effects. Hence, scientists turned their attention to powerful herbal medicines. This review put focus on various proven, scientifically validated anti-influenza compounds produced by the plants suggested for the production of newer drugs for the better treatment of influenza and its related antiviral diseases too.

Main body

In this review, fifty medicinal herb phytochemical constituents and their anti-influenza activities have been documented. Specifically, this review brings out the accurate and substantiates mechanisms of action of these constituents. This study categorizes the phytochemical constituents into primary and secondary metabolites which provide a source for synthesizing and developing new drugs.

Conclusion

This article provides a summary of the actions of the herbal constituents. Since the mechanisms of action of the components are elucidated, the pandemic situation arising due to influenza and similar antiviral diseases can be handled promisingly with greater efficiency. However, clinical trials are in great demand. The formulation of usage may be a single drug compound or multi-herbal combination. These, in turn, open up a new arena for the pharmaceutical industries to develop innovative drugs.