The broad anti-viral agent glycyrrhizin directly modulates the fluidity of plasma membrane and HIV-1 envelope

Anti-HIV activity in traditional Chinese medicine: clinical implications of monomeric herbal remedies and compound decoctions

With the global spread of human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS), the pursuit of potent treatments has ascended as a paramount concern in global healthcare. Traditional Chinese medicine (TCM) has been used for thousands of years in China and other East Asian countries and it offers remedies for an extensive array of ailments, including HIV and AIDS. This review focuses on the clinical significance of single herbs and composite tonics in TCM with antiviral activity against HIV. Initially, the anti-HIV activity of single herbs was analyzed in detail. Many herbs have been shown to have significant anti-HIV activity. The active ingredients of these herbs exhibit their anti-HIV effects through various mechanisms, such as inhibiting viral replication, preventing viral binding to host cells, and interfering with the viral lifecycle. Furthermore, we delved into the clinical significance of HIV-associated formulations provided as a result of Chinese compound prescription. These combinations of herbal ingredients are designed to amplify therapeutic efficacy and minimize adverse effects. Clinical trials have demonstrated the therapeutic benefits of these prescriptions for individuals infected with HIV. The intricate composition of these prescriptions potentially augments their anti-HIV activity through synergistic effects. Additionally, this review underscores the clinical importance of TCM in the context of HIV treatment. While numerous herbs and prescriptions exhibit anti-HIV activity, their safety and efficacy in clinical applications warrant further investigation. When combined with contemporary antiretroviral drugs, TCM may serve as an adjunctive therapy, assisting in reducing side effects, and enhancing patients' quality of life. To optimally harness these natural resources, further exploration is imperative to ascertain their efficacy, safety, and optimal utilization, thereby offering a broader spectrum of therapeutic options for HIV-afflicted individuals.

The mutual lipid-mediated effect of the transmembrane domain of SARS-CoV-2 E-protein and glycyrrhizin nicotinate derivatives on the localization in the lipid bilayer

Glycyrrhizinic acid (GA) is one of the active substances in licorice root. It exhibits antiviral activity against various enveloped viruses, for example, SARS-CoV-2. GA derivatives are promising biologically active compounds from perspective of developing broad-spectrum antiviral agents. Given that GA nicotinate derivatives (Glycyvir) demonstrate activity against various DNA- and RNA-viruses, a search for a possible mechanism of action of these compounds is required. In the present paper, the interaction of Glycyvir with the transmembrane domain of the SARS-CoV-2 E-protein (ETM) in a model lipid membrane was investigated by NMR spectroscopy and molecular dynamics simulation. The lipid-mediated influence on localization of the SARS-CoV-2 E-protein by Glycyvir was observed. The presence of Glycyvir leads to deeper immersion of the ETM in lipid bilayer. Taking into account that E-protein plays a significant role in virus production and takes part in virion assembly and budding, the data on the effect of potential antiviral agents on ETM localization and structure in the lipid environment may provide a basis for further studies of potential coronavirus E-protein inhibitors.

Deciphering the distinct biocontrol activities of lipopeptides fengycin and surfactin through their differential impact on lipid membranes

Lipopeptides produced by beneficial bacilli present promising alternatives to chemical pesticides for plant biocontrol purposes. Our research explores the distinct plant biocontrol activities of lipopeptides surfactin (SRF) and fengycin (FGC) by examining their interactions with lipid membranes. Our study shows that FGC exhibits a direct antagonistic activity against Botrytis cinerea and no marked immune-eliciting activity in Arabidopsis thaliana while SRF only demonstrates an ability to stimulate plant immunity. It also reveals that SRF and FGC exhibit diverse effects on membrane integrity and lipid packing. SRF primarily influences membrane physical state without significant membrane permeabilization, while FGC permeabilizes membranes without significantly affecting lipid packing. From our results, we can suggest that the direct antagonistic activity of lipopeptides is linked to their capacity to permeabilize lipid membrane while the stimulation of plant immunity is more likely the result of their ability to alter the mechanical properties of the membrane. Our work also explores how membrane lipid composition modulates the activities of SRF and FGC. Sterols negatively impact both lipopeptides' activities while sphingolipids mitigate the effects on membrane lipid packing but enhance membrane leakage. In conclusion, our findings emphasize the importance of considering both membrane lipid packing and leakage mechanisms in predicting the biological effects of lipopeptides. It also sheds light on the intricate interplay between the membrane composition and the effectiveness of the lipopeptides, providing insights for targeted biocontrol agent design.

Glycyrrhizinic Acid as an Antiviral and Anticancer Agent in the Treatment of Human Papillomavirus

Human papillomavirus (HPV), like any other virus, needs to penetrate the host cell and make use of its machinery to replicate. From there, HPV infection can be asymptomatic or lead to benign and premalignant lesions or even different types of cancer. HPV oncogenesis is due to the ability of the viral oncoproteins E6 and E7 to alter the control mechanisms for the growth and proliferation of host cell. Therefore, the use of agents with the ability to control these processes is essential in the search for effective treatments against HPV infections. Glycyrrhizinic acid (Gly), the active ingredient in liquorice, has been shown in numerous preclinical studies to have an antiviral and anticancer activity, reducing the expression of E6 and E7 and inducing apoptosis in cervical cancer cells. In addition, it also has antioxidant, anti-inflammatory, immunomodulatory or re-epithelializing properties that can be useful in HPV infections. This review includes the different antiviral and anticancer mechanisms described for Gly, as well as the clinical studies carried out that position it as a potential therapeutic strategy against HPV both through its topical application and by oral administration.

The Interaction of the Transmembrane Domain of SARS-CoV-2 E-Protein with Glycyrrhizic Acid in Lipid Bilayer

The interaction of the transmembrane domain of SARS-CoV-2 E-protein with glycyrrhizic acid in a model lipid bilayer (small isotropic bicelles) is demonstrated using various NMR techniques. Glycyrrhizic acid (GA) is the main active component of licorice root, and it shows antiviral activity against various enveloped viruses, including coronavirus. It is suggested that GA can influence the stage of fusion between the viral particle and the host cell by incorporating into the membrane. Using NMR spectroscopy, it was shown that the GA molecule penetrates into the lipid bilayer in a protonated state, but localizes on the bilayer surface in a deprotonated state. The transmembrane domain of SARS-CoV-2 E-protein facilitates deeper GA penetration into the hydrophobic region of bicelles at both acidic and neutral pH and promotes the self-association of GA at neutral pH. Phenylalanine residues of the E-protein interact with GA molecules inside the lipid bilayer at neutral pH. Furthermore, GA influences the mobility of the transmembrane domain of SARS-CoV-2 E-protein in the bilayer. These data provide deeper insight into the molecular mechanism of antiviral activity of glycyrrhizic acid.

A Review of the Antiviral Activities of Glycyrrhizic Acid, Glycyrrhetinic Acid and Glycyrrhetinic Acid Monoglucuronide

Licorice, a natural medicine derived from the roots and rhizomes of Glycyrrhiza species, possesses a wide range of therapeutic applications, including antiviral properties. Glycyrrhizic acid (GL) and glycyrrhetinic acid (GA) are the most important active ingredients in licorice. Glycyrrhetinic acid 3-O-mono-β-d-glucuronide (GAMG) is the active metabolite of GL. GL and its metabolites have a wide range of antiviral activities against viruses, such as, the hepatitis virus, herpes virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and so on. Although their antiviral activity has been widely reported, the specific mechanism of action involving multiple links such as the virus itself, cells, and immunity are not clearly established. In this review, we will give an update on the role of GL and its metabolites as antiviral agents, and detail relevant evidence on the potential use and mechanisms of actions. Analyzing antivirals, their signaling, and the impacts of tissue and autoimmune protection may provide promising new therapeutic strategies.

Production of 11-Oxo-β-Amyrin in Saccharomyces cerevisiae at High Efficiency by Fine-Tuning the Expression Ratio of CYP450:CPR

The production of glycyrrhetinic acid (GA) and 11-oxo-β-amyrin, the major bioactive components in liquorice, was typically inhibited by P450 oxidation in Saccharomyces cerevisiae. This study focused on optimizing CYP88D6 oxidation by balancing its expression with cytochrome P450 oxidoreductase (CPR) for the efficient production of 11-oxo-β-amyrin in yeast. Results indicated that a high CPR:CYP88D6 expression ratio could decrease both 11-oxo-β-amyrin concentration and turnover ratio of β-amyrin to 11-oxo-β-amyrin, whereas a high CYP88D6:CPR expression ratio is beneficial for improving the catalytic activity of CYP88D6 and 11-oxo-β-amyrin production. Under such a scenario, 91.2% of β-amyrin was converted into 11-oxo-β-amyrin in the resulting S. cerevisiae Y321, and 11-oxo-β-amyrin production was further improved to 810.6 mg/L in fed-batch fermentation. Our study provides new insights into the expression of cytochrome P450 and CPR in maximizing the catalytic activity of P450s, which could guide the construction of cell factories in producing natural products.

Broad Antiviral Spectrum of Glycyrrhizic Acid for Human and Veterinary Medicine: Reality or Fiction?

BACKGROUND

Emerging virus infections provoke health problems in people and animals, which generate social and economic issues worldwide. This has spurred the search for new pharmacological strategies to confront them.

SUMMARY

The purpose of this review is to draw the reader's attention to pharmacological evaluations of glycyrrhizic acid (GA) and its analogs on the broad range of viruses known in human and veterinary medicine. GA is the main water-soluble constituent extracted from the roots of plants from the genus Glycyrrhiza, commonly known as licorice root. It has long been used due to its broad spectrum of bioactivities, including anti-inflammatory, antiulcer, and antitumor properties. It has also been proposed as an antiviral agent. Medicines derived from GA are currently being used to combat acute and chronic hepatitis and herpes viruses.

KEY MESSAGES

This review suggests that GA could be a new broad-spectrum antiviral due to its ability to inhibit DNA or RNA viruses both in vitro and in vivo. GA could be a potential drug for preventing and/or treating various viral diseases.

Recent Advances in Antiviral Activities of Triterpenoids

Triterpenoids, important secondary plant metabolites made up of six isoprene units, are found widely in higher plants and are studied for their structural variety and wide range of bioactivities, including antiviral, antioxidant, anticancer, and anti-inflammatory properties. Numerous studies have demonstrated that different triterpenoids have the potential to behave as potential antiviral agents. The antiviral activities of triterpenoids and their derivatives are summarized in this review, with examples of oleanane, ursane, lupane, dammarane, lanostane, and cycloartane triterpenoids. We concentrated on the tetracyclic and pentacyclic triterpenoids in particular. Furthermore, the particular viral types and possible methods, such as anti-human immunodeficiency virus (HIV), anti-influenza virus, and anti-hepatitis virus, are presented in this article. This review gives an overview and a discussion of triterpenoids as potential antiviral agents.

New Aspects of the Antioxidant Activity of Glycyrrhizin Revealed by the CIDNP Technique

Electron transfer plays a crucial role in ROS generation in living systems. Molecular oxygen acts as the terminal electron acceptor in the respiratory chains of aerobic organisms. Two main mechanisms of antioxidant defense by exogenous antioxidants are usually considered. The first is the inhibition of ROS generation, and the second is the trapping of free radicals. In the present study, we have elucidated both these mechanisms of antioxidant activity of glycyrrhizin (GL), the main active component of licorice root, using the chemically induced dynamic nuclear polarization (CIDNP) technique. First, it was shown that GL is capable of capturing a solvated electron, thereby preventing its capture by molecular oxygen. Second, we studied the effect of glycyrrhizin on the behavior of free radicals generated by UV irradiation of xenobiotic, NSAID—naproxen in solution. The structure of the glycyrrhizin paramagnetic intermediates formed after the capture of a solvated electron was established from a photo-CIDNP study of the model system—the dianion of 5-sulfosalicylic acid and DFT calculations.

Recent advances in glycyrrhizin metabolism, health benefits, clinical effects and drug delivery systems for efficacy improvement; a comprehensive review

BACKGROUND

Glycyrrhizin (GL) is a major active constituent of licorice root (Glycyrrhiza glabra) that is considered one of the oldest and most frequently employed botanicals in Chinese medicine and worldwide, with most effects attributed to its rich GL content. Structurally, GL a triterpene saponin that is widely used as a flavoring agent in foodstuffs and cosmetics, and also proposed for various clinical applications with a myriad of health benefits. Pharmacological and biological activities of GL include antiviral, anti-inflammatory, antioxidant, and anticancer activities (in vitro and in vivo). Currently, there is no comprehensive review on GL biological effects and its action mechanisms.

PURPOSE

This review summarizes GL pharmacological actions from a molecular biology perception, presented on its metabolism and side effects based on in vitro, in vitro and clinical studies. Moreover, the potential of GL as a nanomedicine delivery system is also summarized. The progress in drug delivery research using GL presented herein is expected to provide a theoretical basis for developing other novel drugs formulations.

METHODS

A systematic review was carried out in several electronic databases (Science Direct, SpringerLink, CNKI, PubMed, Web of Science, Elsevier, and Scopus), using the following key words: glycyrrhizin "AND" bioactivity "OR" clinic "OR" therapeutic "OR" drug delivery. This search included manuscripts published between 1989 and 2021.

RESULTS

126 researches were selected and summarized in this review. The analysis of these studies indicated that GL has antiviral activity against different viruses. Further, GL efficiently suppressed the respiratory manifestations associated with COVID-19 by reducing the expression of angiotensin converting enzyme 2 (ACE2) that employed by the virus as an entry point. Otherwise, GL was found to induce antioxidant, anti-inflammatory, immune-modulatory, and anticancer activity. Besides, diminution the particle size of GL to nanometer size significantly augments their action and biodistribution.

CONCLUSION

This article summarizes the pharmacological actions of GL. The potential of GL as a nanomedicine delivery system is also presented. Nevertheless, most studies reported provide no deep insight of GL health effects warranting for more future studies to elucidate its action mechanism and potential therapeutic benefits through preclinical and clinical trials.

Isoquercetin as an Anti-Covid-19 Medication: A Potential to Realize

Isoquercetin and quercetin are secondary metabolites found in a variety of plants, including edible ones. Isoquercetin is a monoglycosylated derivative of quercetin. When ingested, isoquercetin accumulates more than quercetin in the intestinal mucosa where it is converted to quercetin; the latter is absorbed into enterocytes, transported to the liver, released in circulation, and distributed to tissues, mostly as metabolic conjugates. Physiologically, isoquercetin and quercetin exhibit antioxidant, anti-inflammatory, immuno-modulatory, and anticoagulant activities. Generally isoquercetin is less active than quercetin in vitro and ex vivo, whereas it is equally or more active in vivo, suggesting that it is primarily a more absorbable precursor to quercetin, providing more favorable pharmacokinetics to the latter. Isoquercetin, like quercetin, has shown broad-spectrum antiviral activities, significantly reducing cell infection by influenza, Zika, Ebola, dengue viruses among others. This ability, together with their other physiological properties and their safety profile, has led to the proposition that administration of these flavonols could prevent infection by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), or arrest the progression to severity and lethality of resulting coronavirus disease of 2019 (Covid-19). In silico screening of small molecules for binding affinity to proteins involved SARS-CoV-2 life cycle has repeatedly situated quercetin and isoquercetin near to top of the list of likely effectors. If experiments in cells and animals confirm these predictions, this will provide additional justifications for the conduct of clinical trials to evaluate the prophylactic and therapeutic efficacy of these flavonols in Covid-19.

Role of Protein-Lipid Interactions in Viral Entry

The viral entry consists of several sequential events that ensure the attachment of the virus to the host cell and the introduction of its genetic material for the continuation of the replication cycle. Both cellular and viral lipids have gained a wider focus in recent years in the field of viral entry, as they are found to play key roles in different steps of the process. The specific role is summarized that lipids and lipid membrane nanostructures play in viral attachment, fusion, and immune evasion and how they can be targeted with antiviral therapies. Finally, some of the limitations of techniques commonly used for protein-lipid interactions studies are discussed, and new emerging tools are reviewed that can be applied to this field.

Photostabilization of ketoprofen by inclusion in glycyrrhizin micelles and gel nanoparticles

Ketoprofen (KP) is known to be the most photosensitive among the nonsteroidal anti-inflammatory drugs and may induce phototoxic and photoallergic reactions. Phototoxic side effects of KP are associated with the...

Licorice (Glycyrrhiza glabra) Extracts-Suitable Pharmacological Interventions for COVID-19? A Review

Even though vaccination has started against COVID-19, people should continue maintaining personal and social caution as it takes months or years to get everyone vaccinated, and we are not sure how long the vaccine remains efficacious. In order to contribute to the mitigation of COVID-19 symptoms, the pharmaceutical industry aims to develop antiviral drugs to inhibit the SARS-CoV-2 replication and produce anti-inflammatory medications that will inhibit the acute respiratory distress syndrome (ARDS), which is the primary cause of mortality among the COVID-19 patients. In reference to these tasks, this article considers the properties of a medicinal plant named licorice (Glycyrrhiza glabra), whose phytochemicals have shown both antiviral and anti-inflammatory tendencies through previous studies. All the literature was selected through extensive search in various databases such as google scholar, Scopus, the Web of Science, and PubMed. In addition to the antiviral and anti-inflammatory properties, one of the licorice components has an autophagy-enhancing mechanism that studies have suggested to be necessary for COVID-19 treatment. Based on reviewing relevant professional and historical literature regarding the medicinal properties of licorice, it is suggested that it may be worthwhile to conduct in vitro and in vivo studies, including clinical trials with glycyrrhizic and glycyrrhetinic acids together with other flavonoids found in licorice, as there is the potentiality to provide natural interventions against COVID-19 symptoms.

Lipids in Pathophysiology and Development of the Membrane Lipid Therapy: New Bioactive Lipids

Membranes are mainly composed of a lipid bilayer and proteins, constituting a checkpoint for the entry and passage of signals and other molecules. Their composition can be modulated by diet, pathophysiological processes, and nutritional/pharmaceutical interventions. In addition to their use as an energy source, lipids have important structural and functional roles, e.g., fatty acyl moieties in phospholipids have distinct impacts on human health depending on their saturation, carbon length, and isometry. These and other membrane lipids have quite specific effects on the lipid bilayer structure, which regulates the interaction with signaling proteins. Alterations to lipids have been associated with important diseases, and, consequently, normalization of these alterations or regulatory interventions that control membrane lipid composition have therapeutic potential. This approach, termed membrane lipid therapy or membrane lipid replacement, has emerged as a novel technology platform for nutraceutical interventions and drug discovery. Several clinical trials and therapeutic products have validated this technology based on the understanding of membrane structure and function. The present review analyzes the molecular basis of this innovative approach, describing how membrane lipid composition and structure affects protein-lipid interactions, cell signaling, disease, and therapy (e.g., fatigue and cardiovascular, neurodegenerative, tumor, infectious diseases).

Glycyrrhizic Acid Inhibits SARS-CoV-2 Infection by Blocking Spike Protein-Mediated Cell Attachment

Glycyrrhizic acid (GA), also known as glycyrrhizin, is a triterpene glycoside isolated from plants of Glycyrrhiza species (licorice). GA possesses a wide range of pharmacological and antiviral activities against enveloped viruses including severe acute respiratory syndrome (SARS) virus. Since the S protein (S) mediates SARS coronavirus 2 (SARS-CoV-2) cell attachment and cell entry, we assayed the GA effect on SARS-CoV-2 infection using an S protein-pseudotyped lentivirus (Lenti-S). GA treatment dose-dependently blocked Lenti-S infection. We showed that incubation of Lenti-S virus, but not the host cells with GA prior to the infection, reduced Lenti-S infection, indicating that GA targeted the virus for infection. Surface plasmon resonance measurement showed that GA interacted with a recombinant S protein and blocked S protein binding to host cells. Autodocking analysis revealed that the S protein has several GA-binding pockets including one at the interaction interface to the receptor angiotensin-converting enzyme 2 (ACE2) and another at the inner side of the receptor-binding domain (RBD) which might impact the close-to-open conformation change of the S protein required for ACE2 interaction. In addition to identifying GA antiviral activity against SARS-CoV-2, the study linked GA antiviral activity to its effect on virus cell binding.

Research Progress on the Antiviral Activity of Glycyrrhizin and its Derivatives in Liquorice

Liquorice is a traditional medicine. Triterpenoids such as glycyrrhizin and glycyrrhetinic acid are the main active constituents of liquorice. Studies have revealed that these compounds exert inhibitory effects on several viruses, including SARS-CoV-2. The main mechanisms of action of these compounds include inhibition of virus replication, direct inactivation of viruses, inhibition of inflammation mediated by HMGB1/TLR4, inhibition of β-chemokines, reduction in the binding of HMGB1 to DNA to weaken the activity of viruses, and inhibition of reactive oxygen species formation. We herein review the research progress on the antiviral effects of glycyrrhizin and its derivatives. In addition, we emphasise the significance of exploring unknown antiviral mechanisms, structural modifications, and drug combinations in future studies.

Can Antiviral Activity of Licorice Help Fight COVID-19 Infection?

The phytotherapeutic properties of Glycyrrhiza glabra (licorice) extract are mainly attributed to glycyrrhizin (GR) and glycyrrhetinic acid (GA). Among their possible pharmacological actions, the ability to act against viruses belonging to different families, including SARS coronavirus, is particularly important. With the COVID-19 emergency and the urgent need for compounds to counteract the pandemic, the antiviral properties of GR and GA, as pure substances or as components of licorice extract, attracted attention in the last year and supported the launch of two clinical trials. In silico docking studies reported that GR and GA may directly interact with the key players in viral internalization and replication such as angiotensin-converting enzyme 2 (ACE2), spike protein, the host transmembrane serine protease 2, and 3-chymotrypsin-like cysteine protease. In vitro data indicated that GR can interfere with virus entry by directly interacting with ACE2 and spike, with a nonspecific effect on cell and viral membranes. Additional anti-inflammatory and antioxidant effects of GR cannot be excluded. These multiple activities of GR and licorice extract are critically re-assessed in this review, and their possible role against the spread of the SARS-CoV-2 and the features of COVID-19 disease is discussed.

In Vitro Synergistic Inhibition of HT-29 Proliferation and 2H-11 and HUVEC Tubulogenesis by Bacopaside I and II Is Associated with Ca2+ Flux and Loss of Plasma Membrane Integrity

We previously showed how triterpene saponin bacopaside (bac) II, purified from the medicinal herb Bacopa monnieri, induced cell death in colorectal cancer cell lines and reduced endothelial cell migration and tube formation, and further demonstrated a synergistic effect of a combination of bac I and bac II on the inhibition of breast cancer cell line growth. Here, we assessed the effects of bac I and II on the colorectal cancer HT-29 cell line, and mouse (2H-11) and human umbilical vein endothelial cell (HUVEC) lines, measuring outcomes including cell viability, proliferation, migration, tube formation, apoptosis, cytosolic Ca²⁺ levels and plasma membrane integrity. Combined bac I and II, each applied at concentrations below IC₅₀ values, caused a synergistic reduction of the viability and proliferation of HT-29 and endothelial cells, and impaired the migration of HT-29 and tube formation of endothelial cells. A significant enhancement of apoptosis was induced only in HUVEC, although an increase in cytosolic Ca²⁺ was detected in all three cell lines. Plasma membrane integrity was compromised in 2H-11 and HUVEC, as determined by an increase in propidium iodide staining, which was preceded by Ca²⁺ flux. These in vitro findings support further research into the mechanisms of action of the combined compounds for potential clinical use.

pH-Sensitive Glycyrrhizin Based Vesicles for Nifedipine Delivery

Glycyrrhizic acid, or glycyrrhizin (GA), a major active component of licorice root, has been widely used in traditional Chinese and Japanese medicine since ancient times. However, only in the last decades has a novel and unusual property of the GA been discovered to form water-soluble, supramolecular complexes with a variety of lipophilic drugs. These complexes show significant advantages over other known delivery systems, in particular, due to strong pH sensitivity, the properties of GA self-associates. In the present study, a supramolecular complex formation of the hypotensive and antiarrhythmic drug nifedipine with GA has been studied at different pH values, corresponding to the different degrees of GA dissociation, including a fully dissociated state of GA. Both NMR experiments and molecular dynamics simulations demonstrate the existence of the nifedipine complex with GA at all dissociation states of GA. However, optical absorption experiments show the decrease of complex stability and solubility at pH > 6 when the GA molecule is fully deprotonated. It means the higher release rate of the drug in a neutral and basic environment compared with acid media. These results could form the basis of follow-up studies of GA self-associates as pH-controlled drug delivery systems.

Nanotechnology for virus treatment

The continued emergence of novel viruses poses a significant threat to global health. Uncontrolled outbreaks can result in pandemics that have the potential to overburden our healthcare and economic systems. While vaccination is a conventional modality that can be employed to promote herd immunity, antiviral vaccines can only be applied prophylactically and do little to help patients who have already contracted viral infections. During the early stages of a disease outbreak when vaccines are unavailable, therapeutic antiviral drugs can be used as a stopgap solution. However, these treatments do not always work against emerging viral strains and can be accompanied by adverse effects that sometimes outweigh the benefits. Nanotechnology has the potential to overcome many of the challenges facing current antiviral therapies. For example, nanodelivery vehicles can be employed to drastically improve the pharmacokinetic profile of antiviral drugs while reducing their systemic toxicity. Other unique nanomaterials can be leveraged for their virucidal or virus-neutralizing properties. In this review, we discuss recent developments in antiviral nanotherapeutics and provide a perspective on the application of nanotechnology to the SARS-CoV-2 outbreak and future virus pandemics.

Advances in Pharmacological Activities and Mechanisms of Glycyrrhizic Acid

Licorice (Glycyrrhiza glabra L.) is widely regarded as an important medicinal plant and has been used for centuries in traditional medicine because of its therapeutic properties. Studies have shown that metabolites isolated from licorice have many pharmacological activities, such as antiinflammatory, anti-viral, participation in immune regulation, anti-tumor and other activities. This article gives an overview of the pharmacological activities and mechanisms of licorice metabolites and the adverse reactions that need attention. This review helps to further investigate the possibility of licorice as a potential drug for various diseases. It is hoped that this review can provide a relevant theoretical basis for relevant scholars' research and their own learning.

Deciphering the Pharmacological Mechanisms of Ma Xing Shi Gan Decoction against COVID-19 through Integrating Network Pharmacology and Experimental Exploration

The outbreak of new infectious pneumonia caused by SARS-CoV-2 has posed a significant threat to public health, but specific medicines and vaccines are still being developed. Traditional Chinese medicine (TCM) has thousands of years of experience in facing the epidemic disease, such as influenza and viral pneumonia. In this study, we revealed the efficacy and pharmacological mechanism of Ma Xing Shi Gan (MXSG) Decoction against COVID-19. First, we used liquid chromatography–electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) to analyze the chemical components in MXSG and identified a total of 97 components from MXSG. Then, the intervention pathway of MXSG based on these components was analyzed with network pharmacology, and it was found that the pathways related to the virus infection process were enriched in some of MXSG component targets. Simultaneously, through literature research, it was preliminarily determined that MXSG, which is an essential prescription for treating COVID-19, shared the feature of antiviral, improving clinical symptoms, regulating immune inflammation, and inhibiting lung injury. The regulatory mechanisms associated with its treatment of COVID-19 were proposed. That MXSG might directly inhibit the adsorption and replication of SARS-CoV-2 at the viral entry step. Besides, MXSG might play a critical role in inflammation and immune regulatory, that is, to prevent cytokine storm and relieve lung injury through toll-like receptors signaling pathway. Next, in this study, the regulatory effect of MXSG on inflammatory lung injury was validated through transcriptome results. In summary, MXSG is a relatively active and safe treatment for influenza and viral pneumonia, and its therapeutic effect may be attributed to its antiviral and anti-inflammatory effects.

Traditional Chinese Medicine as Potential Therapy for COVID-19

In December 2019, a novel coronavirus SARS-CoV-2, causing the disease COVID-19, spread from Wuhan throughout China and has infected people over 200 countries. Thus far, more than 3,400,000 cases and 240,000 deaths have occurred worldwide, and the coronavirus pandemic continues to grip the globe. While numbers of cases in China have been steadying, the number of infections outside China is increasing at a worrying pace. We face an urgent need to control the spread of the COVID-19 epidemic, which is currently expanding to a global pandemic. Efforts have focused on testing antiviral drugs and vaccines, but there is currently no treatment specifically approved. Traditional Chinese medicine (TCM) is grounded in empirical observations and the Chinese people use TCM to overcome these sorts of plagues many times in thousands of years of history. Currently, the Chinese National Health Commission recommended a TCM prescription of Qing-Fei-Pai-Du-Tang (QFPDT) in the latest version of the "Diagnosis and Treatment guidelines of COVID-19" which has been reported to provide reliable effects for COVID-19. While doubts about TCM still exist today, this review paper will describe the rationalities that QFPDT is likely to bring a safe and effective treatment of COVID-19.

Various Facets of Pathogenic Lipids in Infectious Diseases: Exploring Virulent Lipid-Host Interactome and Their Druggability

Lipids form an integral, structural, and functional part of all life forms. They play a significant role in various cellular processes such as membrane fusion, fission, endocytosis, protein trafficking, and protein functions. Interestingly, recent studies have revealed their more impactful and critical involvement in infectious diseases, starting with the manipulation of the host membrane to facilitate pathogenic entry. Thereafter, pathogens recruit specific host lipids for the maintenance of favorable intracellular niche to augment their survival and proliferation. In this review, we showcase the lipid-mediated host pathogen interplay in context of life-threatening viral and bacterial diseases including the recent SARS-CoV-2 infection. We evaluate the emergent lipid-centric approaches adopted by these pathogens, while delineating the alterations in the composition and organization of the cell membrane within the host, as well as the pathogen. Lastly, crucial nexus points in their interaction landscape for therapeutic interventions are identified. Lipids act as critical determinants of bacterial and viral pathogenesis by altering the host cell membrane structure and functions.

Effect of Glycyrrhizic Acid and Arabinogalactan on the Membrane Potential of Rat Thymocytes Studied by Potential-Sensitive Fluorescent Probe

The effect of the natural saponin glycyrrhizic acid (GA) and polysaccharide arabinogalactan (AG) on the transmembrane potential of rat thymocytes was investigated using the potential-sensitive fluorescent probe 4-(p-dimethylaminostyryl)-1-methylpyridinium (DSM). Incubation of cells with GA in micellar form resulted in a decrease of the amplitude of observed fluorescence kinetics that points out to a decrease of the transmembrane potential. The proposed mechanism is an increase of membrane ion permeability (passive ion transport) of the plasma cell membrane due to GA incorporation. The incorporation of GA molecules into the cell membrane is extremely sensitive to the degree of GA dissociation. The neutral form of glycyrrhizic acid enters the lipid bilayer in contrast to the deprotonated anionic form. The incubation of rat thymocytes with anionic form of GA, namely with its disodium salt, has no effect on the fluorescence kinetics. The possible reasons of this phenomenon are discussed in the light of the nuclear magnetic resonance (NMR) and molecular dynamics (MD) data. The treatment of thymocytes with AG affects only the initial rate of the probe incorporation. The proposed mechanism is that AG covers the surface of the cell membrane and forms a barrier for the probe. Additionally, our experiments demonstrated that both polysaccharide AG and GA in the neutral form (but not Na₂GA) effectively capture the cationic probe in an aqueous solution and then deliver it to the cell membrane.

Glycyrrhizin: An alternative drug for the treatment of COVID-19 infection and the associated respiratory syndrome?

Safe and efficient drugs to combat the current COVID-19 pandemic are urgently needed. In this context, we have analyzed the anti-coronavirus potential of the natural product glycyrrhizic acid (GLR), a drug used to treat liver diseases (including viral hepatitis) and specific cutaneous inflammation (such as atopic dermatitis) in some countries. The properties of GLR and its primary active metabolite glycyrrhetinic acid are presented and discussed. GLR has shown activities against different viruses, including SARS-associated Human and animal coronaviruses. GLR is a non-hemolytic saponin and a potent immuno-active anti-inflammatory agent which displays both cytoplasmic and membrane effects. At the membrane level, GLR induces cholesterol-dependent disorganization of lipid rafts which are important for the entry of coronavirus into cells. At the intracellular and circulating levels, GLR can trap the high mobility group box 1 protein and thus blocks the alarmin functions of HMGB1. We used molecular docking to characterize further and discuss both the cholesterol- and HMG box-binding functions of GLR. The membrane and cytoplasmic effects of GLR, coupled with its long-established medical use as a relatively safe drug, make GLR a good candidate to be tested against the SARS-CoV-2 coronavirus, alone and in combination with other drugs. The rational supporting combinations with (hydroxy)chloroquine and tenofovir (two drugs active against SARS-CoV-2) is also discussed. Based on this analysis, we conclude that GLR should be further considered and rapidly evaluated for the treatment of patients with COVID-19.

Advances in Pharmacological Activities of Terpenoids

Terpenoids, the most abundant compounds in natural products, are a set of important secondary metabolites in plants with diverse structures. Terpenoids play key roles in plant growth and development, response to the environment, and physiological processes. As raw materials, terpenoids were also widely used in pharmaceuticals, food, and cosmetics industries. Terpenoids possess antitumor, anti-inflammatory, antibacterial, antiviral, antimalarial effects, promote transdermal absorption, prevent and treat cardiovascular diseases, and have hypoglycemic activities. In addition, previous studies have also found that terpenoids have many potential applications, such as insect resistance, immunoregulation, antioxidation, antiaging, and neuroprotection. Terpenoids have a complex structure with diverse effects and different mechanisms of action. Activities and mechanisms of terpenoids were reviewed in this paper. The development and application prospect of terpenoid compounds were also prospected, which provides a useful reference for new drug discovery and drug design based on terpenoids.

Research Progress of Glycyrrhizic Acid on Antiviral Activity

Glycyrrhizic acid (GA), a triterpene isolated from the roots and rhizomes of licorice, named Glycyrrhiza glabra, is the principal bioactive ingredient of anti-viral, anti-inflammatory and hepatoprotective effects. GA has been used in the clinical treatment of hepatitis, bronchitis, gastric ulcer, AIDS (acquired immunodeficiency syndrome), certain cancers and skin diseases. It has a direct effect on anti-HBV (hepatitis B virus) via affecting the HBsAg (hepatitis B surface antigen) to extracellular secretion, improving liver dysfunction in patients with chronic hepatitis B, and ultimately improving the immune status of HBV. GA can significantly inhibit the proliferation of HIV, showing an immune activation. The clinical application of GA on the prevention and treatments of various diseases may derive from its numerous pharmacological properties. This review provides the summary of the antiviral effects of GA on research progress and mechanism in recent years.

HIV-1 protease and reverse transcriptase inhibition by tiger milk mushroom (Lignosus rhinocerus) sclerotium extracts: In vitro and in silico studies

Background and aim

Lignosus rhinocerus (LR) is an edible mushroom with a variety of medicinal properties such as neurostimulation, immunomodulation, anti-inflammation, anti-oxidation, anti-proliferation, anti-diabetes and especially antiviral activity. Human immunodeficiency virus type-1 (HIV-1) needs the HIV-1 protease (PR) and reverse transcriptase (RT) for its replication. Therefore, both HIV-1 PR and RT are important targets for antiretroviral drug development.

Experimental procedure

The crude hexane (LRH), ethanol (LRE) and water (LRW) extracts of LR were in vitro screened for inhibitory activity against HIV-1 PR and RT, then anti-HIV-1 activity on the infected MOLT-4 cells were determined. Chemical constituents of the extracts were identified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC)-MS. The identified compounds were in silico analysed for drug-likeness property and molecular modelling.

Results and conclusion

According to our screening assays, LRE and LRW significantly inhibited both enzymes (25–55%), while LRH suppressed only the HIV-1 PR activity (88.97%). At 0.5 mg/ml of LRW showed significant inhibition of HIV-1 induced syncytial formation and p24 production in the infected MOLT-4 cells. Investigation of chemical analysis revealed that major groups of identified constituents found in the extracts were fatty acids, peptides and terpenoids. In silico analysis showed that heliantriol F and 6 alpha-fluoroprogesterone displayed great binding energies with HIV-1 PR and HIV-1 RT, respectively. These findings suggest that LR could be a potential source of compounds to inhibit HIV-1 PR and/or RT activities in vitro. Furthermore, our results provide beneficial data for the development of novel HIV-1 PR and RT inhibitors.

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The hexane extract of L. rhinocerus strongly inhibited HIV-1 PR activity.

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The ethanol and water extracts of L. rhinocerus showed HIV-1 PR and RT inhibitions.

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Chemical constituents of L. rhinocerus could block HIV-1 PR and RT in silico studies.

Glycyrrhizic acid as a multifunctional drug carrier - From physicochemical properties to biomedical applications: A modern insight on the ancient drug

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Glycyrrhizic acid (GA), saponin of licorice shows wide range of biological activity.

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Mechanism of GA activity on the cell and molecular level is rarely discussed.

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GA activity could be caused by the cell membrane modification.

Glycyrrhizic acid is the main active component of Licorice root which has been known in traditional Chinese and Japanese medicine since ancient times. In these cultures glycyrrhizic acid (GA) is one of the most frequently used drugs. However, only in 21-st century a novel unusual property of the GA to enhance the activity of other drugs has been discovered. The review describes briefly the experimental evidences of wide spectrum of own biological activities of glycyrrhizic acid as well as discusses the possible mechanisms of the ability of GA to enhance the activity of other drugs. We have shown that due to its amphiphilic nature GA is able to form self-associates in aqueous and non-aqueous media, as well as water soluble complexes with a wide range of lipophilic drugs. The main purpose of our review is to focus reader's attention on physicochemical studies of the molecular mechanisms of GA activity as a drug delivery system (DDS). In our opinion, the most intriguing feature of glycyrrhizic acid which might be the key factor in its therapeutic activity is the ability of GA to incorporate into the lipid bilayer and to increase the membrane fluidity and permeability. The ability of biomolecules and their aggregates to change the properties of cell membranes is of great significance, from both fundamental and practical points of view.

A Novel β-Glucuronidase from Talaromyces pinophilus Li-93 Precisely Hydrolyzes Glycyrrhizin into Glycyrrhetinic Acid 3-O-Mono-β-d-Glucuronide

Glycyrrhetinic acid 3-O-mono-β-d-glucuronide (GAMG), which possesses a higher sweetness and stronger pharmacological activity than those of glycyrrhizin (GL), can be obtained by removal of the distal glucuronic acid (GlcA) from GL. In this study, we isolated a β-glucuronidase (TpGUS79A) from the filamentous fungus Talaromyces pinophilus Li-93 that can specifically and precisely convert GL to GAMG without the formation of the by-product glycyrrhetinic acid (GA) from the further hydrolysis of GAMG. First, TpGUS79A was purified and identified through matrix-assisted laser desorption ionization-tandem time of flight mass spectrometry (MALDI-TOF-TOF MS) and deglycosylation, indicating that TpGUS79A is a highly N-glycosylated monomeric protein with a molecular mass of around 85 kDa, including around 25 kDa of glycan moiety. The gene for TpGUS79A was then cloned and verified by heterologous expression in Pichia pastoris TpGUS79A belonged to glycoside hydrolase family 79 (GH79) but shared low amino acid sequence identity (<35%) with the available GH79 GUS enzymes. TpGUS79A had strict specificity toward the glycan moiety but poor specificity toward the aglycone moiety. Interestingly, TpGUS79A recognized and hydrolyzed the distal glucuronic bond of GL but could not cleave the glucuronic bond in GAMG. TpGUS79A showed a much higher catalytic efficiency on GL (k_cat/K_m of 11.14 mM^-1 s^-1) than on the artificial substrate pNP β-glucopyranosiduronic acid (k_cat/K_m of 0.01 mM^-1 s^-1), which is different from the case for most GUSs. Homology modeling, substrate docking, and sequence alignment were employed to identify the key residues for substrate recognition. Finally, a fed-batch fermentation in a 150-liter fermentor was established to prepare GAMG through GL hydrolysis by T. pinophilus Li-93. Therefore, TpGUS79A is potentially a powerful biocatalyst for environmentally friendly and cost-effective production of GAMG.IMPORTANCE Compared to chemical methods, the biotransformation of glycyrrhizin (GL) into glycyrrhetinic acid 3-O-mono-β-d-glucuronide (GAMG), which has a higher sweetness and stronger pharmacological activity than those of GL, via catalysis by β-glucuronidase is an environmentally friendly approach due to the mild reaction conditions and the high yield of GAMG. However, currently available GUSs show low substrate specificity toward GL and further hydrolyze GAMG to glycyrrhetinic acid (GA) as a by-product, increasing the difficulty of subsequent separation and purification. In the present study, we succeeded in isolating a novel β-glucuronidase (named TpGUS79A) from Talaromyces pinophilus Li-93 that specifically hydrolyzes GL to GAMG without the formation of GA. TpGUS79A also shows higher activity on GL than those of the previously characterized GUSs. Moreover, the gene for TpGUS79A was cloned and its function verified by heterologous expression in P. pastoris Therefore, TpGUS79A can serve as a powerful biocatalyst for the cost-effective production of GAMG through GL transformation.

[Glycyrrhetinic acid selectively inhibits proliferation of hepatocellular carcinoma cells in vitro]

OBJECTIVE

To investigate the selective inhibitory effect of glycyrrhetinic acid on 4 hepatocellular carcinoma (HCC) cells with different proliferation rates and explore the underlying mechanisms.

METHODS

MTT method was used to detect the proliferation rates of 4 HCC cell lines, namely SMMC-7721, SK-HEP1, HEPG2 and HEP3B. Following treatment of the cells with glycyrrhetinic acid (5, 10, 20, 30, 40, and 60 µmol/L), the cell viability was analyzed using MTT assay and the expressions of total ERK protein, p-ERK protein and topoisomerase IIα were detected using Western blotting.

RESULTS

Among the 4 cell lines, SMMC-7721 had the lowest and SK-HEP1 had the highest proliferation rate. Treatment with glycyrrhetinic acid for 48 h dose-dependently inhibited the proliferation of all the 4 cell lines in vitro and produced the strongest inhibitory effect in SMMC-7721 cells with the IC₅₀ of 28.04 µmol/L. The proliferation rate of the cells was positively correlated with the expression levels of p-ERK and topoisomerase IIα, which were the lowest in SMMC-7721 cells and the highest in SK-HEP1 cells. Treatment with 50 µmol/L glycyrrhetinic acid significantly down-regulated the expressions of p-ERK and topoisomerase IIα in the 4 HCC cell lines (P<0.05), while 25 µmol/L glycyrrhetinic acid significantly reduced the expression of topoisomerase IIα and p-ERK in SMMC-7721, HEPG2 and HEP3B cells (P<0.05) but not in SK-HEP1 cells.

CONCLUSION

Glycyrrhetinic acid can inhibit the proliferation of different HCC cells particularly in cells with a low proliferation rate. The inhibitory effect of glycyrrhetinic acid might be mediated by reducing the expressions of topoisomerase IIα and inhibiting the ERK pathway.

Effect of two glycyrrhizinic acid nanoparticle carriers on MARC-145 cells actin filaments

The development of technologies that combine the advantages of nanomedicine with natural medicine represents a versatile approach to improve the safety and efficacy of drugs. Glycyrrhizinic acid (GA) is a natural compound that has a wide range of biological activities for the treatment of diseases. To establish a safe nanotransport system for this drug, two different nanoparticles with glycyrrhizinic acid, solid lipid nanoparticles (SLN-GA) and polymeric nanoparticles (PNPS-GA) were elaborated to obtain nanostructure sizes between 200 and 300 nm. The nanoparticles were evaluated at concentrations of 1.25-100 μl/ml using the MARC-145 cell line to determine the effects on cell morphology, cellular structure (actin filaments) and cell viability (mitochondrial and lysosomal) at 24 and 72 h post-exposure. The safety range of the nanoparticles was 50 µl/ml, to determine that PNPs-GA had an optimal safety profile and no cytotoxic effects, as there was no evidence of changes in morphology, internal cellular structures (stress fibers and the cell cortex formed by actin filaments) or viability under the experimental concentrations and conditions employed.

Preventive Effect of α-Tocopherol and Glycyrrhizin against Platelet-Neutrophil Complex Formation Induced by Hemodialysis Membranes

Background

The intradialytic activation of leukocytes is a major cause of hemodialysis (HD)-associated complications. Contact between blood and HD membranes frequently induces the formation of microaggregates composed of activated platelets and leukocytes, causing leukocyte activation that includes the generation of reactive oxygen species (ROS). This complex formation is mediated primarily by the interaction between P-selectin on activated platelets and its counter-ligands on leukocytes.

Objective

We examined the preventive effects of α-tocopherol and glycyrrhizin in vitro against platelet-neutrophil microaggregate formation and neutrophil ROS production induced by HD membranes.

Methods and Results

Microaggregate formation induced by the incubation of heparinized whole blood with polysulfone (PS) HD membranes was effectively inhibited by α-tocopherol and glycyrrhizin. α-Tocopherol, but not glycyrrhizin, was found to inhibit PS membrane-induced P-selectin expression on the platelet surface; however, glycyrrhizin did inhibit both the formation of neutrophil-platelet microaggregates induced by adenosine diphosphate (ADP) and the adhesion of HL60 leukemic cells to P-selectin-expressing Chinese hamster ovary (CHO) cells, suggesting that glycyrrhizin acts as a competitive inhibitor of P-selectin-mediated cell adhesion. Finally, these compounds almost completely abrogated PS membrane-induced and platelet-dependent ROS production by neutrophils.

Conclusions

These results suggest that α-tocopherol and glycyrrhizin may function as preventive agents of HD-associated leukocyte activation though the modulation of platelet-leukocyte interaction.

Soloxolone methyl inhibits influenza virus replication and reduces virus-induced lung inflammation

Highly pathogenic influenza viruses pose a serious public health threat to humans. Although vaccines are available, new antivirals are needed to efficiently control disease progression and virus transmission due to the emergence of drug-resistant viral strains. In this study, we describe the anti-viral properties of Soloxolone methyl (SM) (methyl 2-cyano-3,12-dioxo-18βH-olean-9(11),1(2)-dien-30-oate, a chemical derivative of glycyrrhetinic acid) against the flu virus. Anti-flu efficacy studies revealed that SM exhibits antiviral activity against the H1N1 influenza A virus in a dose-dependent manner causing a more than 10-fold decrease in virus titer and a reduction in the expression of NP and M2 viral proteins. In a time-of-addition study, SM was found to act at an early stage of infection to exhibit an inhibitory effect on both the attachment step and virus uptake into cells. Also, in infected cells SM downregulates the expression of the inflammatory cytokines IL-6 and TNF-α. In infected mice, SM administered intranasally prior to and after infection significantly decreases virus titers in the lung and prevents post-challenge pneumonia. Together, these results suggest that Soloxolone methyl might serve as an effective therapeutic agent to manage influenza outbreaks and virus-associated complications, and further preclinical and clinical investigation may be warranted.

Lipids in infectious diseases - The case of AIDS and tuberculosis

Lipids play a central role in many infectious diseases. AIDS (Acquired Immune Deficiency Syndrome) and tuberculosis are two of the deadliest infectious diseases to have struck mankind. The pathogens responsible for these diseases, Human Immunodeficiency Virus-1 and Mycobacterium tuberculosis, rely on lipids and on lipid membrane properties to gain access to their host cells, to persist in them and ultimately to egress from their hosts. In this Review, we discuss the life cycles of these pathogens and the roles played by lipids and membranes. We then give an overview of therapies that target lipid metabolism, modulate host membrane properties or implement lipid-based drug delivery systems. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Cryptoporic acid E from Cryptoporus volvatus inhibits influenza virus replication in vitro

Influenza virus infection is a global public health issue. The efficacy of antiviral agents for influenza virus has been limited by the emergence of drug-resistant virus strains. Thus, there is an urgent need to identify novel antiviral therapies. Our previous studies have found that Cryptoporus volvatus extract can potently inhibit influenza virus replication in vitro and in vivo. However, the effective component of Cryptoporus volvatus, which mediates the antiviral activity, hasn't been identified. Here, we identified a novel anti-influenza virus molecule, Cryptoporic acid E (CAE), from Cryptoporus volvatus. Our results showed that CAE had broad-spectrum anti-influenza activity against 2009 pandemic strain A/Beijing/07/2009 (H1N1/09pdm), seasonal strain A/Beijing/CAS0001/2007(H3N2), mouse adapted strains A/WSN/33 (H1N1), and A/PR8/34 (H1N1). We further investigated the mode of CAE action. Time-course-analysis indicated that CAE exerted its inhibition mainly at the middle stages of the replication cycle of influenza virus. Subsequently, we confirmed that CAE inhibited influenza virus RNA polymerase activity and blocked virus RNA replication and transcription in MDCK cells. In addition, we found that CAE also impaired influenza virus infectivity by directly targeting virus particles. Our data suggest that CAE is a major effective component of Cryptoporus volvatus.

Progress of small molecular inhibitors in the development of anti-influenza virus agents

The influenza pandemic is a major threat to human health, and highly aggressive strains such as H1N1, H5N1 and H7N9 have emphasized the need for therapeutic strategies to combat these pathogens. Influenza anti-viral agents, especially active small molecular inhibitors play important roles in controlling pandemics while vaccines are developed. Currently, only a few drugs, which function as influenza neuraminidase (NA) inhibitors and M2 ion channel protein inhibitors, are approved in clinical. However, the acquired resistance against current anti-influenza drugs and the emerging mutations of influenza virus itself remain the major challenging unmet medical needs for influenza treatment. It is highly desirable to identify novel anti-influenza agents. This paper reviews the progress of small molecular inhibitors act as antiviral agents, which include hemagglutinin (HA) inhibitors, RNA-dependent RNA polymerase (RdRp) inhibitors, NA inhibitors and M2 ion channel protein inhibitors etc. Moreover, we also summarize new, recently reported potential targets and discuss strategies for the development of new anti-influenza virus drugs.

Anti-Influenza Treatment: Drugs Currently Used and Under Development

La gripe es una enfermedad contagiosa altamente prevalente y con significativa morbimortalidad. El tratamiento disponible con fármacos antivirales, de ser administrado de forma precoz, puede reducir el riesgo de complicaciones severas; sin embargo, muchos tipos de virus desarrollan resistencia a estos fármacos, reduciendo notablemente su efectividad. Ha habido un gran interés en el desarrollo de nuevas opciones terapéuticas para combatir la enfermedad. Una gran variedad de fármacos han demostrado tener actividad antiinfluenza, pero aún no están disponibles para su uso en la clínica. Muchos de ellos tienen como objetivo componentes del virus, mientras que otros son dirigidos a elementos de la célula huésped que participan en el ciclo viral. Modular los componentes del huésped es una estrategia que minimiza el desarrollo de cepas resistentes, dado que estos no están sujetos a la variabilidad genética que tiene el virus. Por otro lado, la principal desventaja es que existe un mayor riesgo de efectos secundarios asociados al tratamiento. El objetivo de la presente revisión es describir los principales agentes farmacológicos disponibles en la actualidad, así como los nuevos fármacos en estudio con potencial beneficio en el tratamiento de la gripe.

The Neuroprotective Effect of Glycyrrhizic Acid on an Experimental Model of Focal Cerebral Ischemia in Rats

Cerebral ischemia is still one of the most important topics in neurosciences. Our study aimed to investigate the neuroprotective and anti-oxidant effects of glycyrrhizic acid on focal cerebral ischemia in rats. Twenty-four rats were divided equally into three groups. A middle cerebral artery occlusion model was performed in this study where sham and glycyrrhizic acid were administered intraperitoneally following middle cerebral artery occlusion. Group I was evaluated as control. Malondialdehyde (MDA), superoxide dismutase (SOD), and nuclear respiratory factor-1 (NRF1) levels were analyzed biochemically on the right cerebral hemisphere, while ischemic histopathological studies were completed to investigate the anti-oxidant status. Biochemical results showed that SOD and NRF1 levels were significantly increased in the glycyrrhizic acid group compared with the sham group while MDA levels were significantly decreased. On histopathological examination, cerebral edema, vacuolization, degeneration, and destruction of neurons were decreased in the glycyrrhizic acid group compared with the sham group. Cerebral ischemia was attenuated by glycyrrhizic acid administration. These observations indicate that glycyrrhizic acid may have potential as a therapeutic agent in cerebral ischemia by preventing oxidative stress.

Nanomedicine for Infectious Disease Applications: Innovation towards Broad-Spectrum Treatment of Viral Infections

Nanomedicine enables unique diagnostic and therapeutic capabilities to tackle problems in clinical medicine. As multifunctional agents with programmable properties, nanomedicines are poised to revolutionize treatment strategies. This promise is especially evident for infectious disease applications, for which the continual emergence, re-emergence, and evolution of pathogens has proven difficult to counter by conventional approaches. Herein, a conceptual framework is presented that envisions possible routes for the development of nanomedicines as superior broad-spectrum antiviral agents against enveloped viruses. With lipid membranes playing a critical role in the life cycle of medically important enveloped viruses including HIV, influenza, and Ebola, cellular and viral membrane interfaces are ideal elements to incorporate into broad-spectrum antiviral strategies. Examples are presented that demonstrate how nanomedicine strategies inspired by lipid membranes enable a wide range of targeting opportunities to gain control of critical stages in the virus life cycle through either direct or indirect approaches involving membrane interfaces. The capabilities can be realized by enabling new inhibitory functions or improving the function of existing drugs through nanotechnology-enabled solutions. With these exciting opportunities, due attention is also given to the clinical translation of nanomedicines for infectious disease applications, especially as pharmaceutical drug-discovery pipelines demand new routes of innovation.

Characterization of the inhibitory effect of an extract of Prunella vulgaris on Ebola virus glycoprotein (GP)-mediated virus entry and infection

Currently, no approved antiviral therapeutic is available for treatment or prevention of Ebola virus (EBOV) infection. In this study, we characterized an EBOV-glycoprotein (GP) pseudotyped HIV-1-based vector system in different cell cultures, including human umbilical vein endothelial cells (HUVECs) and human macrophages, for the screening of anti-EBOV-GP agent(s). Based on this system, we demonstrated that an aqueous extract (CHPV) from the Chinese herb Prunella vulgaris displayed a potent inhibitory effect on EBOV-GP pseudotyped virus (EBOV-GP-V)-mediated infection in various cell lines, including HUVEC and macrophage. In addition, our results indicated that CHPV was able to block an eGFP-expressing Zaire ebola virus (eGFP-ZEBOV) infection in VeroE6 cells. The anti-EBOV activity of CHPV was exhibited in a dose-dependent manner. At a 12.5 μg/ml concentration, the CHPV showed a greater than 80% inhibition of EBOV-GP-V and eGFP-EBOV infections. Likewise, our studies suggested that the inhibitory effect of CHPV occurred by binding directly to EBOV-GP-Vs and blocking the early viral events. Interestingly, our results have shown that CHPV was able to enhance the anti-EBOV activity of the monoclonal antibody MAb 2G4 against EBOV-GP. Overall, this study provides evidence that CHPV has anti-EBOV activity and may be developed as a novel antiviral approach against EBOV infection.