Antiviral activity of silymarin and baicalein against dengue virus

Baicalein inhibits PRRSV through direct binding, targeting EGFR, and enhancing immune response

Porcine reproductive and respiratory syndrome virus (PRRSV) presents significant economic challenges to the global pork industry due to its ability to mutate rapidly. The current commercial vaccines have limited effectiveness, and there are strict restrictions on the use of antiviral chemical drugs. Therefore, it is urgent to identify new strategies for preventing and controlling PRRSV infections. Baicalein, a flavonoid derived from Scutellaria baicalensis, has gained attention for its potential antiviral properties. However, there is little information about the effects and mechanisms of baicalein in relation to PRRSV. In this study, a network pharmacology analysis identified seven potential targets of baicalein against PRRSV, with the epidermal growth factor receptor (EGFR) emerging as the core target. The results of molecular docking and dynamics (MD) simulations confirmed that baicalein has a high binding affinity for EGFR, with a measured value of - 7.935 kcal/mol. Additionally, both in vitro (EC50 = 10.20 μg/mL) and in vivo (2.41 mg/kg) experiments were conducted to assess the effectiveness of baicalein against PRRSV. Notably, baicalein was found to inhibit various stages of the PRRSV replication cycle and could directly bind to PRRSV in vitro. Baicalein inhibited the entry of PRRSV by blocking EGFR phosphorylation and the downstream PI3K-AKT signaling pathway. This was confirmed by a decrease in the expression of p-EGFR/EGFR, p-AKT/AKT, PI3K, and SRC following treatment with baicalein. Additionally, baicalein significantly enhanced the immune response in piglets infected with PRRSV. In conclusion, this study suggests that baicalein may be a promising pharmaceutical candidate for preventing and controlling PRRS, offering new insights into the antiviral potential of Chinese herbal medicine.

The increasing importance of Dengue virus infection in Saudi Arabia: A review

Exacerbated by the rise of global warming due to climate change, as well as ease of international travel and mass migration, the dengue virus infection remains of particular economic and global concern. Of note, the emergence of the first case of dengue viral infection occurred in Saudi Arabia in the 1990s, and since then there has been a steady rise in the number of cases. Moreover, the arrival of imported dengue virus variants poses a significant challenge to dengue fever surveillance and control efforts within the region, especially as Saudi Arabia attracts millions of religious pilgrims throughout the year. Herein, we discuss the epidemiology of dengue viral infection in Saudi Arabia, dengue fever biology and clinical manifestation. Current management strategies, amongst other factors influencing dengue fever in Saudi Arabia are also deliberated upon. Future ongoing research and consistent monitoring of both established and emerging dengue viral strains within Saudi Arabia are needed, given the lack of current comprehensive studies.

Natural Compounds and Their Analogs as Antivirals Against Dengue Virus: A Review

Dengue virus (DENV) continues to pose a significant global health challenge, causing diseases such as dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. While efforts in vaccine development and antiviral drug discovery are ongoing, effective therapeutic options remain limited. In this review, we highlight natural compounds and the analogs that demonstrated antiviral activity against DENV in in vitro and in vivo studies. Specifically, these studies examine alkaloids, phenolic acids, phenols, flavonoids, terpenoids, and glycosides which have shown potential in inhibiting DENV entry, replication, and reducing the cytokine storm. By focusing on these bioactive compounds and the analogs, a comprehensive overview of their promising roles is provided to advance therapeutic strategies for combating DENV infection.

The Antiviral Effects of Heat-Killed Lactococcus lactis Strain Plasma Against Dengue, Chikungunya, and Zika Viruses in Humans by Upregulating the IFN-α Signaling Pathway

The growing risk of contracting viral infections due to high-density populations and ecological disruptions, such as climate change and increased population mobility, has highlighted the necessity for effective antiviral treatment and preventive measures against Dengue virus (DENV), Chikungunya virus (CHIKV), and Zika virus (ZIKV). Recently, there has been increasing attention on the use of probiotics as a potential antiviral option to reduce virus infections. The present study aimed to assess the immunomodulatory effects of heat-killed Lactococcus lactis strain plasma (LC-Plasma) on peripheral blood mononuclear cells (PBMCs) and its subsequent antiviral response against DENV, CHIKV, and ZIKV. To evaluate the immunomodulatory effects of LC-Plasma on PBMCs isolated from healthy individuals, PBMCs were cultured at a density of 2 × 105 cells/well and stimulated with 10 µg/mL of LC-Plasma. LC-plasma-stimulated PBMCs demonstrated elevated interferon-alpha (IFN-α) production and cluster of differentiation 86 (CD86) and human leukocyte antigen-DR isotype (HLA-DR) upregulation, potentially linked to plasmacytoid dendritic cell (pDC) activation. The replication of DENV, CHIKV, and ZIKV was dose-dependently inhibited when Huh-7 cells were stimulated with LC-Plasma-stimulated PBMC supernatant (LCP Sup). IFN-stimulated gene (ISG) expression, including IFN-stimulated gene 15 (ISG15), IFN-stimulated exonuclease gene 20 (ISG20), IFN-induced transmembrane protein 1 (IFITM-1), myxovirus resistance protein A (MxA), and radical S-adenosyl methionine domain-containing protein 2 (RSAD2), was significantly upregulated in LCP Sup-stimulated Huh-7 cells. Findings from this study indicate that LC-Plasma has the potential to induce IFN-α production, leading to an enhancement in the expression of ISGs and contributing to a broad-spectrum antiviral response. Thus, LC-Plasma may serve as a rational adjunctive treatment to ameliorate viral diseases, warranting future clinical trials.

Inhibitory peptides derived from Hepatitis C virus NS5A for reducing clinical symptoms of dengue virus infection

Lethal Dengue Hemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS) caused by Dengue virus (DENV) infection necessitate the development of effective treatments. Peptides derived from the N-terminal amphipathic α-helix of hepatitis C virus (HCV) NS5A exhibit antiviral activity by disrupting liposomes with high curvatures, such as virus envelopes. This study engineered five peptides from HCV genotype 3a NS5A N-terminal α-helix and screened them for neutralizing efficacy against three DENV serotypes. Two peptides, 3a 3/20 and DS-05, showed superior therapeutic efficacy against DENV and were further evaluated in treating DHF/DSS induced by mouse-adapted DENV infection. Administration of 3a 3/20 and DS-05 post-infection significantly improved mortality and weight loss associated with DHF/DSS in AG6 mice. These peptides reduced viral load in internal organs and viremia to levels comparable with the positive control drug, JNJ-A07, a DENV NS3-NS4B inhibitor. Additionally, they attenuated the cytokine storm in the blood and expression of inflammatory cytokines in internal organ tissues, ameliorating liver and kidney dysfunction after DENV infection. Histopathological analysis revealed significant suppression of damages in internal organs. These findings suggest that the 3a 3/20 and DS-05 peptides improve clinical symptoms of DHF/DSS induced by DENV infection, indicating their potential for clinical application.

A comprehensive overview on antiviral effects of baicalein and its glucuronide derivative baicalin

Natural product-based antiviral candidates have received significant attention. However, there is a lack of sufficient research in the field of antivirals to effectively combat patterns of drug resistance. Baicalein and its glucuronide derivative baicalin are two main components extracted from Scutellaria baicalensis Georgi. They have proven to be effective against a broad range of viruses by directly killing virus particles, protecting infected cells, and targeting viral antigens on their surface, among other mechanisms. As natural products, they both possess the advantage of lower toxicity, enhanced therapeutic efficacy, and even antagonistic effects against drug-resistant viral strains. Baicalein and baicalin exhibit promising potential as potent pharmacophore scaffolds, demonstrating their antiviral properties. However, to date, no review on the antiviral effects of baicalein and baicalin has been published. This review summarizes the recent research progress on antiviral effects of baicalein and baicalin against various types of viruses both in vitro and in vivo with a focus on the dosages and underlying mechanisms. The aim is to provide a basis for the rational development and utilization of baicalein and baicalin, as well as to promote antiviral drug research. Please cite this article as: Liu XY, Xie W, Zhou HY, Zhang HQ, Jin YS. A comprehensive overview on antiviral effects of baicalein and its glucuronide derivative baicalin. J Integr Med. 2024; 22(6): 621-636.

Establishment of in-house assay for screening of anti-SARS-CoV-2 protein inhibitors

Developing a potent antiviral agent to combat Coronavirus Disease-19 (COVID-19) is of critical importance as we may be at risk of the emergence of new virus strains or another pandemic recurrence. The interaction between the SARS-CoV-2 spike protein and Angiotensin Converting Enzyme 2 (ACE2) is the main protein-protein interaction (PPI) implicated in the virus entry into the host cells. Spike-ACE2 PPI represents a major target for drug intervention. We have repurposed a previously described protein-protein interaction detection method to be utilized as a drug screening assay. The assay was standardized using Chitosan nanoparticles (CNPs) as the drug and SARS-CoV-2 spike-ACE2 interaction as the PPI model. The assay was then used to screen four natural bioactive compounds: Curcumin (Cur), Gallic acid (GA), Quercetin (Q), and Silymarin (Sil), and their cytotoxicity was evaluated in vitro. Production of the spike protein and the evaluation of its activity in comparison to a standard commercial protein was part of our work as well. Here we describe a novel simple immunofluorescent screening assay to identify potential SARS-CoV-2 inhibitors that could assess the inhibitory effect of any ligand against any PPI.

Development of Fusion-Based Assay as a Drug Screening Platform for Nipah Virus Utilizing Baculovirus Expression Vector System

Nipah virus (NiV) is known to be a highly pathogenic zoonotic virus, which is included in the World Health Organization Research & Development Blueprint list of priority diseases with up to 70% mortality rate. Due to its high pathogenicity and outbreak potency, a therapeutic countermeasure against NiV is urgently needed. As NiV needs to be handled within a Biological Safety Level (BSL) 4 facility, we had developed a safe drug screening platform utilizing a baculovirus expression vector system (BEVS) based on a NiV-induced syncytium formation that could be handled within a BSL-1 facility. To reconstruct the NiV-induced syncytium formation in BEVS, two baculoviruses were generated to express recombinant proteins that are responsible for inducing the syncytium formation, including one baculovirus exhibiting co-expressed NiV fusion protein (NiV-F) and NiV attachment glycoprotein (NiV-G) and another exhibiting human EphrinB2 protein. Interestingly, syncytium formation was observed in infected insect cells when the medium was modified to have a lower pH level and supplemented with cholesterol. Fusion inhibitory properties of several compounds, such as phytochemicals and a polysulfonated naphthylamine compound, were evaluated using this platform. Among these compounds, suramin showed the highest fusion inhibitory activity against NiV-induced syncytium in the baculovirus expression system. Moreover, our in silico results provide a molecular-level glimpse of suramin's interaction with NiV-G's central hole and EphrinB2's G-H loop, which could be the possible reason for its fusion inhibitory activity.

Current challenges in the discovery of treatments against Mayaro fever

INTRODUCTION

Mayaro fever is an emerging viral disease that manifests as an acute febrile illness. The disease is self-limiting, however joint pain can persist for months leading to chronic arthralgia. There is no specific treatment available, which ultimately leads to socioeconomic losses in populations at risk as well as strains to the public health systems.

AREAS COVERED

We reviewed the candidate treatments proposed for Mayaro virus (MAYV) infection and disease, including antiviral compounds targeting viral or host mechanisms, and pathways involved in disease development and pathogenicity. We assessed compound screening technologies and experimental infection models used in these studies and indicated the advantages and limitations of available technologies and intended therapeutic strategies.

EXPERT OPINION

Although several compounds have been suggested as candidate treatments against MAYV infection, notably those with antiviral activity, most compounds were assessed only in vitro. Compounds rarely progress toin vivo or preclinical studies, and such difficulty may be associated with limited experimental models. MAYV biology is largely inferred from related alphaviruses and reflected by few studies focusing on target proteins or mechanisms of action for MAYV. Therapeutic strategies targeting pathogenic inflammatory responses have shown potential against MAYV-induced disease in vivo, which might reduce long-term sequelae.

Polyphenols from Maackia amurensis Heartwood Protect Neuronal Cells from Oxidative Stress and Prevent Herpetic Infection

Here, we continued the investigation of anti-HSV-1 activity and neuroprotective potential of 14 polyphenolic compounds isolated from Maackia amurensis heartwood. We determined the absolute configurations of asymmetric centers in scirpusin A (13) and maackiazin (10) as 7R,8R and 1″S,2″S, respectively. We showed that dimeric stilbens maackin (9) and scirpusin A (13) possessed the highest anti-HSV-1 activity among polyphenols 1-14. We also studied the effect of polyphenols 9 and 13 on the early stages of HSV-1 infection. Direct interaction with the virus (virucidal activity) was the main mechanism of the antiviral activity of these compounds. The neuroprotective potential of polyphenolic compounds from M. amurensis was studied using models of 6-hydroxydopamine (6-OHDA)-and paraquat (PQ)-induced neurotoxicity. A dimeric stilbene scirpusin A (13) and a flavonoid liquiritigenin (6) were shown to be the most active compounds among the tested polyphenols. These compounds significantly increased the viability of 6-OHDA-and PQ-treated Neuro-2a cells, elevated mitochondrial membrane potential and reduced the intracellular ROS level. We also found that scirpusin A (13), liquiritigenin (6) and retusin (3) considerably increased the percentage of live Neuro-2a cells and decreased the number of early apoptotic cells. Scirpusin A (13) was the most promising compound possessing both anti-HSV-1 activity and neuroprotective potential.

Serum Stabilities and Antiviral Activities of Chemically Modified Peptides Against Dengue Serotypes 1-4

Dengue presents a major public health concern in over 100 countries due to the absence of an effective vaccine and antiviral therapy against all four dengue virus (DENV) serotypes. Several antiviral peptides were previously reported to inhibit at least three or all four DENV serotypes. Chemical modifications such as d-amino acid substitutions, polyethylene glycol (PEG)ylation, and cyclization could be applied to peptides to improve their biological activities and stability in serum. The PEGylated peptide 3 (PEG-P3) was identified to be the most promising antiviral candidate as it demonstrated good inhibitory effects against all four DENV serotypes during the pre- and post-infection stages, Based on the RP-HPLC and LC/MS analysis, peptide 4 was identified to be more stable in human serum than peptide 3, with 78.9 % and 41.6 % of the peptides remaining after 72 h of incubation in human serum, respectively. Both peptides were also able to retain their antiviral activities against specific DENV serotypes after 72 h incubation in human serum. PEG-P3 was found to be more stable than the unmodified peptide 3 with 89.4 % of PEG-P3 remaining in the human serum after 72 h of incubation. PEG-P3 was able to retain its inhibitory effects against DENV-1 to 4 after 72 h of incubation in human serum. This study provided insights into the antiviral activities and stabilities of the unmodified and chemically modified peptides in human serum.

Aminopyrimidine Derivatives as Multiflavivirus Antiviral Compounds Identified from a Consensus Virtual Screening Approach

Around three billion people are at risk of infection by the dengue virus (DENV) and potentially other flaviviruses. Worldwide outbreaks of DENV, Zika virus (ZIKV), and yellow fever virus (YFV), the lack of antiviral drugs, and limitations on vaccine usage emphasize the need for novel antiviral research. Here, we propose a consensus virtual screening approach to discover potential protease inhibitors (NS3pro) against different flavivirus. We employed an in silico combination of a hologram quantitative structure-activity relationship (HQSAR) model and molecular docking on characterized binding sites followed by molecular dynamics (MD) simulations, which filtered a data set of 7.6 million compounds to 2,775 hits. Lastly, docking and MD simulations selected six final potential NS3pro inhibitors with stable interactions along the simulations. Five compounds had their antiviral activity confirmed against ZIKV, YFV, DENV-2, and DENV-3 (ranging from 4.21 ± 0.14 to 37.51 ± 0.8 μM), displaying aggregator characteristics for enzymatic inhibition against ZIKV NS3pro (ranging from 28 ± 7 to 70 ± 7 μM). Taken together, the compounds identified in this approach may contribute to the design of promising candidates to treat different flavivirus infections.

Molecular mechanism of ChaiShi JieDu granule in treating dengue based on network pharmacology and molecular docking: A review

Dengue fever is a frequently occurring infectious disease caused by the Dengue virus, prevalent in tropical and subtropical regions. Chaishi Jiedu Granules (CSJD) is an empirical prescription of the Eighth Affiliated Hospital of Guangzhou Medical University in the treatment of dengue fever, which has been widely used in the treatment of dengue fever, and has shown good efficacy in improving the clinical symptoms of patients. This study aims to explore the molecular mechanism of CSJD in treating dengue fever using network pharmacology, molecular docking techniques, and virtual screening methods. The results showed that luteolin, quercetin and other compounds in CSJD could target important targets related to dengue virus, including STAT3, AKT1, TNF, IL-6, and other key genes, thus playing an antiviral role. Among them, luteolin and wogonin in CSJD also inhibited dengue virus replication and reduced inflammation, and showed good binding force with IL-6 and TNF. Therefore, this study provides an important reference for the development of CSJD as a potential drug for dengue fever treatment and a new perspective for research and development in this field.

Anti-Viral Activity of Bioactive Molecules of Silymarin against COVID-19 via In Silico Studies

The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection drove the global coronavirus disease 2019 (COVID-19) pandemic, causing a huge loss of human life and a negative impact on economic development. It is an urgent necessity to explore potential drugs against viruses, such as SARS-CoV-2. Silymarin, a mixture of herb-derived polyphenolic flavonoids extracted from the milk thistle, possesses potent antioxidative, anti-apoptotic, and anti-inflammatory properties. Accumulating research studies have demonstrated the killing activity of silymarin against viruses, such as dengue virus, chikungunya virus, and hepatitis C virus. However, the anti-COVID-19 mechanisms of silymarin remain unclear. In this study, multiple disciplinary approaches and methodologies were applied to evaluate the potential mechanisms of silymarin as an anti-viral agent against SARS-CoV-2 infection. In silico approaches such as molecular docking, network pharmacology, and bioinformatic methods were incorporated to assess the ligand-protein binding properties and analyze the protein-protein interaction network. The DAVID database was used to analyze gene functions, such as the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) enrichment. TCMSP and GeneCards were used to identify drug target genes and COVID-19-related genes. Our results revealed that silymarin compounds, such as silybin A/B and silymonin, displayed triplicate functions against SARS-CoV-2 infection, including directly binding with human angiotensin-converting enzyme 2 (ACE2) to inhibit SARS-CoV-2 entry into the host cells, directly binding with viral proteins RdRp and helicase to inhibit viral replication and proliferation, and regulating host immune response to indirectly inhibit viral infection. Specifically, the targets of silymarin molecules in immune regulation were screened out, such as proinflammatory cytokines TNF and IL-6 and cell growth factors VEGFA and EGF. In addition, the molecular mechanism of drug-target protein interaction was investigated, including the binding pockets of drug molecules in human ACE2 and viral proteins, the formation of hydrogen bonds, hydrophobic interactions, and other drug-protein ligand interactions. Finally, the drug-likeness results of candidate molecules passed the criteria for drug screening. Overall, this study demonstrates the molecular mechanism of silymarin molecules against SARS-CoV-2 infection.

Oxidative stress in pituitary neuroendocrine tumors: Affecting the tumor microenvironment and becoming a new target for pituitary neuroendocrine tumor therapy

Pituitary adenomas (PAs), or pituitary neuroendocrine tumors (PitNETs), are commonly found in the anterior pituitary gland. Although the majority of PitNETs are benign and stable, several tumors have malignant characteristics. The tumor microenvironment (TME) plays an important role in the process of tumorigenesis and is composed of several types of cells. Various cells in the TME are significantly affected by oxidative stress. It has been reported that immunotherapeutic strategies have good effects in several cancers. However, the clinical potential of immunotherapies in PitNETs has not yet been fully discussed. Oxidative stress can regulate PitNET cells and immune cells in the TME, thus affecting the immune status of the TME of PitNETs. Therefore, modulation of oxidative stress-regulated immune cells using a combination of several agents and the immune system to suppress PitNETs is a promising therapeutic direction. In this review, we systematically analyzed the oxidative stress process within PitNET cells and various immune cells to elucidate the potential value of immunotherapy.

The convergent evolution of influenza A virus: Implications, therapeutic strategies and what we need to know

Influenza virus infection, more commonly known as the 'cold flu', is an etiological agent that gives rise to recurrent annual flu and many pandemics. Dated back to the 1918- Spanish Flu, the influenza infection has caused the loss of many human lives and significantly impacted the economy and daily lives. Influenza virus can be classified into four different genera: influenza A-D, with the former two, influenza A and B, relevant to humans. The capacity of antigenic drift and shift in Influenza A has given rise to many novel variants, rendering vaccines and antiviral therapies useless. In light of the emergence of a novel betacoronavirus, the SARS-CoV-2, unravelling the underpinning mechanisms that support the recurrent influenza epidemics and pandemics is essential. Given the symptom similarities between influenza and covid infection, it is crucial to reiterate what we know about the influenza infection. This review aims to describe the origin and evolution of influenza infection. Apart from that, the risk factors entail the implication of co-infections, especially regarding the COVID-19 pandemic is further discussed. In addition, antiviral strategies, including the potential of drug repositioning, are discussed in this context. The diagnostic approach is also critically discussed in an effort to understand better and prepare for upcoming variants and potential influenza pandemics in the future. Lastly, this review encapsulates the challenges in curbing the influenza spread and provides insights for future directions in influenza management.

Scutellaria baicalensis: a promising natural source of antiviral compounds for the treatment of viral diseases

Viruses, the smallest microorganisms, continue to present an escalating threat to human health, being the leading cause of mortality worldwide. Over the decades, although significant progress has been made in the development of therapies and vaccines against viral diseases, the need for effective antiviral interventions remains urgent. This urgency stems from the lack of effective vaccines, the severe side effects associated with current drugs, and the emergence of drug-resistant viral strains. Natural plants, particularly traditionally-used herbs, are often considered an excellent source of medicinal drugs with potent antiviral efficacy, as well as a substantial safety profile. Scutellaria baicalensis, a traditional Chinese medicine, has garnered considerable attention due to its extensive investigation across diverse therapeutic areas and its demonstrated efficacy in both preclinical and clinical trials. In this review, we mainly focused on the potential antiviral activities of ingredients in Scutellaria baicalensis, shedding light on their underlying mechanisms of action and therapeutic applications in the treatment of viral infections.

Elnosary M, L. Ashour M, M. Abd El-Moneam N, A. Shreadah M. Flavonoids Biosynthesis in Plants as a Defense Mechanism: Role and Function Concerning Pharmacodynamics and Pharmacokinetic Properties

Flavonoids are a major class of secondary metabolites that comprises more than 6000 compounds that have been identified. They are biosynthesized via the phenylpropanoid metabolic pathway that involves groups of enzymes such as isomerases, hydroxylases, and reductases that greatly affect the determination of the flavonoid skeleton. For example, transferase enzymes responsible for the modification of sugar result in changes in the physiological activity of the flavonoids and changes in their physical properties, such as solubility, reactivity, and interaction with cellular target molecules, which affect their pharmacodynamics and pharmacokinetic properties. In addition, flavonoids have diverse biological activities such as antioxidants, anticancer, and antiviral in managing Alzheimer’s disease. However, most marine flavonoids are still incompletely discovered because marine flavonoid biosynthesis is produced and possesses unique substitutions that are not commonly found in terrestrial bioactive compounds. The current chapter will illustrate the importance of flavonoids’ role in metabolism and the main difference between marine and terrestrial flavonoids.

A Comprehensive Review of Natural Flavonoids with Anti-SARS-CoV-2 Activity

The COVID-19 pandemic caused by SARS-CoV-2 has majorly impacted public health and economies worldwide. Although several effective vaccines and drugs are now used to prevent and treat COVID-19, natural products, especially flavonoids, showed great therapeutic potential early in the pandemic and thus attracted particular attention. Quercetin, baicalein, baicalin, EGCG (epigallocatechin gallate), and luteolin are among the most studied flavonoids in this field. Flavonoids can directly or indirectly exert antiviral activities, such as the inhibition of virus invasion and the replication and inhibition of viral proteases. In addition, flavonoids can modulate the levels of interferon and proinflammatory factors. We have reviewed the previously reported relevant literature researching the pharmacological anti-SARS-CoV-2 activity of flavonoids where structures, classifications, synthetic pathways, and pharmacological effects are summarized. There is no doubt that flavonoids have great potential in the treatment of COVID-19. However, most of the current research is still in the theoretical stage. More studies are recommended to evaluate the efficacy and safety of flavonoids against SARS-CoV-2.

Development of novel antiviral peptides against dengue serotypes 1-4

Dengue infections pose a critical threat to public health worldwide. Since there are no clinically approved antiviral drugs to treat dengue infections caused by the four dengue virus (DENV) serotypes, there is an urgent need to develop effective antivirals. Peptides are promising antiviral candidates due to their specificity and non-toxic properties. The DENV envelope (E) protein was selected for the design of antiviral peptides due to its importance in receptor binding and viral fusion to the host cell membrane. Twelve novel peptides were designed to mimic regions containing critical amino acid residues of the DENV E protein required for interaction with the host. A total of four peptides were identified to exhibit potent inhibitory effects against at least three or all four DENV serotypes. Peptide 3 demonstrated all three modes of action: cell protection and inhibition of post-infection against all four DENV serotypes, whereas direct virus-inactivating effects were only observed against DENV-2, 3, and 4. Peptide 4 showed good direct virus-inactivating effects against DENV-2 (74.26%) as well as good inhibitions of DENV-1 (80.37%) and DENV-4 (72.22%) during the post-infection stage. Peptide 5 exhibited direct virus-inactivating effects against all four DENV serotypes, albeit at lower inhibition levels against DENV-1 and DENV-3. It also exhibited highly significant inhibition of DENV-4 (89.31%) during post-infection. Truncated peptide 5F which was derived from peptide 5 showed more significant inhibition of DENV-4 (91.58%) during post-infection and good direct virus-inactivating effects against DENV-2 (77.55%) at a lower concentration of 100 μM. Peptide 3 could be considered as the best antiviral candidate for pre- and post-infection treatments of DENV infections in regions with four circulating dengue serotypes. However, if the most predominant dengue serotype for a particular region could be identified, peptides with significantly high antiviral activities against that particular dengue serotype could serve as more suitable antiviral candidates. Thus, peptide 5F serves as a more suitable antiviral candidate for post-infection treatment against DENV-4.

Promising Role of the Scutellaria baicalensis Root Hydroxyflavone-Baicalein in the Prevention and Treatment of Human Diseases

Plant roots, due to a high content of natural antioxidants for many years, have been used in herbal medicine. It has been documented that the extract of Baikal skullcap (Scutellaria baicalensis) has hepatoprotective, calming, antiallergic, and anti-inflammatory properties. Flavonoid compounds found in the extract, including baicalein, have strong antiradical activity, which improves overall health and increases feelings of well-being. Plant-derived bioactive compounds with antioxidant activity have for a long time been used as an alternative source of medicines to treat oxidative stress-related diseases. In this review, we summarized the latest reports on one of the most important aglycones with respect to the pharmacological activity and high content in Baikal skullcap, which is 5,6,7-trihydroxyflavone (baicalein).

Baicalein Alleviates Testicular Ischemia-Reperfusion Injury in a Rat Model of Testicular Torsion-Detorsion

Testicular torsion/detorsion-induced ischemia/reperfusion injury is partly due to the overgeneration of reactive oxygen species. Baicalein, a main bioactive constituent derived from the dried root of Scutellaria baicalensis Georgi, possesses powerful antioxidative and anti-inflammatory properties. Therefore, we designed the research to explore the possible protective effect of baicalein against testicular ischemia-reperfusion injury. Sprague-Dawley rats were randomized into 4 groups, including control, testicular ischemia-reperfusion, testicular ischemia-reperfusion+vehicle injection, and testicular ischemia-reperfusion+baicalein therapy groups. The control group received surgical exposure of the left testis without torsion-detorsion. In the testicular ischemia-reperfusion group, the left testis underwent 720° counterclockwise torsion for two hours and then was allowed detorsion. Rats in the testicular ischemia-reperfusion+vehicle injection group received intraperitoneal injection of the vehicle at detorsion. In the baicalein-treated group, the intraperitoneal administration of baicalein dissolved in the vehicle was performed at detorsion. At four hours or three months following testicular detorsion, testicular tissues were removed to detect the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) which can recruit neutrophils into the testis, myeloperoxidase activity (an index of neutrophil infiltration in the testis), protein expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in neutrophils which can catalyze reactive oxygen species production, malondialdehyde concentration (a common marker of reactive oxygen species), and spermatogenesis. Both testicular ischemia-reperfusion and testicular ischemia-reperfusion+vehicle injection significantly increased the TNF-α and IL-1β levels, myeloperoxidase activity, NADPH oxidase protein expression, and malondialdehyde concentration, while decreased spermatogenesis in ipsilateral testes. In contrast, baicalein administration remarkably reduced TNF-α and IL-1β levels, myeloperoxidase activity, NADPH oxidase protein expression, and malondialdehyde concentration and also elevated spermatogenesis in ipsilateral testes. The results of our experiment demonstrate that baicalein alleviates testicular ischemia-reperfusion injury by inhibiting TNF-α and IL-1β secretion, neutrophil infiltration in the testis, and NADPH oxidase protein expression in neutrophils to reduce reactive oxygen species production.

An update on inhibitors targeting RNA-dependent RNA polymerase for COVID-19 treatment: Promises and challenges

The highly transmissible variants of SARS-CoV-2, the causative pathogen of the COVID-19 pandemic, bring new waves of infection worldwide. Identification of effective therapeutic drugs to combat the COVID-19 pandemic is an urgent global need. RNA-dependent RNA polymerase (RdRp), an essential enzyme for viral RNA replication, is the most promising target for antiviral drug research since it has no counterpart in human cells and shows the highest conservation across coronaviruses. This review summarizes recent progress in studies of RdRp inhibitors, focusing on interactions between these inhibitors and the enzyme complex, based on structural analysis, and their effectiveness. In addition, we propose new possible strategies to address the shortcomings of current inhibitors, which may guide the development of novel efficient inhibitors to combat COVID-19.

Recent two-year advances in anti-dengue small-molecule inhibitors

Dengue is an acute tropical infectious disease transmitted by mosquitoes, which has posed a major challenge to global public health. Unfortunately, there is a lack of clinically proven dengue-specific drugs for its prevention and treatment. As the pathogenesis of dengue has not been fully elucidated, the development of specific drugs is seriously hindered. This article briefly describes the pathogenesis of dengue fever, the molecular characteristics, and epidemiology of dengue virus, and focuses on the potential small-molecule inhibitors of dengue virus, including on-target and multi-targeted inhibitors, which have been reported in the past two years.

Contemporary exploitation of natural products for arthropod-borne pathogen transmission-blocking interventions

An integrated approach to innovatively counter the transmission of various arthropod-borne diseases to humans would benefit from strategies that sustainably limit onward passage of infective life cycle stages of pathogens and parasites to the insect vectors and vice versa. Aiming to accelerate the impetus towards a disease-free world amid the challenges posed by climate change, discovery, mindful exploitation and integration of active natural products in design of pathogen transmission-blocking interventions is of high priority. Herein, we provide a review of natural compounds endowed with blockade potential against transmissible forms of human pathogens reported in the last 2 decades from 2000 to 2021. Finally, we propose various translational strategies that can exploit these pathogen transmission-blocking natural products into design of novel and sustainable disease control interventions. In summary, tapping these compounds will potentially aid in integrated combat mission to reduce disease transmission trends.

Mechanistic Insights into the Pharmacological Significance of Silymarin

Medicinal plants are considered the reservoir of diverse therapeutic agents and have been traditionally employed worldwide to heal various ailments for several decades. Silymarin is a plant-derived mixture of polyphenolic flavonoids originating from the fruits and akenes of Silybum marianum and contains three flavonolignans, silibinins (silybins), silychristin and silydianin, along with taxifolin. Silybins are the major constituents in silymarin with almost 70–80% abundance and are accountable for most of the observed therapeutic activity. Silymarin has also been acknowledged from the ancient period and is utilized in European and Asian systems of traditional medicine for treating various liver disorders. The contemporary literature reveals that silymarin is employed significantly as a neuroprotective, hepatoprotective, cardioprotective, antioxidant, anti-cancer, anti-diabetic, anti-viral, anti-hypertensive, immunomodulator, anti-inflammatory, photoprotective and detoxification agent by targeting various cellular and molecular pathways, including MAPK, mTOR, β-catenin and Akt, different receptors and growth factors, as well as inhibiting numerous enzymes and the gene expression of several apoptotic proteins and inflammatory cytokines. Therefore, the current review aims to recapitulate and update the existing knowledge regarding the pharmacological potential of silymarin as evidenced by vast cellular, animal, and clinical studies, with a particular emphasis on its mechanisms of action.

Synthesis of baicalein derivatives and evaluation of their antiviral activity against arboviruses

Natural plant-derived baicalein which is extracted from Chinese herb Scutellaria baicalensis Georgi belongs to the flavonoid compounds and possesses multiple pharmacological activities. In this study, we designed and synthesized new series of derivatives of baicalein (BE) through catalytic coupling reactions, and screened for their antiviral activity against arboviruses including Chikungunya virus (CHIKV), West Nile virus (WNV) or Zika virus (ZIKV). Our results revealed for the first time that BE and its derivatives had potent anti-CHIKV, anti-WNV and anti-ZIKV effects. And modification of 8 or 4' position could lead to obtain potent antiviral compounds against CHIKV, WNV and ZIKV with lower cytotoxicity. Among the baicalein derivatives, C3 and F3 showed the most potent antiviral activities against CHIKV, WNV and ZIKV, which were 5-10 times more potent than baicalein. Our findings will provide research basis for the development of baicalein derivatives as effective antiviral agents.