Potent Antiviral Activity Research Articles

Screening for Potential Antiviral Compounds from Cyanobacterial Secondary Metabolites Using Machine Learning

The secondary metabolites of seawater and freshwater blue-green algae are a rich natural product pool containing diverse compounds with various functions, including antiviral compounds; however, high-efficiency methods to screen such compounds are lacking. Advanced virtual screening techniques can significantly reduce the time and cost of novel antiviral drug identification. In this study, we used a cyanobacterial secondary metabolite library as an example and trained three models to identify compounds with potential antiviral activity using a machine learning method based on message-passing neural networks. Using this method, 364 potential antiviral compounds were screened from >2000 cyanobacterial secondary metabolites, with amides predominating (area under the receiver operating characteristic curve value: 0.98). To verify the actual effectiveness of the candidate antiviral compounds, HIV virus reverse transcriptase (HIV-1 RT) was selected as a target to evaluate their antiviral potential. Molecular docking experiments demonstrated that candidate compounds, including kororamide, mollamide E, nostopeptolide A3, anachelin-H, and kasumigamide, produced relatively robust non-covalent bonding interactions with the RNase H active site on HIV-1 RT, supporting the effectiveness of the proposed screening model. Our data demonstrate that artificial intelligence-based screening methods are effective tools for mining potential antiviral compounds, which can facilitate the exploration of various natural product libraries.

Structure-Based Design of Covalent SARS-CoV-2 Papain-like Protease Inhibitors.

The COVID-19 pandemic is caused by SARS-CoV-2, a highly transmissible and pathogenic RNA betacoronavirus. Like other RNA viruses, SARS-CoV-2 continues to evolve with or without drug selection pressure, and many variants have emerged since the beginning of the pandemic. The papain-like protease, PLpro, is a cysteine protease that cleaves viral polyproteins as well as ubiquitin and ISG15 modifications from host proteins. Leveraging our recently discovered Val70Ub binding site in PLpro, we designed covalent PLpro inhibitors by connecting cysteine reactive warheads to the biarylphenyl PLpro inhibitors via flexible linkers. Several leads displayed potent enzymatic inhibition (IC50 = 0.1-0.3 μM) and antiviral activity (EC50 = 0.09-0.96 μM). Fumaramide inhibitors Jun13567 (15), Jun13728 (16), and Jun13714 (18) showed favorable in vivo pharmacokinetic properties with intraperitoneal injection. The X-ray crystal structure of PLpro with Jun13567 (15) validated our design strategy, revealing covalent conjugation between the catalytic Cys111 and the fumaramide warhead. The results suggest these covalent PLpro inhibitors are promising SARS-CoV-2 antiviral drug candidates.

Uncovering the Potent Antiviral Activity of the Sesterterpenoids from the Sponge Ircinia Felix Against Human Adenoviruses: from the Natural Source to the Total Synthesis.

Human Adenovirus (HAdV) infections in immunocompromised patients can result in disseminated diseases with high morbidity and mortality rates due to the absence of available treatments for these infections. The sponge Ircinia felix was selected for the significant anti-HAdV activity displayed by its organic extracts. Its chemical analysis yielded three novel sesterterpene lactams, ircinialactams J-L, along with three known sesterterpene furans which structures were established by a deep spectrometric analysis. Ircinialactam J displayed significant antiviral activity against HAdV without significant cytotoxicity, showing an effectiveness 11 times greater than that of the standard treatment, cidofovir®. Comparison of the antiviral evaluation results of the isolated compounds allowed us to deduce some structure-activity relationships. Mechanistic assays suggest that ircinialactam J targets an early step of the HAdV replicative cycle before HAdV genome reaches the nucleus of the host cell. The first total synthesis of ircinialactam J was also accomplished to prove the structure and to provide access to analogues. Key steps are a regio- and stereoselective construction of the trisubstituted Z-olefin at Δ7 by iron-catalyzed carbometallation of a homopropargylic alcohol, a stereoselective methylation to generate the stereogenic center at C18, and the formation of the (Z)-Δ20 by stereoselective aldol condensation to introduce the tetronic acid unit. Ircinialactam J is a promising chemical lead to new potent antiviral drugs against HAdV infections.

Antipathogenic Activity of Betainized Polyethyleneimine Sprays Without Toxicity

Background/Objectives: The design of alternative antipathogenic sprays has recently attracted much attention due to the limitations of existing formulations, such as toxicity and low and narrow efficacy. Polyethyleneimine (PEI) is a great antimicrobial polymer against a wide range of pathogens, but toxicity limits its use. Here, betainized PEI (B-PEI) was synthesized to decrease the toxicity of PEI and protonated with citric acid (CA), boric acid (BA), and HCl to improve antimicrobial activity. Methods: Cytotoxicity of the PEI-based solutions was determined on L929 fibroblast cells. Antibacterial/fungal activity of PEI-based antipathogenic sprays was investigated by microtiter and disc diffusion assays, in addition to bacterial viability and adhesion % of common bacteria and fungi on the PEI-treated masks. Furthermore, the antiviral effect of the PEI-based solutions was determined against SARS-CoV-2 virus. Results: The biosafe concentration of PEI was determined as 1 μg/mL with 75 ± 11% cell viability, but B-PEI and its protonated forms had great biocompatibility even at 1000 μg/mL with more than 85% viability. The antibacterial/fungal effect of non-toxic B-PEI was improved by protonation with BA and HCl with 2.5–10 mg/mL minimum bactericidal/fungicidal concentrations (MBCs/MFCs). Bacterial/fungal viability and adhesion on the mask was almost eliminated by using 50 μL with 5–10 mg/mL of B-PEI-BA. Both protonated bare and betainized PEI show potent antiviral activity against SARS-CoV-2 virus. Conclusions: The toxicity of PEI was overcome by using betainized forms of PEI (B-PEI). Furthermore, the antimicrobial and antiviral efficacy of PEI and B-PEI was improved by protonation with CA, BA, and HCl of amine groups on B-PEI. B-PEI-BA spray solution has great potential as an antipathogenic spray with broad-spectrum antimicrobial potency against harmful bacteria, fungi, and viruses without any toxicity.

EDP-938 Has a High Barrier to Resistance in Healthy Adults Experimentally Infected with Respiratory Syncytial Virus.

EDP-938 is an oral once-daily RSV nucleoprotein (N) inhibitor with potent antiviral activity. In a human RSV challenge trial, EDP-938 significantly reduced viral load and symptom severity. During antiviral development, it is critical to understand the propensity for resistance to develop. In vitro studies of EDP-938 suggest a higher barrier to resistance as compared to RSV fusion inhibitors. We evaluated the development of viral resistance to EDP-938 in a human challenge trial. A subset of the 124 participants with RSV infection were chosen for genetic analysis; 159 nasal wash samples from 48 participants were analyzed using next-generation sequencing of the N gene of RSV. Of the 48 participant sampled, 37 were from EDP-938-treated and 11 were placebo-treated participants, representing 45% and 26% of the participants, respectively. The effects of treatment-emergent mutations on viral load, EDP-938 efficacy, and viral fitness were evaluated. Two of the 37 EDP-938-treated participants with samples sequenced had treatment-emergent mutations: N:L139I and N:E112G. From in vitro analysis, N:L139I reduced sensitivity to EDP-938 by approximately 10-fold, while N:E112G had no effect. However, N:L139I was associated with a reduction in viral fitness, suggesting clinical resistance is associated with fitness costs. Neither of these variants were associated with reduced viral clearance. In human RSV infections treated with EDP-938, emergence of RSV variants with reduced sensitivity to EDP-938 occurred in only 1 participant and was associated with reduced viral fitness. EDP-938's high barrier to resistance highlights its robust mechanism of action. NCT03691623.

Dual effects of ipecac alkaloids with potent antiviral activity against foot-and-mouth disease virus as replicase inhibitors and direct virucides

ABSTRACT Foot-and-Mouth Disease (FMD) is a contagious, blistering disease caused by the Foot-and-Mouth Disease virus (FMDV), which affects livestock globally. Currently, no commercial antiviral agent is available for effective disease control. This study investigated the antiviral potential of natural-derived alkaloids against FMDV in BHK-21 cells. Twelve alkaloids were assessed for their antiviral activities at various stages of FMDV infection, including pre-viral entry, post-viral entry, and prophylactic assays, as well as attachment and penetration assays by evaluating cytopathic effect reduction and directed-virucidal effects. The results showed that ipecac alkaloids, cephaeline (CPL) and emetine (EMT), exhibited dual effects with robust antiviral efficacy by reducing cytopathic effect and inhibiting FMDV replication in a dose-dependent manner. Evaluation through immunoperoxidase monolayer assay and RT-PCR indicated effectiveness at post-viral entry stage, with sub-micromolar EC50 values for CPL and EMT at 0.05 and 0.24 µM, respectively, and high selective indices. Prophylactic effects prevented infection with EC50 values of 0.23 and 0.64 µM, respectively. Directed-virucidal effects demonstrated significant reduction of extracellular FMDV, with CPL exhibiting a dose-dependent effect. Furthermore, the replicase (3Dpol) inhibition activity was identified using the FMDV minigenome assay, which revealed strong inhibition with IC50 values of 0.15 µM for CPL and 4.20 µM for EMT, consistent with the decreased negative-stranded RNA production. Molecular docking confirmed the interaction of CPL and EMT with residues in the active site of FMDV 3Dpol. In conclusion, CPL and EMT exhibited promising efficacy through their dual effects and provide an alternative approach for controlling FMD in livestock.

RpIFN-λ1 alleviates the clinical symptoms of porcine epidemic diarrhea

Porcine epidemic diarrhea (PED), caused by the porcine epidemic diarrhea virus (PEDV), primarily affects the jejunum and ileum of pigs. Interferons, glycoproteins with high species specificity and potent antiviral activity, are crucial in defending against viral infections. Unlike other interferons, interferon-lambda (IFN-λ) mainly acts on mucosal epithelial cells and exhibits robust antiviral activity at mucosal surfaces. However, the high cost limits the use of naturally extracted interferons in farming. In this study, we expressed recombinant porcine interferon-lambda 1 (rpIFN-λ1) in eukaryotic cells, demonstrating effective antiviral activity against PEDV in Vero E6 and IPI-FX cells. In vivo, rpIFN-λ1 alleviated clinical symptoms and intestinal damage, enhanced antioxidant capacity, reduced inflammation, and significantly improved the survival rate of piglets following PEDV infection. Both in vitro and in vivo studies confirmed that rpIFN-λ1 upregulated interferon-stimulated genes (ISGs) via the JAK-STAT pathway, thereby exerting antiviral effects. In conclusion, rpIFN-λ1 significantly inhibited PEDV replication and alleviated clinical symptoms. The selectivity of rpIFN-λ1 for intestinal cells and its ability to reduce viral shedding suggest that this agent is a promising antiviral for enteric viruses such as PEDV. Our findings highlight rpIFN-λ1 as a cost-effective, efficient, and novel strategy for antiviral treatment of PEDV.

An in-depth exploration of ethnomedicinal applications, phytochemical profiles, and pharmacological potentials: unveiling Withania somnifera

Researchers have extensively studied Withania somnifera (L.) Dunal, a woody shrub renowned for its multifaceted medicinal attributes such as antibacterial, anti-inflammatory, adaptogenic, aphrodisiac, and tonifying properties, because of its medicinal and traditional values. However, comprehensive information about its medicinal uses and pharmacological implications is scattered across various sources. Thus, this study aims to provide a comprehensive review of its ethnomedicinal uses, phytochemistry, and pharmacological attributes, consolidating information from diverse data sources. Systematic investigations have revealed the presence of diverse phytochemicals in W. somnifera, including major alkaloids, withanolides, flavonoids, tannins, oils, phytosterols, and amino acids. Extracts, fractions, and bioactive compounds derived from W. somnifera exhibited potent antibacterial, anti-inflammatory, anti-aging, anti-analgesic, anti-cancer, antivenom, anti-fungal, and anti-viral activities. W. somnifera serves as a valuable source of phytochemicals with diverse biological activities, offering significant therapeutic benefits globally. However, further studies are needed to assess potential side effects. Additionally, while several isolated compounds have demonstrated notable bioactivities, future research should focus on elucidating their mechanistic features to facilitate their integration into drug discovery endeavors.

Lithospermic acid inhibits dengue virus infection through binding with envelope proteins

The dengue virus has emerged as a global pandemic, highlighting the urgent need for the immediate development of antiviral therapeutics. Lithospermum erythrorhizon, a medicinal plant commonly used in China for various ailments including viral infections, inflammation, rheumatism, and cancer, showed promising antiviral properties in our research. Specifically, both the ethanol extract of Lithospermum erythrorhizon and its active component, lithospermic acid, demonstrated significant inhibitory effects on Dengue virus (DENV) replication in Vero cells, with EC50 values of 6.50 μg/mL(95% CI: 2.25 to 18.98)and 15.00 μM(95% CI: 12.13 to 18.07), respectively. Notably, lithospermic acid exhibited potent antiviral activity across multiple cell lines against DENV, impeding virus replication and specifically impeding the expression of viral E and NS3 proteins during the early stages of DENV infection. Experimental assays involving RNase digestion and sucrose density gradient analysis confirmed that lithospermic acid did not directly inactivate DENV but rather interfered with viral processes. Furthermore, the compound was found to bind to the E protein of DENV, effectively inhibiting viral infection and mitigating the cytopathic effects induced by DENV. Collectively, these findings underscore the potential of lithospermic acid as a promising candidate for the development of therapeutic strategies targeting DENV infection.

Coumarin-imidazopyridine hybrids and their first-in-class ZnII metal complexes as potent dual entry and replication inhibitors of Zika viral infection

In this study, we synthesized and characterized a series of coumarin-imidazopyridine hybrid ligands (HL1-HL4) and their corresponding Zn(II) complexes (C1-C4). The ligands were synthesized via a two-step process in 56–90 % yields. The resulting ligands, were utilized to form Zn(II) complexes, characterized by conductivity measurements, HRMS, IR, 1H NMR spectroscopy and X-ray diffractions. Biological evaluations revealed that these compounds exhibited potent antiviral activity against Zika virus (ZIKV), with EC50 values ranging from 0.55 to 4.8 µM and SI of up to 1490. Notably, the complexes (the first-in-class Zn(II) anti-ZIKV complexes) generally displayed enhanced activity compared to their respective ligands, with some compounds outperforming the reference antiviral, ribavirin. The Time of Addition assay suggested that while some compounds interfere with both viral entry (with a virucidal component) and replication phases, other only acted in replication phases. These results together with molecular modeling studies on ZIKV Envelope protein and ZIKV NS2B-NS3 offered insights for their mode of actions and further optimizations.

Synthesis and Anticancer Activity Assessment of Zelkovamycin Analogues.

The zelkovamycin family is a class of cyclic octapeptides with potent antibacterial and antiviral activity. Due to their unique chemical structures and excellent bioactivity, zelkovamycins have consistently attracted the interest of synthetic chemists. However, only the total synthesis of zelkovamycin and zelkovamycin G has been reported until now. The current work presents, for the first time, the synthesis of zelkovamycin analogues, along with their anticancer activity assessment. Firstly, the corresponding chain peptide based on the amino acid sequence of zelkovamycin H was synthesized using the Fmoc solid-phase peptide strategy. This was followed by cyclization under high dilution conditions to obtain compound 21, and its structure was elucidated by NMR analysis. The results confirm that compound 21 is not the natural product of zelkovamycin H. We deduced that during the synthesis of peptide 12, the D-Abu residue epimerized to the L-Abu form, leading to the formation of peptide 20, which blocked our efforts during the synthesis of zelkovamycin H. Two more analogues, 22 and 23, were synthesized by changing the structure of amino acid residues using the same strategy. The anticancer activity of analogues 21-23 against Huh-7 cells was evaluated in vitro; however, their IC50 values were >50 μM.

Inhibition of fish rhabdovirus demonstrates application prospect of two methylimidazole phenylpropanoid-based small molecules in aquaculture

Aquaculture faces significant challenges, notably spring viremia of carp (SVC) caused by spring viremia of carp virus (SVCV), which is particularly devastating due to its high mortality rates and rapid transmission among fish populations. This study introduces two novel methylimidazole phenylpropanoid-based small molecules, LML1013 and LML1014, synthesized for combating SVCV in aquaculture environments. Comprehensive in vitro and in vivo evaluations demonstrated that these compounds have potent antiviral activities against SVCV. They effectively inhibited SVCV replication in epithelioma papulosum cyprinid (EPC) cells and significantly reduced mortality rates in infected juvenile common carp. Further analyses revealed that daily administration of these compounds not only blocked SVCV replication but also stimulated the innate immune responses of the fish, thereby enhancing their overall resistance to viral infection. Notably, the antiviral efficacy was observed in a dose- and time-dependent manner without inducing cytotoxic effects, emphasizing their therapeutic potential. The stability of LML1013 and LML1014 in aquacultural water and their ability to prevent horizontal viral transmission were also confirmed, further supporting their feasibility as treatment options in aquaculture. Overall, the development of LML1013 and LML1014 provides a promising strategy for controlling SVCV outbreaks and enhancing the sustainability of fish farming operations. This approach offers significant implications for improving aquaculture biosecurity and effectively managing viral disease threats.

Orally bioavailable RORγ/DHODH dual host-targeting small molecules with broad-spectrum antiviral activity

Host-directed antivirals (HDAs) represent an attractive treatment option and a strategy for pandemic preparedness, especially due to their potential broad-spectrum antiviral activity and high barrier to resistance development. Particularly, dual-targeting HDAs offer a promising approach for antiviral therapy by simultaneously disrupting multiple pathways essential for viral replication.Izumerogant (IMU-935) targets two host proteins, (i) the retinoic acid receptor-related orphan receptor γ isoform 1 (RORγ1), which modulates cellular cholesterol metabolism, and (ii) the enzyme dihydroorotate dehydrogenase (DHODH), which is involved in de novo pyrimidine synthesis. Here, we synthesized optimized derivatives of izumerogant and characterized their antiviral activity in comparison to a recently described structurally distinct RORγ/DHODH dual inhibitor. Cell culture-based infection models for enveloped and non-enveloped DNA and RNA viruses, as well as a retrovirus, demonstrated high potency and broad-spectrum activity against human viral pathogens for RORγ/DHODH dual inhibitors at nanomolar concentrations. Comparative analyses with equipotent single-target inhibitors in metabolite supplementation approaches revealed that the dual-targeting mode represents the mechanistic basis for the potent antiviral activity. For SARS-CoV-2, an optimized dual inhibitor completely blocked viral replication in human airway epithelial cells at 5 nM and displayed a synergistic drug interaction with the nucleoside analog molnupiravir. In a SARS-CoV-2 mouse model, treatment with a dual inhibitor alone, or in combination with molnupiravir, reduced the viral load by 7- and 58-fold, respectively.Considering the clinical safety, oral bioavailability, and tolerability of izumerogant in a recent Phase I study, izumerogant-like drugs represent potent dual-targeting antiviral HDAs with pronounced broad-spectrum activity for further clinical development.

Myrtus communis L. Essential Oil Exhibits Antiviral Activity against Coronaviruses.

Human coronaviruses are a continuous threat to the human population and have limited antiviral treatments, and the recent COVID-19 pandemic sparked interest in finding new antiviral strategies, such as natural products, to combat emerging coronaviruses. Rapid efforts in the scientific community to identify effective antiviral agents for coronaviruses remain a focus to minimize mortalities and global setbacks. In this study, an essential oil derived from Myrtus communis L. (MEO) is effective against HCoV-229E and HCoV-OC43 virus infections in comparison to two FDA-approved drugs, Remdesivir and Nirmatrelvir. Gas-chromatography and mass spectrometry were used to identify the chemical composition of MEO. Slight antioxidant activity was observed in MEO, indicating a role in oxidative stress. A dose-response curve measuring the EC50 indicates a high potency against HCoV-229E and HCoV-OC43 virus infections on Huh7.5 cells with low cytotoxicity using a PrestoBlue cell viability assay. Our findings demonstrate that MEO exhibits potent antiviral activity against HCoV-229E and HCoV-OC43 on Huh7.5 cells within a low-cytotoxicity range, but not on SARS-CoV-2. Artificial bacterial chromosome plasmids that expressed SARS-CoV-2 used for replicon-to determine viral replication and viral assembly/egress on HEK293T/17 cells-and virus-like particles on Huh7.5-AT cells-to determine viral entry and assembly/egress-showed no antiviral activity with MEO in comparison to Remdesivir. This study reveals the potential effectiveness of MEO as an alternative natural remedy to treat human coronaviruses and a potential antiviral agent for future coronavirus infections.

Evaluation of Withania somnifera based supplement for immunomodulatory and antiviral properties against viral infection

BackgroundViral mediated diseases are continuously posing potent threat to human health. Nutraceuticals are being employed as novel therapeutics during viral outbreaks. MAM granules consist of Curcuma longa, Withania somnifera, and Piper nigrum, is one such patented Siddha nutraceutical supplement that has been proposed to be a therapeutic agent against viral diseases. ObjectiveWe characterised MAM for their phytochemical and physicochemical properties and evaluated its cytotoxicity via in vivo acute toxicity studies using Wistar rats and by cell-based MTT assays. Materials and MethodsThe antiviral properties of the aqueous extract of MAM were investigated against SARS-CoV-2 and chikungunya virus (CHIKV). Further, using ABTS radical scavenging, SOD enzymatic assays and measurement of intracellular ROS, we investigated the antioxidant potential of MAM extract and its ingredients in RAW264.7 cells. Additionally, production of inflammatory mediators was evaluated via NO release, PGE2 production and release of pro-inflammatory cytokines (IL-1β and TNFα). ResultsThe MAM granules and aqueous extracts demonstrated no significant toxicity and demonstrated potent antiviral activity during co-incubation assay with SARS-CoV-2 and CHIKV. Moreover, we observed potent antioxidant and anti-inflammatory activity of MAM extract in a dose dependent manner. Further investigations on the individual ingredients with respect to their antioxidant and anti-inflammatory activities showed that all ingredients contributed synergistically and Withania somnifera showed most potent anti-oxidant activity. ConclusionThe overall in vitro, and in vivo analysis demonstrated that MAM granules were non-toxic and possessed potent antiviral activity. Additionally, observed significant anti-oxidant and anti-inflammatory properties of MAM suggested the modulation of innate immune response in the host validating its use as an effective nutraceutical during viral outbreaks.

Efficient and robust reverse genetics system for bovine rotavirus generation and its application for antiviral screening

Unveiling the molecular mechanisms underlying rotavirus replication and pathogenesis has been hampered by the lack of a reverse genetics (RG) system in the past. Since 2017, multiple plasmid-based RG systems for simian, human, and murine-Like rotaviruses have been established. However, none of the described methods have supported the recovery of bovine rotaviruses (BRVs). Here, we established an optimized plasmid-based RG system for BRV culture-adapted strain (BRV G10P [15] BLR) and clinical isolates (BRV G6P[1] C73, G10P[11] HM26) based on a BHK-T7 cell clone stably expressing T7 polymerase. Furthermore, using this optimized RG system, we successfully rescued the reporter virus BRV rC73/Zs, rHM26/Zs and rBLR/Zs, harboring a genetically modified 1.8-kb segment 7 encoding full-length nonstructural protein 3 (NSP3) fused to ZsGreen, a 232-amino acid green fluorescent protein. Analysis of the stability of genomic insertions showed that the rC73/Zs and rBLR/Zs replicated efficiently and were genetically stable in seven rounds of serial passaging, while rHM26/Zs can be stabilized only up to the third generation, indicating that the BRV segment composition may influence the viral fitness. In addition, we adopted the recombinant reporter viruses for high-throughput screening application and discovered 12 candidates out of 1440 compounds with potential antiviral activities against rotavirus. In summary, this improved RG system of BRVs represents an important tool with great potential for understanding the molecular biology of BRV and facilitates the development of novel therapeutics and vaccines for BRV.

Synthesis and biological activity of some new podophyllotoxin bearing pyrimidine moiety

Podophyllotoxin (PPT), a naturally occurring aryltetralin-type lignan obtained from Podophyllin, an ethanolic extract of Podophyllum peltatum L. (syn. P. hexandnum Royle), exhibits marked biological activity as strong antineoplastic drugs and antiviral agents. Chemical transformations performed on PPT resulted in analogs which also display potent cytotoxic, antiviral, and immunosuppressive activities. In the present research, ten new compounds of PPTs 2a-l bearing pyrimidine moiety were synthesized by the reaction of PPT (1) with 2-methyl sulphonyl pyrimidines in the presence of tetrahydrofuran solvent and base sodium hydride. All the synthesized compounds were tested for antimicrobial activities.. KEYWORDS :4,6-Dimethoxy-2-methylsulfonylpyrimidine, Antimicrobial activity, Podophyllotoxin.

Analytical Characterization, Antioxidant, Antiviral and Antimicrobial Potential of Selected Medicinal Plants

Objectives/background: The infectious consequences of microorganisms are varied due to resistance to existing antimicrobial drugs or new types of microbes causing lethal consequences for humans. Investigation are being performed to control different viral diseases; therefore; medicinal and herbal plants which have a variety of biological properties, can be evaluated for their anti-viral potential. Methods: The antiviral potential of NADES and water extracts of Senna alexandrina ( S. alexandrina), Peganum harmala ( P. harmala) and Citrullus colocynthis ( C. colocynthis) on Nicotiana benthamiana infected with Cotton Leaf Curl Multan virus were investigated. Results: The results of the antiviral assay revealed that both water and NADES extracts of P. harmala could not exhibit antiviral activity. However, water extracts of S. alexandrina and C. colocynthis successfully inhibited the Cotton Leaf Curl Multan virus , allowing the plant to survive compared to their NADES extracts. High-pressure liquid chromatography (HPLC) and Fourier transform infrared spectroscopy (FTIR) analyses showed higher phenolic and flavonoid content in the water extracts of S. alexandrina, C. colocynthis and P. harmala compared to the NADES extracts. Additionally, both water and NADES extracts of P. harmala showed greater antioxidant and antimicrobial activity against S.aureus in comparison to other extracts, while the NADES extract of C. colocynthis demonstrated higher antimicrobial activity against E.coli strains. Conclusions: Therefore, these results demonstrated that Senna Alexandrina and Citrullus Colocynthis exhibited potent antiviral activity, suggesting that these plants could be therapeutic agent for treating viral infections.

Antiviral Activity of Graphene Oxide-Silver Nanocomposites Against Murine Betacoronavirus.

The high infectivity of coronaviruses has led to increased interest in developing new strategies to prevent virus spread. Silver nanoparticles (AgNPs) and graphene oxide (GO) have attracted much attention in the antiviral field. We investigated the potential antiviral activity of GO and AgNPs combined in the nanocomposite GO-Ag against murine betacoronavirus MHV using an in vitro model. GO, AgNPs, and GO-Ag characterization (size distribution, zeta potential, TEM visualization, FT-IR, and EDX analysis) and XTT assay were performed. The antiviral activity of GO-Ag nanocomposites was evaluated by RT-qPCR and TCID50 assays. The results were compared with free AgNPs and pure GO. Cell growth and morphology of MHV-infected hepatocytes treated with GO-Ag composites were analyzed by JuLI™Br. Immunofluorescence was used to visualize the cell receptor used by MHV. Ultrastructural SEM analysis was performed to examine cell morphology after MHV infection and GO-Ag composite treatment. A significant reduction in virus titer was observed for all nanocomposites tested, ranging from 3.2 to 7.3 log10 TCID50. The highest titer reduction was obtained for GO 5 µg/mL - Ag 25 µg/mL in the post-treatment method. These results were confirmed by RT-qPCR analysis. The results indicate that GO-Ag nanocomposites exhibited better antiviral activity compared to AgNPs and GO. Moreover, the attachment of AgNPs to the GO flake platform reduced their cytotoxicity. In addition, the GO-Ag composite modulates the distribution of the Ceacam1 cell receptor and can modulate cell morphology. Graphene oxide sheets act as a stabilizing agent, inhibiting the accumulation of AgNPs and reducing their cellular toxicity. The GO-Ag composite can physically bind and inhibit murine betacoronavirus from entering cells. Furthermore, the constant presence of GO-Ag can inhibit MHV replication and significantly limit its extracellular release. In conclusion, GO-Ag shows promise as an antiviral coating on solid surfaces to minimize virus transmission and spread.

Model informed dose regimen optimizing in development of leritrelvir for the treatment of mild or moderate COVID-19.

Leritrelvir (RAY1216) acts as a main protease inhibitor that hinders the cleavage of viral precursor proteins, thereby inhibiting virus replication of SARS-CoV-2). This antiviral mechanism has shown significant efficacy against the novel coronavirus. Preclinical studies have demonstrated the potent antiviral activity and favorable safety profile of this compound. This study aims to develop a pharmacokinetic model for leritrelvir, with and without ritonavir as a pharmacokinetic enhancer and to evaluate the necessity of co-administration with ritonavir and to investigate different dosage regimens. The model establishment was based on plasma concentration data from a phase I trial involving 72 subjects in single-ascending dose (SAD), multiple-ascending dose (MAD), and a food effect cohort. Analysis was conducted using a nonlinear mixed-effects model, and clinical trial simulations were carried out. The findings of this study demonstrate a favorable safety profile for leritrelvir. With simulation suggests that a 400mg thrice-daily (TID) regimen may be optimal to maintain the trough concentrations (Ctrough) above levels required for inhibiiting viral replication. While ritonavir was found to enhance exposure, it was deemed unnecessary. Gender and food consumption were identified as significant covariates affecting pharmacokinetic parameters, however, no dose adjustments were deemed necessary. This findings supported by subsequent phase II and phase III trials validated the appropriateness of a 400mg TID regimen for the administration of leritrelvir.