Antiviral Compounds Research Articles

Development of an Antiviral Medicinal Plant and Natural Product Database (avMpNp Database) from Biodiversity.

The construction of compound databases (DB) is a strategy for the rational search of bioactive compounds and drugs for new and old diseases. In order to bring greater impact to drug discovery, we propose the development of a DB of bioactive antiviral compounds. Several research groups have presented evidence of the antiviral activity of medicinal plants and compounds isolated from these plants. We believe that compiling these discoveries in a DB would benefit the scientific research community and increase the speed to discover new potential drugs and medicines. Thus, we present the Antiviral Medicinal Plant and Natural Product DB (avMpNp DB) as an important source for acquiring, organizing, and distributing knowledge related to natural products and antiviral drug discovery. The avMpNp DB contains a series of chemically diverse compounds with drug-like profiles. To test the potential of this DB, SARS-CoV-2 Mpro and PLpro enzymatic inhibition assays were performed for available compounds resulting in IC50 values ranging from 6.308±0.296 to 15.795±0.155 μM. As a perspective, artificial intelligence tools will be added to implement computational predictions, as well as other chemical functionalities that allow data validation.

Facile Synthesis of New Antiviral Fluoro-Quinazolines Enabled by Merging Domino Reactions

AbstractQuinazolines, particularly fluoro-quinazolines, represent important structural motifs in bioactive molecules and pharmaceuticals. Despite several known synthetic routes, the efficient synthesis of fluorine-containing quinazolines remains a challenge. Herein, the straightforward and sustainable synthesis of fluorine-substituted quinazolines using domino sequences is reported. The obtained novel fluoro-quinazoline compounds exhibit significant in vitro activity against human cytomegalovirus (HCMV), expanding the library of potential antiviral drug compounds. Our finding outlays the synthetic toolkit for fluoro-quinazolines and introduces new agents for HCMV therapy.

Matrine regulates autophagy in ileal epithelial cells in a porcine circovirus type 2-infected murine model

IntroductionPorcine circovirus type 2 (PCV2) is an important pathogen that causes diarrhea in nursery and fattening pigs, resulting in huge economic losses for commercial pig farms. Protective efficacy of vaccines is compromised by mutations in pathogens. There is an urgent need to articulate the mechanism by which PCV2 destroys the host’s intestinal mucosal barrier and to find effective therapeutic drugs. Increasing attention has been paid to the natural antiviral compounds extracted from traditional Chinese medicines. In the present study, we investigated the role of Matrine in mitigating PCV2-induced intestinal damage and enhancing autophagy as a potential therapeutic strategy in mice.MethodsA total of 40 female, specific-pathogen-free-grade Kunming mice were randomly divided into four groups with 10 mice in each group: control, PCV2 infection, Matrine treatment (40 mg/kg Matrine), and Ribavirin treatment (40 mg/kg Ribavirin). Except for the control group, all mice were injected intraperitoneally with 0.5 mL 105.4 50% tissue culture infectious dose (TCID50)/mL PCV2.ResultsWhile attenuating PCV2-induced downregulation of ZO-1 and occludin and restoring intestinal barrier function in a PCV2 Kunming mouse model, treatment with Matrine (40 mg/kg) attenuated ultrastructural damage and improved intestinal morphology. Mechanistically, Matrine reversed PCV2-induced autophagosome accumulation by inhibiting signal transducer and activator of transcription 3 (STAT3) phosphorylation and upregulating Beclin1 protein expression, thus resisting viral hijacking of enterocyte autophagy.DiscussionOur findings demonstrate that Matrine may be a novel, potential antiviral agent against PCV2 by activating intestine cellular autophagy, which provides a new strategy for host-directed drug discovery.

Combined effect of basic antiherpetic drugs with a new inhibitor of the terminase complex of herpes simplex virus type 1 in Vero cell culture

More than 90% of the world’s population are carriers of herpes simplex virus type 1 (HSV-1). The infection manifests itself in the formation of blisters and ulcers on the face or genitals, and can cause blindness, encephalitis, and generalized infection. All modern first- and second-line antiherpetic drugs selectively inhibit viral DNA-polymerase. The purine-benzoxazine conjugate LAS-131 [(S)-4-[6-(purin-6-yl)aminohexanoyl]-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine], which we described earlier, uses the large subunit of the HSV-1 terminase complex as a biotarget and selectively inhibits its reproduction in vitro. For the first time, we have obtained fundamentally new results on the combined effect of LAS-131 on human herpesvirus infection with practically significant antiviral compounds – nucleoside analogues (acyclovir [ACV], penciclovir [PCV], ganciclovir [GCV], brivudine [BVDU], iododeoxyuridine [IDU], adenine arabinoside [Ara-A], as well as a nucleoside phosphonate analogue (cidofovir [CDV]) and a pirophosphate analogue (foscarnet [FOS]). Using a inhibition assay of cytopathic effect (CPE) induced by a virus, it was shown that when combined with LAS-131, the concentrations of the compounds in combinations providing inhibition of HSV-1-induced CPE by 50%, decreased by 2 times (additive effect, FOS) or more (synergistic effect, ACV, PCV, GCV, IDU, BVDU, Ara-A, CDV). Reducing the concentrations of agents creates non-permissive conditions for the reproduction of HSV-1 and opens up new real possibilities for controlling human herpesvirus infection.

Rising orthotospovirus incidence in India: Challenges and advances in management

Orthotospoviruses (OV) have emerged as a significant agricultural threat in India, posing a severe risk to critical crops, including tomato, chilli, watermelon and groundnut. This review explores the rising incidence of OV, including Groundnut Bud Necrosis Orthotospovirus (GBNV), Watermelon Bud Necrosis Orthotospovirus (WBNV), Capsicum Chlorosis Orthotospovirus (CaCV), Peanut Yellow Spot Orthotospovirus (PYSV), Iris yellow spot Orthotospovirus (IYSV) and Tomato Spotted Wilt Orthotospovirus (TSWV), along with the challenges in their management. These viruses have led to severe yield losses, sometimes causing complete crop failure due to their wide host range and the polyphagous nature of thrips. This further complicates control efforts by facilitating rapid spread across diverse crops and regions. The review highlights the multifaceted challenges in managing OV and thrips, including the lack of durable host resistance, limited diagnostic capabilities, and difficulties in controlling thrips populations. Current management strategies, including cultural practices, chemical control, biological control and resistant genotype development, have shown limited efficacy in providing long-term solutions. Recent advancements in biotechnological approaches, such as RNA interference, are discussed as promising pathways for improved virus management. The review underscores the need for genome editing techniques, such as CRISPR/Cas9, which offer the capacity to develop virus-resistant plants by targeting essential viral or vector genes to disrupt transmission cycles. Additionally, using nanoparticles for targeted delivery of antiviral compounds and novel detection tools presents another innovative solution to effectively mitigate the impact of OV on Indian agriculture.

Both chebulagic acid and punicalagin inhibit respiratory syncytial virus entry via multi-targeting glycoprotein and fusion protein.

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections, with no currently available small-molecule drugs that are both safe and effective. A major obstacle in antiviral drug development is the rapid emergence of drug-resistant viral strains. Targeting multiple viral compounds may help mitigate the development of resistance. Herein, we conducted a drug screening using the Antiviral Traditional Chinese Medicine Active Compound Library, aiming to identify compounds that simultaneously target the RSV fusion (F) protein, glycoprotein (G), and the host heparan sulfate proteoglycans (HSPGs). From this screening, 10 candidate compounds were identified for their ability to interact with all three targets. Among these 10 candidates, chebulagic acid (CHLA) and punicalagin (PUG) demonstrated the most potent inhibition of RSV replication. In vitro dose-response assays confirmed the antiviral efficacy of CHLA (IC50: 0.07864 µM) and PUG (IC50: 0.08065 µM). Further experiments revealed both CHLA and PUG disrupt RSV attachment and membrane fusion by targeting the RSV-F and G proteins, rather than HSPG. Notably, CHLA and PUG were found to bind to the CX3C motif of the RSV-G protein, with docking assays predicting their binding sites at cysteines 176 and 182. Additionally, CHLA enhanced the conformational stability of the RSV-F protein before fusion. In an in vivo study, both CHLA and PUG were shown to alleviate RSV-induced pulmonary pathology by reducing viral titers, mitigating lung injury, and suppressing the inflammatory responses in the lungs. Our findings suggest that CHLA and PUG hold potential as therapeutic agents for RSV infection.IMPORTANCEA significant challenge in developing anti-respiratory syncytial virus (RSV) agents is the rapid emergence of resistant viral strains. Designing drugs that target multiple viral components can effectively reduce the likelihood of developing resistant strains. In this study, we screened compounds from the Antiviral Traditional Chinese Medicine Active Compound Library, aiming to simultaneously targe the RSV fusion (F) protein, glycoprotein (G), and host heparan sulfate proteoglycans (HSPGs). Our findings revealed that chebulagic acid (CHLA) and punicalagin (PUG) significantly inhibited RSV replication both in vitro and in vivo and interacted with all three targets. Both CHLA and PUG were able to disrupt RSV attachment and membrane fusion. Mechanistically, CHLA and PUG were found to bind to the CX3C motif of the RSV-G protein, with CHLA also enhancing the conformational stability of the RSV-F protein before fusion. In conclusion, our study suggests that CHLA and PUG hold promise as therapeutic agents against RSV infection.

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.

Rapid-response RNA-fluorescence in situ hybridization (FISH) assay platform for coronavirus antiviral high-throughput screening

Over the past 25 years, the global community has faced challenges posed by three distinct outbreaks of coronaviruses including severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The identification of a novel alphacoronavirus canine CoV (CCoV-HuPn2018) in human patients in Malaysia underscores the potential for crossover infections to humans. The threat of the ever-evolving nature of viral infections as well as the lingering health and socioeconomic effects of the recent SARS-CoV-2 pandemic emphasize the urgent need for advanced antiviral drug screening tools that can be quickly implemented to strengthen preparedness and preventive measures against future outbreaks. Here, we present the development and validation of a novel RNA-fluorescence in situ hybridization (FISH) imaging assay as a 384-well, high-throughput rapid response platform for antiviral drug discovery. RNA-FISH is a powerful tool to visualize specific mRNA in cultured cells using a high-content imaging platform. The flexibility of RNA-FISH probe sets allows for the rapid design of viral genome-specific probes, enabling in vitro assay development to test for inhibition of viral replication by either biologic or small molecule inhibitors. Screening of 170 antiviral compounds in concentration-response demonstrates a strong correlation between the RNA-FISH assay and an immunofluorescence assay (IFA) for both human coronaviruses HCoV-OC43 and HCoV-229E. Additionally, we successfully applied this methodology in the context of CCoV strain 1–71, proving rapid development and deployment, opening new avenues for the evaluation of antiviral drugs to potential future emerging threats.

Expression of Toll-like Receptor Genes and Antiviral Cytokines in Macrophage-like Cells in Response to Indole-3-carboxylic Acid Derivative

Ongoing outbreaks and often rapid spread of infections caused by coronaviruses, influenza, Nipah, Dengue, Marburg, monkeypox, and other viruses are a concern for health authorities in most countries. Therefore, the search for and study of new antiviral compounds are in great demand today. Since almost all viruses with pandemic potential have immunotoxic properties of various origins, particular attention is paid to the search and development of immunomodulatory drugs. We have synthesised a new compound related to indole-3-carboxylic acid derivatives (hereinafter referred to as the XXV) that has antiviral and interferon-inducing activity. The purpose of this work is to study the effect of the XXV on the stimulation of the expression of toll-like receptor genes, interferons, and immunoregulatory cytokines in a macrophage-like cell model. In this study, real-time PCR methods were used to obtain data on the transcriptional activity of genes in macrophage-like cells. Stimulation of the genes of toll-like receptors TLR2, TLR3, TLR4, TLR7, TLR8, and TLR9 was detected. A high-fold increase in stimulation (from 6.5 to 16,000) of the expression of the TLR3 and TLR4 genes was detected after 4 h of exposure to the XXV. Increased activity of interferon (IFNA1, IFNA2, IFNB1, IFNK, and IFNλ1) genes with simultaneous stimulation of the expression of interferon receptor (IFNAR1 and IFNAR2) genes and signalling molecule (JAK1 and ISG15) genes was detected. Increased fold stimulation of the expression of the cytokine genes IL6, TNFA, IL12A, and IL12B was also observed. Thus, it is shown that the XXV is an activator of TLR genes of innate immunity, which trigger signalling mechanisms of pathogen “recognition” and lead to stimulation of the expression of genes of proinflammatory cytokines and interferons.

Computational Screening of Natural Compounds as Antiviral Candidates Targeting the SARS-CoV-2 Main Protease

The onset of the global pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Wuhan in December 2019 has led to an urgent need for effective preventive and therapeutic solutions. Among the various approaches explored, natural products have shown potential in the fight against COVID-19. This study employed computational techniques to screen and evaluate six natural antiviral compounds for their effectiveness against the SARS-CoV-2 Main Protease (Mpro). By using molecular docking simulations, the interactions between these natural compounds and the target proteins were predicted and analyzed, focusing on factors such as binding affinity, interaction patterns, and structural compatibility within the active sites. The analysis indicated that Cladosin C and Rhodatin formed the most stable interactions with Mpro, engaging with several critical residues. Cannabidiol, Capsaicin, and Kappa-Carrageenan also demonstrated promising interactions, though with some variability. On the other hand, Astaxanthin exhibited the least stable binding, suggesting limited antiviral potential. This research provides insights into the possible roles of these natural compounds as antagonists of the SARS-CoV-2 Mpro enzyme. Further in vitro and in vivo studies are necessary to confirm the antiviral properties of these compounds, and future research should investigate their broader antiviral applications.

Amaryllidaceae Alkaloids Screen Unveils Potent Anticoronaviral Compounds and Associated Structural Determinants.

Betacoronaviruses encompass a spectrum of respiratory diseases, from common cold caused by the human coronavirus (HCoV)-OC43 to life-threatening severe acute respiratory syndrome (SARS)-CoV-2. Addressing the constant need for novel antiviral compounds, we turned to the exploration of 40 plant-specialized metabolites produced by the medicinal plant family Amaryllidaceae, known to produce lycorine, a strong antiviral alkaloid. The present screen included 35 alkaloids with representatives of 8 ring-type structures. Pancracine, crinamine, hemanthamine, and hemanthidine exhibited potency comparable to lycorine in blocking HCoV-OC43 replication, while amarbellisine demonstrated superior efficacy (SI = 60, EC50 = 0.2 μM). Their anticoronaviral activity was confirmed using a SARS-CoV-2 replicon system. Time-of-drug-addition experiments established that a postentry step consistent with ribonucleic acid (RNA) replication or translation was targeted. Most antiviral Amaryllidaceae alkaloids selectively induced the expression of transcripts associated with the integrated stress response. Structure-activity relationship analyses elucidated key functional groups contributing to antiviral properties in the crinine- and lycorine-type. This study reveals that Amaryllidaceae produce a diverse repertoire of promising antiviral compounds in addition to lycorine, offering insights for developing new antiviral agents.

Cannabinoid-Inspired Inhibitors of the SARS-CoV-2 Coronavirus 2'-O-Methyltransferase (2'-O-MTase) Non-Structural Protein (Nsp10-16).

The design and synthesis of antiviral compounds were guided by computationally predicted data against highly conserved non-structural proteins (Nsps) of the SARS-CoV-2 coronavirus. Chromenephenylmethanone-1 (CPM-1), a novel biphenylpyran (BPP), was selected from a unique natural product library based on in silico docking scores to coronavirus Nsps with high specificity to the methyltransferase protein (2'-O-MTase, Nsp10-16), which is responsible for viral mRNA maturation and host innate immune response evasion. To target the 2'-O-MTase, CPM-1, along with intermediate BPP regioisomers, tetrahydrophenylmethanones (TPMs), were synthesized and structurally validated via nuclear magnetic resonance (NMR) data and DP4+ structure probability analyses. To investigate the activity of these BPPs, the following in vitro assays were conducted: SARS-CoV-2 inhibition, biochemical target validation, mutagenicity, and cytotoxicity. CPM-1 possessed notable activity against SARS-CoV-2 with 98.9% inhibition at 10 µM and an EC50 of 7.65 µM, as well as inhibition of SARS-CoV-2's 2'-O-MTase (expressed and purified) with an IC50 of 1.5 ± 0.2 µM. In addition, CPM-1 revealed no cytotoxicity (CC50 of >100 µM) or mutagenicity (no frameshift or base-pair mutations). This study demonstrates the potential of computational modeling for the discovery of natural product prototypes followed by the design and synthesis of drug leads to inhibit the SARS-CoV-2 2'-O-MTase.

Structural and free energy landscape analysis for the discovery of antiviral compounds targeting the cap-binding domain of influenza polymerase PB2

Influenza poses a significant threat to global health, with the ability to cause severe epidemics and pandemics. The polymerase basic protein 2 (PB2) of the influenza virus plays a crucial role in the viral replication process, making the CAP-binding domain of PB2 an attractive target for antiviral drug development. This study aimed to identify and evaluate potential inhibitors of the influenza polymerase PB2 CAP-binding domain using computational drug discovery methods. We employed a comprehensive computational approach involving virtual screening, molecular docking, and 500 ns molecular dynamics (MD) simulations. Compounds were selected from the Diverse lib database and assessed for their binding affinity and stability in interaction with the PB2 CAP-binding domain. The study utilized the generalized amber force field (GAFF) for MD simulations to further evaluate the dynamic behaviour and stability of the interactions. Among the screened compounds, compounds 1, 3, and 4 showed promising binding affinities. Compound 4 demonstrated the highest binding stability and the most favourable free energy profile, indicating strong and consistent interaction with the target domain. Compound 3 displayed moderate stability with dynamic conformational changes, while Compound 1 maintained robust interactions throughout the simulations. Comparative analyses of these compounds against a control compound highlighted their potential efficacy. Compound 4 emerged as the most promising inhibitor, with substantial stability and strong binding affinity to the PB2 CAP-binding domain. These findings suggest that compound 4, along with compounds 1 and 3, holds the potential for further development into effective antiviral agents against influenza. Future studies should focus on experimental validation of these compounds and exploration of resistance mechanisms to enhance their therapeutic utility.

The effective multiplicity of infection for HCMV depends on activity of the cellular 20S proteasome.

HCMV infection and reactivation continues to contribute to morbidity and mortality around the world. Antiviral compounds are available but have limitations. Here, we have defined the impact of the proteasome inhibitor bortezomib on HCMV replication. Proteasomal activities play a critical role in temporal changes required for replication. We demonstrate that disrupting these activities inhibits viral replication while likely supporting increased antiviral activity of the anti-HCMV agent, maribavir. Using a combination of live cell imaging and computational tools, we discover that a subset of infected cells progresses to fulminant infection which we define as the effective MOI, and this subset would otherwise be missed when analyzing the average of the population.

Antiviral Potential of Chiococca alba (L.) Hitchc. Plant Extracts Against Chikungunya and Mayaro Viruses.

Chikungunya and Mayaro fevers are viral infectious diseases characterized by fever and arthralgia, for which there are currently no effective vaccines or treatments. The urgent need for novel antiviral agents against Chikungunya virus (CHIKV) and Mayaro virus (MAYV) has led to interest in plant-based compounds that can disrupt the viral replication cycle. Chiococca alba (L.) Hitchc., a Neotropical plant traditionally used by Yucatec Maya healers as an antipyretic and antirheumatic, may hold potential as a source of antiviral agents. This study aimed to evaluate the antiviral potential of C. alba methanolic extracts (CAH21 and CAH24) against CHIKV and MAYV through preliminary in vitro and in silico analyses. The cytotoxicity of two methanolic extracts from C. alba roots was assessed in Vero cells using the neutral red assay, and their viral activity was determined via plaque assay post-treatment. Given the observed antiviral effects, we used computational predictions to explore interactions between the multifunctional nsP2 proteases and secondary metabolites identified in C. alba extracts. The metabolites were identified using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). Phytochemical analysis revealed the presence of flavonoids, coumarins, and phenolic acids in the C. alba extracts. In vitro assays demonstrated that both extracts inhibited over 70% of activity against CHIKV and MAYV at a concentration of 60 µg/mL. In silico predictions suggested that the flavonoids naringin and vitexin had the highest affinity for the nsP2 proteases of CHIKV and MAYV, indicating their potential as viral inhibitors. Our findings revealed that C. alba extract represents a promising source of novel antiviral compounds.

In Silico evaluation of the anti-influenza potential of Streptomyces bioactive compounds

Influenza, a highly contagious respiratory viral disease characterized by its short incubation period and severe symptoms, is treatable with antiviral drugs targeting viremia. Among new antiviral agents, Actinobacteria, particularly from the Streptomyces genus, are notable for their ability to produce potent antiviral compounds. This study evaluates the antiviral potential of Streptomyces sp. KSF 103, isolated from Kuala Sat, Jerantut, Pahang, against the Influenza A virus (IAV). Using molecular docking tools such as AutoDock Vina and PyMOL, the interactions of four compounds – hypoxanthine, vitamin D, purine, and aminocaproic acid – were analyzed against IAV proteins. Vitamin D exhibited the highest binding affinity against H3N2’s M2 (−9.6 kcal/mol) and HA (−9.2 kcal/mol) proteins. Additionally, RMSD dynamics parameters indicated that the best-scoring complexes are predicted to be satisfactorily stable under physiological settings. These findings suggest that Streptomyces sp. KSF 103 could be a promising source for developing new antiviral treatments against influenza.

Design, In Silico, and In vitro Evaluation of Polymer-Based Drug Conjugates Incorporated with Derivative of Cinnamic Acid, Zidovudine, and 4-Aminosalicylic Acid against Pseudo-HIV-1.

The incorporation of anti-HIV drugs into polymer to form polymer-drug conjugates has been reported to result in improved therapeutic activity. Zidovudine, an anti-HIV drug, was explored alone and in combination with known drug molecules using polyamidoaminebased carriers. Polymer-drug conjugates incorporated with zidovudine, cinnamic acid, and 4-aminosalicylic acid were prepared and evaluated for their potential efficacy in vitro against pseudo- HIV-1. Aqueous Michael addition polymerization reaction was employed to prepare the conjugates. The conjugates were incorporated with zidovudine, cinnamic acid, and 4-aminosalicylic acid. They were characterized by SEM/EDX, XRD, FTIR, NMR, LC-MS, particle size analysis, in vitro analysis, computational studies, and in silico toxicity predictions. The conjugates displayed spherically shaped morphology. The in vitro findings showed that polymer-drug conjugates, T15 and T16, with a single drug were effective against pseudo- HIV-1 at high concentrations of 111.11 and 333.33 μg/mL, respectively. The molecular docking studies confirmed the in vitro results. The Swiss ADME, ProTox-II, and GUSAR (General Unrestricted Structure-Activity Relationships) revealed that these compounds are promising antiviral compounds. The prepared polymer-drug conjugates with a single drug showed promising effects against the Pseudo-HIV-1, and the conjugates displayed features that make them potential anti- HIV therapeutics that require further studies.

Evaluation of the antiviral activity of different extracts of Gliricidia sepium and Xylopia aethiopica on enteroviruses isolated in Côte d'Ivoire

Objective : The emergence of viral infections has highlighted the need for new antiviral molecules. This study is part of an exploration into finding new antiviral compounds from medicinal plants used in traditional pharmacopoeia in Côte d'Ivoire. The aim is to determine which of the extracts from Gliricidia sepium leaves and Xylopia aethiopica fruits (hydroalcoholic, hexane/water, ethyl acetate/water, aqueous) exhibits the best antiviral activity. Methodology: The cytotoxicity of each partition P1 (hydroalcoholic), P2 (hexane/water), P3 (ethyl acetate/water), P4 (aqueous) of Gliricidia sepium leaves and P1' (hydroalcoholic), P2' (hexane/water), P3' (ethyl acetate/water), P4' (aqueous) of Xylopia aethiopica fruits is determined on RD cells. The antiviral activity of these partitions was then evaluated against a type 1 enterovirus. Results: The hexane-water partition showed high antiviral activity against type 1 enterovirus, with an inhibition of 65.78±9.21% at a concentration of 1 μg/mL for Gliricidia sepium leaves, compared to a non-significant inhibition of 86.84±5.26% at 31.25 μg/mL for Xylopia aethiopica fruits. Additionally, the aqueous partition of Gliricidia sepium induced an inhibition of 50±0.01% at a concentration of 1.95 μg/mL. Conclusion: Hexane-water and aqueous partitions of Gliricidia sepium showed́ potent antiviral activitý against enterovirus 1 than those of Xylopia. aethiopica. Keywords: plant partition, RD cells, enterovirus type 1.

Oxoammonium salts exert antiviral effects against coronavirus via denaturation of their spike proteins

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV2) infection has forced social changes worldwide. Development of potent antiviral agents is necessary to prevent future pandemics. Titanium oxide, a photocatalyst, is a long-acting antiviral agent; however, its effects are weakened in the dark. Therefore, new antiviral substances that can be used in the dark are needed. Two types of nitroxyl radicals, 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) and 2-azaadamantane N-oxyl (AZADO), are commonly used as oxidation catalysts utilizing oxygen in the air as the terminal oxidant. Therefore, in this study, we aimed to evaluate the potential of these radicals as antiviral compounds with sustained activity even in the dark. We evaluated the antiviral effects of oxoammonium salts corresponding to TEMPO and AZADO (TEMPO-Oxo and AZADO-Oxo, respectively), which are the active forms of nitroxyl radicals in oxidation reactions. TEMPO-Oxo and AZADO-Oxo inhibited the binding of SARS-CoV2 spike protein receptor-binding domain (S-RBD) to angiotensin-converting enzyme 2. Notably, AZADO-Oxo exhibited a 10-fold stronger inhibitory effect than TEMPO-Oxo. TEMPO-Oxo and AZADO-Oxo also denatured S-RBD; however, effects of AZADO-Oxo were 10-fold stronger than those of TEMPO-Oxo and did not change in the dark. Some S-RBD peptides treated with AZADO-Oxo were cleaved at the N-terminal side of tyrosine residues. TEMPO-Oxo and AZADO-Oxo exhibited concentration-dependent antiviral effects against feline coronavirus. In conclusion, active forms of the nitroxyl radicals, TEMPO-Oxo and AZADO-Oxo, exerted antiviral effects by denaturing S-RBD, regardless of the presence or absence of light, suggesting their potential as novel antiviral agents.

A critical review on the active anti-viral metabolites of bioprospecting traditionally used plant species from semi-arid regions of the subcontinent.

Plants are crucial medicinal resources, with 80 % of people relying on them for primary healthcare. The search for natural antiviral compounds is increasing, especially in semi-arid ecosystems where abiotic stress promotes the production of beneficial secondary metabolites. This review highlights semi-arid plants with the potential as functional foods to combat viral diseases and other illnesses. Literature was searched in databases like ScienceDirect to gather information on novel compounds from stress-tolerant semi-arid plant species. These compounds have potential uses in treating viral infections and other health issues such as diabetes and high blood pressure. The review screened 61 semi-arid plants known for their antiviral metabolites. Eight plants were identified with novel antiviral compounds. Key metabolites include agathisflavone, pectic arabinogalactan, azadirachtin, aloin, aloe-emodin, aloesaponarin I, allicin, terpenoids, chlorogenic acids, curcumin, chromones, β-sitosterol, lupeol, oleuropein, carissol, β-amyrin, and ∆-9-tetrahydrocannabinol. Stress-tolerant semi-arid plants are significant sources of metabolites for treating infectious diseases and boosting immune systems. Further research on these metabolites in animal models is needed to verify their efficacy for treating human diseases during endemic and pandemic outbreaks, such as COVID-19.