Antiviral Activity Research Articles

Flunarizine as a Candidate for Drug Repurposing Against Human Pathogenic Mammarenaviruses.

Lassa fever (LF), a viral hemorrhagic fever disease with a case fatality rate that can be over 20% among hospitalized LF patients, is endemic to many West African countries. Currently, no vaccines or therapies are specifically licensed to prevent or treat LF, hence the significance of developing therapeutics against the mammarenavirus Lassa virus (LASV), the causative agent of LF. We used in silico docking approaches to investigate the binding affinities of 2015 existing drugs to LASV proteins known to play critical roles in the formation and activity of the virus ribonucleoprotein complex (vRNP) responsible for directing replication and transcription of the viral genome. Validation of docking protocols were achieved with reference inhibitors of the respective targets. Our in silico docking screen identified five drugs (dexamethasone, tadalafil, mefloquine, ergocalciferol, and flunarizine) with strong predicted binding affinity to LASV proteins involved in the formation of the vRNP. We used cell-based functional assays to evaluate the antiviral activity of the five selected drugs. We found that flunarizine, a calcium-entry blocker, inhibited the vRNP activity of LASV and LCMV and virus surface glycoprotein fusion activity required for mammarenavirus cell entry. Consistently with these findings, flunarizine significantly reduced peak titers of LCMV in a multi-step growth kinetics assay in human A549 cells. Flunarizine is being used in several countries worldwide to treat vertigo and migraine, supporting the interest in exploring its repurposing as a candidate drug to treat LASV infections.

Structure-Based Optimization of Pyridone α-Ketoamides as Inhibitors of the SARS-CoV-2 Main Protease.

The main protease Mpro is a clinically validated target to treat infections by the coronavirus SARS-CoV-2. Among the first reported Mpro inhibitors was the peptidomimetic α-ketoamide 13b, whose cocrystal structure with Mpro paved the way for multiple lead-finding studies. We established structure-activity relationships for the 13b series by modifying residues at the P1', P3, and P4 sites. Guided by cocrystal structures, we reduced the P1' substituent size to better fill the pocket and added a fluorine substituent to the pyridone ring, enabling a new hydrogen bond with Gln189 in P3. Among 22 novel analogues, 6d and 12d inhibited Mpro with IC50s of 110 nM and 40 nM, improving the potency of 13b by up to 9.5-fold. Compound 6d had pronounced antiviral activity with an EC50 of 1.6 μM and was stable in plasma and microsomes. The study illustrates the potential of structure-based design to systematically improve peptidomimetic α-ketoamides.

Design, Synthesis, and Unprecedented Interactions of Covalent Dipeptide-Based Inhibitors of SARS-CoV-2 Main Protease and Its Variants Displaying Potent Antiviral Activity.

The main protease (Mpro) of SARS-CoV-2 is a key drug target for the development of antiviral therapeutics. Here, we designed and synthesized a series of small-molecule peptidomimetics with various cysteine-reactive electrophiles. Several compounds were identified as potent SARS-CoV-2 Mpro inhibitors, including compounds 8n (IC50 = 0.0752 μM), 8p (IC50 = 0.0887 μM), 8r (IC50 = 0.0199 μM), 10a (IC50 = 0.0376 μM), 10c (IC50 = 0.0177 μM), and 10f (IC50 = 0.0130 μM). Most of them additionally inhibited cathepsin L and were also active against SARS-CoV-1 and MERS-CoV Mpro. In Calu-3 cells, several inhibitors, including 8r, 10a, and 10c, displayed high antiviral activity in the nanomolar range without showing cellular toxicity. The cocrystal structure of SARS-CoV-2 Mpro in complex with 8p revealed covalent binding to the enzyme's catalytic residue Cys145 and showed specific, unprecedented interactions within the substrate binding pocket. Compounds 10c and especially 8n were effective against a panel of naturally occurring nirmatrelvir-resistant mutants, particularly E166V, and showed metabolic stability and additional favorable pharmacokinetic properties, making it a suitable candidate for further preclinical development.

Exploring the pharmacological potential of Macrobrachium acanthurus hemocyanin: preliminary biological activity studies

Hemocyanin (Hc) is a copper-containing hemoprotein found in the hemolymph of invertebrates such as mollusks and arthropods. It plays essential roles in oxygen transport, immune defense, and molting processes. Due to their antiviral, antimicrobial, and phenoloxidase (PO) activities, Hcs hold significant potential in biotechnology. This study aims to obtain the Hc from the shrimp Macrobrachium acanthurus and perform preliminary biological activity tests (PO and antimicrobial activity) of this Hc. The results will serve as a basis for future structural and biological investigations of this unique protein. HcMac was purified using ultracentrifugation and size exclusion liquid chromatography (SEC). PO activity was induced by the surfactant SDS in the presence of dopamine hydrochloride, monitored by optical absorption at 475 nm using a spectrophotometer. Tests were performed to evaluate the inhibitory activity against Candida neoformans, Candida albicans and some fish pathogens. The results demonstrated that the surfactant SDS induced PO activity, with optimal formation observed at an SDS concentration of 1.0 mmol L-1. However, HcMac did not exhibit antimicrobial activity in the tests performed. Despite this, we cannot rule out the hypothesis that this Hc has biological activity and an immunological role, since it showed PO activity.

Lipid-encapsulated gold nanoparticles: an advanced strategy for attenuating the inflammatory response in SARS-CoV-2 infection

BackgroundNanodrugs play a crucial role in biomedical applications by enhancing drug delivery. To address safety and toxicity concerns associated with nanoparticles, lipid-nanocarrier-based drug delivery systems have emerged as a promising approach for developing next-generation smart nanomedicines. Ginseng has traditionally been used for various therapeutic purposes, including antiviral activity. This study aimed to prepare a biocompatible and therapeutically potent Korean ginseng nanoemulsion (KGS-NE) using ginseng seed oil (GSO), optimize its encapsulation and drug delivery efficiency, and evaluate its antiviral activity.ResultsVarious techniques were utilized to confirm the KGS-NE formation. Energy-dispersive X-ray spectroscopy identified gold nanoparticles with the highest Au peak at 2.1 keV. Selected area diffraction patterns revealed crystallographic structures. FT-IR spectrometry detected functional groups, with peaks at 2922.09 cm−1 (alkene C–H stretching), 1740.24 cm−1 (aldehyde C=O stretching), and 1098.07 cm−1 (C–O stretching in secondary alcohol). Storage stability studies showed that KGS-NE maintained its size and stability for 6 months at 4 °C. The KGS-NE exhibited a dose-dependent suppression of HCoV-OC43 viral replication in Vero E6 cells. RNA sequencing analysis unveiled differentially expressed genes (DEGs) specifically involved in the ABC transporters signaling pathway. KGS-NE oral administration facilitated the recovery of mice induced with the receptor binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein, as confirmed by inflammatory markers expression in lung tissue. In the Syrian hamster infected with the SARS-CoV-2 model, the lungs dissected showed enlarged morphology and induced inflammatory cytokines. This effect was mitigated with KGS-NE oral administration, as observed through H&E and qRT-PCR analysis. Biochemical analysis at various oral administration concentrations demonstrated that KGS-NE had no adverse effects on the kidney and liver.ConclusionsOur findings strongly suggest that oral administering KGS-NE in mice and Syrian hamster models has the potential to effectively mitigate lung inflammation against coronavirus. This indicates a promising new strategy for developing the antiviral nano-agent against SARS-CoV-2.Graphical

Intranasally administrated fusion-inhibitory lipopeptides block SARS-CoV-2 infection in mice and enable long-term protective immunity

We have assessed antiviral activity and induction of protective immunity of fusion-inhibitory lipopeptides derived from the C-terminal heptad-repeat domain of SARS-CoV-2 spike glycoprotein in transgenic mice expressing human ACE2 (K18-hACE2). The lipopeptides block SARS-CoV-2 infection in cell lines and lung-derived organotypic cultures. Intranasal administration in mice allows the maintenance of homeostatic transcriptomic immune profile in lungs, prevents body-weight loss, decreases viral load and shedding, and protects mice from death caused by SARS-CoV-2 variants. Prolonged administration of high-dose lipopeptides has neither adverse effects nor impairs peptide efficacy in subsequent SARS-CoV-2 challenges. The peptide-protected mice develop cross-reactive neutralizing antibodies against both SARS-CoV-2 used for the initial infection and recently circulating variants, and are completely protected from a second lethal infection, suggesting that they developed SARS-CoV-2-specific immunity. This strategy provides an additional antiviral approach in the global effort against COVID-19 and may contribute to development of rapid responses against emerging pathogenic viruses.

Green Synthesis of Tetrahydropyrazino[2,1-a:5,4-a']diisoquinolines as SARS-CoV-2 Entry Inhibitors.

A class of tetrahydropyrazino[2,1-a:5,4-a']diisoquinoline derivatives were synthesized under environmentally friendly conditions using water as the solvent. The 3-D structures of some synthesized compounds were determined by X-ray diffraction. Since naturally occurring isoquinoline alkaloids have significant antiviral activities against a wide range of viruses, including coronaviruses, the synthesized compounds were assayed for their inhibitory activities against SARS-CoV-2. Our results showed that the active compounds 50 and 96 blocked the delta SARS-CoV-2 entry into VeroE6 cells to display EC50 of 26.5 ± 6.9 and 17.0 ± 3.7 μM, respectively, by inhibiting the interaction between SARS-CoV-2 Spike's receptor binding domain (RBD) and human receptor angiotensin-converting enzyme 2 (ACE2), and CC50 greater than 100 μM. This study provides a green synthesis method of tetrahydropyrazinodiisoquinoline for antiviral or other applications.

Selective suppression of influenza A/H5N1 virus replication <i>in vitro</i> using nanocomplexes consisting of siRNA and aminopropylsilanol nanoparticles

Relevance. Studies on model systems have confirmed the effectiveness of antisense oligonucleotides, including those that contain photoactive groups, for the modification of nucleic acids. However, this strategy has not yet found wide application due to the lack of successful methods for the intracellular delivery. The development of effective preparations capable of acting on target nucleic acids in cells is an urgent task. The aim of the study is to create nanocomplexes consisting of aminopropylsilanol nanoparticles and short interfering RNA (siRNA) to study their effect on target nucleic acids by the example of inhibition of influenza A virus replication in vitro. Materials and methods. MDCK cells, influenza virus A/chicken/Kurgan/05/2005 (A/H5N1), aminopropylsilanol nanoparticles, and native and modified siRNA molecules. Results and discussion. We have prepared unique Si~NH2/siRNA nanocomplexes, which consist of aminopropylsilanol nanoparticles and siRNA molecules, which enable cell penetration and selective interaction with target nucleic acids, respectively. The antiviral activity of the proposed nanocomplexes has been studied on MDCK cells infected with the influenza A/H5N1 virus. It has been shown that the double-stranded siRNA molecules in the nanocomplexes, which act by the RNA interference mechanism, are more efficient in inhibiting the replication of the influenza virus than the corresponding single-stranded RNA fragments. The most effective nanocomplex that contained siRNA targeted at the chosen region of mRNA segment 5 of the viral genome reduced virus replication in the culture by a factor of 630. We have shown that non-agglomerated and water-soluble aminopropylsilanol nanoparticles are low-toxic, capable of delivering siRNA into cells and protecting siRNA in the Si~NH2/siRNA nanocomplexes from hydrolysis by cellular nucleases. Conclusion. The biological activity of the created nanocomplexes has been demonstrated by the example of highly effective selective suppression of influenza A/chicken/Kurgan/05/2005 virus replication in the cellular system.

Iron improves the antiviral activity of NK cells

Natural killer (NK) cells are innate immune cells that play a crucial role as a first line of defense against viral infections and tumor development. Iron is an essential nutrient for immune cells, but it can also pose biochemical risks such as the production of reactive oxygen species. The importance of iron for the NK cell function has gained increasing recognition. We have previously shown that NK cells require iron to efficiently eliminate virus-infected target cells; however, the impact of nutritional iron deficiency on NK cell function and the therapeutic benefits of iron supplementation remain unclear. Here, we demonstrate that diet-related low iron levels lead to increased retroviral loads due to functional NK cell impairment, while iron supplementation enhances NK cell proliferation, as well as their cytotoxic efficacy. Notably, iron-treated NK cells exhibited significant metabolic changes, including mitochondrial reorganization. Interestingly, although iron supplementation decreased the NK cell’s cytokine production, it significantly improved NK cell degranulation and the expression of cytotoxicity-associated proteins. These findings highlight the critical role of iron in maintaining NK cell immunity and suggest that iron supplementation may hold therapeutic potential for supporting the treatment of viral infections and immunodeficiency disorders.

Silver Nanoparticles-Functionalized Textile against SARS-CoV-2: Antiviral Activity of the Capping Oleylamine Molecule.

COVID-19 disease, triggered by SARS-CoV-2 virus infection, has led to more than 7.0 million deaths worldwide, with a significant fraction of recovered infected people reporting postviral symptoms. Smart surfaces functionalized with nanoparticles are a powerful tool to inactivate the virus and prevent the further spreading of the disease. Literature reports usually focus on the role of nanomaterial composition and size dispersion in evaluating their efficacy against SARS-CoV-2. Here, the anti-SARS-CoV-2 activity of oleylamine (OAm) used as a capping agent of silver nanoparticles is quantified for the first time. Spherical hydrophobic nanoparticles with 8 ± 2 nm diameter were prepared and characterized by Fourier transform infrared, dynamic light scattering, and transmission electron microscopy techniques. Biological assays showed that microgram amounts of nanoparticles, deposited on nonwoven textile obtained from surgical masks, efficiently inactivated up to 99.6(2)% of the virus with just 2 min of exposure. The virucidal activity of the corresponding amount of free OAm has been determined as well, reaching up to 67(1)% of activity for an exposure time of 10 min. Inductively coupled plasma optical emission spectrometry results pointed out a low leaching out of the nanoparticles in contact with water or culture medium. All in all, these results propose the capping molecules as an important chemical variable to be taken into account in the design of fast, efficient, and long-lasting anti-SARS-CoV-2 coatings.

HSPG-binding peptide Pep19-2.5 is a potent inhibitor of HPV16 infection.

Peptide-based therapeutics are gaining attention for their potential to target various viral and host cell factors. One notable example is Pep19-2.5 (Aspidasept), a synthetic anti-lipopolysaccharide peptide that binds to heparan sulfate proteoglycans (HSPGs) and has demonstrated inhibitory effects against certain bacteria and enveloped viruses. This study explores, for the first time, the effectiveness of Pep19-2.5 against a non-enveloped virus, using pseudoviruses of the oncogenic human papillomavirus type 16 (HPV16) as a model. HPV16 infects epithelial cells of the skin and mucosa by using multiple cell surface receptors with initial attachment to HSPGs. Pharmacological inhibition with Pep19-2.5 in HeLa and HaCaT cells resulted in a concentration-dependent reduction of HPV16 PsV infection, with near-complete blockade observed at higher concentrations. The half-maximal inhibitory concentration (IC50) was determined to be 116 nM in HeLa cells and 183 nM in HaCaT cells, highlighting its potent antiviral activity. Our results demonstrate that Pep19-2.5 not only inhibits HPV16 PsV binding to the cell surface but also significantly reduces infection when administered post-binding. Imaging analyses revealed Pep19-2.5-dependent release of large cell-associated crowds of viral particles, suggesting interference with the transfer to secondary receptor molecules. This was corroborated by the effectiveness of Pep19-2.5 in an HSPG-negative cell line, indicating that the peptide disrupts virus binding to both primary and secondary interaction partners. Based on these findings, we propose that the antimicrobial effect of Pep19-2.5 is not limited to HSPG-dependent infections. Additionally, Pep19-2.5 may be a valuable tool for dissecting specific steps in the viral entry process.

Characteristics of the monkeypox virus isolate obtained from the first patient in Russia and its sensitivity to 7-[N-(4-trifluoromethylbenzoyl)-hydrazinocarbonyl]-tricyclo-[3.2.2.0^2,4]non-8-en-6-carboxylic acid

Introduction. Since early May 2022, more than 90,000 cases of monkeypox virus infection have been reported in more than 70 countries around the World. This is the largest outbreak of monkeypox ever recorded outside of Africa. The aim of the study is to confirm the first case of monkeypox in Russia, to isolate and sequence a new strain of monkeypox virus (MPXV), and to assess its sensitivity to the 7-[N-(4-trifluoromethylbenzoyl)-hydrazinocarbonyl]-tricyclo-[3.2.2.0^2,4]non-8-en-6-carboxylic acid (NIOCH-14) antipox drug. Materials and methods. The biological materials obtained from the affected area of the skin (contents of vesicles), a nasopharyngeal smear, sputum and venous blood from a patient with suspected monkeypox were used. The disease was confirmed by PCR followed by determination of the nucleotide sequence of viral DNA by sequencing. Isolation of the new MPXV strain from clinical samples was carried out in Vero E6 cells. The antiviral effectiveness of NIOCH-14 against the new MPXV strain was assessed using an adapted spectrophotometric method. Results. A diagnostic study of the biological samples of a patient who returned from a tourist trip to European countries with complaints of skin rashes all over the body revealed MPXV DNA. A new strain of MPXV was isolated from vesicles in Vero E6 cells, and the genomic sequence MPXV-pustule S45 was assembled using high-throughput parallel sequencing (NGS). Discussion. The effectiveness of the finished dosage form of NIOCH-14 against the new strain of MPXV based on the results of determining the 50% virus inhibitory concentration (IC50) was 0.02 μg/mL, and the selectivity index (SI) was 15,000. Conclusion. In this study, the pathogen of monkeypox was detected and identified using real-time PCR, NGS and electron microscopy, and the first imported case of this disease in Russia was confirmed. It has been proven that the drug NIOCH-14 exhibits high antiviral activity in vitro against the new MPXV strain.

Deciphering the nature and statistical optimization of antimicrobial metabolites of two endophytic bacilli

In this study, Allium sativum, garlic, was selected to isolate endophytic bacteria and to evaluate the antimicrobial, antiviral, antioxidant, and cytotoxic activities of their produced metabolites followed by identification of the biosynthetic gene cluster of the antimicrobial metabolites using Oxford Nanopore Technology (ONT). Two bacterial isolates, C6 and C11, were found to have a broad-spectrum antagonistic effect against four standard microbial strains and were molecularly identified using 16 S ribosomal RNA sequence analysis and deposited in a local culture collection as B. velezensis CCASU-C6, and B. subtilis CCASU-C11, respectively. Optimization for the maximum production of antimicrobial metabolites revealed that a four-day incubation period was optimal, with sucrose and tryptone serving as the best carbon and nitrogen sources for the fermentation media. Response surface methodology model using the central composite design was created resulting in a 1.2-fold and 1.8-fold improvement in antimicrobial metabolite(s) production of C6 and C11 isolates, respectively. The optimal production conditions were found to be a temperature of 33 °C, pH of 7, and an agitation rate of 200 rpm for C6 metabolite, and a temperature of 37 °C, pH of 7, and an agitation rate of 250 rpm for C11 metabolite. Both bacterial isolates displayed antioxidant and antiviral activity and mild cytotoxic action. Genomic sequence and antiSMASH analysis showed that the biosynthetic gene clusters of bacillomycin, mycosubtilin, fengycin, and macrolactin H in B. velezensis CCASU-C6 and bacillibactin and Macrolactin H in B. subtilis CCASU-C11 showed 100% conservation.

Predicting the Anti-SARS-CoV-2 Potential of Isoquinoline Alkaloids from Brazilian Siparunaceae Species Using Chemometric Tools.

The COVID-19 pandemic has caused over 7 million deaths globally in the past four years. Siparuna spp. (Siparunaceae), which is used in Brazilian folk medicine, is considered a genus with potential antiviral alternatives. This study explored the correlation between phytochemicals in Siparuna leaf extracts (S. ficoides, S. decipiens, S. glycycarpa, S. reginae, and S. cymosa) and their potential against various SARS-CoV-2 targets. In vitro assays examined interactions between the spike protein and the ACE2 receptor, protease activity, and viral replication inhibition in Calu-3 cell models. UHPLC-MS/MS analysis, processed with MZmine and evaluated chemometrically, revealed isoquinoline alkaloids with bulbocapnine, showing promising therapeutic potential. Predictions regarding absorption, distribution, metabolism, excretion, and toxicity were conducted, along with molecular docking and dynamics simulations, to evaluate protein-ligand interaction stability. The results confirmed the antiviral activity of the Siparuna genus against SARS-CoV-2 targets, with 92% of the extracts maintaining over 70% cellular viability at 200 μg·mL-1 and 80% achieving more than 50% viral activity suppression at 50 μg·mL-1. These findings highlight the potential of isoquinoline alkaloids as novel anti-coronavirus agents and support the need for further exploration, isolation, and testing of Siparuna compounds in the fight against COVID-19.

MRNA vaccines with RBD mutations have broad-spectrum activity against SARS-CoV-2 variants in mice

The emergence of SARS-CoV-2 variants with defined mutations that enhance pathogenicity or facilitate immune evasion has resulted in a continual decline in the protective efficacy of existing vaccines. Therefore, there is a pressing need for a vaccine capable of combating future variants. In this study, we designed new mRNA vaccines, BSCoV05 and BSCoV06, and generated point mutations in the receptor-binding domain (RBD) of the original Wuhan strain to increase their broad-spectrum antiviral activity. Additionally, we used the BA.1 RBD as a control. Both vaccines elicited a robust immune response in BALB/c and K18-hACE2 mice, generating high levels of specific binding antibodies against the BA.2 RBD. Moreover, all three vaccines induced neutralizing antibodies against the prototype viral strain and relevant variants, including the Alpha and Beta strains and the Omicron variants BA.1, BA.2, BA.5, XBB.1.5, XBB.1.16, EG.5.1, and EG.5.1.1, with BSCoV06 demonstrating broader neutralizing antibody activity. Both BSCoV05 and BSCoV06 also elicited a cellular immune response. After the challenge, both BSCoV05 and BSCOV06 provided protection against the EG.5.1 strain in both mouse strains. Therefore, these two vaccines merit further evaluation in nonhuman primates, and this vaccine design strategy should be explored for its potential application in combating future SARS-CoV-2 variants, offering valuable insights into broad-spectrum vaccine development.

Oral obeldesivir provides postexposure protection against Marburg virus in nonhuman primates.

The recent outbreak of Marburg virus (MARV) in Rwanda underscores the need for effective countermeasures against this highly fatal pathogen, with case fatality rates reaching 90%. Currently, no vaccines or approved treatments exist for MARV infection, distinguishing it from related viruses like Ebola. Our research demonstrates that the oral drug obeldesivir (ODV), a nucleoside analog prodrug, shows promising antiviral activity against filoviruses in vitro and offers significant protection in animal models. In this study with cynomolgus macaques (n=6), a 10-day regimen of once-daily ODV, initiated 24 hours post-exposure, provided 80% protection against a thousand-fold lethal MARV challenge, delaying viral replication and disease onset. Transcriptome analysis revealed that early adaptive responses correlated with successful outcomes. Compared to intravenous options, oral antivirals like ODV offer logistical advantages in outbreak settings, enabling easier administration and broader contact coverage. Our findings support ODV's potential as a broad-spectrum, oral postexposure prophylaxis for filoviruses.

Discovery of a 2'-α-Fluoro-2'-β-C-(fluoromethyl) Purine Nucleotide Prodrug as a Potential Oral Anti-SARS-CoV-2 Agent.

A novel 2'-α-fluoro-2'-β-C-(fluoromethyl) purine nucleoside phosphoramidate prodrug 15 has been designed and synthesized to treat SARS-CoV-2 infection. The SARS-CoV-2 central replication transcription complex (C-RTC, nsp12-nsp7-nsp82) catalyzed in vitro RNA synthesis was effectively inhibited by the corresponding bioactive nucleoside triphosphate (13-TP). The cryo-electron microscopy structure of the C-RTC:13-TP complex was also determined. Compound 15 exhibited potent in vitro antiviral activity against the SARS-CoV-2 20SF107 strain (EC50 = 0.56 ± 0.06 μM) and the Omicron BA.5 variant (EC50 = 0.96 ± 0.23 μM) with low cytotoxicity. Furthermore, it was well tolerated in rats at doses of up to 2000 mg/kg, and a single oral dose of this prodrug at 40 mg/kg led to high levels of 13-TP in the target organ lungs of rats with a long half-life. These findings support the further development of compound 15 as an orally available antiviral agent for the treatment of SARS-CoV-2 infection.

LncRNA NORAD modulates STAT3/STAT1 balance and innate immune responses in human cells via interaction with STAT3

Long non-coding RNAs (lncRNAs) are pivotal regulators of cellular processes. Here we reveal an interaction between the lncRNA NORAD, noted for its role in DNA stability, and the immune related transcription factor STAT3 in embryonic and differentiated human cells. Results from NORAD knockdown experiments implicate NORAD in facilitating STAT3 nuclear localization and suppressing antiviral gene activation. In NORAD-deficient cells, STAT3 remains cytoplasmic, allowing STAT1 to enhance antiviral activity. Analysis of RNA expression data from in vitro experiments and clinical samples demonstrates reduced NORAD upon viral infection. Additionally, evolutionary conservation analysis suggests that this regulatory function of NORAD is restricted to humans, potentially owing to the introduction of an Alu element in hominoids. Our findings thus suggest that NORAD functions as a modulator of STAT3-mediated immune suppression, adding to the understanding of lncRNAs in immune regulation and evolutionary adaptation in host defense mechanisms.

Uncovering Antiviral Potential of Cistus ladanifer Extracts Against HSV-1 and SARS-CoV-2 by In Vitro and In Silico Analysis.

Infectious diseases remain a major global health concern. Cistus ladanifer, a plant commonly employed in Moroccan traditional medicine, has been identified as a potential antiviral candidate. This study aimed to evaluate the antiviral activity of C. ladanifer extracts in vitro and in silico against two respiratory viruses: Herpes simplex virus and the severe acute respiratory syndrome coronavirus 2 variants of concern Delta and Omicron. Toxic prediction of the main compounds identified by Gas Chromatography-Mass Spectrometry from Cistus ladanifer was performed in silico via ProTox-II software. Molecular docking was subsequently performed via Maestro version 11.5 software from Schrödinger to gain a comprehensive understanding of their biological activity. The extracts were subjected to in vitro antiviral screening against the selected strains via real-time RT‒qPCR. Our docking estimation supported the in vitro results, and a diverse array of compounds extracted from Cistus ladanifer demonstrated significant antiviral activity with a low toxicity profile. Accordingly, in vitro data revealed a dose-dependent effect of the studied extracts, with particular efficacy against the Omicron variant. With the antiviral evaluation and docking outcomes in hand, we suggest a plausible mechanism of action for these compounds through further investigation into the effectiveness of Cistus ladanifer against other respiratory viruses.

Eco-sustainable chromatographic method for the determination of favipiravir and nitazoxanide for COVID-19: application to human plasma

Coronavirus disease 2019 (COVID-19), an extremely contagious illness, has posed enormous challenges to healthcare systems around the world. Although the evidence on COVID-19 management is growing, antiviral medication is still the first line of treatment. Therefore, it is critical that effective, safe, and tolerable antivirals be available to treat early COVID-19 and stop its progression. Recently, favipiravir (FAV) has received FDA approval as safe and effective antiviral medication for COVID-19 management. Nitazoxanide (NTZ) also possesses antiviral and immunomodulating activities. Moreover, FAV and NTZ in combination are clinically used in COVID-19 treatment with reported safety, synergistic antiviral and immunomodulating effects. Despite the availability of various clinical studies on both FAV and NTZ, no existing analytical application for the simultaneous estimation of FAV and NTZ exists. As a result, the current work goal is to establish a green HPLC method for their analysis and implementation to human plasma. The developed method utilizes isocratic elution with 0.1% aqueous formic acid: ethanol (55:45, v/v) and dantrolene as internal standard. The bioanalytical validation parameters passed the FDA acceptance criteria. NEMI, eco scale, AGREE and ComplexGAPI approaches were used for qualitative and quantitative evaluation of the method’s greenness.