Search Results (124)

The ongoing emergence of antiviral drug resistance underscores the critical need for new broad-spectrum antiviral agents. Sulfonamides and their derivatives have emerged as promising candidates for the development of new antiviral therapeutics. In this study, a series of camphor-10-sulfonamide derivatives was synthesized through a feasible and sustainable synthetic approach starting from naturally available precursors and evaluated for antiviral properties. Their activity was examined against three structurally distinct viruses—herpes simplex virus type 1 (HSV-1), human coronavirus (HCoV-OC43), and feline calicivirus (FCV)—representing both DNA and RNA, enveloped and non-enveloped types. The compounds were examined for their effects on viral replication, the stage of viral adsorption to the cell, and extracellular virions. The weakest cytotoxicity and the most pronounced activity of all the tested substances was demonstrated by the tryptophan derivative 7a. A time-dependent inhibition of the stage of adsorption of HCoV-OC43 (Δlg = 2.0 at 120 min) and FCV (Δlg = 1.75 at 60 min) to susceptible cells was established, as well as virucidal activity on the three types of virions tested, with the most pronounced effect at 120 min—for HSV-1 (Δlg = 2.75) and Δlg = 2.0 for HCoV-OC43 and FCV. Molecular docking studies performed using Glide (Schrödinger) provided insights into the active conformations of the most effective ligands and predicted possible interactions with relevant viral targets, supporting their potential as lead structures for further therapeutic development. Full article

Arboviruses such as dengue (DENV), Zika (ZIKV), and chikungunya (CHIKV) remain major global health threats, especially in tropical regions, with no effective antiviral treatments available. Recent research highlights progress in identifying antiviral compounds from natural sources against arboviruses belonging to the flavivirus genus, such as DENV and ZIKV. These compounds, derived from plants, marine organisms, and microorganisms, fall into several key chemical classes: quinones, flavonoids, phenolics, terpenoids, and alkaloids. Quinones inhibit viral entry and replication by targeting envelope proteins and proteases. Flavonoids disrupt RNA synthesis and show virucidal activity. Phenolic compounds reduce expression of non-structural proteins and inhibit enzyme function. Terpenoids demonstrate broad-spectrum activity against multiple arboviruses, while alkaloids interfere with early infection stages or viral enzymes. To support the reviewed literature, we performed molecular docking analyses of selected natural compounds and some arboviral proteins included as illustrative examples. These analyses support the structure–activity relationships reported for some natural compounds and highlight their potential interactions with essential viral targets such as the NS2B-NS3 protease and NS5 polymerase. Together, these literature and computational insights highlight the potential of natural products as scaffolds for antiviral drug development. Full article

The poultry industry is continually seeking efficient, practical strategies to control infectious diseases. Among these new alternatives are essential oils (EOs), naturally occurring compounds with antimicrobial properties. Their effectiveness has been demonstrated in various studies that focus on their broad antiviral properties. The present experiment evaluated the antiviral efficacy of an EOs formulation against the H7N3 subtype of avian influenza virus (AIV) by directly mixing virus and EOs (virus/EOs mixture) through an in vitro model in cultured Madin-Darby canine kidney cells (MDCKs). The experiment used a focus reduction neutralization test (FRNT) to determine the 50% inhibitory concentration (IC₅₀) by virus/EOs mixture, as well as the application of EOs 24 h before infection, through a viral inhibition test using a chicken embryo (CE) in ovo model. The results demonstrated the antiviral activity of the EOs formulation against the H7N3 in vitro model (IC₅₀ values of 20.4 and 38.3 ppm and selective index (SI) values of 9.4 and 5.1) and in ovo model (decreasing hemagglutination titers to 1 HA unit, 10^5.28 embryo infectious dose 50% (EID₅₀) per mL, and viral loads to approximately 10^11.4 copies/mL) when applied in CE, 24 h before viral infection, representing the lowest replication indicators recorded during the experiment. According to the results, the EOs formulation demonstrated antiviral activity against AIV H7N3 both as a virus/EOs mixture and through application in ovo 24 h before infection. Application 24 h before infection in CE showed a significant effect compared with the virus/EOs mixture, demonstrating an antiviral effect in the ovo infection model. This study demonstrates both the virucidal and antiviral capacity of the compounds in the EOs formulation against AIV H7N3 and their efficacy when applied 24 h before infection in the in ovo model. Full article

The transmission of viruses and bacteria via surfaces remains a persistent challenge for healthcare systems, leading to high public health costs and significant environmental impact due to the widespread use and disposal of single-use products. This study aims to evaluate the feasibility of using surface-covering films, based on biopolymers and inorganic nanoparticles, with strong antiviral and antibacterial properties, as a strategy to prevent infection transmission while offering a sustainable alternative to disposable materials. To this end, we developed a sprayable chitosan-based solution embedded with copper oxide nanoparticles (CH.CA@Cu). The solution demonstrated antibacterial activity against both Gram-positive and Gram-negative bacteria as well as virucidal activity, predominantly within one minute of exposure, against a wide range of viruses. After spraying various materials, the resulting film surfaces exhibited excellent adherence and uniform coverage, maintaining their integrity after contact. A field trial conducted in high-traffic environments confirmed the coating’s effectiveness. This long-lasting antiviral action supports their implementation, since the coated surface can continuously deactivate viruses regardless of infective doses of exposure, thereby reducing viral transmission. These findings will expand biopolymers’ current applicability while guiding us toward the adoption of green and eco-friendly technologies, thus reducing waste production. Full article

Background: Encapsulating essential oils in polymer-based nanocarriers can improve their stability, solubility, and bioavailability, while maintaining the biological activity of the oil’s active ingredients. In this contribution, we investigated the antiviral activity of Oregano Essential Oil (OEO) in its pure form and encapsulated into nanosized polymeric micelles, based on a poly(ethylene oxide)-block-poly(ε-caprolactone) diblock copolymer. Methods: The effect of encapsulation was evaluated using three structurally different viruses: herpes simplex virus type 1 (HSV-1) (DNA—enveloped virus), human coronavirus (HCoV OC-43) (RNA—enveloped virus), and feline calicivirus (FCV) (RNA—naked virus). The effect on the viral replicative cycle was determined using the cytopathic effect inhibition (CPE) test. Inhibition of the viral adsorption step, virucidal activity, and protective effect on healthy cells were assessed using the final dilution method and were determined as Δlg compared to the untreated viral control. Results: In both studied forms (pure and nanoformulated), OEO had no significant effect on viral replication. In the remaining antiviral experiments, the oil embedded into nanocarriers showed a slightly stronger effect than the pure oil. When the oil was directly applied to extracellular virions, viral titers were significantly reduced for all three viruses, with the effect being strongest for HSV-1 and FCV (Δlg = 3.5). A distinct effect was also observed on the viral adsorption stage, with the effect being most significant for HSV-1 (Δlg = 3.0). Conclusions: Pretreatment of healthy cells with the nanoformulated OEO significantly protected them from viral infection, with the greatest reduction in viral titer for HCoV OC-43. Full article

Norovirus (NoV) is a symptomatic virus that is the leading cause of gastrointestinal disease. It spreads easily through the fecal–oral route and contact with contaminated food or surfaces. Maintaining a high level of hygiene in food industry settings and refocusing food production on isolating and testing natural compounds that exhibit antimicrobial and antioxidant properties are important elements in preventing NoVs infection. This study evaluated plant extracts prepared by cold brew and cold concentrate techniques for their antioxidant and antiviral activity. The extracts obtained demonstrated high antioxidant activity, with notable variation depending on the plant material, ranging from moderate to very strong levels. Correspondingly, high antiviral potential was observed, reaching the nearly complete inactivation of the virus. Remarkably, the highest virucidal effects were already achieved at relatively elevated, but not maximal, antioxidant activity levels. The results of the study indicate that cold water extraction techniques allow for the obtention of plant extracts showing strong virus-inactivating activity and favorable antioxidant activity. Full article

Respiratory syncytial virus (RSV) infections have a significant impact on global health. Despite of recent advancements, the current treatment options for managing severe RSV infections remain primarily limited to supportive care, emphasizing the high priority for the development of effective antiviral therapies. Antiviral activity of 3,3′,4,4′,5,5′-hexahydroxy-trans-stilbene (HHS), a synthetic polyhydroxyphenol, has previously been demonstrated against SARS-CoV-2. In this study, we provide evidence for a direct virucidal effect of HHS against RSV infection in permissive HEp-2 cells in vitro. HHS, with an IC50 of 3.44 μM, efficiently inhibited HEp-2 cell infection with no sign of toxicity at least up to 25 μM. Interestingly, resveratrol, a polyhydroxyphenol analogue, was less efficient. Mode of action experiments revealed that HHS directly interacts with RSV particles, indicating that its virucidal activity is based on this interaction rather than affecting HEp-2 cells or post-infection processes. Together with previous data, our results suggest a broad antiviral activity of HHS against different respiratory viruses. Further studies are necessary to unveil the exact mechanism and evaluate the potential of HHS in the treatment of severe respiratory virus infections. Full article

Background: Ephedra przewalskii Stapf stems are a traditional Mongolian medicine commonly used to treat infectious diseases. Previous in vitro experiments have shown that the extract powder derived from its stems possesses antiviral activity. However, the active compounds responsible for this activity in E. przewalskii Stapf have not yet been identified or evaluated. This study aimed to identify the active components in E. przewalskii that exhibit antiviral effects against SARS-CoV-2 in vitro and validate their antiviral activity. Methods: E. przewalskii stem extracts were subjected to high-performance liquid chromatography with varying methanol ratios in the mobile phase to obtain fractions with different polarities. Antiviral activity was assessed by infecting VeroE6/TMPRSS2 cells with the SARS-CoV-2 Delta strain and treating them with the obtained fractions. Infectious titers were measured using the 50% tissue culture infective dose (TCID₅₀) method, and half-maximal inhibitory concentration (IC₅₀) values were calculated for each fraction. The active components in the two fractions with the highest antiviral activity were identified and structurally characterized by nuclear magnetic resonance analysis. The antiviral activity of these compounds was confirmed by adding them to SARS-CoV-2-infected cells and measuring their infectious titers using the TCID₅₀ method. The IC₅₀ values were also calculated. Viral-particle inactivation assays were conducted by mixing the extracts with SARS-CoV-2 and measuring infectious titers. Results: (−)-Catechin, (+)-epigallocatechin-(2α→O→7,4α→8)-(−)-epicatechin, and ent-epicatechin-(4α→8;2α→O→7)-catechin were isolated from E. przewalskii. These compounds exhibited significant antiviral activity against SARS-CoV-2 but demonstrated minimal direct virucidal effects. Conclusion: (−)-Catechin, (+)-epigallocatechin-(2α→O→7,4α→8)-(−)-epicatechin, and ent-epicatechin-(4α→8;2α→O→7)-catechin exhibit antiviral activity against SARS-CoV-2 in infected cells. Full article

Natural products possess a wide range of biological and biochemical potentials, with plant-derived compounds being significant sources for discovering new drugs. In this study, extracts of Vitex negundo and Macaranga tanarius prepared with different solvents were tested for their antiviral activity against the original SARS-CoV-2 Wuhan strain and its variants using plaque assay, quantitative real time RT-PCR, and immunofluorescence assay (IFA). Our results showed that at their maximum non-toxic concentrations, Vitex-Dichloromethane (DCM) and Macaranga extracts significantly inhibited SARS-CoV-2 Wuhan strain growth in Vero E6 cells, showing a 5-log reduction in plaque assay and confirmed by IFA. Meanwhile, Vitex-Hexane showed moderate activity with a 2-log decrease. The inhibition was shown in a dose-dependent manner. The antiviral efficacy of these extracts was further demonstrated against various SARS-CoV-2 variants including Alpha, Beta, Delta, and Omicron. Both Vitex-DCM and Macaranga showed strong virucidal activity. In addition, Vitex-DCM and Macaranga inhibited the transcriptional activity of purified SARS-CoV-2 RdRp, indicating that RdRp inhibition may contribute to viral suppression as shown at the post-infection stage. Furthermore, combining Vitex-DCM or Macaranga with remdesivir showed a synergistic effect against SARS-CoV-2. These results suggest that Vitex negundo and Macaranga tanarius extracts are promising candidates for anti-SARS-CoV-2 treatments. Their synergy with remdesivir also underscores the potential of drug combinations in fighting SARS-CoV-2 and preventing the emergence of mutant variants. Full article

Feline infectious peritonitis virus (FIPV), caused by a mutated form of feline coronavirus, poses a significant threat to feline health worldwide, with limited therapeutic options available. This study investigated the antiviral potential of α-mangostin (α-MG) and its enriched extracts (AMEs), obtained via microwave-assisted extraction, against FIPV. We evaluated their cytotoxicity, direct virucidal activity, and antiviral activity in CRFK cells. Both α-MG and AMEs demonstrated significant antiviral activity, with EC₅₀ values from 2.71 to 2.88 μg/mL and favorable selectivity indices (3.25–3.66). Notably, AMEs exhibited direct virucidal effects, effectively reducing viral titers. Furthermore, treatment with these compounds significantly reduced inflammatory cytokine expression (IFN-β, TNF-α, and IL-6 mRNA levels) and decreased viral loads in FIPV-infected cells. Drug combination studies using the ZIP model revealed enhanced cooperative effects when AMEs and α-MG were combined with GC-376 or GS-441524, with GC-376 combinations showing particularly strong synergistic potential. These findings suggest that α-MG and AMEs are promising candidates for FIPV treatment, either as monotherapy or in combination therapy. This study provides insights into developing novel therapeutic strategies to combat FIPV infections and offers a foundation for future veterinary antiviral drug development. Full article

Recently, essential rose oils and rose products have gained increasing importance in both the cosmetic and food industries, as well as in the composition of medicinal products. We investigated the in vitro antiviral activity of essential oil and floral water from Rosa damascena Mill against herpes simplex virus type 1 (HSV-1) infection in rabbit retinal cells (RRCs). The composition of the main chemical components in the rose essential oil was determined by means of gas chromatographic analysis. The effect on the viral replication cycle was determined using the cytopathic effect (CPE) inhibition assay. The virucidal activity, the effect on the adsorption stage of the virus to the host cell, and the protective effect on healthy cells were evaluated using the endpoint dilution method. The effects were determined as deviation in the viral titer, Δlg, for the treated cells from the one for the untreated viral control. The identified main active components of rose oil are geraniol (28.73%), citronellol (21.50%), nonadecane (13.13%), nerol (5.51%), heneicosane (4.87%), nonadecene (3.93), heptadecane (2.29), farnesol (2.11%), tricosane (1.29%), eicosane (1.01%), and eugenol (0.85%). The results demonstrated that both rose products do not have a significant effect on the virus replication but directly affect the viral particles and reduce the viral titer by Δlg = 3.25 for floral water and by Δlg = 3.0 for essential oil. Significant inhibition of the viral adsorption stage was also observed, leading to a decrease in the viral titers by Δlg = 2.25 for floral water and by Δlg = 2.0 for essential oil. When pretreating healthy cells with rose products, both samples significantly protected them from subsequent infection with HSV-1. This protective effect was more pronounced for the oil (Δlg = 2.5) compared to the one for the floral water (Δlg = 2.0). We used the in silico molecular docking method to gain insight into the mechanism of hindrance of viral adsorption by the main rose oil compounds (geraniol, citronellol, nerol). These components targeted the HSV-1 gD interaction surface with nectin-1 and HVEM (Herpesvirus Entry Mediator) host cell receptors, at N-, C-ends, and N-end, respectively. These findings could provide a structural framework for further development of anti-HSV-1 therapeutics. Full article

Toscana virus (TOSV) and Schmallenberg virus (SBV) are arthropod-borne viruses from the Bunyaviricetes class, posing significant human and animal health threats. TOSV, endemic to the Mediterranean region, is a notable human pathogen detected in various animals, suggesting potential zoonotic reservoirs. SBV emerged in Europe in 2011, affecting ruminants and causing reproductive issues, with substantial economic implications. The rapid spread of both viruses underscores the need for novel antiviral strategies. Host defense peptides (HDPs), particularly those derived from scorpion venom, are gaining attention for their antiviral potential. This study investigated pantinin-1 and pantinin-2 for their inhibitory activity against TOSV and SBV by plaque reduction assay, tissue culture infective dose (TCID₅₀) determination, and the analysis of M gene expression via qPCR. Both peptides exhibited potent virucidal activity, with IC₅₀ values of approximately 10 µM, depending on the specific in vitro cell model used. Additionally, the selectivity index (SI) values were favorable across all virus/cell line combinations, with particularly optimal results observed for pantinin-2. In human U87-MG neuronal cells, both peptides effectively blocked TOSV infection, a critical finding given the virus’s association with neurological conditions like encephalitis. The strong efficacy of these peptides against these viruses underscores the broader applicability of venom-derived peptides as promising antiviral agents, particularly in the context of emerging viral pathogens and increasing resistance to conventional therapeutics. Further studies are needed to optimize their antiviral potency and to assess their safety in vivo using animal models. Full article

Polyphenols are structurally diverse plant metabolites that have attracted significant interest. Their compositions are versatile, depending on their structures, including the number of rings in the polyphenol composition. Based on these attributes, polyphenols can be classified as flavanols, anthocyanins, flavones, phenolic acids, stilbenes, and lignans. Polyphenols mainly possess inhibition of viral replication, interference with viral protein synthesis, and modulation of immune responses, providing significant antiviral effects against several viruses, including herpes simplex virus, hepatitis C virus, and influenza. They are crucial for medical compounds in diverse, versatile treatments, namely in diabetes, cardiovascular disorders, cancer, and neurodegenerative problems. Plants are the primary source of bioactive molecules, which are valued for their anti-inflammatory, antioxidant, anticancer, and antiviral activities. Especially, polyphenols are extracted as the most abundant bioactive compounds of plants. Moreover, viral infections are one of the major factors in illnesses and diseases, along with bacteria and fungi. Numerous in vitro and in vivo studies report antiviral activity against SARS-CoV-2, Mayaro virus, dengue virus, herpesvirus, and influenza A virus, though clinical validation remains limited. Additionally, inhibition of viral entry, interference with viral replication, modulation of host immune response, and direct virucidal effects were examined. Full article

Background/Objectives: Airborne viral diseases pose a health risk, due to which there is a growing interest in developing filter materials capable of capturing fine particles containing virions from the air and that also have a virucidal effect. Nanofiber membranes made of poly(vinylidene fluoride) dissolved in N,N-dimethylacetamide and functionalized with copper, silver, and zinc nanoclusters were fabricated via electrospinning. This study aims to evaluate and compare the virucidal effects of nanofibers functionalized with metal nanoclusters against the human influenza A virus A/WSN/1933 (H1N1) and SARS-CoV-2. Methods: A comprehensive characterization of materials, including X-ray diffraction, scanning electron microscopy, microwave plasma atomic emission spectroscopy, thermogravimetric analysis, contact angle measurements, nitrogen sorption analysis, mercury intrusion porosimetry, filtration efficiency, and virucidal tests, was used to understand the interdependence of the materials’ physical characteristics and biological effects, as well as to determine their suitability for application as antiviral materials in air filtration systems. Results: All the filter materials tested demonstrated very high particle filtration efficiency (≥98.0%). The material embedded with copper nanoclusters showed strong virucidal efficacy against the SARS-CoV-2 alpha variant, achieving an approximately 1000-fold reduction in infectious virions within 12 h. The fibrous nanowire polymer functionalized with zinc nanoclusters was the most effective material against the human influenza A virus strain A/WSN/1933 (H1N1). Conclusions: The materials with Cu nanoclusters can be used with high efficiency to passivate and kill the SARS-CoV-2 alpha variant virions, and Zn nanoclusters modified activated porous membranes for killing human influenza A virus A7WSN/1933 (H1N1) virions. Full article

The diversity of structural types of carrageenans (CRGs)—sulfated polysaccharides of red algae—determines their different biological activities. The different types of CRGs (kappa, lambda, kappa/beta-CRGs) were isolated from the red algae of the Pacific coast. Molecular docking was performed to determine potential interactions of CRGs with the receptor-binding domain (RBD) of SARS-CoV-2 and its cellular receptor—angiotensin—converting enzyme type 2 (ACE2). CRGs interacted with ACE2 and RBD via hydrogen bonding and ionic interactions. The strongest binding affinity of CRGs and ACE2 was observed for kappa-CRG. Molecular docking was confirmed by results studying the effects of CRGs against SARS-CoV-2 in vitro. The ability of CRGs, as well as the complex CRG with sea urchin echinochrome (Ech), to inhibit SARS-CoV-2 replication in Vero E6 cells was studied using cytopathic effect (CPE) inhibition and RT-PCR assays. The simultaneous treatment of cells with CRGs and the virus revealed that kappa-CRG exhibited the most significant antiviral effect among all the polysaccharides, with a selective index (SI) of 33. The kappa-CRG/Ech complex exhibited the highest virucidal effect on SARS-CoV-2 particles with an SI above 70 (more than two times higher than that of CRG and Ech) and reduced viral RNA levels by 45% (IC = 45%). Our results illustrate that CRGs and kappa-CRG/Ech complex can act as protective agents against SARS-CoV-2. Full article