In Vitro Virucidal Effects of Ultraviolet Light Prototypes on RNA viruses.

Ultraviolet-C (UVC) has been used to cause virus inactivation. The virucidal activity of three UV light lamps [UVC high frequencies (HF), UVC+B LED and UVC+A LED] was evaluated against the enveloped feline coronavirus (FCoVII), a surrogate model of SARS-CoV-2, the enveloped vesicular stomatitis virus (VSV), and the naked encephalomyocarditis virus (EMCV). Virucidal assays were performed at different time points of UV-light exposure (i.e., 5, 30 minutes and 1, 6, and 8 hours), placing each virus 180 cm below the perpendicular irradiation of the lamp and 1 and 2 meters from the perpendicular axis. We found that the UVC HF lamp had virucidal effects (≥96.8% of virus inactivation) against FCoVII, VSV and EMCV after 5 minutes of irradiation at each distance analyzed. Moreover, the UVC+B LED lamp had the highest inhibitory effects on FCoVII and VSV infectivity (≥99% of virus inactivation) when these viruses were settled below the perpendicular axis of the lamp for 5 minutes. Conversely, the UVC+A LED lamp was the least effective, achieving ≥85.9% inactivation of enveloped RNA viruses after 8 hours of UV exposure. Overall, UV light lamps, and in particular UVC HF and UVC+B LED ones, had a rapid and strong virucidal activity against distinct RNA viruses, including coronaviruses.

In Vitro Potential Virucidal Effect Evaluation of Xibornol on Human Adenovirus Type 5, Human Rhinovirus Type 13, Human Coronavirus 229E, Human Parainfluenza Virus Type 1, and Human Respiratory Syncytial Virus.

The availability of virucidal compounds to reduce the impact of respiratory viruses is a relevant topic for public health, especially during the recent coronavirus disease (COVID-19) pandemic. Antimicrobial properties of Xibornol are known since the 1970s, but its activity on viruses is currently little explored. In this study, Xibornol activity at a fixed concentration of 0.03 mg/100 ml has been evaluated on five respiratory viruses (Human Adenovirus 5, Human Rhinovirus type 13, Human Coronavirus 229E, Human Parainfluenza Virus type 1, and Human Respiratory Syncytial Virus) through in vitro experiments based on adapted European standard UNI EN 14476-20019. The experiments were carried out under two different environmental conditions, one with the addition of fetal bovine serum to simulate an in vivo condition (dirty condition) and the other without the addition of any organic substances (clean condition). The viral abatement of Xibornol (expressed as Log10 reduction - LR) was statistically significant under both clean and dirty environmental conditions. Namely, in clean condition, LR ranged from 2.67 to 3.84, while in the dirty one the abatement was slightly lower (from 1.75 to 3.03). Parainfluenza Virus and Human Adenovirus were most resistant compared to the other viruses. The obtained data confirmed Xibornol activity and its use as topic substance for viral inactivation to prevent upper respiratory tract disease.

[Antiviral and virucidal activity of sodium deoxyribonucleate and its complex with iron against viruses of different kingdoms and families].

INTRODUCTION: The urgent problem of modern medicine is the fight against acute respiratory viral infections (ARVI). To combat ARVI, drugs of wide antiviral potency are needed, as well as immunomodulating drugs. Such antiviral and immunomodulatory effects has sodium deoxyribonucleate (DNA-Na) and its complex with iron (DNA-Na-Fe) developed on the basis of double-stranded DNA of natural origin. AIM OF THE STUDY: To assess antiviral and virucidal activity of DNA-Na and DNA-Na-Fe against viruses of different kingdoms and families. MATERIALS AND METHODS: Antiviral and virucidal activity of DNA-Na and DNA-Na-Fe was assessed in cell cultures infected with viruses. RESULTS AND DISCUSSION: DNA-Na and DNA-Na-Fe had antiviral activity against adenovirus at concentrations of 2501000 mcg/ml. Antiviral effect of both drugs was not detected in case of poliovirus. DNA-Na and DNA-Na-Fe had antiviral activity against coronavirus in all administration schemes. EC50 for DNA-Na ~ 2500 mcg/ml, for DNA-Na-Fe ~ 1000 mcg/ml. In cells treated with DNA-Na-Fe, secretion of following proinflammatory cytokines was detected: Interleukin (IL) 1, IL-2, IL-6, IL-18, interferon- (IFN-), IFN-, as well as anti-inflammatory cytokines: IL-4, IL-10, antagonist of IL-1 receptor. Evidently, DNA-Na and DNA-Na-Fe have antiviral effect, but mechanism of action does not seem to be associated with specific effect on viral replication. Presence of virucidal activity of drugs against representatives of Coronaviridae, Adenoviridae, Picornaviridae, Retroviridae, Herpesviridae in vitro test in range of 1.03.0 lg TCID50 was identified. CONCLUSION: Presence of simultaneous antiviral and virucidal activity of DNA-Na and DNA-Na-Fe against adeno- and coronaviruses shows their prospects for prevention and treatment of ARVI.

Low Concentration Ozone for Surface Disinfection against Sars-Cov-2 and Feline Coronavirus

Intro: Surface and environment disinfection is an important part of infection control strategies, especially in the ongoing COVID-19 pandemic. Ozone, a highly reactive oxidant, is a widely used disinfectant in many industries including food, healthcare and water treatment. It has a broad-spectrum activity and leaves no harmful residues. However, most demonstrated efficacy has been at high ozone levels (>1ppm) which can be harmful to humans in case of exposure. Here, we undertook a study to evaluate if exposure to ozone is effective in inactivating SARS-CoV-2 and feline coronavirus (FCoV) even at low concentrations. Method(s): Ozone at 0.07, 0.1 and 1.2 ppm were evaluated for its virucidal activity against SARS-CoV-2 and FCoV. An ozone gas generator (Medklinn Air + Surface Sterilizer (CerafusionTM Technology), Medklinn, Malaysia) supplied controlled levels of ozone to a custom-built chamber of 1.5 ft3 (1.5ft x 1ft x 1ft) where dry virus films containing 1 x 104 PFU of test virus were exposed to ozone gas for 0.5h, 1h, 3h, 5h, and 8h. The experiment was performed at ambient temperature (23-24oC) and relative humidity (RH) of 55% (FCoV only) and 85% (SARS-CoV-2 and FCoV). Finding(s): At low level of ozone of 0.1ppm, >90% reduction of both viruses was achieved after 3h exposure at 85% and 55% humidity. At 1.2ppm, >90% reduction of both viruses was achieved after 0.5h exposure at 85% humidity. Ozone at 0.07ppm, however, did not show good efficacy as reduction not exceeding 90% was achieved only after 8h exposure at 85% and 55% humidity. Conclusion(s): The study demonstrated that low concentration of ozone of at least 0.1 ppm reduced SARS-CoV-2 and FCoV by >90% when used at 85% humidity. The use of low level ozone presents a safer alternative for disinfecting enclosed spaces and greatly reduces any potential harmful health effects in case of accidental exposure.Copyright © 2023

Virucidal activity in vitro of mouthwashes against a feline coronavirus type II.

Transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can occur through saliva and aerosol droplets deriving from the upper aerodigestive tract during coughing, sneezing, talking, and even during oral inspection or dental procedures. The aim of this study was to assess in vitro virucidal activity of commercial and experimental mouthwashes against a feline coronavirus (FCoV) strain. Commercial and experimental (commercial-based products with addition of either sodium dodecyl sulfate (SDS) or thymus vulgaris essential oil (TEO) at different concentrations) mouthwashes were placed in contact with FCoV for different time intervals, that is, 30 s (T30), 60 s (T60), and 180 s (T180); subsequently, the virus was titrated on Crandell Reese Feline Kidney cells. An SDS-based commercial mouthwash reduced the viral load by 5 log10 tissue culture infectious dose (TCID)50 /50 µl at T30 while a cetylpyridinium (CPC)-based commercial mouthwash was able to reduce the viral titer of 4.75 log10 at T60. Furthermore, five experimental mouthwashes supplemented with SDS reduced the viral titer by 4.75-5 log10 according to a dose- (up to 4 mM) and time-dependent fashion.

Rapid Virucidal Activity of Japanese Saxifraga Species-Derived Condensed Tannins against SARS-CoV-2, Influenza A Virus, and Human Norovirus Surrogate Viruses.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus (IAV), and norovirus are global threats to human health. The application of effective virucidal agents, which contribute to the inactivation of viruses on hands and environmental surfaces, is important to facilitate robust virus infection control measures. Naturally derived virucidal disinfectants have attracted attention owing to their safety and eco-friendly properties. In this study, we showed that multiple Japanese Saxifraga species-derived fractions demonstrated rapid, potent virucidal activity against the SARS-CoV-2 ancestral strain and multiple variant strains, IAV, and two human norovirus surrogates: feline calicivirus (FCV) and murine norovirus (MNV). Condensed tannins were identified as active chemical constituents that play a central role in the virucidal activities of these fractions. At a concentration of 25 µg/mL, the purified condensed tannin fraction Sst-2R induced significant reductions in the viral titers of the SARS-CoV-2 ancestral strain, IAV, and FCV (reductions of ≥3.13, ≥3.00, and 2.50 log10 50% tissue culture infective doses [TCID50]/mL, respectively) within 10 s of reaction time. Furthermore, at a concentration of 100 µg/mL, Sst-2R induced a reduction of 1.75 log10 TCID50/mL in the viral titers of MNV within 1 min. Western blotting and transmission electron microscopy analyses revealed that Sst-2R produced structural abnormalities in viral structural proteins and envelopes, resulting in the destruction of viral particles. Furthermore, Saxifraga species-derived fraction-containing cream showed virucidal activity against multiple viruses within 10 min. Our findings indicate that Saxifraga species-derived fractions containing condensed tannins can be used as disinfectants against multiple viruses on hands and environmental surfaces. IMPORTANCE SARS-CoV-2, IAV, and norovirus are highly contagious pathogens. The use of naturally derived components as novel virucidal/antiviral agents is currently attracting attention. We showed that fractions from extracts of Saxifraga species, in the form of a solution as well as a cream, exerted potent, rapid virucidal activities against SARS-CoV-2, IAV, and surrogates of human norovirus. Condensed tannins were found to play a central role in this activity. The in vitro cytotoxicity of the purified condensed tannin fraction at a concentration that exhibited some extent of virucidal activity was lower than that of 70% ethanol or 2,000 ppm sodium hypochlorite solution, which are popular virucidal disinfectants. Our study suggests that Saxifraga species-derived fractions containing condensed tannins can be used on hands and environmental surfaces as safe virucidal agents against multiple viruses.

Scientific Evaluation of the Remedies Used in Turkish Folk Medicine to Treat Possible Viral Infections

Background: Plants, with their rich phytochemical treasury, are one of the main sources of drug development. However, a randomized search on plant sources for the discovery of phyto-chemicals with specified pharmacological activity is expensive and tedious. Therefore, it is logical to constrain the sources to increase success. In the recent four decades, the importance of traditional information has been recognized by the scientific community. Consequently, interest in field sur-veys for the documentation of traditional worldwide medicines has significantly increased. Method(s): Infectious diseases induced by pathogenic bacteria, fungi, or viruses have been one of the most common health problems for the public, for which traditional remedies have been practiced. Since laypeople could not distinguish the microbial origin of the infection, the remedies used for treatment could not be delineated. The aim of this study was first to search the plants used in Turkish folk medicine for such infectious diseases. The second step was to find scientific evidence in the online databases for the frequently quoted plants whether they may have potential activity against virus replication. Result(s): A reference survey on the most frequently quoted plants revealed that 16 out of 17 were shown to possess virucide or inhibitory effects on the replication of various viruses. Conclusion(s): Since each virus type may have a different viral replication pattern, further detailed in-vestigations should be carried out to reveal their exact antiviral potentials.Copyright © 2023 Bentham Science Publishers.

Discovery of novel papain-like protease inhibitors for potential treatment of COVID-19.

The recent emergence of different SARS-CoV-2 variants creates an urgent need to develop more effective therapeutic agents to prevent COVID-19 outbreaks. Among SARS-CoV-2 essential proteases is papain-like protease (SARS-CoV-2 PLpro), which plays multiple roles in regulating SARS-CoV-2 viral spread and innate immunity such as deubiquitinating and deISG15ylating (interferon-induced gene 15) activities. Many studies are currently focused on targeting this protease to tackle SARS-CoV-2 infection. In this context, we performed a phenotypic screening using an in-house pilot compounds collection possessing a diverse skeleta against SARS-CoV-2 PLpro. This screen identified SIMR3030 as a potent inhibitor of SARS-CoV-2. SIMR3030 has been shown to exhibit deubiquitinating activity and inhibition of SARS-CoV-2 specific gene expression (ORF1b and Spike) in infected host cells and possessing virucidal activity. Moreover, SIMR3030 was demonstrated to inhibit the expression of inflammatory markers, including IFN-α, IL-6, and OAS1, which are reported to mediate the development of cytokine storms and aggressive immune responses. In vitro absorption, distribution, metabolism, and excretion (ADME) assessment of the drug-likeness properties of SIMR3030 demonstrated good microsomal stability in liver microsomes. Furthermore, SIMR3030 demonstrated very low potency as an inhibitor of CYP450, CYP3A4, CYP2D6 and CYP2C9 which rules out any potential drug-drug interactions. In addition, SIMR3030 showed moderate permeability in Caco2-cells. Critically, SIMR3030 has maintained a high in vivo safety profile at different concentrations. Molecular modeling studies of SIMR3030 in the active sites of SARS-CoV-2 and MERS-CoV PLpro were performed to shed light on the binding modes of this inhibitor. This study demonstrates that SIMR3030 is a potent inhibitor of SARS-CoV-2 PLpro that forms the foundation for developing new drugs to tackle the COVID-19 pandemic and may pave the way for the development of novel therapeutics for a possible future outbreak of new SARS-CoV-2 variants or other Coronavirus species.

Virucidal efficacy of household dishwashers

Not only since SARS-CoV-2, have transmission routes of viruses been of interest. Noroviruses e.g., can be transmitted via smear infection, are relatively stable in the environment and very resistant to chemical disinfection. Some studies determined the virucidal efficacy of laundering processes, but few studies focused on the virucidal efficacy of dishwashing processes. Here, especially consumer related conditions are of interest. Households for example are a hotspot of norovirus infection and thus a sufficient reduction of these and other viruses from dishes must be insured to avoid an infection via this route. The likelihood of such an event should not be underestimated, since it was shown that the washing machine can be a reservoir for the transmission of extended spectrum beta-lactamase producing bacteria in newborns. Although viruses do not replicate in these devices a transmission via contaminated cutlery e.g., cannot be excluded. Using a consumer related approach to determine the virucidal efficacy of dishwashers, we found a combination of a bleach containing dishwasher detergent, a cleaning temperature of 45 C for 45 min and a rinsing temperature of 50 C, to be sufficient to reduces viral titer of bovine corona virus, murine norovirus and modified vaccinia virus by 4.8, 4.2 and 3.8 logarithmic stages respectively.Copyright © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

HOCl as a Promising Candidate for Effective Containment of Covid 19 From Biological and Non-Biological Surfaces

Covid 19 is a pandemic disease spread almost in the whole world. To date, no medical advancement to curb the virus. Coronavirus is an enveloped virus transmitted from the biological and non-biological surface by direct or indirect contact. Limited literature revealed that the enveloped virus can be killed by disinfectants. There are many biocidal agents used for decontamination of the virus, yet they have many issues like toxicity, killing time, activation requirement, etc. Some are specific to the inanimate surface but not used by a human being. This current situation showed an urgent need for a biocidal agent which can act on biological as well as non-biological surfaces without any potential toxicity. Moreover, it should be easy to handle, inexpensive, and safe for the environment. Hypochlorous acid is a weak acid that acts as a powerful disinfectant and shows biocidal efficacy against a wide range of microorganisms. Hypochlorous acid is simple to use, inexpensive, eco-friendly, non-toxic, and stable. The properties of HOCl can be regulated at the site of preparation and therefore, its compliance is high. Hypochlorous acid seems to be a promising agent in disinfection and sterilization in healthcare facilities. Due to its diverse biocidal actions, it may be used as a potent disinfectant against novel coronavirus.Copyright © 2022 Bentham Science Publishers.

Virucidal Activity of Lemon Essential Oil against Feline Calicivirus Used as Surrogate for Norovirus.

Norovirus (NoV) is regarded as a common cause of acute gastrointestinal illness worldwide in all age groups, with substantial morbidity across health care and community settings. The lack of in vitro cell culture systems for human NoV has prompted the use of cultivatable caliciviruses (such as feline calicivirus, FCV, or murine NoV) as surrogates for in vitro evaluation of antivirals. Essential oils (EOs) may represent a valid tool to counteract viral infections, particularly as food preservatives. In the present study, the virucidal efficacy of lemon EO (LEO) against FCV was assessed in vitro. The gas chromatography hyphenated with mass spectrometry (GC/MS) technique was used to reveal the chemical composition of LEO. The following small molecules were detected as major components of LEO: limonene (53%), ß-pinene (14.5%), γ-terpinene (5.9%), citral (3.8%), α-pinene (2.4%), and ß-thujene (1.94%). LEO at 302.0 µg/mL, exceeding the maximum non cytotoxic limit, significantly decreased viral titre of 0.75 log10 TCID50/50 µL after 8 h. Moreover, virucidal activity was tested using LEO at 3020.00 µg/mL, determining a reduction of viral titre as high as 1.25 log10 TCID50/50 µL after 8 h of time contact. These results open up perspectives for the development of alternative prophylaxis approaches for the control of NoV infection.

Cuprous oxide nanoparticles incorporated into a polymeric matrix embedded in fabrics to prevent spread of SARS-CoV-2.

This paper describes the development of a coating for cotton and polypropylene (PP) fabrics based on a polymeric matrix embedded with cuprous oxide nanoparticles (Cu2O@SDS NPs) in order to inactivate SARS-CoV-2 and manufactured by a simple process using a dip-assisted layer-by-layer technology, at low curing temperature and without the need for expensive equipment, capable of achieving disinfection rates of up to 99%. The polymeric bilayer coating makes the surface of the fabrics hydrophilic, enabling the transportation of the virus-infected droplets to achieve the rapid inactivation of SARS-CoV-2 by contact with the Cu2O@SDS NPs incorporated in the coated fabrics.

Synthesis of Novel 1,3,4-Oxadiazole-Derived α-Aminophosphonates/α-Aminophosphonic Acids and Evaluation of Their In Vitro Antiviral Activity against the Avian Coronavirus Infectious Bronchitis Virus.

An efficient and simple approach has been developed for the synthesis of eight dialkyl/aryl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(aryl)methyl]phosphonates through the Pudovik-type reaction of dialkyl/arylphosphite with imines, obtained from 5-phenyl-1,3,4-oxadiazol-2-amine and aromatic aldehydes, under microwave irradiation. Five of them were hydrolyzed to lead to the corresponding phosphonic acids. Selected synthesized compounds were screened for their in vitro antiviral activity against the avian bronchitis virus (IBV). In the MTT cytotoxicity assay, the dose-response curve showed that all test compounds were safe in the range concentration of 540-1599 µM. The direct contact of novel synthesized compounds with IBV showed that the diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethoxyphenyl)methyl]phosphonate (5f) (at 33 µM) and the [(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl] phosphonic acid (6a) (at 1.23 µM) strongly inhibited the IBV infectivity, indicating their high virucidal activity. However, virus titers from IBV-infected Vero cells remained unchanged in response to treatment with the lowest non-cytotoxic concentrations of synthesized compounds suggesting their incapacity to inhibit the virus replication inside the host cell. Lack of antiviral activity might presumably be ascribed to their polarity that hampers their diffusion across the lipophilic cytoplasmic membrane. Therefore, the interactions of 5f and 6a were analyzed against the main coronavirus protease, papain-like protease, and nucleocapsid protein by molecular docking methods. Nevertheless, the novel 1,3,4-oxadiazole-based α-aminophosphonic acids and α-amino-phosphonates hold potential for developing new hygienic virucidal products for domestic, chemical, and medical uses.

Efficient Inactivation of Monkeypox Virus by World Health Organization‒Recommended Hand Rub Formulations and Alcohols.

Increasing nonzoonotic human monkeypox virus (MPXV) infections urge reevaluation of inactivation strategies. We demonstrate efficient inactivation of MPXV by 2 World Health Organization‒recommended alcohol-based hand rub solutions. When compared with other (re)emerging enveloped viruses, MPXV displayed the greatest stability. Our results support rigorous adherence to use of alcohol-based disinfectants.

Disinfectants against SARS-CoV-2: A Review.

The pandemic due to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has emerged as a serious global public health issue. Besides the high transmission rate from individual to individual, indirect transmission from inanimate objects or surfaces poses a more significant threat. Since the start of the outbreak, the importance of respiratory protection, social distancing, and chemical disinfection to prevent the spread of the virus has been the prime focus for infection control. Health regulatory organizations have produced guidelines for the formulation and application of chemical disinfectants to manufacturing industries and the public. On the other hand, extensive literature on the virucidal efficacy testing of microbicides for SARS-CoV-2 has been published over the past year and a half. This review summarizes the studies on the most common chemical disinfectants and their virucidal efficacy against SARS-CoV-2, including the type and concentration of the chemical disinfectant, the formulation, the presence of excipients, the exposure time, and other critical factors that determine the effectiveness of chemical disinfectants. In this review, we also critically appraise these disinfectants and conduct a discussion on the role they can play in the COVID-19 pandemic.

Broad antiviral effects of Echinacea purpurea against SARS-CoV-2 variants of concern andpotential mechanism of action

Introduction SARS-CoV-2 variants of concern (VOCs) represent an alarming threat as they may escape vaccination effectiveness. Broad-spectrum antivirals could complement and further enhance preventive benefits achieved through SARS-CoV-2 vaccination campaigns. Aim Testing the antiviral activity of Echinacea purpurea against VOCs and exploring underlying modes-of-action. Method A hydroethanolic extract of freshly harvested E. purpurea herb and roots (Echinaforce®, EF extract) was tested to inhibit infection of VOCs B1.1.7 (alpha), B.1.351.1 (beta), P.1 (gamma), B1.617.2 (delta), AV.1 (Scottish) and B1.525 (eta). Molecular dynamics (MD) were used to study interaction of EF phytochemical markers with known pharmacological viral and host cell targets. Results EF broadly inhibited propagation of all tested SARS-CoV-2 VOCs at EC50 < 12.0 ;jg/ml. Treatment of epithelial cells with 20 jg/ml EF prevented sequential infection with SARS-CoV-2 (Hu-1). MD analyses showed for alkylamides, caftaric acid and feruoyl-tartaric constant binding affinity to spike proteins of all VOCs and to TMPRSS-2, a serine protease required for virus endocytosis. Conclusion EF extract exhibits virucidal activity against all tested SARS-CoV-2 VOCs and protects epithelial cells from infection.

UV-C light-based surface disinfection: Analysis of its virucidal efficacy using a bacteriophage model

Introduction Reprocessing of medical devices becomes increasingly complex, due to higher hygiene requirements. Former studies revealed satisfactory bactericidal properties of UV-C light disinfection in otorhinolaryngological endoscopes. Especially in the context of the current COVID-19 pandemic, virucidal properties are of high importance. In this study the virucidal efficacy of UV-C light disinfection was analyzed using a bacteriophage model. Materials and methods MS-2 bacteriophages were used as surrogate for stable viruses with high tenacity. The bacteriophage samples were irradiated for up to three cycles of 25 seconds by UV-C light (D25, UV-Smart Technologies B.V.). A dilution series of the irradiated test samples was mixed with 1x108 CFU of Escherichia coli. After incubation plaque formation of Escherichia coli were counted and hence the phage concentration was determined. Results The initial contamination of the test samples was 1.8x1012 plaque forming units (pfu). After 25 seconds of UV-C light irradiation, a non-significant Log reduction of 2.2 was found (p = 0,82). After 50 and 75 seconds of UV-exposure a significant Log reduction of 3.4 e.g. 5.1 (p = 0.05 e.g. p = 0.004) was found. The control sample showed a titer of 1.2 x 1010 pfu. Conclusion The tested UV system seems to provide a significant virucidal effect after a short time of exposure. In combination with the results of the bacteriological testing it appears suitable for clinical use as a substitute for current disinfection methods.

Anti-Coronavirus Efficiency and Redox-Modulating Capacity of Polyphenol-Rich Extracts from Traditional Bulgarian Medicinal Plants.

Background: The use of various herbal therapists as part of traditional medicine in different parts of the world, including Bulgaria, is due to the knowledge accumulated over the centuries by people about their valuable biological activities. In this study, we investigate extracts from widely used Bulgarian medicinal plants for their ability to prevent the coronavirus infection of cells by testing different mechanisms of antiviral protection, their polyphenol content, and redox-modulating capacity. Methods: The influence on the stage of viral adsorption, the inhibition of extracellular virions, and the protective effect on uninfected cells of the plant's extracts were reported by the end-point dilution method, and virus titer (in Δ lgs) was determined as compared to the untreated controls. The total content of polyphenols and flavonoids was also determined. We tested the antioxidant power of the extracts by their ability to inhibit the generation of superoxide anionic radicals and to scavenge DPPH radicals. We determined their iron-reducing, copper-reducing, and metal-chelating antioxidant powers. Results: Most of the extracts tested suppress the extracellular virions of HCov. They also inhibit the stage of viral adsorption to the host cell to varying degrees and have a protective effect on healthy cells before being subjected to viral invasion. The examined extracts contained significant levels of polyphenols and quercetin-like flavonoids and showed remarkable antioxidant, radical, and redox-modulating effects. Conclusions: All of these 13 extracts from Bulgarian medicinal plants tested can act as antioxidants and antiviral and symptomatic drugs for the management of coronavirus infection.

Bulgarian Medicinal Extracts as Natural Inhibitors with Antiviral and Antibacterial Activity.

BACKGROUND: Bulgaria is a country with a wide range of medicinal plants, with uses in traditional medicine dating back for centuries. METHODS: Disc diffusion assay was used to evaluate the antimicrobial activity of the plant extracts. A cytopathic effect inhibition test was used for the assessment of the antiviral activity of the extracts. The virucidal activity of the extracts, their influence on the stage of viral adsorption, and their protective effect on uninfected cells were reported using the end-point dilution method, and Δlgs was determined as compared to the untreated controls. RESULTS: The results of the study reveal that the antibacterial potential of G. glabra and H. perforatum extracts in Gram-positive bacteria is more effective than in Gram-negative bacteria. When applied during the replication of HSV-1 and HCov-OC-43, only some of the extracts showed weak activity, with SI between 2 to 8.5. Almost all tested extracts inhibited the extracellular virions of the studied enveloped viruses (HSV-1 and HCov-OC-43) to a greater extent than of the non-enveloped viruses (PV-1 and HAdV-5). They inhibited the stage of viral adsorption (HSV-1) in the host cell (MDBK) to varying degrees and showed a protective effect on healthy cells (MDBK) before they were subjected to viral invasion (HSV-1). CONCLUSION: The antipathogenic potential of extracts of H. perforatum and G. glabra suggests their effectiveness as antimicrobial agents. All 13 extracts of the Bulgarian medicinal plants studied can be used to reduce viral yield in a wide range of viral infections.

Cationic Surfactants as Disinfectants against SARS-CoV-2.

The virucidal activity of a series of cationic surfactants differing in the length and number of hydrophobic tails (at the same hydrophilic head) and the structure of the hydrophilic head (at the same length of the hydrophobic n-alkyl tail) was compared. It was shown that an increase in the length and number of hydrophobic tails, as well as the presence of a benzene ring in the surfactant molecule, enhance the virucidal activity of the surfactant against SARS-CoV-2. This may be due to the more pronounced ability of such surfactants to penetrate and destroy the phospholipid membrane of the virus. Among the cationic surfactants studied, didodecyldimethylammonium bromide was shown to be the most efficient as a disinfectant, its 50% effective concentration (EC50) being equal to 0.016 mM. Two surfactants (didodecyldimethylammonium bromide and benzalkonium chloride) can deactivate SARS-CoV-2 in as little as 5 s.