Repurposing Quaternary Ammonium Compounds as Potential Treatments for COVID-19

Challenges of quaternary ammonium antimicrobial agents: Mechanisms, resistance, persistence and impacts on the microecology

Quaternary ammonium compounds (QACs) served as broad spectrum antimicrobial agents are widely applied for surface disinfection, skin and mucous disinfection, and mouthwash. The daily applications of QACs have significantly increased, especially during the COVID-19 pandemic. However, the environmental residues of QACs have demonstrated harmful impacts on the environment, leading to an increase in environmental contamination, resistant microbes and disruption of microecology. The actions of QACs were related to their cationic character, which can impact the negatively charged cell membranes, but the details are still unclear. Moreover, bacteria with lower sensitivity and resistant pathogens have been detected in clinics and environments, while QACs were also reported to induce the formation of bacterial persisters. Even worse, the resistant bacteria even showed co-resistance and cross-resistance with traditional antibiotics, decreasing therapeutic effectiveness, and disrupting the microecology homeostasis. Unfortunately, the resistance and persistence mechanisms of QACs and the effects of QACs on microecology are still not clear, which even neglected during their daily usages. Therefore, we summarized and discussed current understandings on the antimicrobial actions, resistance, persistence and impacts on the microecology to highlight the challenges in the QACs applications and discuss the possible strategies for overcoming their drawbacks.

Virucidal Coatings Active Against SARS-CoV-2

Three types of coatings (contact-based, release-based, and combined coatings with both contact-based and release-based actions) were prepared and tested for the ability to inactivate SARS-CoV-2. In these coatings, quaternary ammonium surfactants were used as active agents since quaternary ammonium compounds are some of the most commonly used disinfectants. To provide contact-based action, the glass and silicon surfaces with covalently attached quaternary ammonium cationic surfactant were prepared using a dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride modifier. Surface modification was confirmed by attenuated total reflection infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and contact angle measurements. The grafting density of the modifier was estimated by XPS and elemental analysis. To provide release-based action, the widely used quaternary ammonium cationic disinfectant, benzalkonium chloride (BAC), and a newly synthesized cationic gemini surfactant, C18-4-C18, were bound non-covalently to the surface either through hydrophobic or electrostatic interactions. Virus titration revealed that the surfaces with combined contact-based and release-based action and the surfaces with only release-based action completely inactivate SARS-CoV-2. Coatings containing only covalently bound disinfectant are much less effective; they only provide up to 1.25 log10 reduction in the virus titer, probably because of the low disinfectant content in the surface monolayer. No pronounced differences in the activity between the flat and structured surfaces were observed for any of the coatings under study. Comparative studies of free and electrostatically bound disinfectants show that binding to the surface of nanoparticles diminishes the activity. These data indicate that SARS-CoV-2 is more sensitive to the free disinfectants.

Synthesis and broad-spectrum biocidal effect of novel gemini quaternary ammonium compounds

Since the discovery of antimicrobial agents, the misuse of antibiotics has led to the emergence of bacterial strains resistant to both antibiotics and common disinfectants like quaternary ammonium compounds (QACs). A new class, 'gemini' QACs, which contain two polar heads, has shown promise. Octenidine (OCT), a representative of this group, is effective against resistant microorganisms but has limitations such as low solubility and high cytotoxicity. In this study, we developed 16 novel OCT derivatives. These compounds were subjected to in silico screening to predict their membrane permeation. Testing against nosocomial bacterial strains (G+ and G-) and their biofilms revealed that most compounds were highly effective against G+ bacteria, while compounds 7, 8, and 10-12 were effective against G- bacteria. Notably, compounds 6-8 were significantly more effective than OCT and BAC standards across the bacterial panel. Compound 12 stood out due to its low cytotoxicity and broad-spectrum antimicrobial activity, comparable to OCT. It also demonstrated impressive antifungal activity. Compound 1 was highly selective to fungi and four times more effective than OCT without its cytotoxicity. Several compounds, including 4, 6, 8, 9, 10, and 12, showed strong virucidal activity against murine cytomegalovirus and herpes simplex virus 1. In conclusion, these gemini QACs, especially compound 12, offer a promising alternative to current disinfectants, addressing emerging resistances with their enhanced antimicrobial, antifungal, and virucidal properties.

Mechanisms of action of microbicides commonly used in infection prevention and control

SUMMARYUnderstanding how commonly used chemical microbicides affect pathogenic microorganisms is important for formulation of microbicides. This review focuses on the mechanism(s) of action of chemical microbicides commonly used in infection prevention and control. Contrary to the typical site-specific mode of action of antibiotics, microbicides often act via multiple targets, causing rapid and irreversible damage to microbes. In the case of viruses, the envelope or protein capsid is usually the primary structural target, resulting in loss of envelope integrity or denaturation of proteins in the capsid, causing loss of the receptor-binding domain for host cell receptors, and/or breakdown of other viral proteins or nucleic acids. However, for certain virucidal microbicides, the nucleic acid may be a significant site of action. The region of primary damage to the protein or nucleic acid is site-specific and may vary with the virus type. Due to their greater complexity and metabolism, bacteria and fungi offer more targets. The rapid and irreversible damage to microbes may result from solubilization of lipid components and denaturation of enzymes involved in the transport of nutrients. Formulation of microbicidal actives that attack multiple sites on microbes, or control of the pH, addition of preservatives or potentiators, and so on, can increase the spectrum of action against pathogens and reduce both the concentrations and times needed to achieve microbicidal activity against the target pathogens.

Ammonium chloride-induced hypothermia is attenuated by transient receptor potential channel vanilloid-1, but augmented by ankyrin-1 in rodents

AIMS

Systemic administration of ammonium chloride (NH4Cl), an acidifying agent used in human patients and experimental conditions, causes hypothermia in mice, however, the mechanisms of the thermoregulatory response to NH4Cl and whether it develops in other species remained unknown.

MAIN METHODS

We studied body temperature (Tb) changes in rats and mice induced by intraperitoneal administration of NH4Cl after blockade of transient receptor potential vanilloid-1 (TRPV1) or ankyrin-1 (TRPA1) channels.

KEY FINDINGS

In rats, NH4Cl decreased Tb by 0.4-0.8°C (p < 0.05). The NH4Cl-induced hypothermia also developed in Trpv1 knockout (Trpv1-/-) and wild-type (Trpv1+/+) mice, however, the Tb drop was exaggerated in Trpv1-/- mice compared to Trpv1+/+ controls with maximal decreases of 4.0 vs. 2.1°C, respectively (p < 0.05). Pharmacological blockade of TRPV1 channels with AMG 517 augmented the hypothermic response to NH4Cl in genetically unmodified mice and rats (p < 0.05 for both). In contrast, when NH4Cl was infused to mice genetically lacking the TRPA1 channel, the hypothermic response was significantly attenuated compared to wild-type controls with maximal mean Tb difference of 1.0°C between the genotypes (p = 0.008). Pretreatment of rats with a TRPA1 antagonist (A967079) also attenuated the NH4Cl-induced Tb drop with a maximal difference of 0.7°C between the pretreatment groups (p = 0.003).

SIGNIFICANCE

TRPV1 channels limit, whereas TRPA1 channels exaggerate the development of NH4Cl-induced hypothermia in rats and mice, but other mechanisms are also involved. Our results warrant for regular Tb control and careful consideration of NH4Cl treatment in patients with TRPA1 and TRPV1 channel dysfunctions.

Tetraalkylammonium salts (TAS) in solar energy applications - A review on in vitro and in vivo toxicity

Tetraalkylammonium salt (TAS) is an organic salt widely employed as a precursor, additive or electrolyte in solar cell applications, such as perovskite or dye-sensitized solar cells. Notably, Perovskite solar cells (PSCs) have garnered acclaim for their exceptional efficiency. However, PSCs have been associated with environmental and health concerns due to the presence of lead (Pb) content, the use of hazardous solvents, and the incorporation of TAS in their fabrication processes, which significantly contributes to environmental and human health toxicity. As a response, there is a growing trend towards transitioning to safer and biobased materials in PSC fabrication to address these concerns. However, the potential health hazards associated with TAS necessitate a thorough evaluation, considering the widespread use of this substance. Nevertheless, the overexploitation of TAS could potentially increase the disposal of TAS in the ecosystem, thus, posing a major health risk and severe pollution. Therefore, this review article presents a comprehensive discussion on the in vitro and in vivo toxicity assays of TAS as a potential material in solar energy applications, including cytotoxicity, genotoxicity, in vivo dermal, and systemic toxicity. In addition, this review emphasizes the toxicity of TAS compounds, particularly the linear tetraalkyl chain structures, and summarizes essential findings from past studies as a point of reference for the development of non-toxic and environmentally friendly TAS derivatives in future studies. The effects of the TAS alkyl chain length, polar head and hydrophobicity, cation and anion, and other properties are also included in this review.

A systematic overview of metal nanoparticles as alternative disinfectants for emerging SARS-CoV-2 variants

Coronaviruses are a diverse family of viruses, and new strains can emerge. While the majority of coronavirus strains cause mild respiratory illnesses, a few are responsible for severe diseases such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS). SARS-CoV-2, the virus responsible for COVID-19, is an example of a coronavirus that has led to a pandemic. Coronaviruses can mutate over time, potentially leading to the emergence of new variants. Some of these variants may have increased transmissibility or resistance to existing vaccines and treatments. The emergence of the COVID-19 pandemic in the recent past has sparked innovation in curbing virus spread, with sanitizers and disinfectants taking center stage. These essential tools hinder pathogen dissemination, especially for unvaccinated or rapidly mutating viruses. The World Health Organization supports the use of alcohol-based sanitizers and disinfectants globally against pandemics. However, there are ongoing concerns about their widespread usage and their potential impact on human health, animal well-being, and ecological equilibrium. In this ever-changing scenario, metal nanoparticles hold promise in combating a range of pathogens, including SARS-CoV-2, as well as other viruses such as norovirus, influenza, and HIV-1. This review explores their potential as non-alcoholic champions against SARS-CoV-2 and other pandemics of tomorrow. This extends beyond metal nanoparticles and advocates a balanced examination of pandemic control tools, exploring their strengths and weaknesses. The manuscript thus involves the evaluation of metal nanoparticle-based alternative approaches as hand sanitizers and disinfectants, providing a comprehensive perspective on this critical issue.

A Novel Handrub Tablet Loaded with Pre- and Post-Biotic Solid Lipid Nanoparticles Combining Virucidal Activity and Maintenance of the Skin Barrier and Microbiome

OBJECTIVE

This study aimed to develop a holobiont tablet with rapid dispersibility to provide regulation of the microbiota, virucidal activity, and skin barrier protection.

METHODS

A 23 factorial experiment was planned to define the best formulation for the development of the base tablet, using average weight, hardness, dimensions, swelling rate, and disintegration time as parameters to be analyzed. To produce holobiont tablets, the chosen base formulation was fabricated by direct compression of prebiotics, postbiotics, and excipients. The tablets also incorporated solid lipid nanoparticles containing postbiotics that were obtained by high-pressure homogenization and freeze-drying. The in vitro virucidal activity against alpha-coronavirus particles (CCoV-VR809) was determined in VERO cell culture. In vitro analysis, using monolayer cells and human equivalent skin, was performed by rRTq-PCR to determine the expression of interleukins 1, 6, 8, and 17, aquaporin-3, involucrin, filaggrin, FoxO3, and SIRT-1. Antioxidant activity and collagen-1 synthesis were also performed in fibroblast cells. Metagenomic analysis of the skin microbiome was determined in vivo before and after application of the holobiont tablet, during one week of continuous use, and compared to the use of alcohol gel. Samples were analyzed by sequencing the V3-V4 region of the 16S rRNA gene.

RESULTS

A handrub tablet with rapid dispersibility was developed for topical use and rinse off. After being defined as safe, the virucidal activity was found to be equal to or greater than that of 70% alcohol, with a reduction in interleukins and maintenance or improvement of skin barrier gene markers, in addition to the reestablishment of the skin microbiota after use.

CONCLUSIONS

The holobiont tablets were able to improve the genetic markers related to the skin barrier and also its microbiota, thereby being more favorable for use as a hand sanitizer than 70% alcohol.

A review on sterilization methods of environmental decontamination to prevent the coronavirus SARS-CoV-2 (COVID-19 virus): A new challenge towards eco-friendly solutions

In recent years, the COVID-19 pandemic is currently wreaking havoc on the planet. SARS-CoV-2, the Severe Acute Respiratory Syndrome Coronavirus, is the current term for this outbreak. Reports about this novel coronavirus have been presented since the pandemic's breakout, and they have demonstrated that it transmits rapidly from person to person, primarily by droplets in the air. Findings have illustrated that SARS-CoV-2 can survive on surfaces from hours to days. Therefore, it is essential to find practical solutions to reduce the virus's impact on human health and the environment. This work evaluated common sterilization methods that can decontaminate the environment and items. The goal is that healthcare facilities, disease prevention organizations, and local communities can overcome the new challenge of finding eco-friendly solutions. Further, a foundation of information encompassing various sterilization procedures and highlighting their limits to choose the most appropriate method to stop disease-causing viruses in the new context has been presented. The findings of this crucial investigation contribute to gaining insight into the comprehensive sterilization approaches against the coronavirus for human health protection and sustainable environmental development.

Learning from COVID-19: How drug hunters can prepare for the next pandemic

Over 3 years, the SARS-CoV-2 pandemic killed nearly 7 million people and infected more than 767 million globally. During this time, our very small company was able to contribute to antiviral drug discovery efforts through global collaborations with other researchers, which enabled the identification and repurposing of multiple molecules with activity against SARS-CoV-2 including pyronaridine tetraphosphate, tilorone, quinacrine, vandetanib, lumefantrine, cetylpyridinium chloride, raloxifene, carvedilol, olmutinib, dacomitinib, crizotinib, and bosutinib. We highlight some of the key findings from this experience of using different computational and experimental strategies, and detail some of the challenges and strategies for how we might better prepare for the next pandemic so that potential antiviral treatments are available for future outbreaks.

Determination of 25 quaternary ammonium compounds in sludge by liquid chromatography-mass spectrometry

With the pandemic of COVID-19, the application of quaternary ammonium compounds (QACs), which can be used in SARS-CoV-2 disinfection products, has increased substantially. QACs cumulated in sewer system are ultimately deposited and enriched in sludge. QACs in the environment can adversely affect human health and the environment. In this study, a liquid chromatography-mass spectrometry method was established for the simultaneous determination of 25 QACs in sludge samples. Ultrasonic extraction and filtration of the samples was performed using a 50 mM hydrochloric acid-methanol solution. The samples were separated by liquid chromatography and detected in multiple reaction monitoring mode. The matrix effects of the sludge on the 25 QACs ranged from - 25.5% to 7.2%. All substances showed good linearity in the range of 0.5-100 ng/mL, with all determination coefficients (R2) greater than 0.999. The method detection limits (MDLs) were 9.0 ng/g for alkyltrimethylammonium chloride (ATMAC), 3.0 ng/g for benzylalkyldimethylammonium chloride (BAC), and 3.0 ng/g for dialkyldimethylammonium chloride (DADMAC). The spiked recovery rates were in the range of 74-107%, while the relative standard deviations were in the range of 0.8-20.6%. Considering its sensitivity, accuracy, and easy operation, the proposed method in this study was used to determine 22 sludge samples collected from a comprehensive wastewater treatment plant. The results showed that the concentrations of ΣATMACs, ΣBACs, and ΣDADMACs were 19.684, 3.199, and 8.344 μg/g, respectively. The main components included ATMAC-C16, ATMAC-C18, ATMAC-C20, ATMAC-C22, BAC-C12, and DADMAC-C18:C18, with concentrations exceeding 1.0 μg/g. The concentration relationships of different components in the congeners showed that some components were of similar origin.

Discovery of PLpro and Mpro Inhibitors for SARS-CoV-2

There are very few small-molecule antivirals for SARS-CoV-2 that are either currently approved (or emergency authorized) in the US or globally, including remdesivir, molnupiravir, and paxlovid. The increasing number of SARS-CoV-2 variants that have appeared since the outbreak began over three years ago raises the need for continual development of updated vaccines and orally available antivirals in order to fully protect or treat the population. The viral main protease (Mpro) and the papain-like protease (PLpro) are key for viral replication; therefore, they represent valuable targets for antiviral therapy. We herein describe an in vitro screen performed using the 2560 compounds from the Microsource Spectrum library against Mpro and PLpro in an attempt to identify additional small-molecule hits that could be repurposed for SARS-CoV-2. We subsequently identified 2 hits for Mpro and 8 hits for PLpro. One of these hits was the quaternary ammonium compound cetylpyridinium chloride with dual activity (IC50 = 2.72 ± 0.09 μM for PLpro and IC50 = 7.25 ± 0.15 μM for Mpro). A second inhibitor of PLpro was the selective estrogen receptor modulator raloxifene (IC50 = 3.28 ± 0.29 μM for PLpro and IC50 = 42.8 ± 6.7 μM for Mpro). We additionally tested several kinase inhibitors and identified olmutinib (IC50 = 0.54 ± 0.04 μM), bosutinib (IC50 = 4.23 ± 0.28 μM), crizotinib (IC50 = 3.81 ± 0.04 μM), and dacominitinib (IC50 = IC50 3.33 ± 0.06 μM) as PLpro inhibitors for the first time. In some cases, these molecules have also been tested by others for antiviral activity for this virus, or we have used Calu-3 cells infected with SARS-CoV-2. The results suggest that approved drugs can be identified with promising activity against these proteases, and in several cases we or others have validated their antiviral activity. The additional identification of known kinase inhibitors as molecules targeting PLpro may provide new repurposing opportunities or starting points for chemical optimization.

Multicationic Quaternary Ammonium Compounds: A Framework for Combating Bacterial Resistance

During previous stages of research, high biocidal activity toward microorganism archival strains has been used as the main indicator in the development of new antiseptic formulations. Although this factor remains one of the most important characteristics of biocide efficiency, the scale of antimicrobial resistance spread causes serious concern. Therefore, focus shifts toward the development of formulations with a stable effect even in the case of prolonged contact with pathogens. Here, we introduce an original isocyanuric acid alkylation method with the use of available alkyl dichlorides, which opened access to a wide panel of multi-QACs with alkyl chains of various lengths between the nitrogen atoms of triazine and pyridine cycles. We used a complex approach for the resulting series of 17 compounds, including their antibiofilm properties, bacterial tolerance development, and antimicrobial activity toward multiresistant pathogenic strains. As a result of these efforts, available compounds have shown higher levels of antibacterial activity against ESKAPE pathogens than widely used commercial QACs. Hit compounds possessed high activity toward clinical bacterial strains and have also demonstrated a long-term biocidal effect without significant development of microorganism tolerance. The overall results indicated a high level of antibacterial activity and the broad application prospects of multi-QACs based on isocyanuric acid against multiresistant bacterial strains.

Pre-dental treatment screening in Indonesia during the COVID-19 pandemic: a questionnaire survey of dental practitioners

BACKGROUND

Dental practitioners have a high risk of contracting COVID-19 during the treatment of patients because of exposure to airborne droplets. However, the application of pre-procedure treatment screening in dental practices in Indonesia varied during the pandemic. The purpose of this study was to investigate the use of updated pre-procedure dental treatment protocols and procedures among dental practitioners in Indonesia.

METHODS

This study consisted of dentists registered as members of the Indonesian Dental Association who attended the Indonesian Dental Association webinar series in 2021. All the participants completed a questionnaire survey. The participants, who were from various regions in Indonesia, were granted password-protected access to a URL hosting the questionnaire. The questionnaire collected demographic information and contained questions on adherence to updated protocols and patient screening procedures, to which the respondents answered "Yes" or "No". For the analysis, the participants were divided into three groups based on the type of facility where they were employed: public (government) hospitals, private hospitals, or university hospitals (dental schools). A chi-square test was used to investigate the association between professional background and the implementation of updated protocols, including pre-procedure dental treatment screening. A value of P < 0.05 was considered statistically significant.

RESULTS

The age range of the participants was 20 - 60 years. The participants worked in facilities in 32 provinces in Indonesia. In total, there were 5,323 participants (males: n = 829; females: n = 4,494). In terms of professional backgrounds, 2,171, 2,867, and 285 participants were employed in government hospitals, private hospitals, and dental faculties, respectively. Among 5,232 participants who implemented updated COVID-19 prevention protocols, 5,053 (98%) participants performed pre-surgery procedures Among 151 participants who did not implement updated COVID-19 prevention protocols, 133 (88%) individuals carried out pre-rinse procedures.

CONCLUSIONS

Almost all the dental practitioners employed in government hospitals, private hospitals, and dental faculties in Indonesia performed pre-surgery patient screening procedures. There was an agreement between the dental professionals in all three settings on the need for COVID-19 pre-treatment screening procedures in dental practices during the COVID-19 pandemic.

Investigation of the impacts of simple electrolytes and hydrotrope on the interaction of ceftriaxone sodium with cetylpyridinium chloride at numerous study temperatures

Herein, interactions between cetylpyridinium chloride (CPC) and ceftriaxone sodium (CTS) were investigated applying conductivity technique. Impacts of the nature of additives (e.g. electrolytes or hydrotrope (HDT)), change of temperatures (from 298.15 to 323.15 K), and concentration variation of CTS/additives were assessed on the micellization of CPC + CTS mixture. The conductometric analysis of critical micelle concentration (CMC) with respect to the concentration reveals that the CMC values were increased with the increase in CTS concentration. In terms of using different mediums, CMC did not differ much with the increase in electrolyte salt (NaCl, Na2SO4) concentration, but increased significantly with the rise of HDT (NaBenz) amount. In the presence of electrolyte, CMC showed a gentle increment with temperature, while the HDT showed the opposite trend. Obtained result was further correlated with conventional thermodynamic relationship, where standard Gibb's free energy change ( Δ G m o ) , change of enthalpy ( Δ H m o ) , and change of entropy ( Δ S m o ) were utilized to investigate. The Δ G m o values were negative for all the mixed systems studied indicating that the micellization process was spontaneous. Finally, the stability of micellization was studied by estimating the intrinsic enthalpy gain (Δ H m o , ∗ ) and compensation temperature (Tc). Here, CPC + CTS mixed system showed more stability in Na2SO4 medium than the NaCl, while in NaBenz exhibited the lowest stability.

Mitigation of SARS-CoV-2 by Using Transition Metal Nanozeolites and Quaternary Ammonium Compounds as Antiviral Agents in Suspensions and Soft Fabric Materials

Introduction

The coronavirus disease 2019 (COVID-19) pandemic has demonstrated the need for novel, affordable, and efficient reagents to help reduce viral transmission, especially in high-risk environments including medical treatment facilities, close quarters, and austere settings. We examined transition-metal nanozeolite suspensions and quaternary ammonium compounds as an antiviral surface coating for various textile materials.

Methods

Zeolites are crystalline porous aluminosilicate materials, with the ability of ion-exchanging different cations. Nanozeolites (30 nm) were synthesized and then ion-exchanged with silver, zinc and copper ions. Benzalkonium nitrate (BZN) was examined as the quaternary ammonium ion (quat). Suspensions of these materials were tested for antiviral activity towards SARS-CoV-2 using plaque assay and immunostaining. Suspensions of the nanozeolite and quat were deposited on polyester and cotton fabrics and the ability of these textiles towards neutralizing SARS-CoV-2 was examined.

Results

We hypothesized that transition metal ion containing zeolites, particularly silver and zinc (AM30) and silver and copper (AV30), would be effective in reducing the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Additionally, AM30 and AV30 antiviral potency was tested when combined with a quaternary ammonium carrier, BZN. Our results indicate that exposure of SARS-CoV-2 to AM30 and/or AV30 suspensions reduced viral loads with time and exhibited dose-dependence. Antiviral activities of the combination of zeolite and BZN compositions were significantly enhanced. When used in textiles, AM30 and AV30-coated cotton and polyester fabrics alone or in combination with BZN exhibited significant antiviral properties, which were maintained even after various stress tests, including washes, SARS-CoV-2-repeated exposures, or treatments with soil-like materials.

Conclusion

This study shows the efficacy of transition metal nanozeolite formulations as novel antiviral agents and establishes that nanozeolite with silver and zinc ions (AM30) and nanozeolite with silver and copper ions (AV30) when combined with benzalkonium nitrate (BZN) quickly and continuously inactivate SARS-CoV-2 in suspension and on fabric materials.

Effect of surfactants on SARS-CoV-2: Molecular dynamics simulations

Surfactants are commonly used as disinfection agents in personal care products against bacteria and viruses, including SARS-CoV-2. However, there is a lack of understanding of the molecular mechanisms of the inactivation of viruses by surfactants. Here, we employ coarse grain (CG) and all-atom (AA) molecular dynamics simulations to investigate the interaction between general families of surfactants and the SARS-CoV-2 virus. To this end, we considered a CG model of a full virion. Overall, we found that surfactants have only a small impact on the virus envelope, being inserted into the envelope without dissolving it or generating pores, at the conditions considered here. However, we found that surfactants may induce a deep impact on the spike protein of the virus (responsible for its infectivity), easily covering it and inducing its collapse over the envelope surface of the virus. AA simulations confirmed that both negatively and positively charged surfactants are able to extensively adsorb over the spike protein and get inserted into the virus envelope. Our results suggest that the best strategy for the design of surfactants as virucidal agents will be to focus on those strongly interacting with the spike protein.

Quaternary ammonium compounds of emerging concern: Classification, occurrence, fate, toxicity and antimicrobial resistance

Amplified hygiene and precautionary measures are of utmost importance to control the spread of COVID-19 and future infection; however, these changes in practice are projected to trigger a rise in the purchase, utilisation and hence, discharge of many disinfectants into the environment. While alcohol-based, hydrogen peroxide-based, and chlorine-based compounds have been used widely, quaternary ammonium compounds (QACs) based disinfectants are of significant concern due to their overuse during this pandemic. This review presents the classification of disinfectants and their mechanism of action, focusing on QACs. Most importantly, the occurrence, fate, toxicity and antimicrobial resistance due to QACs are covered in this paper. Here we collated evidence from multiple studies and found rising trends of concern, including an increase in the mass load of QACs at a wastewater treatment plant (WWTP) by 331% compared to before the COVID-19 pandemic, as well as an increases in the concentration of 62% in residential dust, resulting in high concentrations of QACs in human blood and breast milk and suggesting that these could be potential sources of persistent QACs in infants. In addition to increased toxicity to human and aquatic life, increased use of QACs and accelerated use of antibiotics and antimicrobials during the COVID-19 pandemic could multiply the threat to antimicrobial resistance.

Study of Cationic Surfactants Raw Materials for COVID-19 Disinfecting Formulations by Potentiometric Surfactant Sensor

The behavior of a new 1,3-dioctadecyl-1H-imidazol-3-ium tetraphenylborate (DODI-TPB) surfactant sensor was studied in single and complex mixtures of technical grade QACs-benzalkonium chloride (BAC), N,N-didecyl-N,N-dimethylammonium chloride (DDAC), and N,N-dioctyl-N,N-dimethylammonium chloride (DOAC) usually used in COVID-19 disinfecting agents formulations. The results obtained with the new DODI-TPB sensor were in good agreement with data measured by a 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-tetraphenylborate (DMI-TPB) surfactant sensor, as well as two-phase titration used as a reference method. The quantitative titrations of a two-component mixture of the cationic homologs (a) DDAC and DOAC; and (b) BAC and DOAC showed that the new DODI-TPB surfactant sensor can clearly distinguish two separate mixture components in a single potentiometric titration curve with two characteristic inflexion points. The consumption of SDS (used as a titrant) in the end-point 1 (EP 1) corresponded to the content of DDAC (or BAC), whereas the consumption in the end-point 2 (EP 2) corresponded to the total content of both cationic surfactants in the mixture. DOAC content in both mixtures can be calculated from the difference of the titrant used to achieve EP1 and EP2. The addition of nonionic surfactants resulted in the signal change decrease from 333.2 mV (1:0; no nonionic surfactant added) to 243.0 mV (1:10, w/w). The sensor was successfully tested in ten two-component COVID-19 disinfecting formulations.

Efectividad de enjuagues bucales contra virus de la familia coronavirus

La aparición del virus Sars-CoV-2 y la enfermedad Covid-19 han provocado un estado de emergencia en el sistema de salud. Teniendo en cuenta el potencial de la saliva como material contaminante, la práctica odontológica fue una de las áreas que se vio afectada debido al uso de instrumentos que pueden esparcir aerosoles y salpicaduras que contienen microorganismos hacia el medio ambiente. Por esta razón, conociendo su potencial en la inactivación de patógenos, se propuso la utilización de enjuagues bucales en la práctica clínica previo a la realización de procedimientos dentales, sin embargo la evidencia no es clara respecto a su efectividad. Objetivo. Establecer el estado de evidencia actual del efecto de los enjuagues bucales sobre los coronavirus que se encuentran en cavidad. Métodos. Se realizó una revisión sistemática siguiendo todos los parámetros descritos en las DirectricesPRISMA basada en información obtenida en los buscadores Science direct, Pubmed y Dentistry and Oral Science Source. Los criterios de selección incluyeron estudios in vivo e in vitro de texto completo que evidenciaron la efectividad del enjuague bucal contra coronavirus. Resultados. Se obtuvieron 90 artículos, de los cuales sólo 12 cumplían con los criterios de inclusión,8 in vitro y 4 in vivo, que fueron sometidos a la evaluación de calidad metodológica utilizando la lista de verificación de evaluación crítica del JBI.  Conclusiones. Los resultados sugieren que la povidona yodada es efectiva para la inactivación del virus Sars-coV-2 en todas sus concentraciones.

Biomimetic Microadhesion Guided Instant Spinning

Animals create high-performance fibers at natural ambient conditions via a unique spinning process. In contrast, the spinning technologies developed by human beings are usually clumsy and require sophisticated skills. Here, inspired by adhesion-based silkworm spinning, we report a microadhesion guided (MAG) spinning technology for instant and on-demand fabrication of micro/nanofibers. Enabled by the adhesion between the spinning fluids and the microneedles, the MAG spinning can generate micro/nanofibers with programmable morphology. By further mimicking the head movement of the silkworm spinning, the MAG technology is extended with three different modes: straight, vibratory, and twisted spinning, which generate oriented fibers, hierarchical cross-linked fibers, and all-in-one fibers, respectively. Due to the prevalence of microadhesion and its unprecedented flexibility in operation, equipment-free MAG spinning is finally realized for instant fiber fabrication by only polymeric foams. Finally, the MAG spinning is demonstrated as a promising instant technology for emergent applications, such as wound dressing.

Virucidal activity and mechanism of action of cetylpyridinium chloride against SARS-CoV-2

Objective

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen causing the coronavirus disease 2019 (COVID-19) global pandemic. Recent studies have shown the importance of the throat and salivary glands as sites of virus replication and transmission. The viral host receptor, angiotensin-converting enzyme 2 (ACE2), is broadly enriched in epithelial cells of the salivary glands and oral mucosae. Oral care products containing cetylpyridinium chloride (CPC) as a bactericidal ingredient are known to exhibit antiviral activity against SARS-CoV-2 in vitro. However, the exact mechanism of action remains unknown.

Methods

This study examined the antiviral activity of CPC against SARS-CoV-2 and its inhibitory effect on the interaction between the viral spike (S) protein and ACE2 using an enzyme-linked immunosorbent assay.

Results

CPC (0.05%, 0.1% and 0.3%) effectively inactivated SARS-CoV-2 within the contact times (20 and 60 s) in directions for use of oral care products in vitro. The binding ability of both the S protein and ACE2 were reduced by CPC.

Conclusions

Our results suggest that CPC inhibits the interaction between S protein and ACE2, and thus, reduces infectivity of SARS-CoV-2 and suppresses viral adsorption.

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.

Broad-Spectrum Extracellular Antiviral Properties of Cucurbit[n]urils

Viruses are microscopic pathogens capable of causing disease and are responsible for a range of human mortalities and morbidities worldwide. They can be rendered harmless or destroyed with a range of antiviral chemical compounds. Cucurbit[n]urils (CB[n]s) are a family of macrocycle chemical compounds existing as a range of homologues; due to their structure, they can bind to biological materials, acting as supramolecular "hosts" to "guests", such as amino acids. Due to the increasing need for a nontoxic antiviral compound, we investigated whether cucurbit[n]urils could act in an antiviral manner. We have found that certain cucurbit[n]uril homologues do indeed have an antiviral effect against a range of viruses, including herpes simplex virus 2 (HSV-2), respiratory syncytial virus (RSV) and SARS-CoV-2. In particular, we demonstrate that CB[7] is the active homologue of CB[n], having an antiviral effect against enveloped and nonenveloped species. High levels of efficacy were observed with 5 min contact times across different viruses. We also demonstrate that CB[7] acts with an extracellular virucidal mode of action via host-guest supramolecular interactions between viral surface proteins and the CB[n] cavity, rather than via cell internalization or a virustatic mechanism. This finding demonstrates that CB[7] acts as a supramolecular virucidal antiviral (a mechanism distinct from other current extracellular antivirals), demonstrating the potential of supramolecular interactions for future antiviral disinfectants.

Decamethoxin virucidal activity: in vitro and in silico studies

The data on the representative of decamethoxin short-term action on infectious bronchitis virus (IBV) strain H120 used as a human-safe model of SARS-CoV-2 virus are presented. The viral activity was estimated with the use of inverted microscope PrimoVert (Germany) by destructive effect on BHK21 fibroblastic cell line. In vitro results demonstrated that decamethoxin (100 μg/ml) completely inactivated IBV coronavirus strain at exposure of 30 sec and more. At the lowest decamethoxin exposure of 10 sec the antiseptic virucidal activity was 33% and 36% of control at 24 and 48 h of cultivation respectively. Molecular docking analysis indicated the significant similarity of IBV and SARS-CoV-2 main protease (Mpro) structure. Docking studies of decamethoxin interaction with IBV Mpro and SARS-CoV-2 Mpro active centers demonstrated the ligand-protein complexes formation with the estimated binding energy of -8.6, -8.4 kcal/mol and key amino acid residues ASN26, GLY141, GLU187, GLU164, THR24, THR25, ASN142, GLY143, CYS145, HIS164 and GLU166. Keywords: decamethoxin, IBV strain H120, main protease, mole­cular docking, QAC, SARS-COV-2, virucidal activity

Disinfection Effect of Hexadecyl Pyridinium Chloride on SARS-CoV-2 in vitro

The novel coronavirus (COVID-19 or 2019-nCoV) is a respiratory virus that can exist in the mouth and saliva of patients and spreads through aerosol dispersion. Therefore, stomatological hospitals and departments have become high-infection-risk environments. Accordingly, oral disinfectants that can effectively inactivate the virus have become a highly active area of research. Hexadecyl pyridinium chloride, povidone-iodine, and other common oral disinfectants are the natural primary choices for stomatological hospitals. Therefore, this study investigated the inhibitory effect of hexadecyl pyridinium chloride on severe acute respiratory syndrome coronavirus (SARS-CoV-2) in vitro. Vero cells infected with SARS-CoV-2 were used to determine the disinfection effect; the CCK-8 method was used to determine cytotoxicity, and viral load was determined by real-time PCR. The results showed that hexadecyl pyridinium chloride has no obvious cytotoxic effect on Vero cells in the concentration range of 0.0125-0.05 mg/mL. The in vitro experiments showed that hexadecyl pyridinium chloride significantly inhibits the virus at concentrations of 0.1 mg/mL or above at 2 min of action. Thus, the results provide experimental support for the use of hexadecyl pyridinium chloride in stomatological hospitals.

Didecyldimethylammonium Chloride- and Polyhexamethylene Guanidine-Resistant Bacteria Isolated from Fecal Sludge and Their Potential Use in Biological Products for the Detoxification of Biocide-Contaminated Wastewater Prior to Conventional Biological Treatment

Simple Summary

Every year, more than a million tons of fecal sludge (FS) containing biocides based on quaternary ammonium compounds and guanidine derivatives, which are widely used for FS deodorization and control of microbial activity, are generated in the environmentally safe toilet complexes of Russian Railways trains. Higher disposal costs for such biocide-contaminated FS due to activated sludge toxicity increases pressure on sanitary equipment servicing companies («Ecotol Service» LLC) to more efficiently discharge FS to wastewater treatment plants. In this work, we have developed a new environmentally friendly approach to reducing the toxicity of FS, based on the use of biological products from biocide-resistant bacterial strains isolated from FS. Our approach has proven to be effective in a series of FS biodegradation experiments, biological oxygen demand tests, and a newly developed disk-diffusion bioassay.

Abstract

Toxic shock caused by the discharge of biocide-contaminated fecal sludge (FS) from chemical toilets to conventional wastewater treatment plants (WWTP) can be a major problem in activated sludge operation. It is necessary to develop new environmental approaches to mitigate the toxicity of biocides in order to avoid degrading the performance of WWTP. “Latrina”, a chemical toilet additive containing didecyldimethylammonium chloride and polyhexamethylene guanidine, is widely used in environmentally safe toilet complexes (ESTC) on Russian railway trains to deodorize FS and control microbial activity. In this work, seven biocide-resistant bacterial strains were isolated and identified from the FS of ESTC. The values of the minimum inhibitory and bactericidal concentrations of biocides for the isolated strains were 4.5–10 times higher than for the collection microorganisms. The bacterium Alcaligenes faecalis DOS7 was found to be particularly resistant to “Latrina”, the minimum inhibitory concentration of which was almost 30 times higher than recommended for ESTC. Biological products based on isolated bacterial strains proved to be effective for FS biodegradation under both aerobic and anaerobic conditions. The results of the biochemical oxygen demand test and the newly developed disk-diffusion bioassay confirmed that isolated strains contribute to reducing toxicity of biocidal agents in FS. Hyper-resistance, non-pathogenicity, and potential plant growth-promoting ability make A. faecalis DOS7 promising for use in various biological products for wastewater treatment and bioremediation of soils contaminated with biocides, as well as in agriculture to increase plant productivity.

Antiseptic Polymer-Surfactant Complexes with Long-Lasting Activity against SARS-CoV-2

Antiseptic polymer gel-surfactant complexes were prepared by incorporating the low-molecular-weight cationic disinfectant cetylpyridinium chloride into the oppositely charged, slightly cross-linked polymer matrices. Three types of polymers were used: copolymers of acrylamide and sodium 2-acrylamido-2-methylpropane sulfonate; copolymers of acrylamide and sodium methacrylate; copolymers of vinylpyrrolidone and sodium methacrylate. It was shown that the rate of the release of the cationic disinfectant from the oppositely charged polymer gels could be tuned in a fairly broad range by varying the concentration of the disinfectant, the degree of swelling, and degree of cross-linking of the gel and the content/type of anionic repeat units in the polymer matrix. Polymer-surfactant complexes were demonstrated to reduce SARS-CoV-2 titer by seven orders of magnitude in as little as 5 s. The complexes retained strong virucidal activity against SARS-CoV-2 for at least one week.

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.

Virucidal Activity of Over-the-Counter Oral Care Products Against SARS-CoV-2

PURPOSE

The oral cavity is an important entry point for SARS-CoV-2 infection. This study tested whether four commercially available mouthrinses and dentifrices have in vitro virucidal activity against SARS-CoV-2 (=4 log10 reduction in viral titer).

MATERIALS AND METHODS

One part of stock SARS-CoV-2 virus plus one part 0.3 g/l bovine serum albumin were mixed with eight parts of test product solution. After 30 s for the rinses, or 60 s for the dentifrices, the mixture was quenched in an appropriate neutralizer, serially diluted, and inoculated onto Vero E6 cells to determine viral titer. Triplicate runs were performed for each test condition with appropriate controls for test product cytotoxicity, viral interference, and neutralizer effectiveness. Test products included: 1.5% hydrogen peroxide (H2O2) rinse; 0.07% cetylpyridinium chloride (CPC) rinse; 0.454% stannous fluoride (SnF2) dentifrice A; and 0.454% SnF2 dentifrice B.

RESULTS

?The 1.5% H2O2 rinse, 0.07% CPC rinse, SnF2 dentifrice A, and SnF2 dentifrice B all produced > 4 log10 reduction in SARS-CoV-2 titer.

CONCLUSION

All four test products displayed potent virucidal activity in vitro. Clinical studies are warranted to determine what role, if any, these oral care products might play in preventing transmission of SARS-CoV-2 or in the management of patients currently diagnosed with COVID-19 illness.

Iron Phosphate Nanozyme-Hydrogel with Multienzyme-like Activity for Efficient Bacterial Sterilization

Pathogenic bacteria infections have posed a threat to human health worldwide. Nanomaterials with natural enzymatic activity provide an opportunity for the development of new antibacterial pathways. We successfully constructed iron phosphate nanozyme-hydrogel (FePO₄-HG) with the traits of positive charge and macropores. Interestingly, FePO₄-HG displayed not only peroxidase-like activity under acidic bacterial infectious microenvironment but also superoxide dismutase-catalase-like synergistic effects in neutral or weak alkaline conditions, thus protecting normal tissues from the peroxidase-like protocol with exogenous H₂O₂ damage. Furthermore, the positive charge and macropore structure of FePO₄-HG could capture and restrict bacteria in the range of ROS destruction. Obviously, FePO₄-HG exhibited excellent antibacterial ability against MRSA and AREC with the assistance of H₂O₂. Significantly, the FePO₄-HG + H₂O₂ system could efficiently disrupt the bacterial biofilm formation and facilitate the glutathione oxidation process to rapid bacterial death with low cytotoxicity. Moreover, FePO₄-HG was unsusceptible to bacterial resistance development in MRSA. Animal experiments showed that the FePO₄-HG + H₂O₂ group could efficiently eliminate the MRSA infection and present excellent wound healing without inflammation and tissue adhesions. With further development and optimization, FePO₄-HG has great potential as a new class of antibacterial agents to fight antibiotic-resistant pathogens.

Disinfectants role in the prevention of spreading the COVID ‐19 and other infectious diseases: The need for functional polymers!

The spreading of coronavirus through droplets and aerosols of an infected person is a well‐known mechanism. The main protection methods from this virus are using disinfectants/sanitizers, face masks, keeping social distance, and vaccination. With the rapid mutations of the virus accompanied by its features and contagions changing, new advanced functional materials development is highly needed. The usage of disinfectants/sanitizers in excess generates poisonous effects among the general public. Effective and simultaneously, human‐friendly sanitizers or disinfectants are required to prevent the poisoning and the associated issues. They minimize the toxic effects of the currently available materials by rapid action, high potential, long‐term stability, and excellent biocompatible nature. Here, we summarize the available antiviral materials, their features, and their limitations. We highlight the need to develop an arsenal of advanced functional antiviral polymers with intrinsic bioactive functionalities or released bioactive moieties in a controlled manner for rapid and long‐term actions for current and future anticipated viral outbreaks.

In vitro virucidal activity of mouthwashes on SARS‐CoV‐2

Objectives

Materials and Methods

Results

Conclusions

Cetylpyridinium chloride (CPC) reduces zebrafish mortality from influenza infection: Super-resolution microscopy reveals CPC interference with multiple protein interactions with phosphatidylinositol 4,5-bisphosphate in immune function

The COVID-19 pandemic raises significance for a potential influenza therapeutic compound, cetylpyridinium chloride (CPC), which has been extensively used in personal care products as a positively-charged quaternary ammonium antibacterial agent. CPC is currently in clinical trials to assess its effects on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) morbidity. Two published studies have provided mouse and human data indicating that CPC may alleviate influenza infection, and here we show that CPC (0.1 μM, 1 h) reduces zebrafish mortality and viral load following influenza infection. However, CPC mechanisms of action upon viral-host cell interaction are currently unknown. We have utilized super-resolution fluorescence photoactivation localization microscopy to probe the mode of CPC action. Reduction in density of influenza viral protein hemagglutinin (HA) clusters is known to reduce influenza infectivity: here, we show that CPC (at non-cytotoxic doses, 5-10 μM) reduces HA density and number of HA molecules per cluster within the plasma membrane of NIH-3T3 mouse fibroblasts. HA is known to colocalize with the negatively-charged mammalian lipid phosphatidylinositol 4,5-bisphosphate (PIP2); here, we show that nanoscale co-localization of HA with the PIP2-binding Pleckstrin homology (PH) reporter in the plasma membrane is diminished by CPC. CPC also dramatically displaces the PIP2-binding protein myristoylated alanine-rich C-kinase substrate (MARCKS) from the plasma membrane of rat RBL-2H3 mast cells; this disruption of PIP2 is correlated with inhibition of mast cell degranulation. Together, these findings offer a PIP2-focused mechanism underlying CPC disruption of influenza and suggest potential pharmacological use of this drug as an influenza therapeutic to reduce global deaths from viral disease.

Recent Advances and Mechanistic Insights into Antibacterial Activity, Antibiofilm Activity, and Cytotoxicity of Silver Nanoparticles

The substantial increase in multidrug-resistant (MDR) pathogenic bacteria is a major threat to global health. Recently, the Centers for Disease Control and Prevention reported possibilities of greater deaths due to bacterial infections than cancer. Nanomaterials, especially small-sized (size ≤10 nm) silver nanoparticles (AgNPs), can be employed to combat these deadly bacterial diseases. However, high reactivity, instability, susceptibility to fast oxidation, and cytotoxicity remain crucial shortcomings for their uptake and clinical application. In this review, we discuss various AgNPs-based approaches to eradicate bacterial infections and provide comprehensive mechanistic insights and recent advances in antibacterial activity, antibiofilm activity, and cytotoxicity (both in vitro and in vivo) of AgNPs. The mechanistic of antimicrobial activity involves four steps: (i) adhesion of AgNPs to cell wall/membrane and its disruption; (ii) intracellular penetration and damage; (iii) oxidative stress; and (iv) modulation of signal transduction pathways. Numerous factors affecting the bactericidal activity of AgNPs such as shape, size, crystallinity, pH, and surface coating/charge have also been described in detail. The review also sheds light on antimicrobial photodynamic therapy and the role of AgNPs versus Ag⁺ ions release in bactericidal activities. In addition, different methods of synthesis of AgNPs have been discussed in brief.

Efficacy of Pre-Procedural Mouthwashes against SARS-CoV-2: A Systematic Review of Randomized Controlled Trials

The oral mucosa is one of the first sites to be affected by the SARS-CoV-2. For this reason, healthcare providers performing aerosol-generating procedures (AGPs) in the oral cavity are at high risk of infection with COVID-19. The aim of this systematic review is to verify whether there is evidence in the literature describing a decrease in the salivary viral load of SARS-CoV-2 after using different mouthwashes. An electronic search of the MEDLINE database (via PubMed), Web of Science, SCOPUS, and the Cochrane library database was carried out. The criteria used were those described by the PRISMA® Statement. Randomized controlled trial studies that have used mouthwashes as a form of intervention to reduce the viral load in saliva were included. The risk of bias was analyzed using the Joanna Briggs Institute Critical Appraisal Tool. Ultimately, eight articles were included that met the established criteria. Based on the evidence currently available in the literature, PVP-I, CHX and CPC present significant virucidal activity against SARS-CoV-2 in saliva and could be used as pre-procedural mouthwashes to reduce the risk of cross-infection.

COVID-19 Drug Repurposing: A Network-Based Framework for Exploring Biomedical Literature and Clinical Trials for Possible Treatments

BACKGROUND

With the Coronavirus becoming a new reality of our world, global efforts continue to seek answers to many questions regarding the spread, variants, vaccinations, and medications. Particularly, with the emergence of several strains (e.g., Delta, Omicron), vaccines will need further development to offer complete protection against the new variants. It is critical to identify antiviral treatments while the development of vaccines continues. In this regard, the repurposing of already FDA-approved drugs remains a major effort. In this paper, we investigate the hypothesis that a combination of FDA-approved drugs may be considered as a candidate for COVID-19 treatment if (1) there exists an evidence in the COVID-19 biomedical literature that suggests such a combination, and (2) there is match in the clinical trials space that validates this drug combination.

METHODS

We present a computational framework that is designed for detecting drug combinations, using the following components (a) a Text-mining module: to extract drug names from the abstract section of the biomedical publications and the intervention/treatment sections of clinical trial records. (b) a network model constructed from the drug names and their associations, (c) a clique similarity algorithm to identify candidate drug treatments.

RESULT AND CONCLUSIONS

Our framework has identified treatments in the form of two, three, or four drug combinations (e.g., hydroxychloroquine, doxycycline, and azithromycin). The identifications of the various treatment candidates provided sufficient evidence that supports the trustworthiness of our hypothesis.

Virucidal Activity of Different Mouthwashes against the Salivary Load of SARS-CoV-2: A Narrative Review

The saliva of COVID-19-confirmed patients presents a high viral load of the virus. Aerosols generated during medical and dental procedures can transport the virus and are a possible causative agent of cross-infection. Since the onset of the pandemic, numerous investigations have been attempting to mitigate the risk of transmission by reducing the viral load in saliva using preprocedural mouthwashes. This study aims to review the most up-to-date in vitro and in vivo studies investigating the efficacy of different mouthwashes on reducing the salivary viral load of SARS-CoV-2, giving particular attention to the most recent randomized control trials published.

Evaluating the virucidal activity of four disinfectants against SARS-CoV-2

BACKGROUND

The recent COVID-19 pandemic highlights the need for efficacious virucidal products to limit the spread of SARS-CoV-2. Several studies have suggested that alcohol-based sanitizers and some disinfectants are effective. While virucidal activity data of low-level disinfectants are lacking and some conclusions are not clear yet.

METHODS

We evaluated the virucidal activity of 2 quaternary ammonium compounds (QAC) disinfectants (MICRO-CHEM PLUS and FWD), W30 (an amphoteric surfactant), and Medical EtOH against SARS-CoV-2. Suspension tests covering different concentration and contact time were performed using the integrated cell culture-qPCR method.

RESULTS

Each of disinfectants was effective at inactivating SARS-CoV-2. MCP and FWD are highly effective within 15 seconds. W30 is also efficient within 2 minutes at concentration of 1%. Consistent with previous report, our results also demonstrated that 38% ethanol was sufficient to completely inactivate virus, which proved the method used in this study is feasible.

CONCLUSIONS AND DISCUSSION

QAC disinfectants, MCP and FWD, are highly effective for the inactivation of SARS-CoV-2, which making them practical for use in health care setting and laboratories where prompt disinfection is important. The low-level disinfectant based on amphoteric surfactant, W30, which may present in commonly available household hygiene agents is also able to inactivate SARS-CoV-2.

Advances in the Prophylaxis of Respiratory Infections by the Nasal and the Oromucosal Route: Relevance to the Fight with the SARS-CoV-2 Pandemic

In this time of COVID-19 pandemic, the strategies for prevention of the infection are a primary concern. Looking more globally on the subject and acknowledging the high degree of misuse of protective face masks from the population, we focused this review on alternative pharmaceutical developments eligible for self-defense against respiratory infections. In particular, the attention herein is directed to the nasal and oromucosal formulations intended to boost the local immunity, neutralize or mechanically "trap" the pathogens at the site of entry (nose or mouth). The current work presents a critical review of the contemporary methods of immune- and chemoprophylaxis and their suitability and applicability in topical mucosal dosage forms for SARS-CoV-2 prophylaxis.

CPC-containing oral rinses inactivate SARS-CoV-2 variants and are active in the presence of human saliva

Introduction. The importance of human saliva in aerosol-based transmission of SARS-CoV-2 is now widely recognized. However, little is known about the efficacy of virucidal mouthwash formulations against emergent SARS-CoV-2 variants of concern and in the presence of saliva.

Hypothesis. Mouthwashes containing virucidal actives will have similar inactivation effects against multiple SARS-CoV-2 variants of concern and will retain efficacy in the presence of human saliva.

Aim. To examine in vitro efficacy of mouthwash formulations to inactivate SARS-CoV-2 variants.

Methodology. Inactivation of SARS-CoV-2 variants by mouthwash formulations in the presence or absence of human saliva was assayed using ASTM International Standard E1052-20 methodology.

Results. Appropriately formulated mouthwashes containing 0.07 % cetylpyridinium chloride but not 0.2 % chlorhexidine completely inactivated SARS-CoV-2 (USA-WA1/2020, Alpha, Beta, Gamma, Delta) up to the limit of detection in suspension assays. Tests using USA-WA1/2020 indicates that efficacy is maintained in the presence of human saliva.

Conclusions. Together these data suggest cetylpyridinium chloride-based mouthwashes are effective at inactivating SARS-CoV-2 variants. This indicates potential to reduce viral load in the oral cavity and mitigate transmission via salivary aerosols.

High-Throughput Chemical Screening and Structure-Based Models to Predict hERG Inhibition

Chemical inhibition of the human ether-a -go-go-related gene (hERG) potassium channel leads to a prolonged QT interval that can contribute to severe cardiotoxicity. The adverse effects of hERG inhibition are one of the principal causes of drug attrition in clinical and pre-clinical development. Preliminary studies have demonstrated that a wide range of environmental chemicals and toxicants may also inhibit the hERG channel and contribute to the pathophysiology of cardiovascular (CV) diseases. As part of the US federal Tox21 program, the National Center for Advancing Translational Science (NCATS) applied a quantitative high throughput screening (qHTS) approach to screen the Tox21 library of 10,000 compounds (~7871 unique chemicals) at 14 concentrations in triplicate to identify chemicals perturbing hERG activity in the U2OS cell line thallium flux assay platform. The qHTS cell-based thallium influx assay provided a robust and reliable dataset to evaluate the ability of thousands of drugs and environmental chemicals to inhibit hERG channel protein, and the use of chemical structure-based clustering and chemotype enrichment analysis facilitated the identification of molecular features that are likely responsible for the observed hERG activity. We employed several machine-learning approaches to develop QSAR prediction models for the assessment of hERG liabilities for drug-like and environmental chemicals. The training set was compiled by integrating hERG bioactivity data from the ChEMBL database with the Tox21 qHTS thallium flux assay data. The best results were obtained with the random forest method (~92.6% balanced accuracy). The data and scripts used to generate hERG prediction models are provided in an open-access format as key in vitro and in silico tools that can be applied in a translational toxicology pipeline for drug development and environmental chemical screening.

Influences of NaCl and Na2SO4 on the Micellization Behavior of the Mixture of Cetylpyridinium Chloride + Polyvinyl Pyrrolidone at Several Temperatures

Herein, the conductivity measurement technique is used to determine the interactions that may occur between polyvinyl pyrrolidone (PVP) polymer and cetylpyridinium chloride (CPC) surfactant in the presence of NaCl and Na2SO4 of fixed concentration at variable temperatures (298.15-323.15 K) with an interval of 5 K. In the absence or presence of salts, we observed three critical micelle concentrations (CMC) for the CPC + PVP mixture. In all situations, CMC1 values of CPC + PVP system were found to be higher in water than in attendance of salts (NaCl and Na2SO4). Temperature and additives have the tendency to affect counterion binding values. Various physico-chemical parameters were analyzed and demonstrated smoothly, including free energy (ΔG0m), enthalpy (ΔH0m) and entropy change (ΔS0m). The micellization process is achieved to be spontaneous based on the obtained negative ΔG0m values. The linearity of the ΔHmo and ΔSmo values is excellent. The intrinsic enthalpy gain (ΔH0*m) and compensation temperature (Tc) were calculated and discussed with logical points. Interactions of polymer hydrophobic chains or the polymer + surfactant associated with amphiphilic surface-active drugs can employ a strong impact on the behavior of the gels.

Virucidal Activity of Different Mouthwashes Using a Novel Biochemical Assay

BACKGROUND

Saliva of patients with COVID-19 has a high SARS-CoV-2 viral load. The risk of spreading the virus is not insignificant, and procedures for reducing viral loads in the oral cavity have been proposed. Little research to date has been performed on the effect of mouthwashes on the SARS-CoV-2 virus, and some of their mechanisms of action remain unknown.

METHODS

SARS-CoV-2 positive nasopharyngeal swabs measured by RT-PCR were used for virucidal activity in a 1:1 ratio, with an incubation time of 1 min. The solutions used in this study were: iodopovidone (8 mg); * D-limonene, a terpene extracted from citrus peels (0.3%); † cetylpyridinium chloride (0.1%) (CPC); ‡ chlorhexidine gluconate (10%) (CHX); § a CPC (0.12%) and CHX (0.05%) containing formula; ** a formula containing essential oils; †† a CPC containing formula (0.07%); ‡‡ a D-limonene (0.2%) and CPC (0.05%) containing formula; §§ a solution containing sodium fluoride (0.05%) and CPC (0.075%); *** a solution containing CHX (0.12%) and; ††† a CHX (0.2%) containing formula. ‡‡‡ As a control reaction, saline solution or excipient solution (water, glycerin, citric acid, colorant, sodium citrate) was used.

CONCLUSION

Within the limitations of this study, we can conclude that a mouthwash containing both D-limonene and CPC reduced the virucidal activity in about 6 logs (>99.999% reduction). Hence, establishing a clinical protocol for dentists is suggested, where all patients to be treated rinse pre-operatively with a mouthwash containing both D-limonene and CPC to reduce the likelihood of infection with SARS-CoV-2 for dentists. This is a relatively inexpensive way to reduce viral transmission of SARS-CoV-2 from infected individuals within the community. It is also a simple way to decrease infections from asymptomatic and pre-symptomatic patients.

A Broad-Spectrum Antimicrobial and Antiviral Membrane Inactivates SARS-CoV-2 in Minutes

SARS-CoV-2, the virus that caused the COVID-19 pandemic, can remain viable and infectious on surfaces for days, posing a potential risk for fomite transmission. Liquid-based disinfectants, such as chlorine-based ones, have played an indispensable role in decontaminating surfaces but they do not provide prolonged protection from recontamination. Here a safe, inexpensive, and scalable membrane with covalently immobilized chlorine, large surface area, and fast wetting that exhibits long-lasting, exceptional killing efficacy against a broad spectrum of bacteria and viruses is reported. The membrane achieves a more than 6 log reduction within several minutes against all five bacterial strains tested, including gram-positive, gram-negative, and drug-resistant ones as well as a clinical bacterial cocktail. The membrane also efficiently deactivated nonenveloped and enveloped viruses in minutes. In particular, a 5.17 log reduction is achieved against SARS-CoV-2 after only 10 min of contact with the membrane. This membrane may be used on high-touch surfaces in healthcare and other public facilities or in air filters and personal protective equipment to provide continuous protection and minimize transmission risks.

Real-Time Analysis of Antiproliferative Effects of Mouthwashes Containing Alcohol, Sodium Fluoride, Cetylpyridinium Chloride, and Chlorhexidine In Vitro

Objectives

In this study, the cytotoxic responses of six different over-the-counter mouthwashes on L929 cells were analyzed by two different techniques: the traditional colorimetric tetrazolium-based reduction assay (MTT) and the modern impedance-based real-time cell analysis (RTCA) system to investigate their biocompatibility in vitro. Thus, the investigation of the antiproliferative effects of the specified materials via different techniques is vital to reach this goal.

Materials and Methods

First, L929 mouse fibroblasts were exposed to the dilutions of mouthwashes for 2 minutes. After incubation, the tetrazolium reduction method was used to assess the metabolic viability of cells measured by colorimetric MTT assay and morphological inspection of cells was performed via phase-contrast microscopy. Furthermore, the effect of each mouthwash on the proliferation, morphology, and adhesion of L929 cells was monitored continuously by a noninvasive and label-free RTCA system for 140 h.

Results

Our data showed that all of the mouthwashes had varying cytotoxic effects on fibroblasts compared to the control group in MTT assay. In addition to that, RTCA technology has provided the growth kinetic profiles that can be used to analyze if the treatment is causing antimitotic or DNA-damaging effect on cells. Thus, analysis via this system can tell us the mechanism of toxicity behind the cell growth inhibition in vitro. Here, we found that only mouthwash 1 moderately maintained the viability of the L929 cells, yet displaying antimitotic effects and the other mouthwashes (mouthwash 2-mouthwash 6) showed toxicity via DNA-damaging effects.

Conclusions

Of the six types of mouthwash tested, the most biocompatible result was obtained from a mouthwash containing alcohol (i.e., mouthwash 1). On the other hand, sodium fluoride- (NaF-) and cetylpyridinium chloride- (CPC-) containing mouthwash (i.e., mouthwash 2) showed the most cytotoxic effect.

The effectiveness of various gargle formulations and salt water against SARS-CoV-2

The COVID-19 is difficult to contain due to its high transmissibility rate and a long incubation period of 5 to 14 days. Moreover, more than half of the infected patients were young and asymptomatic. Virus transmission through asymptomatic patients is a major challenge to disease containment. Due to limited treatment options, preventive measures play major role in controlling the disease spread. Gargling with antiseptic formulation may have potential role in eliminating the virus in the throat. Four commercially available mouthwash/gargle formulations were tested for virucidal activity against SARS-CoV-2 in both clean (0.3 g/l BSA) and dirty (0.3 g/l BSA + 3 mL/L human erythrocytes) conditions at time points 30 and 60 s. The virus was isolated and propagated in Vero E6 cells. The cytotoxicity of the products to the Vero E6 was evaluated by kill time assay based on the European Standard EN14476:2013/FprA1:2015 protocol. Virus titres were calculated as 50% tissue culture infectious dose (TCID50/mL) using the Spearman-Karber method. A reduction in virus titer of 4 log₁₀ corresponds to an inactivation of ≥ 99.99%. Formulations with cetylperidinium chloride, chlorhexidine and hexitidine achieved > 4 log10 reduction in viral titres when exposed within 30 s under both clean and dirty conditions. Thymol formulations achieved only 0.5 log₁₀ reduction in viral titres. In addition, salt water was not proven effective. Gargle formulations with cetylperidinium chloride, chlorhexidine and hexetidine have great potential in reducing SAR-CoV-2 at the source of entry into the body, thus minimizing risk of transmission of COVID-19.