A case of Magnusiomyces capitatus isolated during monitoring in an antimicrobial diagnostic stewardship context.

Magnusiomyces capitatus (M. capitatus) is an emerging opportunistic yeast in the Mediterranean region typically isolated from immunocompromised patients, usually affected by blood malignancies. We reported a rare case of M. capitatus infection, isolated from a drainage fluid in a patient affected by lung cancer recovered in the University Hospital of Campania "Luigi Vanvitelli", Naples, Italy. The isolate was identified by phenotypic methods, i.e., Gram and Lactophenol cotton blue (LCB) staining, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. We identified M. capitatus on the third day from Sabouraud Dextrose Agar supplemented with chloramphenicol and gentamicin. Antifungal susceptibility test revealed that 5-fluorocytosine was the most active drug against M. capitatus, followed by itraconazole and voriconazole, micafungin, amphotericin B and fluconazole, posaconazole, anidulafungin, and caspofungin. Our data showed the importance of an early cultural and fast microbiology diagnosis based on the characteristic morphologic features observed in Gram-stained smears of blood culture positive bottles, and the validation via MALDI-TOF MS. This dual approach has significant impact in the clinical management of infectious diseases and antibiotic stewardship, by integrating sample processing, fluid handling, and detection for rapid bacterial diagnosis.

Cistus incanus: a natural source of antimicrobial metabolites.

The discovery of natural molecules with antimicrobial properties has become an urgent need for the global treatment of bacterium and virus infections. Cistus incanus, a Mediterranean shrub species, represents a valuable source of phytochemicals with an interesting wide-spectrum antimicrobial potential. In this study, we analysed the spectrum of molecules composing a commercial hydroalcoholic extract of C. incanus finding ellagitannins as the most abundant. The effect of the extract and its main constituents (gallic acid, ellagic acid and punicalin) was assessed as co-treatment during viral (HSV-1, HCoV-229E, SARS-CoV-2) and bacterial infection (Staphylococcus aureus and Escherichia coli) of cells and as pre-treatment before virus infections. The results indicated a remarkable antiviral activity of punicalin against SARS-CoV-2 by pre-treating both the viral and the host cells, and a major sensitivity of S. aureus to the C. incanus extract compared to E. coli. The present study highlights broad antimicrobial potential of C. incanus extract.

Ligand-Free Silver Nanoparticles: An Innovative Strategy against Viruses and Bacteria.

The spread of antibiotic-resistant bacteria and the rise of emerging and re-emerging viruses in recent years constitute significant public health problems. Therefore, it is necessary to develop new antimicrobial strategies to overcome these challenges. Herein, we describe an innovative method to synthesize ligand-free silver nanoparticles by Pulsed Laser Ablation in Liquid (PLAL-AgNPs). Thus produced, nanoparticles were characterized by total X-ray fluorescence, zeta potential analysis, transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to evaluate the nanoparticles' cytotoxicity. Their potential was evaluated against the enveloped herpes simplex virus type 1 (HSV-1) and the naked poliovirus type 1 (PV-1) by plaque reduction assays and confirmed by real-time PCR and fluorescence microscopy, showing that nanoparticles interfered with the early stage of infection. Their action was also examined against different bacteria. We observed that the PLAL-AgNPs exerted a strong effect against both methicillin-resistant Staphylococcus aureus (S. aureus MRSA) and Escherichia coli (E. coli) producing extended-spectrum ß-lactamase (ESBL). In detail, the PLAL-AgNPs exhibited a bacteriostatic action against S. aureus and a bactericidal activity against E. coli. Finally, we proved that the PLAL-AgNPs were able to inhibit/degrade the biofilm of S. aureus and E. coli.

Oreoch-1: A broad-spectrum virus and host-targeting peptide against animal infections.

In recent decades, the global rise of viral emerging infectious diseases has posed a substantial threat to both human and animal health worldwide. The rapid spread and accumulation of mutations into viruses, and the limited availability of antiviral drugs and vaccines, stress the urgent need for alternative therapeutic strategies. Antimicrobial peptides (AMPs) derived from natural sources present a promising avenue due to their specificity and effectiveness against a broad spectrum of pathogens. The present study focuses on investigating the antiviral potential of oreochromicin-1 (oreoch-1), a fish-derived AMP obtained from Nile tilapia, against a wide panel of animal viruses including canine distemper virus (CDV), Schmallenberg virus (SBV), caprine herpesvirus 1 (CpHV-1), and bovine herpesvirus 1 (BoHV-1). Oreoch-1 exhibited a strong antiviral effect, demonstrating an inhibition of infection at concentrations in the micromolar range. The mechanism of action involves the interference with viral entry into host cells and a direct interaction between oreoch-1 and the viral envelope. In addition, we observed that the peptide could also interact with the cell during the CDV infection. These findings not only highlight the efficacy of oreoch-1 in inhibiting viral infection but also emphasize the potential of fish-derived peptides, specifically oreoch-1, as effective antiviral agents against viral infections affecting animals, whose potential to spill into humans is high. This research contributes valuable insights to the ongoing quest for novel antiviral drugs with the potential to mitigate the impact of infectious diseases on a global scale.

Antibacterial applications of biologically synthesized Pichia pastoris silver nanoparticles.

Objectives: This article highlights the biological synthesis of silver nanoparticles (AgNPs) with their characteristic analysis, and it focuses on the application of synthesized NPs against multidrug resistance (MDR) bacteria. A cytotoxicity study was performed to assess the biocompatibility. Methods: Silver nanoparticle (AgNPs) formation was confirmed by different characterization methods such as UV-Vis spectrophotometer, Dynamic light scattering (DLS)- Zeta, Fourier transform infrared (FTIR), and Transmission electron microscope (TEM). The antimicrobial activity of the AgNPs was checked against various bacterial strains of Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Enterococcus faecalis (E. faecalis), and Klebsiella pneumonia (K. pneumonia) by disc diffusion, minimum inhibition concentration test (MIC), and kinetic studies. The cytotoxicity of NPs against the Vero cell line was studied by cytotoxic assay. Results: The primary analysis of the formation of nanoparticles (NPs) was made by UV-Vis spectrophotometric analysis at 400 nm. At the same time, the efficient capping checked by FTIR shows the presence of a functional group at different wavelengths 3284, 1641,1573,1388,1288, and 1068 cm-1. At the same time, the transmission electron microscopic analysis (TEM) and DLS show that the shape and size of the synthesized NPs possess an average size of around ∼10-30 nm with spherical morphology. Further, the zeta potential confirmed the stability of the NPs. While the yield of NPs formation from silver salt was determined by an online yield calculator with the EDX analysis results. Synthesized NPs showed bactericidal effects against all the selected MDR pathogens with nontoxic effects against mammalian cells. Conclusion: Our findings indicate the remarkable antimicrobial activity of the biologically synthesized AgNPs, which can be an antimicrobial agent against multi-drug-resistant bacteria.

Nanoparticles and Their Antibacterial Application in Endodontics.

Root canal treatment represents a significant challenge as current cleaning and disinfection methodologies fail to remove persistent bacterial biofilms within the intricate anatomical structures. Recently, the field of nanotechnology has emerged as a promising frontier with numerous biomedical applications. Among the most notable contributions of nanotechnology are nanoparticles, which possess antimicrobial, antifungal, and antiviral properties. Nanoparticles cause the destructuring of bacterial walls, increasing the permeability of the cell membrane, stimulating the generation of reactive oxygen species, and interrupting the replication of deoxyribonucleic acid through the controlled release of ions. Thus, they could revolutionize endodontics, obtaining superior results and guaranteeing a promising short- and long-term prognosis. Therefore, chitosan, silver, graphene, poly(lactic) co-glycolic acid, bioactive glass, mesoporous calcium silicate, hydroxyapatite, zirconia, glucose oxidase magnetic, copper, and zinc oxide nanoparticles in endodontic therapy have been investigated in the present review. The diversified antimicrobial mechanisms of action, the numerous applications, and the high degree of clinical safety could encourage the scientific community to adopt nanoparticles as potential drugs for the treatment of endodontic diseases, overcoming the limitations related to antibiotic resistance and eradication of the biofilm.

SARS-CoV-2 Fusion Peptide Conjugated to a Tetravalent Dendrimer Selectively Inhibits Viral Infection.

Fusion is a key event for enveloped viruses, through which viral and cell membranes come into close contact. This event is mediated by viral fusion proteins, which are divided into three structural and functional classes. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein belongs to class I fusion proteins, characterized by a trimer of helical hairpins and an internal fusion peptide (FP), which is exposed once fusion occurs. Many efforts have been directed at finding antivirals capable of interfering with the fusion mechanism, mainly by designing peptides on the two heptad-repeat regions present in class I viral fusion proteins. Here, we aimed to evaluate the anti-SARS-CoV-2 activity of the FP sequence conjugated to a tetravalent dendrimer through a classical organic nucleophilic substitution reaction (SN2) using a synthetic bromoacetylated peptide mimicking the FP and a branched scaffold of poly-L-Lysine functionalized with cysteine residues. We found that the FP peptide conjugated to the dendrimer, unlike the monomeric FP sequence, has virucidal activity by impairing the attachment of SARS-CoV-2 to cells. Furthermore, we found that the peptide dendrimer does not have the same effects on other coronaviruses, demonstrating that it is selective against SARS-CoV-2.

Antiviral activity of nitazoxanide against Morbillivirus infections.

The measles virus (MeV) and canine distemper virus (CDV) belong to the genus Morbillivirus of the Paramyxoviridae family. They are enveloped viruses harboring a non-segmented negative-sense RNA. Morbilliviruses are extremely contagious and transmitted through infectious aerosol droplets. Both MeV and CDV may cause respiratory infections and fatal encephalitis, although a high incidence of brain infections is unique to CDV. Despite the availability of a safe and effective vaccine against these viruses, in recent years we are witnessing a strong resurgence of Morbillivirus infection. Measles still kills more than 100,000 people each year, and CDV causes widespread outbreaks, especially among wild animals, including non-human primates. No drugs are currently approved for MeV and CDV. Therefore, the identification of effective antiviral agents represents an unmet medical need. Here, we have investigated the potential antiviral properties of nitazoxanide (NTZ) against MeV and CDV. Antiviral activity was explored with live virus and cell-based assays. NTZ is a thiazolide that is approved by the FDA as an antiprotozoal agent for the treatment of Giardia intestinalis and Cryptosporidium parvum. Further, nitazoxanide and its metabolite tizoxanide have recently emerged as broad-spectrum antiviral agents. We found that NTZ blocks the MeV and CDV replication, acting at the post-entry level. Moreover, we showed that NTZ affects the function of the viral fusion protein (F), impairing viral spread. Our results indicate that NTZ should be further explored as a therapeutic option in measles and canine distemper virus treatment.

Melittin-Related Peptides Interfere with Sandfly Fever Naples Virus Infection by Interacting with Heparan Sulphate.

Emerging viruses pose an important global public health challenge, and early action is needed to control their spread. The Bunyaviridae family contains a great number of arboviruses which are potentially pathogenic for humans. For example, phleboviruses affect a large range of hosts, including humans and animals. Some infections usually have an asymptomatic course, but others lead to severe complications, such as Toscana virus, which is able to cause meningitis and encephalitis. Unfortunately, to date, no vaccines or antiviral treatments have been found. In the present study, we evaluated the effect of melittin-related peptides, namely the frog-derived RV-23 and AR-23, on sandfly fever Naples virus infection in vitro. Both peptides exhibited a strong antiviral activity by targeting the viral particles and blocking the virus-cell interaction. Their action was directed to an early phase of SFNV infection, in particular at viral adsorption on host cells, by interfering with the binding of common glycosaminoglycan receptors. Given the better antimicrobial behavior of AR-23 and RV-23 compared to melittin in terms of selectivity, our studies expand our understanding of the potential of these peptides as antimicrobials and stimulate further investigations in the direction of novel antiviral strategies against phlebovirus infection.

Oreoch-1: A Peptide from Oreochromis niloticus as a Potential Tool against Staphylococci.

Staphylococci, including Staphylococcus aureus and Staphylococcus epidermidis, are important human pathogens associated with potentially life-threatening infections. Their great biofilm-producing ability and the development of resistance mechanisms often account for therapeutic failure. Hence, the scientific community has devoted intensive efforts to the development of antimicrobial compounds active against both planktonic and sessile bacterial populations. Contextually, antimicrobial peptides (AMPs) are natural peptides produced by the innate immunity of every organism, representing a potential new therapeutic solution against human microbial pathogens. Our work focused on the in vitro activity of Oreoch-1, an AMP from the gills of Nile tilapia (Oreochromis niloticus), against standard and clinical S. aureus and S. epidermidis strains. Firstly, the cytotoxicity profile of Oreoch-1 was determined in human colon carcinoma cells. Secondly, its antibacterial spectrum was explored against staphylococcal strains to set up the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Our results highlighted an antibacterial activity in the range 6.25-25 µM, with a general bacteriostatic effect. Therefore, the biofilm-inhibitory property was assessed against S. aureus ATCC 25923 and S. epidermidis ATCC 35984, indicating a significant reduction in S. aureus biomass at sub-MIC concentrations. Overall, our study indicates Oreoch-1 as a promising new therapeutic weapon against staphylococcal infections.

Cupferron impairs the growth and virulence of Escherichia coli clinical isolates.

AIMS: Multidrug resistance is a worrying problem worldwide. The lack of readily available drugs to counter nosocomial infections requires the need for new interventional strategies. Drug repurposing represents a valid alternative to using commercial molecules as antimicrobial agents in a short time and with low costs. Contextually, the present study focused on the antibacterial potential of the ammonium salt N-nitroso-N-phenylhydroxylamine (Cupferron), evaluating the ability to inhibit microbial growth and influence the main virulence factors. METHODS AND RESULTS: Cupferron cytotoxicity was checked via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and hemolysis assays. The antimicrobial activity was assessed through the Kirby-Bauer disk diffusion test, broth microdilution method, and time-killing kinetics. Furthermore, the impact on different stages of the biofilm life cycle, catalase, swimming, and swarming motility was estimated via MTT and crystal violet (CV) assay, H2O2 sensitivity, and motility tests, respectively. Cupferron exhibited <15% cytotoxicity at 200 µg/mL concentration. The 90% bacterial growth inhibitory concentrations (MIC90) values recorded after 24 hours of exposure were 200 and 100 µg/mL for multidrug-resistant (MDR) and sensitive strains, respectively, exerting a bacteriostatic action. Cupferron-treated bacteria showed increased susceptibility to biofilm production, oxidative stress, and impaired bacterial motility in a dose-dependent manner. CONCLUSIONS: In the new antimicrobial compounds active research scenario, the results indicated that Cupferron could be an interesting candidate for tackling Escherichia coli infections.

Hylin-a1: A Pan-Inhibitor against Emerging and Re-Emerging Respiratory Viruses.

Pandemic and epidemic outbreaks of respiratory viruses are a challenge for public health and social care system worldwide, leading to high mortality and morbidity among the human populations. In light of the limited efficacy of current vaccines and antiviral drugs against respiratory viral infections and the emergence and re-emergence of new viruses, novel broad-spectrum antiviral drugs are needed for the prevention and treatment of these infections. Antimicrobial peptides with an antiviral effect, also known as AVPs, have already been reported as potent inhibitors of viral infections by affecting different stages of the virus lifecycle. In the present study, we analyzed the activity of the AVP Hylin-a1, secreted by the frog Hypsiboas albopunctatus, against a wide range of respiratory viruses, including the coronaviruses HCoV-229E and SARS-CoV-2, measles virus, human parainfluenza virus type 3, and influenza virus H1N1. We report a significant inhibitory effect on infectivity in all the enveloped viruses, whereas there was a lack of activity against the naked coxsackievirus B3. Considering the enormous therapeutic potential of Hylin-a1, further experiments are required to elucidate its mechanism of action and to increase its stability by modifying the native sequence.

Repurposing Selamectin as an Antimicrobial Drug against Hospital-Acquired Staphylococcus aureus Infections.

The emergence of multidrug-resistant strains requires the urgent discovery of new antibacterial drugs. In this context, an antibacterial screening of a subset of anthelmintic avermectins against gram-positive and gram-negative strains was performed. Selamectin completely inhibited bacterial growth at 6.3 µg/mL concentrations against reference gram-positive strains, while no antibacterial activity was found against gram-negative strains up to the highest concentration tested of 50 µg/mL. Given its relevance as a community and hospital pathogen, further studies have been performed on selamectin activity against Staphylococcus aureus (S. aureus), using clinical isolates with different antibiotic resistance profiles and a reference biofilm-producing strain. Antibacterial studies have been extensive on clinical S. aureus isolates with different antibiotic resistance profiles. Mean MIC90 values of 6.2 µg/mL were reported for all tested S. aureus strains, except for the macrolide-resistant isolate with constitutive macrolide-lincosamide-streptogramin B resistance phenotype (MIC90 9.9 µg/mL). Scanning Electron Microscopy (SEM) showed that selamectin exposure caused relevant cell surface alterations. A synergistic effect was observed between ampicillin and selamectin, dictated by an FIC value of 0.5 against methicillin-resistant strain. Drug administration at MIC concentration reduced the intracellular bacterial load by 81.3%. The effect on preformed biofilm was investigated via crystal violet and confocal laser scanning microscopy. Selamectin reduced the biofilm biomass in a dose-dependent manner with minimal biofilm eradication concentrations inducing a 50% eradication (MBEC50) at 5.89 µg/mL. The cytotoxic tests indicated that selamectin exhibited no relevant hemolytic and cytotoxic activity at active concentrations. These data suggest that selamectin may represent a timely and promising macrocyclic lactone for the treatment of S. aureus infections.

Synthetic Frog-Derived-like Peptides: A New Weapon against Emerging and Potential Zoonotic Viruses.

Given the emergence of the coronavirus disease 2019 (COVID-19), zoonoses have raised in the spotlight of the scientific community. Animals have a pivotal role not only for this infection, but also for many other recent emerging and re-emerging viral diseases, where they may represent both intermediate hosts and/or vectors for zoonoses diffusion. Today, roughly two-thirds of human infections are derived from animal origins; therefore, the search for new broad-spectrum antiviral molecules is mandatory to prevent, control and eradicate future epidemic outbreaks. Host defense peptides, derived from skin secretions of amphibians, appear as the right alternative to common antimicrobial drugs. They are cationic peptides with an amphipathic nature widely described as antibacterial agents, but less is reported about their antiviral potential. In the present study, we evaluated the activity of five amphibian peptides, namely RV-23, AR-23, Hylin-a1, Deserticolin-1 and Hylaseptin-P1, against a wide panel of enveloped animal viruses. A strong virucidal effect was observed for RV-23, AR-23 and Hylin-a1 against bovine and caprine herpesviruses, canine distemper virus, bovine viral diarrhea virus, and Schmallenberg virus. Our results identified these three peptides as potential antiviral-led candidates with a putative therapeutic effect against several animal viruses.

New Imidazolium Alkaloids with Broad Spectrum of Action from the Marine Bacterium Shewanella aquimarina.

The continuous outbreak of drug-resistant bacterial and viral infections imposes the need to search for new drug candidates. Natural products from marine bacteria still inspire the design of pharmaceuticals. Indeed, marine bacteria have unique metabolic flexibility to inhabit each ecological niche, thus expanding their biosynthetic ability to assemble unprecedented molecules. The One-Strain-Many-Compounds approach and tandem mass spectrometry allowed the discovery of a Shewanella aquimarina strain as a source of novel imidazolium alkaloids via molecular networking. The alkaloid mixture was shown to exert bioactivities such as: (a) antibacterial activity against antibiotic-resistant Staphylococcus aureus clinical isolates at 100 µg/mL, (b) synergistic effects with tigecycline and linezolid, (c) restoration of MRSA sensitivity to fosfomycin, and (d) interference with the biofilm formation of S. aureus 6538 and MRSA. Moreover, the mixture showed antiviral activity against viruses with and without envelopes. Indeed, it inhibited the entry of coronavirus HcoV-229E and herpes simplex viruses into human cells and inactivated poliovirus PV-1 in post-infection assay at 200 µg/mL. Finally, at the same concentration, the fraction showed anthelminthic activity against Caenorhabditis elegans, causing 99% mortality after 48 h. The broad-spectrum activities of these compounds are partially due to their biosurfactant behavior and make them promising candidates for breaking down drug-resistant infectious diseases.

Lavandula austroapennina: Assessment of the Antiviral Activity of Lipophilic Extracts from Its Organs.

In a framework aimed at the recovery and enhancement of medicinal plants endemic to the territory of the Cilento and Vallo di Diano National Park, Lavandula austroapennina N.G. Passal., Tundis and Upson has aroused interest. An insight into the chemical composition of the corolla, calyx, leaf, stem, and root organs was carried out following ultrasound-assisted maceration in n-hexane. The obtained lipophilic extracts were explored using ultra-high-performance chromatography coupled to high-resolution mass spectrometry (UHPLC-ESI-QqTOF-MS/MS). The extracts from the different organs varied in their relative content of fatty acids, ursanes, and oleanane-type triterpenes. In particular, the oleanolic acid content appeared to increase in the order of corolla < leaf < stem. An MTT assay was performed to verify the possible cytotoxicity of the organ extracts of L. austroapennina at a concentration ranging from 12.5 to 400 µg/mL on the Vero CCL-81 cell line. Antiviral activity against herpes simplex virus type 1 (HSV-1), alpha human coronavirus 229E (HCoV-229E), and poliovirus type 1 (PV-1) was evaluated via a plaque reduction assay in the same cellular model. All the extracts did not show cytotoxic effects after 2 and 24 h exposure times, and the antiviral efficacy was particularly important for the stem extract, capable of completely inhibiting the tested viruses at low doses. The antiviral activity in a non-enveloped virus PV-1 allowed the assertion that the extracts from the organs of L. austroapennina, and especially the stem extract, interfered directly with the viral envelope. This study underlines how much knowledge of a territory's medicinal plant heritage is a harbinger of promising discoveries in the health field.

Galdieria sulphuraria: An Extremophilic Alga as a Source of Antiviral Bioactive Compounds.

In the last decades, the interest in bioactive compounds derived from natural sources including bacteria, fungi, plants, and algae has significantly increased. It is well-known that aquatic or terrestrial organisms can produce, in special conditions, secondary metabolites with a wide range of biological properties, such as anticancer, antioxidant, anti-inflammatory, and antimicrobial activities. In this study, we focused on the extremophilic microalga Galdieria sulphuraria as a possible producer of bioactive compounds with antiviral activity. The algal culture was subjected to organic extraction with acetone. The cytotoxicity effect of the extract was evaluated by the 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The antiviral activity was assessed through a plaque assay against herpesviruses and coronaviruses as enveloped viruses and poliovirus as a naked one. The monolayer was treated with different concentrations of extract, ranging from 1 µg/mL to 200 µg/mL, and infected with viruses. The algal extract displayed strong antiviral activity at non-toxic concentrations against all tested enveloped viruses, in particular in the virus pre-treatment against HSV-2 and HCoV-229E, with IC50 values of 1.7 µg/mL and IC90 of 1.8 µg/mL, respectively. However, no activity against the non-enveloped poliovirus has been detected. The inhibitory effect of the algal extract was confirmed by the quantitative RT-PCR of viral genes. Preliminary chemical profiling of the extract was performed using ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS), revealing the enrichment in primary fatty acid amides (PFAA), such as oleamide, palmitamide, and pheophorbide A. These promising results pave the way for the further purification of the mixture to explore its potential role as an antiviral agent.

Antiherpetic Activity of Taurisolo®, a Grape Pomace Polyphenolic Extract.

Herpes simplex virus (HSV) is widespread in the population, causing oral or genital ulcers and, rarely, severe complications such as encephalitis, keratitis, and neonatal herpes. Current available anti-HSV drugs are acyclovir and its derivatives, although long-term therapy with these agents can lead to drug resistance. Thus, the discovery of novel antiherpetic compounds merits additional studies. In recent decades, much scientific effort has been invested in the discovery of new synthetic or natural compounds with promising antiviral properties. In our study, we tested the antiviral potential of a novel polyphenol-based nutraceutical formulation (named Taurisolo®) consisting of a water polyphenol extract of grape pomace. The evaluation of the antiviral activity was carried out by using HSV-1 and HSV-2 in plaque assay experiments to understand the mechanism of action of the extract. Results were confirmed by real-time PCR, transmission electron microscope (TEM), and fluorescence microscope. Taurisolo® was able to block the viral infection by acting on cells when added together with the virus and also when the virus was pretreated with the extract, demonstrating an inhibitory activity directed to the early phases of HSV-1 and HSV-2 infection. Altogether, these data evidence for the first time the potential use of Taurisolo® as a topical formulation for both preventing and healing herpes lesions.

Antiviral Peptides Delivered by Chitosan-Based Nanoparticles to Neutralize SARS-CoV-2 and HCoV-OC43.

The COVID-19 pandemic has made it clear that there is a crucial need for the design and development of antiviral agents that can efficiently reduce the fatality rate caused by infectious diseases. The fact that coronavirus mainly enters through the nasal epithelial cells and spreads through the nasal passage makes the nasal delivery of antiviral agents a promising strategy not only to reduce viral infection but also its transmission. Peptides are emerging as powerful candidates for antiviral treatments, showing not only a strong antiviral activity, but also improved safety, efficacy, and higher specificity against viral pathogens. Based on our previous experience on the use of chitosan-based nanoparticles to deliver peptides intra-nasally the current study aimed to explore the delivery of two-novel antiviral peptides making use of nanoparticles consisting of HA/CS and DS/CS. The antiviral peptides were chemically synthesized, and the optimal conditions for encapsulating them were selected through a combination of physical entrapment and chemical conjugation using HA/CS and DS/CS nanocomplexes. Finally, we evaluated the in vitro neutralization capacity against SARS-CoV-2 and HCoV-OC43 for potential use as prophylaxis or therapy.

Hylin-a1: A Host Defense Peptide with Antibacterial Potential against Staphylococcus aureus Multi-Resistant Strains.

In recent years, the resistance of pathogenic microorganisms to common antimicrobial agents has raised to a severe public health problem. The moderate and wise use of antimicrobials and the prevention of infections are the most effective strategies for decreasing the spread and development of resistance. Therefore, the World Health Organization (WHO) has intensified the search for new drugs to fight emerging pathogens. Antimicrobial peptides (AMPs), also known as host defense peptides (HDPs), play a crucial role in innate immunity, representing one of the first line of defense against microbial attacks. In this study, we evaluated the antibacterial activity of the AMP named Hylin-a1 (derived from the skin of the frog Heleioporus albopunctatus) against Staphylococcus aureus strains. S. aureus represents a commensal bacterium but also the principal causative agent of several human infections, including bacteremia, endocarditis, skin and device-related infections. Hylin-a1 toxicity was evaluated on human keratinocytes; once the non-cytotoxic concentration range was determined, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were analyzed, and time-killing assays were performed to verify the bacteriostatic and/or bactericidal activity of the peptide. We found that Hylin-a1 exerted a bacteriostatic action against most of the tested strains, with 90% inhibition at the concentration of 6.25 µM. Noteworthy, the peptide at a very low concentration (~3 µM) significantly blocked the growth of ß-lactam- and methicillin-resistant S. aureus. The levels of interleukin (IL)-1ß, IL-6 and IL-8 were quantified through a molecular assay, indicating that the peptide was able also to regulate the inflammatory response following bacterial infection. The effect of Hylin-a1 on S. aureus cell morphology was also evaluated. Altogether, these results indicate the high therapeutic potential of Hylin-a1 against a wide variety of clinical manifestations caused by S. aureus.