Evaluation Of Antiviral Activity Research Articles

Synthesis and Characterization of Chemically and Green-Synthesized Silver Oxide Particles for Evaluation of Antiviral and Anticancer Activity

Silver oxide (Ag2O) particles are wonderful candidates due to their unique properties, and their use in a wide range of research, industrial and biomedical applications is rapidly increasing. This makes it fundamental to develop simple, environmentally friendly methods with possible scaling. Herein, sodium borohydride and Datura innoxia leaf extract were applied as chemical and biological stabilizing and reducing agents to develop Ag2O particles. The primary aim was to evaluate the anticancer and antiviral activity of Ag2O particles prepared via two methods. XRD, UV-visible and SEM analyses were used to examine the crystallite structure, optical properties and morphology, respectively. The resulting green-synthesized Ag2O particles exhibited small size, spherically agglomerated shape, and high anticancer and antiviral activities compared to chemically synthesized Ag2O particles. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium-bromide) assay of green-synthesized Ag2O particles showed high anticancer activity against MCF-7 cells with IC50 = 17.908 µg/mL compared to chemically synthesized Ag2O particles with IC50 = 23.856 µg/mL. The antiviral activity of green-synthesized Ag2O particles and chemically synthesized Ag2O particles was also evaluated by a plaque-forming assay, and green-synthesized Ag2O particles showed higher antiviral ability with IC50 = 0.618 µg/mL as compared to chemically synthesized Ag2O particles with IC50 = 6.129 µg/mL. We propose the use of green-synthesized Ag2O particles in cancer treatment and drug delivery.

In vitro evaluation of antiviral activity in carnivorous plant species

In vitro evaluation of antiviral activity in carnivorous plant species

Antiviral activity evaluation and action mechanism of chalcone derivatives containing phenoxypyridine.

In this paper, a series of phenoxypyridine-containing chalcone derivatives (L1-L28) were designed and synthesized, characterized on NMR and HRMS. Ningnanmycin (NNM) was used as a control agent. The results of the antiviral activity testing showed that the curative activity EC50 values of L1 and L4 against TMV were 140.5 and 90.7μg/mL, respectively, which were superior to that of NNM (148.3μg/mL). The EC50 values of 154.1, 102.6 and 140.0μg/mL for the anti-TMV protective activities of L1, L4 and L15 were superior to that of NNM (188.2μg/mL). The mechanism of action between L4 and NNM and tobacco mosaic virus capsid protein (TMV-CP) was preliminarily investigated. The results of microscale thermophoresis (MST) experiments showed that L4 had a strong binding affinity for TMV-CP with a dissociation constant Kd value of 0.00149µM, which was better than that of NNM (2.73016µM). The results of molecular docking experiments showed that L4 formed shorter hydrogen bonds with amino acid residues of TMV-CP than NNM and formed more amino acid residues than NNM, which indicated that L4 was more tightly bound to TMV-CP. This study suggested that phenoxypyridine-containing chalcone derivatives can be used as new anti-TMV drugs through further research and development.

Evaluation of potential antiviral activities of antimicrobial peptides in fish mucus.

Fish skin mucus contains innate immune factors and acts as the first line of physical or chemical defense against pathogens. The primary aim of this study was to determine the antiviral activity of sea bream (SBr), rainbow trout (RT), and sea bass (SBa) fish skin mucus against herpes simplex virus (HSV)-1. In addition, it was aimed to associate possible antiviral activity with antimicrobial peptides (AMPs) such as cathelicidin, hepcidin, galectin 2, and C10ORF99, whose levels were determined in the mucus. The antiviral activity and oxidative/antioxidant status of mucus against HSV-1 virus was evaluated. In addition, AMPs, SOD, and CAT activities, and immunoglobulin M levels were also analyzed in mucus of fish. Antiviral activity mucus of SBr, RT, and SBa against HSV-1 were determined as 2-4 , 2-5 , and 2-2 , respectively. The higher antiviral activity of SBr and RT mucus compared to the mucus of SBa can be associated with higher AMP levels in them. The skin mucus of SBr and RT may be nutritional supplement, adjuvant, and a new agent that can potentiate the effects of antimicrobial/antiviral agents.

Identification and evaluation of antiviral activity of novel compounds targeting SARS-CoV-2 virus by enzymatic and antiviral assays, and computational analysis

The viral genome of the SARS-CoV-2 coronavirus, the aetiologic agent of COVID-19, encodes structural, non-structural, and accessory proteins. Most of these components undergo rapid genetic variations, though to a lesser extent the essential viral proteases. Consequently, the protease and/or deubiquitinase activities of the cysteine proteases Mpro and PLpro became attractive targets for the design of antiviral agents. Here, we develop and evaluate new bis(benzylidene)cyclohexanones (BBC) and identify potential antiviral compounds. Three compounds were found to be effective in reducing the SARS-CoV-2 load, with EC50 values in the low micromolar concentration range. However, these compounds also exhibited inhibitory activity IC50 against PLpro at approximately 10-fold higher micromolar concentrations. Although originally developed as PLpro inhibitors, the comparison between IC50 and EC50 of BBC indicates that the mechanism of their in vitro antiviral activity is probably not directly related to inhibition of viral cysteine proteases. In conclusion, our study has identified new potential noncytotoxic antiviral compounds suitable for in vivo testing and further improvement.

Evaluation of cytotoxicity and antiviral activity of Kyllinga nemoralis leaves and stems methanolic extract

This present study aimed to investigate the potential stems and leaves methanolic extract of Kyllinga nemoralis as an antiviral agent against Herpes Simplex Virus Type 1 (HSV-1). The leaves and stems of K. nemoralis methanolic extract were assessed in the cytotoxicity test using the MTT assays. The plaque reduction assay was evaluated in the post-treatment assay, pre-treatment assay, virucidal assay, time-addition test, and time-removal test. Cytotoxicity screening of stems and leaves of K. nemoralis against Vero cells shows that the cytotoxicity concentration of 50% of cell viability (CC50) values was 0.75 mg/mL, which indicates that K. nemoralis is non-cytotoxic and safe. The antiviral assay provides a Selective Index (SI) value (CC50/EC50) to determine the good SI for antiviral activity. In post-treatment, the SI value for this extract against HSV-1 was 8.33. In pre-treatment, the SI value for this extract was 21.43. In the virucidal test, the SI value for this extract was 24.19 mg/mL. In the time addition assay, the plaque inhibition reached 43% when the extract was added at 2 h.p.i, and it dropped to 15% at 10 h.p.i. In the time removal assay, the plaque inhibition reached 50% after the extract was removed at 2 h.p.i., and it increased to 87% at 24 h.p.i. This study showed that K. nemoralis has potential as a drug used to fight herpes infections.

ALVR106, an Off-the-Shelf, Multivirus-Specific T-Cell Therapy, for the Treatment of Respiratory Viral Infections: Results from a Phase 1, First-in-Human, Dose-Ranging Trial

Background: Community-acquired respiratory viruses such as influenza (Flu), human metapneumovirus (hMPV), parainfluenza virus (PIV), and respiratory syncytial virus (RSV) are leading causes of morbidity and mortality after hematopoietic cell transplant (HCT) or solid organ transplant (SOT). While these viruses may begin in the upper respiratory tract, ~50% of cases progress to the lower respiratory tract, potentially leading to more severe conditions such as pneumonia, bronchiolitis, bronchiolitis obliterans, and chronic lung allograft dysfunction. ALVR106 is an allogeneic, off-the-shelf, polyclonal, multi-respiratory virus T-cell therapy specific for Flu, hMPV, PIV, and RSV. ALVR106 is generated by exposing peripheral blood mononuclear cells to peptide mixtures followed by ex vivo expansion in presence of activating cytokines. The expanded T cells are Th1-polarized, polyfunctional, and selectively able to kill viral target cells. ALVR106 cells have not shown alloreactivity, attesting to their selectivity and safety for use in HCT or SOT. Methods: In this first-in-human, placebo (PBO)-controlled, dose-ranging trial, HCT or SOT recipients 17 years or older with upper or mild lower respiratory tract infections (URTI/LRTI) caused by Flu, hMPV, PIV, or RSV were randomized in a 3:1 ratio to receive ALVR106 or PBO. Four doses of ALVR106 ranging from 1 × 10 5 cells/kg to 2 × 10 6 cells/kg were planned to be given to 4 cohorts of 4 patients each. Patients receive up to 2 infusions of ALVR106 or PBO once every 14 days and will be followed for up to 1 year. The primary objective was safety as measured by treatment emergent adverse events (AEs), AEs of special interest (acute and chronic graft vs host disease (GvHD), cytokine release syndrome (CRS), infusion related reactions (IRR), and progressive dyspnea), and clinical laboratory abnormalities from baseline (BL) through 12 weeks after the last infusion. Secondary endpoints included evaluation of antiviral activity by qualitative PCR assay by nasal swab and a composite endpoint through D28 which included change from BL in Radiation Therapy Oncology Group Lung Toxicity Scale Grade and viral detection from nasal swab. Patients with an improvement in symptoms or undetectable virus were considered partial responders (PR); those with improved symptoms and undetectable virus were complete responders (CR), and those whose condition did not improve or worsen from BL were non-responders (NR). To assess functional T-cell immune reconstitution and frequency of circulating virus-specific T cells, IFN-g virus-specific ELISpot analysis was performed on serial blood samples over time. ELISpot results will be presented. Preliminary study results presented herein will be unblinded at the time of data presentation. Results: 16 patients were dosed: four in Cohorts (C) 1 and 2, five in C3, and three in C4. Table shows BL demographics, disease characteristics, and blinded results for safety and antiviral activity by composite endpoint. Cohorts 2, 3, and 4 had at least 1 patient with mild LRTI at BL, no patients in C1 had LRTI. All patients received at least 1 infusion. No patients with Flu were enrolled. In these blinded results, no differences were seen in rate or severity of AEs among cohorts. Four patients (25%) had AEs possibly related to treatment (ALVR106 or PBO); all were Grade 1 (mild) in severity. These related events were reported in 1 patient each: diarrhea, ear pressure, neutrophil count decrease, and 1 patient had pyrexia, cGvHD oral, and aGvHD skin. Eight patients (50%) had serious AEs (SAEs), none related to treatment. One patient (6%) in C3 had G2 progressive dyspnea not related to treatment. One patient (6%) in C1 had Grade I aGVHD skin and cGVHD oral; both were considered possibly related to treatment (ALVR106 or PBO). No patients had Grade II-IV aGVHD, cGVHD, IRR, or CRS. No clinically significant changes from BL or trends over time in lab abnormalities or vital signs were seen. At Day 28, all patients in C1 and C2 had undetectable respiratory virus via nasal swab, except 1 patient in C1 who missed D28 visit due to COVID-19; 4/5 (80%) in C3 were undetectable; and 2/3 (67%) in C4 were undetectable. Conclusion: In this ongoing trial-the first-in-human, double-blind, PBO-controlled trial of virus-specific T cell therapy in transplant recipients with respiratory infection-ALVR106 was safe and well tolerated, supporting its continued evaluation in HCT and SOT recipients.

Exploring the copper(II) coordination to 2′-hydroxy-4-benzyloxychalcone analogues and their potential pharmacological applications

Chalcones are chemical precursors of flavonoids and exhibit a variety of biological properties, including anti-cancer, anti-inflammatory, and anti-malarial activities. According to the literature, different transition metal complexes of chalcones exhibit antitumor and antibacterial properties. Herein we report the synthesis, characterization, and the in vitro evaluation of antileishmanial, antiproliferative, and antiviral activities of novel copper(II)-2′-hydroxy-4-benzyloxychalcone complexes. Two of the complexes (1 and 2) had the formula [Cu(L)2], and the other two (3 and 4) were characterized as [Cu(L)(phen)Cl], where L is the deprotonated form of the 2′-hydroxy-4-benzyloxychalcones (HL1, is a fluorine substituted analog of HL2) and phen is 1,10- phenanthroline. Structures resolved by single-crystal X-ray diffraction showed that complexes 3 and 4 had a distorted square pyramid geometry, with chloride at the apical position. The stability of the complexes in dimethyl sulfoxide showed a significant variation. A wide range of ligand exchange kinetics was observed in the solution, influenced by chalcone fluorination and the presence of phenanthroline. Potential pharmacological applications were evaluated using in vitro assays for anti-proliferative, leishmanicidal, and antiviral activities. Complexes 1 and 3 showed cytostatic effects against the human breast tumor cell line (MCF-7, GI50 = 4.6 and 1.0 µM, respectively) that could be attributed to the free ligand HL1 (MCF-7, GI50 = 1.16 µM). Moreover, complex 1 showed higher selectivity to MCF-7 cells in comparison to murine immortalized 3T3 cells (GI50 > 100 µM). Complex 2 was inactive and toxic while complex 4 showed an unspecific cytostatic effect. Despite a weak leishmanicidal activity, at 25 µM, complex 3 inhibited (85,1 %) the SARS-CoV-2 replication at 2 µM. As complex 4 also showed good antiviral activity against SARS-CoV-2 (84,7 %), the antiviral activity seems to be related to copper(II)-phenanthroline fragment. This work demonstrates how simple changes in the structure of the ligand affect ligand exchange reactions and, consequently biological activity. It also expands the biological applications of Cu(II) chalcone complexes.

Evaluation of Antiviral Activity of Ivermectin against Infectious Bovine Rhinotracheitis Virus in Rabbit Model.

Infectious bovine rhinotracheitis (IBR) caused by bovine herpes virus 1 (BoHV-1) can lead to enormous economic losses in the cattle industry. Vaccine immunization is preferentially used to decrease its transmission speed and resultant clinical signs, rather than to completely stop viral infection. Therefore, a drug effective in treating IBR is urgently needed. Our previous work demonstrated that ivermectin significantly inhibited viral replication in a cell infection model. This study aimed to investigate its antiviral effects in vivo by using a rabbit infection model. The viral inhibition assay was first used to confirm that ivermectin at low concentrations (6-25 nM) could reduce viral titers (TCID50) significantly (p < 0.001) at 24 h post-infection. In rabbits, ivermectin was administrated with one to three doses, based on the recommended anti-parasite treatment dosage (0.2 mg/kg bodyweight) through subcutaneous injection at different days post-infection in the treated IBRV infection groups, while non-treated infection group was used as the control. The infected rabbits showed hyperthermia and other clinical signs, but the number of high-fever rabbits in the ivermectin treatment groups was significantly lower than that in the non-treated infection group. Furthermore, in ivermectin treatment groups, the cumulative clinical scores correlated negatively with drug doses and positively with delay of administration time post-infection. The overall nasal shedding time in ivermectin-treated groups was two days shorter than the non-treated challenge group. At the same time point, the titer of neutralizing antibodies in the treatment group with triple doses was higher than the other two-dose groups, but the difference between the treatment groups decreased with the delay of drug administration. Correspondingly, the serious extent of lung lesions was negatively related to the dosage, but positively related to the delay of drug administration. The qPCR with tissue homogenates showed that the virus was present in both the lung tissues and trigeminals of the infected rabbits. In conclusion, ivermectin treatment had therapeutic effect by decreasing clinical signs and viral shedding, but could not stop virus proliferation in lung tissues and trigeminals.

Synthesis of novel rhodamine type Anthrone Spiro-lactam (ASL) analogues and evaluation of antiviral activity against dengue and chikungunya viruses

A series of Rhodamine type Anthrone-Spirolactam (ASL) derivatives Benzylimin-Anthrone-Spirolactam (ASL-1 to ASL-10) and Benzamide-Anthrone-Spirolactam (ASL-11 and ASL-12) were synthesized via a simple condensation reaction between Anthrone Spiro-lactamine (2) and various aromatic aldehyde and acyl chlorides respectively. Since rhodamine-based compounds were reported to have antiviral activity, the ASL derivatives were examined for in vitro antiviral activity against dengue and chikungunya viruses. Among all the analogues, ASL-3, ASL-6, ASL-7, ASL-8, ASL-9 and ASL-10 were the most potent against dengue virus (DENV) and exerted around one log reduction in virus titre under post-treatment conditions. At the same time ASL-3 was effective under co-treatment conditions. Two analogues ASL-6 and ASL-12 exerted anti-chikungunya virus (CHIKV) activity under post-treatment conditions. In silico docking studies revealed that the ASL derivatives interacted with the proteins of DENV and CHIKV. Together, the results suggest the anti-DENV and CHIKV activity of ASL derivatives which may be exploited further for therapeutic purposes.

In Vitro Evaluation of Antiviral Activities of Funicone-like Compounds Vermistatin and Penisimplicissin against Canine Coronavirus Infection.

Recent studies have demonstrated that 3-O-methylfunicone (OMF), a fungal secondary metabolite from Talaromyces pinophilus belonging to the class of funicone-like compounds, has antiviral activity against canine coronaviruses (CCoV), which causes enteritis in dogs. Herein, we selected two additional funicone-like compounds named vermistatin (VER) and penisimplicissin (PS) and investigated their inhibitory activity towards CCoV infection. Thus, both compounds have been tested for their cytotoxicity and for antiviral activity against CCoV in A72 cells, a fibrosarcoma cell line suitable for investigating CCoV. Our findings showed an increase in cell viability, with an improvement of morphological features in CCoV-infected cells at the non-toxic doses of 1 μM for VER and 0.5 μM for PS. In addition, we observed that these compounds caused a strong inhibition in the expression of the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor which is activated during CCoV infection. Our results also showed the alkalinization of lysosomes in the presence of VER or PS, which may be involved in the observed antiviral activities.

Synthesis of indole-based ferulic acid derivatives and in vitro evaluation of antiviral activity against SARS-CoV-2

Synthesis of indole-based ferulic acid derivatives and in vitro evaluation of antiviral activity against SARS-CoV-2

Synthesis, Cytotoxicity and Antiviral Activity Against Vaccinia Virus of 2-(3-Coumarinyl)-1-Hydroxyimidazoles.

In 1980, smallpox became the first viral disease eradicated through vaccination. After the termination of the Smallpox Eradication Program, the global immunization of the population also ceased. Now, most people do not have any immunity against infections caused by orthopoxviruses. Emerging cases of zoonotic orthopox infections transferring to humans inspire the search for new small organic molecules possessing antiviral activity against orthopoxviruses. Here, we present the synthesis and evaluation of antiviral activity against one of the orthopoxviruses, i.e., Vaccinia virus, of hybrid structures containing 1-hydroxyimidazole and benzopyranone moieties. Novel 2-(3-coumarinyl)-1-hydroxyimidazoles were synthesized. Their prototropic tautomerism was considered using 1H NMR spectroscopy. Antiviral activity of both new 2-(3-coumarinyl)- 1-hydroxyimidazoles and previously described 2-(3-chromenyl)-1-hydroxyimidazoles against Vaccinia virus was evaluated in Vero cell culture. Newly synthesized 2-(3-coumarinyl)-1-hydroxyimidazoles existed in CDCl3 as a mixture of prototropic tautomers (N-hydroxyimidazole and imidazole N-oxide), transition to DMSO-d6 resulting in the prevalence of N-oxide tautomer. Evaluation of cytotoxicity and antiviral activity against Vaccinia virus was performed in Vero cell culture. Compounds possessing high antiviral activity were present in both series. It was demonstrated that the structure of heterocyclic substituent in position 2 of imidazole impacted the cytotoxicity of substances under consideration. Thus, molecules containing coumarin moiety exhibited lower toxicity than similarly substituted 2-(3-chromenyl)-1- hydroxyimidazoles. Perspective virus inhibiting compounds possessing antiviral activity against Vaccinia virus were revealed in the series of 2-(3-coumarinyl)-1-hydroxyimidazoles.

Metabolomic profiling and biological evaluations of Spongia irregularis-associated actinomycetes supported by multivariate statistical analysis.

Metabolomics analysis using LC-HRESIMS of twelve extracts of Spongia irregularis associated actinomycetes for dereplication purposes in addition to evaluation of cytotoxic and antiviral activities of the extracts. In the present study, three actinomycetes belonging to the genera Micromonospora, Streptomyces, and Rhodococcus were recovered from the marine sponge Spongia irregularis. Applying OSMAC approach, each strain was fermented on four different media resulting in twelve extracts. All extracts were subjected to metabolomics analysis using LC-HRESIMS for dereplication purposes. Multivariate data statistical analysis was carried out for the differentiation between extracts. Additionally, the cytotoxic and anti-HCV potentials of extracts were evaluated. Most of extracts showed strong to moderate cytotoxicity effects against HepG-2, CACO-2 and MCF-7 cell lines with general IC50 range of 2.8-8.9µg/mL. Moreover, the extracts of Micromonospora sp. UR44 using ISP2 and OLIGO media and Streptomyces sp. UR32 using ISP2 medium exhibited anti-HCV activity with IC50 of 4.5±0.22, 3.8±0.18 and 5.7±0.15µM, respectively. Metabolomic analysis of twelve extracts of Spongia irregularis associated actinomycetes led to identification of large number of secondary metabolites. Morever, investigation of cytotoxic and antiviral activities of the extracts revealed that only three extracts exhibited antiviral activity and 7 extracts exhibited cytotoxic activity.

Phytochemical study of Euphorbia cyathophora collected in Dan Phuong, Hanoi and its antidengue activity against DENV1‐4 virus serotypes

AbstractThe ethanol extract from the leaves and twigs of Euphorbia cyathophora showed antiviral activity against four dengue virus serotypes (DENV1‐4), with PRNT50 values of 15.625‐62.5 μg/mL. Eight compounds including germanicol acetate (1), cymbopogone (2), 1‐heptacosanol (3), ethyl α‐L‐arabinofuranoside (4), quercetin (5), 3‐acetoxy‐5,7,3’,4’‐tetrahydroxyflavone (6), 3‐acetoxy‐5,7,4’‐trihydroxyflavone (7), 4’‐acetoxy‐3,5,7‐trihydroxyflavone (8) were isolated from this extract. Compounds 2‐8 were isolated for the first time from Euphorbia cyathophora. Antiviral activity evaluation of compounds 1‐3, 5‐7 on DENV1‐4 serotypes revealed that 7 was the most active compound with PRNT50 values of 23.8‐95.2 μM.

Synthesis, antiviral activity, and computational study of β-d-xylofuranosyl nucleoside phosphonates

Molecular dynamics (MD) simulations provided insights into the favorable interactions between xylose nucleosides bearing a phosphonate moiety at their 3′-position and specific residues at the active site of the archetypal RNA-dependent RNA-polymerase (RdRp) of Enterovirus 71. Therefore, a series of xylosyl nucleoside phosphonates with adenine, uracil, cytosine, guanosine, and hypoxanthine as nucleobases were synthesized through multistep sequences starting from a single common precursor. Following antiviral activity evaluation, the adenine containing analogue was found to possess good antiviral activity against RNA viruses displaying an EC50 of 12 and 16 μM against measles virus (MeV) and enterovirus-68 (EV-68), respectively, whereas lacking cytotoxicity.

Antiviral activity evaluation and action mechanism of myricetin derivatives containing thioether quinoline moiety.

A variety of myricetin derivatives containing thioether quinoline moiety were designed and synthesized. Their structures of title compounds were determined by 1H NMR, 13C NMR, 19F NMR, and HRMS. Single-crystal X-ray diffraction experiments were carried out with B4. Antiviral activity indicated that some of the target compounds exhibited remarkable anti-tobacco mosaic virus (TMV) activity. In particular, compound B6 possessed significant activity. The half maximal effective concentration (EC50) value of the curative activity of compound B6 was 169.0μg/mL, which was superior to the control agent ningnanmycin (227.2μg/mL). Meanwhile, the EC50 value of the protective activity of compound B6 was 86.5μg/mL, which was better than ningnanmycin (179.2μg/mL). Microscale thermophoresis (MST) indicated that compound B6 had a strong binding capability to the tobacco mosaic virus coat protein (TMV-CP) with a dissociation constant (Kd) value of 0.013μmol/L, which was superior to that of myricitrin (61.447μmol/L) and ningnanmycin (3.215μmol/L). And the molecular docking studies were consistent with the experimental results. Therefore, these novel myricetin derivatives containing thioether quinoline moiety could become potential alternative templates for novel antiviral agents.

In silico and in vitro evaluation of antiviral activity of wogonin against main protease of porcine epidemic diarrhea virus.

The high mortality rate of weaned piglets infected with porcine epidemic diarrhea virus (PEDV) poses a serious threat to the pig industry worldwide, demanding urgent research efforts related to developing effective antiviral drugs to prevent and treat PEDV infection. Small molecules can possibly prevent the spread of infection by targeting specific vital components of the pathogen's genome. Main protease (Mpro, also named 3CL protease) plays essential roles in PEDV replication and has emerged as a promising target for the inhibition of PEDV. In this study, wogonin exhibited antiviral activity against a PEDV variant isolate, interacting with the PEDV particles and inhibiting the internalization, replication and release of PEDV. The molecular docking model indicated that wogonin was firmly embedded in the groove of the active pocket of Mpro. Furthermore, the interaction between wogonin and Mpro was validated in silico via microscale thermophoresis and surface plasmon resonance analyses. In addition, the results of a fluorescence resonance energy transfer (FRET) assay indicated that wogonin exerted an inhibitory effect on Mpro. These findings provide useful insights into the antiviral activities of wogonin, which could support future research into anti-PEDV drugs.`.

Evaluation of Antiviral Activity of Gemcitabine Derivatives against Influenza Virus and Severe Acute Respiratory Syndrome Coronavirus 2.

Gemcitabine is a nucleoside analogue of deoxycytidine and has been reported to be a broad-spectrum antiviral agent against both DNA and RNA viruses. Screening of a nucleos(t)ide analogue-focused library identified gemcitabine and its derivatives (compounds 1, 2a, and 3a) blocking influenza virus infection. To improve their antiviral selectivity by reducing cytotoxicity, 14 additional derivatives were synthesized in which the pyridine rings of 2a and 3a were chemically modified. Structure-and-activity and structure-and-toxicity relationship studies demonstrated that compounds 2e and 2h were most potent against influenza A and B viruses but minimally cytotoxic. It is noteworthy that in contrast to cytotoxic gemcitabine, they inhibited viral infection with 90% effective concentrations of 14.5-34.3 and 11.4-15.9 μM, respectively, maintaining viability of mock-infected cells over 90% at 300 μM. Resulting antiviral selectivity was comparable to that of a clinically approved nucleoside analogue, favipiravir. The cell-based viral polymerase assay proved the mode-of-action of 2e and 2h targeting viral RNA replication and/or transcription. In a murine influenza A virus-infection model, intraperitoneal administration of 2h not only reduced viral RNA level in the lungs but also alleviated infection-mediated pulmonary infiltrates. In addition, it inhibited replication of severe acute respiratory syndrome virus 2 infection in human lung cells at subtoxic concentrations. The present study could provide a medicinal chemistry framework for the synthesis of a new class of viral polymerase inhibitors.

Piperazine-derived small molecules as potential Flaviviridae NS3 protease inhibitors. In vitro antiviral activity evaluation against Zika and Dengue viruses

Since 2011 Direct Acting antivirals (DAAs) drugs targeting different non-structural (NS) viral proteins (NS3, NS5A or NS5B inhibitors) have been approved for clinical use in HCV therapies. However, currently there are not licensed therapeutics to treat Flavivirus infections and the only licensed DENV vaccine, Dengvaxia, is restricted to patients with preexisting DENV immunity.Similarly to NS5 polymerase, the NS3 catalytic region is evolutionarily conserved among the Flaviviridae family sharing strong structural similarity with other proteases belonging to this family and therefore is an attractive target for the development of pan-flavivirus therapeutics.In this work we present a library of 34 piperazine-derived small molecules as potential Flaviviridae NS3 protease inhibitors. The library was developed through a privileged structures-based design and then biologically screened using a live virus phenotypic assay to determine the half-maximal inhibitor concentration (IC50) of each compound against ZIKV and DENV. Two lead compounds, 42 and 44, with promising broad-spectrum activity against ZIKV (IC50 6.6 µM and 1.9 µM respectively) and DENV (IC50 6.7 µM and 1.4 µM respectively) and a good security profile were identified. Besides, molecular docking calculations were performed to provide insights about key interactions with residues in NS3 proteases’ active sites.