Antiviral Activity Research Articles

Sustained antiviral response against in vitro HIV-1 infection in peripheral blood mononuclear cells from people with chronic myeloid leukemia treated with ponatinib.

HIV-1 infection cannot be cured due to long-lived viral reservoirs formed by latently infected CD4+ T cells. "Shock and Kill" strategy has been considered to eliminate the viral reservoir and achieve a functional cure but the stimulation of cytotoxic immunity is necessary. Ponatinib is a tyrosine kinase inhibitor (TKI) clinically used against chronic myeloid leukemia (CML) that has demonstrated to be effective against HIV-1 infection in vitro. Several TKIs may induce a potent cytotoxic response against cancer cells that makes possible to discontinue treatment in people with CML who present long-term deep molecular response. In this longitudinal study, we analyzed the capacity of ponatinib to induce an antiviral response against HIV-1 infection in peripheral blood mononuclear cells (PBMCs) obtained from people with CML previously treated with imatinib for a median of 10years who changed to ponatinib for 12months to boost the anticancer response before discontinuing any TKI as part of the clinical trial NCT04043676. Participants were followed-up for an additional 12months in the absence of treatment. PBMCs were obtained at different time points and then infected in vitro with HIV-1. The rate of infection was determined by quantifying the intracellular levels of p24-gag in CD4+ T cells. The levels of p24-gag+ CD4+ T-cells were lower when these cells were obtained during and after treatment with ponatinib in comparison with those obtained during treatment with imatinib. Cytotoxicity of PBMCs against HIV-infected target cells was significantly higher during treatment with ponatinib than during treatment with imatinib, and it was maintained at least 12months after discontinuation. There was a significant negative correlation between the lower levels of p24-gag+ CD4+ T-cells and the higher cytotoxicity induced by PBMCs when cells were obtained during and after treatment with ponatinib. This cytotoxic immunity was mostly based on higher levels of Natural Killer and Tγδ cells seemingly boosted by ponatinib. In conclusion, transient treatment with immunomodulators like ponatinib along with ART could be explored to boost the antiviral activity of cytotoxic cells and contribute to the elimination of HIV-1 reservoir.

The role of quercetin in NLRP3-associated inflammation.

Quercetin is a natural flavonoid that is widely found in fruits and vegetables. As an important flavonoid, it exhibits a wide range of biological activities, including antioxidant, anti-inflammatory, antiviral, immunomodulatory, and analgesic activities. Quercetin exerts powerful antioxidant activity by regulating glutathione, enzyme activity, and the production of reactive oxygen species (ROS). Quercetin exerts powerful anti-inflammatory effects by acting on the Nod-likereceptorprotein3 (NLRP3) inflammasome. In diabetes, quercetin has been shown to improve insulin sensitivity and reduce high blood sugar level, while, in neurological diseases, it potentially prevents neuronal degeneration and cognitive decline by regulating neuroinflammation. In addition, in liver diseases, quercetin may improve liver inflammation and fibrosis by regulating the NLRP3 activity. In addition, quercetin may improve inflammation in other diseases based on the NLRP3 inflammasome. With this background, in this review, we have discussed the progress in the study on the mechanism of quercetin toward improving inflammation via NLRP3 inflammasome in the past decade. In addition, from the perspective of quercetin glycoside derivatives, the anti-inflammatory mechanism of hyperoside, rutin, and isoquercetin based on NLRP3 inflammasome has been discussed. Moreover, we have discussed the pharmacokinetics of quercetin and its nanoformulation application, with the aim to provide new ideas for further research on the anti-inflammatory effect of quercetin and its glycoside derivatives based on NLRP3 inflammasome, as well as in drug development and application.

Synthesis and Anticancer Activity Assessment of Zelkovamycin Analogues.

The zelkovamycin family is a class of cyclic octapeptides with potent antibacterial and antiviral activity. Due to their unique chemical structures and excellent bioactivity, zelkovamycins have consistently attracted the interest of synthetic chemists. However, only the total synthesis of zelkovamycin and zelkovamycin G has been reported until now. The current work presents, for the first time, the synthesis of zelkovamycin analogues, along with their anticancer activity assessment. Firstly, the corresponding chain peptide based on the amino acid sequence of zelkovamycin H was synthesized using the Fmoc solid-phase peptide strategy. This was followed by cyclization under high dilution conditions to obtain compound 21, and its structure was elucidated by NMR analysis. The results confirm that compound 21 is not the natural product of zelkovamycin H. We deduced that during the synthesis of peptide 12, the D-Abu residue epimerized to the L-Abu form, leading to the formation of peptide 20, which blocked our efforts during the synthesis of zelkovamycin H. Two more analogues, 22 and 23, were synthesized by changing the structure of amino acid residues using the same strategy. The anticancer activity of analogues 21-23 against Huh-7 cells was evaluated in vitro; however, their IC50 values were >50 μM.

A Compressive Review on Source, Toxicity and Biological Activity of Flavonoid.

Flavonoids are biologically active chemicals in various fruits, plants, vegetables, and leaves, which have promising uses in medicinal science. The health properties of these natural chemicals are widely accepted, and efforts are underway to extract the specific components referred to as flavonoids. Flavonoids demonstrate a diverse range of bio-activities, anticancer, antioxidant activity, anti-cholinesterase activity, antiinflammatory activity, antimalarial activity, antidiabetic activity, neurodegenerative disease, cardiovascular effect, hepatoprotective effects, and antiviral and antimicrobial activity. This study aims to examine the prevailing trends in flavonoid investigation studies, elucidate the activity of flavonoids, examine their various functions and uses, assess the potential of flavonoids as preventive medications for chronic diseases, and outline future research opportunities in this field. This review explores the diverse functions of flavonoids in preventing and managing various diseases.

Design, Synthesis, Anti-TMV Activity, and Structure-Activity Relationships of Seco-pregnane C21 Steroids and Their Derivatives.

seco-pregnane C21 steroids exhibit high antiviral activity against the tobacco mosaic virus (TMV). However, the structural modification of seco-pregnane C21 steroids and the structure-activity relationship (SAR) of the modified compounds remain unevaluated. Hence, the present study investigated how variations in the original skeletons of natural seco-pregnane C21 steroids affect their antiviral activity. A series of glaucogenin C and A derivatives were designed and synthesized for the first time, and their anti-TMV activity was evaluated. Bioassay results showed that most of the newly designed derivatives exhibited good to excellent antiviral activity; among these derivatives, 5g, 5j, and 5l with higher antiviral activity than that of ningnanmycin emerged as new antiviral candidates. Reverse transcription-polymerase chain reaction and Western blotting assay revealed reduced levels of TMV coat protein (TMV-CP) gene transcription and TMV-CP protein expression, which confirmed the antiviral activity of these derivatives. These compounds also downregulated the expression of NtHsp70-1 and NtHsp70-061. Computational simulations indicated that 5l displayed strong van der Waals energy and electrostatic with the TMV coat protein, affording a lower binding energy (ΔGbind = -56.2 kcal/mol) compared with Ribavirin (ΔGbind = -47.6 kcal/mol). The SAR of these compounds was also evaluated, which demonstrated for the first time that substitutions at C-3 and double bonds of C-5/C-6 and C-13/C-18 are crucial for maintaining high anti-TMV activity.

Orally bioavailable RORγ/DHODH dual host-targeting small molecules with broad-spectrum antiviral activity

Host-directed antivirals (HDAs) represent an attractive treatment option and a strategy for pandemic preparedness, especially due to their potential broad-spectrum antiviral activity and high barrier to resistance development. Particularly, dual-targeting HDAs offer a promising approach for antiviral therapy by simultaneously disrupting multiple pathways essential for viral replication.Izumerogant (IMU-935) targets two host proteins, (i) the retinoic acid receptor-related orphan receptor γ isoform 1 (RORγ1), which modulates cellular cholesterol metabolism, and (ii) the enzyme dihydroorotate dehydrogenase (DHODH), which is involved in de novo pyrimidine synthesis. Here, we synthesized optimized derivatives of izumerogant and characterized their antiviral activity in comparison to a recently described structurally distinct RORγ/DHODH dual inhibitor. Cell culture-based infection models for enveloped and non-enveloped DNA and RNA viruses, as well as a retrovirus, demonstrated high potency and broad-spectrum activity against human viral pathogens for RORγ/DHODH dual inhibitors at nanomolar concentrations. Comparative analyses with equipotent single-target inhibitors in metabolite supplementation approaches revealed that the dual-targeting mode represents the mechanistic basis for the potent antiviral activity. For SARS-CoV-2, an optimized dual inhibitor completely blocked viral replication in human airway epithelial cells at 5 nM and displayed a synergistic drug interaction with the nucleoside analog molnupiravir. In a SARS-CoV-2 mouse model, treatment with a dual inhibitor alone, or in combination with molnupiravir, reduced the viral load by 7- and 58-fold, respectively.Considering the clinical safety, oral bioavailability, and tolerability of izumerogant in a recent Phase I study, izumerogant-like drugs represent potent dual-targeting antiviral HDAs with pronounced broad-spectrum activity for further clinical development.

Differing Transcriptomic Responses in High Titer versus Low Titer Aedes aegypti Mosquitoes after Oral Infection with Sindbis Virus.

Oral infection of mosquitoes by arboviruses often results in a large degree of variation in the amount of infectious virus between individual mosquitoes, even when the mosquitoes are from inbred laboratory strains. This variability in arbovirus load has been shown to affect virus transmissibility. Previously, our group described population genetic and specific infectivity differences between the virus populations found in high and low titer Aedes aegypti mosquitoes that had been orally infected with Sindbis virus (SINV). In this study, we sought to investigate whether there were also differences in transcriptomic response between these high and low titer mosquitoes. Results from the transcriptomic data analysis showed that more genes involved in antiviral activity, endopeptidase activity, and methyltransferase activity were upregulated in low titer mosquitoes than in high titer mosquitoes, relative to blood-fed controls. Meanwhile, genes involved in ion transport, energy metabolism, acetylation, glycosylation, lipid metabolism, and transport tended to be upregulated in high titer mosquitoes more than in low titer mosquitoes, relative to blood-fed mosquitoes. Overall, genes involved in antiviral activities tended to be upregulated in low titer mosquitoes while genes involved in proviral activities were mostly upregulated in high titer mosquitoes. This study has identified a number of candidate mosquito genes that are putatively associated with SINV titer variability after oral infection of Ae. aegypti, and these can now be investigated in order to ascertain their roles in virus replication and their contributions to determining vector competence.

Global remodeling of ADP-ribosylation by PARP1 suppresses influenza A virus infection.

ADP-ribosylation is a highly dynamic and fully reversible post-translational modification performed by poly(ADP-ribose) polymerases (PARPs) that modulates protein function, abundance, localization and turnover. Here we show that influenza A virus infection causes a rapid and dramatic upregulation of global ADP-ribosylation that inhibits viral replication. Mass spectrometry defined for the first time the global ADP-ribosylome during infection, creating an infection-specific profile with almost 4,300 modification sites on ~1,080 host proteins, as well as over 100 modification sites on viral proteins. Our data indicate that the global increase likely reflects a change in the form of ADP-ribosylation rather than modification of new targets. Functional assays demonstrated that modification of the viral replication machinery antagonizes its activity and further revealed that the anti-viral activity of PARPs and ADP-ribosylation is counteracted by the influenza A virus protein NS1, assigning a new activity to the primary viral antagonist of innate immunity. We identified PARP1 as the enzyme producing the majority of poly(ADP-ribose) present during infection. Influenza A virus replicated faster in cells lacking PARP1, linking PARP1 and ADP-ribosylation to the anti-viral phenotype. Together, these data establish ADP-ribosylation as an anti-viral innate immune-like response to viral infection antagonized by a previously unknown activity of NS1.

Synthesis, Characterization, and Biological Evaluation of N-Methyl Derivatives of Norbelladine.

Norbelladine derivatives have garnered attention in recent years due to their diverse biological activities and pivotal role in the biosynthetic pathway of Amaryllidaceae alkaloids. This study reports the synthesis and biological evaluation of four O,N-methylated derivatives of norbelladine. These derivatives were synthesized through a three-step process: forming imine intermediates from benzaldehydes with tyramine, hydrogenating them to secondary amines, and N-methylating these amines. The products were purified and characterized by 1H and 13C NMR spectroscopy. Their biological activities were assessed by evaluating their ability to inhibit Alzheimer's disease-related enzymes acetylcholinesterase and butyrylcholinesterase. Additionally, the cytotoxic activity of the novel derivatives was tested against cancer cell lines derived from hepatocarcinoma (Huh7), adenocarcinoma (HCT-8), and acute myeloid leukemia (THP-1) cells, and their antiviral properties against a human coronavirus (HCoV-OC43), a flavivirus (dengue virus), and a lentivirus (pseudotyped HIV-1). Docking analysis was performed to understand the impact of the N-methylation on their pharmacological relevance. The results indicate that while N-methylation does not significantly affect antiviral activity, it enhances butyrylcholinesterase inhibition for N-methylnorbelladine and 4'-O,N-dimethylnorbelladine. Overall, this work enhances our understanding of norbelladine derivatives, provides new tools for Alzheimer's disease research, and lays the groundwork for future pharmaceutical developments.

Inhibition of fish rhabdovirus demonstrates application prospect of two methylimidazole phenylpropanoid-based small molecules in aquaculture

Aquaculture faces significant challenges, notably spring viremia of carp (SVC) caused by spring viremia of carp virus (SVCV), which is particularly devastating due to its high mortality rates and rapid transmission among fish populations. This study introduces two novel methylimidazole phenylpropanoid-based small molecules, LML1013 and LML1014, synthesized for combating SVCV in aquaculture environments. Comprehensive in vitro and in vivo evaluations demonstrated that these compounds have potent antiviral activities against SVCV. They effectively inhibited SVCV replication in epithelioma papulosum cyprinid (EPC) cells and significantly reduced mortality rates in infected juvenile common carp. Further analyses revealed that daily administration of these compounds not only blocked SVCV replication but also stimulated the innate immune responses of the fish, thereby enhancing their overall resistance to viral infection. Notably, the antiviral efficacy was observed in a dose- and time-dependent manner without inducing cytotoxic effects, emphasizing their therapeutic potential. The stability of LML1013 and LML1014 in aquacultural water and their ability to prevent horizontal viral transmission were also confirmed, further supporting their feasibility as treatment options in aquaculture. Overall, the development of LML1013 and LML1014 provides a promising strategy for controlling SVCV outbreaks and enhancing the sustainability of fish farming operations. This approach offers significant implications for improving aquaculture biosecurity and effectively managing viral disease threats.

Anti-Coronavirus Activity of Chitosan-Stabilized Liposomal Nanocarriers Loaded with Natural Extracts from Bulgarian Flora.

Disease's severity, mortality rates, and common failures to achieve clinical improvement during the unprecedented COVID-19 pandemic exposed the emergency need for new antiviral therapeutics with higher efficacy and fewer adverse effects. This study explores the potential to encapsulate multi-component plant extracts in liposomes as optimized delivery systems and to verify if they exert inhibitory effects against human seasonal betacoronavirus OC43 (HCoV-OC43) in vitro. The selection of Sambucus nigra, Potentilla reptans, Allium sativum, Aesculus hippocastanum, and Glycyrrhiza glabra L. plant extracts was based on their established pharmacological and antiviral properties. The physicochemical characterization of extract-loaded liposomes was conducted by DLS and electrokinetics. Encapsulated amounts of the extract were evaluated based on the total flavonoid content (TFC) and total polyphenol content (TPC) by colorimetric methods. The BALB 3T3 neutral red uptake (NRU) phototoxicity/cytotoxicity assay was used to estimate compounds' safety. Photo irritation factors (PIFs) of the liposomes containing extracts were <2 which assigned them as non-phototoxic substances. The antiviral capacities of liposomes containing medicinal plant extracts against HCoV-OC43 were measured by the cytopathic effect inhibition test in susceptible HCT-8 cells. The antiviral activity increased by several times compared to "naked" extracts' activity reported previously. A. hippocastanum extract showed 16 times higher inhibitory properties reaching a selectivity index (SI) of 58.96. Virucidal and virus-adsorption effects were investigated using the endpoint dilution method and ∆lgs comparison with infected and untreated controls. The results confirmed that nanoparticles do not directly affect the viral surface or cell membrane, but only serve as carriers of the active substances and the observed protection is due solely to the intracellular action of the extracts.

From Nature to Drug: Overview and CADD Approach of Anacardic Acid to Propose their Biological Potential

Anacardic acids are natural compounds found in various plant families, such as Anacardiaceae, Geraniaceae, Ginkgoaceae, and Myristicaceae, among others. Several activities have been reported regarding these compounds, including antibacterial, antioxidant, anticancer, anti-inflammatory, and antiviral activities, showing the potential therapeutic applicability of these compounds. From a chemical point of view, they are structurally made up of salicylic acids substituted by an alkyl chain containing unsaturated bonds, which can vary in number and position, determining their bioactivity and differentiating them from the various existing forms. Our work aimed to explore the potential of anacardic acids, based on studies that address the bioactivity of these compounds, as well as to establish a greater understanding of the structure-activity relationship of these compounds through in silico methods, with a focus on the elucidation of a possible drug target through the application of computer-aided drug design, CADD.

Synergistic effects of β-Cyclodextrin derivative inclusion complexes with favipiravir to enhance solubility and antiviral efficacy against Herpes Simplex virus type 1 (HSV-1)

In this study, the formation of β-cyclodextrin derivatives (β-Cyclodextrin; β-CD, Hydroxypropyl-β-Cyclodextrin; Hβ-CD, and Sulfobutylether-β-Cyclodextrin; Sβ-CD) inclusion complexes with favipiravir (FPR) was confirmed using various spectroscopic and analytical techniques. These complexes were shown to enhance FPR solubility and antiviral activity against herpes simplex virus type 1 (HSV-1). UV–visible and fluorescence spectroscopy revealed a continuous increase in FPR absorbance and fluorescence intensity with increasing β-CD concentrations, indicating the successful formation of 1:1 inclusion complexes. The prepared β-CD solid complexes were characterized using FTIR, XRD, FESEM, and TGA-DSC, which highlighted significant surface properties, morphological changes, and improved thermal stability. Phase solubility studies demonstrated enhanced FPR solubility in the presence of the β-CDs, with stability constants (Ks) following the order: Hβ-CD (694.8 M−1) > Sβ-CD (418.4 M−1) > β-CD (364.3 M−1). In-vitro release studies showed that the Hβ-CD complex achieved a higher cumulative release of 90.16 ± 1.94 % over 90 min compared to free FPR (25.32 ± 0.29 %), attributed to its greater solubility. Molecular docking provided insights into the interaction mechanisms, revealing higher binding affinities and stability for FPR with β-CD. In-vitro antiviral assays against HSV-1 demonstrated significant viral titer reductions for free FPR with β-CDs, with Hβ-CD outperforming others due to its rapid release profile after 96 h of incubation, confirming its potential for improved antiviral formulations. The cytotoxic effects of FPR and its β-CDs inclusion complexes were evaluated on Vero cells using an MTT assay over 96 h, showing reduced cytotoxicity for the inclusion complexes compared to free FPR. Additionally, cellular uptake studies revealed that β-CDs inclusion complexes conjugated with DAPI and FITC exhibited greater intensity within Vero cells compared to free FPR.

Development, Validation, and Greenness Assessment of HPLC and ATR-FTIR for Mangiferin Quantitative Analysis in Raw Material

Due to the benefits of mangiferin, including antidiabetic, antibacterial, antiviral, antioxidant, and anti-inflammatory activities, it is a natural raw material used in botanical health and cosmetic products. This research aims to develop and validate analytical methods for the quantification of mangiferin in raw material, isolated from Mangifera indica L. leaves, using high performance liquid chromatography (HPLC) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The greenness assessment of both analytical methods was performed. The results indicated that both methods were validated in terms of specificity, linearity, range, detection limit, quantitation limit, accuracy, and precision. The ranges of mangiferin used in HPLC and ATR-FTIR were 30 to 360 µg/mL and 5.00 to 27.27% w/w, respectively. The mangiferin content in five batches, analyzed by using the validated HPLC and ATR-FTIR, ranged from 88.35 to 109.4% w/w and 90.7 to 111.8% w/w, respectively. Statistical analysis using a paired t-test revealed no significant difference in the mangiferin quantity between the two techniques at a 95% confidence level. The greenness scores of the HPLC and ATR-FTIR determined according to AGREE metric were 0.49 and 0.81, respectively. Both methods can be applied to quantify mangiferin content and control the quality of mangiferin raw material. Additionally, the validated ATR-FTIR, which proposed excellent environmental friendliness, was suggested as an alternative analytical method for routine assay of mangiferin raw material.

Inhibition of influenza virus infection in mice by pulmonary administration of a spray dried antiviral drug

Increasing resistance to antiviral drugs approved for the treatment of influenza urges the development of novel compounds. Ideally, this should be complemented by a careful consideration of the administration route. 6′siallyllactosamine-functionalized β-cyclodextrin (CD-6′SLN) is a novel entry inhibitor that acts as a mimic of the primary attachment receptor of influenza, sialic acid. In this study, we aimed to develop a dry powder formulation of CD-6′SLN to assess its in vivo antiviral activity after administration via the pulmonary route. By means of spray drying the compound together with trileucine, a dispersion enhancer, we created a powder that retained the antiviral effect of the drug, remained stable under elevated temperature conditions and performed well in a dry powder inhaler. To test the efficacy of the dry powder drug against influenza infection in vivo, infected mice were treated with CD-6′SLN using an aerosol generator that allowed for the controlled administration of powder formulations to the lungs of mice. CD-6′SLN was effective in mitigating the course of the disease compared to the control groups, reflected by lower disease activity scores and by the prevention of virus-induced IL-6 production. Our data show that CD-6′SLN can be formulated as a stable dry powder that is suitable for use in a dry powder inhaler and is effective when administered via the pulmonary route to influenza-infected mice.

Antiviral effect of oversulfated kappa-carrageenan derivatives against COVID-19 for spray coating application on facemasks

The COVID-19 pandemic caused by SARS-CoV-2 has spurred the urgent need for effective antiviral strategies. In this work, we explored the potential of oversulfated kappa-carrageenan (OSKC) in spray-coated facemasks for SARS-CoV-2 inhibition pathway. The sulfated derivative was synthesized with sulfur trioxide pyridine complex in dimethylformamide solution. The antiviral efficacy of OSKC at different concentrations and spray-coated facemasks was evaluated using betacoronavirus Murine Hepatitis Virus strain 3, revealing a significant reduction in viral load compared to commercial kappa-carrageenan. Furthermore, the characterization techniques assessed the effect of the position of the introduced sulfate groups on the antiviral activity and on the physicochemical characteristics. OSKC is able to bind specific proteins of enveloped viruses, preventing viral attachment into target cells. Overall, this study demonstrates the feasibility and effectiveness of OSKC spray coating for breathable facemasks with antimicrobial properties, offering a promising approach to enhancing personal protective equipment against viral transmission in healthcare and community settings.

SARS-CoV-2 Delta and Omicron variants resist spike cleavage by human airway trypsin-like protease.

Soluble host factors in the upper respiratory tract can serve as the first line of defense against SARS-CoV-2 infection. In this study, we described the identification and function of a human airway trypsin-like protease (HAT), capable of reducing the infectivity of ancestral SARS-CoV-2. Further, in mouse models, HAT analogue expression was upregulated by SARS-CoV-2 infection. The antiviral activity of HAT functioned through the cleavage of the SARS-CoV-2 spike glycoprotein at R682. This cleavage resulted in inhibition of the attachment of ancestral spike proteins to host cells, which inhibited the cell-cell membrane fusion process. Importantly, exogenous addition of HAT notably reduced the infectivity of ancestral SARS-CoV-2 in vivo. However, HAT was ineffective against the Delta variant and most circulating Omicron variants, including the BQ.1.1 and XBB.1.5 subvariants. We demonstrate that the P681R mutation in Delta and P681H mutation in the Omicron variants, adjacent to the R682 cleavage site, contributed to HAT resistance. Our study reports what we believe to be a novel soluble defense factor against SARS-CoV-2 and resistance of its actions in the Delta and Omicron variants.

Antiviral activity of Nigella sativa oil against two SARS-CoV-2surrogates in vitro as a dietary product

Background: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is primarily transmitted via aerosol and droplets, but environmental surfaces or potentially contaminated foods may contribute to further viral transmission. Nigella sativa seed (black cumin seed) oil possesses various biological activities against bacteria, fungi, parasites, orviruses. Objectives: This study aimed to explore black cumin seed oil (BSO) with anti-SARS-CoV-2 activities using bovine coronavirus (BCoV) and human coronavirus (HCoV) OC43 as surrogates. Methods and Results: BSO was tested at 1-100 mL/L concentrations for cytotoxicity towards human rectal tumor (HRT-18G) cells and 0.1-10 mL/L for efficacy against BCoV and HCoV OC43 in suspension. Two coronaviruses were separately mixed with BSO suspension and incubated for various times (0, 15, 30, 45, and 60 min) at 4, 23, and 37°C. The virus titerreduction was determined by median tissue culture infectious dose (TCID50) assay with HRT-18G cells as the host. BSO concentrations of 1-20 mL/L exhibited low cytotoxicity (&lt;10%) towards HRT-18G cells. The inactivation of coronaviruses by BSO was concentration-, temperature-, and exposure time-dependent. At 37°C, BSO reduced 2.0 logs of BCoV and3.0 logs of HCoV OC43 in 60 min, respectively. Specifically, half maximal effective concentration (EC50) of BSO at 4, 23, and 37°C after the 1-h exposure was 4.28, 3.06, and 0.87 mL/L against BCoV, respectively, and 0.61, 0.61 and 0.48 mL/L against HCoV OC43, respectively. Moreover, BSO didn’t affect the attachment of BCoV and HCoV OC43 into host cells. Conclusion: Our findings on the inhibition activity of BSO against SARS-CoV-2 surrogates suggested the potential use of this natural product in mitigating SARS-CoV-2 infection. Our results also suggest that HCoV OC43 may be a more appropriate surrogate for SARS-CoV-2 to screen antiviral dietary products. Keywords: Nigella sativa, SARS-CoV-2 surrogates, antiviral activity, quantitative suspension test, dietary supplement

The 3D-QSAR Study, Molecular Docking, and ADMET Analysis of Darunavir Derivatives of HIV-1 Protease Inhibitors

Background: Acquired Immunodeficiency Syndrome (AIDS) is one of most prevalent infectious diseases in the world , and HIV-1 protease (PR) is a vital target of drug design. Nowadays, three-dimensional quantitative structure-activity relationships (3D-QSAR) are applied to help design new protease inhibitions (PIs). Objective: The primary objective of this study is to apply the 3D-QSAR study to a series of 42 derivatives of Darunavir (DRV) and to design new molecules possessing high antivirus activity. Methods: Partial Least Squares (PLS) were used to cross-validate the dataset of compounds, and the optimal number of principal components (ONC), cross-validate coefficient (q²), standard error of estimate (SEE), non-cross-validated correlation coefficient (R²) and fisher test value (F) were calculated to assess model robustness. In this study, the CoMSIA-DAH model (q²=0.754, r²= 0.988, rpred2=0.57) possessed the highest predicted activity. Newly designed molecules were analyzed by docking studies with compound 25 taken as a template. Results: Within eight newly designed drugs, compound N02 possessed the highest antivirus activity (IC50=0.00461 nM) predicted by the CoMSIA-DAH model. The Surflex-Dock module of SYBYL-X 2.0 was used to affirm the predicted anti-PR activity of the newly designed compounds and the results of docking complex structure could be visualized. All newly designed molecules were in agreement with CSore above four and the docking study revealed that Asp29, Asp30, Ile50, Asp124, Asp128, Asp129 and Ile149 were critical residues in the process of inhibiting PR. Conclusion: One of the main aspects of this study is the successful design of a series of molecules with excellent investigatory values, which elucidates explicit quantitative structure-activity relationships of DRV derivatives and will provide significant suggestions for future pharmaceutical research.

Sonication-Assisted Self-Assembled Resveratrol Nanoparticles with Enhanced Antiviral and Anti-inflammatory Activity against Respiratory Syncytial Virus-Induced Pneumonia.

Respiratory syncytial virus (RSV)-induced viral pneumonia in children is common worldwide. Its high occurrence and lack of an effective vaccine make it a leading cause of death in children. Severe RSV infection can trigger uncontrolled inflammatory responses in patients, so the development of small molecule drugs with the dual function of "direct antivirus" and "inflammatory response regulation" is welcome. Resveratrol (Res) has been reported to have antiviral and anti-inflammatory pharmacological effects, but its application is limited because of its poor water solubility and oral bioavailability. Based on small-molecule nanotechnology, we developed a sonication-assisted self-assembly method for preparing insoluble Res into highly soluble resveratrol nanoparticles (Res NPs). The obtained Res NPs exhibited a higher water solubility and a faster dissolution rate, which was more conducive to the effectiveness of Res in addressing RSV-induced viral pneumonia. In vitro studies had shown that Res NPs played an antiviral role by inhibiting RSV replication and reducing the production of pro-inflammatory cytokines. Nebulized inhalation administration of Res NPs prolonged the drug's residence time in the lungs, which appears to increase the accumulation and effectiveness of Res NPs. Additionally, in vivo studies had demonstrated significant benefits of Res NPs in inhibiting RSV viral load and improving the pulmonary microenvironment in RSV-infected mice. Both antiviral and anti-inflammatory experiments had confirmed that the pharmacological activity of Res NPs is superior to that of Res. This suggested that nanosizing Res was an effective way to enhance the original pharmacological activity of Res and also offered a new formulation strategy for treating viral pneumonia.