Recent advancements for the evaluation of anti-viral activities of natural products

Unveiling the Potent Antiviral and Antioxidant Activities of an Aqueous Extract from Caesalpinia mimosoides Lamk: Cheminformatics and Molecular Docking Approaches

Our group previously demonstrated that Caesalpinia mimosoides Lamk exhibits many profound biological properties, including anticancer, antibacterial, and antioxidant activities. However, its antiviral activity has not yet been investigated. Here, the aqueous extract of C. mimosoides was prepared from the aerial parts (leaves, stalks, and trunks) to see whether it exerts anti-influenza (H1N1) effects and to reduce the organic solvents consumed during extraction, making it a desirable approach for the large-scale production for medical uses. Our plant extract was quantified to contain 7 g of gallic acid (GA) per 100 g of a dry sample, as determined using HPLC analysis. It also exerts potent antioxidant activities comparable to those of authentic GA. According to untargeted metabolomics (UPLC-ESI(-)-QTOF-MS/MS) with the aid of cheminformatics tools (MetFrag (version 2.1), SIRIUS (version 5.8.3), CSI:FingerID (version 4.8), and CANOPUS), the major metabolite was best annotated as "gallic acid", phenolics (e.g., quinic acid, shikimic acid, and protocatechuic acid), sugar derivatives, and dicarboxylic acids were deduced from this plant species for the first time. The aqueous plant extract efficiently inhibited an influenza A (H1N1) virus infection of MDCK cells with an IC50 of 5.14 µg/mL. Of equal importance, hemolytic activity was absent for this plant extract, signifying its applicability as a safe antiviral agent. Molecular docking suggested that GA interacts with conserved residues (e.g., Arg152 and Asp151) located in the catalytic inner shell of the viral neuraminidase (NA), sharing the same pocket as those of anti-neuraminidase drugs, such as laninamivir and oseltamivir. Additionally, other metabolites were also found to potentially interact with the active site and the hydrophobic 430-cavity of the viral surface protein, suggesting a possibly synergistic effect of various phytochemicals. Therefore, the C. mimosoides aqueous extract may be a good candidate for coping with increasing influenza virus resistance to existing antivirals.

In vitro antiviral effect of Mexican and Brazilian propolis and phenolic compounds against human coronavirus 229E

Propolis is a resinous substance collected by bees (Apis mellifera). It is used for its biological properties. This natural product is available as a safe therapeutic option. Herein, we report the antiviral effects of brown propolis extract from Mexico and green and red propolis extracts from Brazil, as well as their phenolic compounds (quercetin, caffeic acid, and rutin) in preventing infection of MRC-5 cells by HCoV-229E. Normal human fibroblast lung cells (MRC-5) were used to determine the cytotoxicity of the compounds. All samples studied showed antiviral activity. Green and brown propolis extracts, and quercetin exhibited the best EC50 values with values of 19.080, 11.240, and 77.208 µg/mL against HCoV-229E, respectively, and with TC50 of 62.19, 29.192, and 298 µg/mL on MRC-5 cells, respectively. These results are the first in vitro study of the effects of propolis on HCoV-229E and provide the basis for the development of natural formulations against other coronavirus strains.

A Reappraisal of the Antiviral Properties of and Immune Regulation through Dietary Phytochemicals

In the present era of the COVID-19 pandemic, viral infections remain a major cause of morbidity and mortality worldwide. In this day and age, viral infections are rampant and spreading rapidly. Among the most aggressive viral infections are ebola, AIDS (acquired immunodeficiency syndrome), influenza, and SARS (severe acute respiratory syndrome). Even though there are few treatment options for viral diseases, most of the antiviral therapies are ineffective owing to frequent mutations, the development of more aggressive strains, drug resistance, and possible side effects. Traditionally, herbal remedies have been used by healers, including for dietary and medicinal purposes. Many clinical and scientific studies have demonstrated the therapeutic potential of plant-derived natural compounds. Because of unsafe practices like blood transfusions and organ transplants from infected patients, medical supply contamination. Our antiviral therapies cannot achieve sterile immunity, and we have yet to find a cure for these pernicious infections. Herbs have been shown to improve therapeutic efficacy against a wide variety of viral diseases because of their high concentration of immunomodulatory phytochemicals (both immunoinhibitory and anti-inflammatory). Combined with biotechnology, this folk medicine system can lead to the development of novel antiviral drugs and therapies. In this Review, we will summarize some selected bioactive compounds with probable mechanisms of their antiviral actions, focusing on the immunological axis of these compounds.

Antiviral activity of Taurisolo® during bovine alphaherpesvirus 1 infection

Bovine alphaherpesvirus 1 (BoAHV-1), the pathogen causing Infectious Bovine Rhinotracheitis (IBR) and predisposing to polymicrobial infections in cattle, provokes farm economic losses and trading restrictions in the world. However, nontoxic antiviral agents for BoAHV-1 infection are still unavailable, but plant extracts, such as flavonoid derivatives possess activity against BoAHV-1. Taurisolo®, a nutraceutical produced by Aglianico grape pomace, has recently shown promising antiviral activity. Herein, the potential activity of Taurisolo® during BoAHV-1 infection in Madin Darby bovine kidney (MDBK) cells was tested. Taurisolo® enhanced cell viability and reduced morphological death signs in BoAHV-1-infected cells. Moreover, Taurisolo® influenced the expression of bICP0, the key regulatory protein of BoAHV-1, and it strongly diminished virus yield. These effects were associated with an up-regulation of aryl hydrocarbon receptor (AhR), a transcription factor involved in microbial metabolism and immune response. In conclusion, our findings indicate that Taurisolo® may represent a potential antiviral agent against BoAHV-1 infection. Noteworthy, AhR could be involved in the observed effects and become a new target in antiviral therapy.

In silico identification of deep-sea fungal alkaloids as potential inhibitors of SARS-CoV-2, Delta and Omicron spikes

Aim: Virtual screening of deep-sea fungal metabolites against SARS-CoV-2 Delta and Omicron spikes as potential antivirals. Materials & methods: Deep-sea fungal alkaloids (n ≥ 150) were evaluated against SARS-CoV-2, Delta and Omicron spikes, using various in silico approaches, including Admet scores, physiochemical properties, molecular docking (MD) and MD simulation (150 ns). Results: The test alkaloids complied with Admet scores and physiochemical properties within acceptable ranges, and followed Lipinski's rule of five. Of these, Cladosporium sphaerospermum-derived cladosin K (tetramate alkaloid) for SARS-CoV-2, Cystobasidium laryngis-derived saphenol (phenazine alkaloid) for Delta and Chaetomium globosum-derived chaetoglobosin E (quinoline alkaloid) for Omicron were identified as potential spike-inhibitors. Conclusion: Our data therefore, strongly warrants further experimental validations of cladosin K, saphenol and chaetoglobosin E, especially against the Omicron and Delta spikes.

Computational peptide engineering approach for selection of the new C05 antibody-driven peptide with potency to blocking influenza a virus attachment; from in silico to in vivo

Antiviral drugs are currently used to prevent or treat viral infections like influenza A Virus (IAV). Nonetheless, annual genetic mutations of influenza viruses make them resistant to efficient treatment by current medications. Antiviral peptides have recently attracted researchers' attention and can potentially supplant the current medications. This study aimed to design peptides against IAV propagation. For this purpose, P2 and P3 peptides were computationally designed based on the HCDR3 region of the C05 antibody (a monoclonal antibody that neutralizes influenza HA protein and inhibits the virus attachment). The synthesized peptides were tested against the influenza A virus (A/Puerto Rico/8/34 (H1N1)) in vitro, and the most efficient peptide was selected for in vivo experiments. It was shown that the designed peptide shows much more prophylactic and therapeutic effects against the virus. These findings demonstrated that the designed peptide can control the virus infection without any cytotoxicity effect. Antiviral peptide design is acknowledged as a critical tactic to manage viral infections by preventing viral binding to the host cells.Communicated by Ramaswamy H. Sarma.

Development of an Antiviral Ion-Activated In Situ Gel Containing 18β-Glycyrrhetinic Acid: A Promising Alternative against Respiratory Syncytial Virus

The human respiratory syncytial virus (hRSV) is a major cause of serious lower respiratory infections and poses a considerable risk to public health globally. Only a few treatments are currently used to treat RSV infections, and there is no RSV vaccination. Therefore, the need for clinically applicable, affordable, and safe RSV prevention and treatment solutions is urgent. In this study, an ion-activated in situ gelling formulation containing the broad-spectrum antiviral 18β-glycyrrhetinic acid (GA) was developed for its antiviral effect on RSV. In this context, pH, mechanical characteristics, ex vivo mucoadhesive strength, in vitro drug release pattern, sprayability, drug content, and stability were all examined. Rheological characteristics were also tested using in vitro gelation capacity and rheological synergism tests. Finally, the cytotoxic and antiviral activities of the optimized in situ gelling formulation on RSV cultured in the human laryngeal epidermoid carcinoma (HEp-2) cell line were evaluated. In conclusion, the optimized formulation prepared with a combination of 0.5% w/w gellan gum and 0.5% w/w sodium carboxymethylcellulose demonstrated good gelation capacity and sprayability (weight deviation between the first day of the experiment (T0) and the last day of the experiment (T14) was 0.34%), desired rheological synergism (mucoadhesive force (Fb): 9.53 Pa), mechanical characteristics (adhesiveness: 0.300 ± 0.05 mJ), ex vivo bioadhesion force (19.67 ± 1.90 g), drug content uniformity (RSD%: 0.494), and sustained drug release over a period of 6 h (24.56% ± 0.49). The optimized formulation demonstrated strong anti-hRSV activity (simultaneous half maximal effective concentration (EC50) = 0.05 µg/mL; selectivity index (SI) = 306; pre-infection EC50 = 0.154 µg/mL; SI = 100), which was significantly higher than that of ribavirin (EC50 = 4.189 µg/mL; SI = 28) used as a positive control against hRSV, according to the results of the antiviral activity test. In conclusion, this study showed that nasal in situ gelling spray can prevent viral infection and replication by directly inhibiting viral entry or modulating viral replication.

Structure-based virtual identification of natural inhibitors of SARS-CoV-2 and its Delta and Omicron variant proteins

Aim

Structure-based identification of natural compounds against SARS-CoV-2, Delta and Omicron target proteins.

Materials & methods

Several known antiviral natural compounds were subjected to molecular docking and MD simulation against SARS-CoV-2 Mpro, Helicase and Spike, including Delta and Omicron Spikes.

Results

Of the docked ligands, 20 selected for each complex exhibited overall good binding affinities (-7.79 to -5.06 kcal/mol) with acceptable physiochemistry following Lipinski's rule. Finally, two best ligands from each complex upon simulation showed structural stability and compactness.

Conclusion

Quercetin-3-acetyl-glucoside, Rutin, Kaempferol, Catechin, Orientin, Obetrioside and Neridienone A were identified as potential inhibitors of SARS-CoV-2 Mpro, Helicase and Spike, while Orientin and Obetrioside also showed good binding affinities with Omicron Spike. Catechin and Neridienone A formed stable complexes with Delta Spike.

Synthesis and Evaluation of Piperazine-Tethered Derivatives of Alepterolic Acid as Anticancer Agents

Alepterolic acid is a natural diterpenoid isolated from Aleuritopteris argentea with potential anti-cancer activity. In this study, alepterolic acid was modified to construct a series of arylformyl piperazinyl derivatives (3a-3p). The synthesized derivatives were fully characterized with HRMS, NMR, and IR. Four compounds with inhibition rate higher than 30 % at 10 μM (3f, 3n, 3g and 3k) were further measured to obtain the IC50 values against four cancer cell lines, including hepatoma cell lines HepG2, lung cancer cell lines A549, estrogen receptor-positive cell lines MCF7, and triple-negative breast cancer (TNBC) cell lines MDA-MB-231 by MTT assay. It was found that these compounds were more effective to HepG2 and MDA-MB-231 cells, while less toxic to A549 and MCF7 cells, and compound 3n as the most toxic derivatve against MDA-MB-231 cell lines, with IC50 value of 5.55±0.56 μM. Trypan blue staining and colony formation assay showed that compound 3n inhibited the growth of MDA-MB-231 cells and prevented colony formation. Hoechst staining, flow cytometry and western blot analysis revealed that compound 3n induced caspase-dependent apoptosis in MDA-MB-231 cells. Conclusively, compound 3n was demonstrated to be a potential anti-cancer lead compound for further investigation.

Evaluation of the antiviral potential of gemini surfactants against influenza virus H1N1

Influenza A virus (IAV) affects human health worldwide as a high-risk disease. It can neither be easily controlled by current vaccines and nor be treated by conventional drugs. Gemini surfactants (GS) have shown several properties including antiviral activity. In this study, the antiviral capacity of some GS compounds with different levels of hydrophobicity was examined. The 50% cytotoxic (CC₅₀) and non-cytotoxic (NCTC) concentrations of the compounds were determined by MTT method. The NCTCs, the same as effective concentrations (EC₅₀s), were tested for the antiviral capacity against IAV in different combination treatments for 1 h incubation on MDCK cells. The HA and MTT assays were used to evaluate the virus titer and cell viabilities, respectively. The hemolytic activity of the compounds was also assessed using an HA inhibition assay. To evaluate the apoptotic effect of GS compounds, Annexin V-PI kit was used. The HA titers decreased between 1-6.5 logs, 1-4.5 logs, and 1-5.5 logs in simultaneous, pre- and post-penetration combination treatments, respectively. The cell viability values in all combination treatments were favorable. The HI assay indicated the hemolytic potential of GSs and their physical interaction with viral HA. The apoptosis test results highlighted anti-apoptotic capacity of the GS compounds alone and in the presence of influenza virus especially for the hydrophobic ones. Gemini surfactants were generally more efficacious in simultaneous treatment. Their antiviral potential may be attributed to their physical interaction with viral membrane or HA glycoprotein that disrupts viral particle or blocks viral entry to the cell and inhibits its propagation.

Evaluation of the antibacterial activity of selected Kenyan medicinal plant extract combinations against clinically important bacteria

BACKGROUND

Infectious diseases are a major global public health concern as antimicrobial resistance (AMR) currently accounts for more than 700,000 deaths per year worldwide. The emergence and spread of resistant bacterial pathogens remain a key challenge in antibacterial chemotherapy. This study aims to investigate the antibacterial activity of combined extracts of various Kenyan medicinal plants against selected microorganisms of medical significance.

METHODS

The antibacterial activity of various extract combinations of Aloe secundiflora, Toddalia asiatica, Senna didymobotrya and Camelia sinensis against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Methicillin Resistant Staphylococcus aureus was assessed using the agar well diffusion and the minimum inhibitory concentration in-vitro assays. The checkerboard method was used to evaluate the interactions between the various extract combinations. ANOVA test followed by Tukey's post hoc multiple comparison test was used to determine statistically significant differences in activity (P < 0.05).

RESULTS

At concentrations of 100 mg/ml (10,000 µg/well), the different combinations of the aqueous, methanol, dichloromethane and petroleum ether extracts of the selected Kenyan medicinal plants revealed diverse activity against all the test bacteria. The combination of methanolic C. sinensis and A. secundiflora was the most active against E. coli (14.17 ± 0.22 mm, diameter of zones of inhibition (DZI); MIC 2500 µg/well). The combination of methanolic C. sinensis and S. didymobotrya was the most active against S. aureus (16.43 ± 0.10 mm; MIC 1250 µg/well), K. pneumonia (14.93 ± 0.35 mm, DZI; MIC 1250 µg/well), P. aeruginosa (17.22 ± 0.41 mm, DZI; MIC 156.25 µg/well) and MRSA (19.91 ± 0.31 mm, DZI; MIC 1250 µg/well). The Minimum Inhibitory Concentration of the different plant extract combinations ranged from 10,000 µg/ well to 156.25 µg/well. The ANOVA test indicated statistically significant differences (P < 0.05) between single extracts and their combinations. The fractional inhibitory concentration indices (FICI) showed that the interactions were either synergistic (10.5%), additive (31.6%), indifferent (52.6%), or antagonistic (5.3%) for the selected combinations.

CONCLUSION

This study findings validate the ethnopractice of selectively combining medicinal plants in the management of some bacterial infections in traditional medicine.

Potential antiviral activities of chrysin against hepatitis B virus

BACKGROUND

Interferon and nucleos(t)ide analogues are current therapeutic treatments for chronic Hepatitis B virus (HBV) infection with the limitations of a functional cure. Chrysin (5, 7-dihydroxyflavone) is a natural flavonoid, known for its antiviral and hepatoprotective activities. However, its anti-HBV activity is unexplored.

METHODS

In the present study, the anti-hepatitis B activity of chrysin was investigated using the in vitro experimental cell culture model, HepG2 cells. In silico studies were performed where chrysin and lamivudine (used here as a positive control) were docked with high mobility group box 1 protein (HMGB1). For the in vitro studies, wild type HBV genome construct (pHBV 1.3X) was transiently transfected in HepG2. In culture supernatant samples, HBV surface antigen (HBsAg) and Hepatitis B e antigen (HBeAg) were measured by enzyme-linked immunosorbent assay (ELISA). Secreted HBV DNA and intracellular covalently closed circular DNA (cccDNA) were measured by SYBR green real-time PCR. The 3D crystal structure of HMGB1 (1AAB) protein was developed and docked with the chrysin and lamivudine. In silico drug-likeness, Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) properties of finest ligands were performed by using SwissADME and admetSAR web servers.

RESULTS

Data showed that chrysin significantly decreases HBeAg, HBsAg secretion, supernatant HBV DNA and cccDNA, in a dose dependent manner. The docking studies demonstrated HMGB1 as an important target for chrysin as compared to lamivudine. Chrysin revealed high binding affinity and formed a firm kissing complex with HMGB1 (∆G = - 5.7 kcal/mol), as compared to lamivudine (∆G = - 4.3 kcal/mol), which might be responsible for its antiviral activity.

CONCLUSIONS

The outcome of our study establishes chrysin as a new antiviral against HBV infection. However, using chrysin to treat chronic HBV disease needs further endorsement and optimization by in vivo studies in animal models.

In Vitro Antiviral and Anti-Inflammatory Activities of N-Acetylglucosamine: Development of an Alternative and Safe Approach to Fight Viral Respiratory Infections

Viral respiratory tract infections (RTIs) are responsible for significant morbidity and mortality worldwide. A prominent feature of severe respiratory infections, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is the cytokine release syndrome. Therefore, there is an urgent need to develop different approaches both against viral replication and against the consequent inflammation. N-acetylglucosamine (GlcNAc), a glucosamine (GlcN) derivative, has been developed as an immunomodulatory and anti-inflammatory inexpensive and non-toxic drug for non-communicable disease treatment and/or prevention. Recent studies have suggested that GlcN, due to its anti-inflammatory activity, could be potentially useful for the control of respiratory virus infections. Our present study aimed to evaluate in two different immortalized cell lines whether GlcNAc could inhibit or reduce both viral infectivity and the inflammatory response to viral infection. Two different viruses, frequent cause of upper and lower respiratory tract infections, were used: the H1N1 Influenza A virus (IAV) (as model of enveloped RNA virus) and the Human adenovirus type 2 (Adv) (as model of naked DNA virus). Two forms of GlcNAc have been considered, bulk GlcNAc and GlcNAc in nanoform to overcome the possible pharmacokinetic limitations of GlcNAc. Our study suggests that GlcNAc restricts IAV replication but not Adv infection, whereas nano-GlcNAc inhibits both viruses. Moreover, GlcNAc and mainly its nanoformulation were able to reduce the pro-inflammatory cytokine secretion stimulated by viral infection. The correlation between inflammatory and infection inhibition is discussed.

Recent Advances in Transition-Metal-Catalyzed Reactions of N-Tosylhydrazones

N-Tosylhydrazones are highly versatile precursors for in situ carbene formation and are frequently used in metal-catalyzed cross-coupling reactions. Due to their many applications in organic synthesis, including C–C, C–O, C–N, and C–S bond formation, N-tosylhydrazones have recently received much interest. They can be simply synthesized by reacting an aldehyde or ketone with N-tosylhydrazine to produce a solid N-tosylhydrazone, which is a ‘green’ precursor of diazo compounds. Using a suitable metal catalyst, N-tosylhydrazones show versatile substrate scope for the synthesis of substituted diaminopyrroles, chromenopyrazoles, alkenylpyrazoles, benzofuran thioethers, tetrahydropyridazines, sulfur-containing heterocycles, and benzofurans with potent biological activities and even regioselective N-functionalization reactions. Metal-catalyzed reactions of N-tosylhydrazones for the construction of bioactive heterocycles are still highly in demand. Hence, this review focuses on the recent synthetic application of N-tosylhydrazones influenced by different transition metals with notable features like simple workup procedures, gram-scale synthesis, broad substrate scope, multicomponent processes, cyclization, and carbon–heteroatom bond formation.

1 Introduction

2 Applications of N-Tosylhydrazones

3 Conclusion

In vitro anti-influenza assessment of anionic compounds ascorbate, acetate and citrate

Background

Influenza A virus (IAV) infection remains a serious public health threat. Due to drug resistance and side effects of the conventional antiviral drugs, repurposing the available natural compounds with high tolerability and fewer side effects has attracted researchers’ attention. The aim of this study was to screen in vitro anti-influenza activity of three anionic compounds ascorbate, acetate, and citrate.

Methods

The non-cytotoxic concentration of the compounds was determined by MTT assay and examined for the activity against IAV in simultaneous, pre-, and post-penetration combination treatments over 1 h incubation on Madin-Darby Canine Kidney (MDCK) cell line. The virus titer and viral load were determined using hemagglutination assay (HA) and qPCR, respectively. Few pro-inflammatory and anti-inflammatory cytokines were evaluated at RNA and protein levels by qPCR and ELISA, respectively.

Results

The non-cytotoxic concentrations of the ascorbate (200 mg/ml), acetate and citrate (both 3 mg/ml) reduced the viral titer by 6.5, 4.5, and 1.5 logs in the simultaneous combination treatment. The M protein gene copy number decreased significantly in simultaneous treatment (P < 0.01). The expression of cytokines was also affected by the treatment of these compounds.

Conclusions

These anionic compounds could affect the influenza virus load, thereby reducing pro-inflammatory cytokines and increasing anti-inflammatory cytokines levels.

Bioactive Based Nanocarriers for the Treatment of Viral Infections and SARS-CoV-2

Since ancient times, plants have been used for their medicinal properties. They provide us with many phytomolecules, which serve a synergistic function for human well-being. Along with anti-microbial, plants also possess anti-viral activities. In Western nations, about 50% of medicines were extracted from plants or their constituents. The spread and pandemic of viral diseases are becoming a major threat to public health and a burden on the financial prosperity of communities worldwide. In recent years, SARS-CoV-2 has made a dramatic lifestyle change. This has promoted scientists not to use synthetic anti-virals, such as protease inhibitors, nucleic acid analogs, and other anti-virals, but to study less toxic anti-viral phytomolecules. An emerging approach includes searching for eco-friendly therapeutic molecules to develop phytopharmaceuticals. This article briefly discusses numerous bioactive molecules that possess anti-viral properties, their mode of action, and possible applications in treating viral diseases, with a special focus on coronavirus and various nano-formulations used as a carrier for the delivery of phytoconstituents for improved bioavailability.

Ayurvedic Medicinal Plants Against COVID-19: An In Silico Analysis

Even after one and a half years since the outbreak of COVID-19, its complete and effective control is still far from being achieved despite vaccination drives, symptomatic management with available drugs, and wider lockdowns. This has inspired researchers to screen potential phytochemicals from medicinal plants against SARS-CoV-2, adopting a bio-informatics approach. The current study aimed to assess anti-viral activity of the phytochemicals derived from Ayurvedic medicinal plants against SARS-CoV-2 drug targets [3-chymotrypsin-like protease (3CLpro) and RNA dependent RNA polymerase (RdRp)] using validated in silico methods.3D Structures of 196 phytochemicals from three Ayurvedic plants were retrieved from PubChem and KNApSAcK databases and screened for Absorption Distribution Metabolism Excretion and Toxicity(ADMET) to predict drug-likeness. The phytochemicals were subjected to molecular docking and only three showed promise: Acetovanillonewith a binding affinity of −4.7Kcal/mol with RdRp and −4.1 Kcal/mol with 3CL pro; myrtenol with equivalent values of −4.3 Kcal/mol with RdRP and −3.2 Kcal/mol with 3CLpro; and nimbochalcin with equivalent values of −5.0Kcal/mol with RdRp and −4.9 Kcal/mol with 3CLpro. Molecular dynamics simulation (50ns) analysis was made of 3CLpro and RdRp using Autodock Vina 1.1.2 software and VMD software. After ADMET analysis, 78 phytochemicals were found suitable for molecular docking. Three, namely acetovanillone, myrtenol and nimbochalcin from Picrorhiza kurroa, Azadirachta indica and Cyperus rotundus,respectively,exhibited good binding affinity with 3CLproand RdRp of SARS-CoV-2. Interaction analysis, molecular dynamics simulations and MM-PBSA calculations were executed for two complexes, acetovanillone_RdRp and myrtenol_3CL pro.Acetovanillone_RdRpcomplex did not display any structural change after MD simulation as compared to myrtenol_3CL pro. The overall stability of acetovanillone_6NUR was 154.7 kJ/mol, and for myrtenol_1UJ1 90.5 kJ/mol. In silico analysis revealed that acetovanillone ( Picrorhiza kurroa) and myrtenol ( Cyperus rotundus) possess anti SARS-CoV-2 activity. Further studies are needed to validate their efficacy in biological models.

Potential antiviral effects of some native Iranian medicinal plants extracts and fractions against influenza A virus

Background

Influenza A virus (IAV) infection is a continual threat to the health of animals and humans globally. Consumption of the conventional drugs has shown several side effects and drug resistance. This study was aimed to screen some Iranian medicinal plants extracts and their fractions against influenza A virus.

Methods

Glycyrrhiza glabra (rhizome), Myrtus  commonis (leaves), Melissa officinalis (leaves), Hypericum perforatum (aerial parts), Tilia platyphyllos (flower), Salix alba (bark), and Camellia sinensis (green and fermented leaves) were extracted with 80% methanol and fractionated with chloroform and methanol, respectively. The cytotoxicity of the compounds were determined by MTT colorimetric assay on MDCK cells. The effective concentrations (EC₅₀) of the compounds were calculated from the MTT results compared to the negative control with no significant effects on cell viability. The effects of EC₅₀ of the compounds on viral surface glycoproteins and viral titer were tested by HI and HA virological assays, respectively and compared with oseltamivir and amantadine. Preliminary phytochemical analysis were done for promising anti-IAV extracts and fractions.

Results

The most effective samples against IAV titer (P ≤ 0.05) were crude extracts of G. glabra, M. officinalis and S. alba; methanol fractions of M. communis and M. officinalis; and chloroform fractions of M. communis and C. sinensis (fermented) mostly in co- and pre-penetration combined treatments. The potential extracts and fractions were rich in flavonoids, tannins, steroids and triterpenoids.

Conclusion

The outcomes confirmed a scientific basis for anti-influenza A virus capacity of the extracts and fractions from the selected plants for the first time, and correlated their effects with their phytochemical constituents. It is worth focusing on elucidating pure compounds and identifying their mechanism(s) of action.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03423-x.

Herpes Labialis: A New Possibility for Topical Treatment with Well-Elucidated Drugs

Mucocutaneous infections caused by Herpes simplex virus (HSV-1 and HSV-2) are characterized by the appearance of vesicles that cause pain and embarrassment to the carrier. The standard treatment is based on the use of antivirals in gels or ointments, however, relapses are common. Local anesthetics decrease the pain caused by the lesion, in addition to showing antiviral properties. Semi-solid form facilitates application and its transformation into a thin film favors the maintenance of the formulation in place, with a more discreet final aspect. The objective of this study was to develop and evaluate formulations containing anesthetics for the treatment of cold sores. For this purpose, two semi-solid film-forming formulations were developed and evaluated, containing HPMC K100, lidocaine (LIDO) and prilocaine (PRILO) combined with adjuvants, in the presence (F1T) or not (F1) of the absorption promoter Transcutol®. The mixture of PRILO and LIDO resulted in the formation of a eutectic mixture (EM), essential for penetration of drugs into the skin. The quantification of drugs was performed by HPLC (High Performance Liquid Chromatography), and Transcutol® did not influence the release of drugs from the formulation. The bioadhesiveness of the formulation was evaluate and the drugs did not impair the adhesive potential of the polymers used. The formulations were evaluated in vivo for skin irritation and did not show any negative sign on macroscopic examination. The in vivo efficacy test proved the anesthetics' ability to decrease the lesions caused by HSV-1. Thus, the proposed formulations proved to be good alternatives to the treatment of oral lesions caused by HSV-1.

Natural Products with Inhibitory Activity against Human Immunodeficiency Virus Type 1

Infections caused by human immunodeficiency virus (HIV) are considered one of the main public health problems worldwide. Antiretroviral therapy (ART) is the current modality of treatment for HIV-1 infection. It comprises the combined use of several drugs and can decrease the viral load and increase the CD4⁺ T cell count in patients with HIV-1 infection, thereby proving to be an effective modality. This therapy significantly decreases the rate of morbidity and mortality owing to acquired immunodeficiency syndrome (AIDS) and prolongs and improves the quality of life of infected patients. However, nonadherence to ART may increase viral resistance to antiretroviral drugs and transmission of drug-resistant strains of HIV. Therefore, it is necessary to continue research for compounds with anti-HIV-1 activity, exhibiting a potential for the development of an alternative or complementary therapy to ART with low cost and fewer side effects. Natural products and their derivatives represent an excellent option owing to their therapeutic potential against HIV. Currently, the derivatives of natural products available as anti-HIV-1 agents include zidovudine, an arabinonucleoside derivative of the Caribbean marine sponge (Tectitethya crypta), which inhibits the reverse transcriptase of the virus. This was the first antiviral agent approved for treatment of HIV infection. Additionally, bevirimat (isolated from Syzygium claviflorum) and calanolide A (isolated from Calophyllum sp.) are inhibitors of viral maturation and reverse transcription process, respectively. In the present review, we aimed to describe the wide repertoire of natural compounds exhibiting anti-HIV-1 activity that can be considered for designing new therapeutic strategies to curb the HIV pandemic.

Phytochemical Moieties From Indian Traditional Medicine for Targeting Dual Hotspots on SARS-CoV-2 Spike Protein: An Integrative in-silico Approach

SARS-CoV-2 infection across the world has led to immense turbulence in the treatment modality, thus demanding a swift drug discovery process. Spike protein of SARS-CoV-2 binds to ACE2 receptor of human to initiate host invasion. Plethora of studies demonstrate the inhibition of Spike-ACE2 interactions to impair infection. The ancient Indian traditional medicine has been of great interest of Virologists worldwide to decipher potential antivirals. Hence, in this study, phytochemicals (1,952 compounds) from eight potential medicinal plants used in Indian traditional medicine were meticulously collated, based on their usage in respiratory disorders, along with immunomodulatory and anti-viral potential from contemporary literature. Further, these compounds were virtually screened against Receptor Binding Domain (RBD) of Spike protein. The potential compounds from each plant were prioritized based on the binding affinity, key hotspot interactions at ACE2 binding region and glycosylation sites. Finally, the potential hits in complex with spike protein were subjected to Molecular Dynamics simulation (450 ns), to infer the stability of complex formation. Among the compounds screened, Tellimagrandin-II (binding energy of −8.2 kcal/mol and binding free energy of −32.08 kcal/mol) from Syzygium aromaticum L. and O-Demethyl-demethoxy-curcumin (binding energy of −8.0 kcal/mol and binding free energy of −12.48 kcal/mol) from Curcuma longa L. were found to be highly potential due to their higher binding affinity and significant binding free energy (MM-PBSA), along with favorable ADMET properties and stable intermolecular interactions with hotspots (including the ASN343 glycosylation site). The proposed hits are highly promising, as these are resultant of stringent in silico checkpoints, traditionally used, and are documented through contemporary literature. Hence, could serve as promising leads for subsequent experimental validations.

Jaceosidin: A Natural Flavone with Versatile Pharmacological and Biological Activities

Nature always remains an inexhaustible source of treasures for mankind. It remains a mystery for every challenge until the completion of the challenge. While we talk about the complicated health issues, nature offers us a great variety of chemical scaffolds and their various moieties packed in the form of natural products e.g., plants, microorganisms (fungi, algae, protozoa), and terrestrial vertebrates and invertebrates. This review article is an update about jaceosidin, a bioactive flavone, from genus Artemisia. This potentially active compound exhibits a variety of pharmacological activities including anti-inflammatory, anti-oxidant, anti-bacterial, antiallergic and anti-cancer activities. The bioactivities and the therapeutic action of jaceosidin, especially the modulation of different cell signaling pathways (ERK1/2, NF-κB, PI3K/Akt and ATM-Chk1/2) which become deregulated in various pathological disorders, have been focused here. The reported data suggest that the bioavailability of this anti-cancer compound should be enhanced by utilizing various chemical, biological and computational techniques. Moreover, it is recommended that researchers and scientists should work on exploring the mode of action of this particular flavone to precede it further as a potent anti-cancer compound.

Anti-influenza A virus activity of two Newtonia species and the isolated compound myricetin-3-o-rhamnoside

BACKGROUND

Some viruses play a key role in the disturbance of the digestive system. The common viruses which cause infectious diarrhoea (gastroenteritis) include astrovirus, caliciviruses, coronavirus and torovirus which are single-stranded RNA viruses. Influenza A virus (H1N1) also causes diarrhoea in addition to being associated with respiratory symptoms. In preliminary studies, Newtonia hildebrandtii and N. buchananii leaf extracts had good antibacterial activity against some bacteria implicated in causing diarrhoea. The aim of this study was to evaluate the anti-influenza activity of two Newtonia species extracts and the isolated compound (myricitrin).

METHODS

N. hildebrandtii and N. buchananii acetone, and MeOH: DCM (methanol-dichloromethane) leaf and stem extracts, and an antibacterial compound myricetin-3-o-rhamnoside (myricitrin), isolated from N. buchananii, were evaluated for their antiviral efficacy against influenza A virus (IAV) PR8/34/H1N1 as a model organism. The MTT and hemagglutination assays were used to assess the extracts and compound interference with cell viability and viral surface HA glycoprotein. The quantitative real-time PCR was performed to assess the viral load.

RESULTS

Plant extracts of N. hildebrandtii and N. buchananii were effective against IAV. The extracts in combination with H1N1 showed highly significant antiviral activity (P < 0.01) and maintained cell viabilities (P < 0.05). Myricitrin was non-cytotoxic at concentration 104 μg/ml. Myricitrin was most effective against IAV in a co-penetration combined treatment, thereby confirming the inhibitory effect of this compound in the viral attachment and entry stages. Myricitrin treatment also resulted in the highest viability of the cells in co-penetration treatment. The activity of myricitrin indicates the potential of the extracts in controlling viral infection at the attachment stage. The antiviral effect of myricitrin on IAV load in MDCK cell culture was confirmed using quantitative real-time PCR.

CONCLUSION

Data from this study support further research and development on Newtonia hildebrandtii, Newtonia buchananii and myricitrin to address diarrhoea and related conditions caused by viruses in both human and veterinary medicine. Further work needs to be conducted on the activity of the extracts and the purified compound on other viruses of importance which have similar symptoms to influenza virus such as the coronavirus which led to a recent global pandemic.

Quantitative and Molecular Similarity Analyses of the Metabolites of Cold- and Hot-Natured Chinese Herbs

Background

Based on the theory of traditional Chinese medicine, Chinese herbs possess four different medicinal properties: hot, warm, cold, and cool. These serve as a reference guide for these herbal medicines. However, the molecular mechanisms supporting their relevance remain unclear.

Methods

We performed metabolomics based on capillary electrophoresis-time-of-flight mass spectrometry (CE-TOF/MS) and multivariate data analysis for the structural identification of compounds of cold- and hot-natured Chinese herbs.

Results

To this end, 30 selected herbs were analyzed and a total of 416 metabolites were identified via CE-TOF/MS, of which 193 compounds were detected in most herbs. The observed profiles offered the potential to understand the mechanism of association between the compounds and nature of the Chinese herbs. Comparison of the similarity in terms of chemical and molecular structures and content revealed that hot-natured herbs contained more nucleotides. In contrast, principal component analysis revealed the presence of more amino acid compounds in cold-natured herbs.

Conclusion

Comparing the structural similarities between the samples using the Tanimoto coefficient revealed that a general non-specific structure was observed between cold- and hot-natured herbs; however, the distribution of the molecular groups seemed to contribute more toward the energy properties.

Biomaterials-based formulations and surfaces to combat viral infectious diseases

Rapidly growing viral infections are potent risks to public health worldwide. Accessible virus-specific antiviral vaccines and drugs are therapeutically inert to emerging viruses, such as Zika, Ebola, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Therefore, discovering ways to prevent and control viral infections is among the foremost medical challenge of our time. Recently, innovative technologies are emerging that involve the development of new biomaterial-based formulations and surfaces endowed with broad-spectrum antiviral properties. Here, we review emerging biomaterials technologies for controlling viral infections. Relevant advances in biomaterials employed with nanotechnology to inactivate viruses or to inhibit virus replication and further their translation in safe and effective antiviral formulations in clinical trials are discussed. We have included antiviral approaches based on both organic and inorganic nanoparticles (NPs), which offer many advantages over molecular medicine. An insight into the development of immunomodulatory scaffolds in designing new platforms for personalized vaccines is also considered. Substantial research on natural products and herbal medicines and their potential in novel antiviral drugs are discussed. Furthermore, to control contagious viral infections, i.e., to reduce the viral load on surfaces, current strategies focusing on biomimetic anti-adhesive surfaces through nanostructured topography and hydrophobic surface modification techniques are introduced. Biomaterial surfaces functionalized with antimicrobial polymers and nanoparticles against viral infections are also discussed. We recognize the importance of research on antiviral biomaterials and present potential strategies for future directions in applying these biomaterial-based approaches to control viral infections and SARS-CoV-2.

Evaluation of certain medicinal plants compounds as new potential inhibitors of novel corona virus (COVID-19) using molecular docking analysis

SARS-CoV-2 is a new strain of coronavirus that appeared in China in December 2019, in recent years, great progress has been made in developing new antiviral drugs, and natural products, are important sources of potential and new antiviral drugs. The present study aimed to assess some biologically active compounds present in medicinal plants as potential COVID-19 inhibitors, using molecular docking methods. The Docking study was performed by Molecular Operating Environment software (MOE). About 20 Compounds were screened in this study; these compounds were selected based on classification of their chemical origin and their antiviral activity from literature. These compounds might be used to inhibit COVID-19 infection. The results demonstrate the effectiveness of this screening strategy, which can lead to rapid drug discovery in response to new infectious diseases. The results showed that many compounds isolated from medicinal plants such as; Gallic acid (- 17.45), Quercetin (- 15.81), Naringin (- 14.50), Capsaicin (- 13.90), and Psychotrine (- 13.5) are important sources for novel antiviral drugs targeting COVID-19.

Network machine learning maps phytochemically rich "Hyperfoods" to fight COVID-19

In this paper, we introduce a network machine learning method to identify potential bioactive anti-COVID-19 molecules in foods based on their capacity to target the SARS-CoV-2-host gene-gene (protein-protein) interactome. Our analyses were performed using a supercomputing DreamLab App platform, harnessing the idle computational power of thousands of smartphones. Machine learning models were initially calibrated by demonstrating that the proposed method can predict anti-COVID-19 candidates among experimental and clinically approved drugs (5658 in total) targeting COVID-19 interactomics with the balanced classification accuracy of 80-85% in 5-fold cross-validated settings. This identified the most promising drug candidates that can be potentially "repurposed" against COVID-19 including common drugs used to combat cardiovascular and metabolic disorders, such as simvastatin, atorvastatin and metformin. A database of 7694 bioactive food-based molecules was run through the calibrated machine learning algorithm, which identified 52 biologically active molecules, from varied chemical classes, including flavonoids, terpenoids, coumarins and indoles predicted to target SARS-CoV-2-host interactome networks. This in turn was used to construct a "food map" with the theoretical anti-COVID-19 potential of each ingredient estimated based on the diversity and relative levels of candidate compounds with antiviral properties. We expect this in silico predicted food map to play an important role in future clinical studies of precision nutrition interventions against COVID-19 and other viral diseases.

Anti-Zika virus activity of several abietane-type ferruginol analogues

Abietane diterpenoids are naturally occurring plant metabolites with a broad spectrum of biological effects including antibacterial, antileishmanial, antitumor, antioxidant, as well as antiinflammatory activities. Recently, we found that some analogues of natural ferruginol ( 2 ) actively inhibited dengue virus 2 (DENV-2) replication. Due to the similarity with DENV, we envisaged that abietane diterpenoids would also be active against Zika virus (ZIKV). Six selected semi-synthetic abietane derivatives of (+)-dehydroabietylamine ( 3 ) were tested. Cytotoxicity was determined by MTT assay in Vero cells. In vitro anti-ZIKV (clinical isolate, IMT17) activity was evaluated by plaque assay. Interestingly, these molecules showed potential as anti-ZIKV agents, with EC₅₀ values ranging from 0.67 to 18.57 µM, and cytotoxicity (CC₅₀ values) from 2.56 to 35.09 µM. The 18-Oxoferruginol (8) (EC₅₀ = 2.60 µM, SI = 13.51) and 12-nitro-N-benzoyldehydroabietylamine (9) (EC₅₀= 0.67 µM, SI = 3.82) were the most active compounds, followed by 12-hydroxy-N-tosyldehydroabietylamine ( 7 ) (EC₅₀ = 3.58 µM, SI = 3.20) and 12-hydroxy-N,N-phthaloyldehydroabietylamine ( 5 ) (EC₅₀ = 7.76 µM, SI = 1.23). To the best of our knowledge, this is the first report on anti-Zika virus properties of abietanes.

Effective Antiviral Medicinal Plants and Biological Compounds Against Central Nervous System Infections: A Mechanistic Review

BACKGROUND AND OBJECTIVE

Infectious diseases are amongst the leading causes of death in the world and central nervous system infections produced by viruses may either be fatal or generate a wide range of symptoms that affect global human health. Most antiviral plants contain active phytoconstituents such as alkaloids, flavonoids, and polyphenols, some of which play an important antiviral role. Herein, we present a background to viral central nervous system (CNS) infections, followed by a review of medicinal plants and bioactive compounds that are effective against viral pathogens in CNS infections.

METHODS

A comprehensive literature search was conducted on scientific databases including: PubMed, Scopus, Google Scholar, and Web of Science. The relevant keywords used as search terms were: "myelitis", "encephalitis", "meningitis", "meningoencephalitis", "encephalomyelitis", "central nervous system", "brain", "spinal cord", "infection", "virus", "medicinal plants", and "biological compounds".

RESULTS

The most significant viruses involved in central nervous system infections are: Herpes Simplex Virus (HSV), Varicella Zoster Virus (VZV), West Nile Virus (WNV), Enterovirus 71 (EV71), Japanese Encephalitis Virus (JEV), and Dengue Virus (DENV). The inhibitory activity of medicinal plants against CNS viruses is mostly active through prevention of viral binding to cell membranes, blocking viral genome replication, prevention of viral protein expression, scavenging reactive Oxygen Species (ROS), and reduction of plaque formation.

CONCLUSION

Due to the increased resistance of microorganisms (bacteria, viruses, and parasites) to antimicrobial therapies, alternative treatments, especially using plant sources and their bioactive constituents, appear to be more fruitful.

Validation of Antidiabetic Potential of Gymnocarpos decandrus Forssk

Gymnocarpos decandrus Forssk. is a well-known grazing wild plant. This study targets scientific validation of its claimed antidiabetic activity and exploring its bioactive metabolites. Chromatographic purification of G. decandrus ethanol extract (GDEE) allowed isolation of vitexin (C1), protocatechuic acid (C2) and quercetin (C3). HPLC-PDA-MS/MS enabled identification of nineteen metabolites; 13 flavonoids, 5 saponins, and 1 phenolic acid in G. decandrus and four in the genus Gymnocarpos for the first time. The antidiabetic potential was evaluated via testing the Coxsackie B4 virus and α-glucosidase inhibitory potentials. C3 exhibited its potent antiviral activity through blocking of the virus attachment (96.28%, SI 4.41) and virus inactivation before adsorption (91.47%, SI 4.78). GDEE and C1-C3 showed dose dependent α-glucosidase inhibitory activity with IC₅₀ of 733.9, 293.3, 118.1 and 69.1 µg/mL, respectively. Our study represents the sole complete map for G. decandrus secondary metabolites and presents it as promising drug for diabetes management.

Inhibition of Herpes Simplex Viruses, Types 1 and 2, by Ginsenoside 20(S)-Rg3

Infections by herpes simplex viruses have an immense impact on humans, ranging from selflimiting, benign illness to serious, life-threatening diseases. While nucleoside analog drugs are available, resistance has been increasing and currently no vaccine exists. Ginsenosides derived from Panax ginseng have been documented to inhibit several viruses and bolster immune defenses. This study evaluated 12 of the most relevant ginsenosides from P. ginseng for toxicities and inhibition of herpes simplex viruses types 1 and 2 in Vero cells. The effects of test compounds and virus infection were determined using a PrestoBlue cell viability assay. Time course studies were also conducted to better understand at what points the virus life cycle was affected. Non-toxic concentrations of the ginsenosides were determined and ranged from 12.5 µM to greater than 100 µM. Ginsenoside 20(S)-Rg3 demonstrated the greatest inhibitory effect and was active against both HSV-1 and HSV-2 with an IC₅₀ of approximately 35 µM. The most dramatic inhibition-over 100% compared to controls-occurred when the virus was exposed to 20(S)-Rg3 for 4 h prior to being added to cells. 20(S)-Rg3 holds promise as a potential chemotherapeutic agent against herpes simplex viruses and, when used together with valacyclovir, may prevent increased resistance to drugs.

In Vitro Anti-Viral Effects of Small Heat Shock Proteins 20 and 27: A Novel Therapeutic Approach

BACKGROUND

The protective effects of heat shock proteins (Hsps) were studied in some infectious and non-infectious diseases, but their specificity was slightly known in various disorders. Among Hsps, small Hsps (e.g. Hsp27 and Hsp20) have important roles in protein folding and translocation, and also in immunity.

METHODS

In this study, overexpression of Hsp20 and Hsp27 was performed by transfection of the plasmids encoding Hsp20 and Hsp27 (pEGFP-Hsp20 and pEGFP-Hsp27) into Huh7.5, Hela and Vero cells using Lipofectamine along with heat shock. Then, their anti-herpes simplex virus-1 (HSV-1), anti- human immunodeficiency virus-1 (HIV-1) and anti-hepatitis C virus (HCV) effects, as well as cytotoxicity, were evaluated in vitro, for the first time.

RESULTS

Our data showed that simultaneous treatment with Lipofectamine and heat shock augmented the rate of transfection and subsequently the expression of Hsps in these cells. Moreover, overexpression of Hsp20 in HCV-infected Huh7.5 cells, HIV-infected Hela cells and HSV-infected Vero cells reduced the replication of HCV, HIV and HSV, respectively. In contrast, overexpression of Hsp27 significantly decreased HSV replication similar to Hsp20, but it did not affect the replication of HIV and HCV.

CONCLUSION

Generally, Hsp20 was identified as a novel anti-HCV, anti-HSV and anti-HIV agent, but Hsp27 was efficient in the suppression of HSV infection. These Hsps may act through suppression of virus entry and/ or through interaction with viral proteins. Thus, it is necessary to determine their exact mechanisms in the near future.

In vitro evaluation of anthraquinones from Aloe vera (Aloe barbadensis Miller) roots and several derivatives against strains of influenza virus

Aloe vera is a crop of wide economic value of worldwide distribution, and a rich source of quinone components. Recently, antiviral aloe anthraquinones had been reported against human influenza virus. In the present work two anthraquinones, aloesaponarin-I (1) and aloesaponarin-II (2) were isolated from A. vera roots, and six derivatives were obtained by methylation (3), acetylation (4) and O-glycosyl (5-6) reactions starting from (1). Additionally, a new Tetra-O-acetyl-β-d-glucopyranosyl derivative from 2 was also prepared. All compounds were evaluated against two strains of influenza virus AH1N1 by cytopathic effect reduction assay (CPE). The antiviral activity was determined by the ability of compounds to inhibit virus replication on Madin Darby Canine Kidney cells (MDCK). New derivatives 3-(2´,3´,4´,6´-Tetra-O-acetyl-β-d-glucopyranosyl-aloesaponarin-I (5) and 3-(2´,3´,4´,6´-Tetra-O-acetyl-β-d-glucopyranosyl- aloesaponarin-II (7) showed a cytopathic reduction effect against influenza strain A/Yucatán/2370/09 with IC50 of 30.77 and 13.70 μM, and against the virus A/Mexico/InDRE797/10 with IC50 of 62.28 and 19.47 μM, respectively. To assess the effect of derivatives 5 and 7 during one cycle of replication (0-10 h), a time-of-addition experiment was performed. As a result it was found that both compounds were most effective when added 6-10 h post-infection and significantly inhibited viral titre (> 70%) at the concentrations of 50 and 100 μM. Based on the structural analysis of the compounds, it was suggested that the Tetra-O-acetyl-β-d-glucopyranosyl substituent at the C3 position of the anthraquinone might have an effect against the influenza AH1N1 virus.

Evaluation of anti-HSV-1 activity and toxicity of hydroethanolic extract of Tanacetum parthenium (L.) Sch.Bip. (Asteraceae)

BACKGROUND

Herpes simplex type 1 (HSV-1) is widely distributed throughout the world's population. The virus spreads through direct contact with an infected individual. After primary infection, the virus remains in a latent state, and the recurrence of herpetic lesions is common. Standard treatment is performed with nucleoside analogues, but the selection of resistant strains have occurred, thus requiring the continual search for new antiviral agents. Plant extracts, fractions, and isolated compounds are a good source for studying possible antiviral compounds.

HYPOTHESIS

Among plants with antiviral activity, the crude extract of aerial parts of Tanacetum parthenium (L.) Sch.Bip. (Asteraceae) have previously shown to inhibit HSV-1 infection in vitro.

METHODS

The present study investigated the chemical composition of a crude hydroethanolic extract (CHE) of T. parthenium, and in vivo safety and therapeutic efficacy against HSV-1 infection.

RESULTS

Liquid chromatography-mass spectrometry showed that the CHE was composed of phenolic acids (chlorogenic acids) and sesquiterpene lactones (parthenolide). Acute and subchronic toxicity and genotoxicity tests in vivo showed that oral CHE administration did not result in signs of toxicity, with no genotoxic potential. The CHE was also safe for topical administration, in which no irritation of the epidermis was observed in treated animals. Tests of topical and oral therapeutic efficacy showed that the CHE was effective against HSV-1 infection. Topical administration was the most effective, the results for which were comparable to acyclovir.

CONCLUSION

These findings indicate that the CHE from aerial parts of Tanacetum parthenium has in vivo anti-HSV-1 activity and is safe for oral and topical application.

Asprellcosides B of Ilex asprella Inhibits Influenza A Virus Infection by Blocking the Hemagglutinin- Mediated Membrane Fusion

Ilex asprella is routinely used in China as a traditional medicinal herb to treat influenza (Flu). However, its specific antiviral activity and underlying molecular mechanism have not yet been determined. In this study, we sought to determine the antiviral activity and mechanism of Asprellcosides B, an active component extracted from Ilex asprella, and used against the influenza A virus cell culture. We also performed a computer-assisted structural modeling analysis and carried out surface plasmon resonance (SPR) experiments in the hope of determining the viral target of Asprellcosides B. Results from our studies show that Asprellcosides B reduced virus replication by up to 63% with an IC50 of about 9 μM. It also decreased the low pH-induced and virus-mediated hemolysis by 71% in vitro. Molecular docking simulation analysis suggested a possible binding of Asprellcosides B to the hemagglutinin (HA), which was confirmed by a surface plasmon resonance (SPR) assay. Altogether, our findings demonstrate that Asprellcosides B inhibits the influenza A virus, through a specific binding to the HA, resulting in the blockade of the HA-mediated membrane fusion.

Antiviral Evaluation of Herbal Drugs

The viral infection and resistance to the existing antiviral drugs are alarming, which is a serious public health concern. Medicinal plants are valuable resources for treatment of viral infections and can be used for the management of infections like herpes simplex virus (HSV), human immunodeficiency virus (HIV), influenza, etc. The antiviral screening of plant extracts should be highly selective, specific, and sensitive for bioactivity guided isolation of the active compounds from the plant extracts. The antiviral screening system should be validated for accuracy, reproducibility, simplicity, and cost effectiveness. This chapter highlights on various aspects for screening and evaluation of antiviral natural components including factors affecting antiviral in vivo studies, host cells, organisms, and culture media followed by different virus-specific assays for antiviral screening of natural products.

Anti-Adenoviral Activity of 2-(3-Chlorotetrahydrofuran-2-yl)-4-Tosyl-5-(Perfluoropropyl)-1,2,3-Triazole

Background and objectives: A considerable increase in the levels of adenoviral diseases among both adults and children necessitate the development of effective methods for its prevention and treatment. The synthesis of the new fluorinated 1,2,3-triazoles, and the study of the mechanisms of their action, are promising for the development of efficient antiviral drugs of our time. Materials and Methods: Antiviral activity and cell cytotoxic effect of 2-(3-chlorotetrahydrofuran-2-yl)-4-tosyl-5-(perfluoropropyl)-1,2,3-triazole (G29) were determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The influence of the compound on the infectivity of human adenovirus type 5 (HAdV-5) was carried out via the cytomorphology method. The influence of the compound on the cell cycle under a condition of adenovirus infection was studied using flow cytometric analysis of propidium iodide-stained cells. Results: It was found that G29 suppressed HAdV-5 reproduction by 50% in concentrations of 37 μg/mL. Furthermore, the compound reduced the titer of virus obtained de novo, and inhibited HAdV-5 inclusion bodies formation by 84–90%. The use of fluorinated compounds under the conditions of adenovirus infection decreased the number of apoptotic cells by 11% and the number of cells in S phase by 21–42% compared to the profile of infected cells. Conclusions: The fluorinated compound G29 showed moderate activity against HAdV-5 based on several mechanisms. It led to the normalization of the life cycle of cells infected with adenovirus to the level of non-infected cells and caused the obstruction of HAdV-5 reproduction, inducing the formation of non-infectious virus progeny.

Immunomodulatory properties of quercetin-3-O-α-L-rhamnopyranoside from Rapanea melanophloeos against influenza a virus

BACKGROUND

Influenza infection is a major public health threat. The role of influenza A virus-induced inflammatory response in severe cases of this disease is widely recognized. Drug resistance and side effects of chemical treatments have been observed, resulting in increased interest in alternative use of herbal medications for prophylaxis against this infection. The South African medicinal plant, Rapanea melanophloeos (RM) (L.) Mez of the family Myrsinaceae was selected owing to its traditional use for the treatment of several diseases such as respiratory ailments and also previous preliminary studies of anti-influenza activity of its methanolic extract. The aim of this study was to investigate the immunomodulatory properties of a glycoside flavone isolated from RM against influenza A virus.

METHODS

The non-cytotoxic concentration of the quercetin-3-O-α-L-rhamnopyranoside (Q3R) was determined by MTT assay and tested for activity against influenza A virus (IAV) in simultaneous, pre-penetration and post-penetration combination treatments over 1 h incubation on MDCK cells. The virus titer and viral load targeting NP and M2 viral genes were determined using HA and qPCR, respectively. TNF-α and IL-27 as pro- and anti-inflammatory cytokines were measured at RNA and protein levels by qPCR and ELISA, respectively.

RESULTS

Quercetin-3-O-α-L-rhamnopyranoside at 150 μg/ml decreased the viral titer by 6 logs (p < 0.01) in the simultaneous procedure. The NP and M2 genes copy numbers as viral target genes, calculated based on the Ct values and standard formula, significantly decreased in simultaneous treatment (p < 0.01). The expression of cytokines was also considerably affected by the compound treatment.

CONCLUSIONS

This is the first report of quercetin-3-O-α-L-rhamnopyranoside from RM and its immunomodulatory properties against influenza A virus. Further research will focus on detecting the specific mechanism of virus-host interactions.

A comprehensive review of phytochemical profile, bioactives for pharmaceuticals, and pharmacological attributes of Azadirachta indica

Azadirachta indica L. is a multipurpose medicinal tree of family Meliaceae. It occurs in tropical and semitropical regions of the world. Different parts of this miraculous tree are used to treat pyrexia, headache, ulcer, respiratory disorders, cancer, diabetes, leprosy, malaria, dengue, chicken pox, and dermal complications. The tree is popular for its pharmacological attributes such as hypolipidemic, antifertility, microbicidal, antidiabetic, anti-inflammatory, hepatoprotective, antipyretic, hypoglycemic, insecticidal, nematicidal, antiulcer, antioxidant, neuroprotective, cardioprotective, and antileishmaniasis properties. A. indica is also rich in various phytochemicals for pharmaceuticals such as alkaloids, steroids, flavonoids, terpenoids, fatty acids, and carbohydrates. The fungicidal potential of the tree is due to the presence of azadirachtin and nimbin. Herein, we have compiled a comprehensive review of phytochemical profile, pharmacological attributes, and therapeutic prospective of this multipurpose tree.

South African medicinal plant extracts active against influenza A virus

BACKGROUND

Influenza infection remains a major health threat for animals and humans which crucially requires effective antiviral remedies. The usage of herbal medications as readily available alternatives for their compatibility with the body and fewer side effects compared to synthetic chemical treatments has become popular globally. The aim of this study was to investigate and screen in vitro anti-influenza activity of extracts of five South African medicinal plants, namely Tabernaemontana ventricosa, Cussonia spicata, Rapanea melanophloeos, Pittosporum viridiflorum and Clerodendrum glabrum, species which are used traditionally for the treatment of several diseases such as inflammatory and respiratory diseases.

METHODS

Methanol, ethanol (100% and 30%), acetone, hot and cold water extracts of the powdered plants leaves were obtained by standard methods. The cytotoxicity was determined by the MTT colorimetric assay on MDCK cells. The concentrations below CC₅₀ values were tested for antiviral activity against influenza A virus (IAV) in different combination treatments. The effect of extracts on viral surface glycoproteins and viral titer were tested by HI and HA virological assays, respectively.

RESULTS

Based on the applied methods, the most effective results against IAV were obtained from Rapanea melanophloeos methanol leaf extract (EC₅₀ = 113.3 μg/ml) and Pittosporum viridiflorum methanol, 100% and 30% ethanol and acetone leaf extracts (EC₅₀ values = 3.6, 3.4, 19.2, 82.3 μg/ml, respectively) in all types of combined treatments especially in pre- and post-penetration combined treatments with highly significant effects against viral titer (P ≤ 0.01).

CONCLUSION

The outcomes offer for the first time a scientific basis for the use of extracts of Rapanea melanophloeos and Pittosporum viridiflorum against IAV. It is worth focusing on the isolation and identification of effective active compounds and elucidating the mechanism of action from these species. However, Tabernaemontana ventricosa, Cussonia spicata and Clerodendrum glabrum leaf extracts were ineffective in vitro in this study.

Baicalin is an inhibitor of subgroup J avian leukosis virus infection

Avian leukosis virus subgroup J (ALV-J) can cause great economic losses to the poultry industry worldwide. Baicalin, one of the flavonoids present in S.baicalensis Georgi, has been shown to have antiviral activities. To investigate whether baicalin has antiviral effects on the infection of ALV-J in DF-1 cells, the cells were treated with baicalin at different time points. We found that baicalin could inhibit viral mRNA, protein levels and overall virus infection in a dose- and time-dependent manner using a variety of assays. Baicalin specifically targeted virus internalization and reduced the infectivity of ALV-J particles, but had no effect on the levels of major ALV-J receptor and virus binding to DF-1 cells. Collectively, these results suggest that baicalin might have potential to be developed as a novel antiviral agent for ALV-J infection.

Cytotoxicity and anti-Sporothrix brasiliensis activity of the Origanum majorana Linn. oil

The study aimed to evaluate the anti-Sporothrix sp. activity of the essential oil of Origanum majorana Linn. (marjoram), its chemical analysis, and its cytotoxic activity. A total of 18 fungal isolates of Sporothrix brasiliensis (n: 17) from humans, dogs and cats, and a standard strain of Sporothrix schenckii (n: 1) were tested using the broth microdilution technique (Clinical and Laboratory Standard Institute – CLSI M27-A3) and the results were expressed in minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC). The MIC₅₀ and MIC₉₀ of itraconazole against S. brasiliensis were 2 μg/mL and 8 μg/mL, respectively, and the MFC₅₀ and MFC₉₀ were 2 μg/mL and >16 μg/mL, respectively, with three S. brasiliensis isolates resistant to antifungal. S. schenckii was sensitive at MIC of 1 μg/mL and MFC of 8 μg/mL. For the oil of O. majorana L., all isolates were susceptible to MIC of ≤2.25–9 mg/mL and MFC of ≤2.25–18 mg/mL. The MIC₅₀ and MIC₉₀ were ≤2.25 mg/mL and 4.5 mg/mL, respectively, and the MFC_50/90 values were twice more than the MIC. Twenty-two compounds were identified by gas chromatography with a flame ionization detector (CG-FID) and 1,8-cineole and 4-terpineol were the majority. Through the colorimetric (MTT) assay, the toxicity was observed in 70–80% of VERO cells between 0.078 and 5 mg/mL. For the first time, the study demonstrated the satisfactory in vitro anti-Sporothrix sp. activity of marjoram oil and further studies are needed to ensure its safe and effective use.

Computational analysis reveal inhibitory action of nimbin against dengue viral envelope protein

Dengue has emerged to be global health problem worldwide. Hence there is an immediate need to adopt new strategies in the development of effective anti-dengue drugs. Extracts from the leaves of Azadirachta indica has been traditionally used in folk medicine for viral infections. In the present study we report the anti-viral potency of nimbin, the active compound from the neem leaf extract against the envelope protein of dengue virus. Progression of viral entry into the host cell is facilitated by the envelope protein of dengue virus, suggesting; it as an effective anti-viral target. Nimbin is found to be effective against the envelope protein of all four types of dengue virus (dengue 1-4), which is evident from our in silico analysis. Our findings suggest the clinical importance of nimbin, which can serve as effective lead compound for further analysis.

Anti-herpetic and anti-dengue activity of abietane ferruginol analogues synthesized from (+)-dehydroabietylamine

The abietane-type diterpenoid (+)-ferruginol (1), a bioactive compound isolated from several plants, has attracted much attention as consequence of its pharmacological properties, which includes antibacterial, antifungal, antimicrobial, cardioprotective, anti-oxidative, anti-plasmodial, leishmanicidal, anti-ulcerogenic, anti-inflammatory and antitumor actions. In this study, we report on the antiviral evaluation of ferruginol (1) and several analogues synthesized from commercial (+)-dehydroabietylamine. Thus, the activity against Human Herpesvirus type 1, Human Herpesvirus type 2 and Dengue Virus type 2, was studied. Two ferruginol analogues showed high antiviral selectivity index and reduced viral plaque-size in post-infection stages against both Herpes and Dengue viruses. A promising lead, compound 8, was ten-fold more potent (EC50 = 1.4 μM) than the control ribavirin against Dengue Virus type 2. Our findings suggest that the 12-hydroxyabieta-8,11,13-triene skeleton, which is characteristic of the diterpenoid ferruginol (1), is an interesting molecular scaffold for development of novel antivirals. In addition, the cytotoxic and antifungal activities of the synthesized ferruginol analogues have also been investigated. (©)20155 Elsevier Science. All rights reserved.

Validation of Antiviral Potential of Herbal Ethnomedicine

Natural products are the basis of treatment since the dawn of human civilization, and modern medicine has gradually developed, over the years, by scientific and observational efforts from traditional medicine. Today most of the synthetic drugs showed adverse and unacceptable side effects, however, impressive bioactivities with reduced toxicities were reported for many botanicals against several chronic or difficult-to-treat diseases. A whole range of viral diseases including human immunodeficiency virus/acquired immunodeficiency syndrome, severe acute respiratory syndrome, Rabies, Dengue, and Herpes need effective drugs. Considerable research has been carried out on the pharmacognosy, chemistry, pharmacology, and therapeutics of traditional medicines of diverse cultures, and many pharmaceutical companies have renewed their strategies for antiviral drug development where no effective drugs or vaccine exist. Thus, phytochemicals with antiviral potentials need to be studied in depth with standardization, chemical isolation, effectivity, molecular mechanism, along with in vivo toxicity and efficacy to reduce cost and time. This review will portray the scientific approaches and methodologies used for the development of antiviral leads from traditional medicines against selected genetically and functionally diverse viral infections.