Identification of potential ZIKV NS2B-NS3 protease inhibitors from Andrographis paniculata: An insilico approach.

Andrographis paniculata is a widely used medicinal plant for treating a variety of human infections. The plant's bioactives have been shown to have a variety of biological activities in various studies, including potential antiviral, anticancer, and anti-inflammatory effects in a variety of experimental models. The present investigation identifies a potent antiviral compound from the phytochemicals of Andrographis paniculata against Zika virus using computational docking simulation. The ZIKV NS2B-NS3 protease, which is involved in viral replication, has been considered as a promising target for Zika virus drug development. The bioactives from Andrographis paniculata, along with standard drugs as control were screened for their binding energy using AutoDock 4.2 against the viral protein. Based on the higher binding affinity the phytocompounds Bisandrographolide A (-11.7), Andrographolide (-10.2) and Andrographiside (-9.7) have convenient interactions at the binding site of target protein (ZIKV NS2B-NS3 protease) in comparison with the control drug. In addition, using insilico tools, the selected high-scoring molecules were analysed for pharmacological properties such as ADME (Absorption, Distribution, Metabolism, and Excretion profile) and toxicity. Andrographolide was reported to have strong pharmacodynamics properties and target accuracy based on the Lipinski rule and lower binding energy. The selected bioactives showed lower AMES toxicity and has potent antiviral activity against zika virus targets. Further, MD simulation studies validated Bisandrographolide A & Andrographolide as a potential hit compound by exhibiting good binding with the target protein. The compounds exhibited good hydrogen bonds with ZIKV NS2B-NS3 protease. As a result, bioactives from the medicinal plant Andrographis paniculata can be studied in vitro and in vivo to develop an antiviral phytopharmaceutical for the successful treatment of zika virus.Communicated by Ramaswamy H. Sarma.

Bruguiera gymnorhiza (L.) Lam. at the Forefront of Pharma to Confront Zika Virus and Microbial Infections-An In Vitro and In Silico Perspective.

The recent emergence of Zika virus (ZIKV) in Brazil and the increasing resistance developed by pathogenic bacteria to nearly all existing antibiotics should be taken as a wakeup call for the international authority as this represents a risk for global public health. The lack of antiviral drugs and effective antibiotics on the market triggers the need to search for safe therapeutics from medicinal plants to fight viral and microbial infections. In the present study, we investigated whether a mangrove plant, Bruguiera gymnorhiza (L.) Lam. (B. gymnorhiza) collected in Mauritius, possesses antimicrobial and antibiotic potentiating abilities and exerts anti-ZIKV activity at non-cytotoxic doses. Microorganisms Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 70603, methicillin-resistant Staphylococcus aureus ATCC 43300 (MRSA), Salmonella enteritidis ATCC 13076, Sarcina lutea ATCC 9341, Proteus mirabilis ATCC 25933, Bacillus cereus ATCC 11778 and Candida albicans ATCC 26555 were used to evaluate the antimicrobial properties. Ciprofloxacin, chloramphenicol and streptomycin antibiotics were used for assessing antibiotic potentiating activity. ZIKVMC-MR766NIID (ZIKVGFP) was used for assessing anti-ZIKV activity. In silico docking (Autodock 4) and ADME (SwissADME) analyses were performed on collected data. Antimicrobial results revealed that Bruguiera twig ethyl acetate (BTE) was the most potent extract inhibiting the growth of all nine microbes tested, with minimum inhibitory concentrations ranging from 0.19-0.39 mg/mL. BTE showed partial synergy effects against MRSA and Pseudomonas aeruginosa when applied in combination with streptomycin and ciprofloxacin, respectively. By using a recombinant ZIKV-expressing reporter GFP protein, we identified both Bruguiera root aqueous and Bruguiera fruit aqueous extracts as potent inhibitors of ZIKV infection in human epithelial A549 cells. The mechanisms by which such extracts prevented ZIKV infection are linked to the inability of the virus to bind to the host cell surface. In silico docking showed that ZIKV E protein, which is involved in cell receptor binding, could be a target for cryptochlorogenic acid, a chemical compound identified in B. gymnorhiza. From ADME results, cryptochlorogenic acid is predicted to be not orally bioavailable because it is too polar. Scientific data collected in this present work can open a new avenue for the development of potential inhibitors from B. gymnorhiza to fight ZIKV and microbial infections in the future.

The Compound SBI-0090799 Inhibits Zika Virus Infection by Blocking De Novo Formation of the Membranous Replication Compartment.

Zika virus (ZIKV) is a mosquito-borne pathogen classified by the World Health Organization (WHO) as a public health emergency of international concern in 2016, and it is still identified as a priority disease. Although most infected individuals are asymptomatic or show mild symptoms, a risk of neurologic complications is associated with infection in adults. Additionally, infection during pregnancy is directly linked to microcephaly and other congenital malformations. Since there are no currently available vaccines or approved therapeutics for this virus, there is a critical unmet need in developing treatments to prevent future ZIKV outbreaks. Toward this end, we performed a large-scale cell-based high-content screen of 51,520 chemical compounds to identify potential antiviral drug candidates. The compound (2E)-N-benzyl-3-(4-butoxyphenyl)prop-2-enamide (SBI-0090799) was found to inhibit replication of multiple ZIKV strains and in different cell systems. SBI-0090799 did not affect viral entry or RNA translation but suppressed RNA replication by preventing the formation of the membranous replication compartment. Selection of drug-resistant viruses identified single-amino-acid substitutions in the N-terminal region of nonstructural protein NS4A, arguing this is the likely drug target. These resistance mutations rescued viral RNA replication and restored the formation of the membranous replication compartment. This mechanism of action is similar to clinically approved NS5A inhibitors for hepatitis C virus (HCV). Taken together, SBI-0090799 represents a promising lead candidate for the development of an antiviral treatment against ZIKV infection for the mitigation of severe complications and potential resurgent outbreaks of the virus. IMPORTANCE This study describes the elucidation of (2E)-N-benzyl-3-(4-butoxyphenyl)prop-2-enamide (SBI-0090799) as a selective and potent inhibitor of Zika virus (ZIKV) replication using a high-throughput screening approach. Mapping and resistance studies, supported by electron microscopy observations, indicate that the small molecule is functioning through inhibition of NS4A-mediated formation of ZIKV replication compartments in the endoplasmic reticulum (ER). Intriguingly, this defines a novel nonenzymatic target and chemical matter for the development of a new class of ZIKV antivirals. Moreover, chemical modulation affecting this nonstructural protein mirrors the identification and development of hepatitis C virus (HCV) NS5A inhibitor daclatasvir and its derivatives, similarly interfering with the formation of the viral replication compartment and also targeting a protein with no enzymatic activity, which have been part of a curative strategy for HCV.

Therapeutic targets and biological mechanisms of action of curcumin against Zika virus: In silico and in vitro analyses.

Zika virus (ZIKV) is a mosquito-borne flavivirus, that could cause congenital Zika syndrome (CZS), characterized by microcephaly, neurological complications and fetal deaths. No specific treatments for ZIKV are currently available, highlighting the urgent global need to identify and develop therapeutic agents. Drug repositioning of approved natural compounds can provide effective alternative solutions for novel antiviral development. The current study focused on curcumin, a component of turmeric known to exert diverse antiviral effects. We integrated in silico information from publicly available databases to predict interactions between curcumin and potential targets of ZIKV. In our network analysis, we identified four targets, TP53, AKT1, PTEN, and TNF, which were identified as potential targets associated with ZIKV. Based on retrieved targets, we performed molecular docking study and identified curcumin-TNF showed the strongest binding among four targets. The anti-Zika effects of curcumin were validated in vitro with the aid of antiviral and plaque reduction assay. Curcumin at concentrations ranging from 12.5 to 50 µM displayed significant antiviral activity in a dose-dependent manner (p < 0.05). In view of its natural abundance and prevalence in the human diet, curcumin holds significant promise for treatment of ZIKV infections.

In vitro study of Hesperetin and Hesperidin as inhibitors of zika and chikungunya virus proteases.

The potential outcome of flavivirus and alphavirus co-infections is worrisome due to the development of severe diseases. Hundreds of millions of people worldwide live under the risk of infections caused by viruses like chikungunya virus (CHIKV, genus Alphavirus), dengue virus (DENV, genus Flavivirus), and zika virus (ZIKV, genus Flavivirus). So far, neither any drug exists against the infection by a single virus, nor against co-infection. The results described in our study demonstrate the inhibitory potential of two flavonoids derived from citrus plants: Hesperetin (HST) against NS2B/NS3pro of ZIKV and nsP2pro of CHIKV and, Hesperidin (HSD) against nsP2pro of CHIKV. The flavonoids are noncompetitive inhibitors and the determined IC50 values are in low µM range for HST against ZIKV NS2B/NS3pro (12.6 ± 1.3 µM) and against CHIKV nsP2pro (2.5 ± 0.4 µM). The IC50 for HSD against CHIKV nsP2pro was 7.1 ± 1.1 µM. The calculated ligand efficiencies for HST were > 0.3, which reflect its potential to be used as a lead compound. Docking and molecular dynamics simulations display the effect of HST and HSD on the protease 3D models of CHIKV and ZIKV. Conformational changes after ligand binding and their effect on the substrate-binding pocket of the proteases were investigated. Additionally, MTT assays demonstrated a very low cytotoxicity of both the molecules. Based on our results, we assume that HST comprise a chemical structure that serves as a starting point molecule to develop a potent inhibitor to combat CHIKV and ZIKV co-infections by inhibiting the virus proteases.

Himatanthus bracteatus stem extracts present anti-flavivirus activity while an isolated sesquiterpene glucoside present only anti-Zika virus activity in vitro.

The hexane and ethanol extracts from Himatanthus bracteatus (Apocynaceae) stems were evaluated for antiviral activity against Zika virus, yellow fever virus and dengue virus 2 and for cytotoxicity in Vero cells by MTT assay. The ethanol extract showed good antiviral activity against the three viruses with selective indexes (SI) > 10 and its fractionation led to the isolation of the known plumieride that was active only against Zika virus (SI of 15.97).

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.

Therapeutic candidates for the Zika virus identified by a high-throughput screen for Zika protease inhibitors.

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Harringtonine Inhibits Zika Virus Infection through Multiple Mechanisms.

Mosquito-borne Zika virus (ZIKV) is a Flavivirus that came under intense study from 2014 to 2016 for its well-known ability to cause congenital microcephaly in fetuses and neurological Guillain-Barré disease in adults. Substantial research on screening antiviral agents against ZIKV and preventing ZIKV infection are globally underway, but Food and Drug Administration (FDA)-approved treatments are not available yet. Compounds from Chinese medicinal herbs may offer an opportunity for potential therapies for anti-ZIKV infection. In this study, we evaluated the antiviral efficacy of harringtonine against ZIKV. Harringtonine possessed anti-ZIKV properties against the binding, entry, replication, and release stage through the virus life cycle. In addition, harringtonine have strong virucidal effects in ZIKV and exhibited prophylaxis antiviral ability prior ZIKV infection. The antiviral activity also observed in the treatment against Japanese encephalitis reporter virus (RP9-GFP strain). Overall, this study demonstrated that harringtonine would be a favorable potential candidate for the development of anti-ZIKV infection therapies.

Anti-Zika virus activity and chemical characterization by ultra-high performance liquid chromatography (UPLC-DAD-UV-MS) of ethanol extracts in Tecoma species.

BACKGROUND: Plant species from the genus Tecoma are found in tropical and subtropical regions around the world. Some of them are grown as ornamental plants and others can be used as medicinal plants. In the present study, ethanolic extracts from trunks and leaves of Tecoma species were tested in vitro using assays against the Zika virus. METHODS: There was a total of 8 extracts obtained from different anatomical parts of three Tecoma species. The Tecoma castaneifolia, T. garrocha, T. stans var. angustata and T. stans var. stans were prepared by percolation with ethanol. The antiviral activity was assayed in vitro against the Zika virus by the MTT colorimetric method (n = 3). The UPLC-DAD-MS analysis of ethanolic extracts was performed from all the studied species. The biofractionation of T. stans var. stans trunk extract using different separation techniques led to the isolation of crenatoside compound. RESULTS: Ethanolic extract from Tecoma species leaves were more active against the Zika virus (EC50 149.90 to 61.25 µg/mL) when compared to the trunk extracts tested (EC50 131.0 to 66.79 µg/mL and two were not active). The ethyl acetate and aqueous fractions obtained from T. stans var. stans trunk were active against the Zika virus with EC50 values of 149.90 and 78.98 µg/mL, respectively. Crenatoside is a phenylethanoid glycoside isolated from the ethyl acetate of T. stans var. stans trunk extract. This compound was tested and exhibited EC50 34.78 µM (21.64 µg/mL), thus demonstrating a better result than the original ethanolic extracts as well as others extracts of Tecoma species, and it was more active than the positive control, ribavirin (386.84 µM). Furthermore, its selectivity index was at least 2.5 times higher than the tested ethanolic extracts and 11.1 times more potent than ribavirin. CONCLUSION: The Tecoma species demonstrated interesting in vitro activity against the Zika virus. The crenatoside, phenylethanoid glycoside that was for the first time isolated from Tecoma stans var. stans, exhibited a potent and relevant anti-Zika virus activity, being more active than ribavirin (positive control). The data show that crenatoside, was a promising compound with in vitro antiviral activity against the Zika virus.

Future and Perspectives of the Zika Virus: Drug Repurposing as a Powerful Tool for Treatment Insights.

The Zika virus (ZIKV) infection is a major public health concern in Brazil and worldwide, being a rapidly spreading disease with possible severe complications for pregnant women and neonates. There is currently no preventative therapy or specific treatment available. Within this context, drug repositioning is a very promising approach for the discovery of new treatment compounds, since old drugs may become new ones. Therefore, this paper aims to perform a literature mini-review to identify promising compounds to combat this virus. The mechanism of action at the molecular level and the structure-activity relationship of prototypes are discussed. Among the candidates identified, we highlight sofosbuvir, chloroquine and suramin, which present a greater quantity of experimental data to draw on for our discussion. The current treatment is palliative; therefore, this study is of paramount importance in identifying drug candidates useful for combating ZIKV.

Antiviral effect of silymarin against Zika virus in vitro.

Zika virus (ZIKV) epidemic and its association with severe neurological syndromes have raised worldwide concern. Despite the great clinical relevance of this infection, no vaccine or specific treatment is available and the search for antiviral compounds against ZIKV is extremely necessary. Several natural compounds, such as silymarin, exhibit antioxidant, hepatoprotective, and antiviral properties; however, the antiviral potential of this compound remains partially investigated. Therefore, the objective of this study was to evaluate in vitro the antiviral activity of silymarin against ZIKV infection. Global antiviral activity, dose-dependent, plaque reduction, and time-of-drug-addition assays were used to determine the anti-ZIKV activity of silymarin. Additionally, to start characterizing the mechanisms of action we determined whether silymarin could have a virucidal effect and inhibit viral adsorption and penetration stages. Regarding its global antiviral activity, silymarin showed significant inhibition of ZIKV infection, protecting cells infected with EC50 equal to 34.17µg/mL, with a selectivity index greater than 17 and 4x greater than that of the positive control (ribavirin). Its greatest efficiency was achieved at 125µg/mL, whose cell viability did not differ from the control without infection and treatment. Furthermore, treatment with silymarin reduced viral load by up to two logs (> 90%) concerning viral control, when evaluating virucidal activity and the precocious times of infection. Thus, our results set to show the promising anti-ZIKV activity of silymarin, which does not seem to have a single inhibition mechanism, acting at different times of infection, and still has the advantage of silymarin be a phytotherapy already available on the market.

Xanthenedione (and intermediates involved in their synthesis) inhibit Zika virus migration to the central nervous system in murine neonatal models.

Zika Virus (ZIKV), an arbovirus that belongs to the Flaviviridae family, has become a global concern since its outbreak in the Americas in 2015. With symptoms similar to other Flavivirus as Dengue and Yellow Fever viruses, infections by ZIKV have also been related to several neurological complications such as microcephaly in newborns and Guillain-Barre syndrome. Considering the high prevalence of ZIKV infection in certain areas, the risks that the virus poses to fetal brain development, and the fact that there is no vaccine or specific prophylaxis available, an effective treatment capable of preventing the infection is of potential interest. Therefore, in the present investigation, the antiviral activity on ZIKV of a group of xanthenodiones and intermediate ketones involved in their synthesis was evaluated for the first time. It was found that the compound 2-(2,6-dichlorobenzylidene)cyclohexane-1,3-dione 27 was able to completely inhibit the viral infection of Vero cells as well as to significantly reduce viral load in the brains of newborn Swiss mice. These effects are related to a direct interaction of the compound with the viral particle, blocking the viral adsorption.

In vitro Studies on The Inhibition of Replication of Zika and Chikungunya Viruses by Dolastane Isolated from Seaweed Canistrocarpus cervicornis.

The lack of vaccines and antiviral treatment, along with the increasing number of cases of Zika virus (ZIKV) and Chikungunya virus (CHIKV) infections, emphasize the need for searching for new therapeutic strategies. In this context, the marine brown seaweed Canistrocarpus cervicornis has been proved to hold great antiviral potential. Hence, the aim of this work was to evaluate the anti-ZIKV and anti-CHIKV activity of a marine dolastane isolated from brown seaweed C. cervicornis and its crude extract. Vero cells were used in antiviral assays, submitted to ZIKV and CHIKV, and treated with different concentrations of C. cervicornis extract or dolastane. The crude extract of C. cervicornis showed inhibitory activities for both ZIKV and CHIKV, with EC50 values of 3.3 µg/mL and 3.1 µg/mL, respectively. However, the isolated dolastane showed a more significant and promising inhibitory effect (EC50 = 0.95 µM for ZIKV and 1.3 µM for CHIKV) when compared to both the crude extract and ribavirin, which was used as control. Also, the dolastane showed a very potent virucidal activity against CHIKV and was able to inhibit around 90% of the virus infectivity at 10 µM. For the ZIKV, the effects were somewhat lower, although interesting, at approximately 64% in this same concentration. Further, we observed that both the extract and the dolastane were able to inhibit the replication of ZIKV and CHIKV at different times of addition post-infection, remaining efficient even if added after 8 hours post-infection, but declining soon after. A synergistic effect using sub-doses of the extract and isolates was associated with ribavirin, inhibiting above 80% replication even at the lowest concentrations. Therefore, this work has unveiled the anti-ZIKV and CHIKV potential of C. cervicornis crude extract and an isolated dolastane, which, in turn, can be used as a preventive or therapeutic strategy in the future.

The Geraniin-Rich Extract from Reunion Island Endemic Medicinal Plant Phyllanthus phillyreifolius Inhibits Zika and Dengue Virus Infection at Non-Toxic Effect Doses in Zebrafish.

The mosquito-borne viruses dengue (DENV) and Zika (ZIKV) viruses are two medically important pathogens in tropical and subtropical regions of the world. There is an urgent need of therapeutics against DENV and ZIKV, and medicinal plants are considered as a promising source of antiviral bioactive metabolites. In the present study, we evaluated the ability of Phyllanthus phillyreifolius, an endemic medicinal plant from Reunion Island, to prevent DENV and ZIKV infection in human cells. At non-cytotoxic concentration in vitro, incubation of infected A549 cells with a P. phillyreifolius extract or its major active phytochemical geraniin resulted in a dramatic reduction of virus progeny production for ZIKV as well as four serotypes of DENV. Virological assays showed that P. phillyreifolius extract-mediated virus inhibition relates to a blockade in internalization of virus particles into the host cell. Infectivity studies on ZIKV showed that both P. phillyreifolius and geraniin cause a loss of infectivity of the viral particles. Using a zebrafish model, we demonstrated that administration of P. phillyreifolius and geraniin has no effect on zebrafish locomotor activity while no morbidity nor mortality was observed up to 5 days post-inoculation. Thus, P. phillyreifolius could act as an important source of plant metabolite geraniin which is a promising antiviral compound in the fight against DENV and ZIKV.

Identification of a Potential Zika Virus Inhibitor Targeting NS5 Methyltransferase Using Virtual Screening and Molecular Dynamics Simulations.

The NS5 methyltransferase (MTase) has been reported as an attractive molecular target for antivirals discovery against the Zika virus (ZIKV). Here, we report structure-based virtual screening of 42 390 structures from the Development Therapeutics Program (DTP) AIDS Antiviral Screen Database. Among the docked compounds, ZINC1652386 stood out due to its high affinity for MTase in comparison to the cocrystallized ligand MS2042, which interacts with the Asp146 residue in the MTase binding site by hydrogen bonding. Subsequent molecular dynamics simulations predicted that this compound forms a stable complex with MTase within 50 ns. Thus, ZINC1652386 may represent a promising ZIKV methyltransferase inhibitor.

Potential neuroprotective and anti-inflammatory effects provided by omega-3 (DHA) against Zika virus infection in human SH-SY5Y cells.

Zika virus (ZIKV) has a strong tropism for the nervous system and has been related to post-infection neurological syndromes. Once neuronal cells are infected, the virus is capable of modulating cell metabolism, leading to neurotoxicity and cellular death. The negative effect of ZIKV in neuron cells has been characterized. However, the description of molecules capable of reversing these cytotoxic effects is still under investigation. In this context, it has been largely demonstrated that docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid, is highly neuroprotective. Here, we hypothesized that DHA's neuroprotective proprieties could have an influence on ZIKV-induced neurotoxicity in SH-SY5Y cells. Our data showed that pre-treatment of SH-SY5Y cells with DHA increased the cell viability and proliferation in ZIKV-infected cells. Moreover, DHA triggered an anti-inflammatory response in those infected cells. Besides, DHA was capable of restoring mitochondria function and number in ZIKV-infected SH-SY5Y cells. In addition, cells pre-treated with DHA prior to ZIKV infection presented a lower viral load at different times of infection. Taking together, these results demonstrated that DHA has a potential anti-inflammatory and neuroprotective effect against ZIKV infection in these neuron-like cells and could be a useful tool in the treatment against this virus.

Resveratrol affects Zika virus replication in vitro.

Zika virus (ZIKV) infection is a serious public health concern. ZIKV infection has been associated with increased occurrences of microcephaly among newborns and incidences of Guillain-Barré syndrome among adults. No specific therapeutics or vaccines are currently available to treat and protect against ZIKV infection. Here, a plant-secreted phytoalexin, resveratrol (RES), was investigated for its ability to inhibit ZIKV replication in vitro. Several RES treatment regimens were used. The ZIKV titers of mock- and RES-treated infected cell cultures were determined using the focus-forming assay and the Zika mRNA copy number as determined using qRT-PCR. Our results suggested that RES treatment reduced ZIKV titers in a dose-dependent manner. A reduction of >90% of virus titer and ZIKV mRNA copy number was achieved when infected cells were treated with 80 µM of RES post-infection. Pre-incubation of the virus with 80 µM RES showed >30% reduction in ZIKV titers and ZIKV mRNA copy number, implying potential direct virucidal effects of RES against the virus. The RES treatment reduced >70% virus titer in the anti-adsorption assay, suggesting the possibility that RES also interferes with ZIKV binding. However, there was no significant decrease in ZIKV titer when a short-period of RES treatment was applied to cells before ZIKV infection (pre-infection) and after the virus bound to the cells (virus internalization inhibition), implying that RES acts through its continuous presence in the cell cultures after virus infection. Overall, our results suggested that RES exhibited direct virucidal activity against ZIKV and possessed anti-ZIKV replication properties, highlighting the need for further exploration of RES as a potential antiviral molecule against ZIKV infection.

Ayapana triplinervis Essential Oil and Its Main Component Thymohydroquinone Dimethyl Ether Inhibit Zika Virus at Doses Devoid of Toxicity in Zebrafish.

Zika virus (ZIKV) is an emerging mosquito-borne virus of medical concern. ZIKV infection may represent a serious disease, causing neonatal microcephaly and neurological disorders. Nowadays, there is no approved antiviral against ZIKV. Several indigenous or endemic medicinal plants from Mascarene archipelago in Indian Ocean have been found able to inhibit ZIKV infection. The purpose of our study was to determine whether essential oil (EO) from Reunion Island medicinal plant Ayapana triplinervis, whose thymohydroquinone dimethyl ether (THQ) is the main component has the potential to prevent ZIKV infection in human cells. Virological assays were performed on human epithelial A549 cells infected with either GFP reporter ZIKV or epidemic viral strain. Zebrafish assay was employed to evaluate the acute toxicity of THQ in vivo. We showed that both EO and THQ inhibit ZIKV infection in human cells with IC50 values of 38 and 45 µg/mL, respectively. At the noncytotoxic concentrations, EO and THQ reduced virus progeny production by 3-log. Time-of-drug-addition assays revealed that THQ could act as viral entry inhibitor. At the antiviral effective concentration, THQ injection in zebrafish does not lead to any signs of stress and does not impact fish survival, demonstrating the absence of acute toxicity for THQ. From our data, we propose that THQ is a new potent antiviral phytocompound against ZIKV, supporting the potential use of medicinal plants from Reunion Island as a source of natural and safe antiviral substances against medically important mosquito-borne viruses.

Extract prepared from the leaves of Ocimum basilicum inhibits the entry of Zika virus.

The recent Zika virus (ZIKV) outbreaks and rapid spread in tropical Latin America since introduction to Brazil in 2014, and now appearing cases in the USA, are alarming. World Health Organization (WHO) has considered transmission of ZIKV, a serious public health problem because of the increasing number of outbreaks. There are currently no drugs approved for the treatment of ZIKV infection. Discovery of safe and effective drugs are hampered by the risk in treating pregnant woman and toxicity to the fetus. Sweet basil, known as Ocimum basilicum in the scientific community, is a very well-known medicinal herb. Numerous studies have documented its beneficial activity against a great variety of human pathogens ranging from bacteria and virus to fungus and protozoans. Although, basil extracts and oils have been tested successfully against other viruses, its application to tackle ZIKV infection has not been exploited at all. In this study, we report for the first time that highly diluted ethanol extracts prepared from basil leaves can effectively inhibit ZIKV replication in Vero E6 cells with a half maximal inhibitory concentration (IC50) value of 1:134. The diluted extract as well as the amount of ethanol that goes into its preparation have been found to be completely non-toxic to the above mentioned cell line. The extract seems to inhibit the virus at the step of attachment and entry into the host cell. The specific inhibition of ZIKV observed using the basil leaf extract suggests a new alternative mode of treatment against flavivirus. Keywords: Zika virus; basil extract; antiviral.