On the sensitivity of centrality metrics.

Despite the huge importance that the centrality metrics have in understanding the topology of a network, too little is known about the effects that small alterations in the topology of the input graph induce in the norm of the vector that stores the node centralities. If so, then it could be possible to avoid re-calculating the vector of centrality metrics if some minimal changes occur in the network topology, which would allow for significant computational savings. Hence, after formalising the notion of centrality, three of the most basic metrics were herein considered (i.e., Degree, Eigenvector, and Katz centrality). To perform the simulations, two probabilistic failure models were used to describe alterations in network topology: Uniform (i.e., all nodes can be independently deleted from the network with a fixed probability) and Best Connected (i.e., the probability a node is removed depends on its degree). Our analysis suggests that, in the case of degree, small variations in the topology of the input graph determine small variations in Degree centrality, independently of the topological features of the input graph; conversely, both Eigenvector and Katz centralities can be extremely sensitive to changes in the topology of the input graph. In other words, if the input graph has some specific features, even small changes in the topology of the input graph can have catastrophic effects on the Eigenvector or Katz centrality.

The infusion of Baccharis spicata (Lam. ) Baill (Asteraceae) has antiviral activity against hepatitis B virus without cytotoxic effects against several cell lines / La infusión de Baccharis spicata (Lam. ) Baill (Asteraceae) posee actividad antiviral contra el virus de la hepatitis B sin efectos citotóxicos contra varias líneas celulares

Medicinal plants are used to cure diseases, and their replacement is frequent and affects public health. The genus Baccharis has representatives within the medicinal flora of Argentina, although the replacement of the species of this genus known under the vulgar name of "carqueja" by Baccharis spicata has been detected i n herbalists or markets of herbal products. The genotoxic safety of this species has been established in previous work of our group. The aim of this study was to evaluate the antiviral activity of an infusion made from B. spicata leaves against hepatitis B virus with the HepG2.2.15 cellular system and to determine cytotoxicity in HepG2.2,15, A549 and Vero cell lines. Infusion of B. spicata was active to inhibit HBV replication with an EC 50 of 22.54 µg/mL and a CC 50 of 190 µg/mL.

Las plantas medicinales son empleadas para la cura de enfermedades, y su sustituc ión es frecuente y afecta a la salud pública. El género Baccharis posee representantes dentro de la flora medicinal de Argentina, aunque se ha detectado la sustitución de las especies de dicho género conocidas bajo el nombre vulgar de "carqueja" por Baccha ris spicata en herboristerías o mercados de productos herb arios . Se ha establecido la seguridad genotóxica de esta especie en trabajos previos de nuestro grupo. Este estudio buscó evaluar la actividad antiviral de una infusión elaborada a partir de hojas de B. spicata frente al virus de la hepatitis B con el sistema celular HepG2.2.15 y determinar la citotoxicidad en las líneas celulares HepG2.2.15, A549 y Vero. La infusión de B. spicata fue activa para inhibir la replicación del virus con un EC 50 de 22.54 µg/mL y un CC 50 de 190 µg/mL.

Computer-aided diagnosis for breast cancer classification using deep neural networks and transfer learning.

BACKGROUND AND OBJECTIVE:  Many developed and non-developed countries worldwide suffer from cancer-related fatal diseases. In particular, the rate of breast cancer in females increases daily, partially due to unawareness and undiagnosed at the early stages. A proper first breast cancer treatment can only be provided by adequately detecting and classifying cancer during the very early stages of its development. The use of medical image analysis techniques and computer-aided diagnosis may help the acceleration and the automation of both cancer detection and classification by also training and aiding less experienced physicians. For large datasets of medical images, convolutional neural networks play a significant role in detecting and classifying cancer effectively. METHODS:  This article presents a novel computer-aided diagnosis method for breast cancer classification (both binary and multi-class), using a combination of deep neural networks (ResNet 18, ShuffleNet, and Inception-V3Net) and transfer learning on the BreakHis publicly available dataset. RESULTS AND CONCLUSIONS:  Our proposed method provides the best average accuracy for binary classification of benign or malignant cancer cases of 99.7%, 97.66%, and 96.94% for ResNet, InceptionV3Net, and ShuffleNet, respectively. Average accuracies for multi-class classification were 97.81%, 96.07%, and 95.79% for ResNet, Inception-V3Net, and ShuffleNet, respectively.

Criminal networks analysis in missing data scenarios through graph distances.

Data collected in criminal investigations may suffer from issues like: (i) incompleteness, due to the covert nature of criminal organizations; (ii) incorrectness, caused by either unintentional data collection errors or intentional deception by criminals; (iii) inconsistency, when the same information is collected into law enforcement databases multiple times, or in different formats. In this paper we analyze nine real criminal networks of different nature (i.e., Mafia networks, criminal street gangs and terrorist organizations) in order to quantify the impact of incomplete data, and to determine which network type is most affected by it. The networks are firstly pruned using two specific methods: (i) random edge removal, simulating the scenario in which the Law Enforcement Agencies fail to intercept some calls, or to spot sporadic meetings among suspects; (ii) node removal, modeling the situation in which some suspects cannot be intercepted or investigated. Finally we compute spectral distances (i.e., Adjacency, Laplacian and normalized Laplacian Spectral Distances) and matrix distances (i.e., Root Euclidean Distance) between the complete and pruned networks, which we compare using statistical analysis. Our investigation identifies two main features: first, the overall understanding of the criminal networks remains high even with incomplete data on criminal interactions (i.e., when 10% of edges are removed); second, removing even a small fraction of suspects not investigated (i.e., 2% of nodes are removed) may lead to significant misinterpretation of the overall network.

Disrupting resilient criminal networks through data analysis: The case of Sicilian Mafia.

Compared to other types of social networks, criminal networks present particularly hard challenges, due to their strong resilience to disruption, which poses severe hurdles to Law-Enforcement Agencies (LEAs). Herein, we borrow methods and tools from Social Network Analysis (SNA) to (i) unveil the structure and organization of Sicilian Mafia gangs, based on two real-world datasets, and (ii) gain insights as to how to efficiently reduce the Largest Connected Component (LCC) of two networks derived from them. Mafia networks have peculiar features in terms of the links distribution and strength, which makes them very different from other social networks, and extremely robust to exogenous perturbations. Analysts also face difficulties in collecting reliable datasets that accurately describe the gangs' internal structure and their relationships with the external world, which is why earlier studies are largely qualitative, elusive and incomplete. An added value of our work is the generation of two real-world datasets, based on raw data extracted from juridical acts, relating to a Mafia organization that operated in Sicily during the first decade of 2000s. We created two different networks, capturing phone calls and physical meetings, respectively. Our analysis simulated different intervention procedures: (i) arresting one criminal at a time (sequential node removal); and (ii) police raids (node block removal). In both the sequential, and the node block removal intervention procedures, the Betweenness centrality was the most effective strategy in prioritizing the nodes to be removed. For instance, when targeting the top 5% nodes with the largest Betweenness centrality, our simulations suggest a reduction of up to 70% in the size of the LCC. We also identified that, due the peculiar type of interactions in criminal networks (namely, the distribution of the interactions' frequency), no significant differences exist between weighted and unweighted network analysis. Our work has significant practical applications for perturbing the operations of criminal and terrorist networks.

Design and Optimization of Quinazoline Derivatives: New Non-nucleoside Inhibitors of Bovine Viral Diarrhea Virus.

Bovine viral diarrhea virus (BVDV) belongs to the Pestivirus genus (Flaviviridae). In spite of the availability of vaccines, the virus is still causing substantial financial losses to the livestock industry. In this context, the use of antiviral agents could be an alternative strategy to control and reduce viral infections. The viral RNA-dependent RNA polymerase (RdRp) is essential for the replication of the viral genome and constitutes an attractive target for the identification of antiviral compounds. In a previous work, we have identified potential molecules that dock into an allosteric binding pocket of BVDV RdRp via a structure-based virtual screening approach. One of them, N-(2-morpholinoethyl)-2-phenylquinazolin-4-amine [1, 50% effective concentration (EC50) = 9.7 ± 0.5 µM], was selected to perform different chemical modifications. Among 24 derivatives synthesized, eight of them showed considerable antiviral activity. Molecular modeling of the most active compounds showed that they bind to a pocket located in the fingers and thumb domains in BVDV RdRp, which is different from that identified for other non-nucleoside inhibitors (NNIs) such as thiosemicarbazone (TSC). We selected compound 2-[4-(2-phenylquinazolin-4-yl)piperazin-1-yl]ethanol (1.9; EC50 = 1.7 ± 0.4 µM) for further analysis. Compound 1.9 was found to inhibit the in vitro replication of TSC-resistant BVDV variants, which carry the N264D mutation in the RdRp. In addition, 1.9 presented adequate solubility in different media and a high-stability profile in murine and bovine plasma.

Validation and psychometric evaluation of the Italian version of the Spinal Cord Injury Secondary Conditions Scale.

STUDY DESIGN: Validation cross-sectional study. OBJECTIVE: To adapt the Spinal Cord Injury Secondary Conditions Scale (SCI-SCS) to Italian and to assess the validity and reliability of this instrument. SETTING: Multicentre study in outpatient clinics of three urban spinal units across Italy. METHODS: After a five-step translation/validation process, the Italian SCI-SCS was administered in a toolset composed of a sociodemographic questionnaire, the Modified Barthel Index, the Short-Form 8, the Patient Health Questionnaire 9, and the General Anxiety Disorder 7. The Italian SCI-SCS construct validity was assessed through exploratory factor analysis (EFA). The internal consistency and test-retest reliability of the instrument were evaluated using Cronbach's α and the intraclass correlation coefficient (ICC) for the total scale and its subscales. Pearson's correlation coefficient with all administered instruments was calculated to evaluate the concurrent validity. RESULTS: One-hundred fifty-six participants were recruited from February to October 2018. EFA suggested a three-factor structure explaining 45% of the total variance. After experts' consideration about the clinical relevance of its components, a final version of the Italian SCI-SCS with four different subscales and 15 items was proposed. The total scale Cronbach's α was 0.73. The ICC agreement for test-retest reliability was 0.91. Correlations of the Italian SCI-SCS with the administered instruments were statistically significant (p < 0.05), highlighting congruent hypothesized relations. CONCLUSION: Findings of this study provided a first psychometric evaluation of the SCI-SCS. The modified Italian version of this tool may represent a valuable instrument for the longitudinal assessment of the impact of secondary conditions in people with SCI.

Antiviral activity of flavonoids present in aerial parts of Marcetia taxifolia against Hepatitis B virus, Poliovirus, and Herpes Simplex Virus in vitro.

Marcetia taxifolia is a neotropical plant present in South America and it has been evaluated in several biological models due to the presence of active metabolites. Nevertheless, there is a limited quantity of studies related to the antiviral activity of the compounds present in this genus. In our work, the antiviral effect of the compounds isolated from the aerial parts of Marcetia taxifolia was evaluated against Hepatitis B virus (HBV), Herpes Simplex Virus type 1 (HSV-1), and Poliovirus type 1 (PV-1). The cytopathic effect and viral quantification by qPCR were determined as indicative of antiviral activity. Our data show that myricetin rhamnoside (MyrG), myricetin-3-α-O-ramnosil (1→6)-α-galactoside (MyrGG), 5,3'-dihydroxy-3,6,7,8,4'-pentamethoxyflavone (PMF), 5-hydroxy-3,6,7,3',4'pentamethoxyflavone (PMF-OH) had antiviral activity without cytotoxic effects. The methoxyflavones PMF and PMF-OH were the most active compounds, showing an antiviral effect against all the evaluated viruses. Computational studies showed that these compounds could interact with the Reverse Transcriptase. Altogether, these results suggest that the flavonoids (related to myricetin and methoxyflavones) are the main antiviral compounds present in the aerial parts of Marcetia taxifolia. Furthermore, our results showed that the methoxyflavones have a broad antiviral activity, which represents an opportunity to evaluate these flavonoids as lead molecules to develop new antiviral compounds.

Adaptation and validation of the Caregiver Burden Inventory in Spinal Cord Injuries (CBI-SCI).

DESIGN: Validation cross-sectional study. OBJECTIVES: Even though caregiver burden (CB) represents a well-recognised concern among caregivers of people with a spinal cord injury (SCI), there are no specific questionnaires designed for its evaluation. This study aimed to assess the psychometric properties of the Caregiver Burden Inventory in Spinal Cord Injury (CBI-SCI), which was modified from its original version, and specifically its construct and reliability. SETTING: Multicentre study in four urban spinal units across Italy. The CBI-SCI was administered to family caregivers in outpatient clinics. METHODS: CBI-SCI was administered in a toolset composed of a sociodemographic questionnaire, the Family Strain Questionnaire-Short Form (FSQ-SF), the Short Form-36 (SF-36), and the Modified Barthel Index (MBI). The CBI-SCI construct validity was assessed through an exploratory factor analysis. The internal consistency of the questionnaire was examined using Cronbach's alpha (α) coefficient for the total scale and its subscales. Concurrent validity was evaluated performing Pearson's correlation coefficient with all instruments included in the toolset. RESULTS: The CBI-SCI was administered to 176 participants from February 2016 to September 2017. Factor analysis highlighted the five-factored structure of the questionnaire. The total scale Cronbach's α was 0.91 (p < 0.001). All the five subscales of CBI-SCI showed an acceptable internal consistency, ranging from 0.76 to 0.91 (p < 0.001). Pearson's correlation coefficients of the CBI-SCI with all the administered instruments were statistically significant (p < 0.001), showing congruent relations. CONCLUSION: The CBI-SCI, due to its validity and reliability, may represent a valuable instrument to evaluate the CB longitudinally in SCI.

Identification of potent bovine viral diarrhea virus inhibitors by a structure-based virtual screening approach.

Bovine viral diarrhea virus (BVDV) is a pestivirus whose infection in cattle is globally distributed. The use of antivirals could complement vaccination as a tool of control and reduce economic losses. The RNA-dependent RNA polymerase (RdRp) of the virus is essential for its genome replication and constitutes an attractive target for the identification of antivirals. With the aim of obtaining selective BVDV inhibitors, the crystal structure of BVDV RdRp was used to perform a virtual screening. Approximately 15,000 small molecules from commercial and in-house databases were evaluated and several structurally different compounds were tested in vitro for antiviral activity. Interestingly, of twelve evaluated compounds, five were active and displayed EC50 values in the sub and low-micromolar range. Time of drug addition experiment and measured intracellular BVDV RNA showed that compound 7 act during RNA synthesis. Molecular Dynamics and MM/PBSA calculation were done to characterize the interaction of the most active compounds with RdRp, which will allow future ligand optimization. These studies highlight the use of in silico screening to identify a new class of BVDV inhibitors.

Synthesis, antiviral evaluation and molecular docking studies of N4-aryl substituted/unsubstituted thiosemicarbazones derived from 1-indanones as potent anti-bovine viral diarrhea virus agents.

A series of N4-arylsubstituted thiosemicarbazones derived from 1-indanones and a set of compounds lacking such substitution in the N4 position of the thiosemicarbazone moiety were synthesized and evaluated for their anti-bovine viral diarrhea virus (BVDV) activity. Among these, derivatives 2 and 15 displayed high activity (EC50=2.7±0.4 and 0.7±0.1µM, respectively) as inhibitors of BVDV replication. Novel key structural features related to the anti-BVDV activity were identified by structure-activity relationship (SAR) analysis. In a previous study, the thiosemicarbazone of 5,6-dimethoxy-1-indanone (5,6-TSC) was characterized as a non-nucleoside inhibitor (NNI) of the BVDV RNA-dependent RNA polymerase. In the present work, cross-resistance assays were performed with the most active compounds. Such studies were carried out on 5,6-TSC resistant BVDV (BVDV-TSCr T1) carrying mutations in the viral polymerase. This BVDV mutant was also resistant to compound 15. Molecular docking studies and MM/PBSA calculations were performed to assess the most active derivatives at the 5,6-TSC viral polymerase binding site. The differences in the interaction pattern and the binding affinity of derivative 15 either to the wild type or BVDV-TSCr T1 polymerase were key factors to define the mode of action of this compound.

Complexation of a 1-Indanone Thiosemicarbazone with Hydroxypropyl-ß-Cyclodextrin Enhances Its Activity Against a Hepatitis C Virus Surrogate Model.

The current standard of care of the infection by hepatitis C virus (HCV) is effective in a limited number of patients and the high cost hinders therapy affordability and compliance. In this context, the research of new direct-acting antiviral agents (DAAs) for a more effective and long-lasting therapy is an urgent need and an area of active investigation. In an effort to develop novel DAAs, a series of 1-indanone thiosemicarbazones (TSCs) was synthesized and fully characterized. However, the high self-aggregation tendency and extremely poor aqueous solubility of these antiviral candidates often preclude their reliable biological evaluation in vitro. To maintain constant TSC concentrations over the biological assays, different TSC/cyclodextrin complexes were produced. In the present work, we report for the first time the cytotoxicity and antiviral activity of 5,6-dimethoxy TSC inclusion complexes with hydroxypropyl-ß-cyclodextrin on bovine viral diarrhea virus (BVDV) as HCV surrogate model. Results showed a potent suppression of the virus replication, with greater activity for the inclusion complexes than the free compound.

Stability of the resistance to the thiosemicarbazone derived from 5,6-dimethoxy-1-indanone, a non-nucleoside polymerase inhibitor of bovine viral diarrhea virus.

Bovine viral diarrhea virus (BVDV) is the prototype Pestivirus. BVDV infection is distributed worldwide and causes serious problems for the livestock industry. The thiosemicarbazone of 5,6-dimethoxy-1-indanone (TSC) is a non-nucleoside polymerase inhibitor (NNI) of BVDV. All TSC-resistant BVDV variants (BVDV-TSCr T1-5) present an N264D mutation in the NS5B gene (RdRp) whereas the variant BVDV-TSCr T1 also presents an NS5B A392E mutation. In the present study, we carried out twenty passages of BVDV-TSCr T1-5 in MDBK cells in the absence of TSC to evaluate the stability of the resistance. The viral populations obtained (BVDV R1-5) remained resistant to the antiviral compound and conserved the mutations in NS5B associated with this phenotype. Along the passages, BVDV R2, R3 and R5 presented a delay in the production of cytopathic effect that correlated with a decrease in cell apoptosis and intracellular accumulation of viral RNA. The complete genome sequences that encode for NS2 to NS5B, Npro and Erns were analyzed. Additional mutations were detected in the NS5B of BVDV R1, R3 and R4. In both BVDV R2 and R3, most of the mutations found were localized in NS5A, whereas in BVDV R5, the only mutation fixed was NS5A V177A. These results suggest that mutations in NS5A could alter BVDV cytopathogenicity. In conclusion, the stability of the resistance to TSC may be due to the fixation of different compensatory mutations in each BVDV-TSCr. During their replication in a TSC-free medium, some virus populations presented a kind of interaction with the host cell that resembled a persistent infection: decreased cytopathogenicity and viral genome synthesis. This is the first report on the stability of antiviral resistance and on the evolution of NNI-resistant BVDV variants. The results obtained for BVDV-TSCr could also be applied for other NNIs.

Antipoliovirus Activity of the Organic Extract of Eupatorium buniifolium: Isolation of Euparin as an Active Compound.

The antiviral activity of the organic extract (OE) of Eupatorium buniifolium against poliovirus type 1 was determined by in vitro assays with an effective concentration 50 (EC50) of 23.3 ± 3.3 µg/mL. Bioassay-guided fractionation of the OE allowed the isolation of an active principle that was identified by spectroscopic methods ((1)H- and (13)C-NMR, EI-MS, UV, and IR spectroscopy) as the benzofuran euparin. The plaque reduction assay in Vero cells was used to assess the antiviral activity of euparin against poliovirus types 1, 2, and 3 with EC50 values of 0.47, 0.12, and 0.15 µg/mL, respectively. Moreover, this compound showed high selectivity indexes of 284.9, 1068, and 854.7, respectively. In order to identify the mechanism by which euparin exerts its antiviral activity, the virucidal effect, the pretreatment of Vero cells, and the time of action on one viral replication cycle were evaluated. Results obtained demonstrated that euparin exerts its effect during the early events of the replication cycle, from the virus adsorption to cells up to the first twenty minutes after infection. This is the first report on the presence of euparin in E. buniifolium and its antiviral activity.

In vitro antiviral activity of plant extracts from Asteraceae medicinal plants.

BACKGROUND: Due to the high prevalence of viral infections having no specific treatment and the constant appearance of resistant viral strains, the development of novel antiviral agents is essential. The aim of this study was to evaluate the antiviral activity against bovine viral diarrhea virus, herpes simplex virus type 1 (HSV-1), poliovirus type 2 (PV-2) and vesicular stomatitis virus of organic (OE) and aqueous extracts (AE) from: Baccharis gaudichaudiana, B. spicata, Bidens subalternans, Pluchea sagittalis, Tagetes minuta and Tessaria absinthioides. A characterization of the antiviral activity of B. gaudichaudiana OE and AE and the bioassay-guided fractionation of the former and isolation of one active compound is also reported. METHODS: The antiviral activity of the OE and AE of the selected plants was evaluated by reduction of the viral cytopathic effect. Active extracts were then assessed by plaque reduction assays. The antiviral activity of the most active extracts was characterized by evaluating their effect on the pretreatment, the virucidal activity and the effect on the adsorption or post-adsorption period of the viral cycle. The bioassay-guided fractionation of B. gaudichaudiana OE was carried out by column chromatography followed by semipreparative high performance liquid chromatography fractionation of the most active fraction and isolation of an active compound. The antiviral activity of this compound was also evaluated by plaque assay. RESULTS: B. gaudichaudiana and B. spicata OE were active against PV-2 and VSV. T. absinthioides OE was only active against PV-2. The corresponding three AE were active against HSV-1. B. gaudichaudiana extracts (OE and AE) were the most selective ones with selectivity index (SI) values of 10.9 (PV-2) and > 117 (HSV-1). For this reason, both extracts of B. gaudichaudiana were selected to characterize their antiviral effects. Further bioassay-guided fractionation of B. gaudichaudiana OE led to an active fraction, FC (EC50 = 3.1 µg/ml; SI = 37.9), which showed antiviral activity during the first 4 h of the viral replication cycle of PV-2 and from which the flavonoid apigenin (EC50 = 12.2 ± 3.3 µM) was isolated as a major compound. CONCLUSIONS: The results showed that, among the species studied, B. gaudichaudiana seemed to be the most promising species as a source of antiviral agents.

Synthesis and biological evaluation of novel homochiral carbocyclic nucleosides from 1-amino-2-indanols.

New chiral purinyl and 8-azapurinyl carbanucleoside derivatives based on indanol were synthesized from commercial available (1S,2S)-trans-1-amino-2-indanol and (1R,2R)-trans-1-amino-2-indanol using a linear methodology. The antiviral activity and cytotoxicity of these compounds were evaluated against herpes simplex virus type 1 (HSV-1) in Vero cells, bovine viral diarrhea virus (BVDV) in Mardin-Darby bovine kidney (MDBK) cells and hepatitis B virus (HBV) in HepG2 2.2.15 cell line. Three compounds, showed an inhibition of the HBsAg levels similar to reference drug lamivudine. One chloropurinyl nucleoside, derived from the cis-1-amino-2-indanol, was cytotoxic on MDBK cells and it could be a lead for developing anticancer agents.

In vitro evaluation of antiprotozoal and antiviral activities of extracts from Argentinean Mikania species.

The aim of this study was to investigate the antiprotozoal and antiviral activities of four Argentinean Mikania species. The organic and aqueous extracts of Mikania micrantha, M. parodii, M. periplocifolia, and M. cordifolia were tested on Trypanosoma cruzi epimastigotes, Leishmania braziliensis promastigotes, and dengue virus type 2. The organic extract of M. micrantha was the most active against T. cruzi and L. braziliensis exhibiting a growth inhibition of 77.6 ± 4.5% and 84.9 ± 6.1%, respectively, at a concentration of 10 µg/ml. The bioguided fractionation of M. micrantha organic extract led to the identification of two active fractions. The chromatographic profile and infrared analysis of these fractions revealed the presence of sesquiterpene lactones. None of the tested extracts were active against dengue virus type 2.

Cytotoxic, virucidal, and antiviral activity of South American plant and algae extracts.

Herpes simplex virus type 1 (HSV-1) infection has a prevalence of 70% in the human population. Treatment is based on acyclovir, valacyclovir, and foscarnet, three drugs that share the same mechanism of action and of which resistant strains have been isolated from patients. In this aspect, innovative drug therapies are required. Natural products offer unlimited opportunities for the discovery of antiviral compounds. In this study, 28 extracts corresponding to 24 plant species and 4 alga species were assayed in vitro to detect antiviral activity against HSV-1. Six of the methanolic extracts inactivated viral particles by direct interaction and 14 presented antiviral activity when incubated with cells already infected. Most interesting antiviral activity values obtained are those of Limonium brasiliense, Psidium guajava, and Phyllanthus niruri, which inhibit HSV-1 replication in vitro with 50% effective concentration (EC(50)) values of 185, 118, and 60 µg/mL, respectively. For these extracts toxicity values were calculated and therefore selectivity indexes (SI) obtained. Further characterization of the bioactive components of antiviral plants will pave the way for the discovery of new compounds against HSV-1.

Inhibition of bovine viral diarrhea virus RNA synthesis by thiosemicarbazone derived from 5,6-dimethoxy-1-indanone.

In the present work, we described the activity of the thiosemicarbazone derived from 5,6-dimethoxy-1-indanone (TSC), which we previously characterized as a new compound that inhibits bovine viral diarrhea virus (BVDV) infection. We showed that TSC acts at a point of time that coincides with the onset of viral RNA synthesis and that it inhibits the activity of BVDV replication complexes (RCs). Moreover, we have selected five BVDV mutants that turned out to be highly resistant to TSC but still susceptible to ribavirin (RBV). Four of these resistant mutants carried an N264D mutation in the viral RNA-dependent RNA polymerase (RdRp). The remaining mutant showed an A392E mutation within the same protein. Some of these mutants replicated slower than the wild-type (wt) virus in the absence of TSC, whereas others showed a partial reversion to the wt phenotype over several passages in the absence of the compound. The docking of TSC in the crystal structure of the BVDV RdRp revealed a close contact between the indane ring of the compound and several residues within the fingers domain of the enzyme, some hydrophobic contacts, and hydrogen bonds with the thiosemicarbazone group. Finally, in the mutated RdRp from resistant BVDV, these interactions with TSC could not be achieved. Interestingly, TSC inhibited BVDV replication in cell culture synergistically with RBV. In conclusion, TSC emerges as a new nonnucleoside inhibitor of BVDV RdRp that is synergistic with RBV, a feature that turns it into a potential compound to be evaluated against hepatitis C virus (HCV).

Antiviral activity of 5'-O-carbonate-2',3'-dideoxy-3'-thiacytidine prodrugs against hepatitis B virus in HepG2 2.2.15 cells.

The antiviral activities of lamivudine (3TC; 2',3'-dideoxy-3'-thiacytidine) and six 5'-O-carbonates of 3TC were determined by inhibition of hepatitis B virus (HBV) replication in HepG2 2.2.15 cells. HBV DNA in cell supernatants was quantified by real-time polymerase chain reaction (PCR). The results showed that 3TC-Etha was six times more active than 3TC and that 3TC-Buta, 3TC-Hexa and 3TC-Octa were approximately three times more active than 3TC. In contrast, 3TC-Penta and 3TC-Metha showed anti-HBV activity similar to that of the parent compound 3TC. In conclusion, 5'-O-carbonates of 3TC appear to be promising candidates as anti-HBV compounds. This modification could optimise the use of 3TC, a well-tolerated, effective and inexpensive drug, in monotherapy or combined therapy for chronic HBV infections as well as human immunodeficiency virus (HIV)/HBV co-infections.