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Ribavirin (RBV), which is extensively used to treat viral diseases such as COVID-19, is considered one of the major emerging contaminants due to its long-term existence and health risk in the aqueous environmental system. However, research on effective removal of RBV still remains insufficient. In this study, we investigated the RBV degradation kinetics and mechanism in UV/chlorine/Fe(II) process. The degradation rate constant k obs-RBV of RBV was 2.52 × 10 -4 s -1 in UV/chlorine/Fe(II) process, which increased by 1.6 times and 1.3 times than that in chlorine alone and UV/chlorine process, respectively. Notably, trace amount Fe(II) promoted RBV degradation in UV/chlorine system through Fe 2+ /Fe 3+ cycles, enhancing the yield of reactive species such as HO· and certain species reactive chlorine radicals (RCS). The contributions of HO· and RCS toward RBV degradation were 53.91% and 16.11%, respectively. Specifically, Cl·, ClO·, and Cl 2 · - were responsible for 8.59%, 2.69%, and 4.83% of RBV removal. The RBV degradation pathway indicated that the reactive species preferentially attacked the amide moiety of RBV, which cleaved the ether bond and the hydroxyl group. The toxicity evaluation of RBV degradation products elucidated that UV/chlorine/Fe(II) process was beneficial for RBV detoxification., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

α-Synuclein (α-syn) is an intrinsically disordered protein, linked genetically and neuropathologically to Parkinson's disease where this protein aggregates within the brain. Hence, identifying compounds capable of impeding α-syn aggregation puts forward a promising approach for the development of disease-modifying therapies. Herein, we investigated the efficacy of Ribavirin, an FDA-approved compound, in curtailing α-syn amyloid transformation, employing an array of bioinformatic tools and systematic analysis using biophysical techniques. Ribavirin shows a dose dependent anti-aggregation propensity where it effectively subdued the formation of mature fibrillar aggregates of α-syn, where even at the lowest concentration there was a 69 % reduction in the ThT maxima. Ribavirin averts the formation of mature fibrillar aggregates by interacting with the NAC domain of α-syn. Ribavirin redirects the amyloid transformation of α-syn by emanating aggregates of lower order with reduced cross β-sheet signature and revokes the formation of on-pathway amyloids. Collectively, our study puts forward the novel potency of Ribavirin as a promising molecule for therapeutic intervention in Parkinson's disease., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial or personal interests that could appear to have influenced the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Drug delivery to central nervous pathologies is compromised by the blood-brain barrier (BBB). A clinically explored strategy to promote drug delivery across the BBB is sonopermeation, which relies on the combined use of ultrasound (US) and microbubbles (MB) to induce temporally and spatially controlled opening of the BBB. We developed an advanced in vitro BBB model to study the impact of sonopermeation on the delivery of the prototypic polymeric drug carrier pHPMA as a larger molecule and the small molecule antiviral drug ribavirin. This was done under standard and under inflammatory conditions, employing both untargeted and RGD peptide-coated MB. The BBB model is based on human cerebral capillary endothelial cells and human placental pericytes, which are co-cultivated in transwell inserts and which present with proper transendothelial electrical resistance (TEER). Sonopermeation induced a significant decrease in TEER values and facilitated the trans-BBB delivery of fluorescently labeled pHPMA (Atto488-pHPMA). To study drug delivery under inflamed endothelial conditions, which are typical for e.g. tumors, neurodegenerative diseases and CNS infections, tumor necrosis factor (TNF) was employed to induce inflammation in the BBB model. RGD-coated MB bound to and permeabilized the inflamed endothelium-pericyte co-culture model, and potently improved Atto488-pHPMA and ribavirin delivery. Taken together, our work combines in vitro BBB bioengineering with MB-mediated drug delivery enhancement, thereby providing a framework for future studies on optimization of US-mediated drug delivery to the brain., (© 2024. The Author(s).)

Increasing drug residues in aquatic environments have been caused by the abuse of antivirals since the global spread of the COVID-19 epidemic, whereas research on the photolytic mechanism, pathways and toxicity of these drugs is limited. The concentration of COVID-19 antivirals ribavirin in rivers has been reported to increase after the epidemic. Its photolytic behavior and environmental risk in actual waters such as wastewater treatment plant (WWTP) effluent, river water and lake water were first investigated in this study. Direct photolysis of ribavirin in these media was limited, but indirect photolysis was promoted in WWTP effluent and lake water by dissolved organic matter and NO 3 - . Identification of photolytic intermediates suggested that ribavirin was photolyzed mainly via C-N bond cleavage, splitting of the furan ring and oxidation of the hydroxyl group. Notably, the acute toxicity was increased after ribavirin photolysis owing to the higher toxicity of most of the products. Additionally, the overall toxicity was greater when ARB photolysis in WWTP effluent and lake water. These findings emphasize the necessity to concern about the toxicity of ribavirin transformation in natural waters, as well as to limit its usage and discharge., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The outbreak of a novel febrile respiratory disease called COVID-19, caused by a newfound coronavirus SARS-CoV-2, has brought a worldwide attention. Prioritizing approved drugs is critical for quick clinical trials against COVID-19. In this study, we first manually curated three Virus-Drug Association (VDA) datasets. By incorporating VDAs with the similarity between drugs and that between viruses, we constructed a heterogeneous Virus-Drug network. A novel Random Walk with Restart method (VDA-RWR) was then developed to identify possible VDAs related to SARS-CoV-2. We compared VDA-RWR with three state-of-the-art association prediction models based on fivefold cross-validations (CVs) on viruses, drugs and virus-drug associations on three datasets. VDA-RWR obtained the best AUCs for the three fivefold CVs, significantly outperforming other methods. We found two small molecules coming together on the three datasets, that is, remdesivir and ribavirin. These two chemical agents have higher molecular binding energies of - 7.0 kcal/mol and - 6.59 kcal/mol with the domain bound structure of the human receptor angiotensin converting enzyme 2 (ACE2) and the SARS-CoV-2 spike protein, respectively. Interestingly, for the first time, experimental results suggested that navitoclax could be potentially applied to stop SARS-CoV-2 and remains to further validation.

We started a study on the molecular docking of six potential pharmacologically active inhibitors compounds that can be used clinically against the COVID-19 virus, in this case, remdesivir, ribavirin, favipiravir, galidesivir, hydroxychloroquine and chloroquine interacting with the main COVID-19 protease in complex with a COVID-19 N3 protease inhibitor. The highest values of affinity energy found in order from highest to lowest were chloroquine (CHL), hydroxychloroquine (HYC), favipiravir (FAV), galidesivir (GAL), remdesivir (REM) and ribavirin (RIB). The possible formation of hydrogen bonds, associations through London forces and permanent electric dipole were analyzed. The values of affinity energy obtained for the hydroxychloroquine ligands was -9.9 kcal/mol and for the chloroquine of -10.8 kcal/mol which indicate that the coupling contributes to an effective improvement of the affinity energies with the protease. Indicating that, the position chosen to make the substitutions may be a pharmacophoric group, and cause changes in the protease.

The synthesis and characterization of a lead-free perovskite-type material, (C 13 H 14 N 6 F 2 O) 2 Bi 2 I 10 is reported. It exhibits a zero-dimensional (0D) Bi 2 I 10 4- octahedral unit, surrounded by a flexible tripodal antifungal ligand (H 2 Fluconazole) 2+ . The several intermolecular interactions of the independent cation and the bismuth iodide octahedra were tested via the Hirshfeld surface analysis. The detailed interpretation of the vibrational modes was carried out. The band gap (Eg) of 2.10 eV agrees with the theoretical values. Upon photoexcitation, the crystals exhibit a broadband green emission peaked at 534 nm, which originates from electronic transitions within the inorganic cluster [Bi 2 I 10 ] 4- . The theoretical calculations were carried out using DFT and TD-DFT methods to appraise the molecular geometry, vibrational spectra, electronic absorption spectra, frontier molecular orbitals (FOMs) and global reactivity descriptors. Calculations reveal that the energy gap (Eg) and other chemical reactivity descriptors are primarily linked to the inorganic anion and the triazolium rings (A and B) of the organic cation reflecting their importance in the activity and the antioxidant ability of the molecule., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The novel coronavirus, COVID-19, caused by SARS-CoV-2, is a global health pandemic that started in December 2019. The effective drug target among coronaviruses is the main protease M pro , because of its essential role in processing the polyproteins that are translated from the viral RNA. In this study, the bioactivity of some selected heterocyclic drugs named Favipiravir ( 1 ), Amodiaquine ( 2 ), 2'-Fluoro-2'-deoxycytidine ( 3 ), and Ribavirin ( 4 ) was evaluated as inhibitors and nucleotide analogues for COVID-19 using computational modeling strategies. The density functional theory (DFT) calculations were performed to estimate the thermal parameters, dipole moment, polarizability, and molecular electrostatic potential of the present drugs; additionally, Mulliken atomic charges of the drugs as well as the chemical reactivity descriptors were investigated. The nominated drugs were docked on SARS-CoV-2 main protease (PDB: 6LU7) to evaluate the binding affinity of these drugs. Besides, the computations data of DFT the docking simulation studies was predicted that the Amodiaquine ( 2 ) has the least binding energy (-7.77 Kcal/mol) and might serve as a good inhibitor to SARS-CoV-2 comparable with the approved medicines, hydroxychloroquine, and remdesivir which have binding affinity -6.06 and -4.96 Kcal/mol, respectively. The high binding affinity of 2 was attributed to the presence of three hydrogen bonds along with different hydrophobic interactions between the drug and the critical amino acids residues of the receptor. Finally, the estimated molecular electrostatic potential results by DFT were used to illustrate the molecular docking findings. The DFT calculations showed that drug 2 has the highest of lying HOMO, electrophilicity index, basicity, and dipole moment. All these parameters could share with different extent to significantly affect the binding affinity of these drugs with the active protein sites.

Aims: A newly emerged Human Coronavirus (HCoV) is reported two months ago in Wuhan, China (COVID-19). Until today >2700 deaths from the 80,000 confirmed cases reported mainly in China and 40 other countries. Human to human transmission is confirmed for COVID-19 by China a month ago. Based on the World Health Organization (WHO) reports, SARS HCoV is responsible for >8000 cases with confirmed 774 deaths. Additionally, MERS HCoV is responsible for 858 deaths out of about 2500 reported cases. The current study aims to test anti-HCV drugs against COVID-19 RNA dependent RNA polymerase (RdRp)., Materials and Methods: In this study, sequence analysis, modeling, and docking are used to build a model for Wuhan COVID-19 RdRp. Additionally, the newly emerged Wuhan HCoV RdRp model is targeted by anti-polymerase drugs, including the approved drugs Sofosbuvir and Ribavirin., Key Findings: The results suggest the effectiveness of Sofosbuvir, IDX-184, Ribavirin, and Remidisvir as potent drugs against the newly emerged HCoV disease., Significance: The present study presents a perfect model for COVID-19 RdRp enabling its testing in silico against anti-polymerase drugs. Besides, the study presents some drugs that previously proved its efficiency against the newly emerged viral infection., Competing Interests: Declaration of competing interest The author declares that there is no competing interest in this work., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The computational search of chemical libraries has been used as a powerful tool for the rapid discovery of candidate compounds. To find small molecules with anti-feline infectious peritonitis virus (FIPV) properties, we utilized a virtual screening technique to identify the active site on the viral protease for the binding of the available natural compounds. The protease 3CL (3CL pro ) plays an important role in the replication cycle of FIPV and other viruses within the family Coronaviridae. The 15 best-ranked candidate consensus compounds, based on three docking tools, were evaluated for further assays. The protease inhibitor assay on recombinant FIPV 3CL pro was performed to screen the inhibitory effect of the candidate compounds with IC 50 ranging from 6.36 ± 2.15 to 78.40 ± 2.60 μM. As determined by the cell-based assay, the compounds NSC345647, NSC87511, and NSC343256 showed better EC 50 values than the broad-spectrum antiviral drug ribavirin and the protease inhibitor lopinavir, under all the test conditions including pre-viral entry, post-viral entry, and prophylactic activity. The NSC87511 particularly yielded the best selective index (>4; range of SI = 13.80-22.90). These results indicated that the natural small-molecular compounds specifically targeted the 3CL pro of FIPV and inhibited its replication. Structural modification of these compounds may generate a higher anti-viral potency for the further development of a novel therapy against FIP., Competing Interests: Declaration of competing interest None., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Current estimates indicate that hepatocarcinoma is the leading cause of death globally. There is interest in utilizing nanomedicine for cancer therapy to overcome side effects of chemo-interventions. Ribavirin, an antiviral nucleoside inhibitor, accumulates inside red blood cells, causing anemia. Its analog, viramidine, can concentrate within hepatocytes and spare red blood cells, thus limiting anemia. Hepatocarcinoma cells have a large number of asialoglycoprotein receptors on their membranes that can bind galactosyl-terminating solid lipid nanoparticles (Gal-SLN) and internalize them. Here, viramidine, 5-fluorouracil, and paclitaxel-loaded Gal-SLN were characterized inside cells. Cytotoxicities of free-drug, nano-void, and drug-loaded Gal-SLN were evaluated using HepG2 cells; over 3 days, cell viability was measured. To test the mechanistic pathway, we investigated in vitro apoptosis using flow cytometry and in ovo angiogenesis using the CAM assay. Results showed that 1 and 2 μM of the viramidine-encapsulated Gal-SLN had the highest cytotoxic effect, achieving 80% cell death with a steady increase over 3 days, with induction of apoptosis and reduction of necrosis and angiogenesis, compared to free-drugs. Gal-SLN application on breast cancer MCF-7 cells confirmed its specificity against liver cancer HepG2 cells. We conclude that viramidine-encapsulated Gal-SLN has anticancer and anti-angiogenic activities against hepatocarcinoma.

Three novel tiazofurin analogues having d-arabino stereochemistry and nitrogen functionalities at the C-2' position (5-7) have been designed and synthesized in multistep sequences, starting from d-glucose. The known d-xylo stereoisomer of 1 (compound 2) along with two new analogues bearing nitrogen functions at the C-3' (3 and 4) has also been synthesized from the same sugar precursor. The synthetic sequence consisted of the following three stages: (i) the multistep synthesis of suitably protected pentofuranosyl cyanides, (ii) the construction of ethyl thiazole-4-carboxylate part by cyclocondensation of thus obtained glycofuranosyl cyanides with l-cysteine ethyl ester followed by dehydrogenation, and (iii) the final transformation of the ethyl thiazole-4-carboxylates into the target tiazofurin analogues using the esters ammonolysis. The tiazofurin analogues were evaluated for their antitumour activities in cell-culture-based assays. Compounds 3, 4 (d-xylo) and 7 (d-arabino), showed remarkable antitumour activities, with IC 50 values in the range of 4-7 nM. Preliminary structure-activity relationship allowed identification of two analogues with antiproliferative activities exceeding that of the parent compound 1 for several orders of magnitude (e.g. 4: 1354-fold against Raji, 7: 309-fold against K562). Flow cytometry data and Western blot analysis suggested that cytotoxic effects of d-xylo stereoisomers in the culture of K562 cells caused changes in the cell cycle distribution, as well as the induction of apoptosis in caspase-dependent way. The increase of apoptotic cells percentage in treated samples is also confirmed with fluorescent double-staining method. Genotoxicity testing showed that the analogues with the xylo-configuration (2-4) are far less genotoxic than tiazofurin., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Common antivirals include nucleoside or nucleotide analogs with base prodrugs. The antiviral ribavirin, a US Food and Drug Administration (FDA)-approved nucleoside antimetabolite, halts guanine production, mutagenizes viral genomes, and activates interferon signaling. Here, we find that ribavirin induces spermidine-spermine N1-acetyltransferase (SAT1), a polyamine catabolic enzyme. Polyamines are small, positively charged molecules involved in cellular functions such as transcription and translation. Previous work showed that SAT1 activation and polyamine depletion interfere with RNA virus replication. We show ribavirin depletes polyamines via SAT1, in conjunction with its known mechanisms. SAT1 transcripts, protein, and activity are induced in a dose-dependent manner, which depletes polyamine levels and reduces viral titers. Inhibition of SAT1 activity, pharmacologically or genetically, reduces ribavirin's effectiveness against three virus infection models. Additionally, ribavirin-mediated polyamine depletion results from nucleotide pool depletion. These data demonstrate another mechanism of ribavirin that inform its clinical effectiveness, which may provide insight for improved therapies., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

This study describes a simple, sensitive, specific and generic HPLC-DAD method for simultaneous determination of four drugs prescribed for treatment of Hepatitis C Virus (HCV) infection. Investigated drugs include daclatasvir (DAC), ledipasvir (LED), sofosbuvir (SOF) and ribavirin (RIB). Successful separation was accomplished using Thermohypersil BDS-C8 column (4.6 × 250 mm, 5 µm) with gradient elution of the mobile phase consisted of mixed phosphate buffer pH 7.5 and methanol. Gradient elution started with 25% methanol, ramped up linearly to 80% in 15 min then kept constant till the end of the run. Flow rate was 1.5 mL/min. Peak areas were measured at 235, 260, 315, and 332 nm for RIB, SOF, DAC, and LED, respectively. Peaks of the analytes were perfectly resolved with retention times 2.0, 12.1, 14.7, and 17.2 min for RIB, SOF, DAC, and LED, respectively. The developed method was validated according to ICH guidelines with respect to system suitability, linearity, ranges, accuracy, precision, specificity, robustness, and limits of detection and quantification. The proposed method showed good linearity in the ranges 5-500, 2-300, 0.5-75, and 0.5-75 µg/mL for RIB, SOF, DAC, and LED respectively. Limits of detection were 0.10-0.66 μg/mL for the analyzed drugs. Specificity was established by separation of target drugs from 7 process-related impurities for SOF including its major metabolite (GS-331007). Applicability of the proposed method to real life situations was assessed through the analysis of four different pharmaceutical formulations and satisfactory results were obtained. Additionally, dissolution profiles of the 4 drugs were studied using the developed method.

A series of myricetin derivatives containing amide, thioether, and 1,3,4-thiadiazole moieties were designed and synthesized, and their antiviral and antibacterial activities were assessed. The bioassays showed that all the title compounds exhibited potent in vitro antibacterial activities against Xanthomonas citri ( Xac ), Ralstonia solanacearum ( Rs ), and Xanthomonas oryzae pv. Oryzae ( Xoo ). In particular, the compounds 5a , 5f , 5g , 5h , 5i, and 5l , with EC 50 values of 11.5⁻27.3 μg/mL, showed potent antibacterial activity against Xac that was better than the commercial bactericides Bismerthiazol (34.7 μg/mL) and Thiodiazole copper (41.1% μg/mL). Moreover, the in vivo antiviral activities against tobacco mosaic virus (TMV) of the target compounds were also tested. Among these compounds, the curative, protection, and inactivation activities of 5g were 49.9, 52.9, and 73.3%, respectively, which were better than that of the commercial antiviral Ribavirin (40.6, 51.1, and 71.1%, respectively). This study demonstrates that myricetin derivatives bearing amide, thioether, and 1,3,4-thiadiazole moieties can serve as potential alternative templates for the development of novel, highly efficient inhibitors against plant pathogenic bacteria and viruses.

Trichomonas vaginalis infects approximately 300 million people worldwide annually. Infected individuals have a higher susceptibility to more serious conditions such as cervical and prostate cancer. The parasite has developed increasing resistance to current drug therapies, with an estimated 5% of clinical cases resulting from resistant strains, creating the need for new therapeutic strategies with novel mechanisms of action. Nucleoside salvage pathway enzymes represent novel drug targets as these pathways are essential for the parasite's survival. The guanosine/adenosine/cytidine nucleoside hydrolase (GACNH) may be particularly important as its expression is upregulated under glucose-limiting conditions mimicking those that occur during infection establishment. GACNH was screened against the NIH Clinical Collection to explore its druggability. Seven compounds were identified with IC 50 values <20 μM. Extensive overlap was found between inhibitors of GACNH and the adenosine/guanosine nucleoside hydrolase (AGNH), but no overlap was found with inhibitors of the uridine nucleoside hydrolase. The guanosine analog ribavirin was the only compound found to be specific for GACNH. Compounds that inhibit both AGNH and GACNH purine salvage pathway enzymes may prove critical given the role that GACNH appears to play in the early stages of infection., (© 2018 John Wiley & Sons A/S.)

In accordance with International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines, six novel, simple and precise sequential spectrophotometric methods were developed and validated for the simultaneous analysis of Ribavirin (RIB), Sofosbuvir (SOF), and Daclatasvir (DAC) in their mixture without prior separation steps. These drugs are described as co-administered for treatment of Hepatitis C virus (HCV). HCV is the cause of hepatitis C and some cancers such as liver cancer (hepatocellular carcinoma) and lymphomas in humans. These techniques consisted of several sequential steps using zero, ratio and/or derivative spectra. DAC was first determined through direct spectrophotometry at 313.7 nm without any interference of the other two drugs while RIB and SOF can be determined after ratio subtraction through five methods; Ratio difference spectrophotometric method, successive derivative ratio method, constant center, isoabsorptive method at 238.8 nm, and mean centering of the ratio spectra (MCR) at 224 nm and 258 nm for RIB and SOF, respectively. The calibration curve is linear over the concentration ranges of (6-42), (10-70) and (4-16) μg/mL for RIB, SOF, and DAC, respectively. This method was successfully applied to commercial pharmaceutical preparation of the drugs, spiked human urine, and spiked human plasma. The above methods are very simple methods that were developed for the simultaneous determination of binary and ternary mixtures and so enhance signal-to-noise ratio. The method has been successfully applied to the simultaneous analysis of RIB, SOF, and DAC in laboratory prepared mixtures. The obtained results are statistically compared with those obtained by the official or reported methods, showing no significant difference with respect to accuracy and precision at p = 0.05., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Measles virus considers an important cause of child morbidity and mortality in some areas as Africa. Ribavirin's activity as a nucleoside analog can disclose the surprisingly broad spectrum action against several RNA viruses under laboratory cell culture conditions. The Current study aimed to investigate the antiviral activity of ribavirin Nano gold particles (AuNPs) against measles virus on vero cell line. Ribavirin- AuNPs was prepared, characterization and the cytotoxicity of ribavirin, AuNPs and ribavirin -AuNPs were tested on vero cells using MTT assay. Antiviral activiry of ribavirin, AuNPs and ribavirin- AuNPswere determined on vero cells using simultaneous, pre-infection and post-infection protocols. Results indicated safety of ribavirin and ribavirin-AuNPs on vero cells, there was a reduction by 78.1% when vero cells treated with ribavirin -AuNPs at 99.5µg/ml while, the viral reduction was 25.4% when ribavirin 500 µg /ml was used for the same viral concentration. Our results concluded that ribavirin - AuNPs had a higher antiviral activity with lower dose than ribavirin alone and the maximal activity showed when it used after the virus infection.

Mayaro fever, caused by Mayaro virus (MAYV) is a sub-lethal disease with symptoms that are easily confused with those of dengue fever, except for polyarthralgia, which may culminate in physical incapacitation. Recently, outbreaks of MAYV have been documented in metropolitan areas, and to date, there is no therapy or vaccine available. Moreover, there is no information regarding the three-dimensional structure of the viral proteins of MAYV, which is important in the search for antivirals. In this work, we constructed a three-dimensional model of protein C of MAYV by homology modelling, and this was employed in a manner similar to that of receptors in virtual screening studies to evaluate 590 molecules as prospective antiviral agents. In vitro bioassays were utilized to confirm the potential antiviral activity of the flavonoid epicatechin isolated from Salacia crassifolia (Celastraceae). The virtual screening showed that six flavonoids were promising ligands for protein C. The bioassays showed potent antiviral action of epicatechin, which protected the cells from almost all of the effects of viral infection. An effective concentration (EC 50 ) of 0.247 μmol/mL was observed with a selectivity index (SI) of 7. The cytotoxicity assay showed that epicatechin has low toxicity, with a 50% cytotoxic concentration (CC 50 ) greater than 1.723 µmol/mL. Epicatechin was found to be twice as potent as the reference antiviral ribavirin. Furthermore, a replication kinetics assay showed a strong inhibitory effect of epicatechin on MAYV growth, with a reduction of at least four logs in virus production. Our results indicate that epicatechin is a promising candidate for further testing as an antiviral agent against Mayaro virus and other alphaviruses.

Rabies remains an invariably fatal neurological disease despite the availability of a preventive vaccination and post-exposure prophylaxis that must be immediately administered to the exposed individual before symptom onset. There is no effective medication for treatment during the symptomatic phase. Ribavirin, a guanine nucleoside analog, is a potent inhibitor of rabies virus (RABV) replication in vitro but lacks clinical efficacy. Therefore, we attempted to identify potential ribavirin analogs with comparable or superior anti-RABV activity. Antiviral activity and cytotoxicity of the compounds were initially examined in human neuroblastoma cells. Among the tested compounds, two exhibited a 5- to 27-fold higher anti-RABV activity than ribavirin. Examination of the anti-RABV mechanisms of action of the compounds using time-of-addition and minigenome assays revealed that they inhibited viral genome replication and transcription. Addition of exogenous guanosine to RABV-infected cells diminished the antiviral activity of the compounds, suggesting that they are involved in guanosine triphosphate (GTP) pool depletion by inhibiting inosine monophosphate dehydrogenase (IMPDH). Taken together, our findings underline the potency of nucleoside analogs as a class of antiviral compounds for the development of novel agents against RABV., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A new Zika virus (ZIKV) outbreak started in 2015. According to the World Health Organization, 84 countries confirmed ZIKV infection. RNA-dependent RNA polymerase (RdRp) was an appealing target for drug designers during the last two decades. Through molecular docking, we screened 16 nucleotide/side inhibitors against ZIKV RdRp. While the mode of interaction with ZIKV is different from that in the hepatitis C virus (HCV), nucleotide/side inhibitors in this study (mostly anti-HCV) showed promising binding affinities (-6.2 to -9.7 kcal/mol calculated by AutoDock Vina) to ZIKV RdRp. Setrobuvir, YAK and, to a lesser extent, IDX-184 reveal promising results compared to other inhibitors in terms of binding ZIKV RdRp. These candidates would be powerful anti-ZIKV drugs.

Macromolecular (pro)drugs hold much promise as broad-spectrum antiviral agents as either microbicides or carriers for intracellular delivery of antiviral drugs. Intriguing opportunity exists in combining the two modes of antiviral activity in the same polymer structure such that the same polymer acts as a microbicide and also serves to deliver the conjugated drug (ribavirin) into the cells. We explore this opportunity in detail and focus on the polymer backbone as a decisive constituent of such formulations. Fourteen polyanions (polycarboxylates, polyphosphates and polyphosphonates, and polysulfonates) were analyzed for blood pro/anti coagulation effects, albumin binding and albumin aggregation, inhibitory activity on polymerases, cytotoxicity, and anti-inflammatory activity in stimulated macrophages. Ribavirin containing monomers were designed to accommodate the synthesis of macromolecular prodrugs with disulfide-exchange triggered drug release. Kinetics of drug release was fast in all cases however enhanced hydrophobicity of the polymer significantly slowed release of ribavirin. Results of this study present a comprehensive view on polyanions as backbone for macromolecular prodrugs of ribavirin as broad-spectrum antiviral agents., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Purpose: Breast cancer is the second most common cause of mortality in women in the United States. Targeted delivery of antitumor breast cancer drugs as a drug-delivery strategy may allow direct delivery into the tumor. Currently, chemotherapy is one of the principle strategies for cancer treatment, but it can have toxic side effects. Nanotechnology attempts to resolve these challenges by loading drugs in nanoparticles, such as solid lipid nanoparticles (SLN). In response to the breast cancer drug 5-fluorouracil (5-FU), p38MAPK signaling has been investigated since the 1990s. Ribavirin, a nucleotide derivative, inhibits p38MAPK in infected hepatocytes. A ribavirin prodrug, taribavirin (TBV), was recently synthesized to concentrate in the liver and have minimal concentration in red blood cells., Methods: In this study, TBV and 5-FU-pegylated SLNs were prepared and characterized. The in vitro cytotoxicity was evaluated against MCF-7 breast cancer cells. Using molecular docking experiments, 5-FU and TBV were docked on p38MAPK protein., Results: The TBV nanoformulation had the highest cytotoxic effects, achieving IC 50  = 0.690 μM after 24 h, compared with free TBV, which also achieved a good cytotoxic effect (IC 50  = 0.756 μM). However, there was a detectable cytotoxic effect and an undetectable IC 50 of 5-FU nanoparticles and free 5-FU on MCF-7 cells., Conclusions: The effect of TBV nanoparticles on MCF-7 cells may be due to its inhibitory effect against p38MAPK protein, where it fits inside the active pocket site of the p38 protein molecular surface, with a minimum binding affinity of -5.5 kcal/mol (rmsd of 1.07), and it formed strong hydrogen bonds with amino acids ASP'168, ILE'166, HIS'148, and ILE'147. Further studies are warranted to investigate the mechanistic details of the proposed approach.

This study reports a novel and efficient method for the synthesis of the first reported novel class of triazole thioglycosides. These series of compounds were designed through the reaction of potassium cyanocarbonimidodithioate 2 with hydrazine derivatives 3a-d in EtOH at room temperature to give the corresponding potassium 5-amino-1H-1,2,4-triazole-3-thiolates 4a-d. The latter compounds were treated with tetra-O-acetyl-α-D-glucopyranosyl bromide 6a and tetra-O-acetyl-α-D-galactopyranosyl bromide 6b in DMF at room temperature to give in high yields the corresponding triazole thioglycosides 7a-h. Treatment of triazole salts 4a-d with hydrochloric acid afforded the corresponding 3-mercaptotriazoles 5a-d. Compounds 5a-d were then reacted with bromoperacetylated sugars 6a,b in sodium hydride-DMF at ambient temperature to afford the thioglycosyl compounds 7a-h. Ammonolysis of the triazole thioglycosides 7a-h afforded the corresponding free thioglycosides 8a-h. The scope and limitation of the method is demonstrated. The structure of the reaction products was confirmed on the basis of their elemental analysis and spectral data (IR, 1 H NMR, MS and 13 C NMR).

Chikungunya virus (CHIKV) is a mosquito-borne virus that has recently emerged in the Western Hemisphere. Approved antiviral therapies or vaccines for the treatment or prevention of CHIKV infections are not available. This study aims to evaluate the antiviral activity of commercially available broad-spectrum antivirals against CHIKV. Due to host cell-specific variability in uptake and intracellular processing of drug, we evaluated the antiviral effects of each agent in three cell lines. Antiviral activities of ribavirin (RBV), interferon-alfa (IFN-α) and favipiravir (FAV) were assessed in CHIKV-infected Vero, HUH-7, and A549 cells. CHIKV-infected cells were treated with increasing concentrations of each agent for three days and viral burden was quantified by plaque assay on Vero cells. Cytotoxic effects of RBV, FAV and IFN-α were also evaluated. Antiviral activity differed depending on the cell line used for evaluation. RBV had the greatest antiviral effect in HUH-7 cells (EC 50  = 2.575 µg/mL); IFN-α was most effective in A549 cells (EC 50  = 4.235 IU/mL); and FAV in HUH-7 cells (EC 50  = 20.00 μg/mL). The results of our study show FAV and IFN-α are the most promising candidates, as their use led to substantial reductions in viral burden at clinically achievable concentrations in two human-derived cell lines. FAV is an especially attractive candidate for further investigation due to its oral bioavailability. These findings also highlight the importance of cell line selection for preclinical drug trials.

Growing resistance in malarial parasites, particularly in Plasmodium falciparum needs a serious search for the discovery of novel drug targets. Inosine monophosphate dehydrogenase (IMPDH) is an important target for antimalarial drug discovery process in P. falciparum for the treatment of malaria. In the absence of x-ray crystal structure of this enzyme, homology modeling proved to be a reasonable alternate to study substrate binding mechanisms of this enzyme. In this study, a 3-D homology model for P. falciparum IMPDH was constructed taking human IMPDH (PDB code 1NF7) as template. Furthermore, an in-silico combinatorial library of ribavirin (RVP) derivatives (1347 molecules) was designed and virtually screened for ligands having selectively greater binding affinity with Plasmodium falciparum IMPDH relative to human IMPDH II. A total of five Ribavirin derivatives were identified as having greater binding affinity (-126 to -108Kcal/mol and -9.4 to -8.6Kcal/mol) with Plasmodium falciparum IMPDH. These five inhibitors should be used as selective and potent for Plasmodium falciparum IMPDH. Such type of study will provide information to synthetic medicinal chemist to enhance the potential of compounds (RVP derivatives) as chemotherapeutic agents to fight against the increasing burden of malarial infections., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Aims Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne infectious disease. SFTS is epidemic in Asia, and its fatality rate is around 30% in Japan. The causative virus severe fever with thrombocytopenia syndrome virus (SFTSV) is a phlebovirus of the family Phenuiviridae (the order Bunyavirales). Although effective treatments are required, there are no antiviral agents currently approved for clinical use. Ribavirin and favipiravir were examined for their anti-SFTSV activity and found to be selective inhibitors of SFTSV replication in vitro. However, their activity was not sufficient. Therefore, it is mandatory to identify novel compounds active against SFTSV. To this end, we have established a safe and rapid assay system for screening selective inhibitors of SFTSV. Methods The virus was isolated from SFTS patients treated in Kagoshima University Hospital. Vero cells were infected with SFTSV and incubated in the presence of various concentrations of test compounds. After three days, the cells were examined for their intracellular viral RNA levels by real-time reverse transcription-PCR without extracting viral RNA. The cytotoxicity of test compounds was determined by a tetrazolium dye method. Results Among the test compounds, the antimalarial agent amodiaquine was identified as a selective inhibitor of SFTSV replication. Its 50% effective concentration (EC 50 ) and cytotoxic concentration (CC 50 ) were 19.1 ± 5.1 and >100 µM, respectively. The EC 50 value of amodiaquine was comparable to those of ribavirin and favipiravir. Conclusion Amodiaquine is considered to be a promising lead of novel anti-SFTSV agents, and evaluating the anti-SFTSV activity of its derivatives is in progress.

Ribavirin (C 8 H 12 N 4 O 5 ; anti-viral agent) was crystallized as two unique, phase-pure polymorphs (R-I and R-II). Calorimetrically determined isobaric heat capacities and heat of transition data were utilized to determine the solid-state transition temperature (T tr ), confirming enantiotropism, while R-I was determined to be kinetically stable at ambient temperature. Unprocessed samples of the low T m polymorph, R-II, did not convert into R-I when held isothermally well above T tr for 7days. In contrast milled R-II completely transformed to R-I after 15min at the same storage conditions, indicating that defects sustained during processing reduced the energy barrier for transformation, allowing it to occur. R-II was subjected to both cryogenic milling and impact milling at ambient temperature for various durations. Cryomilling resulted in an in situ progressive reduction of crystallinity, with complete conversion to amorphous ribavirin after 2h. Limited molecular mobility attributable to the low milling temperature (T exp =-196°C) likely inhibited recrystallization, allowing the amorphous solid to persist. In contrast, continuous impact milling at ambient temperature resulted in complete in situ conversion from R-II to R-I after 3h. The data suggested rapid conversion to R-I from highly disordered regions during extended milling, facilitated by localized heat buildup that likely exceeded T g and/or T tr ., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Novel direct-acting antiviral DAA combination therapies tremendously improved sustained virologic response (SVR) rates in patients with chronic HCV infection. SVR is typically accompanied by normalization of liver enzymes, however, hepatic inflammation, i.e. persistently elevated aminotransferase levels may persist despite HCV eradication. Aim: To investigate prevalence and risk factors for ongoing hepatic inflammation after SVR in two large patient cohorts., Methods: This post-hoc analysis was based on prospectively collected demographic and clinical data from 834 patients with SVR after HCV treatment with either PegIFN- or DAA-based treatment regimens from the PRAMA trial (n = 341) or patients treated at our outpatient clinic (n = 493)., Results: We observed an unexpected high prevalence of post-SVR inflammation, including patients who received novel IFN-free DAA-based therapies. Up to 10% of patients had ongoing elevation of aminotransferase levels and another 25% showed aminotransferase activity above the so-called healthy range. Several baseline factors were independently associated with post-SVR aminotransferase elevation. Among those, particularly male gender, advanced liver disease and markers for liver steatosis were strongly predictive for persistent ALT elevation. The use of IFN-based antiviral treatment was independently correlated with post-SVR inflammation, further supporting the overall benefit of IFN-free combination regimens., Conclusion: This is the first comprehensive study on a large patient cohort investigating the prevalence and risk factors for ongoing liver inflammation after eradication of HCV. Our data show a high proportion of patients with ongoing hepatic inflammation despite HCV eradication with potential implications for the management of approximately one third of all patients upon SVR., Competing Interests: S.Z. has served as a consultant for AbbVie, Bristol-Myers Squibb, Gilead Sciences, Merck, and Janssen. T.M.W. has consultancies for AbbVie, Boehringer-Ingelheim, Gilead, Janssen, and Novartis. All other authors declare no competing interests. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Upregulation of eIF4E is associated with poor clinical outcome in many human cancers and represents a potential therapeutic target. However, the function of eIF4E remains unknown in oral tongue squamous cell carcinoma (OTSCC). In this work, we show that ribavirin, an anti-viral drug, effectively augments sensitivity of OTSCC cells to paclitaxel via inhibiting mTOR/eIF4E signaling pathway. Ribavirin dose-dependently inhibits proliferation and induces apoptosis in SCC-9 and CAL27 cells. Combination of ribavirin and paclitaxel are more effective in inhibiting proliferation and inducing apoptosis in OTSCC cells. Importantly, the in vivo efficacy of ribavirin and its synergism with paclitaxel is confirmed by two independent OTSCC xenograft mouse models. Mechanistically, ribavirin significantly decreases mTOR/eIF4E signaling pathway in OTSCC cells via suppressing phosphorylation of Akt, mTOR, 4EBP1 and eIF4E. Overexpression of the phosphor-mimetic form of eIF4E (eIF4E S209D) but not the nonphosphorylatable form (eIF4E S209A) reverses the effects of ribavirin, confirming that eIF4E inhibition is the mechanism of action of ribavirin in OTSCC cells. In addition, eIF4E depletion significantly enhances the anti-proliferative and pro-apoptotic effects of paclitaxel, demonstrating the critical role of eIF4E in OTSCC cell response to paclitaxel. Our work is the first to demonstrate the efficacy of ribavirin as a single agent and synergism as combination with paclitaxel in OTSCC in vitro and in vivo. Our findings also demonstrate the therapeutic value of inhibiting eIF4E in OTSCC treatment., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The requirement for new antiviral therapeutics is an ever present need. Particularly lacking are broad spectrum antivirals that have low toxicity. We develop such agents based on macromolecular prodrugs whereby both the polymer chain and the drug released from the polymer upon cell entry have antiviral effects. Specifically, macromolecular prodrugs were designed herein based on poly(methacrylic acid) and ribavirin. Structure-function parameter space was analyzed via the synthesis of 10 polymer compositions varied by molar mass and drug content. Antiviral activity was tested in cell culture against both low and high pathogenic strains of influenza. Lead compounds were successfully used to counter infectivity of influenza in chicken embryos. The lead composition with the highest activity against influenza was also active against another respiratory pathogen, respiratory syncytial virus, providing opportunity to potentially treat infection by the two pathogens with one antiviral agent. In contrast, structure-function activity against the herpes simplex virus was drastically different, revealing limitations of the broad spectrum antiviral agents based on macromolecular prodrugs.

The primary aim of this study was to investigate ribavirin solution for inhalation stability under three different conditions (frozen, refrigerated, room temperature) over a 45-day period. A ribavirin 6000-mg vial was reconstituted with 90 mL of Sterile Water for Injection per the package insert to yield a concentration of approximately 67 mg/mL. The solution was then placed in either syringes or empty glass vials and stored in the freezer (-20°C), in the refrigerator (~0°C to 4°C), or at room temperature (~20°C to 25°C). Original concentrations were measured on day 0 and subsequent concentrations were measured on day 2, 14, and 45 utilizing a validated liquid chromatography with tandem mass spectrometry assay. All analyses were performed in triplicate for each storage condition. Additionally, at each time point the physical stability was evaluated and the pH of solution was measured. The solution was considered stable if =90% of the original concentration was retained over the study period. A validated liquid chromatography with tandem mass spectrometry analysis demonstrated that &gt;95% of the original ribavirin concentration was preserved over the 45-day period for all study conditions. The ribavirin concentration remained within the United States Pharmacopeia (USP)-required range of 95% to 105% of the original labeled product amount throughout the entire study period for all study conditions. Precipitation of ribavirin was noted during the thawing cycle for frozen samples, but the drug went back into solution once the thawing process was completed. No changes in color or turbidity were observed in any of the prepared solutions. Values for pH remained stable over the study period and ranged from 4.1 to 5.3. Ribavirin for inhalation solution is physically and chemically stable for at least 45 days when frozen, refrigerated, or kept at room temperature after reconstitution to a concentration of approximately 67 mg/mL and placed in syringes or glass vials., (Copyright© by International Journal of Pharmaceutical Compounding, Inc.)

T-705 (favipiravir) is a new antiviral agent in advanced clinical development for influenza therapy. It is supposed to act as an alternative substrate for the viral polymerase, causing inhibition of viral RNA synthesis or virus mutagenesis. These mechanisms were also proposed for ribavirin, an established and broad antiviral drug that shares structural similarity with T-705. We here performed a comparative analysis of the effects of T-705 and ribavirin on influenza virus and host cell functions. Influenza virus-infected cell cultures were exposed to T-705 or ribavirin during single or serial virus passaging. The effects on viral RNA synthesis and infectious virus yield were determined and mutations appearing in the viral genome were detected by whole-genome virus sequencing. In addition, the cellular nucleotide pools as well as direct inhibition of the viral polymerase enzyme were quantified. We demonstrate that the anti-influenza virus effect of ribavirin is based on IMP dehydrogenase inhibition, which results in fast and profound GTP depletion and an imbalance in the nucleotide pools. In contrast, T-705 acts as a potent and GTP-competitive inhibitor of the viral polymerase. In infected cells, viral RNA synthesis is completely inhibited by T-705 or ribavirin at ≥50 μM, whereas exposure to lower drug concentrations induces formation of noninfectious particles and accumulation of random point mutations in the viral genome. This mutagenic effect is 2-fold higher for T-705 than for ribavirin. Hence, T-705 and ribavirin both act as purine pseudobases but profoundly differ with regard to the mechanism behind their antiviral and mutagenic effects on influenza virus., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

This study describes HSA binding properties of a platinum(II) complex with an antiviral drug ligand; ribavirin. Spectroscopic analysis of the emission quenching at different temperatures and UV-vis spectra revealed that the quenching mechanism of HSA by Pt(II) complex is static quenching mechanism. The binding constants and the number of binding sites were determined by fluorescence quenching method. Pt(II) complex binding is characterized by one high affinity binding site. Through the site marker competitive experiment, site I was assigned to possess high affinity binding site for Pt(II) complex. The calculated thermodynamic parameters (ΔG, ΔH and ΔS) confirmed that the binding reaction is spontaneous, and hydrophobic forces played a major role in the reaction. Fluorescence quenching studies showed that the binding affinity of Pt(II) complex with HSA in the buffer solution at different pH values is: Kb (pH3.0)>Kb (pH9.0)>Kb (pH7.4). The CD spectrum shows the binding of Pt(II) complex leads to a change in the α-helical structure of HSA. CD spectroscopy studies further indicated the influence of pH on the complexation process and the alteration in the protein conformation upon binding., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release solid oral dosage forms containing ribavirin are reviewed. Ribavirin is highly soluble, but its permeability characteristics are not well defined. Therefore according to the Biopharmaceutical Classification System, and taking a "worst case" approach, ribavirin should be assigned to class III. As ribavirin is transported across the brush border membrane of the human jejunum by hCNT2, it shows saturable uptake in the intestine. However, no common excipients have been shown to compete for ribavirin absorption, nor have problems with BE of immediate release ribavirin formulations containing different excipients and produced by different manufacturing methods been reported in the open literature. So the risk of bioinequivalence caused by these factors appears to be low. Ribavirin is considered a narrow therapeutic index drug, as judged by comparing the minimum effective concentration and minimum toxic concentrations in blood. Although ribavirin would not be eligible for approval via a Biopharmaceutical Classification System-based biowaiver procedure according to today's guidances due to its narrow therapeutic index, the risks of biowaiving should be weighed against the considerable risks associated with studying BE of ribavirin products in healthy subjects., (Copyright © 2016 American Pharmacists Association®. All rights reserved.)

The hepatitis C virus (HCV) RNA-dependent RNA-polymerase NS5B is essentially required for viral replication and serves as a prominent drug target. Sofosbuvir is a prodrug of a nucleotide analog that interacts selectively with NS5B and has been approved for HCV treatment in combination with ribavirin. Although the emergence of resistance to sofosbuvir is rarely seen in the clinic, the S282T mutation was shown to decrease susceptibility to this drug. S282T was also shown to confer hypersusceptibility to ribavirin, which is of potential clinical benefit. Here we devised a biochemical approach to elucidate the underlying mechanisms. Recent crystallographic data revealed a hydrogen bond between S282 and the 2'-hydroxyl of the bound nucleotide, while the adjacent G283 forms a hydrogen bond with the 2'-hydroxyl of the residue of the template that base pairs with the nucleotide substrate. We show that DNA-like modifications of the template that disrupt hydrogen bonding with G283 cause enzyme pausing with natural nucleotides. However, the specifically introduced DNA residue of the template reestablishes binding and incorporation of sofosbuvir in the context of S282T. Moreover, the DNA-like modifications of the template prevent the incorporation of ribavirin in the context of the wild-type enzyme, whereas the S282T mutant enables the binding and incorporation of ribavirin under the same conditions. Together, these findings provide strong evidence to show that susceptibility to sofosbuvir and ribavirin depends crucially on a network of interdependent hydrogen bonds that involve the adjacent residues S282 and G283 and their interactions with the incoming nucleotide and complementary template residue, respectively., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Synthesis of three tiazofurin (1) isosteres with nitrogen functionalities at the C-2' position (N3, NH2 and NH3(+)Cl(-)) has been achieved, in multistep sequences, starting from monoacetone d-glucose. A number of potential bioisosteres of 1 bearing acylamido functions at the C-2' position have also been synthesized from the same sugar precursor. In vitro cytotoxicities of target molecules against a number of human tumour cell lines were recorded and compared with those observed for lead molecule 1. Some of the synthesized compounds showed potent in vitro antitumour activity, such as 2'-azido derivative 2, which is the most potent of all molecules under evaluation (IC50 0.004 μM against MCF-7 cells). Flow cytometry data suggest that cytotoxic effects of these compounds in the culture of K562 cells might be mediated by apoptosis, additionally revealing that these molecules induced changes in cell cycle distribution of these cells. Results of Western blot analysis indicate that the synthesized tiazofurin analogues induce apoptosis in a caspase-dependent way., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

Macromolecular prodrugs are developed as multiarmed agents against diverse viral pathogens. Lead candidates inhibit infectivity and replication of HIV, Ebola, influenza, measles, RSV, etc-thus being broad-spectrum antiviral agents., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: The phenanthroindolizidine alkaloid antofine and its analogues have excellent antiviral activity against tobacco mosaic virus (TMV). To simplify the structure and the synthesis of the phenanthroindolizidine alkaloid, a series of phenanthrene-containing N-heterocyclic compounds (compounds 1 to 33) were designed and synthesised, based on the intermolecular interaction of antofine and TMV RNA, and systematically evaluated for their anti-TMV activity., Result: Most of these compounds exhibited good to reasonable anti-TMV activity. The optimum compounds 5, 12 and 21 displayed higher activity than the lead compound antofine and commercial ribavirin. Compound 12 was chosen for field trials of antiviral efficacy against TMV, and was found to exhibit better activity than control plant virus inhibitors. Compounds 5 and 12 were chosen for mode of action studies. The changes in fluorescence intensity of compounds 5 and 12 on separated TMV RNA showed that these small molecules can also bind to TMV RNA, but the mode is very different from that of antofine., Conclusion: The compounds combining phenanthrene and an N-heterocyclic ring could maintain the anti-TMV activity of phenanthroindolizidines, but their modes of action are different from that of antofine. The present study lays a good foundation for us to find more efficient anti-plant virus reagents., (© 2015 Society of Chemical Industry.)

We report the first successful implementation of transfection agents to facilitate the delivery of non-nucleic acid based anti-inflammatory and anti-viral drugs. In doing so, we illustrate a new paradigm in the intracellular delivery of polyanionic drugs and also extend the scope and utility of successful tools of gene transfer into a new area of biomedical research.

Myxoviruses such as influenza A virus (IAV) and respiratory syncytial virus (RSV) are major human pathogens, mandating the development of novel therapeutics. To establish a high-throughput screening protocol for the simultaneous identification of pathogen- and host-targeted hit candidates against either pathogen or both, we have attempted co-infection of cells with IAV and RSV. However, viral replication kinetics were incompatible, RSV signal window was low, and an IAV-driven minireplicon reporter assay used in initial screens narrowed the host cell range and restricted the assay to single-cycle infections. To overcome these limitations, we developed an RSV strain carrying firefly luciferase fused to an innovative universal small-molecule assisted shut-off domain, which boosted assay signal window, and a hyperactive fusion protein that synchronized IAV and RSV reporter expression kinetics and suppressed the identification of RSV entry inhibitors sensitive to a recently reported RSV pan-resistance mechanism. Combined with a replication-competent recombinant IAV strain harboring nanoluciferase, the assay performed well on a human respiratory cell line and supports multicycle infections. Miniaturized to 384-well format, the protocol was validated through screening of a set of the National Institutes of Health Clinical Collection (NCC) in quadruplicate. These test screens demonstrated favorable assay parameters and reproducibility. Application to a LOPAC library of bioactive compounds in a proof-of-concept campaign detected licensed antimyxovirus therapeutics, ribavirin and the neuraminidase inhibitor zanamivir, and identified two unexpected RSV-specific hit candidates, Fenretinide and the opioid receptor antagonist BNTX-7. Hits were evaluated in direct and orthogonal dose-response counterscreens using a standard recRSV reporter strain expressing Renilla luciferase.

Ribavirin is used to treat hepatitis C but causes serious hemolytic anemia. The objective of the study was to develop a ribavirin prodrug to achieve liver-specific drug delivery and to reduce its off-target effect in red blood cells (RBCs). The approach aimed to target the human sodium taurocholate cotransporting polypeptide (NTCP), which is a bile acid transporter predominately expressed in the liver. Six prodrugs with ribavirin conjugation at C-3 or C-24 of the bile acids were synthesized. In vitro uptake studies indicated that all six prodrugs were NTCP substrates. Metabolic studies in vitro indicated that ribavirin-l-Val-glycochenodeoxycholic acid (GCDCA) was able to release ribavirin in the mouse liver S9 fraction. Additionally, in vitro studies showed that ribavirin in RBC was reduced by 16.7-fold from prodrug compared with parent drug incubation. Moreover, almost no prodrug was present in RBC. In vivo study in mice also showed that ribavirin-l-Val-GCDCA could provide almost the same ribavirin exposure in the liver as ribavirin administration, but with about 1.8-fold less exposure of ribavirin in RBC, plasma, and kidney. Overall, the study suggested that ribavirin-l-Val-GCDCA has the potential to achieve ribavirin-specific liver delivery., (© 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.)

Ribavirin is a nucleoside which is used as an antiviral agent against both RNA and DNA viruses. However, accumulation in erythrocytes causes hemolysis which limits its usefulness. To minimize ribavirin-induced hemolysis and increase its antiviral effect, considerable efforts have been made involving chemical prodrugs and various formulations. Combination with macromolecules to achieve better targeting and increased uptake is one of the most promising strategies. In addition, decreasing the association with RBCs through prodrugs and delivery systems is considered. This review summarizes prodrugs and delivery systems for ribavirin and, at the same time examines these different strategies. Moreover, a novel design of prodrug is proposed for further study., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Dual or triple combination regimens of novel hepatitis C direct-acting antivirals (DAA, daclatasvir, asunaprevir, or beclabuvir) provide high sustained virological response rates and reduced frequency of resistance compared to clinical monotherapy. To support pharmacokinetic (PK) assessments in clinical studies, a multiplexed liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantitation of daclatasvir, asunaprevir, beclabuvir (BMS-791325) and its active metabolite (BMS-794712) in human plasma was developed and validated. Human plasma samples were extracted with methyl-t-butyl ether followed by an LC-MS/MS analysis, which was conducted in a multiple reaction monitoring (MRM) mode. The lower limits of quantitation (LLOQ) were 1 ng/mL for daclatasvir, asunaprevir, and BMS-794712, and 2 ng/mL for beclabuvir. Intra-run precision (≤4.5% CV), inter-run precision (≤2.9% CV), and accuracy (±5.3% deviation) based on different concentration levels (low, geometric mean, mid and high) of the quality control samples (QCs) provided evidence of the methods accuracy and precision. Selectivity and matrix effect on LC-MS/MS detection, stability in plasma, and potential interference of coadministered drugs (ribavirin and interferon) were all evaluated and the results were acceptable. Method reproducibility was demonstrated by the reanalysis of a portion of study samples. The cross-validation results for QCs demonstrated the equivalency between this method and two single-analyte methods which were previously validated for quantitation of daclatasvir in human plasma. This approach of using a multiplexed LC-MS/MS method for the simultaneous quantitation of three DAAs is time- and cost-effective, and can maintain good data quality in sample analysis., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Ribavirin (RBV) is a nucleoside analog used to treat a variety of DNA and RNA viruses. RBV undergoes intracellular phosphorylation to a mono- (MP), di- (DP), and triphosphate (TP). The phosphorylated forms have been associated with the mechanisms of antiviral effect observed in vitro, but the intracellular pharmacology of the drug has not been well characterized in vivo. A highly sensitive LC-MS/MS method was developed and validated for the determination of intracellular RBV MP, DP, and TP in multiple cell matrix types. For this method, the individual MP, DP, and TP fractions were isolated from lysed intracellular matrix using strong anion exchange solid phase extraction, dephosphorylated to parent RBV, desalted and concentrated and quantified using LC-MS/MS. The method utilized a stable labeled internal standard (RBV-(13)C5) which facilitated accuracy (% deviation within ±15%) and precision (coefficient of variation of ≤15%). The quantifiable linear range for the assay was 0.50 to 200 pmol/sample. The method was applied to the measurement of RBV MP, DP, and TP in human peripheral blood mononuclear cells (PBMC), red blood cells (RBC), and dried blood spot (DBS) samples obtained from patients taking RBV for the treatment of chronic Hepatitis C virus infection., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Efficacious, potent, and at the same time nontoxic macromolecular prodrugs of ribavirin are designed taking advantage over prodrug activation by the intracellular milieu. Activity of these prodrugs is illustrated in the cells hosting hepatitis C virus replication and also in the cells implicated in the inflammatory response to the viral infection., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We have studied processes of copper(II) ion binding by ribavirin, an antiviral agent used in treating hepatitis C, which is accompanied usually by an increased copper level in the serum and liver tissue. Protonation equilibria and Cu(II) binding were investigated using the UV-visible, EPR and NMR spectroscopic techniques as well as the DFT (density functional theory) calculations. The spectroscopic data suggest that the first complex is formed in the water solution at pH as low as 0.5. In this compound Cu(II) ion is bound to one of the nitrogen atoms from the triazole ring. Above pH6.0, the metal ion is surrounded by two nitrogen and two oxygen atoms from two ligand molecules. The DFT calculations allowed to determine the exact structure of this complex. We found that in the lowest energy isomer two molecules of the ligand coordinate via O and N4 atoms in trans positions. The hypothetical oxidative properties of the investigated system were also examined. It proved not to generate plasmid DNA scission products. However, the calf thymus (CT)-DNA binding studies showed that it reacts with ribavirin and its cupric complex. Moreover, the interaction with the complex is much more efficient., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Ribavirin is an antiviral drug used for the treatment of chronic hepatitis C. However, ribavirin induces severe side effects such as hemolytic anemia. In this study, we prepared biodegradable nanoparticles as ribavirin carriers to modulate the pharmacokinetics of the drug. The nanoparticles encapsulating ribavirin monophosphate (RMP) were prepared from the blend of poly(d,l-lactic acid) homopolymer and arabinogalactan (AG)-poly(l-lysine) conjugate by using the solvent diffusion method in the presence of iron (III). RMP was efficiently and stably embedded in the nanoparticles and gradually released for 37 days in phosphate-buffered saline at 37°C. The coating of AG on the nanoparticles surfaces was verified by measuring the zeta potentials and performing an aggregation test of the nanoparticles using galactose-binding lectin. Moreover, the nanoparticles were efficiently internalized in cultured HepG2 cells. Ribavirin was drastically accumulated to the liver of mice after intravenous administration of the RMP-loaded nanoparticles, after which the ribavirin content gradually decreased for at least 7 days. Our results indicated successful development of nanoparticles with dual functions, targeting to the liver and sustained release of ribavirin, and suggested that the present strategy could help to advance the clinical application of ribavirin as a therapeutic agent for chronic hepatitis C., (© 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.)

Polymers in tune. Automated parallel polymer synthesis is developed to obtain libraries of macromolecular prodrugs of ribavirin, a broad-spectrum antiviral agent. As many as 10 identified lead polymer conjugates exhibit therapeutic efficacy matching that of the pristine drug and at the same time suppressed the origin of the main side effect of ribavirin., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)