Publications by authors named "Salvatore Ferla"

40 Publications

Concise synthesis and biological evaluation of 2-Aryl-3-Anilinobenzo[b]thiophene derivatives as potent apoptosis-inducing agents.

Bioorg Chem 2021 Jul 20;112:104919. Epub 2021 Apr 20.

Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, 44121 Ferrara, Italy.

Many clinically used agents active in cancer chemotherapy exert their activity through the induction of cell death (apoptosis) by targeting microtubules, altering protein function or inhibiting DNA synthesis. The benzo[b]thiophene scaffold holds a pivotal place as a pharmacophore for the development of anticancer agents, and, in addition, this scaffold has many pharmacological activities. We have developed a flexible method for the construction of a new series of 2-aryl-3-(3,4,5-trimethoxyanilino)-6-methoxybenzo[b]thiophenes as potent antiproliferative agents, giving access to a wide range of substitution patterns at the 2-position of the 6-methoxybenzo[b]thiophene common intermediate. In the present study, all the synthesized compounds retained the 3-(3,4,5-trimethoxyanilino)-6-methoxybenzo[b]thiophene moiety, and the structure-activity relationship was examined by modification of the aryl group at its 2-position with electron-withdrawing (F) or electron-releasing (alkyl and alkoxy) groups. We found that small substituents, such as fluorine or methyl, could be placed in the para-position of the 2-phenyl ring, and these modifications only slightly reduced antiproliferative activity relative to the unsubstituted 2-phenyl analogue. Compounds 3a and 3b, bearing the phenyl and para-fluorophenyl at the 2-position of the 6-methoxybenzo[b]thiophene nucleus, respectively, exhibited the greatest antiproliferative activity among the tested compounds. The treatment of both Caco2 (not metastatic) and HCT-116 (metastatic) colon carcinoma cells with 3a or 3b triggered a significant induction of apoptosis as demonstrated by the increased expression of cleaved-poly(ADP-ribose) polymerase (PARP), receptor-interacting protein (RIP) and caspase-3 proteins. The same effect was not observed with non-transformed colon 841 CoN cells. A potential additional effect during mitosis for 3a in metastatic cells and for 3b in non-metastatic cells was also observed.
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http://dx.doi.org/10.1016/j.bioorg.2021.104919DOI Listing
July 2021

Targeting the Complement Serine Protease MASP-2 as a Therapeutic Strategy for Coronavirus Infections.

Viruses 2021 02 17;13(2). Epub 2021 Feb 17.

Department of Chemistry, College of Science and Engineering, Swansea University, Swansea SA28PP, UK.

MASP-2, mannose-binding protein-associated serine protease 2, is a key enzyme in the lectin pathway of complement activation. Hyperactivation of this protein by human coronaviruses SARS-CoV, MERS-CoV and SARS-CoV-2 has been found to contribute to aberrant complement activation in patients, leading to aggravated lung injury with potentially fatal consequences. This hyperactivation is triggered in the lungs through a conserved, direct interaction between MASP-2 and coronavirus nucleocapsid (N) proteins. Blocking this interaction with monoclonal antibodies and interfering directly with the catalytic activity of MASP-2, have been found to alleviate coronavirus-induced lung injury both in vitro and in vivo. In this study, a virtual library of 8736 licensed drugs and clinical agents has been screened in silico according to two parallel strategies. The first strategy aims at identifying direct inhibitors of MASP-2 catalytic activity, while the second strategy focusses on finding protein-protein interaction inhibitors (PPIs) of MASP-2 and coronaviral N proteins. Such agents could represent promising support treatment options to prevent lung injury and reduce mortality rates of infections caused by both present and future-emerging coronaviruses. Forty-six drug repurposing candidates were purchased and, for the ones selected as potential direct inhibitors of MASP-2, a preliminary in vitro assay was conducted to assess their interference with the lectin pathway of complement activation. Some of the tested agents displayed a dose-response inhibitory activity of the lectin pathway, potentially providing the basis for a viable support strategy to prevent the severe complications of coronavirus infections.
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http://dx.doi.org/10.3390/v13020312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923061PMC
February 2021

A facile synthesis of diaryl pyrroles led to the discovery of potent colchicine site antimitotic agents.

Eur J Med Chem 2021 Mar 29;214:113229. Epub 2021 Jan 29.

Istituto di Ricerca Pediatrica (IRP), Corso Stati Uniti 4, 35128, Padova, Italy. Electronic address:

Three different series of cis-restricted analogues of combretastatin A-4 (CA-4), corresponding to thirty-nine molecules that contained a pyrrole nucleus interposed between the two aryl rings, were prepared by a palladium-mediated coupling approach and evaluated for their antiproliferative activity against six human cancer cell lines. In the two series of 1,2-diaryl pyrrole derivatives, results suggested that the presence of the 3',4',5'-trimethoxyphenyl moiety at the N-1 position of the pyrrole ring was more favorable for antiproliferative activity. In the series of 3,4-diarylpyrrole analogues, three compounds (11i-k) exhibited maximal antiproliferative activity, showing excellent antiproliferative activity against the CA-4 resistant HT-29 cells. Inhibition of tubulin polymerization of selected 1,2 pyrrole derivatives (9a, 9c, 9o and 10a) was similar to that observed with CA-4, while the isomeric 3,4-pyrrole analogues 11i-k were generally from 1.5- to 2-fold more active than CA-4. Compounds 11j and 11k were the only compounds that showed activity as inhibitors of colchicine binding comparable to that CA-4. Compound 11j had biological properties consistent with its intracellular target being tubulin. This compound was able to block the cell cycle in metaphase and to induce significant apoptosis at a concentration of 25 nM, following the mitochondrial pathway, with low toxicity for normal cells. More importantly, compound 11j exerted activity in vivo superior to that of CA-4P, being able to significantly reduce tumor growth in a syngeneic murine tumor model even at the lower dose tested (5.0 mg/kg).
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http://dx.doi.org/10.1016/j.ejmech.2021.113229DOI Listing
March 2021

Rational design of highly potent broad-spectrum enterovirus inhibitors targeting the nonstructural protein 2C.

PLoS Biol 2020 11 6;18(11):e3000904. Epub 2020 Nov 6.

Virology Section, Infectious Disease and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.

There is a great need for antiviral drugs to treat enterovirus (EV) and rhinovirus (RV) infections, which can be severe and occasionally life-threatening. The conserved nonstructural protein 2C, which is an AAA+ ATPase, is a promising target for drug development. Here, we present a structure-activity relationship study of a previously identified compound that targets the 2C protein of EV-A71 and several EV-B species members, but not poliovirus (PV) (EV-C species). This compound is structurally related to the Food and Drug Administration (FDA)-approved drug fluoxetine-which also targets 2C-but has favorable chemical properties. We identified several compounds with increased antiviral potency and broadened activity. Four compounds showed broad-spectrum EV and RV activity and inhibited contemporary strains of emerging EVs of public health concern, including EV-A71, coxsackievirus (CV)-A24v, and EV-D68. Importantly, unlike (S)-fluoxetine, these compounds are no longer neuroactive. By raising resistant EV-A71, CV-B3, and EV-D68 variants against one of these inhibitors, we identified novel 2C resistance mutations. Reverse engineering of these mutations revealed a conserved mechanism of resistance development. Resistant viruses first acquired a mutation in, or adjacent to, the α2 helix of 2C. This mutation disrupted compound binding and provided drug resistance, but this was at the cost of viral fitness. Additional mutations at distantly localized 2C residues were then acquired to increase resistance and/or to compensate for the loss of fitness. Using computational methods to identify solvent accessible tunnels near the α2 helix in the EV-A71 and PV 2C crystal structures, a conserved binding pocket of the inhibitors is proposed.
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http://dx.doi.org/10.1371/journal.pbio.3000904DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673538PMC
November 2020

Computational Studies towards the Identification of Novel Rhodopsin-Binding Compounds as Chemical Chaperones for Misfolded Opsins.

Molecules 2020 Oct 23;25(21). Epub 2020 Oct 23.

Department of Chemistry, Swansea University, Swansea SA2 8PP, UK.

Accumulation of misfolded and mistrafficked rhodopsin on the endoplasmic reticulum of photoreceptor cells has a pivotal role in the pathogenesis of retinitis pigmentosa and a subset of Leber's congenital amaurosis. One potential strategy to reduce rhodopsin misfolding and aggregation in these conditions is to use opsin-binding compounds as chemical chaperones for opsin. Such molecules have previously shown the ability to aid rhodopsin folding and proper trafficking to the outer cell membranes of photoreceptors. As means to identify novel chemical chaperones for rhodopsin, a structure-based virtual screening of commercially available drug-like compounds (300,000) was performed on the main binding site of the visual pigment chromophore, the 11--retinal. The best 24 virtual hits were examined for their ability to compete for the chromophore-binding site of opsin. Among these, four small molecules demonstrated the ability to reduce the rate constant for the formation of the 9--retinal-rhodopsin complex, while five molecules surprisingly enhanced the formation of this complex. Compound , , and showed a weak but detectable increase in the trafficking of the P23H mutant, widely used as a model for both retinitis pigmentosa and Leber's congenital amaurosis, from the ER to the cell membrane. The compounds did not show any relevant cytotoxicity in two different human cell lines, with the only exception of . Based on the structures of these active compounds, a series of in silico studies gave important insights on the potential structural features required for a molecule to act either as chemical chaperone or as stabiliser of the 11--retinal-rhodopsin complex. Thus, this study revealed a series of small molecules that represent a solid foundation for the future development of novel therapeutics against these severe inherited blinding diseases.
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http://dx.doi.org/10.3390/molecules25214904DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7660337PMC
October 2020

Design, synthesis, in vitro and in vivo biological evaluation of 2-amino-3-aroylbenzo[b]furan derivatives as highly potent tubulin polymerization inhibitors.

Eur J Med Chem 2020 Aug 12;200:112448. Epub 2020 May 12.

Dipartimento di Salute della Donna e del Bambino, Laboratorio di Oncoematologia, Università di Padova, 35131, Padova, Italy. Electronic address:

A new class of inhibitors of tubulin polymerization based on the 2-amino-3-(3',4',5'-trimethoxybenzoyl)benzo[b]furan molecular scaffold was synthesized and evaluated for in vivo and in vitro biological activity. These derivatives were synthesized with different electron-releasing or electron-withdrawing substituents at one of the C-4 through C-7 positions. Methoxy substitution and location on the benzene part of the benzo[b]furan ring played an important role in affecting antiproliferative activity, with the greatest activity occurring with the methoxy group at the C-6 position, the least with the substituent at C-4. The same effect was also observed with ethoxy, methyl or bromine at the C-6 position of the benzo[b]furan skeleton, with the 6-ethoxy-2-amino-3-(3',4',5'-trimethoxybenzoyl)benzo[b]furan derivative 4f as the most promising compound of the series. This compound showed remarkable antiproliferative activity (IC: 5 pM) against the Daoy medulloblastoma cell line, and 4f was nearly devoid of toxicity on healthy human lymphocytes and astrocytes. The potent antiproliferative activity of 4f was derived from its inhibition of tubulin polymerization by binding to the colchicine site. The compound was also examined for in vivo activity, showing higher potency at 15 mg/kg compared with the reference compound combretastatin A-4 phosphate at 30 mg/kg against a syngeneic murine mammary tumor.
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http://dx.doi.org/10.1016/j.ejmech.2020.112448DOI Listing
August 2020

Synthesis and Biological Evaluation of 2-Substituted Benzyl-/Phenylethylamino-4-amino-5-aroylthiazoles as Apoptosis-Inducing Anticancer Agents.

Molecules 2020 May 6;25(9). Epub 2020 May 6.

Dipartimento di Scienze Chimiche e Farmaceutiche, University of Ferrara, Via L. Borsari 46, 44121 Ferrara, Italy.

Induction of apoptosis is a common chemotherapeutic mechanism to kill cancer cells The thiazole system has been reported over the past decades as a building block for the preparation of anticancer agents. A novel series of 2-arylalkylamino-4-amino-5-(3',4',5'-trimethoxybenzoyl)-thiazole derivatives designed as dual inhibitors of tubulin and cyclin-dependent kinases (CDKs) were synthesized and evaluated for their antiproliferative activity in vitro against two cancer cell lines and, for selected highly active compounds, for interactions with tubulin and cyclin-dependent kinases and for cell cycle and apoptosis effects. Structure-activity relationships were elucidated for various substituents at the 2-position of the thiazole skeleton. Among the synthesized compounds, the most active analogues were found to be the -chlorobenzylamino derivative as well as the -chloro and -methoxyphenethylamino analogues and , respectively, which inhibited the growth of U-937 and SK-MEL-1 cancer cell lines with IC values ranging from 5.7 to 12.2 μM. On U-937 cells, the tested compounds and induced apoptosis in a time and concentration dependent manner. These two latter molecules did not affect tubulin polymerization (IC > 20 μM) nor CDK activity at a single concentration of 10 μM, suggesting alternative targets than tubulin and CDK for the compounds.
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http://dx.doi.org/10.3390/molecules25092177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7248693PMC
May 2020

Synthesis and Biological Evaluation of New Antitubulin Agents Containing 2-(3',4',5'-trimethoxyanilino)-3,6-disubstituted-4,5,6,7-tetrahydrothieno[2,3-]pyridine Scaffold.

Molecules 2020 Apr 7;25(7). Epub 2020 Apr 7.

Dipartimento di Scienze della Vita e Biotecnologie, Università di Ferrara, 44121 Ferrara, Italy.

Two novel series of compounds based on the 4,5,6,7-tetrahydrothieno[2,3-]pyridine and 4,5,6,7-tetrahydrobenzo[]thiophene molecular skeleton, characterized by the presence of a 3',4',5'-trimethoxyanilino moiety and a cyano or an alkoxycarbonyl group at its 2- or 3-position, respectively, were designed, synthesized, and evaluated for antiproliferative activity on a panel of cancer cell lines and for selected highly active compounds, inhibition of tubulin polymerization, and cell cycle effects. We have identified the 2-(3',4',5'-trimethoxyanilino)-3-cyano-6-methoxycarbonyl-4,5,6,7-tetrahydrothieno[2,3-]pyridine derivative and its 6-ethoxycarbonyl homologue as new antiproliferative agents that inhibit cancer cell growth with IC values ranging from 1.1 to 4.7 μM against a panel of three cancer cell lines. Their interaction with tubulin at micromolar levels leads to the accumulation of cells in the G2/M phase of the cell cycle and to an apoptotic cell death. The cell apoptosis study found that compounds and were very effective in the induction of apoptosis in a dose-dependent manner. These two derivatives did not induce cell death in normal human peripheral blood mononuclear cells, suggesting that they may be selective against cancer cells. Molecular docking studies confirmed that the inhibitory activity of these molecules on tubulin polymerization derived from binding to the colchicine site.
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http://dx.doi.org/10.3390/molecules25071690DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181277PMC
April 2020

Synthesis and antiviral effect of novel fluoxetine analogues as enterovirus 2C inhibitors.

Antiviral Res 2020 06 29;178:104781. Epub 2020 Mar 29.

School of Pharmacy & Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff, CF10 3NB, UK. Electronic address:

Enteroviruses (EV) are a group of positive-strand RNA (+RNA) viruses that include many important human pathogens (e.g. poliovirus, coxsackievirus, echovirus, numbered enteroviruses and rhinoviruses). Fluoxetine was identified in drug repurposing screens as potent inhibitor of enterovirus B and enterovirus D replication. In this paper we are reporting the synthesis and the antiviral effect of a series of fluoxetine analogues. The results obtained offer a preliminary insight into the structure-activity relationship of its chemical scaffold and confirm the importance of the chiral configuration. We identified a racemic fluoxetine analogue, 2b, which showed a similar antiviral activity compared to (S)-fluoxetine. Investigating the stereochemistry of 2b revealed that the S-enantiomer exerts potent antiviral activity and increased the antiviral spectrum compared to the racemic mixture of 2b. In line with the observed antiviral effect, the S-enantiomer displayed a dose-dependent shift in the melting temperature in thermal shift assays, indicative for direct binding to the recombinant 2C protein.
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http://dx.doi.org/10.1016/j.antiviral.2020.104781DOI Listing
June 2020

Suramin Inhibits Chikungunya Virus Replication by Interacting with Virions and Blocking the Early Steps of Infection.

Viruses 2020 03 17;12(3). Epub 2020 Mar 17.

Department of Medical Microbiology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands.

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that can cause a debilitating disease that is primarily characterized by persistent joint pain. CHIKV has been emerging globally, while neither a vaccine nor antiviral medication is available. The anti-parasitic drug suramin was previously shown to inhibit CHIKV replication. In this study we aimed to obtain more detailed insight into its mechanism of action. We found that suramin interacts with virions and can inhibit virus binding to cells. It also appeared to inhibit post-attachment steps of the infection process, likely by preventing conformational changes of the envelope glycoproteins required for fusion and the progression of infection. Suramin-resistant CHIKV strains were selected and genotyping and reverse genetics experiments indicated that mutations in E2 were responsible for resistance. The substitutions N5R and H18Q were reverse engineered in the E2 glycoprotein in order to understand their role in resistance. The binding of suramin-resistant viruses with these two E2 mutations was inhibited by suramin like that of wild-type virus, but they appeared to be able to overcome the post-attachment inhibitory effect of suramin. Conversely, a virus with a G82R mutation in E2 (implicated in attenuation of vaccine strain 181/25), which renders it dependent on the interaction with heparan sulfate for entry, was more sensitive to suramin than wild-type virus. Using molecular modelling studies, we predicted the potential suramin binding sites on the mature spikes of the chikungunya virion. We conclude that suramin interferes with CHIKV entry by interacting with the E2 envelope protein, which inhibits attachment and also interferes with conformational changes required for fusion.
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http://dx.doi.org/10.3390/v12030314DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7150963PMC
March 2020

Rational modifications, synthesis and biological evaluation of new potential antivirals for RSV designed to target the M2-1 protein.

Bioorg Med Chem 2020 04 26;28(8):115401. Epub 2020 Feb 26.

Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff, King Edward VII Avenue, Cardiff CF103NB, UK; Department of Chemistry, Swansea University, Swansea, UK.

Respiratory syncytial virus (RSV) is the main cause of lower respiratory tract diseases in infants and young children, with potentially serious and fatal consequences associated with severe infections. Despite extensive research efforts invested in the identification of therapeutic measures, no vaccine is currently available, while treatment options are limited to ribavirin and palivizumab, which both present significant limitations. While clinical and pre-clinical candidates mainly target the viral fusion protein, the nucleocapsid protein or the viral polymerase, our focus has been the identification of new antiviral compounds targeting the viral M2-1 protein, thanks to the presence of a zinc-ejecting group in their chemical structure. Starting from an anti-RSV hit we had previously identified with an in silico structure-based approach, we have designed, synthesised and evaluated a new series of dithiocarbamate analogues, with which we have explored the antiviral activity of this scaffold. The findings presented in this work may provide the basis for the identification of a new antiviral lead to treat RSV infections.
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http://dx.doi.org/10.1016/j.bmc.2020.115401DOI Listing
April 2020

Design, synthesis and biological evaluation of 2-alkoxycarbonyl-3-anilinoindoles as a new class of potent inhibitors of tubulin polymerization.

Bioorg Chem 2020 04 18;97:103665. Epub 2020 Feb 18.

Rega Institute for Medical Research, KU Leuven, Laboratory of Virology and Chemotherapy, Leuven, Belgium.

A new class of inhibitors of tubulin polymerization based on the 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)indole molecular skeleton was synthesized and evaluated for antiproliferative activity, inhibition of tubulin polymerization and cell cycle effects. The results presented show that the methoxy substitution and location on the indole nucleus plays an important role in inhibition of cell growth, and the most favorable position for the substituent was at C-6. In addition, a small-size ester function (methoxy/ethoxycarbonyl) at the 2-position of the indole core was desirable. Also, analogues that were alkylated with methyl, ethyl or n-propyl groups or had a benzyl moiety on the N-1 indolic nitrogen retained activity equivalent to those observed in the parent N-1H analogues. The most promising compounds of the series were 2-methoxycarbonyl-3-(3',4'.5'-trimethoxyanilino)-5-methoxyindole 3f and 1-methyl-2-methoxycarbonyl-3-(3',4'.5'-trimethoxyanilino)-6-methoxy-indole 3w, both of which target tubulin at the colchicine site with antitubulin activities comparable to that of the reference compound combretastatin A-4.
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http://dx.doi.org/10.1016/j.bioorg.2020.103665DOI Listing
April 2020

A new antiviral scaffold for human norovirus identified with computer-aided approaches on the viral polymerase.

Sci Rep 2019 12 5;9(1):18413. Epub 2019 Dec 5.

Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff, King Edward VII Avenue, Cardiff, CF103NB, UK.

Human norovirus is the leading cause of acute gastroenteritis worldwide, affecting every year 685 million people. In about one third of cases, this virus affects children under five years of age, causing each year up to 200,000 child deaths, mainly in the developing countries. Norovirus outbreaks are associated with very significant economic losses, with an estimated societal cost of 60 billion dollars per year. Despite the marked socio-economic consequences associated, no therapeutic options or vaccines are currently available to treat or prevent this infection. One promising target to identify new antiviral agents for norovirus is the viral polymerase, which has a pivotal role for the viral replication and lacks closely homologous structures in the host. Starting from the scaffold of a novel class of norovirus polymerase inhibitors recently discovered in our research group with a computer-aided method, different new chemical modifications were designed and carried out, with the aim to identify improved agents effective against norovirus replication in cell-based assays. While different new inhibitors of the viral polymerase were found, a further computer-aided ligand optimisation approach led to the identification of a new antiviral scaffold for norovirus, which inhibits human norovirus replication at low-micromolar concentrations.
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http://dx.doi.org/10.1038/s41598-019-54903-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6895199PMC
December 2019

The repositioning of epigenetic probes/inhibitors identifies new anti-schistosomal lead compounds and chemotherapeutic targets.

PLoS Negl Trop Dis 2019 11 15;13(11):e0007693. Epub 2019 Nov 15.

Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Aberystwyth, United Kingdom.

Background: Praziquantel represents the frontline chemotherapy used to treat schistosomiasis, a neglected tropical disease (NTD) caused by infection with macro-parasitic blood fluke schistosomes. While this drug is safe, its inability to kill all schistosome lifecycle stages within the human host often requires repeat treatments. This limitation, amongst others, has led to the search for novel anti-schistosome replacement or combinatorial chemotherapies. Here, we describe a repositioning strategy to assess the anthelmintic activity of epigenetic probes/inhibitors obtained from the Structural Genomics Consortium.

Methodology/principle Findings: Thirty-seven epigenetic probes/inhibitors targeting histone readers, writers and erasers were initially screened against Schistosoma mansoni schistosomula using the high-throughput Roboworm platform. At 10 μM, 14 of these 37 compounds (38%) negatively affected schistosomula motility and phenotype after 72 hours of continuous co-incubation. Subsequent dose-response titrations against schistosomula and adult worms revealed epigenetic probes targeting one reader (NVS-CECR2-1), one writer (LLY-507 and BAY-598) and one eraser (GSK-J4) to be particularly active. As LLY-507/BAY-598 (SMYD2 histone methyltransferase inhibitors) and GSK-J4 (a JMJD3 histone demethylase inhibitor) regulate an epigenetic process (protein methylation) known to be critical for schistosome development, further characterisation of these compounds/putative targets was performed. RNA interference (RNAi) of one putative LLY-507/BAY-598 S. mansoni target (Smp_000700) in adult worms replicated the compound-mediated motility and egg production defects. Furthermore, H3K36me2, a known product catalysed by SMYD2 activity, was also reduced by LLY-507 (25%), BAY-598 (23%) and siSmp_000700 (15%) treatment of adult worms. Oviposition and packaging of vitelline cells into in vitro laid eggs was also significantly affected by GSK-J4 (putative cell permeable prodrug inhibitor of Smp_034000), but not by the related structural analogue GSK-J1 (cell impermeable inhibitor).

Conclusion/significance: Collectively, these results provide further support for the development of next-generation drugs targeting schistosome epigenetic pathway components. In particular, the progression of histone methylation/demethylation modulators presents a tractable strategy for anti-schistosomal control.
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http://dx.doi.org/10.1371/journal.pntd.0007693DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6881072PMC
November 2019

Design, synthesis and biological evaluation of novel vicinal diaryl-substituted 1H-Pyrazole analogues of combretastatin A-4 as highly potent tubulin polymerization inhibitors.

Eur J Med Chem 2019 Nov 1;181:111577. Epub 2019 Aug 1.

Dipartimento di Salute della Donna e del Bambino, Laboratorio di Oncoematologia, Università di Padova, 35131, Padova, Italy; Istituto di Ricerca Pediatrica (IRP), Corso Stati Uniti 4, 35128, Padova, Italy. Electronic address:

A series of 3-(3',4',5'-trimethoxyphenyl)-4-substituted 1H-pyrazole and their related 3-aryl-4-(3',4',5'-trimethoxyphenyl)-1-H-pyrazole regioisomeric derivatives, prepared as cis-rigidified combretastatin A-4 (CA-4) analogues, were synthesized and evaluated for their in vitro antiproliferative against six different cancer cell lines and, for selected highly active compounds, inhibitory effects on tubulin polymerization, cell cycle effects and in vivo potency. We retained the 3',4',5'-trimethoxyphenyl moiety as ring A throughout the present investigation, and a structure-activity relationship (SAR) information was obtained by adding electron-withdrawing (OCF, CF) or electron-releasing (alkyl and alkoxy) groups on the second aryl ring, corresponding to the B-ring of CA-4, either at the 3- or 4-position of the pyrazole nucleus. In addition, the B-ring was replaced with a benzo[b]thien-2-yl moiety. For many of the compounds, their activity was greater than, or comparable with, that of CA-4. Maximal activity was observed with the two regioisomeric derivatives characterized by the presence of a 4-ethoxyphenyl and a 3',4',5'-trimethoxyphenyl group at the C-3 and C-4 positions, and vice versa, of the 1H-pyrazole ring. The data showed that the 3',4',5'-trimethoxyphenyl moiety can be moved from the 3- to the 4-position of the 1H-pyrazole ring without significantly affecting antiproliferative activity. The most active derivatives bound to the colchicine site of tubulin and inhibited tubulin polymerization at submicromolar concentrations. In vivo experiments, on an orthotopic murine mammary tumor, revealed that 4c inhibited tumor growth even at low concentrations (5 mg/kg) compared to CA-4P (30 mg/kg).
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http://dx.doi.org/10.1016/j.ejmech.2019.111577DOI Listing
November 2019

A new series of bicalutamide, enzalutamide and enobosarm derivatives carrying pentafluorosulfanyl (SF) and pentafluoroethyl (CF) substituents: Improved antiproliferative agents against prostate cancer.

Eur J Med Chem 2019 Oct 3;180:1-14. Epub 2019 Jul 3.

School of Pharmacy and Pharmaceutical Sciences, Redwood Building, King Edwards VII Avenue, CF10 3NB, Cardiff, Wales, UK.

SAR studies on bicalutamide, enobosarm and enzalutamide analogues, functionalised with polyfluorinated groups, is presented. Among the novel bicalutamide and enobosarm derivatives synthesised, several displayed significantly improved in vitro anticancer activity, with IC values in the low micromolar range against four different prostate cancer cell lines (LNCaP, VCaP, DU-145 and 22Rv1), showing up to 48-fold increase in comparison with the parent structures. In particular, SF enobosarm analogues were found to be most potent compounds, full AR antagonists and with favourable ADME properties. The most promising compound (48a) was evaluated for its in vivo efficacy in PC xenograft mouse model (22Rv1) with results comparable to the standard-of-care docetaxel.
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http://dx.doi.org/10.1016/j.ejmech.2019.07.001DOI Listing
October 2019

A novel interaction between dengue virus nonstructural protein 1 and the NS4A-2K-4B precursor is required for viral RNA replication but not for formation of the membranous replication organelle.

PLoS Pathog 2019 05 9;15(5):e1007736. Epub 2019 May 9.

Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany.

Dengue virus (DENV) has emerged as major human pathogen. Despite the serious socio-economic impact of DENV-associated diseases, antiviral therapy is missing. DENV replicates in the cytoplasm of infected cells and induces a membranous replication organelle, formed by invaginations of the endoplasmic reticulum membrane and designated vesicle packets (VPs). Nonstructural protein 1 (NS1) of DENV is a multifunctional protein. It is secreted from cells to counteract antiviral immune responses, but also critically contributes to the severe clinical manifestations of dengue. In addition, NS1 is indispensable for viral RNA replication, but the underlying molecular mechanism remains elusive. In this study, we employed a combination of genetic, biochemical and imaging approaches to dissect the determinants in NS1 contributing to its various functions in the viral replication cycle. Several important observations were made. First, we identified a cluster of amino acid residues in the exposed region of the β-ladder domain of NS1 that are essential for NS1 secretion. Second, we revealed a novel interaction of NS1 with the NS4A-2K-4B cleavage intermediate, but not with mature NS4A or NS4B. This interaction is required for RNA replication, with two residues within the connector region of the NS1 "Wing" domain being crucial for binding of the NS4A-2K-4B precursor. By using a polyprotein expression system allowing the formation of VPs in the absence of viral RNA replication, we show that the NS1 -NS4A-2K-4B interaction is not required for VP formation, arguing that the association between these two proteins plays a more direct role in the RNA amplification process. Third, through analysis of polyproteins containing deletions in NS1, and employing a trans-complementation assay, we show that both cis and trans acting elements within NS1 contribute to VP formation, with the capability of NS1 mutants to form VPs correlating with their capability to support RNA replication. In conclusion, these results reveal a direct role of NS1 in VP formation that is independent from RNA replication, and argue for a critical function of a previously unrecognized NS4A-2K-NS4B precursor specifically interacting with NS1 and promoting viral RNA replication.
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http://dx.doi.org/10.1371/journal.ppat.1007736DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6508626PMC
May 2019

Design, Synthesis, and Biological Evaluation of 6-Substituted Thieno[3,2- d]pyrimidine Analogues as Dual Epidermal Growth Factor Receptor Kinase and Microtubule Inhibitors.

J Med Chem 2019 02 18;62(3):1274-1290. Epub 2019 Jan 18.

Dipartimento di Salute della Donna e del Bambino, Laboratorio di Oncoematologia , Università di Padova , 35131 Padova , Italy.

The clinical evidence for the success of tyrosine kinase inhibitors in combination with microtubule-targeting agents prompted us to design and develop single agents that possess both epidermal growth factor receptor (EGFR) kinase and tubulin polymerization inhibitory properties. A series of 6-aryl/heteroaryl-4-(3',4',5'-trimethoxyanilino)thieno[3,2- d]pyrimidine derivatives were discovered as novel dual tubulin polymerization and EGFR kinase inhibitors. The 4-(3',4',5'-trimethoxyanilino)-6-( p-tolyl)thieno[3,2- d]pyrimidine derivative 6g was the most potent compound of the series as an antiproliferative agent, with half-maximal inhibitory concentration (IC) values in the single- or double-digit nanomolar range. Compound 6g bound to tubulin in the colchicine site and inhibited tubulin assembly with an IC value of 0.71 μM, and 6g inhibited EGFR activity with an IC value of 30 nM. Our data suggested that the excellent in vitro and in vivo profile of 6g may be derived from its dual inhibition of tubulin polymerization and EGFR kinase.
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http://dx.doi.org/10.1021/acs.jmedchem.8b01391DOI Listing
February 2019

Combining bioinformatics, cheminformatics, functional genomics and whole organism approaches for identifying epigenetic drug targets in Schistosoma mansoni.

Int J Parasitol Drugs Drug Resist 2018 12 13;8(3):559-570. Epub 2018 Nov 13.

The Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, SY23 3DA, Wales, UK. Electronic address:

Schistosomiasis endangers the lives of greater than 200 million people every year and is predominantly controlled by a single class chemotherapy, praziquantel (PZQ). Development of PZQ replacement (to combat the threat of PZQ insensitivity/resistance arising) or combinatorial (to facilitate the killing of PZQ-insensitive juvenile schistosomes) chemotherapies would help sustain this control strategy into the future. Here, we re-categorise two families of druggable epigenetic targets in Schistosoma mansoni, the histone methyltransferases (HMTs) and the histone demethylases (HDMs). Amongst these, a S. mansoni Lysine Specific Demethylase 1 (SmLSD1, Smp_150560) homolog was selected for further analyses. Homology modelling of SmLSD1 and in silico docking of greater than four thousand putative inhibitors identified seven (L1 - L7) showing more favourable binding to the target pocket of SmLSD1 vs Homo sapiens HsLSD1; six of these seven (L1 - L6) plus three structural analogues of L7 (L8 - L10) were subsequently screened against schistosomula using the Roboworm anthelmintic discovery platform. The most active compounds (L10 - pirarubicin > L8 - danunorubicin hydrochloride) were subsequently tested against juvenile (3 wk old) and mature (7 wk old) schistosome stages and found to impede motility, suppress egg production and affect tegumental surfaces. When compared to a surrogate human cell line (HepG2), a moderate window of selectivity was observed for the most active compound L10 (selectivity indices - 11 for schistosomula, 9 for juveniles, 1.5 for adults). Finally, RNA interference of SmLSD1 recapitulated the egg-laying defect of schistosomes co-cultivated in the presence of L10 and L8. These preliminary results suggest that SmLSD1 represents an attractive new target for schistosomiasis; identification of more potent and selective SmLSD1 compounds, however, is essential. Nevertheless, the approaches described herein highlight an interdisciplinary strategy for selecting and screening novel/repositioned anti-schistosomals, which can be applied to any druggable (epigenetic) target encoded by the parasite's genome.
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http://dx.doi.org/10.1016/j.ijpddr.2018.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288008PMC
December 2018

3-Aryl/Heteroaryl-5-amino-1-(3',4',5'-trimethoxybenzoyl)-1,2,4-triazoles as antimicrotubule agents. Design, synthesis, antiproliferative activity and inhibition of tubulin polymerization.

Bioorg Chem 2018 10 30;80:361-374. Epub 2018 Jun 30.

Dipartimento di Salute della Donna e del Bambino, Laboratorio di Oncoematologia, Università di Padova, 35131 Padova, Italy. Electronic address:

Many natural and synthetic substances are known to interfere with the dynamic assembly of tubulin, preventing the formation of microtubules. In our search for potent and selective antitumor agents, a novel series of 1-(3',4',5'-trimethoxybenzoyl)-5-amino-1,2,4-triazoles were synthesized. The compounds had different heterocycles, including thiophene, furan or the three isomeric pyridines, and they possessed a phenyl ring bearing electron-releasing or electron-withdrawing substituents at the 3-position of the 5-amino-1,2,4-triazole system. Most of the twenty-two tested compounds showed moderate to potent antiproliferative activities against a panel of solid tumor and leukemic cell lines, with four (5j, 5k, 5o and 5p) showing strong antiproliferative activity (IC < 1 μM) against selected cancer cells. Among them, several molecules preferentially inhibited the proliferation of leukemic cell lines, showing IC values 2-100-fold lower for Jurkat and RS4;11 cells than those for the three lines derived from solid tumors (HeLa, HT-29 and MCF-7 cells). Compound 5k strongly inhibited tubulin assembly, with an IC value of 0.66 μM, half that obtained in simultaneous experiments with CA-4 (IC = 1.3 μM).
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http://dx.doi.org/10.1016/j.bioorg.2018.06.037DOI Listing
October 2018

Structure-activity relationship study of itraconazole, a broad-range inhibitor of picornavirus replication that targets oxysterol-binding protein (OSBP).

Antiviral Res 2018 08 26;156:55-63. Epub 2018 May 26.

Virology Division, Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584CL Utrecht, the Netherlands. Electronic address:

Itraconazole (ITZ) is a well-known, FDA-approved antifungal drug that is also in clinical trials for its anticancer activity. ITZ exerts its anticancer activity through several disparate targets and pathways. ITZ inhibits angiogenesis by hampering the functioning of the vascular endothelial growth receptor 2 (VEGFR2) and by indirectly inhibiting mTOR signaling. Furthermore, ITZ directly inhibits the growth of several types of tumor cells by antagonizing Hedgehog signaling. Recently, we reported that ITZ also has broad-spectrum antiviral activity against enteroviruses, cardioviruses and hepatitis C virus, independent of established ITZ-activities but instead via a novel target, oxysterol-binding protein (OSBP), a cellular lipid shuttling protein. In this study, we analyzed which structural features of ITZ are important for the OSBP-mediated antiviral activity. The backbone structure, consisting of five rings, and the sec-butyl chain are important for antiviral activity, whereas the triazole moiety, which is critical for antifungal activity, is not. The features required for OSBP-mediated antiviral activity of ITZ overlap mostly with published features required for inhibition of VEGFR2 trafficking, but not Hh signaling. Furthermore, we use in silico studies to explore how ITZ could bind to OSBP. Our data show that several pharmacological activities of ITZ can be uncoupled, which is a critical step in the development of ITZ-based antiviral compounds with greater specificity and reduced off-target effects.
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http://dx.doi.org/10.1016/j.antiviral.2018.05.010DOI Listing
August 2018

In silico screening for human norovirus antivirals reveals a novel non-nucleoside inhibitor of the viral polymerase.

Sci Rep 2018 03 7;8(1):4129. Epub 2018 Mar 7.

School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom.

Human norovirus causes approximately 219,000 deaths annually, yet there are currently no antivirals available. A virtual screening of commercially available drug-like compounds (~300,000) was performed on the suramin and PPNDS binding-sites of the norovirus RNA-dependent RNA polymerase (RdRp). Selected compounds (n = 62) were examined for inhibition of norovirus RdRp activity using an in vitro transcription assay. Eight candidates demonstrated RdRp inhibition (>25% inhibition at 10 µM), which was confirmed using a gel-shift RdRp assay for two of them. The two molecules were identified as initial hits and selected for structure-activity relationship studies, which resulted in the synthesis of novel compounds that were examined for inhibitory activity. Five compounds inhibited human norovirus RdRp activity (>50% at 10 µM), with the best candidate, 54, demonstrating an IC of 5.6 µM against the RdRp and a CC of 62.8 µM. Combinational treatment of 54 and the known RdRp site-B inhibitor PPNDS revealed antagonism, indicating that 54 binds in the same binding pocket. Two RdRps with mutations (Q414A and R419A) previously shown to be critical for the binding of site-B compounds had no effect on inhibition, suggesting 54 interacts with distinct site-B residues. This study revealed the novel scaffold 54 for further development as a norovirus antiviral.
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http://dx.doi.org/10.1038/s41598-018-22303-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5841303PMC
March 2018

Synthesis and biological evaluation of 6-substituted-5-fluorouridine ProTides.

Bioorg Med Chem 2018 02 2;26(3):551-565. Epub 2017 Dec 2.

School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, King Edward VII Avenue, Cardiff CF10 3NB, UK.

A new family of thirteen phosphoramidate prodrugs (ProTides) of different 6-substituted-5-fluorouridine nucleoside analogues were synthesized and evaluated as potential anticancer agents. In addition, antiviral activity against Chikungunya (CHIKV) virus was evaluated using a cytopathic effect inhibition assay. Although a carboxypeptidase Y assay supported a putative mechanism of activation of ProTides built on 5-fluorouridine with such C6-modifications, the Hint docking studies revealed a compromised substrate-activity for the Hint phosphoramidase-type enzyme that is likely responsible for phosphoramidate bioactivation through P-N bond cleavage and free nucleoside 5'-monophosphate delivery. Our observations may support and explain to some extent the poor in vitro biological activity generally demonstrated by the series of 6-substituted-5-fluorouridine phosphoramidates (ProTides) and will be of guidance for the design of novel phosphoramidate prodrugs.
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http://dx.doi.org/10.1016/j.bmc.2017.11.037DOI Listing
February 2018

2-Alkoxycarbonyl-3-arylamino-5-substituted thiophenes as a novel class of antimicrotubule agents: Design, synthesis, cell growth and tubulin polymerization inhibition.

Eur J Med Chem 2018 Jan;143:683-698

Dipartimento di Salute della Donna e del Bambino, Laboratorio di Oncoematologia Pediatrica, Università di Padova, 35131 Padova, Italy. Electronic address:

Microtubules are recognized as crucial components of the mitotic spindle during cell division, and, for this reason, the microtubule system is an attractive target for the development of anticancer agents. Continuing our search strategy for novel tubulin targeting-compounds, a new series of 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)-5-aryl/heteroarylthiophene derivatives was designed, synthesized and demonstrated to act as tubulin polymerization inhibitors at the colchicine site. A structure-activity relationship study on the phenyl at the 5-position of the thiophene ring was performed by introducing a variety of substituents containing electron-releasing and electron-withdrawing groups, with the 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)thiophene scaffold being the minimum structural requirement for activity. Of the tested compounds, derivatives 4a, 4c, 4i and 4k possessed the highest overall potency and displayed high antiproliferative activities at submicromolar concentrations, with IC values ranging from 0.13 to 0.84 μM against four different cancer cell lines. Three agents (4a, 4c and 4i) in the present series had similar effects, and these were comparable to those of the reference compound combretastatin A-4 (CA-4) as inhibitors of tubulin assembly. The antitubulin effects correlated with the cytostatic activities and indicate that these compounds inhibit cell growth through inhibition of tubulin polymerization by binding at the colchicine site. Compound 4c, containing the 2'-thienyl ring at the 5-position of the 2-methoxycarbonyl-3-(3',4',5'-trimethoxyanilino)thiophene scaffold, exhibited substantial antiproliferative activity with a mean IC value of 140 nM, inhibited tubulin polymerization with an IC value of 1.2 μM, similar to that of CA-4 (IC: 1.1 μM), and induced apoptosis in HeLa cells.
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http://dx.doi.org/10.1016/j.ejmech.2017.11.096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5791907PMC
January 2018

Networks of enzymatically oxidized membrane lipids support calcium-dependent coagulation factor binding to maintain hemostasis.

Sci Signal 2017 Nov 28;10(507). Epub 2017 Nov 28.

Systems Immunity Research Institute, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.

Blood coagulation functions as part of the innate immune system by preventing bacterial invasion, and it is critical to stopping blood loss (hemostasis). Coagulation involves the external membrane surface of activated platelets and leukocytes. Using lipidomic, genetic, biochemical, and mathematical modeling approaches, we found that enzymatically oxidized phospholipids (eoxPLs) generated by the activity of leukocyte or platelet lipoxygenases (LOXs) were required for normal hemostasis and promoted coagulation factor activities in a Ca- and phosphatidylserine (PS)-dependent manner. In wild-type mice, hydroxyeicosatetraenoic acid-phospholipids (HETE-PLs) enhanced coagulation and restored normal hemostasis in clotting-deficient animals genetically lacking p12-LOX or 12/15-LOX activity. Murine platelets generated 22 eoxPL species, all of which were missing in the absence of p12-LOX. Humans with the thrombotic disorder antiphospholipid syndrome (APS) had statistically significantly increased HETE-PLs in platelets and leukocytes, as well as greater HETE-PL immunoreactivity, than healthy controls. HETE-PLs enhanced membrane binding of the serum protein β2GP1 (β2-glycoprotein 1), an event considered central to the autoimmune reactivity responsible for APS symptoms. Correlation network analysis of 47 platelet eoxPL species in platelets from APS and control subjects identified their enzymatic origin and revealed a complex network of regulation, with the abundance of 31 p12-LOX-derived eoxPL molecules substantially increased in APS. In summary, circulating blood cells generate networks of eoxPL molecules, including HETE-PLs, which change membrane properties to enhance blood coagulation and contribute to the excessive clotting and immunoreactivity of patients with APS.
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http://dx.doi.org/10.1126/scisignal.aan2787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5720345PMC
November 2017

Broad-spectrum non-nucleoside inhibitors for caliciviruses.

Antiviral Res 2017 Oct 27;146:65-75. Epub 2017 Jul 27.

School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia. Electronic address:

Viruses of the Caliciviridae cause significant and sometimes lethal diseases, however despite substantial research efforts, specific antivirals are lacking. Broad-spectrum antivirals could combat multiple viral pathogens, offering a rapid solution when no therapies exist. The RNA-dependent RNA polymerase (RdRp) is an attractive antiviral target as it is essential for viral replication and lacks mammalian homologs. To focus the search for pan-Caliciviridae antivirals, the RdRp was probed with non-nucleoside inhibitors (NNIs) developed against hepatitis C virus (HCV) to reveal both allosteric ligands for structure-activity relationship enhancement, and highly-conserved RdRp pockets for antiviral targeting. The ability of HCV NNIs to inhibit calicivirus RdRp activities was assessed using in vitro enzyme and murine norovirus cell culture assays. Results revealed that three NNIs which bound the HCV RdRp Thumb I (TI) site also inhibited transcriptional activities of six RdRps spanning the Norovirus, Sapovirus and Lagovirus genera of the Caliciviridae. These NNIs included JTK-109 (RdRp inhibition range: IC 4.3-16.6 μM), TMC-647055 (IC range: 18.8-45.4 μM) and Beclabuvir (IC range: 23.8->100 μM). In silico studies and site-directed mutagenesis indicated the JTK-109 binding site was within the calicivirus RdRp thumb domain, in a pocket termed Site-B, which is highly-conserved within all calicivirus RdRps. Additionally, RdRp inhibition assays revealed that JTK-109 was antagonistic with the previously reported RdRp inhibitor pyridoxal-5'-phosphate-6-(2'-naphthylazo-6'-nitro-4',8'-disulfonate) tetrasodium salt (PPNDS), that also binds to Site-B. Moreover, like JTK-109, PPNDS was also a potent inhibitor of polymerases from six viruses spanning the three Caliciviridae genera tested (IC range: 0.1-2.3 μM). Together, this study demonstrates the potential for de novo development of broad-spectrum antivirals that target the highly-conserved RdRp thumb pocket, Site-B. We also revealed three broad-spectrum HCV NNIs that could be used as antiviral scaffolds for further development against caliciviruses and other viruses.
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http://dx.doi.org/10.1016/j.antiviral.2017.07.014DOI Listing
October 2017

Rational design and synthesis of novel phenylsulfonyl-benzamides as anti-prostate cancer agents.

Medchemcomm 2017 Jul 26;8(7):1414-1420. Epub 2017 May 26.

School of Pharmacy and Pharmaceutical Sciences , Redwood Building, King Edward VII Avenue , CF10 3NB , Cardiff , Wales , UK . Email:

Prostate cancer is a major cause of male death worldwide and the identification of new efficient treatments is constantly needed. Different non-steroidal androgen receptor antagonists are approved also in the case of castration-resistant cancer forms. Using a rational approach and molecular modelling studies to modify the structure of antiandrogen drug bicalutamide, a new series of phenylsulfonyl-benzamide derivatives was designed and synthesised. Their antiproliferative activities were evaluated in four different human prostate cancer cell lines and several new compounds showed significantly improved IC values in the low μM range. The cytotoxicity profile was also evaluated for the novel structures in the HEK293 cell line.
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http://dx.doi.org/10.1039/c7md00164aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6072516PMC
July 2017

Synthesis and Biological Evaluation of 2-Methyl-4,5-Disubstituted Oxazoles as a Novel Class of Highly Potent Antitubulin Agents.

Sci Rep 2017 04 13;7:46356. Epub 2017 Apr 13.

Dipartimento di Salute della Donna e del Bambino, Laboratorio di Oncoematologia, Università di Padova, 35131 Padova, Italy.

Antimitotic agents that interfere with microtubule formation are one of the major classes of cytotoxic drugs for cancer treatment. Multiple 2-methyl-4-(3',4',5'-trimethoxyphenyl)-5-substituted oxazoles and their related 4-substituted-5-(3',4',5'-trimethoxyphenyl) regioisomeric derivatives designed as cis-constrained combretastatin A-4 (CA-4) analogues were synthesized and evaluated for their antiproliferative activity in vitro against a panel of cancer cell lines and, for selected highly active compounds, interaction with tubulin, cell cycle effects and in vivo potency. Both these series of compounds were characterized by the presence of a common 3',4',5'-trimethoxyphenyl ring at either the C-4 or C-5 position of the 2-methyloxazole ring. Compounds 4g and 4i, bearing a m-fluoro-p-methoxyphenyl or p-ethoxyphenyl moiety at the 5-position of 2-methyloxazole nucleus, respectively, exhibited the greatest antiproliferative activity, with IC values of 0.35-4.6 nM (4g) and 0.5-20.2 nM (4i), which are similar to those obtained with CA-4. These compounds bound to the colchicine site of tubulin and inhibited tubulin polymerization at submicromolar concentrations. Furthermore, 4i strongly induced apoptosis that follows the mitochondrial pathway. In vivo, 4i in a mouse syngeneic model demonstrated high antitumor activity which significantly reduced the tumor mass at doses ten times lower than that required for CA-4P, suggesting that 4i warrants further evaluation as a potential anticancer drug.
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http://dx.doi.org/10.1038/srep46356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5390315PMC
April 2017

Therapeutically targeting guanylate cyclase-C: computational modeling of plecanatide, a uroguanylin analog.

Pharmacol Res Perspect 2017 Apr 12;5(2):e00295. Epub 2017 Mar 12.

Synergy Pharmaceuticals New York New York.

Plecanatide is a recently developed guanylate cyclase-C (GC-C) agonist and the first uroguanylin analog designed to treat chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation (IBS-C). GC-C receptors are found across the length of the intestines and are thought to play a key role in fluid regulation and electrolyte balance. Ligands of the GC-C receptor include endogenous agonists, uroguanylin and guanylin, as well as diarrheagenic, Escherichia coli heat-stable enterotoxins (ST). Plecanatide mimics uroguanylin in its 2 disulfide-bond structure and in its ability to activate GC-Cs in a pH-dependent manner, a feature associated with the presence of acid-sensing residues (Asp2 and Glu3). Linaclotide, a synthetic analog of STh (a 19 amino acid member of ST family), contains the enterotoxin's key structural elements, including the presence of three disulfide bonds. Linaclotide, like STh, activates GC-Cs in a pH-independent manner due to the absence of pH-sensing residues. In this study, molecular dynamics simulations compared the stability of plecanatide and linaclotide to STh. Three-dimensional structures of plecanatide at various protonation states (pH 2.0, 5.0, and 7.0) were simulated with GROMACS software. Deviations from ideal binding conformations were quantified using root mean square deviation values. Simulations of linaclotide revealed a rigid conformer most similar to STh. Plecanatide simulations retained the flexible, pH-dependent structure of uroguanylin. The most active conformers of plecanatide were found at pH 5.0, which is the pH found in the proximal small intestine. GC-C receptor activation in this region would stimulate intraluminal fluid secretion, potentially relieving symptoms associated with CIC and IBS-C.
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http://dx.doi.org/10.1002/prp2.295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5368960PMC
April 2017