Lieve Naesens

Cardiff University, Cardiff, WLS, United Kingdom

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Publications (196)707.1 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Hypoxanthine-guanine-[xanthine] phosphoribosyltransferase (HG[X]PRT) is considered an important target for anti-malarial chemotherapy as it is the only pathway for the synthesis of the purine nucleoside monophosphates required for DNA/RNA production. Thus, inhibition of this enzyme should result in cessation of replication. The aza-acyclic nucleoside phosphonates (aza-ANPs) are good inhibitors of Plasmodium falciparum HGXPRT (Pf HGXPRT) with Ki values as low as 0.08 μM and 0.01 μM for Plasmodium vivax HGPRT (PvHGPRT). Prodrugs of these aza-ANPs exhibit anti-malarial activity against Pf lines with IC 50 values (0.8-2.7 μM) and have low cytotoxicity against human cells. Crystal structures of six of these compounds in complex with human HGPRT have been determined. These suggest that the different affinities of these aza-ANPs could be due to the flexibility of the loops surrounding the active site as well as the flexibility of the inhibitors allowing them to adapt to fit into three binding pockets of the enzyme(s).
    Journal of Medicinal Chemistry 12/2014; · 5.48 Impact Factor
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    ABSTRACT: The influenza virus PA endonuclease, which cleaves capped cellular pre-mRNAs to prime viral mRNA synthesis, is a promising target for novel anti-influenza virus therapeutics. The catalytic center of this enzyme resides in the N-terminal part of PA (PA-Nter) and contains two (or possibly one or three) Mg(2+) or Mn(2+) ions which are critical for its catalytic function. There is large interest in PA inhibitors that are optimally designed to occupy the active site and chelate the metal ions. We here focused on a series of β-diketo acid (DKA) and DKA-bioisosteric compounds containing different scaffolds, and determined their structure-activity relationship in an enzymatic assay with PA-Nter, to build a 3D pharmacophore model. Besides, we developed a molecular beacon (MB)-based PA-Nter assay which enables to compare the inhibition versus Mn(2+) or Mg(2+), the latter probably being the biologically relevant cofactor. This real-time MB assay allows to measure the enzyme kinetics of PA-Nter or perform high-throughput screening. Several DKA derivatives were found to cause strong inhibition of PA-Nter with IC50 values comparable to that of the prototype L-742,001 (i.e. below 2 μM). Among the different compounds tested, L-742,001 appeared unique in having equal activity against either Mg(2+) or Mn(2+). Three compounds ( 10: , with a pyrrole scaffold, and 40: and 41: , with an indole scaffold) exhibited moderate antiviral activity in cell culture (EC99 values: 64-95 μM), and were proven to affect viral RNA synthesis. Our approach to integrate complementary enzymatic, cellular and mechanistic assays should guide ongoing development of improved influenza virus PA inhibitors. The American Society for Pharmacology and Experimental Therapeutics.
    Molecular pharmacology 12/2014; · 4.12 Impact Factor
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    ABSTRACT: We report on the synthesis of novel conformationally locked nucleoside and nucleotide derivatives, which are structurally closely related to clinically used antivirals such as didanosine and abacavir. As a suitable conformationally rigid substitute of the sugar/pseudosugar ring allowing a permanent stabilization of the nucleoside in North conformation we employed bicyclo[2.2.1]heptane (norbornane) substituted in the bridgehead position with a hydroxymethyl group and in the C-3 position with a nucleobase. Prepared nucleoside derivatives were also converted into appropriate phosphoramidate prodrugs (ProTides) in order to increase delivery of the compounds in the cells. All target compounds were evaluated in a broad antiviral and cytostatic assay panel.
    Bioorganic & Medicinal Chemistry 11/2014; · 2.95 Impact Factor
  • 2nd Innovative Approaches for Identification of Antiviral Agents Summer School, Cagliari, Sardinia, Italy,; 10/2014
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    Bioorganic & Medicinal Chemistry Letters. 08/2014; 24(15):3251–3254.
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    ABSTRACT: Data regarding the activity of metal complexes against HIV virus in cell are surprisingly scarce. In this study, we present the antiviral activity against HIV-infected cells of different types of chelating ligands and of their metal complexes. In particular, the carboxamide chelating scaffold and the corresponding coordination compounds demonstrated an interesting antiviral profile in the nanomolar range. These molecules inhibit not only HIV integrase catalytic activity, but they also interfere with the function of the RNase H component of the HIV reverse transcriptase. Here we also discuss the thermodynamic characterization in solution of the metal complexes of the most active ligands, affording to the best of our knowledge for the first time this type of data for complexes with anti-HIV activity.
    European Journal of Medicinal Chemistry 06/2014; 83C:594-600. · 3.43 Impact Factor
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    ABSTRACT: Amantadine inhibits the M2 proton channel of influenza A virus, yet most of the currently circulating strains of the virus carry mutations in the M2 protein that render the virus amantadine-resistant. While most of the research on novel amantadine analogs has revolved around the synthesis of novel adamantane derivatives, we have recently found that other polycyclic scaffolds effectively block the M2 proton channel, including amantadine-resistant mutant channels. In this paper, we have synthesized and characterized a series of pyrrolidine derivatives designed as analogs of amantadine. Inhibition of the wild-type M2 channel and the A/M2-S31N, A/M2-V27A and A/M2-L26F mutant forms of the channel were measured in Xenopus oocytes using two-electrode voltage clamp assays. Most of the novel compounds inhibited the wild type ion channel in the low micromolar range. Of note, two of the compounds inhibited the amantadine-resistant A/M2-V27A and A/M2-L26F mutant ion channels with submicromolar and low micromolar IC50, respectively. None of the compounds was found to inhibit the S31N mutant ion channel.
    Journal of Medicinal Chemistry 06/2014; · 5.48 Impact Factor
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    ABSTRACT: In order to obtain new, cluster-forming antibiotic compounds, teicoplanin pseudoaglycone derivatives containing two lipophilic n-octyl chains have been synthesized. The compounds proved to be poor antibacterials, but, surprisingly, they exhibited potent anti-influenza virus activity against influenza A strains. This antiviral action was related to inhibition of the binding interaction between the virus and the host cell. Related analogs bearing methyl substituents in lieu of the octyl chains, displayed no anti-influenza virus activity. Hence, an interaction between the active, dually n-octylated compounds and the lipid bilayer of the host cell can be postulated, to explain the observed inhibition of influenza virus attachment.
    Bioorganic & Medicinal Chemistry Letters 06/2014; · 2.33 Impact Factor
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    ABSTRACT: The synthesis of several [4,4,3], [4,3,3], and [3,3,3]azapropellanes is reported. Several of the novel amines displayed low-micromolar activities against an amantadine-resistant H1N1 strain, but they did not show activity against an amantadine-sensitive H3N2 strain. None of the tested compounds inhibit the influenza A/M2 proton channel function. Most of the compounds did not show cytotoxicity for MDCK cells.
    ACS Medicinal Chemistry Letters 05/2014; · 3.07 Impact Factor
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    ABSTRACT: In order to obtain self assembling, multivalent ligand for influenza virus hemagglutinin α-N-acetylneuraminyl-(2-6)-d-galactopyranose has been synthesized and bonded to a water soluble fullerene derivative using 1,3-dipolar cycloaddition click reaction. The aggregating amphiphilic compound did not inhibit the influenza virus hemagglutinin, but it proved to be an inhibitor of its neuraminidase with a 50% inhibitory concentration of 81μM.
    Bioorganic & medicinal chemistry letters 04/2014; · 2.65 Impact Factor
  • European Journal of Medicinal Chemistry. 01/2014; 83:594–600.
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    ABSTRACT: We have synthesized and characterized a series of compounds containing the 3-azatetracyclo[,8).0(1,5)]undecane scaffold designed as analogues of amantadine, an inhibitor of the M2 proton channel of influenza A virus. Inhibition of the wild-type (WT) M2 channel and the amantadine-resistant A/M2-S31N and A/M2-V27A mutant ion channels were measured in Xenopus oocytes using two-electrode voltage clamp (TEV) assays. Most of the novel compounds inhibited the WT ion channel in the low micromolar range. Of note, several compounds inhibited the A/M2 V27A mutant ion channel, one of them with submicromolar IC50. None of the compounds was found to inhibit the S31N mutant ion channel. The antiviral activity of three novel dual WT and A/M2-V27A channels inhibitors was confirmed by influenza virus yield assays.
    Journal of Medicinal Chemistry 11/2013; · 5.48 Impact Factor
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    ABSTRACT: The influenza virus PA endonuclease is an attractive target for development of novel anti-influenza virus therapeutics. Reported PA inhibitors chelate the divalent metal ion(s) in the enzyme's catalytic site, which is located in the N-terminal part of PA (PA-Nter). In this work, a series of 2-hydroxybenzamide-based compounds have been synthesized and biologically evaluated in order to identify the essential pharmacophoric motif, which could be involved in functional sequestration of the metal ions (probably Mg2+) in the catalytic site of PA. By using HL1, H2L2, and HL3 as model ligands with Mg2+ ions, we isolated and fully characterized a series of complexes and tested them for inhibitory activity towards PA-Nter endonuclease. H2L2 and the corresponding Mg2+ complex showed an interesting inhibition of the endonuclease activity. The crystal structures of the uncomplexed HL1 and H2L2, and of the isolated magnesium complex [Mg(L3)2(MeOH)2].2MeOH were solved by X-ray diffraction analysis. Furthermore, the speciation models for HL1, H2L2, and HL3 with Mg2+ were obtained and the formation constants of the complexes were measured. Preliminary docking calculations were conducted to investigate the interactions of the title compounds with essential amino acids in the PA-Nter active site. These findings supported the "two-metal" coordination of divalent ions by a donor triad atoms chemotype as a powerful strategy to develop more potent PA endonuclease inhibitors.
    Molecular Pharmaceutics 11/2013; · 4.57 Impact Factor
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    ABSTRACT: Acyclic nucleoside phosphonates (ANPs), such as HPMPC, are an important group of broad-spectrum antiviral agents with activity against DNA viruses. In this report, we present the in vitro potency of novel ANPs against γ-herpesviruses, including Kaposi's sarcoma-associated herpesvirus, Epstein-Barr virus (EBV), and three animal γ-herpesviruses. HPMP-5-azaC, 3-deaza-HPMPA and their cyclic derivatives emerged as highly potent anti-γ-herpesvirus agents. Interestingly, cyclic prodrugs of ANPs exhibited reduced activities against EBV P3HR-1 strain, but not against EBV Akata strain. Cell culture metabolism studies with HPMPC and cyclic HPMPC revealed that these differences were attributed to an altered drug metabolism in P3HR-1 cells after EBV reactivation and more specifically to a reduced hydrolysis of cyclic HPMPC by cyclic CMP phosphodiesterase. We did not correlate this effect to phosphodiesterase downregulation, nor to functional mutations. Instead, altered cAMP levels in P3HR-1 cells indicated a competitive inhibition of the phosphodiesterase by this cyclic nucleotide. Finally, both HPMPC and HPMP-5-azaC emerged as highly effective inhibitors in vivo through significant inhibition of murine γ-herpesvirus replication and dissemination. In the current need of potent anti-γ-herpesvirus antivirals, our findings underlined the requirement of appropriate surrogate viruses for antiviral susceptibility testing and highlighted HPMP-5-azaC as a promising compound for future clinical development.
    Journal of Virology 09/2013; · 4.65 Impact Factor
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    ABSTRACT: Escherichia coli (Ec) cells possess two purine salvage enzymes: xanthine-guanine phosphoribosyltransferase (XGPRT) and hypoxanthine phosphoribosyltransferase (HPRT). EcXGPRT shares a common structural feature with other members of this family, a flexible loop that closes over the active site during catalysis. The replacement of six of these amino acids by alanine has no effect on the Km for the two substrates. However, the Ki for the nucleoside monophosphate increases by 27-fold and the kcat is reduced by ~200-fold. Nucleoside phosphonates (NP) are good inhibitors of EcXGPRT and EcHPRT with Ki values as low as 10 nM. In the absence of the flexible loop, these values increase by 5 to 30-fold indicating the importance of the loop for high affinity inhibition. Crystal structures of two NPs in complex with EcXGPRT explain the tight binding. Prodrugs of NPs with low Ki values for EcXGPRT or EcHPRT exhibit IC50 values between 5-23 µM against Mycobacterium tuberculosis in cell-based assays, suggesting that these compounds are therapeutic leads against pathogenic bacteria.
    Journal of Medicinal Chemistry 08/2013; · 5.48 Impact Factor
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    ABSTRACT: 6-Fluoro-3-hydroxy-2-pyrazinecarboxamide (T-705) is a novel antiviral compound with broad activity against influenza virus and diverse RNA viruses. Its active metabolite, T-705-ribose-5'-triphosphate (T-705-RTP), is recognized by influenza virus RNA polymerase as a substrate competing with GTP, giving inhibition of viral RNA synthesis and lethal virus mutagenesis. Which enzymes perform the activation of T-705 is unknown. We here demonstrate that human hypoxanthine guanine phosphoribosyltransferase (HGPRT) converts T-705 into its ribose-5'-monophosphate (RMP) prior to formation of T-705-RTP. The anti-influenza virus activity of T-705 and T-1105 (3-hydroxy-2-pyrazinamide; the analogue lacking the 6-fluoro atom) was lost in HGPRT-deficient MDCK cells. This HGPRT dependency was confirmed in human HEK293T cells undergoing HGPRT-specific gene knockdown followed by influenza virus ribonucleoprotein reconstitution. Knockdown for adenine phosphoribosyltransferase (APRT) or nicotinamide phosphoribosyltransferase did not change the antiviral activity of T-705 and T-1105. Enzymatic assays showed that T-705 and T-1105 are poor substrates for human HGPRT having K m(app) values of 6.4 and 4.1 mM, respectively. Formation of the RMP metabolites by APRT was negligible, and so was the formation of the ribosylated metabolites by human purine nucleoside phosphorylase. Phosphoribosylation and antiviral activity of the 2-pyrazinecarboxamide derivatives was shown to require the presence of the 3-hydroxyl but not the 6-fluoro substituent. The crystal structure of T-705-RMP in complex with human HGPRT showed how this compound binds in the active site. Since conversion of T-705 by HGPRT appears to be inefficient, T-705-RMP prodrugs may be designed to increase the antiviral potency of this new antiviral agent.
    Molecular pharmacology 08/2013; · 4.12 Impact Factor
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    ABSTRACT: The influenza virus PA endonuclease, which cleaves capped host pre-mRNAs to initiate synthesis of viral mRNA, is a prime target for antiviral therapy. The diketo acid compound L-742,001 was previously identified as a potent inhibitor of the influenza virus endonuclease reaction, but information on its precise binding mode to PA or potential resistance profile is limited. Computer-assisted docking of L-742,001 into the crystal structure of inhibitor-free N-terminal PA (PA-Nter) indicated a binding orientation distinct from that seen in a recent crystallographic study with L-742,001-bound PA-Nter. A comprehensive mutational analysis was performed to determine which amino acid changes within the catalytic center of PA or its surrounding hydrophobic pockets, alter the antiviral sensitivity to L-742,001 in cell culture. Marked (up to 20-fold) resistance to L-742,001 was observed for the H41A, I120T and G81F/V/T mutant forms of PA. Two- to threefold resistance was seen for the T20A, L42T and V122T mutants, and the R124Q and Y130A mutants were threefold more sensitive to L-742,001. Several mutations situated at non-catalytic sites in PA had no or only marginal impact on the enzymatic functionality of viral ribonucleoprotein complexes reconstituted in cell culture, consistent with the less conserved nature of these PA residues. Our data provide relevant insight into the binding mode of L-742,001 in the PA endonuclease active site. In addition, we predict some potential resistance sites to be taken into account during optimization of PA endonuclease inhibitors towards tight binding in any of the hydrophobic pockets surrounding the catalytic center of the enzyme.
    Journal of Virology 07/2013; · 4.65 Impact Factor
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    Evelien Vanderlinden, Lieve Naesens
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    ABSTRACT: Influenza A and B viruses are highly contagious respiratory pathogens with a considerable medical and socioeconomical burden and known pandemic potential. Current influenza vaccines require annual updating and provide only partial protection in some risk groups. Due to the global spread of viruses with resistance to the M2 proton channel inhibitor amantadine or the neuraminidase inhibitor oseltamivir, novel antiviral agents with an original mode of action are urgently needed. We here focus on emerging options to interfere with the influenza virus entry process, which consists of the following steps: attachment of the viral hemagglutinin to the sialylated host cell receptors, endocytosis, M2-mediated uncoating, low pH-induced membrane fusion, and, finally, import of the viral ribonucleoprotein into the nucleus. We review the current functional and structural insights in the viral and cellular components of this entry process, and the diverse antiviral strategies that are being explored. This encompasses small molecule inhibitors as well as macromolecules such as therapeutic antibodies. There is optimism that at least some of these innovative concepts to block influenza virus entry will proceed from the proof of concept to a more advanced stage. Special attention is therefore given to the challenging issues of influenza virus (sub)type-dependent activity or potential drug resistance.
    Medicinal Research Reviews 06/2013; · 8.13 Impact Factor
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    ABSTRACT: We here report on the synthesis of new series of polycyclic amines initially designed as ring-rearranged analogs of amantadine and featuring pentacyclo, hexacyclo, and octacyclo rings. A secondary amine, 3-azahexacyclo[,5).0(5,12).0(6,10).0(11,15)]pentadeca-7,13-diene, 3, effectively inhibited A/M2 proton channel function, and, moreover, possessed dual activity against an A/H3N2 virus carrying a wild-type A/M2 proton channel, as well as an amantadine-resistant A/H1N1 virus. Among the polycyclic amines that did not inhibit influenza A/M2 proton channel function, several showed low-micromolar activity against tested A/H1N1 strains (in particular, the A/PR/8/34 strain), but not A/H3N2 influenza viruses. A/PR/8/34 mutants selected for resistance to these compounds possessed mutations in the viral hemagglutinin that markedly increased the hemolysis pH. Our data suggest that A/H1N1 viruses such as the A/PR/8/34 strain are particularly sensitive to a subtle increase in the endosomal pH, as caused by the polycyclic amine compounds.
    Antiviral research 06/2013; · 3.61 Impact Factor
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    ABSTRACT: BACKGROUND: Cidofovir (CDV) proved efficacious in treatment of human papillomaviruses (HPVs) hyperplasias. Antiproliferative effects of CDV have been associated with apoptosis induction, S-phase accumulation, and increased levels of tumor suppressor proteins. However, the molecular mechanisms for the selectivity and antitumor activity of CDV against HPV-transformed cells remain unexplained. METHODS: We evaluated CDV drug metabolism and incorporation into cellular DNA, in addition to whole genome gene expression profiling by means of microarrays in two HPV+ cervical carcinoma cells, HPV- immortalized keratinocytes, and normal keratinocytes. RESULTS: Determination of the metabolism and drug incorporation of CDV into genomic DNA demonstrated a higher rate of drug incorporation in HPV+ tumor cells and immortalized keratinocytes compared to normal keratinocytes. Gene expression profiling clearly showed distinct and specific drug effects in the cell types investigated. Although an effect on inflammatory response was seen in all cell types, different pathways were identified in normal keratinocytes compared to immortalized keratinocytes and HPV+ tumor cells. Notably, Rho GTPase pathways, LXR/RXR pathways, and acute phase response signaling were exclusively activated in immortalized cells. CDV exposed normal keratinocytes displayed activated cell cycle regulation upon DNA damage signaling to allow DNA repair via homologous recombination, resulting in genomic stability and survival. Although CDV induced cell cycle arrest in HPV- immortalized cells, DNA repair was not activated in these cells. In contrast, HPV+ cells lacked cell cycle regulation, leading to genomic instability and eventually apoptosis. CONCLUSIONS: Taken together, our data provide novel insights into the mechanism of action of CDV and its selectivity for HPV-transformed cells. The proposed mechanism suggests that this selectivity is based on the inability of HPV+ cells to respond to DNA damage, rather than on a direct anti-HPV effect. Since cell cycle control is deregulated by the viral oncoproteins E6 and E7 in HPV+ cells, these cells are more susceptible to DNA damage than normal keratinocytes. Our findings underline the therapeutic potential of CDV for HPV-associated malignancies as well as other neoplasias.
    BMC Medical Genomics 05/2013; 6(1):18. · 3.91 Impact Factor

Publication Stats

3k Citations
707.10 Total Impact Points


  • 2008–2013
    • Cardiff University
      • School of Pharmacy and Pharmaceutical Sciences
      Cardiff, WLS, United Kingdom
    • University of Barcelona
      • Instituto de Biomedicina (IBUB)
      Barcelona, Catalonia, Spain
  • 1989–2013
    • University of Leuven
      • • Department of Microbiology and Immunology
      • • Department of Biomedical Kinesiology
      Louvain, Flanders, Belgium
  • 2012
    • Warsaw University of Technology
      • Faculty of Chemistry
      Warsaw, Masovian Voivodeship, Poland
  • 2009–2012
    • University of Debrecen
      • Department of Pharmaceutical Chemistry
      Debrecen, Hajdu-Bihar, Hungary
  • 2009–2011
    • University of Queensland 
      • School of Chemistry and Molecular Biosciences
      Brisbane, Queensland, Australia
  • 2010
    • Polytech Paris-UPMC
      Lutetia Parisorum, Île-de-France, France
    • Istanbul University
      • Department of Pharmaceutical Chemistry
      İstanbul, Istanbul, Turkey
  • 2007–2010
    • Athens State University
      Athens, Alabama, United States
  • 2002–2010
    • Academy of Sciences of the Czech Republic
      • • Ústav organické chemie a biochemie
      • • Výzkumné centrum Gilead Sciences a ÚOCHB
      Praha, Hlavni mesto Praha, Czech Republic
    • University of Hamburg
      • Institute of Organic Chemistry
      Hamburg, Hamburg, Germany
  • 2007–2008
    • Pierre and Marie Curie University - Paris 6
      Lutetia Parisorum, Île-de-France, France
  • 2005
    • Catholic University of Louvain
      Walloon Region, Belgium
  • 2004
    • University of Wales
      Cardiff, Wales, United Kingdom
  • 1995–1998
    • University of Iceland
      • Institute of Biology
      Reikiavik, Capital Region, Iceland