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ACS Medicinal Chemistry Letters
(b) Disposition of Lꢀ742,001 in PAꢀNter as predicted by dockꢀ
ABBREVIATIONS
1
2
3
ing: the conformer representing the most favorable binding enꢀ
ergies (in blue) and that representing the most diffuse population
of conformers (in pink).19
RdRp, RNAꢀdependent RNA polymerase complex; PAꢀNter, Nꢀ
terminal part of PA; PAI, PA inhibitor; vRNA, viral RNA;
DKA, βꢀdiketoacid; VS, virtual screening.
4
5
6
7
8
9
To summarize, a large database of roughly 5 million strucꢀ
tures was screened to identify novel influenza virus endonuꢀ
clease inhibitors applying pharmacophore and structureꢀ
based docking procedures. Fifteen hits were then evaluated
in a PAꢀNter enzymatic assay, and three compounds bearing
an original bisꢀdihydroxyꢀ1Hꢀindoleꢀ2ꢀcarboxamide scaffold
demonstrated interesting inhibitory activity, with compounds
10 and 15 having IC50 values in the low micromolar range.
Both prototypes also showed antiviral activity in cellꢀbased
assays, and had comparable potency compared to the referꢀ
ence PAI Lꢀ742,001 and the nucleoside analogue inhibitor
ribavirin. Followꢀup studies are warranted to further assess
the full potential of the bisꢀdihydroxyꢀ1Hꢀindoleꢀ2ꢀ
carboxamide scaffold to develop new influenza PAIs with
preclinical relevance.
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ASSOCIATED CONTENT
Supporting Information. Synthetic and computational procedures.
Influenza plasmidꢀbased endonuclease, virus yield, and vRNP reꢀ
constitution assays. This information is available free of charge via
AUTHOR INFORMATION
Corresponding Author
* Dr. Nicolino Pala
Dipartimento di Chimica e Farmacia
Università di Sassari
Via Vienna 2, 07100 Sassari, ITALY
Phone: +39 079 228 654; Fax: +39 079 229559
*Dr. Lieve Naesens
Rega Institute for Medical Research,
Laboratory of Virology and Chemotherapy
KU Leuven,
Bꢀ3000 Leuven, Belgium
Minderbroedersstraat 10
Phone: +32ꢀ16ꢀ337345
Author Contributions
(11) Das, K.; Aramini, J. M.; Ma, L. C.; Krug, R. M.; Arnold, E.
Structures of influenza A proteins and insights into antiviral
drug targets. Nat. Struct. Mol. Biol. 2010, 17, 530ꢀ538.
(12) Rogolino, D.; Carcelli, M.; Sechi, M.; Neamati, N. Viral
The manuscript was written through contributions of all authors. All
authors have given approval to the final version of the manuscript.
These authors contributed equally.
enzymes containing magnesium: Metal binding as
a
Funding Sources
successful strategy in drug design. Coord. Chem. Rev. 2012,
256, 3063ꢀ3086.
The authors confirm that this article content has no conflict of interꢀ
est. The authors thank the Fondazione Banco di Sardegna (grant to
M.S), the KU Leuven (grant Geconcerteerde Onderzoeksacties,
GOA/15/019/TBA) (to A.S. and L.N.), and the Italian Ministero
dell’Istruzione, dell’Università e della Ricerca (PRIN 2010, grant
2010W2KM5L_003) (to M.S, D.R, and M.C.) for their financial
support.
(13) Tomassini, J. E.; Selnick, H.; Davies, M. E.; Armstrong, M.
E.; Baldwin, J.; Bourgeois, M.; Hastings, J. C.; Hazuda, D.;
Lewis, J.; McClements, W.; Ponticello, G.; Radzilowski, E.;
Smith, G.; Tebben, A.; Wolfe, A. Inhibition of cap
(m7GpppXm)ꢀdependent endonuclease of influenza virus by
4ꢀsubstituted
2,4ꢀdioxobutanoic
acid
compounds.
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(14) Hastings, J. C.; Selnick, H.; Wolanski, B.; Tomassini, J. E.
Antiꢀinfluenza virus activities of 4ꢀsubstituted 2,4ꢀ
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Mojena, M.; Raghoobar, S. L.; Singh, S. B.; Tkacz, J. S.;
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ACKNOWLEDGMENT
The authors thank Dr. Andrea Brancale for the use of MOE proꢀ
gram. A.S. and L.N. acknowledge Wim van Dam and Ria Van
Berwaer for fine technical assistance, and Meehyein Kim (Koꢀ
rea Research Institute of Chemical Technology, Daejeon, South
Korea) for generous donation of the vRNP reconstitution plasꢀ
mids.
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