Synthesis of C3-arylated-3-deazauridine derivatives with potent anti-HSV-1 activities

Article abstract of DOI:10.1016/j.bmcl.2012.10.047

A series of 3-deazauridines (3-DU) analogues were synthesized and evaluated in vitro for their antiherpetic activity against HSV-1 on Vero cell lines by cell viability. A first campaign of tests suggested that C3-arylated-3-DU derivatives could constitute a novel family of antiherpetic agents. A second campaign of biological evaluations led to the discovery of two potent anti-HSV-1 agents with comparable activity than acyclovir.

Full text of DOI:10.1016/j.bmcl.2012.10.047

Bioorganic & Medicinal Chemistry Letters 22 (2012) 7461–7464
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis of C3-arylated-3-deazauridine derivatives with potent
anti-HSV-1 activities
Julien Lalut a, Ludovic Tripoteau b, Christel Marty b, Hugo Bares a, Nathalie Bourgougnon b,
François-Xavier Felpin a,c, ,
⇑
a Université Bordeaux 1, UMR CNRS 5255, Institut des Sciences Moléculaires, 351 Cours de la Libération, 33405 Talence Cedex, France
b Université de Bretagne-Sud, PRES Université européenne de Bretagne, Laboratoire de Biotechnologie et Chimie Marines, Campus de Tohannic, 56017 Vannes, France
c Université de Nantes, CNRS UMR 6230, CEISAM, UFR des Sciences et des Techniques, 2 rue de la Houssinière, 44322 Nantes Cedex 3, France
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of 3-deazauridines (3-DU) analogues were synthesized and evaluated in vitro for their antiherp-
etic activity against HSV-1 on Vero cell lines by cell viability. A first campaign of tests suggested that C3-
arylated-3-DU derivatives could constitute a novel family of antiherpetic agents. A second campaign of
biological evaluations led to the discovery of two potent anti-HSV-1 agents with comparable activity than
acyclovir.
Received 14 September 2012
Revised 8 October 2012
Accepted 9 October 2012
Available online 24 October 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
3-Deazauridine analogues
Nucleoside
Anti-HSV-1
Antiherpetic
Herpes
Herpes simplex virus (HSV) infections are responsible of a wide
range of diseases in humans including genital and labial herpes
that could be life threatening for pregnant women, newborns
and immunocompromized patients. HSV infections is a common
human pathogen with between 60% and up to 95% of certain
populations infected with Herpes simplex virus type 1 (HSV-1),
and between 6 and 50% infected with Herpes simplex virus type 2
(HSV-2).1 The frequency of HSV-seropositive males was signifi-
cantly higher in populations infected with human immunodefi-
ciency virus (HIV).2 As HIV disease progresses, cutaneous and
mucosal complications become more severe and occur in up to
92% of HIV-infected individuals.3 Moreover, the recurrence of
infections upon various stimuli is severely damaging for patients.
The standard antiviral arsenal for the treatment of HSV infections
is mainly based on nucleoside-type drugs including acyclovir 1,
famcyclovir 2 and brivudin 3 (Fig. 1).4 These drugs have been
introduced at least 15 years ago and there is still a need for the
discovery of new agents with enhanced activities. While new heli-
case-primase inhibitors have been recently proposed as drug can-
didates for the treatment of HSV infections,5 nucleoside-based
O
N
N
N
N
N
N
NH
NH2
AcO
HO
N
NH2
O
Acyclovir : 1
Famcyclovir : 2
OAc
HO
OH
O
Br
NH
HO
N
O
N
O
O
O
OH
Brivudin : 3
OH OH
3-Deazauridine : 4
Figure 1. Structure of anti-HSV agents and 3-deazauridine 4.
agents are the only class of available drugs on the market due to
their unique pharmacological profile.
On the other hand 3-deazauridine (DU) 4 has been shown to in-
hibit cytidine triphosphate synthetase, thereby reducing intracel-
lular levels of cytidine triphosphate and disrupting DNA and RNA
synthesis.6 However, DU 4 used as a single agent exerts negligible
anti-tumoral clinical efficiency resulting in a lack of interest in
clinical investigation.7 Our interest in DU analogs stems from a
study describing that substitution at C3 position could led to
agents with anti-viral activities while cell toxicity remains weak.8
⇑
Corresponding author. Tel.: +33 251 125 422; fax: +33 251 125 402.
E-mail addresses: fx.felpin@univ-nantes.fr (F.-X. Felpin), fx.felpin@univ-nantes.fr
(F.-X. Felpin).
Present adress: Université de Nantes
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.10.047

7462
J. Lalut et al. / Bioorg. Med. Chem. Lett. 22 (2012) 7461–7464
Table 2
OBn
OBn
R-B(OH)2
Pd/C, Na2CO3
Evaluation of anti-HSV-1 activity on Vero cell line by neutral red dye method
I
R
O
1. Debenzylation
2. Glycosylation
Compounds
Vero EC50
l
Ma
Vero CC50
l
Mb
Efficiencyc (%)
iPrOH/H2O, 60°C
see reference 13
N
O
N
Bn
Acyclovir
7a
7b
7c
7d
7e
7f
8a
8b
8c
8d
8e
8f
0.76
>100
10.5
>400
>400
>400
>400
>400
>400
>400
>400
>400
>400
>400
>400
>400
100
ND
7.2
ND
2.1
ND
ND
ND
3.8
ND
ND
ND
ND
Bn
6
5
OH
R
OH
R
>100
36.6
>100
>100
>100
20.0
>100
>100
>100
>100
AcO
HO
N
O
N
O
Acetolysis
O
O
OAc OAc
OH OH
7
8
Scheme 1. General strategy for the preparation of C3-arylated-3-deazauridine
compounds.
a
Represents the concentration that achieves 50% protection of virus-infected
cells from the HSV-induced destruction.
However, only 3-nitro-3-deazauridine was active and no other ac-
tive compound was disclosed. We assumed that other substitution
at C3 with sterically hindered and/or appropriate functional groups
can modify interactions associated with base pairing and protein
receptor binding. In this context, we felt that substitution at C3
by aryl groups could lead to a new class of nucleosides. Such a
strategy has been recently studied on other systems9 and lead to
new promising anti-viral and cytostatic agents10 as well as fluores-
cent probes.11 Only a few papers deals with the synthesis of 3-DU
analogues,12 and to the best of our knowledge, no work has been
disclosed concerning the arylation of 3-DU 4. In this communica-
tion we report our last finding that led to the discovery of a new
family of C3-arylated-3-deazauridine derivatives displaying potent
anti-HSV-1 activities.
b
Represents the concentration that reduces the absorbance of mock-infected
cells to 50% of that of control.
c
The efficiency is expressed in % as the ratio of EC50 for acyclovir relative to the 3-
DU analogues.
as benzylated nucleobases for the preparation of novel nucleosides
as depicted in the Scheme 1.
In this context, we initially prepared six benzylated nucleobases
6a–f13for the design of new potential antiherpetic 3-DU analogues
(Table 1). The benzyl group of compounds 6a–f was cleaved under
standard conditions with the Pearlman’s catalysts and the corre-
sponding deprotected products were immediately reacted with
the tetra-O-acetyl-D
-ribose 9 under Vorbrüggen conditions14 to
give the acetylated nucleosides 7a–f. The modest yield obtained
for nucleoside 7c could be explained by partial instability of the
methylenedioxy group in the presence of the strong Lewis acid,
In a recent paper we reported the rapid preparation of 3-aryl-4-
oxypyridin-2-(1H)-ones 6 through a practical Pd/C-catalyzed Suzu-
ki–Miyaura reaction.13 These useful intermediates can be viewed
Table 1
Preparation of the first generation anti-HSV-1 nucleosides
OH
N
OH
N
R
O
R
O
OBn
1. H2, Pd/C
AcO
HO
R
CH3COOH
K2CO3
MeOH
O
O
2. BSA, CH3CN
TMSOTf
N
Bn
O
OAc OAc
OH OH
AcO
OAc
6a-f
O
8a-f
7a-f
9
OAc OAc
O
O
OCH3
RO
OH
OH
OH
N
O
RO
RO
N
O
N
O
O
O
O
OR OR
OR OR 7a - 64%a
8a - 80%
7b - 65%a
OR OR
7c - 45%a
8b
8c
- 82%
- 90%
OCH3
OH
OH
OH
OCH3
RO
RO
N
O
N
O
RO
N
O
O
O
O
7d - 60%a
8d - 85%
7e - 65%a
8e - 71%
7f - 54%a
8f - 77%
OR OR
OR OR
OR OR
aYield over two steps.

J. Lalut et al. / Bioorg. Med. Chem. Lett. 22 (2012) 7461–7464
7463
TMSOTf. The acetyl functions of compounds 7a–f were then re-
moved by methanolysis to afford the free nucleoside 8a–f.
this first campaign of synthesis, three of them displayed interesting
anti-HSV-1 activity with an EC50<50 M. For instance, at a multi-
plicity of infection (MOI) of 0.001 ID50/cells, 85% cellular protection
was obtained for 200 g/ml of 7b at 72 h after infection and 82%
cellular protection was obtained for 200 g/ml of 8b at 72 h after
infection. For 7d, 75% cellular protection was obtained at 200 g/
ml. It is worth mentioning that acylated nucleosides display a
higher activity relative to their deprotected congeners. Although
these results were very encouraging for the discovery of a lead,
the efficiency, relative to the selected drug of reference (acyclovir),
still remained to be improved.
l
Having led the foundation of a solid synthetic pathway for the
preparation of C3-functionnalized-3-DU compounds we carried
out preliminary biological evaluations. The antiviral properties
against HSV-1 on Vero cell line of our set of 12 nucleosides (7a–f
and 8a–f) were evaluated and the results are reported in the Table
2. In comparison with Vero cell lines, after 3 days of treatment,
microscopically visible alteration of normal cell morphology was
observed and viability assay showed destruction of cell layer. The
range of concentrations assayed for all compounds tested on Vero
l
l
l
cell lines corresponds to 200, 50, 10, 5, 1
l
g/ml. No cytotoxic effect
Motivated by the promising results reported above, we engaged
a second campaign of synthesis of anti-HSV-1 nucleosides with a
higher molecular diversity. Toward this end, we prepared a variety
of C3-, C5- and C6-subtituted 3-DU taking advantage of the meth-
of the compounds on the Vero cells was observed in the range of
the concentrations assayed for all compounds. But more impor-
tantly, among the set of compounds prepared (7a–f and 8a–f) in
Table 3
Preparation of the second generation of anti-HSV-1 nucleosides
OH
N
OH
N
R2
R3
R1
O
R2
R3
R1
O
OBn
1. H2, Pd/C
CH3COOH
R2
R3
R1
AcO
HO
K2CO3
MeOH
O
O
2. BSA, CH3CN
TMSOTf
N
Bn
O
OAc OAc
OH OH
AcO
OAc
6g-r
O
8g-r
7g-r
9
OAc OAc
OCH3
OCF3
OCH3
RO
OCH3
OH
OH
OH
OCH3
RO
N
O
RO
N
O
N
O
O
O
O
OR OR
OR OR 7g - 67%a
OR OR 7h
7i
8i
a
a
- 35%
- 62%
b
8g
- 69%
8h
- 63%
- ND
OEt
RO
SO2Me
RO
OH
OH
OH
RO
N
O
N
O
O
N
O
O
O
7j - 59%a
7k - 63%a
7l - 77%a
OR OR
OR OR
OR OR
b
8j
8k
8l
- 41%
- 95%
- ND
OH
OH
OH
RO
RO
N
O
N
O
RO
N
O
O
O
O
a
a
c
OR OR 7m
OR OR 7n
7o
- 89%
- 62%
- 60%
OR OR
8m - 30%
8n - 77%
8o - 96%
H3CO
OEt
OH
OH
OH
RO
RO
N
O
N
O
RO
N
O
O
O
O
c
a
c
OR OR 7p
OR OR 7q
7r
OR OR
- 58%
- 50%
- 46%
8p - 73%
8q - 83%
8r - 61%
a
b
c
Yield over two steps
Not determined due to extensive decomposition
Yield of the glycosidation step, see text.

7464
J. Lalut et al. / Bioorg. Med. Chem. Lett. 22 (2012) 7461–7464
Table 4
could also play a crucial role since the nucleoside 7l, bearing a
tert-butyl group, was inactive. The elucidation of the mechanism
of action could help us in determining the interactions with the
biological target.
Evaluation of anti-HSV-1 activity on vero cell line by neutral red dye method
Compounds
Vero EC50
l
Ma
Vero CC50
l
Mb
Efficiency (%)c
Acyclovir
4
7b
7d
7g
7h
7i
7j
7k
71
7m
7n
7o
7p
7q
7r
8b
8g
8h
8j
22
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
>200
100
ND
ND
ND
ND
ND
ND
ND
ND
ND
45
The discovery of new antiherpetic agents, able to substitute
ageing marketed drugs, is still of need for public health consider-
ation. In this work we have disclosed a new family of potent
anti-HSV-1 nucleosides, analogues to the well known 3-deazauri-
dine 4. From the preparation and the biological evaluations of more
than thirty C3-arylated-3-DU derivatives, two compounds
emerged as potential antiherpetic agents. Further studies toward
the determination of the mechanism of action are currently under-
way and should provide us essential information for the design of
agents with an improved biological profile.
>100
>100
>100
>100
>100
>100
>100
>100
>100
49
33
67
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Acknowledgments
We gratefully acknowledge the ‘Université de Bordeaux’, the
‘Université de Nantes’, the ‘Centre National de la Recherche Scien-
tifique (CNRS)’, and Aquitaine Valo for their financial support.
81
8m
8n
8o
8p
8q
8r
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2012.10.
047.
a
Represents the concentration that achieves 50% protection of virus-infected
cells from the HSV-induced destruction.
References and notes
b
Represents the concentration that reduces the absorbance of mock-infected
cells to 50% of that of control.
The efficiency is expressed in % as the ratio of EC50 for acyclovir relative to the 3-
DU analogues.
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the second generation of nucleosides prepared are reported in the
Scheme 3. It should be noted that the nucleobases of compounds
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toxic effect on Vero cell lines at concentration as high as 200 lM.
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