NM 283, an efficient prodrug of the potent anti-HCV agent 2′-C-methylcytidine

Article abstract of DOI:10.1081/NCN-200060112

In order to improve the oral bioavailability of 2′-C-methylcytidine, a potent anti-HCV agent, the corresponding 3′-O-L-valinyl ester derivative (NM 283) has been synthesized. Based on its ease of synthesis and its physicochemical properties, NM 283 has emerged as a promising antiviral drug for treatment of chronic HCV infection. Copyright Taylor & Francis, Inc.

Full text of DOI:10.1081/NCN-200060112

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NM 283, AN EFFICIENT PRODRUG OF THE POTENT ANTI-
HCV AGENT 2′-C-METHYLCYTIDINE
C. Pierra a , S. Benzaria a , A. Amador b , A. Moussa c , S. Mathieu c , R. Storer b & G.
Gosselin a
a Laboratoire Coopératif Idenix—CNRS , Université Montpellier II , Montpellier Cedex 5,
France
b Laboratoire de Chimie Médicinale Idenix , Parc Euromedecine, rue Louis Pasteur ,
Montpellier, France
c Idenix Pharmaceutical Inc. , Cambridge, Massachusetts, USA
Published online: 15 Nov 2011.
To cite this article: C. Pierra , S. Benzaria , A. Amador , A. Moussa , S. Mathieu , R. Storer & G. Gosselin (2005) NM 283, AN
EFFICIENT PRODRUG OF THE POTENT ANTI-HCV AGENT 2′-C-METHYLCYTIDINE, Nucleosides, Nucleotides and Nucleic Acids,
24:5-7, 767-770, DOI: 10.1081/NCN-200060112
To link to this article: http://dx.doi.org/10.1081/NCN-200060112
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Nucleosides, Nucleotides, and Nucleic Acids, 24 (5–7):767–770, (2005)
Copyright D Taylor & Francis, Inc.
ISSN: 1525-7770 print/ 1532-2335 online
DOI: 10.1081/NCN-200060112
NM 283, AN EFFICIENT PRODRUG OF THE POTENT ANTI-HCV AGENT
2’-C-METHYLCYTIDINE
5
C. Pierra and S. Benzaria
Laboratoire Coope´ratif Idenix----CNRS, Universite´
Montpellier II, Montpellier Cedex 5, France
5
A. Amador
Laboratoire de Chimie Me´dicinale Idenix, Parc Euromedecine, rue Louis
Pasteur, Montpellier, France
5
A. Moussa and S. Mathieu
Idenix Pharmaceutical Inc., Cambridge, Massachusetts,
USA
5
R. Storer
Laboratoire de Chimie Me´dicinale Idenix, Parc Euromedecine, rue Louis Pasteur,
Montpellier, France
5
G. Gosselin
Laboratoire Coope´ratif Idenix----CNRS, Universite´ Montpellier II, Montpellier
Cedex 5, France
5
In order to improve the oral bioavailability of 2’-C-methylcytidine, a potent anti-HCV agent, the
corresponding 3’-O-L-valinyl ester derivative (NM 283) has been synthesized. Based on its ease of
synthesis and its physicochemical properties, NM 283 has emerged as a promising antiviral drug for
treatment of chronic HCV infection.
Keywords Hepatitis C Virus, 2’-C-Methyl Branched Nucleosides, Prodrugs
INTRODUCTION
Hepatitis C virus (HCV) has infected an estimated 170 million individuals, 3%
of the world’s population. There is no vaccine available against HCV, and current
therapies, subcutaneous interferon-a (IFN-a) monotherapy and IFN-a with oral
ribavirin combination, are expensive, often poorly tolerated, and effective only in
half of the patients population.
In our search for improved therapeutic agents against chronic hepatitis C, a
ribonucleoside analog, 2’-C-methylcytidine 4, was discovered to be a potent and
Address correspondence to G. Gosselin, Laboratoire Coop´eratif Idenix—CNRS, Universit´e Montpellier II,
Place Eug`ene Bataillon, Case Courrier 008, 34095 Montpellier Cedex 5, France; Fax: +33-4-6754-9610; E-mail:
gosselin@univ-montp2.fr
767
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768
C. Pierra et al.
SCHEME 1 Synthesis of 2’-C-methylcytidine.
selective inhibitor in cell culture of a number of related RNA viruses, including
bovine viral diarrhea virus (BVDV), yellow fever virus (YFV), and West Nile virus
(WNV).[1,2] In order to improve the oral bioavailability of 2’-C-methylcytidine, its 3’-
O-L-valinyl ester derivative (NM 283) has been synthesized.
We report here the chemical syntheses of both 2’-C-methylcytidine 4 and NM
283, as well as some physicochemical characteristics of NM 283.
CHEMISTRY
2’-C-methylcytidine 4 was synthesized using a strategy related to that reported
by Harry-O’kuru et al.[3] The precursor sugar 1 was easily accessible from
commercially available material. Condensation of this peracylated sugar 1 with
uracil, followed by removal of benzoyl groups under basic conditions, led to 2’-C-
methyluridine 3. Conversion of 3 via transient generation of its 4-nitrophenoxy
SCHEME 2 Synthesis of NM 283.

C. Pierra et al.
769
SCHEME 3 Alternative route to the synthesis of NM 283.
derivative,[4] followed by substitution with aqueous ammonia, led to the desired 2’-
C-methylcytidine 4 (Scheme 1).
A multi-step sequence involving dimethylaminomethylene protection[5] of the
exocyclic amino function, silylation[6] of the 5’-hydroxyl group, condensation with
N-tert-butyloxycarbonyl-L-valine (L-Boc-valine) using the coupling agent N’-(3-
dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (DEC) in the presence
of 4-dimethylaminopyridine (DMAP),[7] and total deprotection,[8] led to NM 283 as
its dihydrochloride salt (Scheme 2).
In our search for a more direct and scalable synthetic process, we then
developed a new synthetic strategy for the preparation of NM 283, based on the
direct condensation of 4 with L-Boc-valine, followed by removal of the N-tert-
butyloxycarbonyl group, thus reducing the number of the synthetic steps from 5 to
2. This time and labor saving process could be accomplished without involvement
of chromatographic purifications and NM 283 was obtained in high purity
following simple crystallization (Scheme 3).
PHYSICOCHEMICAL PROPERTIES
To be considered as a suitable prodrug for oral administration, NM 283 should
possess adequate solubility in aqueous media in order to dissolve in the small
intestine, and thus be available for absorption. Aqueous solubility of NM 283 has
been determined in comparison with the solubility of the parent nucleoside 4. Both
compounds are highly soluble in aqueous media (32 g/L for 4 and 423 g/L for NM
283), commensurate with their low distribution coefficient (log P) values: À0.965
and À1.34 for 4 and NM 283, respectively.
Stability studies of NM 283 were also carried out in order to determine whether
it would be sufficiently chemically stable in biological fluids and in the
gastrointestinal tract before its absorption. NM 283 appeared to be fully stable at
pH 1.2, but is hydrolyzed at pH 4.5 and 7.2 into the parent drug 4 following
first-order kinetics. The half-life of NM 283 at pH 4.5 and 7.2 is 6.1 days and
3.9 h, respectively.

770
C. Pierra et al.
CONCLUSION
NM 283, the 3’-O-valinyl ester derivative of 2’-C-methylcytidine, has been
synthesized in order to improve the oral bioavailability of the parent drug 2’-C-
methylcytidine. Based on its ease of synthesis and its physicochemical properties,
NM 283 has emerged as a promising antiviral agent for chronic HCV infection.
Further studies have revealed a good pharmacokinetic profile in monkey, and
promising results in human clinical trials.[9,10]
Expanded testing of NM 283, alone and in combination with interferon,
is anticipated.
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