Synthesis of a new N-9 ribityl analogue of cyclic inosine diphosphate ribose (cIDPR) as a mimic of cyclic ADP ribose (cADPR)

Article abstract of DOI:10.1081/NCN-200060041

A new analogue of cyclic inosine diphosphate ribose (cIDPR), in which the N-1 and N-9 ribosyl moieties were substituted by a carbocyclic moiety and a hydroxyl-alkyl chain, has been synthesized and characterized. Copyright Taylor & Francis, Inc.

Full text of DOI:10.1081/NCN-200060041

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SYNTHESIS OF A NEW N-9 RIBITYL ANALOGUE OF
CYCLIC INOSINE DIPHOSPHATE RIBOSE (cIDPR) AS A
MIMIC OF CYCLIC ADP RIBOSE (cADPR)
Giorgia Oliviero a , Jussara Amato a , Michela Varra a , Gennaro Piccialli a & Luciano Mayol a
a Dipartimento di Chimica delle Sostanze Naturali , Università di Napoli Federico II , Napoli,
Italy
Published online: 15 Nov 2011.
To cite this article: Giorgia Oliviero , Jussara Amato , Michela Varra , Gennaro Piccialli & Luciano Mayol (2005) SYNTHESIS OF
A NEW N-9 RIBITYL ANALOGUE OF CYCLIC INOSINE DIPHOSPHATE RIBOSE (cIDPR) AS A MIMIC OF CYCLIC ADP RIBOSE (cADPR),
Nucleosides, Nucleotides and Nucleic Acids, 24:5-7, 735-738, DOI: 10.1081/NCN-200060041
To link to this article: http://dx.doi.org/10.1081/NCN-200060041
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Nucleosides, Nucleotides, and Nucleic Acids, 24 (5–7):735–738, (2005)
Copyright D Taylor & Francis, Inc.
ISSN: 1525-7770 print/ 1532-2335 online
DOI: 10.1081/NCN-200060041
SYNTHESIS OF A NEW N-9 RIBITYL ANALOGUE OF CYCLIC
INOSINE DIPHOSPHATE RIBOSE (cIDPR) AS A MIMIC OF
CYCLIC ADP RIBOSE (cADPR)
Giorgia Oliviero, Jussara Amato, Michela Varra, Gennaro Piccialli, and
5
Luciano Mayol
Dipartimento di Chimica delle Sostanze Naturali, Universit`a di Napoli
Federico II, Napoli, Italy
5
A new analogue of cyclic inosine diphosphate ribose (cIDPR), in which the N-1 and N-9 ribosyl
moieties were substituted by a carbocyclic moiety and a hydroxyl-alkyl chain, has been synthesized and
characterized.
Keywords Cyclic ADP Ribose (cADPR), cIDPR, IP3
INTRODUCTION
Many cellular functions are modulated by the concentration of intracellular
calcium ions.[1] Two major mechanisms of calcium mobilization are known that
utilize calcium stored in cytoplasmic compartments for signalling. The release of
Ca2+ is triggered by the interaction of the second messenger, inositol 1,4,5-
triphosphate (IP3), with its receptor, a ligand-activated calcium-selective channel. A
second class of intracellular calcium-releasing channels is the ryanodine receptor.[2]
Although the physiological activator of this receptor is unknown, it can be activated
by Ca2+, causing the so called Ca2+-induced Ca2+ release (CICR). Recent research
establishes that, in addition to inositol triphosphate, the internal calcium stores can
be mobilized by new messenger molecules via cyclic ADP-ribose (cADPR,
Figure 1). cADPR that serves as a second messenger to activate the ryanodine
receptors of the sarcoplasmic reticulum and to mobilize intracellular Ca2+ in many
cell types in different species covering protozoa, plants, animals, and human.[3]
However, the mechanisms mediating the effect of cADPR remain unknown. Since
Ca2+ ions are regulators of several cell functions, muscle contraction, secretion
of neurotransmitters, hormones and enzymes, fertilization of ovocytes, and
Address correspondence to Giorgia Oliviero, Dipartimento di Chimica delle Sostanze Naturali, Universit`a di
Napoli Federico II, Napoli, Italy; E-mail: golivier@unina.it
735
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736
G. Oliviero et al.
FIGURE 1
lymphocyte activation and proliferation, the cADPR signaling pathway may
become a valuable target for pharmaceutical intervention.
cADPR is characterized by a very labile N-1 glycosidic bond which is rapidly
hydrolyzed both enzymatically, by cADP hydrolase, and non-enzymatically, to
give ADP-ribose even in neutral aqueous solution. This biological and chemical
instability deeply hinders further studies on cADPR aimed at elucidating its
physiological role, particularly as far as regulation of Ca2+mobilization in the cells is
concerned. Hence, stable yet active cADPR analogues are of great interest in this
field.[4]
In our laboratories we have previously synthesized two analogues of cADPR
(A and B, Figure 1).[5,6] These compounds, which display a carboribosyl and a
butyl moiety at N-1 and N-9 of a hypoxantine base, respectively, are designed to
investigate the role of a ribosyl moiety in the mechanism of Ca2+ intracellular
modulation. We wish to report here the synthesis of a new cIDPR analogue (C,
Figure 1) having a three-hydroxylated butyl chain at the N-9 of the hypoxanthine
base and a carboribosyl moiety at the N-1 position, which is expected to be
resistant to both enzymatic and chemical hydrolysis as are the similar N-1
alkylated analogues.
The synthetic strategy adopted for C is shown in Scheme 1. The 2’,3’-O-
isopropylidene-inosine 1 was allowed to react with DIBAL-H in anhydrous THF. In
this way the sugar moiety was reduced to afford the corresponding 1-D-ribitylinosine
derivative 2. Acetylation of the hydroxyl functions of 2 gave derivative 3. N-1

G. Oliviero et al.
737
SCHEME 1 Reagents and conditions: a) DIBAL-H, THF; b) Ac2O, pyridine, r.t.; c) NH4NO3, TFA, CH2Cl2,
0°C; d) 5, DMF, r.t.; 8 h; e) K2CO3, CH3OH, r.t.;15 min; f) S,S-diphenylphosphorodithioate, TPSCl, pyridine, N2,
r.t.; 8 h; g) AcAg, pyridine/H2O; h) EDC, NMP, r.t.; 60 h; i) aq. CH3CO2H, r.t.; 3.5 h.
nitroinosine derivative 4 was prepared according to the procedure proposed by
Vilarrasa and coworkers[7] by treatment of 3 with ammonium nitrate and tri-
fluoroacetic anhydride (TFAA) in dichloromethane. Derivative 6 could be ob-
tained by reaction of 4 with 5 in DMF as previously described.[5] Removal of the
acetyl protecting groups of 6 by treatment with K2CO3 in MeOH yielded 7. The
bis(phenylthio)phosphoryl groups were introduced on the primary hydroxyl
functions by treatment of 7 with S,S-diphenyl-phosphorodithioate (cyclohexylam-
monium salt) in the presence of 2,4,6-triisopropylbenzenesulphonylchloride
(TPSCl) and tetrazole in pyridine to give the protected bisphosphate derivative
8 as the main product together with the triphosphate derivative in a 8:2 ratio. After
HPLC (RP18) purification, 8 was treated with silver acetate (Ag Ac) for complete
removal of protecting groups of both phosphate residues. The deprotected
bisphosphate derivative 9 was further purified by HPLC (RP18) before cyclization,
which was performed as previously described,[6] to obtain 10 (50% yield after
purification). Finally, 10 was deprotected at phosphate residues by treatment with
acetic acid, which afforded the target compound C (10% overall yield starting from
1
1) whose structure was confirmed by H and 31P NMR and MS data.
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