New synthetic AICAR derivatives with enhanced AMPK and ACC activation

Article abstract of DOI:10.3109/14756366.2015.1063622

5-Aminoimidazole-4-carboxamide riboside (AICAR) has an important role in the regulation of the cellular metabolism showing a broad spectrum of therapeutic activities against different metabolic processes. Due to these proven AICAR properties, we have desi

Full text of DOI:10.3109/14756366.2015.1063622

Journal of Enzyme Inhibition and Medicinal Chemistry
ISSN: 1475-6366 (Print) 1475-6374 (Online) Journal homepage: http://www.tandfonline.com/loi/ienz20
New synthetic AICAR derivatives with enhanced
AMPK and ACC activation
Olga Scudiero, Ersilia Nigro, Maria Ludovica Monaco, Giorgia Oliviero, Rita
Polito, Nicola Borbone, Stefano D'Errico, Luciano Mayol, Aurora Daniele &
Gennaro Piccialli
To cite this article: Olga Scudiero, Ersilia Nigro, Maria Ludovica Monaco, Giorgia Oliviero, Rita
Polito, Nicola Borbone, Stefano D'Errico, Luciano Mayol, Aurora Daniele & Gennaro Piccialli
(2015): New synthetic AICAR derivatives with enhanced AMPK and ACC activation, Journal of
Enzyme Inhibition and Medicinal Chemistry, DOI: 10.3109/14756366.2015.1063622
To link to this article: http://dx.doi.org/10.3109/14756366.2015.1063622
Published online: 08 Oct 2015.
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ISSN: 1475-6366 (print), 1475-6374 (electronic)
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2015 Taylor & Francis. DOI: 10.3109/14756366.2015.1063622
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RESEARCH ARTICLE
New synthetic AICAR derivatives with enhanced AMPK and ACC
activation
Olga Scudiero1,2, Ersilia Nigro1, Maria Ludovica Monaco1, Giorgia Oliviero3, Rita Polito1, Nicola Borbone3,
Stefano D’Errico3, Luciano Mayol3, Aurora Daniele1,4, and Gennaro Piccialli3,5
1CEINGE – Advanced Biotechnologies S.C a r.l., Napoli, Italy, 2Department of Molecular Medicine and Medical Biotechnologies and 3Department of
Pharmacy, University of Naples Federico II, Napoli, Italy, 4Department of Environmental Biological and Pharmaceutical Sciences and Technologies,
5
Second University of Naples, Caserta, Italy, and Institute of Protein Biochemistry, Napoli, Italy
Abstract
Keywords
5-Aminoimidazole-4-carboxamide riboside (AICAR) has an important role in the regulation of
the cellular metabolism showing a broad spectrum of therapeutic activities against different
metabolic processes. Due to these proven AICAR properties, we have designed, synthesized
and tested the biological activity of two ribose-modified AICAR derivatives, named A3 and A4,
in comparison to native AICAR and its 50-phosphorylated counterpart ZMP. Our findings have
shown that A3 and A4 derivatives induce the phosphorylation of 50-AMP activated protein
kinase a (AMPKa), which leads to the inhibition of acetyl-CoA carboxylase (ACC), and down-
regulate the activity of the extracellular signal-regulated kinases (ERK1/2). Cytotoxicity tests
demonstrated that A3 and A4 do not significantly reduce cell viability up to 24 h. Taken
together our results indicate that A3 and A4 have a comparable activity to AICAR and ZMP
at 0.5 and 1 mM suggesting their potential use in future pharmacological strategies relating
to metabolic diseases.
AICAR, AMPK, ACC, cell lines cytotoxicity,
p-ERK1/2
History
Received 1 April 2015
Revised 7 May 2015
Accepted 11 May 2015
Published online 6 October 2015
Introduction
signaling events1–4. Unfortunately, AICAR shows some limita-
tions: it has a short half-life in cells; it does not cross efficiently
the blood-brain barrier and it is poorly absorbed by the
gastrointestinal tract. These considerations, as well as the
presence of some side effects in the administration of AICAR10,
have stimulated the research of new structurally related deriva-
tives/analogues with improved and well-targeted biological
properties.
During the last two decades, metabolic diseases have become
the most common chronic disease group worldwide1. 5-
Aminoimidazole-4-carboxamide riboside (AICAR) is a potent
activator of 50-AMP activated protein kinase (AMPKa), a protein
kinase that increases fatty acid oxidation in multiple tissues and
also stimulates the uptake and the transport of glucose as well as
glycolysis2–4. At the same time, the activation of AMPKa also
results in inhibitory effects on lipogenesis in the liver in an
opposite manner compared to those of insulin. In muscle and
liver, the activation of AMP leads to the inactivation of acetyl-
CoA carboxylase (ACC) increasing fatty acid oxidation and
inhibiting triacylglycerol synthesis. The AMPKa pathway is also
implicated in the regulation of cell proliferation and its activation
by AICAR could result in pro-apoptotic events5–8. In addition,
AICAR can also exert an influence on the extracellular signal-
regulated kinase (ERK1/2), a protein involved in cell proliferation
whose regulation plays an important and widely investigated role
in anti-cancer approaches9. Therefore, AICAR could be con-
sidered as an important tool in the treatment of obesity and related
co-morbidities.
To achieve this aim, following on from previous studies11,12
,
we have designed and synthesized two new ribose-modified
AICAR derivatives, named A3 and A4, that can be considered
more lipophilic AICAR analogues (Figure 1). We have evaluated
some metabolic effects of these compounds on A549, HepG2 and
C2C12 cell lines verifying the phosphorylation status of AMPKa
and ACC and the regulation of the ERK1/2 enzyme. Furthermore,
we have investigated the cytotoxicity effects of A3 and A4 and
evaluated their stability in human serum. We anticipate here that
these AICAR derivatives activate AMPKa, and ACC probably via
AMPKa and down-regulate ERK1/2. Furthermore, we have
demonstrated that both A3 and A4 were not toxic for cells up
to 24 h.
In this context, we have focused on AICAR due to its direct or
indirect involvement with a number of important metabolic or
Methods
Reagents and synthesis
Solid support 1 (Scheme 1) exploits a 4-methoxytrityl chloride
resin (MMTCl, 1% divinylbenzene, 200–400 mesh, 1.3 mmol/g
loading) which was purchased from CBL (Greece)13. All reagents
Address for correspondence: Dr Giorgia Oliviero, Dipartimento di
`
Farmacia, Universita degli Studi di Napoli Federico II, Via Domenico
Montesano 49, 80131, Napoli, Italy. E-mail: golivier@unina.it

2
O. Scudiero et al.
J Enzyme Inhib Med Chem, Early Online: 1–6
Figure 1. Structures of AICAR and ZMP and
derivatives A3 and A4.
Scheme 1. Reagents and conditions: (i)
DNCB, K2CO3, DMF, 80ꢁC, 3 h; (ii) EDA,
DMF, 50ꢁC, 8 h; (iii) TFA (2% in dry DCM),
r.t., 8 min.
were obtained from commercial sources (Sigma-Aldrich, Synthesis of A4
Germany) and were used without further purification. The
To the solid support 1 (1.0 g, 0.87 mmol) suspended in dry DMF
(20 mL), K2CO3 (0.9 g, 6.5 mmol) and 2,4-dinitrochlorobenzene
(DNCB; 1.9 g, 6.5 mmol) were added and the mixture kept at
80 ꢁC for 3 h. After filtration, the support was washed with DMF
(3 ꢀ 5 mL), DMF/H2O (1:1, v/v, 3 ꢀ 5 mL), H2O (3 ꢀ 5 mL),
H2O/MeOH (1:1, v/v, 3 ꢀ 5 mL) and MeOH (3 ꢀ 5 mL) and
then dried under reduced pressure to give support 2 (0.76 mmol/
g). The reaction yield (94%) was evaluated by detaching 1-(2,4-
dinitrophenyl) inosine from a weighed amount of support 2 under
acid hydrolytic conditions [TFA/H2O/DCM (3:2:95, v/v/v,
15 min, r.t)] followed by MeOH washings (collected). Then the
solid support 2 (0.10 g, 0.076 mmol) was swollen in DMF and left
in contact with ethylenediamine (5.0 mmol) in DMF (1.5 mL)
under shaking for 8 h at 50 ꢁC. After filtration and washings with
DMF (3 ꢀ 5 mL), DMF/MeOH (1:1, v/v, 3 ꢀ 5 mL) and MeOH
(3 ꢀ 5 mL) the obtained support 3 was dried under reduced
reactions on solid phase were performed using glass columns
(10 mm diameter, 100 mm length) with fused-in sintered glass-
disc PO (bore of plug 2.5 mm), which were shaken in an orbital
shaker, or in round-bottomed flasks, when the reactions required
high temperatures. The 1H-NMR spectra were recorded on a
Varian Mercury Plus 400 MHz in CD3OD as solvent. The
chemical shifts were reported in parts per million (ꢀ) relative to
the residual solvent signal (1H: CD2HOD 3.31; 13C: CD3OD
49.0). The abbreviations s, d and m stand for singlet, doublet and
multiplet, respectively. The UV spectra were recorded on a Jasco
V-530 UV spectrophotometer. The High Resolution MS spectra
were recorded on a Bruker APEX II FT-ICR (9.4 T) mass
spectrometer using electrospray ionization (ESI) in positive mode.
Synthesis of A3
5-Aminoimidazole-4-carboxamide riboside (AICAR; 100 mg, pressure. The product A4 was obtained treating a weighed amount
0.39 mmol) was dissolved in a solution of acetic anhydride in of support 3 with a 2% TFA solution in anhydrous DCM (v/v,
pyridine (3:7, v/v, 1 mL, 15 h, r.t.). The crude, dried under reduced 8 min, r.t.), followed by DMF washings (collected). The crude A4
pressure, was purified on a silica gel column eluted with was purified by preparative HPLC using a C-18 reverse-phase
increasing amounts of CH3OH in DCM (from 0% to 10%). The column (Merck, 250 mm ꢀ 10 mm, particle size 10 mm) eluted
fractions eluted with 10% of CH3OH were collected and then with a linear gradient of CH3CN in H2O (from 0% to 100% in
evaporated, affording pure A3 (142 mg, 95%) as a foam. El. An. 60 min, flow 1.3 mL/min).
Calcd. for C15H20N4O8: C, 46.88; H, 5.25; N, 14.58. Found: C,
In particular, 50 mg of support 3 furnished 16 mg of pure 20,30-
46.92; H, 5.28; N, 14.62. 1H-NMR (400 MHz, CD3OD) d 7.40 (s, O-(4-hydroxymethyl-(1R)-benzyliden)-AICA riboside A4. El. An.
1H, 2-H), 5.88 (d, J ¼ 6.6 Hz, 1H, 10-H), 5.58 (m, 1H, 20-H), 5.37 Calcd. for C17H20N4O6: C, 54.25; H, 5.36; N, 14.89. Found: C,
1
(m, 1H, 30-H), 4.48–4.27 (complex signal, 3H, 2 ꢀ 50-Ha,b and 54.28; H, 5.38; N, 14.87. H-NMR (400 MHz, CD3OD) ꢀ 7.55
40-H), 2.14 (s, 3H, CH3), 2.10 (s, 3H, CH3), 2.06 (s, 3H, CH3). (d, J ¼ 8.1 Hz, 2H, arom.), 7.41 (d, J ¼ 8.1 Hz, 2H, arom.), 7.38
13C-NMR (100 MHz, CD3OD) d 170.6, 170.4, 170.1, 167.5, (s, 1H, 2-H), 6.04 (s, 1H, CH), 5.90 (d, J ¼ 3.8 Hz, 1H, 10-H),
136.8, 133.3, 115.7, 88.0, 80.9, 73.1, 72.6, 62.1, 21.3, 21.0, 20.8; 5.26–5.21 (m, 1H, 20-H), 5.09–5.04 (m, 1H, 30-H), 4.64 (s, 2H,
UV (MeOH) lmax 267 nm; m/z 407.1184 (HRESIMS) ([M + Na]+, CH2OH), 3.82–3.77 (m, 2H, 50-Ha,b). 13C-NMR (100 MHz,
requires 407.1179).
CD3OD) ꢀ 167.8, 143.8, 143.2, 134.9, 129.4, 126.7, 126.4,

DOI: 10.3109/14756366.2015.1063622
New AICAR derivatives with enhanced AMPK and ACC activation
3
112.4, 107.9, 90.7, 85.0, 82.8, 81.9, 63.3, 60.9; UV lmax 268 nm; Results
m/z 377.1461 (HRESIMS) ([M + H]+, requires 377.1467).
Synthesis of A3 and A4 derivatives
The AICAR-triacetate A3 was produced using acetic anhydride in
pyridine as acetylating agent on AICAR and the structure and
purity were ascertained by 1H NMR and HPLC, respectively. The
derivative A4 was synthesized by exploiting a solid-phase
procedure successfully used in our laboratory to produce several
derivatives13,16,17. The solid support 1 (Scheme 1), containing the
50-acetyl-inosine moiety with a loading of 0.87 mmol/g, was
activated on the purine base by installing the 2,4-dinitrophenyl
group on the N-1 position thus obtaining the support 2. In fact,
this aromatic group is a strong electron-withdrawer and renders
the C-2 purine atom very reactive towards the ethylenediamine
(EDA), which is a reagent that can degrade the purine to 5-
aminoimidazole-4-carboxamide (AICA). The reaction with EDA
Cell culture
Cell lines derived from human lung (A549), human liver (HepG2)
and murine muscle (C2C12) were obtained from the Bank of
Human and Animal Continuous Cell Lines-CEINGE
Biotecnologie Avanzate, Naples, Italy. The cells were grown in
DMEM (Sigma-Aldrich St. Louis, MO) supplemented with 10%
fetal bovine serum (FBS; Lonza Basel, Switzerland) and 1%
L-glutamine (Sigma-Aldrich). The cells were grown in the flask at
37 ꢁC in a 5% CO2 as a monolayer.
Western Blotting analysis
Western Blotting analysis was performed as previously additionally removed the 50-acetyl protecting group, furnishing
described14. Briefly, after 12 h starvation A549, HepG2 and the 20,30-O-(4-hydroxymethyl-(1R)-benzylidene)-AICA riboside
C2C12 cells (5 ꢀ 104 cells/4 mL) were treated for 2 h with 3. Finally, the acid treatment on the support 3 with trifluoroacetic
AICAR, ZMP, A3 and A4 (0.5 and 1.0 mM). After incubation, acid (TFA, 2% in DCM) in anhydrous conditions allowed the
proteins were extracted and separated as previously described14. release of the 20,30-O-(4-hydroxymethyl-benzylidene)-AICA ribo-
The membranes were incubated with GAPDH (SantaCruz- side A4 in an overall yield of 66% (from support 1). Starting from
Biotechnology, Santa Cruz, CA), pACC; p-AMPKa, AMPKa 50 mg of support 1, 16 mg of A4 were obtained after HPLC
(Cell-Signaling Technology, Danvers, MA) antibodies according purification. The structure of A4 was confirmed by 1H NMR and
to the manufacturer’s instructions. Proteins were transferred to MS analyses. Compound A4 proved to be a pure stereoisomer
PDVF membranes (Millipore Corporation, Billerica, MA) and possessing the R configuration at the benzylidene acetal carbon.
probed overnight with the appropriate dilution of primary In fact, the 2D-NOESY experiments on A4 confirmed that the
antibodies: pACC, p-AMPKa, AMPKa polyclonal antibodies acetal carbon retains the R configuration present on the native
(Cell Signalling Technology, Inc., Danvers, MA), according to the benzylidene-acetal-inosine 1 and that no racemization events
manufacturer’s instructions. The gel was exposed to high-per- occur during the TFA treatment on 318.
formance autoradiography film (Amersham Biosciences,
Piscataway, NJ), digitalized with a scanner (1200 dpi) and
AICAR derivatives A3 and A4 activate AMPKa inhibiting
analyzed by densitometry with the Jasc Paint Shop Pro 7.00
ACC
software (Corel Corporation, Ottawa, Ontario, Canada). All
experiments were performed in triplicate.
We investigated the effects of A3 and A4 on the phosphorylation
status of AMPKa validating the results using AICAR and ZMP as
positive controls. Cells were treated with two different amounts of
AICAR, ZMP and derivatives (0.5 and 1.0 mM) for 2 h. As shown
MTT colorimetric test: proliferation assay
The 3-[4,5-dimethylthiazol-2-yl]-2,5-dipheniltetrazolium-brom- in Figure 2, both A3 and A4 were able to phosphorylate AMPKa
ide (MTT) test was performed as previously described15. in A549, HepG2 and C2C12 cell lines to almost the same extent
Briefly, after 12 h starvation, A549, HepG2 and C2C12 cell as AICAR and ZMP (p50.05).
lines (4 ꢀ 103 cells/100 mL per well) were incubated with or
To further investigate the activity of the new AICAR deriva-
without AICAR and its derivatives (1 mM). After 24, 48 and 72 h tives, we also determined the phosphorylation status of ACC. The
of incubation, the cells were stained with MTT/PBS solution. The results obtained show that A3 and A4 treatment is associated with
experiments were performed two times in triplicate.
the phosphorylation of ACC probably via AMPKa (p50.05;
Figure 2, panel B and C, respectively). In the A549 cells, we did
not detect any signals corresponding to ACC probably due to the
sensibility of the methodology or due to the lack of any detectable
ACC expression. Our data derive from the comparison between
untreated and treated cells and confirm the role of AICAR and
ZMP as potent AMPKa activators. Moreover, we have demon-
strated that A3 and A4 have a similar behavior because they both
stimulate the phosphorylation of AMPKa. Finally, we found an
over-phosphorylation of ACC in treated cells, probably associated
with p-AMPKa activation.
Serum stability
Serum stability was performed as previously described15. Briefly,
10 mL of a 0.5 mM solution of A3 and A4 derivatives were
incubated in human serum/TBS (4:1, v/v) at 37 ꢁC and the
hydrolytic effects were analyzed by HPLC injecting 10 mL of
solution every 15 min. The products were identified by comparison
with authentic samples. The analysis were performed using an
HPLC apparatus (Jasco PU-2089, equipped with an UV/Vis
detector plus-2075) and using a RP18 column (Nucleosil-100,
Macherey-Nagel, 250 mm ꢀ 4.60 mm, 10 m) eluted with an increas-
ing amount of acetonitrile in water (linear gradient from 0% to
100%, v/v, in 60 min, flow rate 0.5 mL/min, wavelength 254 nm).
Cytotoxicity of AICAR, ZMP and A3 and A4 derivatives on
A549, HepG2 and C2C12 cell lines
To define the cytotoxic effects of A3 and A4, we incubated these
derivatives at 1.0 mM concentration on A549, HepG2 and C2C12
cell lines. We observed that A3 and A4, after 24 h of treatment,
did not statistically affect cell viability. Instead, after 48 and 72 h
of incubations A3 and A4 reduced cell viability (50–60%). These
experiments showed that AICAR, ZMP, A3 and A4 do not induce
relevant cytotoxic effects in vitro up to 24 h (Figure 3). At 48 and
Statistical analysis
Data are expressed as means SD and medians. Two groups were
compared with 2-tailed unpaired Student’s t-test. Multiple com-
parisons were evaluated by one way analysis of variance
(ANOVA). The statistical significance was established at p50.05.

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O. Scudiero et al.
J Enzyme Inhib Med Chem, Early Online: 1–6
Figure 2. Graphical representation of pixel
quantization of p-AMPK in A549, HepG2
and C2C12 cells and one representative WB
image of p-AMPK, p-ACC and GAPDH. For
other details see materials and methods. WB,
western blot. Asterisks indicate statistical
differences between control and treatments
p50.05. CN: untreated cells.
72 h, A3 and A4 showed cytotoxic effects to almost the same could be detected after 48 h of A4 incubation in serum. The
extent as AICAR and ZMP.
analyses were performed by HPLC comparison with authentic
samples.
Serum stability
Discussion
A3 showed solubility in water (pH 7.0) of 1.0 mg/mL, which
allows the preparation of its solution in water up to 2.6 mM.
As expected, A4 showed a higher solubility in water, which
proved to be of 2.0 mg/mL (pH 7.0; up to 5.3 mM solution).
We tested the serum stability of A3 and A4 at 0.5 mM. The
results indicated that the acetate functions of A3 were partially
hydrolyzed in 15 min furnishing a mixture of diacetate derivatives
(50,20-, 50,30- and 30,20-O-diacetate) which were completely con-
verted into AICAR in the following 4 h. A4 resulted to be com-
pletely stable up to 24 h. A very small amount (2–3%) of AICAR
Diabetes and insulin resistance are important public health
conditions worldwide and their prevalence continues to increase
also in the young population1. AICAR plays a central role in the
metabolism and in signal transduction increasing insulin proper-
ties, up-regulating mitochondrial enzymes in muscles and
decreasing intra-abdominal fat2–4. It can act as an agonist and
antagonist for a number of enzymes crucial for the cell life;
among these, AMPKa has a fundamental role in energy
homeostasis, being an energy sensor implicated in various

DOI: 10.3109/14756366.2015.1063622
New AICAR derivatives with enhanced AMPK and ACC activation
5
Figure 3. Cytotoxicity of AICAR, ZMP and
A3 and A4 derivatives on A549, HepG2 and
C2C12 cell lines. (A) A549, (B) HepG2, (C)
C2C12 cells were treated with 1.0 mM
AICAR, ZMP, A3 and A4 for 24, 48 and 72 h
and viability assessed by MTT assay. Values
represent means SE of experiments per-
formed two times in triplicate. Statistical
differences between untreated cells (control)
and treated cells are indicated by * and
among cells treated with AICAR and
derivatives by x. p50.05.
metabolic diseases such as type 2 diabetes and obesity19; in the activity of the new molecules A3 and A4 was comparable to
addition, recently AMPKa has been associated with the develop- that of AICAR and ZMP. In fact, both derivatives were able to
ment of cancer and neurological disorders20.
phosphorylate both AMPKa and ACC; this phosphorylation
In this context, we have investigated the metabolic activities occurs probably via AMPKa. Consistent with our results, Rattan
of A3 and A4 newly synthesized AICAR analogs. The for- et al. have evidenced that AICAR induces a consistent increase of
mer, 20,30,50-tri-O-acetyl-AICAR (A3), contains a triacetate AMPKa and ACC phosphorylation in glioma and prostate cell
ribose moiety. This kind of modified sugar has been proposed lines22 while Kim et al. have achieved a similar result in myotube
and investigated in other nucleosides as a lipophilic pro- cells23. Given the efficacy of A3 and A4 to activate AMPKa and
ribose moiety21. The latter, AICAR derivative A4, contains a inhibit ACC, we have verified their potential cytotoxic effects on
20,30-O-4-hydroxymethyl-(1R)-benzylidene group and conserves A549, HepG2 and C2C12 cell lines. Our findings (Figure 3) have
its 50-hydroxy function free. This ribose profile leads to a indicated that the exposure of the cells to AICAR, ZMP and A3
molecule having lipophilicity that is intermediate between the and A4 (1.0 mM) up to 24 h, does not affect the cell viability.
more polar AICAR and the less polar A3. In particular, we have A decrease in cell viability occurs after 48 h (almost 50%).
verified whether A3 and A4 could exert similar or higher Consistent with our results, Peyton et al. have found that AICAR
phosphorylation activity towards AMPKa than AICAR and ZMP reduces the cell viability of endothelial cells after just 24 h and
on A549, HepG2 and C2C12 cell lines at two different Guan et al. have found similar results in CaSki cells24,25
.
concentrations (0.5 and 1.0 mM). In addition, we have evaluated Interestingly, in terms of cell proliferation, we have tested
the relationship between AMPKa phosphorylation and ACC to ERK1/2 phosphorylation: according to the MTT results, at 2 h
verify the efficacy of the treatments. Our findings have shown that of incubation, ERK1/2 phosphorylation was down regulated in

6
O. Scudiero et al.
J Enzyme Inhib Med Chem, Early Online: 1–6
8. Bracci A, Colombo G, Ronchetti F, Compostella F. 2-O-Alkyl
derivatives and 50-analogues of 5-aminoimidazole-4-carboxamide-1-
b-D-ribofuranoside (AICAR) as potential Hsp90 inhibitors. Eur J
Org Chem 2009;2009:5913–19.
9. Joshi S, Platanias LC. Mnk kinase pathway: cellular functions and
biological outcomes. World J Biol Chem 2014;5:321–33.
10. Ewart MA, Kennedy S. Diabetic cardiovascular disease AMP-
activated protein kinase (AMPK) as a therapeutic target. Cardiovasc
Hematol Agents Med Chem 2012;10:190–211.
11. D’Errico S, Oliviero G, Borbone N, et al. Synthesis of new
acadesine (AICA-riboside) analogues having acyclic D-ribityl or
4-hydroxybutyl chains in place of the ribose. Molecules 2013;18:
9420–31.
treated cells (data not shown). These findings indicate that A3 and
A4 are molecules with promising therapeutic properties for the
treatment of the metabolic disorders. Consistent with our results,
Baumann et al. in myeloma cells have found an increase on
p-AMPKa and a decrease of p-ERK1/2 phosphorylation together
with a reduction of cell viability induced by AICAR after 90 min
of treatment26. On the other hand, in contrast with our results,
Kim et al. have found that AICAR induces p-ERK1/2 phosphor-
ylation after 15 min of treatment until 60 min in osteoblastic
cell lines27.
12. Oliviero G, Amato J, Borbone N, et al. Synthesis of 4-N-alkyl and
ribose-modified AICAR analogues on solid support. Tetrahedron
2008;64:6475–81.
Conclusions
In conclusion, the need to improve therapeutic strategies against
metabolic disorders has prompted the discovery of new molecules 13. Oliviero G, Errico S, Borbone N, et al. A solid-phase approach to the
synthesis of N-1-alkyl analogues of cyclic inosine-diphosphate-
of metabolic processes able to reduce insulin resistance. In this
ribose (cIDPR). Tetrahedron 2010;66:1931–6.
study, we synthesized two novel AICAR derivatives with: (a)
14. Nigro E, Scudiero O, Sarnataro D, et al. Adiponectin affects lung
modified ribose moieties that impart to them different cell
permeability and serum stability; (b) consistent metabolic activity
epithelial A549 cell viability counteracting TNFa and I1b toxicity
through AdipoR1. Int J Biochem Cell Biol 2013;45:1145–53.
in terms of AMPK and ACC phosphorylation; (c) low-grade
15. Scudiero O, Galdiero S, Nigro E, et al. Chimeric beta-defensin
cytotoxic activity toward human and mouse cell lines.
Altogether, the two analogs could be considered as promising
potential therapeutic tools.
Further studies are needed to completely elucidate the activity
of A3 and A4 and the possibility of their use for the treatment of
metabolic disorders.
analogs, including the novel 3NI analog, display salt-resistant
antimicrobial activity and lack toxicity in human epithelial cell lines.
Antimicrob Agents Chemother 2013;57:1701–8.
16. D’Errico S, Oliviero G, Borbone N, et al. Solid-phase synthesis of a
new diphosphate 5-aminoimidazole-4-carboxamide riboside
(AICAR) derivative and studies toward cyclic AICAR diphosphate
ribose. Molecules 2011;16:8110–18.
17. Oliviero G, Amato J, Borbone N, et al. Synthesis of N-1 and ribose
modified inosine analogues on solid support. Tetrahedron Lett 2007;
48:397–400.
Declaration of interest
18. De Napoli L, Messere A, Montesarchio D, et al. 1-Substituted 20-
The authors report no conflicts of interest. The authors alone are
responsible for the content and writing of this article.
deoxyinosine analogues.
2079–82.
J Chem Soc Perkin Trans 1997;14:
19. Petti C, Vegetti C, Molla A, et al. AMPK activators inhibit the
proliferation of human melanomas bearing the activated MAPK
pathway. Melanoma Res 2012;22:341–50.
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