Design, synthesis and in vitro antitumour activity of new heteroaryl ethylenes

Article abstract of DOI:10.1016/j.ejmech.2011.10.060

Almond and VolSurf + modelling procedures allowed the structural design of new di- and mono-heteroaryl-ethylenes. The structural modifications suggested by the molecular modelling were verified by the synthesis of the designed molecules and by the evaluation of their in vitro activities against two lung tumour cell lines, A549 and H226. 2-{(E)-2-[5′-(Dibutylamino)-2,2′- bithien-5-yl]vinyl}-1-methylquinolinium iodide exhibited in vitro antiproliferative activity two orders of magnitude higher than that of the most active compound previously synthesized in our laboratory.

Full text of DOI:10.1016/j.ejmech.2011.10.060

European Journal of Medicinal Chemistry 47 (2012) 221e227
Contents lists available at SciVerse ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Design, synthesis and in vitro antitumour activity of new heteroaryl ethylenes
,
a
a
b
Cosimo G. Fortuna a , Vincenza Barresi , Carmela Bonaccorso , Giuseppe Consiglio ,
*
Salvatore Failla b, Angela Trovato-Salinaro a, Giuseppe Musumarra a
a Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale A. Doria 6 95125, Catania, Italy
b Dipartimento di Ingegneria Industriale e Meccanica, Università degli Studi di Catania, Viale A. Doria 6 95125, Catania, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
Almond and VolSurf þ modelling procedures allowed the structural design of new di- and mono-
heteroaryl-ethylenes. The structural modifications suggested by the molecular modelling were verified
by the synthesis of the designed molecules and by the evaluation of their in vitro activities against two
lung tumour cell lines, A549 and H226. 2-{(E)-2-[50-(Dibutylamino)-2,20-bithien-5-yl]vinyl}-1-
methylquinolinium iodide exhibited in vitro antiproliferative activity two orders of magnitude higher
than that of the most active compound previously synthesized in our laboratory.
Received 1 August 2011
Received in revised form
24 October 2011
Accepted 25 October 2011
Available online 11 November 2011
Ó 2011 Elsevier Masson SAS. All rights reserved.
Keywords:
Molecular modelling
Antitumour compounds
Heterocycles
QSAR
1. Introduction
Volsurf approaches. In this work, we designed some structures with
quinolinium, pyridinium and imidazolium salts linked by one or
Previous work on the design, the synthesis and the antitumour
activity of new trans 1-heteroaryl-2-(1,3-dimethylimidazolium-2-
yl) ethylenes [1] confirmed the hypothesis, based on a Molecular
Interaction Field (MIF) [2,3] approach using Grid Independent
Descriptors (GRIND) [4], that the presence of three aromatic
moieties and of halogen atoms are the main structural features
necessary to obtain satisfactory antiproliferative activities. The
synthesis, QSAR modelling using the program Almond, and bio-
logical [5e8] assays of vinyl and halo-furan derivatives has been
reported and their activities as anticancer drugs evaluated together
with their toxicity effects [9e12]. Recent work of our group on the
design of new trans 2-(furan-2-yl)vinyl heteroaromatic iodides [13]
and new trans 2-(thiophen-2-yl)vinyl heteroaromatic iodides [14]
using a new chemoinformatic tool, VolSurfþ, including both
modelling of ADME (Adsorption, Distribution, Metabolism, Elimi-
nation) properties in the design of new structures and the corre-
lation 3D molecular fields with physico-chemical and
pharmacokinetic properties, was adopted for predicting their
in vitro antitumour activities. In this context we here report the
design, the synthesis and the biological evaluation of new di- and
mono-heteroaryl-ethylenes designed using both Almond and
two ethylenic bonds to different substituted aromatic and hetero-
aromatic moieties. The structural modifications suggested by the
molecular modelling approach have been verified by the synthesis
of the designed molecules and by the evaluation of their in vitro
activities tests against two lung tumour cell lines, A549 and H226.
2. Results and discussion
The structures of the compounds reported in Scheme 1 were
first modelled selecting a MIF approach, adopting Grid Independent
Descriptors calculated using the program Almond, based on the 3D
structures following the procedure described in the Computational
Methods section.The cyano derivative 3a was inserted in Scheme 1
as phenylacrylonitriles have recently been reported to display high
levels of groeth inibition against several human cancer cell lines
[15]. Compound 1c, the most active previously synthesized in our
laboratory, was also imported for comparison.
PCA of ALMOND descriptors relative to compounds in Scheme 1
afforded a 5 PC model explaning 80.3% of variance. In Fig. 1, the
scores plot depicting the data structure elucidated by 3 PC
(explaining approximatively 70% of variance), the most active
compound (1c), exhibits a positive value in y axis, which can
reasonably be assumed as a direction representative of antitumour
activities. We can notice that compounds 1d, 2a, 2b and 2c exhibit
higher Y values, while 1a is comparable with 1c.
* Corresponding author. Fax: þ39095580138.
E-mail address: cg.fortuna@unict.it (C.G. Fortuna).
0223-5234/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.10.060

222
C.G. Fortuna et al. / European Journal of Medicinal Chemistry 47 (2012) 221e227
Scheme 1. Structures of the synthesized compounds.
Almond is based on the assumption that the process of
conditions, outlined in the experimental section, pure trans isomers
1e5 were obtained, as evidenced by the ethylenic protons J coupling
constants in the NMR spectra.
The antiproliferative activities of the newly synthesized
compounds were then tested against two tumour cell lines of
human lung carcinoma, A549 and H226. The in vitro activities,
expressed as Log GI50 values (see Experimental Section), are
recorded in Table 1, together with that of 1c, the most active
compound in previous in vitro tests. Some designed and
ligandereceptor interaction can be represented with the help of
MIF. However, an increased drugereceptor interaction does not
necessarily imply an increase in biological activity. It is also very
important to design new structures which exhibit ADME properties
warranting an acceptable bioavailability. A high-throughput che-
moinformatic approach should therefore include modelling of
ADME properties in the design of new structures. For this purpose,
the Volsurf approach, able to correlate 3D molecular structures
with physico-chemical properties, appears to be appropriate.
Therefore the same frameworks were analysed by a recent devel-
opment of this methodology called VolSurfþ. PCA for the same
compounds afforded a 5 PC model explaining 90.3% of variance. In
Fig. 2 we report 3D Volsurf PCA scores plot where it is possible to
notice a trend similar to Almond, with the same compounds
exhibiting positive values along the 1st component.
This finding implies that the designed compounds are expected
to exhibit both satisfactory activities and bio-availabilities. In this
context we decided to experimentally verify the model indications
by synthesizing and testing in vitro the designed compounds
spanning a wide range of expected activities. The synthesis of
iodides 1e5 is straightforward and can be easily achieved by
condensation of pyridinium, quinolinium or imidazolium iodides
with heteroaromatic aldehydes (Scheme 2). As expected, the
a
methyls are quite reactive due to the strong electron withdrawing
effect of the adjacent positively charged nitrogen atom.
50-(Dibutylamino)-2,20-bithiophene-5-carbaldehyde [16] was
synthesized adopting a synthetic procedure involving the direct
amidation of the 4-Oxo-4-thiophen-2-yl-butyric acid with N,N-
dibutylamine through a DCC-BtOH catalysed reaction followed by
treatment of the resulting amide with Lawesson’s reagent to give
the corresponding N,N-dibutylaminobithiophene. The aldehyde
was obtained by metallation, using n-BuLi, followed by quenching
with DMF (see Supporting Information). Under appropriate
Fig. 1. Three components Almond scores plot for compounds 1e5.

C.G. Fortuna et al. / European Journal of Medicinal Chemistry 47 (2012) 221e227
223
Table 1
In vitro antitumour activities for A549 and H226 cell lines.
Compounds/cell lines
A549a
H226a
1a
1c
1d
2a
2b
2d
3a
3b
4a
4b
ꢀ5.81
ꢀ5.70
ꢀ8.00
ꢀ6.43
ꢀ5.50
ꢀ5.32
ꢀ5.42
ꢀ4.64
ꢀ5.80
ꢀ5.78
ꢀ6.20
ꢀ5.84
ꢀ7.34
ꢀ7.35
ꢀ5.70
ꢀ6.00
ꢀ4.71
ꢀ4.00
ꢀ5.00
ꢀ4.00
a
Expressed as Log GI50
.
confirmed by the poor activity of compounds with lower Y values in
Figs. 1 and 2. These results confirm that the presence of at least
three aromatic/heteroaromatic moieties is needed to obtain good
antiproliferative activities, which can be further potentiated by
dialkylamino substituents linked to an aromatic ring.
3. Conclusion
Fig. 2. Three components VolSurf þ scores plot for compounds 1e5.
This work confirms the potentialities of Almond and
VolSurf þ modelling procedures, which allowed the structural
design of 1d and 2a exhibiting in vitro antitumour activities two
orders of magnitude higher than that of 1c, the most active
compound previously synthesized in our laboratory. Further
structural modifications of 1d, at the present the lead compound
for future studies, might produce even better in vitro antitumour
activities vs A549.
synthesized compounds in Scheme 1 are not reported in Table 1
due to their poor solubility in aqueous solution which prevented
a reliable evaluation of their in vitro activities. It is also worth
mentioning that, in order to obtain comparable biological tests, Log
GI50 were all measured in the same experiment. The percent of
growth and the inhibition exerted by different doses (0.01e100 mM)
are recorded in Figs. 3 and 4. In addition to antiproliferative effects
(Log GI50), in Table 2 cytotoxic activities, expressed as Log LC50
values, are also reported.
4. Experimental section
Experimental in vitro values in Tables 1 and 2 support the
overall picture provided by the Almond and VolSurf þ models. In
fact compounds 1d and 2a, indicated by the modelling procedures
to have a very good activity and bioavailability, are actually the
most active ones, exhibiting unprecedented Log GI50 (up to ꢀ8 vs
A549) values and good citotoxycities. The validity of the models is
4.1. Computational Methods
4.1.1. VolSurf þ descriptors
The interaction of molecules with biological membranes is
mediated by surface properties such as shape, electrostatic forces,
H-bonds and hydrophobicity. Therefore, the GRID force field was
chosen to characterize potential polar and hydrophobic interaction
sites around target molecules by the water (OH2), the hydrophobic
(DRY), and the carbonyl oxygen (O) and amide nitrogen (N1) probe.
The information contained in the MIF is transformed into a quan-
titative scale by calculating the volume or the surface of the inter-
action contours. The VolSurf þ procedure is as follows: i) in the first
step, the 3D molecular field is generated from the interactions of
the OH2, the DRY, O and N1 probe around a target molecule; ii) the
second step consists in the calculation of descriptors from the 3D
Scheme 2. General procedures for synthesis of compounds 1e5 (see Scheme 1 for R).
Fig. 3. Dose e response curves of antiproliferative activities vs A549.

224
C.G. Fortuna et al. / European Journal of Medicinal Chemistry 47 (2012) 221e227
whichismoved througha regular gridof pointsin aregionofinterest
around the targetmolecule and, ateach point, the interaction energy
between the probe and the target molecule is calculated as the sum
of Lennard-Jones (ELJ), hydrogen bond (EHB) electrostatic interac-
tions (EEL) and, for specific probes, entropic contribution (EENT):
N
N
N
X
X
X
Exx;y;z
¼
EL J
þ
EHB
þ
EENT
i ¼ 1
i ¼ 1
i ¼ 1
GRID contains a table of parameters to describe each type of
atom occurring in each of the ligand molecules. These parameters
define the strength of the Lennard-Jones, hydrogen bond and
electrostatic interactions made by an atom and are used in order to
evaluate the energy functions. GRID probes are very specific. They
give precise spatial information, and this specificity and sensitivity
are an advantage since the probes may then be representative of
the important chemical groups present in the active site provided
that the statistical method used for the analysis can distinguish
between different types of interactions.
Fig. 4. Dose e response curves of antiproliferative activities vs H226.
maps obtained in the first step. The molecular descriptors obtained,
called VolSurf þ descriptors, refer to molecular size and shape, to
hydrophilic and hydrophobic regions and to the balance between
them, to molecular diffusion, LogP, LogD, to the “charge state”
descriptors, to the new 3D pharmacophoric descriptors and to
some descriptors on some rilevant ADME properties [17e20].
Finally, chemometric tools (PCA [21], PLS [22]) are used to create
relationships of the VolSurf þ descriptor matrix with ADME prop-
erties. The scheme of the VolSurf þ programme steps and a detailed
definition of Volsurf þ descriptors have recently been reported [14].
4.2. Synthesis
4.2.1. General
All the chemicals were obtained from Sigma Aldrich and used as
received. Thin layer chromatography (TLC) was carried out on silica
gel plates (Merck 60, F254). All reactions were carried out under
nitrogen atmosphere unless otherwise stated. NMR experiments
were carried out at 27 ꢁC on a 500 MHz spectrometer (1H at
499.88 MHz, 13C NMR at 125.7 MHz) equipped with a pulse field
gradient module (Z axis) and a tunable 5 mm Varian inverse
4.1.2. Almond
MIF were obtained using the program GRID version 2.0 [23].
GRIND were generated, analysed, and interpreted using the program
Almond version 3.0.0 [24], a software package developed in our
group. Computations and graphical display were performed on SGI
O2 workstations (MIPS R12000 processor). The process of
ligandereceptor interaction has often been represented with the
help of the MIF. If a compound is known to bind a certain receptor,
some of the regions defined in its Virtual Receptor Site (VRS) [4]
should actually overlap groups of the real receptor site and, there-
fore, at least a subset of the VRS regions would be relevant for rep-
resenting the binding properties of the ligand. For the latter
statement to be true the VRS must have been obtained from the
bioactive conformation of the ligand and the probes used to
compute it should represent chemical groups present in the binding
site. The molecular descriptors presented in this work are based on
the concept of VRS. Basically, GRIND are a small set of variables
representing the geometrical relationships between relevant
regions of the VRS and as such are independent of the coordinate
frame of the space where the MIF is computed. The procedure for
obtaining GRIND involves three steps: (i)computing a set of MIF, (ii)
filtering the MIF to extract the most relevant regions that define the
VRS, and (iii)encoding the VRS into the GRIND variables.
detection probe (ID-PFG); chemical shifts (d) are expressed in ppm
and are referenced to residual undeuterated solvent. NMR data were
processed using the MestReC software. Electrospray ionization mass
spectra (ESI-MS) were recorded on a Finnigan LCQ Deca XP ion trap
(Thermo Fischer Scientific, USA) using an electrospray ionization
(ESI) interface. Melting points are uncorrected. 2-(Pyridin-2-yl)
acetonitrile, 4-(dimethylamino)benzaldehyde, 5-chlorothiophene-
2-carbaldehyde, 2,20-bithiophene-5-carbaldehyde, 1-methyl-1H-
pyrrole-2-carbaldehyde and 1-methyl-1H-indole-2-carbaldehyde
were Aldrich commercial products. 50-(Dibutylamino)-2,20-bithio-
phene-5-carbaldehyde [16], 4-(diphenylamino)-benzaldehyde [27],
1,2-dimethylquinolinium iodide [28], 1,2,6-trimethylpyridinium
iodide [29], 1,2-dimethyl-picolinium iodide [30], 1,4-dimethyl-
picolinium iodide [31] and 1,2,3-trimethylimidazolium iodide [32]
were prepared according to the literature.
4.3. General procedure for the synthesis of compounds 1e5
Compounds 1e5, all iodide salts, were obtained by refluxing in
ethanol stoichiometric amounts (see Scheme 2) of 1,2-
dimethylquinolinium iodide, 1,2,6-trimethylpyridinium iodide, 1,2-
dimethyl-picolinium iodide, 1,4-dimethyl-picolinium iodide or
1,2,3-trimethylimidazolium iodide and the appropriate aldehyde in
the presence of catalytic amount of piperidine. The resulting
precipitates wererecrystallizedfrom ethanol.Details onthesynthetic
conditions and products characterization are reported below.
4.1.3. Molecular description: GRID Force Field
The GRID program [2,25,26] was used to describe the molecular
structures. GRID is a computational procedure for detecting ener-
getically favourable binding sites on molecules. The program
calculates the interactions between the molecule and a probe group
Table 2
In vitro antitumour activities for A549 and H226 cell lines.
4.3.1. 2-(Cyanomethyl)-1-methylpyridinium iodide
Compounds/cell lines
A549a
H226a
2-(Pyridin-2-yl)acetonitrile (1.180 g, 10.00 mmol), and iodo-
methane (4.26 g, 30.00 mmol) were dissolved in acetonitrile (5 mL),
and stirred for 24 h at room temperature. The solid precipitated was
collected by filtration and washed with cold acetonitrile to gave 2-
(cyanomethyl)-1-methylpyridinium iodide as pale-brown needles
(1.846 g. 71%): m.p.: 205e207 ꢁC; 1H NMR (500 MHz [D6]DMSO):
1a
1c
1d
2a
2b
ꢀ4.15
e
ꢀ4.20
ꢀ4.42
ꢀ5.00
ꢀ4.86
ꢀ4.48
e
ꢀ4.88
ꢀ4.40
a
Expressed as Log LC50
.

C.G. Fortuna et al. / European Journal of Medicinal Chemistry 47 (2012) 221e227
225
d
¼ 4.26 (s, 3H, NþCH3), 4.79 (s, 2H, CH2CN), 8.11 (t, J ¼ 7.0 Hz, 1H,
4.3.8. 2,6-Bis[(E)-2-(2,20-bithien-5-yl)vinyl]-1-methylpyridinium
iodide, 2c
The compound was synthesized according to the general
procedure using 1,2,6-trimethylpyridinium iodide (0.100 g,
0.40 mmol) and 2,20-bithiophene-5-carbaldehyde (0.155 g,
0.80 mmol) to gave 2c as orange needles (0.053 g, 21%);
ArH), 8.17 (d, J ¼ 7.0 Hz,1H, ArH), 8.63 (t, J ¼ 7.5 Hz,1H, ArH), 9.07 (d,
J ¼ 6.0 Hz, 1H, ArH); 13C NMR (126 MHz [D6]DMSO):
d
¼ 46.96,
106.41, 126.58, 130.35,134.26,145.54,146.82 ppm; MS (positive ESI)
m/z (%): 134 (100) [M ꢀ I]þ.
4.3.2. 2-{(E)-2-[4-(Dimethylamino)phenyl]vinyl}-1-methylquinoli-
nium iodide [33], 1a
The compound was synthesized according to the general
procedure using 1,2-dimethylquinolinium iodide (0.570 g, 2 mmol)
and 4-(dimethylamino)benzaldehyde (0.298 g, 2.00 mmol) to gave
1a (0.691 g, 83%).
m.p.:192e195 ꢁC; 1H NMR (500 MHz [D6]DMSO):
d
¼ 4.23 (s, 3 H,
NþCH3), 7.16 (d, J ¼ 4.0 Hz, 2H, ArH), 7.30 (d, J ¼ 15.5 Hz, 2H, CH]
CH), 7.43 (d, J ¼ 3.5 Hz, 2H, ArH), 7.47 (d, J ¼ 3.5 Hz, 2H, ArH), 7.59 (d,
J ¼ 4.0 Hz, 2H, ArH), 7.63 (d, J ¼ 5.0 Hz, 2H, ArH), 7.96 (d, J ¼ 15.5 Hz,
2H, CH]CH), 8.20 (d, J ¼ 8.0 Hz, 2H, ArH), 8.37 (t, J ¼ 8.0 Hz, 1H,
ArH) ppm; 13C NMR (126 MHz, CDCl3):
122.56, 124.39, 124.94, 128.04, 131.12, 134.70, 137.35, 138.68, 139.71,
d
¼ 44.52, 120.92, 122.48,
4.3.3. 2-[(E)-2-(5-Chloro-2-thienyl)vinyl]-1-methylquinolinium
iodide, 1b
142.12, 158.61 ppm; MS (positive ESI): m/z (%): 474.2 [M ꢀ I]þ.
The compound was synthesized according to the general
procedure using 1,2-dimethylquinolinium iodide (0.150 g,
0.53 mmol) and 5-chlorothiophene-2-carbaldehyde (0.077 g,
0.53 mmol) to gave 1b as brown needles (0.088 g. 40%);
4.3.9. 2,6-Bis-{(E)-2-[50-dibutylamino-2,20-bithienyl-5-yl]-vinyl}-
1-methylpyridinium iodide, 2d
The compound was synthesized according to the general
procedure using 1,2,6-trimethylpyridinium iodide (0.025 g,
0.1 mmol) and 50-(dibutylamino)-2,20-bithiophene-5-carbaldehyde
(0.074 g, 0.2 mmol) to gave 2d as dark oil (0.055 g, 65%); 1H NMR
m.p.:189e191 ꢁC; 1H NMR (500 MHz [D6]DMSO):
d
¼ 4.48 (s, 3H,
NþCH3), 6.54 (d, J ¼ 3.5 Hz, 1H, ArH), 7.50 (d, J ¼ 16.0 Hz, 1H, CH]
CH), 7.14 (d, J ¼ 3.5 Hz, 1H, ArH), 7.93 (t, J ¼ 8.0 Hz, 1H, ArH), 8.17 (t,
J ¼ 7.0 Hz, 1H, ArH), 8.30 (d, J ¼ 16.0 Hz, 1H, CH]CH), 8.31 (d,
J ¼ 7.0 Hz, 1H, ArH), 8.44 (d, J ¼ 9.0 Hz, 1H, ArH), 8.56 (d, J ¼ 9.0 Hz,
1H, ArH), 9.01 (d, J ¼ 9.0 Hz, 1H, ArH) ppm; 13C NMR (126 MHz [D6]
(500 MHz, CDCl3):
d
¼ 0.97 (t, J ¼ 7.4 Hz, 12H, eCH3); 1.36 (m, 8H,
CH2); 1.61 (m, 8H, CH2); 3.21 (t, J ¼ 7.4 Hz, 8H, NCH2); 4.25 (s, 3H,
NþCH3), 5.72 (d, J ¼ 3.3 Hz, 2H, ArH), 6.71 (d, J ¼ 3.3 Hz, 2H, ArH),
6.73 (d, J ¼ 15.5 Hz, 2H, CH]CH), 7.01 (d, J ¼ 4.0 Hz, 2H, ArH), 7.33
(d, J ¼ 4.0 Hz, 2H, ArH), 7.68 (d, J ¼ 15.5 Hz, 2H, CH]CH), 7.90 (d,
J ¼ 7.8 Hz, 2H, ArH), 7.98 (t, J ¼ 7.8 Hz, 1 H, ArH) ppm; 13C NMR
DMSO):
d
¼ 45.15, 119.42, 122.67, 122.91; 122.96; 124.72; 124.79;
126.06; 127.92; 133.21; 135.53; 137.55; 140.58; 140.65; 141.07;
151.57 ppm; MS (positive ESI): m/z (%): 286.2 [M ꢀ I]þ.
(126 MHz [D6]DMSO):
d
¼ 13.91, 20.24, 29.17, 42.71, 53.36, 101.70,
113.17, 117.99, 120.42, 121.76, 127.02, 134.87, 135.15, 135.42, 141.19,
144.70, 152.62, 159.13 ppm; MS (positive ESI): m/z (%): 729.0
[M ꢀ I]þ.
4.3.4. 1-methyl-2-[(E)-2-(5-Phenyl-2-thienyl)vinyl]quinolinium
iodide [14], 1c
The compound was synthesized according to the general
procedure using 1,2-dimethylquinolinium iodide (0.200 g,
0.70 mmol) and 5-phenylthiophene-2-carbaldehyde to gave 1c
(0.061 g. 30%).
4.3.10. 2-[(Z)-2-(4-Aminophenyl)-1-cyanovinyl]-1-
methylpyridinium iodide, 3a
The compound was synthesized according to the general
procedure using 2-(cyanomethyl)-1-methylpyridinium iodide
(0.520 g, 2 mmol) and 4-(dimethylamino)benzaldehyde (0.298 g,
2.00 mmol) to gave 3a as green-grey needles (0.626 g, 80%); m.p.:
4.3.5. 2-{(E)-2-[5’-(Dibutylamino)-2,20-bithien-5-yl]vinyl}-1-
methylquinolinium iodide [16], 1d
The compound was synthesized according to the general
procedure using 1,2-dimethylquinolinium iodide (0.057 g,
0.2 mmol) and 50-(dibutylamino)-2,20-bithiophene-5-carbaldehyde
(0.074 g, 0.2 mmol) to gave 1d (0.054 g, 41%).
183e185 ꢁC dec.; 1H NMR (500 MHz [D6]DMSO):
d
¼ 3.10 (s, 6 H,
ArNCH3), 4.36 (s, 3H, NþCH3), 6.89 (d, J ¼ 9.0 Hz, 2H, ArH), 7.80 (s,
1H, CH]C), 7.95 (d, J ¼ 9.0 Hz, 2H, ArH), 8.08 (t, J ¼ 6.5 Hz, 1H, ArH),
8.25 (d, J ¼ 8.0 Hz, 1H, ArH), 8.61 (t, J ¼ 8.0 Hz, 1H, ArH), 9.04 (d,
J ¼ 6.5 Hz, 1H, ArH) ppm; 13C NMR (126 MHz [D6]DMSO):
4.3.6. 2,6-Bis{(E)-2-[4-(Dimethylamino)phenyl]vinyl}-1-
methylpyridinium iodide [34], 2a
The compound was synthesized according to the general
procedure using 1,2,6-trimethylpyridinium iodide (0.248 g,
1.00 mmol) and 4-(dimethylamino)-benzaldehyde (0.298 g,
2.00 mmol) to gave 2a (0.307 g. 60%).
d
¼ 155.47, 153.97, 150.98, 147.81, 146.17, 133.53, 130.31, 127.05,
119.62,117.56,112.19, 91.43, 47.39, 40.16 ppm; MS (positive ESI): m/z
(%): 265.3 [M ꢀ I]þ.
4.3.11. 1-Methyl-2-[(E)-2-(1-methyl-1H-pyrrol-2-yl)vinyl]
pyridinium iodide [35], 3b
The compound was synthesized according to the general
procedure using 1,2-dimethylpyridinium iodide (0.470 g, 2 mmol)
and 1-methyl-1H-pyrrole-2-carbaldehyde (0.218 g, 2.00 mmol) to
gave 3b (0.639 g, 98%).
4.3.7. 2,6-Bis{(E)-2-[4-(diphenylamino)phenyl]vinyl}-1-
methylpyridinium iodide, 2b
The compound was synthesized according to the general
procedure using 1,2,6-trimethylpyridinium iodide (0.248 g,
1.00 mmol) and 4-(diphenylamino)benzaldehyde (0.545 g,
2.00 mmol), to gave 2b as red needles (0.600 g. 79%);
4.3.12. 1-Methyl-2-[(E)-2-(1-methyl-1H-indol-2-yl)vinyl]
pyridinium iodide, 3c
m.p.:230e233 ꢁC; 1H NMR (500 MHz [D6]DMSO):
d
¼ 4.23 (s, 3H,
The compound was synthesized according to the general
procedure using 1,2-dimethylpyridinium iodide (0.100 g,
0.043 mmol) and 1-methyl-1H-indole-2-carbaldehyde (0.065 g,
0.043 mmol) to gave 3c as orange needles (0.062 g, 39%) m.p.:
NþCH3), 6.96 (d, J ¼ 8.5 Hz, 4H, ArH), 7.11 (d, J ¼ 7.0 Hz, 8H, ArH), 7.16
(t, J ¼ 7.0 Hz, 4H, ArH), 7.38 (t, J ¼ 7.0 Hz, 8H, ArH), 7.46 (d,
J ¼ 16.0 Hz, 2H, CH]CH), 7.69 (d, J ¼ 16.0 Hz, 2H, CH]CH), 7.72 (d,
J ¼ 8.5 Hz, 4H, ArH), 8.18 (d, J ¼ 8.5 Hz, 2H, ArH), 8.33 (t, J ¼ 8.5 Hz,
183e185 ꢁC dec.; 1H NMR (500 MHz [D6]DMSO):
d
¼ 3.30 (s, 3H,
1H, ArH) ppm; 13C NMR (126 MHz [D6]DMSO):
d
¼ 153.88, 149.86,
NCH3), 3.95 (s, 3H, NþCH3), 7.09 (m, 1H, ArH); 7.26 (d, J ¼ 15.5 Hz,
1H, CH]CH); 7.26 (m, 1H, ArH), 7.45 (s, 1H, ArH), 7.54 (d, J ¼ 8.5 Hz,
1H, ArH), 7.63 (d, J ¼ 7.5 Hz, 1H, ArH), 7.86 (m, 1H, ArH), 8.12 (d,
J ¼ 15.5 Hz, 1H, CH]CH); 8.48 (t, J ¼ 8.0 Hz, 1H, ArH), 8.70 (d,
146.75, 142.85, 142.32, 130.43, 130.28, 128.65, 125.66, 124.85,
123.28, 121.40, 116.88, 41.91ppm; MS (positive ESI): m/z (%): 632.9
[M ꢀ I]þ.

226
C.G. Fortuna et al. / European Journal of Medicinal Chemistry 47 (2012) 221e227
J ¼ 7.5 Hz, 1H, ArH), 8.87 (t, J ¼ 8.0 Hz, 1H, ArH) ppm; 13C NMR
test compound; T0 is the optical density at time zero; C is the DMSO
control optical density). The cytotoxicity effect was calculated
according to NCI when the optical density of treated cells was lower
than the T0 value using the following formula: 100 ꢂ (T-T0)/T0 < 0.
(126 MHz [D6]DMSO):
d
¼ 29.88, 47.79; 100.75, 109.13, 119.7,
120.44, 121.62, 122.02, 125.76, 127.38, 129.56, 131.21, 133.11, 136.34,
137.98, 145.87, 152.09 ppm; MS (positive ESI): m/z (%): 249.3
[M ꢀ I]þ.
Acknowledgements
4.3.13. 4-{(E)-2-[4-(Dimethylamino)phenyl]vinyl}-1-
methylpyridinium iodide [36], 4a
The compound was synthesized according to the general
procedure using 1,4-dimethylpyridinium iodide (0.470 g, 2 mmol)
and 4-(dimethylamino)benzaldehyde (0.298 g, 2.00 mmol) to gave
4a (0.513 g, 70%).
We thank the University of Catania for financial support.
Appendix. Supplementary information
Supplementary data related to this article can be found online at
doi:10.1016/j.ejmech.2011.10.060.
4.3.14. 1-Methyl-4-[(E)-2-(1-methyl-1H-pyrrol-2-yl)vinyl]
pyridinium iodide [37], 4b
The compound was synthesized according to the general
procedure using 1,4-dimethylpyridinium iodide (0.470 g, 2 mmol)
and 1-methyl-1H-pyrrole-2-carbaldehyde (0.218 g, 2.00 mmol) to
gave 4b (0.626 g, 96%).
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d
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C.G. Fortuna et al. / European Journal of Medicinal Chemistry 47 (2012) 221e227
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