Dapson in heterocyclic chemistry part VI: Synthesis and molecular docking of some novel sulfonebiscompounds of expected anticancer activity

Article abstract of DOI:10.1055/s-0032-1323660

To discover new bioactive lead compounds for medicinal purposes, herein, sulfone biscompounds bearing dihydrothiazoles (3-9, 14, 15), acrylamide (11), thiazolidinones (12, 13, 20), thiophenes (16, 17) and benzothiophene (19) were prepared and tested for t

Full text of DOI:10.1055/s-0032-1323660

Original Article 497
Dapson in Heterocyclic Chemistry Part VI:
Synthesis and Molecular Docking of Some Novel
Sulfonebiscompounds of Expected Anticancer Activity
Authors
M. M. Ghorab1, M. S. Al-Said1, Y. M. Nissan2
Affiliations
1 Medicinal, Aromatic and Poisonous Plants Research Center (MAPPRC), College of Pharmacy, King Saud University,
Riyadh, Saudi Arabia
2 Pharmaceutical Chemistry Department, Faculty of Pharmacy, Cairo University
Key words
Abstract
All the synthesized compounds showed remark-
able anticancer activity against human breast
cancer cell line especially, compound (3) with
IC50 value 23.02μM which was better than that
of Doxorubicin by three folds. In order to eluci-
date the mechanism of action of their cytotoxic
activity molecular docking on the active sites of
farnesyl transferase and arginine methyl trans-
ferase was performed for all synthesized com-
pounds and good results were obtained.
▶
thiazole
acrylamide
thiophene
●
▼
▶
●
To discover new bioactive lead compounds for
medicinal purposes, herein, sulfone biscom-
pounds bearing dihydrothiazoles (3–9, 14, 15),
acrylamide (11), thiazolidinones (12, 13, 20), thi-
ophenes (16, 17) and benzothiophene (19) were
prepared and tested for their anticancer activity.
The structures of the products were confirmed
from elemental analysis as well as spectral data.
▶
●
▶
benzothiophene
anticancer activity
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▶
●
Introduction
nts to form a variety of heterocyclic compounds.
Also, the active methylene of cyanoacetamide
can take part in a variety of condensation and
substitution reactions. Moreover, cyanoaceta-
mides and their related heterocyclic derivatives
have generated great attention due to their
interesting biological, therapeutic value and
pharmaceutical activities such as anticancer
agents [24].
▼
Diarylsulfones is a class of compounds which
have received an interest as biologically active
agents especially in anticancer and antiviral
activities [1–6]. The diarylsulfone derivative I
showed good activity as anti HIV-1compared to
▶
Nevirapine [7,8] ( Fig. 1). Moreover, Allanto-
●
received 26.06.2012
accepted 23.07.2012
daopsone II, a diarylsulfone derivative exhibited
a remarkable anticancer effect as arginine methyl
Therefore, it was aimed in the present investiga-
tion and as a continuation to a previous work
[25–28] to synthesize and characterize a new
series of biologically active sulfone derivatives
carrying the corresponding dihydrothiazole, acr-
ylamide, acetamide, thiophene and benzothi-
ophene derivative to evaluate their anticancer
activity.
Bibliography
▶
transferase inhibitor [9] ( Fig. 1). In addition,
●
DOI http://dx.doi.org/
10.1055/s-0032-1323660
Published online:
September 21, 2012
Arzneimittelforschung 2012;
62: 497–507
© Georg Thieme Verlag KG
Stuttgart · New York
ISSN 0004-4172
thiophene and thiazole derivatives are known
to possess interesting biological properties that
showed anticancer [10–12], and antimicrobial
activities [13,14].
Thiazole derivatives constituting sulfone have
shown activity as anticancer moiety [15,16].
Compound III showed a good α-pyrolyl hydroxy-
lase inhibiton with IC50 value 0.072μM [15] while,
compound IV exhibited its activity through p13
Materials and Methods
Correspondence
▶
kinase p11α inhibition [16] ( Fig. 1). In addi-
●
▼
Prof. M. M. Ghorab
Medicinal, Aromatic and
Poisonous Plants Research
Centre (MAPPRC)
College of Pharmacy
King Saud University
P.O.Box 2457
Riyadh 11451
Saudi Arabia
Tel.: +966/53/4292 860
Fax: +966/01/4670 560
mmsghorab@yahoo.com
tion, the chemistry of acrylamide, acetamide,
thiophene and benzothiophene system has
received an increasing interest because of its bio-
logical significance. Many derivatives of this sys-
tem showed anti- inflammatory, antibacterial
[17], antifungal [18] and anticancer activities
[19–23]. On the other hand, cyanoacetamides are
highly reactive compounds. The carbonyl and the
cyano functions of these compounds are suitably
situated to enable reaction with common reage-
Chemistry
General methods
All chemicals used in this study were purchased
from Aldrich and Fluka. Melting points (°C,
uncorrected) were determined in open capillar-
ies on a Gallenkemp melting point apparatus
(Sanyo Gallenkemp, Southborough, UK) and were
uncorrected. Precoated silica gel plates (silica gel
0.25mm, 60G F254; Merck, Germany) were used
for thin layer chromatography, dichloromethane/
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

498 Original Article
(3.82g, 0.01mol.), followed by phenyl isothiocyanate (2.7g,
0.02mol.), were added. The mixture was stirred at room tem-
perature for 12h, then cooled again to 0°C, treated with chloro-
acetyl chloride (2.26g, 0.02mol.), and left to stand at room
temperature for 24h. The reaction mixture was poured into ice
water. The obtained solid was crystallized from DMF/EtOH to
give compound 12.
O
O
Cl
O
O
O
N
S
O
S
O
N
O
NH
HN
HN
NH
O
O
I
II
Cl
OH
N
N
General procedure for synthesis of compounds (13–15): T o
compound 11 (6.53g, 0.01mol.) in DMF (30mL) and ethyl chlo-
roacetate (1.45g, 0.02mol.) or chloroacetone (1.84g, 0.02mol.)
or phenacyl chloride (3.08g, 0.02mol.) was added. The reaction
mixture was heated under reflux for 6h, then cooled and neu-
tralized with saturated sodium acetate solution. The resulting
precipitate was filtered off, dried and crystallized from dioxane
to give compound 13–15, respectively.
O
N
O
S
N
OH
O
S
N
N
S
O
S
O
O
O
CH
III
IV
Fig. 1 Biologically active diarylsulfone derivatives.
methanol (9.5:0.5) mixture was used as a developing solvent
system and the spots were visualized by ultraviolet light and/or
iodine. Infra red spectra were recorded in KBr discs using IR-470
Shimadzu spectrometer (Shimadzu, Tokyo, Japan). NMR spectra
(in DMSO-d6) were recorded on Bruker AC-300 Ultra Shield
NMR spectrometer (Bruker, Flawil, Switzerland, δ ppm) at
300MHz using TMS as internal Standard and peak multiplicities
are designed as follows: s, singlet; d, doublet; t, triplet; m, mul-
tiplet. Elemental analyses were performed on Carlo Erba 1108
Elemental Analyzer (Heraeus, Hanau, Germany). All analyses
were done in Medicinal, Aromatic and Poisonous Plants Research
Center (MAPPRC), College of Pharmacy, King Saud University,
Riyadh, Saudi Arabia.
General procedure for synthesis of compounds (16 and
17): To compound 11 (6.53g, 0.01mol.) in DMF (30mL), chlo-
roacetone (1.84g, 0.02mol.) or phenacyl chloride (3.08g,
0.02mol.) and triethylamine (0.5mL) were added. The reaction
mixture was refluxed for 9h, then cooled and neutralized with
saturated sodium acetate solution. The solid obtained was crys-
tallized from dioxane to give 16 and 17, respectively.
(4,4′-sulfonylbis(4,1-phenylene))bis(2-amino-4,5,6,7-tetrahy-
drobenzo [b]thiophene-3-carboxamide) (Compound 19): T o
compound 2 (3.82g, 0.01mol.) in absolute ethanol (50mL), mor-
pholine (1.74g, 0.02mol.), cyclohexanone (1.96g, 0.02mol.), and
sulfur (0.64g, 0.02mol.) were added. The reaction mixture was
refluxed for 6h. The obtained solid was crystallized from diox-
ane to give 19.
Synthesis
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyanoacetamid)
(Compound 2): A mixture of Dapson 1 (2.48g, 0.01mol.) was
fused with excess ethyl cyanoacetate (10mL) at 220°C in an oil
bath for 2h. Excess ethyl cyanoacetate was evaporated under
vacuum. The solid product remained was triturated with dieth-
ylether (100mL) then filtered. The solid obtained was crystal-
lized from ethanol to give 2.
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-(4-oxothi-
azolidin-2-ylidene)acetamide) (Compound 20): A mixture of
compound 2 (3.82g, 0.01mol.) and 2-sulfanylacetic acid (1.84g,
0.02mol.) in acetic acid (50mL) was refluxed for 12h. The
obtained solid was crystallized from ethanol to give 20.
Molecular docking
General procedure for synthesis of compounds (3–9): T o a
suspension of compound 2 (3.82g, 0.01mol.) in ethanol (50mL),
finally divided sulfur (0.64g, 0.02mol.), triethylamine (5 drops),
isothiocyanate derivatives (0.02mol.) and dimethylformamide
(10mL) were added. The reaction mixture was stirred at 60°C
for 6h, then left to cool at room temperature. The separated
products were filtered, washed with ethanol, dried and crystal-
lized from dioxane to give 3–9, respectively.
All the molecular modeling studies were carried out on an Intel
Pentium 1.6GHz processor, 512 MB memory with Windows XP
operating system using Molecular Operating Environment
(MOE, 10.2008) software. All the minimizations were performed
with MOE until a RMSD gradient of 0.05kcal mol−1A°−1 with
MMFF94X forcefield and the partial charges were automatically
calculated. The X-ray crystallographic structure of franesyl
transferase and arginine methyl transferase (PRMT1) complexes
with their ligands (PDB ID: 3E3O, 3Q7E) were obtained from the
protein data bank. The enzymes were prepared for docking stud-
ies where: (i) Ligand molecule was removed from the enzyme
active site. (ii) Hydrogen atoms were added to the structure with
their standard geometry. (iii) MOE Alpha Site Finder was used for
the active sites search in the enzyme structure and dummy
atoms were created from the obtained alpha spheres. (iv) The
obtained model was then used in predicting the ligand enzymes
interactions at the active site.
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyano-3-
mercapto-3-(phenylamino)acrylamide) (Compound 11): T o a
cold suspension of finally divided KOH (1.12g, 0.02mol.) in dry
DMF (20mL), the cyanoacetamide derivative 2 (3.82g, 0.01mol.),
followed by phenyl isothiocyanate (2.7g, 0.02mol.), were added.
The mixture was stirred at room temperature over night then
poured into ice-water and acidified with 0.1N HCl to a pH 3–4.
The resulting precipitate was filtered off, dried and crystallized
from aqueous ethanol to give compound 11.
Biological screening
In vitro antitumor activity
Human tumor breast cell line (MCF7) was used in this study. The
cytotoxic activity was measured in vitro for the newly synthe-
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyano-2-
(5-oxo-3-phenylthiazolidin-2-ylidene)acetamide) (Compound
12): To a cold suspension of finally divided KOH (1.12g,
0.02mol.) in dry DMF (50mL), the cyanoacetamide derivative 2
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

Original Article 499
sized compounds using the Sulfo-Rhodamine-B stain (SRB)
assay using the method of Skehan et al. [29]. The in vitro anti-
cancer screening was done by the pharmacology unit at the
National Cancer Institute, Cairo University.
3483, 3380, 3371 (NH, NH2), 1680 (2 C=O), 1249 (2 C=S),
1400, 1145 (SO2). 1H-NMR (DMSO-d6, D2O): δ 3.8 (s, 6H, 2
OCH3), 6.6 (s, 4H, 2NH2, exch.), 6.8–7.8 (m, 16H, Ar-H), 10.9 (s,
2H, 2 NH, exch.). 13C-NMR (DMSO-d6): 55.1 (2), 87.8 (2), 113.8
(4), 123.3 (4), 124.4 (2), 125.3 (4), 129.7 (4), 130.1 (2), 143.1 (2),
155.9 (2), 158.3 (2), 162.2 (2), 189.3 (2). Anal.Calcd. for
Cells were plated in 96-multiwell plate (104cells/well) for 24h
before treatment with the compound(s) to allow attachment of
cell to the wall of the plate. Test compounds were dissolved in
dimethylsulfoxide. Different concentrations of the compound
under test (10, 25, 50, and 100μM) were added to the cell mon-
olayer. Triplicate wells were prepared for each individual
concentration. Monolayer cells were incubated with the
compound(s) for 48h at 37°C and in atmosphere of 5% CO2. After
48h, cells were fixed, washed and stained for 30min with 0.4%
(wt/vol) SRB dissolved in 1% acetic acid. Excess unbound dye
was removed by 4 washes with 1% acetic acid and attached stain
was recovered with Trise-EDTA buffer. Color intensity was meas-
ured in an ELISA reader. The relation between surviving fraction
and drug concentration is plotted to get the survival curve for
breast tumor cell line after the specified time. The molar concen-
tration required for 50% inhibition of cell viability (IC50) was
calculated and compared to the reference drug Doxorubicin
(CAS, 25316-40-9). The surviving fractions were expressed as
means±standard error.
C34H28N6O6S5 (776.94): C, 52.56; H, 3.63; N, 10.82. Found: C,
52.34; H, 3.86; N, 10.57.
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(4-amino-3-(4-
nitrophenyl)-2-thioxo-2,3-dihydrothiazole-5-carboxamide)
(Compound 6): Yield 71%, m.p. 165.1°C. IR:υmax./cm−1 3480,
3310, 3290 (NH, NH2), 3090 (CH arom.), 1660 (2 C=O), 1203 (2
1
C=S), 1377, 1149 (SO2). H-NMR (DMSO-d6, D2O): δ 4.5 (s, 4H,
2NH2, exch.), 6.6–8.1 (m, 16H, Ar-H), 11.6 (s, 2H, 2 NH, exch.).
13C-NMR (DMSO-d6, D2O): 67.1 (2), 123.8 (4), 124.6 (4), 126.3
(4), 128.4 (4), 129.2 (2), 142.9 (2), 144.0 (2), 145.1 (2), 161.3 (2),
162.2(2), 187.6 (2). Anal.Calcd. for C32H22N8O8S5 (806.89): C,
47.63; H, 2.75; N, 13.89. Found: C, 47.89; H, 3.11; N, 13.50.
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(4-amino-3-(4-
chlorophenyl)-2-thioxo-2,3-dihydrothiazole-5-carboxamide)
(Compound 7): Yield 91%, m.p. 122.7°C. IR:υmax./cm−1 3464,
3236, 3109 (NH, NH2), 3051 (CH arom.), 1654 (2 C=O), 1280 (2
C=S), 1377, 1145 (SO2), 821 (C-Cl). 1H-NMR (DMSO-d6, D2O): δ
4.5 (s, 4H, 2NH2, exch.), 6.6–7.9 (m, 16H, Ar-H), 11.1 (s, 2H, 2 NH,
exch.). 13C-NMR (DMSO-d6): 67.3 (2), 123.0 (4), 124.2 (4), 125.8
(4), 128.5 (4), 129.2 (4), 136.0 (2), 137.4 (2), 138.4 (2), 153.2 (2),
162.2 (2), 187.6 (2). Anal.Calcd. for C32H22Cl2N6O4S5 (785.79): C,
48.91; H, 2.82; N, 10.70. Found: C, 49.02; H, 2.56; N, 10.99.
Results
▼
Chemistry
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyanoacetamid)
(Compound 2): Yield 92%, m.p. 137.5°C. IR: υmax./cm−1 3448,
3363 (2NH), 3062 (CH arom.), 2960, 2931 (CH aliph.), 2256
(C≡N), 1701 ( 2 C=O),1342, 1180 (SO2). 1H-NMR (DMSO-d6,
D2O): δ 4.0 (s, 4H, 2CH2), 7.4–7.9 (m, 8H, Ar-H), 10.7 (s, 2H, 2NH
exchangeable). 13C-NMR (DMSO-d6): 24.4(2), 115.6(2), 119.2(2),
119.3(2), 128.1(2), 129.2(2), 137.8(2), 142.7(2), 162.2(2). Anal.
Calcd. for C18H14N4O4S (382.39): C, 56.54; H, 3.69; N, 14.65.
Found: C, 56.81; H, 3.84; N, 14.29.
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(4-amino-3-(4-
bromophenyl)-2-thioxo-2,3-dihydrothiazole-5-carboxamide)
(Compound 8): Yield 78%, m.p. 105.8°C. IR:υmax./cm−1 3464,
3363, 3236 (NH, NH2), 3100 (CH arom.), 1659 (2 C=O), 1284 (2
1
C=S), 1377, 1199 (SO2). H-NMR (DMSO-d6, D2O): δ 4.5 (s, 4H,
2NH2, exch.), 6.6–7.9 (m, 16H, Ar-H), 11.1 (s, 2H, 2 NH, exch.).
13C-NMR (DMSO-d6): 67.4 (2), 113.0 (2), 125.0 (4), 128.4 (4),
129.2 (4), 130.5 (4), 131.4 (2), 137.8 (2), 140.4 (2), 162.3 (2),
179.3 (2), 187.6 (2). Anal.Calcd. for C32H22Br2N6O4S5 (874.69): C,
43.94; H, 2.54; N, 9.61. Found: C, 44.27; H, 2.30; N, 9.28.
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(4-amino-3-phenyl-
2-thioxo-2,3-dihydrothiazole-5-carboxamide) (Compound 3):
Yield 81%, m.p. 130°C. IR:υmax./cm−1 3448, 3320, 3260 (NH,
1
NH2), 1662 (2 C=O),1290 (2 C=S), 1393, 1177 (SO2). H-NMR
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(4-amino-3-(4-
iodophenyl)-2-thioxo-2,3-dihydrothiazole-5-carboxamide)
(Compound 9): Yield 69%, m.p. 148.1°C. IR:υmax./cm−1 3367,
3224, 3120 (NH, NH2), 3093 (CH arom.), 1654 (2 C=O), 1290 (2
(DMSO-d6, D2O): δ 6.9 (s, 4H, 2NH2, exch.), 7.0–7.9 (m, 18H,
Ar-H), 8.5 (s, 2H, 2NH, exch.). Anal.Calcd. for C32H24N6O4S5
(716.90): C, 53.61; H, 3.37; N, 11.72. Found: C, 53.82; H, 3.23; N,
12.09.
1
C=S), 1392, 1195 (SO2). H-NMR (DMSO-d6, D2O): δ 4.5 (s, 4H,
2NH2, exch.), 6.6–7.9 (m, 16H, Ar-H), 11.1 (s, 2H, 2 NH, exch.).
13C-NMR (DMSO-d6): 67.4 (2), 88.9 (2), 123.6 (4), 128.6 (4),
129.2 (4), 135.7 (2), 136.2 (2), 137.3 (4), 140.1 (2), 158.6 (2),
162.2 (2), 187.3 (2). Anal.Calcd. for C32H22I2N6O4S5 (968.69): C,
39.68; H, 2.29; N, 8.68. Found: C, 39.40; H, 2.41; N, 8.33.
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(4-amino-2-thioxo-
3-p-tolyl-2,3-dihydrothiazole-5-carboxamide) (Compound 4):
Yield 76%, m.p. 105.8°C. IR:υmax./cm−1 3410, 3375, 3232 (NH,
NH2), 3070 (CH arom.), 2930, 2866 (CH aliph.), 1654 (2 C=O),
1285 (2 C=S), 1319, 1199 (SO2). 1H-NMR (DMSO-d6, D2O): δ 2.3
(s, 6H, 2 CH3), 4.5 (s, 4H, 2NH2, exch.), 6.6–7.9 (m, 16H, Ar-H),
10.9 (s, 2H, 2 NH, exch.). 13C-NMR (DMSO-d6): 20.4 (2), 67.0 (2),
123.0 (4), 126.7 (4), 128.2 (4), 129.6 (4), 130.1 (2), 133.7 (2),
135.2 (2), 142.1 (2), 154.8 (2), 162.2 (2), 186.9 (2). Anal.Calcd. for
C34H28N6O4S5 (744.95): C, 54.82; H, 3.79; N, 11.28. Found: C,
55.10; H, 3.55; N, 11.03.
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyano-
3-mercapto-3-(phenylamino)acrylamide) (Compound 11):
Yield 86%, m.p. 162.6–168°C. IR:υmax./cm−1 3448, 3380 (4 NH),
2187 (2 C≡N), 1654 (2 C=O), 1315, 1149 (SO2). 1H-NMR (DMSO-
d6, D2O): δ 2.7 (s, 2H, 2SH), 7.0–7.9 (m, 18H, Ar-H), 9.8, 10.2 (2s, 4H,
4 NH, exch.). 13C-NMR (DMSO-d6): 73.3 (2), 113.1 (2), 118.4 (4),
119.3 (2), 122.9 (4), 128.3 (4), 129.7 (4), 137.7 (2), 139.0 (2), 139.4
(2), 162.2 (2), 179.5 (2). Anal.Calcd. for C32H24N6O4S3 (652.77): C,
58.88; H, 3.71; N, 12.87. Found: C, 59.02; H, 3.96; N, 12.50.
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(4-amino-3-(4-
methoxyphenyl)-2-thioxo-2,3-dihydrothiazole-5-carboxam-
ide) (Compound 5): Yield 86%, m.p. 217.7°C. IR:υmax./cm−1
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

500 Original Article
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyano-2-
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(5-acetyl-4-amino-
2-(phenylamino)thiophene-3-carboxamide) (Compound 16):
Yield 63%, m.p. 92.4°C. IR:υmax./cm−1 3448, 3370, 3290 (NH,
NH2), 1670, 1649 (4 C=O), 1390, 1145 (SO2). 1H-NMR (DMSO-
d6, D2O): δ 2.7 (s, 6H, 2 COCH3), 5.9 (s, 4H, 2 NH2, exch.). 6.8–7.9
(m, 18H, Ar-H), 10.5 (s, 2H, 2 NHCO, exch.), 10.6 (s, 2H, 2NHPh,
exch.). 13C-NMR (DMSO-d6,): 30.7 (2), 104.5 (2), 119.1 (4), 120.4
(2), 124.5 (4), 128.4 (4), 128.7 (4), 129.1 (2), 137.4 (2), 138.8 (2),
147.3 (2), 152.6 (2), 162.2 (2), 168.7 (2), 195.4 (2). Anal.Calcd. for
C38H32N6O6S3 (764.89): C, 59.67; H, 4.22; N, 10.99. Found: C,
59.60; H, 4.19; N, 10.71.
(5-oxo-3-phenylthiazolidin-2-ylidene)acetamide) (Compound
12): Yield 62%, m.p. 193.2°C. IR:υmax./cm−1 3387 (2 NH), 3059
(CH arom.), 2194 (2 C≡N), 1730, 1660 (4 C=O), 1365, 1149
(SO2). 1H-NMR (DMSO-d6, D2O): δ 4.2 (s, 4H, 2 CH2), 6.5–7.9 (m,
18H, Ar-H), 10.8 (s, 2H, 2 NH, exch.). 13C-NMR (DMSO-d6): 78.3
(2), 85.6 (2), 113.2 (4), 117.7 (2), 119.4 (2), 123.5 (4), 128.9 (4),
129.8 (4), 139.2 (2), 142.8 (2), 148.1 (2), 163.5 (2), 173.3 (2),
193.9 (2). Anal.Calcd. for C36H24N6O6S3 (732.81): C, 59.00; H,
3.30; N, 11.47. Found: C, 59.32; H, 3.13; N, 11.29.
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyano-2-
(4-oxo-3-phenylthiazolin-2-ylidene)acetamide) (Compound 13):
Yield 86%, m.p. 162.7°C. IR:υmax./cm−1 3375 (2 NH), 2195 (2
C≡N), 1732, 1650 (4 C=O), 1390, 1188 (SO2). 1H-NMR (DMSO-
d6, D2O): δ 3.9 (s, 4H, 2 CH2 thiazole), 7.0–7.9 (m, 18H, Ar-H),
10.2 (s, 2H, 2 NH, exch.). 13C-NMR (DMSO-d6): 32.8 (2), 62.9 (2),
119.2 (2), 120.6 (4), 121.5 (4), 124.1 (2), 128.9 (4), 129.4 (4),
130.4 (2), 135.2 (2), 148.1 (2), 162.2 (2), 170.3 (2), 173.3(2). Anal.
Calcd. for C36H24N6O6S3 (732.81): C, 59.00; H, 3.30; N, 11.47.
Found: C, 59.09; H, 3.21; N, 11.51.
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(4-amino-5-benzoyl-
2-(phenylamino)thiophene-3-carboxamide) (Compound 17):
Yield 67%, m.p. 102.2°C. IR:υmax./cm−1 3433, 3394, 3200 (NH,
NH2), 1690, 1655 (4 C=O), 1315, 1145 (SO2). 1H-NMR (DMSO-
d6, D2O): δ 6.1 (s, 4H, 2 NH2, exch.). 7.1–7.9 (m, 28H, Ar-H), 10.5
(s, 4H, 4 NH, exch.). 13C-NMR (DMSO-d6): 96.8 (2), 103.8 (2),
112.9 (4), 120.9 (2), 121.5 (4), 128.5 (4), 128.7 (4), 129.9 (4),
130.0 (4), 134.3 (2), 135.6 (2), 137.9 (2), 138.3 (2), 139.9 (2),
146.2 (2), 162.7 (2), 166.4 (2), 188.1 (2) Anal.Calcd. for
C48H36N6O6S3 (889.03): C, 64.85; H, 4.08; N, 9.45. Found: C,
65.04; H, 3.89; N, 9.16.
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyano-2-
(4-methyl-3-phenylthiazol-2(3H)-ylidene)acetamide)
(Com-
pound 14): Yield 69%, m.p. 89.8°C. IR:υmax./cm−1 3448 (2 NH),
2187 (2 C≡N), 1654 (2 C=O), 1400, 1149 (SO2). 1H-NMR (DMSO-
d6, D2O): δ 1.8 (s, 6H, 2 CH3), 6.6 (s, 2H, 2CH thiazoles), 7.0–7.9
(m, 18H, Ar-H), 10.5 (s, 2H, 2 NH, exch.). Anal.Calcd. for
C38H28N6O4S3 (728.86): C, 62.62; H, 3.87; N, 11.53. Found: C,
62.91; H, 3.49; N, 11.22.
N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-amino-4,5,6,7-tet-
rahydrobenzo [b]thiophene-3-carboxamide) (Compound 19):
Yield 66%, m.p. 190.9°C. IR:υmax./cm−1 3448, 3380, 3310 (NH,
NH2), 1680 (2 C=O), 1388, 1145 (SO2). 1H-NMR (DMSO-d6,
D2O): δ 1.7–2.6 (m, 16H, 8 CH2 cyclo), 6.6 (s, 4H, 2 NH2, exch.),
6.9–7.9 (m, 8H, Ar-H), 9.3 (s, 2H, 2 NH, exch.). 13C-NMR (DMSO-
d6): 22.4 (2), 22.7 (2), 23.9 (2), 25.5 (2), 112.9 (2), 119.2 (4), 128.4
(2), 129.0 (4), 136.0 (2), 136.5 (2), 141.2 (2), 162.8 (2). 163.4 (2).
Anal.Calcd. for C30H30N4O4S3 (606.78): C, 59.38; H, 4.98; N, 9.23.
Found: C, 59.03; H, 5.11; N, 9.06.
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-cyano-
2-(3,4-diphenylthiazol-2(3H)-ylidene)acetamide) (Compound
15): Yield 78%, m.p. 78.8°C. IR:υmax./cm−1 3356, 3232 (2
NH),3055 (CH arom.), 2179 (2 C≡N), 1670 (2 C=O), 1357, 1145
(SO2). 1H-NMR (DMSO-d6, D2O): δ 6.6 (s, 2H, 2 CH thiazole), 7.0–
7.9 (m, 28H, Ar-H), 8.4 (s, 2H, 2 NH, exch.). 13C-NMR (DMSO-d6):
79.1 (2), 112.8 (2), 113.0 (4), 119.2 (4), 122.8 (4), 126.2 (4), 127.8
(2), 128.9 (4), 129.8 (4), 130.7 (4), 134.3. (2), 136.7 (2), 137.8 (2),
139.2 (2), 141.7 (2), 162.2 (2), 174.2 (2). Anal.Calcd. for
C48H32N6O4S3 (853.00): C, 67.59; H, 3.78; N, 9.85. Found: C,
68.00; H, 3.42; N, 9.49.
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene))bis(2-(4-oxothi-
azolidin-2-ylidene)acetamide) (Compound 20): Yield 80%,
m.p. 182.8°C. IR:υmax./cm−1 3325, 3201(4NH), 3100 (CH arom.),
2960, 2870 (CH aliph.), 1705, 1680 (4 C=O), 1346, 1153 (SO2).
1H-NMR (DMSO-d6, D2O): δ 3.9 (s, 4H, 2 CH2), 4.2 (s, 2H, 2 CH
thiazolidinone), 7.1–7.9 (m, 8H, Ar-H), 10.3, 10.7 (2s, 4H, 4 NH,
exch.). 13C-NMR (DMSO-d6): 38.9 (2), 90.6 (2), 119.3 (4), 128.5
(4), 136.0 (2), 143.6 (2), 161.9 (2), 169.1 (2), 171.9 (2). Anal.
Fig. 2 Co-crystallized sulfone ligand on the active
Leu
site of farnesyl transferase.
B96
Ala
A129
Asp
N
B297
2.13
Phe
Tyr
B300
B360
2.4
Ser
N
His
B99
B362 2.26
N
Zn
N
Asp
2.26
B359
Tyr
Cys
B299
O
S
B93
N
N
O
O
Gln
N
O
N
A167
2.95
Tyr
His
B149
2.83
B361
Trp
B102
Ala
B151
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

Original Article 501
Calcd. for C22H18N4O6S3 (530.60): C, 49.80; H, 3.42; N, 10.56.
energy score (S)= −25.6345Kcal/mol and root mean standard
▶
Found: C, 50.06; H, 3.18; N, 10.22.
deviation (RMSD)=2.8268 ( Fig. 2). The sulfone ligand inter-
●
acts with the active site of farnesyl transferase by 4 interactions:
Try B361 with a hydrogen bond of 2.95A° and arene-arene
interaction, Trp B102 with a hydrogen bond of 2.83 and with Zn
by the lone pair of imidazole nitrogen. All synthesized com-
pounds were fit to the active site of farnesyl transferase enzyme
with good energy scores (S) suggesting activity as farnesyl
Molecular Docking
Molecular docking on the active site of farnesyl
transferase (FT)
The protein data bank file (PDB: 3E30) was selected for this pur-
pose. The file contains farnesyl transferase enzyme co-crystal-
lized with a sulfone ligand. All docking procedures were achieved
by MOE (Molecular Operating Environment) software 10.2008
provided by chemical computing group, Canada. Docking on the
active site of farnesyl transferase enzyme was performed for all
synthesized compounds.
transferase inhibitors. Energy scores (S) and amino acid interac-
▶
tions for the synthesized compounds were listed in Table 1.
●
Compound 11 gave the best energy score (S)= −36.8099 and
interacted with Arg B202 with a hydrogen bond of 2.64A°, Asp
B352 with a hydrogen bond of 1.4A° and with Zn through its
▶
Docking protocol was verified by redocking of the co-crystal-
lized ligand in the vicinity of the active site of the enzyme with
carboxamido group ( Fig. 3). 3D interaction of compound 3
●
Table 1 Binding scores and
amino acid interactions of the
docked compounds on the active
site of farnesyl transferase (FT).
Compound No.
S Kcal/Mol
Amino acid interactions
H bond length Ao
Interaction with Zn
2
3
−22.2685
−29.4698
Leu B295, Lys B294
Ser B99, Asp B297
Asp B352
3.37, 2.76
3.30, 2.4
2.8
No interaction
C=O
4
−35.6889
His B245, Arg B291
Asp B452
2.61, 3.05
1.45
C=O
5
6
−30.746
Lys B294
2.69
C=O
−20.4074
Lys A164, Tyr B301
Lys B356
2.89, 2.57
2.44
No interaction
7
8
9
−36.6898
−28.5758
−23.3689
Arg B357
1.48–1.48
2.82
C=O
Lys B294
No interaction
No interaction
Lys B294, Arg B291
Lys B356, Lys B363
Arg B202, Asp B352
Tyr A168, Ser B99
Arg B291
2.87, 2.77
2.93, 3.11
2.64, 1.4
2.65, 2.91
3.30
11
12
−36.8099
−33.2105
C=O
CN
13
14
15
16
17
19
−27.7094
−30.7510
−36.6799
−37.5820
−36.3035
−27.9411
Arg B291, Gln A167
Arg B202
2.69, 2.80
3.62
CN
C=O
Lys B356, Ser B99
Lys B356
2.79, 2.93
2.42
No interaction
No interaction
No interaction
No interaction
Lys B356
2.58
Arg B291, Tyr A168
Tyr B251
2.67, 2,92
3.02
20
−33.5881
Lys A164, Ser B99
2.54, 1.87–2.63
C=O
Fig. 3 Compound 11 on the active site of farnesyl
transferase.
Gln
A167
Ser
B99
Ala
B98
Trp
B106
Tyr
B300
Tyr
A166
Tyr
B361
Trp
B102
HS
N
H
His
B362
Cys
B299
N
Asp
B297
2.26
O
S
2.26
O
2.13
2.4
H
N
Zn
N
H
2.64
Asp
B359
O
N
O
Arg
B202
Asp
B352
N
1.4
H
SH
His
B248
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

502 Original Article
Gly
80
Glu
100
Glu
144
Cys
101
Gly
78
1.81
Ser
79
1.85
H
O
1.81
H
Gly
126
H
+ NH
O
N
S
2
Arg
54
2.64
O
O
N
O
His
45
lle
83
N
Lys
127
H
N
2
N
Leu
84
Leu
48
Met
155
3
Val
128
Glu
129
Fig. 4 Compound 3 on the active site of farnesyl transferase.
Thr
158
with the amino acid of active site of the enzyme is illustrated in
Fig. 5 Co-crystallized S-adenosyl methionine ligand on the active site of
arginine methyl transferase (PRMT1).
▶
(
Fig. 4) .
●
Molecular docking on the active site of arginine methyl
transferase (PRMT1)
Table 2 Binding scores and amino acid interactions of the docked
compounds on the active site of arginine methyl transferase (PRMT1).
The protein data bank file (PDB: 3Q7E) was selected for this pur-
pose. The file contains arginine methyl transferase co-crystallized
with its ligand, S-adenosyl methionine. All docking procedures
were achieved by MOE (Molecular Operating Environment) soft-
ware 10.2008 provided by chemical computing group, Canada.
Docking on the active site of arginine methyl transferase enzyme
was performed for all synthesized compounds.
Docking protocol was verified by redocking of the co-crystal-
lized ligand in the vicinity of the active site of the enzyme with
energy score (S)= −18.5932 Kcal/mol and root mean standard
deviation (RMSD)=0.3523. The ligand interacts with the active
site of arginine methyl transferase by 5 interactions: Val 128
with a hydrogen bond of 3.00A°, Arg 54 with a hydrogen bond
Compound
No.
S Kcal/Mol
Amino acid
interactions
H bond
length A°
2
3
−20.0584
−22.9402
−14.2954
−18.2714
−23.0610
−16.0863
−25.5443
−18.6599
−21.7302
Lys 127, His 293
Lys 127
2.65, 2.81
2.46
4
Thr 158, Glu 100
Glu 130, Lys 127
Arg 327, Lys 127
Arg 327
2.75, 2.15–2.48
1.41, 2.47
2.89, 1.27
3.20
5
6
7
8
Lys 127
2.44
9
Lys 127, Arg 327
Glu 130, Lys 127
Arg 327
2.45, 2.47
1.34, 2.52
2.31
11
12
13
−25.2873
−21.1864
Lys 127, Arg 327
Asn 157, Lys 127
Arg 327
2.68, 3.14
2.68, 2.74
2.92
of 2.64, Gly 78 with a hydrogen bond of 1.81A° and Glu 100 with
▶
2 hydrogen bonds of 181, 186A° ( Fig. 5). All synthesized com-
●
pounds were fit to the active site of arginine methyl transferase
enzyme with good energy scores (S) suggesting activity as
arginine methyl transferase inhibitors for most of the synthe-
14
15
16
17
−23.3643
−18.4392
−20.8016
−33.0593
Arg 327
2.96–2.32
2.85, 3.11
1.81, 2.69–2.89
1.27, 2.66
2.68
His 45, Thr 185
Glu 100, Arg 327
Glu 130, His 45
Lys 127
sized compounds. Energy scores (S) and amino acid interactions
▶
for the synthesized compounds were listed in Table 2. C o m -
●
19
20
−18.1701
−20.3841
Gly 78, Glu 100
Lys 127, His 45
1.77, 1.96
2.78, 1.90
pound 17 gave the best energy score (S)=-33.0593 and inter-
acted with His 45 with a hydrogen bond of 2.66A°, Lys 127 with
a hydrogen bond of 2.68A°, Glu 130 with a hydrogen bond of
1.27Ao and Arg 327 & His 161 by arene cation interactions
(MCF7). The response parameter calculated was the IC50 value,
which corresponds to the concentration required for 50% inhibi-
tion of cell viability.
▶
(
Fig. 6). 3D interaction of compound 3 with the amino acid of
●
▶
active site of the enzyme is illustrated in Fig. 7.
▶
●
●
Table 3 shows the in vitro cytotoxic
activity of the synthesized compounds where all compounds
Biological screening
exhibited significant activity compared to the reference drug.
In vitro antitumor activity
The newly synthesized compounds were evaluated for their in
vitro cytotoxic activity against human breast cancer cell line,
MCF7. Doxorubicin which is one of the most effective anticancer
agents was used as the reference drug in this study. The relation-
ship between surviving fraction and drug concentration was
plotted to obtain the survival curve of breast cancer cell line
Discussion
▼
Chemistry
The synthetic procedures adopted to obtain the target com-
pounds are depicted in Fig. 8–11. N,N′-(4,4′-sulfonylbis(4,1-
▶
●
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

Original Article 503
Fig. 6 Compound 17 on the active site of ar-
ginine methyl transferase (PRMT1).
Arg
327
O
O
S
O
NH
S
His
41
2
N
H
His
45
2.66
O
HN
Ser
Met
155
HN
154
H
N
O
2.68
Glu
Lys
Leu
48
153
127
Ser
102
lle
44
His
S
NH
H
161
Thr
158
Glu
129
1.37
Glu
O
Glu
144
130
(DMSO-d6) revealed a singlet signal at 4.5ppm for NH2 which
was exchanged by D2O. Also, the IR spectra for compounds 7–9
showed the corresponding bands for NH2, C=S and SO2 groups.
1H-NMR spectra for compounds 7–9 revealed signals corre-
sponding to the presence of NH2 groups.
Thesynthesisof(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-pheneylene)-
bis(2-cyano-3-mercapto-3-(phenylamino)acrylamide 11 and
(2E,2′E)-N,N′-(4,4′-sulfonylbis(4,1-phenylene)-bis(2-cyano-
2-(5-oxo-3-phenylthiazolidin-2-ylidene)acetamide 12 were
achieved. Treatment of acetamide 2 with phenyl isothiocyanate
in dry dimethylformamide in the presence of equivalent amount
of potassium hydroxide produced the potassium salt 10, which
acidification of such potassium salt 10 liberated the acrylamide
derivative 11, whereas reaction with chloroacetyl chloride in
dry dimethylformamide to afford thiazolidinone derivative 12.
The structures of compounds 11 and 12 were proved on the
basis of elemental analyses and spectral data. Thus, IR spectrum
of 11 exhibited characteristic band at 3448cm−1 (4 NH),
1
2187cm−1 (2 C≡N) and 1645cm−1 for (2 C=O). H-NMR spec-
trum of 11 revealed signals at 2.7ppm for SH groups and
10.2ppm for NH groups. IR spectrum of 12 showed bands at
3387cm−1 (2 NH), 2194cm−1 (2 C≡N) and 1730, 1660cm−1 for
(4 C=O). 1H-NMR spectrum of 12 revealed signals at 4.2ppm
Fig. 7 Compound 3 on the active site of arginine methyl transferase
(PRMT1).
corresponding to CH2 groups and 10.8ppm due to NH groups
▶
phenylene))bis(2-cyanoacetamid) 2 was prepared via reaction
Fig. 9) .
(
●
of Dapson 1 with ethyl cyanoacetate under condition of fusion
The reactivity of the acetamide derivative 2 towards isothiocy-
anate was investigated. Thus, when compound 2 was left to react
with phenyl isothiocyanate in the presence of dilute solution of
potassium hydroxide at room temperature and ethyl chloroace-
▶
(
Fig. 8). Compound 2 was characterized by the presence of
●
absorption band at 2256cm−1 for (2 C≡N), and a strong absorp-
tion band at 1701cm−1 for (2 C=O). 1H-NMR spectrum in
(DMSO-d6) revealed signals at 4.0ppm represents CH2 protons
and 10.7ppm corresponding to NH groups. Also, compounds
3–9 were obtained by reacting compound 2 with sulfur and
isothiocyanate derivatives. The IR spectra of compounds 3–9,
exhibited the absence of (C≡N) band & presence of characteristic
tate was added, the corresponding thiazolidinone derivative 13
▶
was obtained as a clean cut product in good yield ( Fig. 10).
●
Compound 13 was proved on the basis of analytical and spectral
data. Thus, IR spectrum of 13 showed band at 3375cm−1 (2 NH),
1
2195cm−1 (2 C≡N) and 1732, 1650cm−1 for (4 C=O). H-NMR
1
bands for NH2, SO2 and C=S groups. H-NMR spectrum of 3 in
spectrum of 13 revealed signals at 3.9ppm for CH2 groups,
10.2ppm to NH groups.
(DMSO-d6) exhibited signals at 6.9ppm due to NH2 groups and
8.5ppm corresponding to NH groups. 1H-NMR spectrum of 4 in
(DMSO-d6) exhibited signals at 2.3ppm due to CH3 groups,
4.5ppm corresponding to NH2 groups. 1H-NMR spectrum of 5 in
(DMSO-d6) revealed signal at 3.8ppm corresponding to OCH3
groups. IR spectrum for compound 6 showed the characteristic
bands for NH2 and C=S groups. 1H-NMR spectrum of 6 in
Similarly, the novel phenylthiazole 14 was synthesized by reac-
tion of 2 with phenyl isothiocyanate in the presence of potas-
sium hydroxide at room temperature and chloroacetone was
added, the corresponding phenylthiazole derivative 14 was
obtained as a clean cut product in a good yield. Probably the
reaction mechanism is assumed to proceed via initial alkylation
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

504 Original Article
Table 3 In vitro anticancer screening of the synthesized compounds against human breast cell line (MCF7).
Comp NO.
Compound concentration (μM)
50μM
IC50 (μM)
10μM
25μM
100μM
Surviving fraction (Mean±S.E.)*
Doxorubicin
0.721±0.02
0.546±0.02
0.461±0.01
0.494±0.03
71.80
46.57
23.02
57.67
51.07
32.19
33.67
42.71
31.59
41.87
42.00
44.15
41.57
37.02
43.36
56.34
33.34
49.37
2
3
0.727±0.134
0.390±0.043
0.851±0.188
0.821±0.068
0.444±0.010
0.582±0.108
0.715±0.064
0.458±0.099
0.623±0.120
0.818±0.071
0.873±0.083
0.502±0.007
0.746±0.096
0.634±0.184
0.637±0.098
0.425±0.056
0.793±0.055
0.427±0.055
0.320±0.037
0.521±0.062
0.564±0.092
0.310±0.064
0.277±0.085
0.407±0.056
0.344±0.112
0.419±0.206
0.418±0.088
0.358±0.197
0.434±0.027
0.292±0.075
0.454±0.046
0.491±0.081
0.269±0.094
0.454±0.097
0.307±0.029
0.166±0.640
0.412±0.016
0.301±0.061
0.342±0.085
0.247±0.066
0.286±0.060
0.271±0.007
0.251±0.054
0.233±0.010
0.280±0.084
0.255±0.045
0.233±0.083
0.301±0.040
0.419±0.052
0.321±0.076
0.292±0.008
0.317±0.021
0.273±0.156
0.351±0.016
0.300±0.046
0.289±0.071
0.297±0.033
0.277±0.047
0.300±0.034
0.332±0.044
0.225±0.041
0.238±0.086
0.410±0.028
0.221±0.050
0.298±0.097
0.406±0.057
0.435±0.040
0.332±0.050
4
5
6
7
8
9
11
12
13
14
15
16
17
19
20
*Each value is the mean of 3 values±Standard Error
Fig. 8 Synthetic pathways for compounds 2–9.
O
NC
O
S
O
O
O
O
S
HN
NH
CN
H N
NH
fusion
NC
O
2
O
1
DMF
EtOH
TEA
S. ArNCS
3, Ar = C6H5
4, Ar = C6H4CH3-4
5, Ar = C6H4OCH3-4
6, Ar = C6H4NO2-4
7, Ar = C6H4Cl-4
8, Ar = C6H4Br-4
9, Ar = C6H4I-4
O
O
O
S
HN
NH
NH
H N
O
S
S
S
N
N
Ar
Ar
3–9
S
Fig. 9 Synthetic pathways for compounds 11
and 12.
O
S
O
O
KOH/DMF
PhNCS
HN
NH
PhHN
2
CN
NC
O
NHPh
+
-
- +
S K
K S
10
Cl
Cl
dil.HCl
DMF
O
O
O
S
O
S
O
S
O
O
HN
S
NH
Ph
HN
NHPh
NH
CN
NC
CN
NC
O
O
Ph
N
PhHN
N
SH
HS
12
11
O
O
followed by in situ heterocyclization through nucleophilic addi-
tion of secondary amino group to carbonyl group of chloroace-
tone to yield the cyclic product 14. Also, the diphenylthiazole
derivative 15 was obtained by the same conditions of preparing
compound 14 but using phenacyl chloride instead of chloroace-
tone. The structure of compound 14 and 15 were established on
the basis of elemental and spectral data. Thus, IR spectrum of
compound 14 exhibited bands at 3448cm−1 (2 NH), 2187cm−1
1
(2 C≡N), 1654cm−1 (2 C=O). H-NMR spectrum of 14 revealed
signals at 1.8ppm for 2CH3 groups and 6.6ppm corresponding to
2CH of thiazoles. IR spectrum of compound 15 exhibited bands
at 3356, 3232cm−1 (2 NH), 2179cm−1 (2 C≡N), 1670cm−1
(2 C=O). 1H-NMR spectrum of 15 revealed signals at 6.6ppm
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

Original Article 505
Fig. 10 Synthetic pathways for compounds
13–17.
OEt
O
S
O
O
Cl
Cl
HN
Ph
N
NH
O
CN
CN
NC
NC
O
Ph
EtOH / DMF
N
S
S
13
11
O
O
R
O
S
O
O
HN
NH
R
O
O
EtOH / DMF
Cl
Ph
Ph
O
N
N
- HCl
S
S
EtOH / DMF
TEA
14, R = CH3
15, R = Ph
R
R
O
S
O
O
HN
NH
CN
NC
O
NHPh
PhHN
S
S
O
O
R
R
NHEt3Cl
O
S
O
O
NH
NH
C
R
N
N
C
R
O
NHPh
PhHN
S
S
O
O
O
O
O
NH
S
NH
N
N
O
O
O
NHPh
PhHN
S
S
R
R
NHEt3Cl
O
S
O
O
NH
NH
NH
H
HN
H
O
O
O
NHPh
PhHN
S
S
R
R
O
O
O
NH
S
NH
NH2
R
H2N
R
O
O
O
NHPh
PhHN
S
S
16, R = CH3
17, R = Ph
corresponding to 2CH of thiazoles and 8.4ppm corresponding to
2NH groups.
in a mixture of DMF/EtOH containing a catalytic amount of mor-
pholine. The reaction may be explained via intermediate 18
▶
In continuation of our work on the synthesis of biologically
interesting heterocyclic molecules containing thiophene moiety
[25–28], several thiophene derivatives have been synthesized
with a view to evaluate their anticancer activities. Thus, reflux-
ing of 11 in DMF/EtOH containing a catalytic amount of triethyl-
amine, chloroacetone and/or phenacyl chloride revealed
formation of the thiophene derivatives 16 and 17, respectively.
The IR spectra of compounds 16 and 17 were characterized by
the disappearance of C≡N groups band and the appearance of
NH2 and C=O bands. In addition, the 1H-NMR spectrum of 16 in
(DMSO-d6) showed 3 singlet signals at 2.7, 10.5 and 10.6ppm
due to COCH3, NHCO and NHPh protons, respectively.
(
●
Fig. 11). The structure of compound 19 was established on
the basis of its elemental analysis and spectral data; its IR spec-
trum showed the presence of bands at 3448, 3380, 3310cm−1
(NH, NH2), 1680cm−1 (2 C=O) and 1388, 1149cm−1 (SO2).
1H-NMR spectrum of 19 in (DMSO-d6) displayed a multiplet at
1.7–2.6ppm corresponding to tetrahydrobenzene moieties.
Moreover, 13C-NMR spectrum revealed signals at 22.4, 22.7, 23.9
and 25.5ppm due to tetrahydrobenzene nucleus.
Finally, reaction of compound 2 with 2-sulfanylacetic acid
afforded the thiazolidinone derivative 20 ( Fig. 11). Compound
20 was characterized by the presence of a strong absorption
band at 1705cm−1 in the IR spectrum, specific for the thiazo-
lidinone ring. Another piece of evidence for cyclization, in the
1H-NMR spectrum is the presence of a singlet signal, equivalent
▶
●
On the other hand, the tetrahydrobenzothiophene derivative 19
was obtained by the reaction of 2 with cyclohexanone and sulfur
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

506 Original Article
Fig. 11 Synthetic pathways for compounds
18–20.
O
S
O
O
HN
NH
NH2
H2N
O
S
S
19
Sulphur Morpholine
O
O
O
O
HN
S
NH
CN
NC
O
Morpholine
18
2
OH
O
O
S
O
O
HS
HN
NH
S
S
O
N
H
N
H
AcOH
O
O
20
to 2 protons at 3.9ppm which represents the C-5 protons of thia-
zolidinone nucleus. 13C-NMR spectrum of compound 20 showed
signals at 169.1 and 90.6ppm due to C-4 and C-5 of the thiazo-
lidinone nucleus, respectively.
sites of both farnesyl transferase enzyme and arginine methyl-
transferase enzyme may provide a tool to predict the possibility
of their cytotoxic compounds as inhibitors for these 2 enzymes.
However, no defined relationship between the biological activ-
ity and the docking results could be identified suggesting more
investigation to be conducted in order to specify their mecha-
nism of action.
Molecular Docking
Advances in molecular biology over the past decade have identi-
fied a number of novel targets for cancer therapy. One such
target is the enzyme farnesyl protein transferase (FT), which
catalyses a key step in the addition of an aliphatic isoprenoid
side chain to a number of proteins. A novel class of antineoplas-
tic agents, the farnesyl transferase inhibitors (FTIs), have recently
been developed to specifically inhibit FT. These inhibitors were
designed to target Ras, a G-protein with 4 isoforms (H-, N- and
K-RasA/K-RasB) mutated in a large number of cancers, which
requires prenylation for functioning [30]. Despite uncertainty
about the true target of FTIs, these agents demonstrate antican-
cer activity as single agents and in combination with standard
cytotoxic chemotherapy [31–33]. In addition, FTIs synergize
with gamma irradiation, and may have a role in chemopreven-
tion [34–36].
On the other hand, Methylation at arginine residues is of interest
because it can affect gene transcription, or signal transduction
by modulating protein-protein interactions [37]. In mammalian
cells methylation of arginine residues is catalyzed by a family of
at least 9 protein methyl transferases (PRMTs, E.C. 2.1.1.125)
[38]. Arginine methyl transferase (PRMT1) is thought to contrib-
ute to as much as 85% of all cellular PRMT activity and its inhibi-
tion may lead to good antitumor activity [39].
Biological screening
In vitro antitumor activity
All the synthesized compounds showed better cytotoxic activity
than Doxorubicin especially the thiazolidinone derivative 3
which showed IC50 value 23.02 μM. Upon substitution on the
phenyl rings of compound 3 with several electron donating and
electron withdrawing groups the activity drops. However, sub-
stitution with electron withdrawing groups did not decrease the
activity in the same way substitution with electron donating
group did. This was clearly illustrated by the values of IC50 of the
thiazolidinone derivatives 6 and 9 with IC50 values of 32.19μM
and 31.59μM, respectively. In these 2 derivatives, substitution of
the phenyl rings was with NO2 in case of compound 6 and I in
case of compound 9. On the other hand, the IC50 values for the
thiazolidinone derivatives in which the substitution on the phe-
nyl rings was with electron donating groups were much higher
indicating less activity. This was clearly shown in the thiazolidi-
none derivatives 4 and 5 with IC50 values of 57.67μM and
51.07μM, respectively. In these 2 derivatives, substitution of the
phenyl rings was with CH3 in case of compound 4 and OCH3 in
case of compound 5.
Upon the preceding, the present investigation is concerned with
the synthesis of novel anticancer agents and trying to elucidate
their mechanism of action by performing molecular docking on
the active sites of farnesyl transferase (FT) and arginine methyl
transferase (PRMT1).
The trial in the present investigation to predict an assumption
on the mechanism of action of the synthesized compounds was
conducted through molecular docking on the active site of 2
enzymes based on the similarities between the synthesized
compounds and the enzyme inhibitors of these enzymes.
The good energy scores (S) for all synthesized compounds as
well as the good amino acid interactions shown on the active
Compounds 11–20 showed cytotoxic activity with IC50 in the
range of 33.34–56.35μM with cytotoxic activity better than that
of Doxorubicin. The cyclohexyl thiazole derivative 19 was with
the best IC50 =33.34μM among these compounds while the
(phenylamino)thiophene-3-carboxamide derivative 17 showed
the highest IC50 =56.35μM among these compounds.
The promising results of cytotoxic activity of the synthesized
compounds especially compound 3 urge more investigations for
their mechanism of action. The trial in the present investigation
to predict an assumption on the mechanism of action of the syn-
thesized compounds was conducted through molecular docking
on the active site of 2 enzymes based on the similarities between
Ghorab MM et al. Synthesis and molecular docking of… Arzneimittelforschung 2012; 62: 497–507

Original Article 507
18 Boateng CA, Eyunni SVK, Zhu XY et al. Benzothieno[3,2-b]quinolinium
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Acknowledgements
▼
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The authors are grateful to the sponsorship of the College of
Pharmacy Research Centre and the Deanship of the Scientific
Research, King Saud University, Riyadh, Saudi Arabia.
Conflict of Interest
▼
The authors declare no conflict of interest.
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