Synthesis, characterization, and biological evaluation of certain 1,3-thiazolone derivatives bearing pyrazoline moiety as potential anti-breast cancer agents

Article abstract of DOI:10.1007/s00044-012-0098-7

A series of 5-arylidene-2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-1,3- thiazol-4(5H)-ones were synthesized and screened for their in vitro antitumor activity against human breast adenocarcinoma cell line (MCF-7). Five of the test compounds exhibited good antitumor activity superior to the reference drug, doxorubicin, with IC₅₀ range 1.4-2.3 μM. Among the test compounds, 2-[3,5-bis(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]-5-(2- methoxybenzylidene)-1,3-thiazol-4(5H)-one (3i) was found to show the most potent anticancer activity.

Full text of DOI:10.1007/s00044-012-0098-7

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2013) 22:1021–1027
DOI 10.1007/s00044-012-0098-7
ORIGINAL RESEARCH
Synthesis, characterization, and biological evaluation of certain
1,3-thiazolone derivatives bearing pyrazoline moiety as potential
anti-breast cancer agents
•
Nadia A. Khalil Eman M. Ahmed
•
Hala B. El-Nassan
Received: 23 December 2011 / Accepted: 15 May 2012 / Published online: 27 May 2012
Ó Springer Science+Business Media, LLC 2012
Abstract A series of 5-arylidene-2-(3,5-diaryl-4,5-dihy-
dro-1H-pyrazol-1-yl)-1,3-thiazol-4(5H)-ones were synthe-
sized and screened for their in vitro antitumor activity
against human breast adenocarcinoma cell line (MCF-7).
Five of the test compounds exhibited good antitumor
activity superior to the reference drug, doxorubicin, with
IC50 range 1.4–2.3 lM. Among the test compounds,
2-[3,5-bis(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]-
5-(2-methoxybenzylidene)-1,3-thiazol-4(5H)-one (3i) was
found to show the most potent anticancer activity.
new, potent, selective, and less toxic anticancer agents is
still a major challenge to medicinal chemistry researchers.
The increasing diversity of small molecule libraries is an
important source for the discovery of new drug candidates.
In terms of this trend, many pyrazoline derivatives have
been reported to possess antitumor and antiproliferative
potential (Johnson et al., 2007; Shaharyar et al., 2010;
Congiu et al., 2010; Bashir et al., 2011; Lv et al., 2011;
Wang et al., 2011; Havrylyuk et al., 2011).
4-Thiazolidinone derivatives represent another class of
anticancer drugs that have attracted a special attention of
medicinal chemists (Hafez and El-Gazzar, 2009; Havrylyuk
et al., 2010; Lv et al., 2010). Their antineoplastic properties
may be attributed to their affinity to anticancer biotargets
such as JNK-stimulating phosphatase-1 (JSP-1) (Cutshall
et al., 2005), tumor necrosis factor TNFa (Carter et al.,
2001), anti-apoptotic biocomplex Bcl-XL-BH3 (Degterev
et al., 2001), and integrin avb3 receptor (Dayam et al., 2006).
As a part of our ongoing research in discovery of new
active anticancer compounds (El-Nassan, 2011), in this
study, we try to study the influence of pyrazoline moiety
and thiazolone scaffold combination on the anti-breast
cancer activity and SAR analysis within these series. The
structural variations were explored by placing the pyrazo-
line moiety in position 2 of 1,3-thiazolone ring and intro-
duction of different arylidene substituents in position 5 of
1,3-thiazolone function.
Keywords Pyrazoline ꢀ 1,3-Thiazolone ꢀ
Antitumor activity ꢀ MCF-7
Introduction
Breast cancer remains the most commonly diagnosed cancer
amongwomen(Smithetal.,2009). Theoverall survival rate of
breast cancer patients has substantially increased during the
last decades due to early tumor detection (Shien et al., 2009;
Lewis et al., 2010). However, the low recovery rate of
advanced breast cancer by currently available treatment
modalities may be attributed to the development of resistance
against the existing anticancer drugs (Higa, 2009). Besides,
most of chemotherapeutics cause general toxicity to any pro-
liferating cells, which can severely limit the therapeutic value
of these drugs (Chari, 2008). Therefore, the identification of
novel structures that can be potentially useful in designing
Results and discussion
N. A. Khalil ꢀ E. M. Ahmed (&) ꢀ H. B. El-Nassan
Pharmaceutical Organic Chemistry Department,
Faculty of Pharmacy, Cairo University,
Cairo 11562, Egypt
Chemistry
The synthesis of the target compounds is outlined in
Scheme 1. The chalcone derivatives 1a and 1b were
e-mail: dr_eman2001@hotmail.com
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Med Chem Res (2013) 22:1021–1027
X
Scheme 1 Reagents and
O
conditions: a NaOH/ethanol/
reflux 8 h, b apporpriate aromic
aldehyde/ClCH2COOH/glacial
acetic acid, reflux 15 h
a
H
B
NH2CSNHNH2
+
H
A
H
X
X
Cl
N
N
Cl
1 a,b
S
NH2
2 a,b
b
X
R
X
N
N
3a
3b
3c
3d
3e
3f
3g
3h
3i
Br
Br
Br
Br
Br
Br
Cl
Cl
Cl
Cl
Cl
Cl
H
4-Cl
2-OCH3
4-OCH3
2-NO2
3-NO2
H
Cl
S
N
O
4-Cl
R
2-OCH3
4-OCH3
2-NO2
3-NO3
3j
3k
3l
3 a-l
synthesized via reacting 4-bromo- or 4-chloroacetophenone
with 4-chlorobenzaldehyde (Davey and Gwilt, 1953; Straus
and Ackermann 1909). Cyclization of 1a or 1b with thio-
semicarbazide afforded 3,5-diaryl-4,5-dihydropyrazole-1-
carbothioamides 2a and 2b, respectively (El-Enany et al.,
2010; Chimenti et al., 2010). The target compounds 3a–3l
were prepared in 32–74 % yields through the reaction of
the pyrazoline derivatives 2a or 2b with chloroacetic acid
and the respective aromatic aldehyde in glacial acetic acid.
The formation of the target compounds 3a–3l was con-
firmed by spectral data. The IR spectra of compounds 3a–3l
revealed the disappearance of NH2 characteristic bands at
3,300–3,200 cm-1 and appearance of C=O band in the range
3a–3l are in accordance with their structure. All compounds
showed molecular ion peaks corresponding to M, M?2,
M?4 (and M?6 in the spectra of compounds 3b and 3h).
The possible fragmentation pattern of these molecular ions
is suggested to takes place by two pathways (a) and
(b) (Fig. 1). Pathway (a) involves the production of promi-
nent fragments due to loss of 4-bromo- or 4-chlorobenzo-
nitrile [XC6H4CN], giving rise to the corresponding
aziridine radical cation. On the other hand, fission by path-
way (b) results in the formation of m/z fragments corre-
sponding to [RC6H4CHCS]. Compound 3g was chosen as a
representative for characteristic fragmentation pattern, and
is presented in Fig. 1.
1
of 1,681–1,716 cm-1. The H-NMR spectra showed the
characteristic ABX system (Bashir et al., 2011), which is
attributed to geminal–vicinal coupling between the two
protons at position 4 of pyrazoline ring (HA and HB) and the
proton at position 5 of the same ring (HX). The proton HA
appeared as doublet of doublets at d 3.40–3.57 ppm
indicating trans configuration to HX and geminal to HB
(JAB = 18–19 Hz, JAX = 3.9–4.5 Hz). The proton HB
exhibited doublet of doublets at d 4.01–4.17 ppm indicating
cis configuration and vicinal to HX. Besides, the doublet of
doublets around d 5.87–5.92 ppm (JBX = 9.4–13.3 Hz) was
assignable to Hx proton. On the other hand, the methine
proton of thiazolone ring was observed as a singlet signal in
the range of 7.8–8.4 ppm. Mass spectra of the compounds
In vitro anticancer screening
All the synthesized compounds were tested for their pos-
sible in vitro cytotoxic activity against human breast car-
cinoma cell line, MCF-7. Doxorubicin was used as the
positive control in this study.
The survival curve which presented the relationship
between the percentage cell viability and drug concentra-
tion of breast cancer cell line (MCF-7) was plotted for all
test compounds. The IC50 value, which corresponds to the
concentration required for 50 % inhibition of cell viability,
was determined for the test compounds and doxorubicin
(Table 1; Fig. 2).
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Med Chem Res (2013) 22:1021–1027
1023
Cl
Cl
N
N
(a)
N
N
+
Cl
(b)
S
S
S
N
O
_
Cl
CN
O
pathway (b)
3g
pathway (a)
C8H6S
C25H17Cl2N3OS
477
C18H13ClN2OS
m/z
134 (100%)
m/z
340 (15.78%)
342 (6.71%)
m/z
(8.11%) (M)
m/z
479
481
m/z
m/z
(4.52%) (M+2)
(0.93%) (M+4)
Fig. 1 The possible fragmentation pattern of compound 3g
Table 1 Results of in vitro cytotoxic activity of the synthesized
compounds and doxorubicin on human breast adenocarcinoma cell
line (MCF-7)
IC50 in µM
50
45
40
35
30
25
20
15
10
5
Compd. no.
IC50 (lM)
3a
1.6
2.3
3b
3c
7.3
0
3d
1.7
3a 3b 3c 3d 3e 3f 3g 3h 3i
3j 3k
3l Dox
3e
1.6
Fig. 2 IC50 in lM of the synthesized compounds and doxorubicin
against human breast adenocarcinoma cell line (MCF-7)
3f
13.6
5.2
3g
3h
17.3
1.4
Conclusion
3i
3j
5.3
In summary, 5-arylidene-2-(3,5-diaryl-4,5-dihydro-1H-
pyrazol-1-yl)-1,3-thiazol-4(5H)-ones were synthesized and
evaluated for their cytotoxic activities against human breast
adenocarcinoma cell line (MCF-7). The results revealed
that the bromo-substituted derivatives 3a–3f were gener-
ally more potent than their chloro analogs 3g–3l. Com-
pounds 3a, 3d, 3e, and 3i displayed excellent cytotoxic
activity with IC50 ranging from 1.4 to 1.7 lM, superior to
the reference drug, doxorubicin. Accordingly, this class of
compounds could be considered as useful templates for
future development and further derivatization or modifi-
cation to obtain more potent and selective antitumor
agents.
3k
46.6
5.3
3l
Doxorubicin
2.9
In general, the test compounds 3a–3f (X = Br) proved
to be biologically more potent than the compounds 3g–3l
(X = Cl). Besides, compounds 3a, 3b, 3d, 3e, and 3i
exerted good antitumor activity superior to the reference
drug, doxorubicin, with IC50 range between 1.4 and
2.3 lM. However, compounds 3c, 3g, and 3j showed
moderate cytotoxic activity with IC50 range between 5.2
and 7.3 lM. On the other hand, compounds 3f, 3h, 3k, and
3l showed weak cytotoxic activity with IC50 [ 13.6 lM.
Compound 3i (R = 2-CH3O, X = Cl) displayed the most
potent cytotoxic effect among the test compounds with
IC50 = 1.4 lM. In contrast, the lowest activity was
observed with the test compound 3k bearing 2-nitro group
on the benzylidene function.
Experimental
Melting points were determined on a Griffin apparatus and
were uncorrected. IR spectra were determined as KBr disks
on Shimadzu IR 435 spectrophotometer and values were
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Med Chem Res (2013) 22:1021–1027
represented in cm-1. H-NMR were carried out on Varian
Gemini 300 MHz spectrophotometer, Cairo University,
Cairo, Egypt, using TMS as an internal standard and
chemical shifts were recorded in ppm on d scale. Mass
spectra were run on Hewlett Packard 5988 spectrometer,
Microanalytical center, Cairo University, Cairo, Egypt.
Elemental analyses were carried out at the Microanalytical
center, Cairo University, Cairo, Egypt, and at the Micro-
analytical laboratory, National Research Center, Cairo,
Egypt. Progress of the reactions was monitored by TLC
using TLC sheets precoated with UV fluorescent silica gel
Merck 60 F 254 that were visualized using UV lamp.
1,3-Diaryl-2-propen-1-ones 1a and 1b (Davey and
Gwilt, 1953; Straus and Ackermann 1909), 3-(4-bromo-
phenyl)-5-(4-chlorophenyl)-4,5-dihydropyrazole-1-carbothioa-
mide (2a) (El-Enany et al., 2010), and 3,5-bis(4-chlo-
rophenyl)-4,5-dihydropyrazole-1-carbothioamide (2b) (Chim-
enti et al., 2010) were prepared according to the literature
procedures.
DMSO-d6) d ppm 3.48 (dd, 1H, HA, JAB = 18.4 Hz,
JAX = 4.3 Hz), 4.12 (dd, 1H, HB, JAB = 18.4 Hz,
JBX = 11.2 Hz), 5.91 (dd, 1H, Hx, JAX = 4.3 Hz,
JBX = 11.2 Hz), 7.31–7.94 (m, 12H, Ar–H), 8.18 (s, 1H,
=CH); MS m/z [ %]: 561 [(M?6)?, 1.69], 559 [(M?4)?,
7.47], 557 [(M?2)?, 12.82], 555 [M?, 8.84], 183
[81BrC6H4CN, 4.83], 181 [79BrC6H4CN, 4.83], 170
[37ClC6H4CHCS, 36.46], 168 [35ClC6H4CHCS, 100]; Anal.
Calcd for C25H16BrCl2N3OS: C, 53.88; H, 2.89; N, 7.54.
Found: C, 53.72; H, 2.45; N, 7.41.
1
2-[3-(4-Bromophenyl)-5-(4-chlorophenyl)-4,5-dihydro-
1H-pyrazol-1-yl]-5-(2-methoxybenzylidene)-1,3-
thiazol-4(5H)-one (3c)
Yield 36 %; mp 290–291 °C (DMF); IR (cm-1): 2931,
2831 (CH-aliphatic), 1681 (C=O); 1H NMR (300 MHz,
DMSO-d6) d ppm: 3.45 (dd, 1H, HA, JAB = 18.3 Hz,
JAX = 4.5 Hz), 3.87 (s, 3H, OCH3), 4.09 (dd, 1H, HB,
JAB = 18.3 Hz, JBX = 11.4 Hz), 5.87 (dd, 1H, Hx,
JAX = 4.5 Hz, JBX = 11.4 Hz), 7.10–7.81 (m, 12H, Ar–
H), 7.89 (s, 1H, =CH); MS m/z [ %]: 555 [(M?4)?, 2.46],
553 [(M?2)?, 7.87], 551 [M?, 5.41], 524 [M?4-CH3O,
31.49], 522 [M?2-CH3O, 100], 520 [M-CH3O, 73.83], 183
[81BrC6H4CN, 4.36], 181 [79BrC6H4CN, 5.08], 164 [CH3
OC6H4CHCS, 94.43]; Anal. Calcd for C26H19BrClN3O2S:
C, 56.48; H, 3.46; N, 7.60. Found: C, 56.63; H, 3.69;
N, 7.29.
General procedure for the synthesis of 5-arylidene-2-
(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-1,3-thiazol-
4(5H)-ones 3a–3l
A mixture of the respective 2a and 2b(2 mmol), chloroacetic
acid (0.19 g, 2 mmol), anhydrous sodium acetate (0.17 g,
2 mmol), and the appropriate aromatic aldehyde (2.4 mmol)
in glacial acetic acid (10 mL) was heated under reflux for
15 h. The reaction mixture was cooled and poured gradually
into crushed ice. The resulting solid product was filtered and
crystallized from a suitable solvent.
2-[3-(4-Bromophenyl)-5-(4-chlorophenyl)-4,5-dihydro-
1H-pyrazol-1-yl]-5-(4-methoxybenzylidene)-1,3-
thiazol-4(5H)-one (3d)
5-Benzylidene-2-[3-(4-bromophenyl)-5-(4-
chlorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]-1,3-
thiazol-4(5H)-one (3a)
Yield 56 %; mp 246–247 °C (AcOH); IR (cm-1): 2974,
2931 (CH-aliphatic), 1716 (C=O); 1H NMR (300 MHz,
DMSO-d6) d ppm: 3.44 (dd, 1H, HA, JAB = 18.0 Hz,
JAX = 4.0 Hz), 3.80 (s, 3H, OCH3), 4.01 (dd, 1H, HB,
JAB = 18.0 Hz, JBX = 11.0 Hz), 5.92 (dd, 1H, Hx,
JAX = 4.0 Hz, JBX = 11.0 Hz), 7.11–7.80 (m, 12H, Ar–H),
7.90 (s, 1H, =CH); MS m/z [ %]: 555 [(M?4)?, 23.49], 553
[(M?2)?, 78.68], 551 [M?, 55.99], 164 [CH3OC6H4CHCS,
100]; Anal. Calcd for C26H19BrClN3O2S: C, 56.48; H, 3.46;
N, 7.60. Found: C, 56.12; H, 3.40; N, 7.81.
Yield 66 %; mp 288–289 °C (DMF); IR (cm-1): 2951, 2850
(CH-aliphatic), 1712 (C=O); H NMR (300 MHz, DMSO-
1
d6) d ppm: 3.46 (dd, 1H, HA, JAB = 18.3 Hz, JAX
=
3.9 Hz), 4.14 (dd, 1H, HB, JAB = 18.3 Hz, JBX = 11.4 Hz),
5.90 (dd, 1H, Hx, JAX = 3.9 Hz, JBX = 11.4 Hz), 7.31–7.84
(m, 14H, Ar–H and =CH); MS m/z [ %]: 525 [(M?4)?,
20.39], 523 [(M?2)?, 42.48], 521 [M?, 46.72], 342
[M?2-79BrC6H4CN, 39.42], 340 [M-79BrC6H4CN, 100];
Anal. Calcd for C25H17BrClN3OS: C, 57.43; H, 3.28; N,
8.04. Found: C, 57.02; H, 3.45; N, 8.41.
2-[3-(4-Bromophenyl)-5-(4-chlorophenyl)-4,5-dihydro-
1H-pyrazol-1-yl]-5-(2-nitrobenzylidene)-1,3-thiazol-
4(5H)-one (3e)
2-[3-(4-Bromophenyl)-5-(4-chlorophenyl)-4,5-dihydro-
1H-pyrazol-1-yl]-5-(4-chlorobenzylidene)-1,3-thiazol-
4(5H)-one (3b)
Yield 60 %; mp 265–266 °C (DMF); IR (cm-1): 2950,
2855 (CH-aliphatic), 1701 (C=O), 1539, 1334 (NO2); H
1
NMR (300 MHz, DMSO-d6) d ppm: 3.48 (dd, 1H, HA,
JAB = 18.4 Hz, JAX = 4.2 Hz), 4.12 (dd, 1H, HB,
JAB = 18.4 Hz, JBX = 11.8 Hz), 5.90 (dd, 1H, Hx,
Yield 43 %; mp 250–251 °C (DMF); IR (cm-1): 2974,
2927 (CH-aliphatic), 1685 (C=O); 1H NMR (300 MHz,
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Med Chem Res (2013) 22:1021–1027
1025
JAX = 4.2 Hz, JBX = 11.8 Hz), 7.31–7.84 (m, 12H, Ar–
H), 7.94 (s, 1H, =CH); MS m/z [ %]: 570 [(M?4)?, 2.34],
568 [(M?2)?, 7.59], 566 [M?, 8.17], 387 [M?
2-79BrC6H4CN, 9.13], 385 [M-79BrC6H4CN, 44.75], 183
[81BrC6H4CN, 6.25], 181 [79BrC6H4CN, 7.56], 179
[NO2C6H4CHCS, 40.64], 103 [100]; Anal. Calcd for
C25H16BrClN4O3S: C, 52.88; H, 2.84; N, 9.87. Found: C,
52.62; H, 3.05; N, 9.75.
[M?4-35ClC6H4CN, 2.49], 376 [M?2-35ClC6H4CN,
14.73], 374 [M-35ClC6H4CN, 23.30], 170 [37ClC6H4
CHCS, 42.44], 168 [35ClC6H4CHCS, 100], 139 [37ClC6H4
CN, 3.77], 137 [35ClC6H4CN, 8.69]; Anal. Calcd for
C25H16Cl3N3OS: C, 58.55; H, 3.14; N, 8.19. Found: C,
58.36; H, 3.49; N, 8.57.
2-[3,5-Bis(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]-
5-(2-methoxybenzylidene)-1,3-thiazol-4(5H)-one (3i)
2-[3-(4-Bromophenyl)-5-(4-chlorophenyl)-4,5-dihydro-
1H-pyrazol-1-yl]-5-(3-nitrobenzylidene)-1,3-thiazol-
4(5H)-one (3f)
Yield 58 %; mp 281–282 °C (AcOH); IR (cm-1): 2974,
2835 (CH-aliphatic), 1685 (C=O); 1H NMR (300 MHz,
DMSO-d6) d ppm: 3.42 (dd, 1H, HA, JAB = 18.6 Hz,
JAX = 4.0 Hz), 3.87 (s, 3H, OCH3), 4.10 (dd, 1H, HB,
JAB = 18.6 Hz, JBX = 11.0 Hz), 5.90 (dd, 1H, Hx,
JAX = 4.0 Hz, JBX = 11.0 Hz), 7.12–7.89 (m, 12H, Ar–
H), 7.91 (s, 1H, =CH); MS m/z [ %]: 511 [(M?4)?, 0.6],
509 [(M?2)?, 3.90], 507 [M?, 5.02], 480 [M?4-CH3O,
15.14], 478 [M?2-CH3O, 70.36], 476 [M-CH3O, 100], 164
[CH3OC6H4CHCS, 60.69]; Anal. Calcd for C26H19
Cl2N3O2S: C, 61.42; H, 3.77; N, 8.26. Found: C, 61.32; H,
3.76; N, 8.53.
Yield 74 %; mp 294–295 °C (DMF); IR (cm-1): 2939,
2830 (CH-aliphatic), 1693, (C=O), 1527, 1350 (NO2); H
1
NMR (300 MHz, DMSO-d6) d ppm: 3.49 (dd, 1H, HA,
JAB = 18.6 Hz, JAX = 4.2 Hz), 4.17 (dd, 1H, HB, JAB
=
18.6 Hz, JBX = 9.4 Hz), 5.91 (dd, 1H, Hx, JAX = 4.2 Hz,
JBX = 9.4 Hz), 7.32–8.28 (m, 12H, Ar–H), 8.46 (s, 1H,
=CH); MS m/z [ %]: 570 [(M?4)?, 5.98], 568 [(M?2)?,
12.32], 566 [M?, 7.95], 387 [M?2-79BrC6H4CN, 24.38],
385 [M-79BrC6H4CN, 82.01] 183 [81BrC6H4CN, 17.22],
181 [79BrC6H4CN, 18.82], 179 [NO2C6H4CHCS, 100];
Anal. Calcd for C25H16BrClN4O3S: C, 52.88; H, 2.84; N,
9.87. Found: C, 52.47; H, 2.55; N, 9.60.
2-[3,5-Bis(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]-
5-(4-methoxybenzylidene)-1,3-thiazol-4(5H)-one (3j)
5-Benzylidene-2-[3,5-bis(4-chlorophenyl)-4,5-dihydro-
Yield 43 %; mp 250–251 °C (AcOH); IR (cm-1): 2974,
2927 (CH-aliphatic), 1701 (C=O); 1H NMR (300 MHz,
DMSO-d6) d ppm: 3.40 (dd, 1H, HA, JAB = 18.0 Hz,
JAX = 4.0 Hz), 3.80 (s, 3H, OCH3), 4.10 (dd, 1H, HB,
JAB = 18.0 Hz, JBX = 11.0 Hz), 5.90 (dd, 1H, Hx,
JAX = 4.0 Hz, JBX = 11.0 Hz), 7.30–7.80 (m, 12H, Ar–
H), 7.90 (s, 1H, =CH); MS m/z [ %]: 511 [(M?4)?, 5.99],
509 [(M?2)?, 3.90], 507 [M?, 0.6], 164 [CH3
OC6H4CHCS, 100]; Anal. Calcd for C26H19Cl2N3O2S:
C, 61.42; H, 3.77; N, 8.26. Found: C, 61.54; H, 3.85;
N, 8.18.
1H-pyrazol-1-yl]-1,3-thiazol-4(5H)-one (3g)
Yield 32 %; mp 257–258 °C (AcOH); IR (cm-1): 2954,
2931 (CH-aliphatic), 1693 (C=O); 1H NMR (300 MHz,
DMSO-d6) d ppm: 3.48 (dd, 1H, HA, JAB = 18.5 Hz,
JAX = 4.0 Hz), 4.12 (dd, 1H, HB, JAB = 18.5 Hz,
JBX = 11.2 Hz), 5.91 (dd, 1H, Hx, JAX = 4.0 Hz,
JBX = 11.2 Hz), 7.31–7.67 (m, 13H, Ar–H), 7.90 (s, 1H,
=CH); MS m/z [ %]: 481 [(M?4)?, 0.93], 479 [(M?2)?,
4.52], 477 [M?, 8.11], 342 [M?2-35ClC6H4CN, 6.71], 340
[M-35ClC6H4CN, 15.78], 134 [C6H5CHCS, 100]; Anal.
Calcd for C25H17Cl2N3OS: C, 62.77; H, 3.58; N, 8.78.
Found: C, 62.56; H, 3.45; N, 8.64.
2-[3,5-Bis(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-
yl]-5-(2-nitrobenzylidene)-1,3-thiazol-4(5H)-one (3k)
2-[3,5-Bis(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-
Yield 53 %; mp 255–256 °C (AcOH); IR (cm-1): 2981,
2927 (CH-aliphatic), 1689 (C=O), 1543, 1338 (NO2); H
1
yl]-5-(4-chlorobenzylidene)-1,3-thiazol-4(5H)-one (3h)
NMR (300 MHz, DMSO-d6) d ppm: 3.56 (dd, 1H, HA,
JAB = 18.4 Hz, JAX = 4.3 Hz), 4.15 (dd, 1H, HB,
JAB = 18.4 Hz, JBX = 11.2 Hz), 5.92 (dd, 1H, Hx,
JAX = 4.3 Hz, JBX = 11.2 Hz), 7.30–8.16 (m, 12H, Ar–
H), 8.19 (s, 1H, =CH); MS m/z [ %]: 524 [(M?2)?, 0.33],
522 [M?, 0.46], 387 [M?2-35ClC6H4CN, 8.13], 385
[M-35ClC6H4CN, 16.87], 179 [NO2C6H4CHCS, 35.48], 57
[100]; Anal. Calcd for C25H16Cl2N4O3S: C, 57.37; H, 3.08;
N, 10.70. Found: C, 57.04; H, 3.17; N, 10.41.
Yield 37 %; mp 289–290 °C (AcOH); IR (cm-1): 2974,
2924 (CH-aliphatic), 1681 (C=O); 1H NMR (300 MHz,
DMSO-d6) d ppm: 3.41 (dd, 1H, HA, JAB = 18.0 Hz,
JAX = 4.0 Hz), 4.10 (dd, 1H, HB, JAB = 18.0 Hz,
JBX = 11.0 Hz), 5.90 (dd, 1H, Hx, JAX = 4.0 Hz,
JBX = 11.0 Hz), 7.30–7.88 (m, 12H, Ar–H), 7.91 (s, 1H,
=CH); MS m/z [ %]: 517 [(M?6)?, 1.05], 515 [(M?4)?,
4.08], 513 [(M?2)?, 7.81], 511 [M?, 10.08], 378
123

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Med Chem Res (2013) 22:1021–1027
ꢀ
ꢁ
m
2-[3,5-Bis(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-
½Dꢃ
% Cell viability ¼ ð100 ꢁ RÞ ꢂ 1 ꢁ
þ R
m
Kdm þ ½Dꢃ
yl]-5-(3-nitrobenzylidene)-1,3-thiazol-4(5H)-one (3l)
Yield 42 %; mp [ 300 °C (DMF); IR (cm-1): 2958, 2935
(CH-aliphatic), 1693 (C=O), 1527, 1350 (NO2); H NMR
where R is the residual unaffected fraction (the resistance
fraction), [D] is the drug concentration used, Kd is the drug
concentration that produces a 50 % reduction of the max-
imum inhibition rate and m is a Hill-type coefficient. IC50
was defined as the drug concentration required to reduce
fluorescence to 50 % of that of the control (i.e., Kd = IC50
when R = 0 and Emax = 100 - R) (Al-Abd et al., 2008).
1
(300 MHz, DMSO-d6) d ppm: 3.57 (dd, 1H, HA,
JAB = 18.6 Hz, JAX = 4.3 Hz), 4.14 (dd, 1H, HB,
JAB = 18.6 Hz, JBX = 10.6 Hz), 5.92 (dd, 1H, Hx,
JAX = 4.3 Hz, JBX = 10.6 Hz), 7.33–8.29 (m, 12H, Ar–
H), 8.47 (s,1H, = CH); MS m/z [ %]: 526 [(M?4)?, 3.08],
524 [(M?2)?, 23.06], 522 [M?, 31.30], 387 [M?
2-35ClC6H4CN, 41.44], 385 [M-35ClC6H4CN, 82.78], 179
[NO2C6H4CHCS, 100]; Anal. Calcd for C25H16Cl2N4O3S:
C, 57.37; H, 3.08; N, 10.70. Found: C, 57.56; H, 3.04; N,
11.01.
Acknowledgments The authors are grateful to Dr. Ashraf Bahey
El-Deen Abd El-Naeem, Professor of Pharmacology, Faculty of
Pharmacy, Ain Shams University, for carrying out antiproliferative
activity.
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