Synthesis of novel pyrazole and pyrimidine derivatives bearing Sulfonamide moiety as antitumor and radiosensitizing agents

Article abstract of DOI:10.1007/s00044-011-9653-x

Several novel pyrazole 10-16 and pyrimidine 17-19 derivatives bearing Sulfonamide moieties were synthesized in order to study their antitumor activity. The synthesized compounds were characterized by elemental analysis, IR, ¹H-NMR, and mass spe

Full text of DOI:10.1007/s00044-011-9653-x

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2012) 21:1376–1383
DOI 10.1007/s00044-011-9653-x
ORIGINAL RESEARCH
Synthesis of novel pyrazole and pyrimidine derivatives bearing
sulfonamide moiety as antitumor and radiosensitizing agents
•
Mostafa M. Ghorab Fatma A. Ragab
•
•
Helmy I. Heiba Hanan A. Youssef
•
Marwa G. El-Gazzar
Received: 29 March 2010 / Accepted: 26 April 2011 / Published online: 8 May 2011
Ó Springer Science+Business Media, LLC 2011
Abstract Several novel pyrazole 10–16 and pyrimidine
17–19 derivatives bearing Sulfonamide moieties were
synthesized in order to study their antitumor activity. The
synthesized compounds were characterized by elemental
analysis, IR, 1H-NMR, and mass spectral data, then
screened as antitumor agents against human tumor liver
and breast cell lines (HEPG2 and MCF7). All the tested
compounds were more potent than the reference drug
doxorubicin on human liver (HEPG2) cell line, while on
human breast cancer (MCF7) cell line, they were less
potent than the reference drug. Additionally, some of the
synthesized compounds were evaluated for their ability to
enhance the cell killing effect of c-radiation.
Introduction
Nitrogen heterocycles are of special interest because they
constitute an important class of natural and non-natural
products, many of which exhibit useful biological activities.
Pyrazoles and their derivatives exhibit a broad spectrum of
biological activities such as antimicrobial (Mitchell et al.,
2008), anti-inflammatory (Gokhan et al., 2007), and anti-
tumor activities (Lin et al., 2007). With growing application
on their synthesis and bioactivity, chemists and biologists in
recent years have directed considerable attention on the
research of pyrazole derivatives. Pyrimidines are of chem-
ical and pharmacological interest and compounds contain-
ing the pyrimidine ring system have been shown to possess
antibacterial (Deshmukh et al., 2009), antifungal (Gholap
et al., 2008), antimalarial (Azas et al. 2003), anticonvulsant
(Said et al. 2009), and antitumor activities (Noll et al.,
2009). Some are valuable drugs for the treatment of acute
leukemia in children and adult granulocytic leukemia (Noll
et al., 2009). on the other hand, sulfonamides are known to
possess several pharmacological activities including anti-
bacterial (Ghorab et al., 2004), antiviral (Supuran et al.,
2004), antifungal (Ezabadi et al., 2008), hypoglycemic
(Anjaneyulu et al., 1980), diuretic (Jaiswal et al., 2004), and
anticancer activities (Ghorab et al., 2006; Ghorab et al.,
2007, 2009; Abou El Ella et al., 2008; Ismail et al., 2006),
they exhibit their anticancer activities through different
mechanisms of action the most important is that they act as
carbonic anhydrase inhibitors (Supuran and Scozzafava,
2007); (Temperini et al., 2010). Due to our interest in the
development of novel antitumor agents, in this study, we
report the synthesis of some new pyrazole and pyrimidine
derivatives brearing a sulfonamide moiety in order to study
their SAR and hoping that these new compounds might
show significant anticancer activity.
Keywords Pyrazole Á Pyrimidine Á Sulfonamide Á
Antitumor activity Á Radiation
M. M. Ghorab (&)
Medicinal, aromatic and poisonous plants research center
(MAPPRC), College of pharmacy, King Saud University,
P.O. Box 2457, Riyadh 11451, Saudi Arabia
e-mail: mmsghorab@yahoo.com
F. A. Ragab Á H. A. Youssef
Department of Pharmaceutical Chemistry,
Faculty of Pharmacy, Cairo University, Cairo, Egypt
H. I. Heiba Á M. G. El-Gazzar
Department of Drug Radiation Research, National Center
for Radiation, Research and Technology, Nasr City, Cairo, Egypt
123

Med Chem Res (2012) 21:1376–1383
Results and discussion
Synthesis
1377
derivatives 10, 14. Their IR spectra showed disappearance
of CN bands and presence of forked bands characteristic
for NH2, while their mass spectra revealed molecular ion
peaks at 357 and 408, respectively. On the other hand
interaction of compounds 5–9 with phenyl hydrazine in
dioxane as a solvent yielded the corresponding pyrazole
derivatives 11–13, 15, 16, their IR spectra showed the
disappearance of CN bands and presence of forked bands
characteristic for NH2 along with bands for C=O for
compounds 11, 13 and 16, while their mass spectra
revealed molecular ion peaks at 434, 462, 463, 484 and
487, respectively. Reaction of compounds 4 or 6 with
phenyl isothiocyanate in NaOH/ethanol gave the corre-
sponding pyrimidine derivatives 17 or 18, respectively,
their IR spectra showed the presence of C=O bands, while
their mass spectra showed molecular ion peaks at 461 and
490, respectively. Finally, reaction of sulfonamide deriva-
tive 9 with thiourea yielded the pyrimidine derivative 19.
Its IR spectrum showed disappearance of CN bands, while
its mass spectrum showed molecular ion peak at 453.
In this work, the reactivity of different sulfonamides
1–3 (sulfapyridine, sulfadimidine, sulfaquinoxaline) with
active methylenes (malononitril and ethylcyanoacetate)
was studied. The obtained sulfonamide derivatives 4–9,
respectively, were identified by elemental and spectral
data. IR spectra of compounds 4, 6, 8, showed the presence
of characteristic CN bands, IR spectra of compounds 5, 7,
9, exhibited the presence of CN and ester bands, while their
NMR spectra showed the presence of triplet and quartet
signals characteristic of ester group. Due to the biological
importance of pyrazole and pyrimidine rings as anticancer
agents, sulfonamide derivatives 4–9 were reacted with
different nucleophiles in order to obtain biologically active
pyrazole and pyrimidine derivatives bearing sulfonamide
moieties. Thus, interaction of sulfonamide derivatives 4, 8
with hydrazine hydrate yielded the corresponding pyrazole
123

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Med Chem Res (2012) 21:1376–1383
cell line with IC50 5.1, 6.98, 7.78, 6.71, and 5.63 lM.
These results attract the attention of the possible use of
pyrazole, pyrimidine and sulfonamide derivatives espe-
cially on liver tumors.
R2
R3
X
Y
1
–
–
–
–
2
–
–
–
–
3
–
–
–
–
4
–
–
CN
CN
CN
CN
CN
CN
–
CN
Radiosensitizing activity
5
–
–
COOEt
6
–
–
CN
The rationale for combining chemotherapy and radiother-
apy is based mainly on two ideas, one being spatial
cooperation, which is effective if chemotherapy is suffi-
ciently active to eradicate subclinical metastases and if the
primary local tumor is effectively treated by radiotherapy.
In this regard, no interaction between radiotherapy and
chemotherapy is required. The other idea is the enhance-
ment of radiation effects. Cytotoxic agents can enhance
radiation effects by direct enhancement of the initial radi-
ation damage by incorporating drugs into DNA, inhibiting
cellular repair, accumulating cells in a radiosensitive phase
or eliminating radioresistant phase cells, eliminating hyp-
oxic cells or inhibiting the accelerated repopulation of
tumor cells. Virtually, all chemotherapeutic agents have the
ability to sensitize cancer cells to the lethal effects of
ionizing radiation (Nishimura, 2004). Consequently, the
ability of the tested compounds 11, 12, 14, 16 and 18, to
enhance the cell killing effect of c-irradiation was studied.
From Tables 2 and 3, we can observe that the effect of
radiation alone was not significant when compared to
control group which contains the cell lines without radia-
tion or drug. On the other hand, the surviving fraction of
the tested compounds decreased significantly from the
control after being subjected to radiation which indicates
the synergism due to combining drugs with radiation.
7
–
–
COOEt
8
–
–
CN
9
–
–
COOEt
10
11
12
13
14
15
16
17
18
H
Ph
Ph
Ph
H
Ph
Ph
–
NH
O
NH
O
NH
NH
O
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
In vitro anticancer screening
Doxorubicin, the reference drug used in this study is one of
the most effective antitumor agents used to produce
regressions in acute leukemia’s Hodgkin’s disease, and
other lymphomas. The relationship between surviving
fraction and drug concentration was plotted; the response
parameters calculated was IC50 value, which corresponds
to the compound concentration causing 50% mortality in
net cells (Table 1). From Table 1, we can observe that all
the tested compounds were found to be more potent than
Doxorubicin on HEPG2 cell line with IC50 3.49, 3.76, 3.22,
3.21, and 3.49 lM, respectively. On the other hand, these
compounds were less potent than Doxorubicin on MCF7
Conclusion
From the above results, we can conclude that administra-
tion of the tested compounds on human liver and breast
(HEPG2 and MCF7)) cell lines showed promising anti-
cancer activity, while, combining these compounds with
radiation at the same concentrations enhances their activity
which demonstrates the importance of the combination
therapy for the patients with cancer to decrease the side
effects of both drugs and radiation.
Table 1 In-vitro anticancer screening of compounds 11, 12, 14, 16
and 18 against human liver cell line (HEPG2) and human breast cell
line (MCF7)
a,b
Compound
Cytotoxicity (IC50
)
(lM)
HEPG2
MCF7
11
3.49
3.76
3.22
3.21
3.49
5.23
5.1
12
6.98
7.78
6.71
5.63
3.22
14
Experimental
16
18
Synthesis
Doxorubicin
a
Melting points are uncorrected and were determined on a
Stuart melting point apparatus (Stuart Scientific, Redhill,
UK). Elemental analysis (C, H, N) were performed on
IC50 compounds concentration required to inhibit tumor cell pro-
liferation by 50%
b
Values are means of three experiments
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Med Chem Res (2012) 21:1376–1383
1379
Table 2 Statistical analysis of the results of in vitro cytotoxic activity of compounds 11, 12, 14, 16, 18 against human liver cell line (HEPG2)
Cpd.no Control (cells only) Control (radiation)
Drug (lM)
5
12.5
25
40
Means SE (% change)a
11
12
14
16
18
1.4152 0.02606
(100%)
1.24 0.08145ns
(12.38%)
1.2303 0.04683ns 0.788 0.1095*
(18.73%) (47.94%)
1.2303 0.04683ns 1.239 0.1372ns
(18.73%) (18.15%)
0.8563 0.1775*
(39.49%)
0.597 0.02107*
(57.82%)
0.5427 0.04557* 0.388 0.006658* 0.2917 0.01417*
0.4673 0.09998* 0.279 0.01559*
(66.9%) (80.2%)
1.5139 0.03894
(100%)
(64.14%)
(74.3%)
0.4053 0.01565* 0.214 0.008505*
(73.2%) (85.8%)
0.3613 0.05197* 0.312 0.02887*
(80.7%)
1.5139 0.03894
(100%)
0.677 0.03889*
(55.27%)
1.5139 0.03894
(100%)
1.2303 0.04683ns 0.9027 0.04628* 0.5247 0.1039*
(18.73%)
1.2022 0.03297ns 1.221 0.05677ns
(21.2%) (19.98%)
(40.36%)
(65.3%)
(76.15%)
(79.39%)
1.526 0.05680
(100%)
0.7763 0.1749*
(49.12%)
0.531 0.08071*
(62.2%)
0.311 0.007767*
(79.6%)
Each value is the mean of three values SE
a
Percentage of change from control group
ns
Non- significant difference from control group at P \ 0.05
* Significant difference from control group at P \ 0.05
Table 3 Statistical analysis of the results of in vitro cytotoxic activity of compounds 11, 12, 14, 16, 18 against human liver cell line (HEPG2)
after irradiation
Cpd.no Control (cells only) Control (radiation)
Drug Irradiated (lM)
5
12.5
25
40
Means SE (% change)a
11
12
14
16
18
1.4152 0.02606
(100%)
1.24 0.08145ns
(12.38%)
1.2303 0.04683ns 0.368 0.07573*
0.5367 0.03844* 0.271 0.1209*
0.3297 0.09303* 0.1153 0.02298*
(76.7%) (91.8%)
0.2097 0.05057* 0.1073 0.01477* 0.1753 0.04474*
(86%) (92.9%) (88.4%)
1.2303 0.04683ns 0.7023 0.01202* 0.4987 0.03263* 0.2933 0.05292* 0.1777 0.01040*
(62.1%)
(80.8%)
1.5139 0.03894
(100%)
(18.73%) (75.69%)
1.5139 0.03894
(100%)
(18.73%)
(53.6%)
(67%)
(80.6%)
(88.2%)
1.5139 0.03894
(100%)
1.2303 0.04683ns 0.6493 0.03684* 0.3353 0.05942* 0.097 0.01222*
0.1737 0.008988*
(88.5%)
(18.73%)
1.2022 0.03297ns 0.8057 0.03848* 0.445 0.02950*
(21.2%) (47.2%) (70.8%)
(57.1%)
(77.8%)
(93.5%)
1.526 0.05680
(100%)
0.342 0.07778*
(77.5%)
0.1927 0.004096*
(87.3%)
Each value is the mean of three values SE
a
Percentage of change from control group
ns
Non- significant difference from control group at P \ 0.05
* Significant difference from control group at P \ 0.05
Perkin-Elmer 2400 analyser (Perkin-Elmer, Norwalk, CT,
USA) at the microanalytical laboratories of the Faculty of
Science, Cairo University. Analysis of all compounds was
within 0.4% of the theoretical values. The IR spectra
(KBr) were measured on Shimadzu IR 110 spectropho-
tometer (Shimadzu, Koyoto, Japan), 1H-NMR spectra were
obtained on a Bruker proton NMR-Avance 300 (300 MHz)
(Bruker, Munich, Germany), in DMSO-d6 as a solvent,
using tetramethylsilane (TMS) as internal standard. Mass
spectra were run on HP Model MS-5988 (Hewlett Packard,
Palo, Alto, California, USA). All reactions were monitored
by thin layer chromatograph (TLC) using precoated Alu-
minium sheets Silica gel Merck 60 F254 and were visu-
alized by UV lamp (Merck, Darmstadt, Germany).
4-(2,2-Dicyanovinylamino)-N-(substituted)-
benzenesulfonamides (4, 6, 8)
A mixture of sulfonamide (sulfapyridine, sulfadimidine or
sulfaquinoxaline) (0.01 mol), malononitrile (0.01 mol),
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Med Chem Res (2012) 21:1376–1383
triethylorthoformate (0.01 mol), and acetic acid (1 ml) in
methanol (30 ml) was refluxed for 5 h, the reaction mixture
was filtered, the filtered solid was crystallized from ethanol
to give 4, 6, 8, respectively.
(C=O), 1312, 1158 (SO2). 1H-NMR DMSO-d6 (ppm):
1.2[t, 3H, CH3], 4.1[q, 2H, CH2], 5.9[s, 2H, CH ? NH],
6.5, 7,5[2d, 4H, Ar–H AB system], 6.8, 7.8[2d, 2H, CH-
pyridine], 7.2-7.6[m, 2H, CH-pyridine], 8.4[s, 1H,
SO2NH]. Anal. Calcd. For C17H16N4O4S: C, 54.83; H,
4.33; N, 15.04. Found: C, 55.10; H, 4.50; N, 15.40.
4-(2,2-Dicyanovinylamino)-N-(pyridin-2-
yl)benzensulfonamide (4)
4-(2-Cyano-2-ethylvinylamino)-N-(4,6-dimethylpyrimidin-
2-yl)benzene-sulfonamide (7)
Yield%: 55, m.p. = 189–190°C, IR, cm-1: 3412, 3308
(NH), 3038 (CH arom.), 2955, 2867 (CH aliph.), 2216 (CN),
1333, 1146 (SO2). 1H DMSO d6 (ppm): 5.9[s, 2H,
CH ? NH], 6.5, 7.5[2d, 4H, Ar–H AB system], 6.8, 7.6[2t,
2H, 2CH-pyridine], 7.09, 8.09[2d, 2H, 2CH-pyridine],
10.9[s, 1H, SO2NH]. Anal. Calcd. For C15H11N5O2S: C,
55.38; H, 3.41; N, 21.53. Found: C, 54.10; H, 3.80; N, 21.20.
Yield%: 70, m.p.: 138-1400, IR, cm-1: 3292, 3190 (NH),
3086 (CH arom.), 2955, 2867 (CH aliph.), 2214 (CN), 1746
(C=O), 1321, 1136 (SO2). 1H-NMR DMSO-d6 (ppm):
1.2[t, 3H, CH3], 1.9, 2.5[2 s, 6H, 2CH3], 4.2[q, 2H, CH2],
6.7[s, 1H, CH-pyrimidine], 7.3, 7.4[d, 1H, CH], 7.56[s, 1H,
NH], 7.5, 7.9[2d, 4H, Ar–H AB system], 8.6[s, 1H,
SO2NH]. Anal. Calcd. For C18H19N5O4S: C, 53.85; H,
4.77; N, 17.45. Found: C, 54.20, H, 4.40; N, 17.00.
4-(2,2-Dicyanovinylamino)-N-(4,6-dimethylpyrimidin-2-
yl)benzene-sulfonamide (6)
Yield%: 60, m.p. = 214–216°C, IR, cm-1: 3336, 3238
(NH), 3090 (CH arom.), 2977, 2834 (CH aliph.), 2218
1
(CN), 1310, 1158 (SO2). H DMSO d6 (ppm): 1.9, 2.5[2s,
4-(2-Cyano-2-ethylvinylamino)-N-(quinoxalin-2-
yl)benzene-sulfonamide (9)
6H, 2CH3], 6.6, 6.7[d, 1H, CH], 5.9[s, 1H, CH-pyrimidine],
6.7[s, 1H, NH], 7.6, 7.9[2d, 4H, Ar–H], 8.5[s, 1H, SO2NH].
Anal. Calcd. For C16H14N6O2S: C, 54.23; H, 3.98; N,
23.71. Found: C, 53.80; H, 3.70; N, 23.50.
Yield%: 50, m.p.: 248–249°C, IR, cm-1: 3360, 3250 (NH),
3072 (CH arom.), 2967, 2878 (CH aliph.), 2216 (CN), 1686
(C=O), 1332, 1145 (SO2). 1H-NMR DMSO-d6 (ppm):
1.2[t, 3H, CH3], 4.2[q, 2H, CH2], 6.2, 6.3[d, 1H, CH],
6.5[s, 1H, NH], 7.6–7.7[m, 4H, Ar–H], 7.9, 8.06[2d, 4H,
Ar–H AB system], 8.5[s, 1H, CH-quinoxalin], 8.6[s, 1H,
SO2NH]. Anal. Calcd. For C20H17N5O4S: C, 56.73; H,
4.05; N, 16.54. Found: C, 56.40; H, 4.30; N, 16.10.
4-(2,2-Dicyanovinylamino)-N-(quinoxalin-2-
yl)benzensulfonamide (8)
Yield%: 65, m.p. = 236, 238°C, IR, cm-1: 3438, 3360
(NH), 3074 (CH arom.), 2984, 2895 (CH aliph.), 2220
1
(CN), 1320, 1158 (SO2). H DMSO d6 (ppm): 6.03, 6.1[d,
4-((3-Amino-5-substituted-1H-pyrazol-4-
ylidene)methylamino)-N-(substituted)benzene-sulfonamide
(10–16)
1H, CH], 6.5[s, 1H, NH],7,6[m, 4H, Ar–H], 7.7, 7.9[2d,
4H, Ar–H AB system], 8.5[s, 1H, CH quinoxaline], 11.5[s,
1H, SO2NH]. Anal. Calcd. For C18H12N6O2S: C, 57.44; H,
3.21; N, 22.33. Found: C, 57.80; H, 3.40; N, 22.50.
Compounds 4–9 (0.01 mol) were mixed with either
hydrazine hydrate (0.01 mol) or phenyl hydrazine
(0.01 mol) in dioxane (20 ml) and refluxed for 5 h, the
reaction mixture was cooled, poured onto ice water. The
precipitated solid products were filtered and crystallized
from methanol to give compounds 10–16.
4-(2-Cyano-2-ethylvinylamino)-N-
(substituted)benzenesulfonamides (5, 7, 9)
A mixture of sulfonamide (sulfapyridine, sulfadimidine
or sulfaquinoxaline) (0.01 mol), ethyl cyanoacetate (0.01
mol), triethylorthoformate (0.01 mol) and acetic acid (1 ml)
in methanol (30 ml) was refluxed for 5 h, the reaction
mixture was filtered, the filtered solid was crystallized from
ethanol to give 5, 7, 9, respectively.
4-((3-Amino-5-imino-1H-pyrazol-4-ylidene)methylamino)-
N-(pyridin-2-yl)benzene-sulfonamide (10)
Yield%: 55, m.p.: 112–114°C, IR, cm-1: 3424, 3373, 3254
(NH, NH2), 3022 (CH arom.), 2989, 2845 (CH aliph.),
1315, 1143 (SO2). MS (m/z, RI%): 357 (M?, 10%), 360
(60%), 230 (77%), 92 (86%), 90 (100%). Anal. Calcd. For
C15H15N7O2S: C, 50.41; H, 4.23; N, 27.43. Found: C,
50.82; H, 4.67; N, 27.68.
4-(2-Cyano-2-ethylvinylamino)-N-(pyridinyl-2-
yl)benzenesulfonamide (5)
Yield%: 66, m.p.: 149–151°C, IR, cm-1: 3312, 3238 (NH),
3050 (CH arom.), 2966, 2890 (CH aliph.), 2216 (CN), 1746
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Med Chem Res (2012) 21:1376–1383
1381
4-((3-Amino-5-oxo-1-phenyl-1H-pyrazol-4-
ylidene)methylamino)-N-(pyridin-2-yl)-
benzenesulfonamide (11)
4-((3-Amino-5-oxo-1-phenyl-1H-pyrazol-4-
ylidene)methylamino)-N-(quinoxalin-2-yl)-
benzenesulfonamide (16)
Yield%: 70, m.p.: 72–74°C, IR, cm-1: 3267, 3232, 3167
(NH, NH2), 3120 (CH arom.), 2987, 2864 (CH aliph.),
1686 (C=O), 1310, 1146 (SO2). MS (m/z, RI%): 434 (M?,
10.2%), 321 (67%), 145 (78%), 123(100%). Anal. Calcd.
For C21H18N6O3S: C, 58.05; H, 4.18; N, 19.34. Found: C,
58.34; H, 4.56; N, 19.67.
Yield%: 66, m.p.: 88–90°C, IR, cm-1: 3222, 3232, 3156
(NH, NH2), 3020 (CH arom.), 2995, 2833 (CH aliph.),
1680 (C=O), 1333, 1176 (SO2). MS (m/z, RI%): 485 (M?,
12.2%), 234 (80%), 157 (88%), 123(100%). Anal. Calcd.
For C24H19N7O3S: C, 59.37; H, 3.94; N, 20.19. Found: C,
59.65; H, 4.21; N, 20.50.
4-((3-Amino-5-imino-1-phenyl-1H-pyrazol-4-
ylidene)methylamino)-N-(4,6-dimethyl-pyrimidin-2-
yl)benzenesulfonamide (12)
4-(5-Cyano-4-oxo-3-phenyl-2-thioxo-3,4-
dihydropyrimidin-1(2H)-yl)-N-(substituted)-
benzenesulfonamide (17, 18)
Yield%: 55, m.p.: 80–82°C, IR, cm-1: 3271, 3270, 3166
(NH, NH2), 3026 (CH arom.), 2965, 2834 (CH aliph.),
1310, 1145 (SO2). MS (m/z, RI%): 462 (M?, 1.6%), 310
(78%), 230 (89%), 129(100%). Anal. Calcd. For
C22H22N8O2S: C, 57.13; H, 4.79; N, 24.23. Found: C,
57.48; H, 4.54; N, 24.68.
A mixture of 4 or 6 (0.01.mol), phenyl isothiocyanate
(0.01 mol) and sodium hydroxide (0.01 mol) in ethanol
(20 ml) was refluxed for 3 h. The reaction mixture was
cooled, poured onto ice water, acidified with dil. HCl, then
the solid product was filtered and crystallized from dioxane
to give 17 or 18, respectively.
4-((3-Amino-5-oxo-1-phenyl-1H-pyrazol-4-
ylidene)methylamino)-N-(4,6-dimethyl-pyrimidin-2-
yl)benzenesulfonamide (13)
4-(5-Cyano-4-oxo-3-phenyl-2-thioxo-3,4-
dihydropyrimidin-1(2H)-yl)-N-(pyridine-2-yl)-
benzenesulfonamide (17)
Yield%: 60, m.p.: 77–79°C, IR, cm-1: 3245, 3244, 3121
(NH, NH2), 3034 (CH arom.), 2945, 2834 (CH aliph.),
1680 (C=O), 1332, 1156 (SO2). MS (m/z, RI%): 463 (M?,
6.6%), 345 (67%), 245 (89%), 125(100%). Anal. Calcd.
For C22H21N7O3S: C, 57.01; H, 4.57; N, 21.15. Found: C,
57.42; H, 4.83; N, 21.47.
Yield%: 70, m.p.: 110–112°C, IR, cm-1: 3364 (NH), 3032
(CH arom.), 2220 (CN), 1730 (C=O), 1312, 1146 (SO2),
1270 (C=S). MS (m/z, RI%): 461(M?, 25.5%), 226(100%),
184(53.6%), 134(31.9%), 65(29.6%). Anal. Calcd. For
C22H15N5O3S2: C, 57.25; H, 3.28; N, 15.17. Found: C,
57.66; H, 3.30; N, 15.45.
4-((3-Amino-5-imino-1H-pyrazol-4-ylidene)methylamino)-
N-(quinoxalin-2-yl)benzene-sulfonamide (14)
4-(5-Cyano-4-oxo-3-phenyl-2-thioxo-3,4-
dihydropyrimidin-1(2H)-yl)-N-(4,6-dimethyl-pyrimidin-2-
yl)benzenesulfonamide (18)
Yield%: 50, m.p.: 104-105o, IR, cm-1: 3422, 3390, 3224
(NH, NH2), 3026 (CH arom.), 2923, 2838 (CH aliph.),
1311, 1158 (SO2). MS (m/z, RI%): 408(M?, 0.5%), 224
(66%), 92(100%), 77 (88%), 65 (85%). Anal. Calcd. For
C18H16N8O2S: C, 52.93; H, 3.95; N, 27.43. Found: C,
53.12; H, 4.04; N, 27.89.
Yield%: 50, m.p.: 100–102°C, IR, cm-1: 3320 (NH), 3030
(CH arom.), 2218 (CN), 1690 (C=O), 1314, 1148 (SO2),
1270 (C=S). MS (m/z, RI%): 490 (M?, 5%), 310 (100%),
277 (31.7%), 152 (29.5%), 90 (29.3%). Anal. Calcd. For
C23H18N6O3S2: C, 56.31; H, 3.70; N, 17.13. Found: C,
56.76; H, 3.88; N, 17.34.
4-((3-Amino-5-imino-1-phenyl-1H-pyrazol-4-
ylidene)methylamino)-N-(quinoxalin-2-yl)-
benzenesulfonamide (15)
4-(4-amino-6-oxo-2-thioxo-1,6-dihydro-2H-pyrimidin-5-
ylidene-methylamino)-N-(quinoxalin-2-
yl)benzenesulfonamide (19)
Yield%: 55, m.p.: 90–92°C, IR, cm-1: 3277, 3234, 3145
(NH, NH2), 3055 (CH arom.), 2978, 2834 (CH aliph.),
1321, 1145 (SO2). MS (m/z, RI%): 484(M?, 1.08),
458(3.92%), 378(40.02%), 314(100%)., Anal. Calcd. for
C24H20N8O2S: C, 59.49; H, 4.16; N, 23.13. Found: C,
59.86; H, 4.49; N, 23.32.
A mixture of 9 (0.01 mol) and thiourea (0.01 mol) was
refluxed for 5 h in ethanol containing sodium ethoxide
(0.01 mol). The reaction mixture was cooled, poured onto
ice water, acidified with dil.HCl, then the precipitated solid
product was filtered and crystallized from methanol to give
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Med Chem Res (2012) 21:1376–1383
19. Yield%: 70, m.p.: 200–202°C, IR, cm-1: 3483, 3359,
3252 (NH, NH2), 3073 (CH arom.), 2959, 2837 (CH
aliph.), 1350, 1150 (SO2), 1233 (C=S). MS (m/z, RI%):
453 (M?, 3.2%), 359 (28.87%), 236 (100%), 145 (33.68%),
92 (33.39%). Anal. Calcd. For C19H15N7O3S2: C, 50.32; H,
3.33; N, 21.62. Found: C, 50.66; H, 3.77; N, 21.81.
Radiosensitizing activity
The same compounds used in the in vitro anticancer
screening; the pyrazole derivatives 11, 12, 14, 16 and the
pyrimidine derivative 18, were selected to be evaluated
again for their in vitro anticancer activity alone and in
combination with c-radiation. This study was conducted to
evaluate the ability of these compounds to enhance the cell
killing effect of c-radiation. Cells were subjected to a
single dose of c-radiation at a dose level of 4 Gy with a
dose rate of 1 Gy/min. Irradiation was performed in the
National Cancer Institute, Cairo University, using Gamma
cell-40 (60Co) source, the surviving fraction was measured
1 h. after subjection to radiation (Geng et al., 2005). The
surviving fractions were expressed as means standard
error. The results were analyzed using one-way ANOVA
test and the percentage of change in the surviving fraction
from control for each compound was calculated consider-
ing the control as 100% in the surviving fraction. The
results are given in Tables 2 and 3. The effect of radiation
on cytotoxic activity of different concentrations of com-
pound 11 on HEPG2 cell line is presented in Fig. 1.
In vitro anticancer screening
The human tumor cell lines (HEPG2 and MCF7) were
available at the National Cancer Institute, Cairo, Egypt.
Irradiation was performed in the National Cancer Institute,
Cairo, Egypt using Gamma cell-40 (60CO) source. The
antitumor activity of the newly synthesized compounds
was mesured using the sulfo-rhodamine-B stain (SRB)
assay by the method of (Skehan and Storeng 1990).
Cells were plated in 96-multiwell plate (104 cells/well)
for 24 h before treatment with the compounds to allow
attachment of cell to the wall of the plate. Tested com-
pounds 11, 12, 14, 16, and 18 were dissolved in DMSO and
diluted with saline to the appropriate volume. Different
concentrations of the compounds under test (5, 12.5, 25,
and 40 lM) were added to the cell monolayer. Triplicate
wells were prepared for each individual dose. Monolayer
cells were incubated with the compounds for 48 h at 37°C
and in atmosphere of 5% CO2. After 48 h, cells were fixed,
washed and stained for 30 min. with 0.4% (wt/vol) with
SRB dissolved in 1% acetic acid. Unbounded dye was
removed by four washes with 1% acetic acid, and attached
stain was recovered with Tris–EDTA buffer. Color inten-
sity was measured in an ELISA reader. The relation
between surviving fraction and drug concentration was
plotted to get the survival curve of each tumor cell line
after the specified time. The concentration required for
50% inhibition of cell viability (IC50) was calculated and
compared with the reference drug doxorubicin and the
results are given in Table 1.
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