Anticancer and radio-sensitizing evaluation of some new sulfonamide derivatives bearing pyridone, thiophene, and hydrazone moieties

Article abstract of DOI:10.1007/s11164-017-2903-x

Abstract: A series of new pyridone 5, 6, 8a–j, hydrazone 7a–j, and thiophene 9–12 derivatives bearing a sulfonamide moiety were synthesized from the starting material 4-chloro-N-(4-(1-(2-(2-cyanoacetyl)hydrazono)ethyl)phenyl) benzenesulfonamide 4. The target compounds were in vitro evaluated for their cytotoxic activity against a human liver cancer cell line (HepG2). Compounds 4 and 8d–j showed higher cytotoxic activity compared to doxorubicin, as a positive control. The radio-sensitizing ability of the promising compounds 4, 8d, and 8h was studied which showed an enhanced cytotoxic activity after combination with γ-radiation. Molecular modeling was performed in CA II/IX mimic active site to predict the binding possibility of the target compounds. All the synthesized compounds showed appropriate fitting with the amino acids in the binding pocket on the basis of their S score data and binding interactions. This binding possibility might contribute at least in part, to their anticancer activity. Graphical Abstract: A novel series of sulfonamide derivatives bearing a biologically active pyridone, thiophene, and hydrazone moieties was synthesized and screened for their cytotoxic activity against HepG2 cell line. The most potent compounds in this study 4, 8d, and 8h were evaluated for their radio-sensitizing activity.

Full text of DOI:10.1007/s11164-017-2903-x

Res Chem Intermed
DOI 10.1007/s11164-017-2903-x
Anticancer and radio-sensitizing evaluation of some
new sulfonamide derivatives bearing pyridone,
thiophene, and hydrazone moieties
Mostafa M. Ghorab1,2 Fatma A. Ragab3
•
•
Helmy I. Heiba1 Aiten M. Soliman1
•
Received: 20 December 2016 / Accepted: 7 February 2017
Ó Springer Science+Business Media Dordrecht 2017
Abstract A series of new pyridone 5, 6, 8a–j, hydrazone 7a–j, and thiophene 9–12
derivatives bearing a sulfonamide moiety were synthesized from the starting material
4-chloro-N-(4-(1-(2-(2-cyanoacetyl)hydrazono)ethyl)phenyl) benzenesulfonamide 4.
The target compounds were in vitro evaluated for their cytotoxic activity against a
human liver cancer cell line (HepG2). Compounds 4 and 8d–j showed higher
cytotoxic activity compared to doxorubicin, as a positive control. The radio-sensi-
tizing ability of the promising compounds 4, 8d, and 8h was studied which showed
an enhanced cytotoxic activity after combination with c-radiation. Molecular mod-
eling was performed in CA II/IX mimic active site to predict the binding possibility
of the target compounds. All the synthesized compounds showed appropriate fitting
with the amino acids in the binding pocket on the basis of their S score data and
binding interactions. This binding possibility might contribute at least in part, to their
anticancer activity.
Electronic supplementary material The online version of this article (doi:10.1007/s11164-017-2903-x)
contains supplementary material, which is available to authorized users.
&
Mostafa M. Ghorab
mmsghorab@yahoo.com
1
2
3
Department of Drug Radiation Research, National Center for Radiation Research and
Technology, Egyptian Atomic Energy Authority, Cairo, Egypt
Department of Pharmacognosy, College of Pharmacy, King Saud University,
P.O. Box 2457, Riyadh 11451, Saudi Arabia
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Cairo University, Cairo, Egypt
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M. M. Ghorab et al.
Graphical Abstract
A novel series of sulfonamide derivatives bearing a biologically active pyridone, thio-
phene, and hydrazone moieties was synthesized and screened for their cytotoxic activity
against HepG2 cell line. The most potent compounds in this study 4, 8d, and 8h were
evaluated for their radio-sensitizing activity.
Keywords Sulfonamide Á Pyridone Á Thiophene Á Hydrazone Á Anticancer Á
Radiosensitizers
Introduction
Radiotherapy is the second most successful treatment for cancer next to surgery [1].
Radiation delivers energy to tissues, causing ionization and excitation of atoms. The
effect of radiation is exerted through the generation of single and double strand
breaks, apoptosis of cells as they progress through the cell cycle and through the
generation of short-lived free radicals (ROS), which damage proteins and
membranes [2]. It is now well known that in the presence of chemotherapy, an
increased response occurs within the irradiated tissue.
Pyridones constitute an important class of anticancer agents [3] as they act
through many mechanisms including inhibition of tyrosine kinases such as FGFR
and VEGFR, Met and TAM family kinases [4, 5]. They were also identified as
inhibitors of the serine/threonine kinase PIM-1, which plays an important role in
cell cycle progression, signal transduction pathways, and apoptosis [6, 7].
Phosphodiesterase inhibitors act through PDE3, PDE4, and PDE5 inhibition [8],
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Anticancer and radio-sensitizing evaluation of some new…
Fig. 1 Anticancer agents containing pyridone, thiophene, and hydrazone moieties
e.g. cilostamide (Fig. 1), a selective PDE3 inhibitor, that shows synergism with the
anti-apoptotic action of PDE4 inhibitors in leukemia cells [9]. Survivin inhibitor is a
member of the inhibitor of apoptosis family (IAP) [9]. Farnesyl transferase
inhibitors (FTIs) act by preventing the proper functioning of the Ras protein [10].
Thiophene derivatives also show interesting antitumor activity [11], e.g.
NSC652287, that act through the induction of protein cross-linking [12] and OSI-
930, a selective inhibitor of Kit and tyrosine kinases through the inactivation of
cytochrome P450 (Fig. 1) [13]. In addition, hydrazones form the backbone of many
anticancer agents that act by inhibiting the dihydrofolate reductase enzyme [14],
inducing apoptosis through the inhibition of tubulin polymerization [15], arresting
the cell cycle at the G2/M phase [16, 17] c-Met tyrosine kinase inhibition [18], and
cytotoxic activity through the chelation of Fe(III), e.g. pyridoxal isonicotinoyl
hydrazone (Fig. 1) [19].
The considerable anticancer activity of sulfonamides makes them candidates of
choice to be combined with other pharmacologically active moieties for achieving
better cytotoxic activity. Sulfonamides’ anticancer activity is exerted through many
mechanisms, the most prominent of which is the inhibition of carbonic anhydrase
isozymes [20, 21]. Sulfonamides possess a zinc binding group that coordinates with
the Zn(II) ion of the CA active site and establish additional interactions promoted by
the aryl substituent in the region nearby the catalytic site [22, 23], and this is
consistent with the ‘‘tail approach’’ [24]. This moiety known as tail extends the
inhibitor allowing it to make multiple interactions with the amino acids towards the
outside of the active site. The addition of these tails can also alter the properties of
the CA inhibitor [22].
Based on this, and as a continuation of our work [25–27], we planned to
synthesize a novel series of sulfonamides bearing a biologically active pyridone,
hydrazone, thiophene, and fused thiophene derivatives, as these moieties may act as
a tail to improve the binding in the active site of CA, and they also possess
anticancer activity [3–5, 11, 28–30], in order to be evaluated against human liver
cancer cell line (HepG2) alone and in combination with c-radiation.
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M. M. Ghorab et al.
Experimental
Chemistry
Melting points were uncorrected and measured using a Stuart melting point
apparatus (Stuart Scientific, Redhill, UK). The IR spectra were recorded on ABB
´
Bomem FT-IR spectrometer MB 104 (ABB Bomem Inc., Quebec, Canada) using
1
KBr pellets. H-NMR spectra were recorded using a Bruker 300 and 400 NMR
spectrometers (Bruker, Flawil, Switzerland) operating at 300 and 400 MHz,
respectively. 13C-NMR spectra were recorded using a Bruker 100 NMR spectrom-
eters operating at 100 MHz. Mass spectra were run on Shimadzu GCMS/QP 5050
mass spectrometer (Shimadzu, Tokyo, Japan). Microanalyses were measured with
an elemental analyses system GmbH VarioEL V300 element analyzer (Elemental
Analysensysteme GmbH, Chennai, India) and were found within the limit of 0.4%
of theoretical values for all the synthesized compounds. The compound’s purity was
checked by thin layer chromatography (TLC) with precoated aluminum sheets silica
gel Merck 60 F254 and was visualized by UV lamp (Merck, Darmstadt, Germany).
The developing solvent system was benzene/methanol (7:3) and the spots were
visualized in UV chamber. The spectroscopic data and elemental analyses were
consistent with the assigned structures. IR spectra were performed at the National
Center for Radiation Research and Technology, Atomic Energy Authority. While
1H-NMR and 13C-NMR spectra were performed at the Chemical Warfare
department, Ministry of Defense. Mass spectra were performed at the Microana-
lytical Laboratories of Al-Azhar University. Elemental analyses were performed at
the Microanalytical Laboratories of the Faculty of Science, Cairo University.
4-Chlorobenzene sulfonyl chloride and 4-aminoacetophenon were purchased from
Sigma-Aldrich (St. Louis, MO).
4-Chloro-N-(4-(1-((4,6-diamino-3-cyano-2-oxopyridin-1(2H)-yl)imino)ethyl)phenyl)
benzenesulfonamide (5)
A mixture of compound 4 (3.9 g, 0.01 mol) and malononitrile (0.66 g, 0.01 mol)
was refluxed in dioxane (15 mL) containing triethylamine 5 drops for 6 h. The
reaction mixture was poured into ice-water and filtered. The obtained solid was
crystallized from ethanol to give 5. Yield, 50.1%; m.p. 168–170 °C. IR (KBr,
cm-1): 3383, 3334, 3283 (NH, 2NH2), 3010 (CH arom.), 2926, 2872 (CH aliph.),
1
2191 (CN), 1682 (CO), 1606 (C=N), 1337, 1162 (SO2), 748 (C–Cl). H-NMR
(400 MHz, DMSO-d6) d: 2.16 (s, 3H, CH3), 4.16 (s, 1H, CH-pyridone), 7.08–7.83
(m, 8H, Ar–H), 7.60 (s, 1H, SO2NH), 10.60, 10.94 (2 s, 4H, 2 NH2). 13C-NMR
(100 MHz, DMSO-d6) d: 22.5 (CH3), 66.8 (C–CN), 88.5 (CH-pyridone), 116.7
(CN), 119.8 (2), 127.7, 127.9 (2), 129.0 (2), 129.9 (2), 130.1, 130.5, 133.9 (C-
phenyl), 138.3 (N–C–NH2), 148.8 (CO), 157.5 (C=N), 166.2 (C–NH2). MS m/z (%):
457 (M?) (19.4), 459.5 (8.4), 438.7 (100). Anal. Calcd. For C20H17ClN6O3S
(456.91): C, 52.57; H, 3.75; N, 18.39; Found: C, 52.88; H, 3.96; N, 18.59.
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Anticancer and radio-sensitizing evaluation of some new…
N-(4-(1-((4-Amino-3-cyano-6-hydroxy-2-oxopyridin-1(2H)-yl)imino)ethyl)phenyl)-
4-chlorobenzenesulfonamide (6)
A mixture of compound 4 (3.9 g, 0.01 mol) and ethyl cyanoacetate (1.13 g,
0.01 mol) was refluxed in dioxane (15 mL) containing triethylamine 5 drops for 6 h.
The reaction mixture was poured into ice-water and filtered. The solid obtained was
crystallized from ethanol to give 6. Yield, 70.6%; m.p. 118–120 °C. IR (KBr,
cm-1): 3420 (OH), 3384, 3237, 3210 (NH, NH2), 3100 (CH arom.), 2927, 2853 (CH
1
aliph.), 2261 (CN), 1713 (CO), 1602 (C=N), 1330, 1184 (SO2), 743 (C–Cl). H-
NMR (300 MHz, DMSO-d6) d: 2.19 (s, 3H, CH3), 4.18 (s, 1H, CH-pyridone),
7.10–7.86 (m, 8H, Ar–H), 7.67 (s, 1H, SO2NH), 10.62 (s, 2H, NH2), 10.96 (s, 1H,
OH). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 66.8 (C–CN), 75.5 (CH-
pyridone), 116.7 (CN), 119.8 (2), 127.7, 127.9 (2), 129.0 (2), 129.9 (2), 130.1,
130.3, 133.9 (C-phenyl), 148.8 (CO), 157.5 (C=N), 165.3 (C–OH), 166.2 (C–NH2).
MS m/z (%): 458 (M?) (2.6), 460 (0.9), 60.8 (100). Anal. Calcd. For C20H16ClN5-
O4S (457.89): C, 52.45; H, 3.52; N, 15.29; Found: C, 52.71; H, 3.82; N, 15.46.
General procedure for the synthesis of compounds 7a–j
A mixture of 4 (3.9 g, 0.01 mol) and aromatic aldehydes (0.01 mol) namely,
furfural, benzaldehyde, 4-methyl benzaldehyde, cinnamaldehyde, 2-methoxyben-
zaldehyde, 4-methoxybenzaldehyde, 2-chlorobenzaldehyde, 4-chlorobenzaldehyde,
4-dimethyl amino benzaldehyde, piperonal, in ethanol (15 mL) containing
piperidine (0.5 mL) was refluxed for 3 h. The reaction mixture was poured into
ice-water containing few drops of dil. HCl and the obtained solid was crystallized
from dioxane to give 7a–j, respectively.
Chloro-N-(4-(1-(2-(2-cyano-3-(furan-2-yl)acryloyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7a)
Yield, 71.1%; m.p. 253–255 °C. IR (KBr, cm-1): 3368, 3300 (2NH), 3033 (CH
arom.), 2934, 2865 (CH aliph.), 2203 (CN), 1700 (CO), 1610 (C=N), 1341, 1162
(SO2), 771 (C–Cl). 1H-NMR (300 MHz, DMSO-d6) d: 2.25 (s, 3H, CH3), 6.84–8.01
(m, 11H, Ar–H), 7.43 (s, 1H, SO2NH), 8.14 (s, 1H, CH), 10.53 (s, 1H, NHCO). 13C-
NMR (100 MHz, DMSO-d6) d: 22.3 (CH3), 100.1, 113.8 (C-furan), 113.9 (C–CN),
116.2 (CN), 119.1 (2) (C-phenyl), 119.4, 121.9 (2), 127.5 (2), 127.7 (2), 128.6,
128.7 129.3 (C-phenyl), 129.5 (C-furan), 133.2 (C=N), 137.8 (C-furan), 138.3 (CH),
148.7 (CO). Anal. Calcd. For C22H17ClN4O4S (468.91): C, 56.35; H, 3.65; N, 11.95;
Found: C, 56.43; H, 3.70; N, 12.13.
4-Chloro-N-(4-(1-(2-(2-cyano-3-phenylacryloyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7b)
Yield, 90.2%; m.p. 242–244 °C. IR (KBr, cm-1): 3369, 3348 (2NH), 3040 (CH
arom.), 2929, 2864 (CH aliph.), 2203 (CN), 1688 (CO), 1595 (C=N), 1353, 1163
(SO2), 753 (C–Cl). 1H-NMR (300 MHz, DMSO-d6) d: 2.17 (s, 3H, CH3), 7.17–7.99
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M. M. Ghorab et al.
(m, 13H, Ar–H), 7.43 (s, 1H, SO2NH), 7.98 (s, 1H, CH), 10.11 (s, 1H, NHCO). 13C-
NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 100.2 (C–CN), 113.7 (CN), 113.9 (2),
116.1, 119.0, 119.4 (2), 121.9 (2), 127.4 (2), 127.5 (2), 127.7 (2), 128.6, 129.3,
129.7, 133.2 (C-phenyl), 137.8 (C=N), 138.3 (CH), 148.7 (CO). MS m/z (%): 479
(M?) (9.4), 481 (4.4), 194 (100). Anal. Calcd. For C24H19ClN4O3S (478.95): C,
60.19; H, 4.00; N, 11.70; Found: C, 60.33; H, 4.29; N, 12.10.
4-Chloro-N-(4-(1-(2-(2-cyano-3-(p-tolyl)acryloyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7c)
Yield, 73.2%; m.p. 144–146 °C. IR (KBr, cm-1): 3375, 3215 (2NH), 3067 (CH
arom.), 2940, 2853 (CH aliph.), 2208 (CN), 1675 (CO), 1615 (C=N), 1342, 1158
1
(SO2), 752 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.26 (s, 3H, CH3), 2.41 (s,
3H, CH3 tolyl), 7.18–8.09 (m, 12H, Ar–H), 7.47 (s, 1H, SO2NH), 8.05 (s, 1H, CH),
9.95 (s, 1H, NHCO). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 26.6 (CH3),
100.3 (C–CN), 113.7 (CN), 113.9 (2), 116.1, 119.4 (2), 121.9 (2), 127.4 (2), 127.5,
127.7 (2), 127.9 (2), 128.6, 129.4, 129.6, 133.2 (C-phenyl), 137.8 (C=N), 138.3
(CH), 148.7 (CO). Anal. Calcd. For C25H21ClN4O3S (492.98): C, 60.91; H, 4.29; N,
11.36 Found: C, 61.21; H, 4.43; N, 11.71.
4-Chloro-N-(4-(1-(2-(2-cyano-5-phenylpenta-2,4-dienoyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7d)
Yield, 95.1%; m.p. 190–192 °C. IR (KBr, cm-1): 3377, 3339 (2NH), 3021 (CH
arom.), 2934, 2860 (CH aliph.), 2210 (CN), 1671 (CO), 1618 (C=N), 1347, 1160
(SO2), 745 (C–Cl). 1H-NMR (400 MHz, DMSO-d6) d: 2.17 (s, 3H, CH3), 7.19–7.85
(m, 13H, Ar–H), 7.40 (s, 1H, SO2NH), 8.04, 8.07 (2d, 2H, CH=CH, J = 8.0 Hz),
8.66 (s, 1H, CH), 10.53 (s, 1H, NHCO). 13C-NMR (100 MHz, DMSO-d6) d: 22.4
(CH3), 100.2 (C–CN), 113.7 (CN), 113.9 (2) (C-phenyl), 114.3 (CH=CH), 116.1,
117.3, 119.1 (2), 121.9 (2), 127.4 (2), 127.5, 127.7 (C-phenyl), 128.3 (CH–CH),
128.6, 129.3, 129.6, 133.2 (C-phenyl), 134.0 (CH–C6H5), 137.8 (C=N), 138.3 (CH),
148.7 (CO). Anal. Calcd. For C26H21ClN4O3S (504.99): C, 61.84; H, 4.19; N, 11.09;
Found: C, 62.14; H, 4.33; N, 11.32.
4-Chloro-N-(4-(1-(2-(2-cyano-3-(2-methoxyphenyl)acryloyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7e)
Yield, 60.9%; m.p. 128–130 °C. IR (KBr, cm-1): 3379, 3329 (2NH), 3073 (CH
arom.), 2938, 2842 (CH aliph.), 2243 (CN), 1655(CO), 1608 (C=N), 1303, 1188
1
(SO2), 747 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.17 (s, 3H, CH3), 3.91 (s,
3H, OCH3). 6.99–7.99 (m, 12H, Ar–H), 7.43 (s, 1H, SO2NH), 8.03 (s, 1H, CH),
10.36 (s, 1H, NHCO). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 71.6
(OCH3), 100.2 (C–CN), 105.2 (C-phenyl), 113.7 (CN), 113.9 (2), 114.3, 115.1,
116.1, 119.4, 120.2, 121.9 (2), 127.7 (2), 127.9 (2), 130.2, 130.5, 134.0 (C-phenyl),
138.3 (CH), 140.8 (C=N), 145.3 (C-phenyl), 148.7 (CO). Anal. Calcd. For
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Anticancer and radio-sensitizing evaluation of some new…
C25H21ClN4O4S (508.98): C, 58.99; H, 4.16; N, 11.01; Found: C, 59.22; H, 4.32; N,
11.17.
4-Chloro-N-(4-(1-(2-(2-cyano-3-(4-methoxyphenyl)acryloyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7f)
Yield, 67.8%; m.p. 126–128 °C. IR (KBr, cm-1): 3392, 3319 (2NH), 3076 (CH
arom.), 2935, 2834 (CH aliph.), 2180 (CN), 1661 (CO), 1620 (C=N), 1350, 1169
1
(SO2), 743 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.17 (s, 3H, CH3), 3.81 (s,
3H, OCH3). 6.94–8.08 (m, 12H, Ar–H), 7.47 (s, 1H, SO2NH), 8.62 (s, 1H, CH), 9.87
(s, 1H, NHCO). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 69.5 (OCH3),
100.2 (C–CN), 105.2 (2) (C-phenyl), 115.3 (CN), 119.7 (2), 127.7, 127.9, 129.0 (4),
130.0 (2), 130.1 (2), 132.2, 137.4 (2) (C-phenyl), 137.8 (C=N), 138.6 (CH), 140.2
(C-phenyl), 148.7 (CO). Anal. Calcd. For C25H21ClN4O4S (508.98): C, 58.99; H,
4.16; N, 11.01; Found: C, 59.15; H, 4.38; N, 11.13.
4-Chloro-N-(4-(1-(2-(3-(2-chlorophenyl)-2-cyanoacryloyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7g)
Yield, 72.1%; m.p. 126–128 °C. IR (KBr, cm-1): 3365, 3323 (2NH), 3021 (CH
arom.), 2931, 2856 (CH aliph.), 2213 (CN), 1679 (CO), 1587 (C=N), 1342, 1167
(SO2), 756 (C–Cl). 1H-NMR (400 MHz, DMSO-d6) d: 2.17 (s, 3H, CH3), 7.00–8.15
(m, 12H, Ar–H), 7.45 (s, 1H, SO2NH), 8.17 (s, 1H, CH), 10.33 (s, 1H, NHCO). 13C-
NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 100.2 (C–CN), 113.7 (CN), 113.9 (2),
115.3, 118.1, 118.4, 119.2 (2), 125.0 (2), 127.8, 127.9, 128.0 (2), 128.4, 128.5,
129.5, 129.8, 132.0 (C-phenyl), 137.8 (C=N), 138.2 (CH), 142.2 (CO). Anal. Calcd.
For C24H18Cl2N4O3S (513.40): C, 56.15; H, 3.53; N, 10.91; Found: C, 56.31; H,
3.49; N, 10.85.
4-Chloro-N-(4-(1-(2-(3-(4-chlorophenyl)-2-cyanoacryloyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7h)
Yield, 66.2%; m.p. 103–105 °C. IR (KBr, cm-1): 3357, 3341 (2NH), 3059 (CH arom.),
2942, 2851 (CH aliph.), 2214 (CN), 1678 (CO), 1605 (C=N), 1341, 1156 (SO2), 762 (C–
Cl). 1H-NMR (400 MHz, DMSO-d6) d: 2.17 (s, 3H, CH3), 7.12–8.10 (m, 12H, Ar–H),
7.47 (s, 1H, SO2NH), 8.43 (s, 1H, CH), 10.68 (s, 1H, NHCO). 13C-NMR (100 MHz,
DMSO-d6) d: 22.4 (CH3), 100.2 (C–CN), 113.7 (CN), 113.9 (2), 116.2, 118.4 (2), 119.2
(2), 125.0 (2), 127.9 (2), 128.0, 128.2 (2), 128.5, 129.5, 129.8, 132.1 (C-phenyl), 137.8
(C=N), 138.2 (CH), 142.2 (CO). Anal. Calcd. For C24H18Cl2N4O3S (513.40): C, 56.15; H,
3.53; N, 10.91; Found: C, 56.02; H, 3.34; N, 10.75.
4-Chloro-N-(4-(1-(2-(2-cyano-3-(4-(dimethylamino)phenyl)acryloyl)hydrazono)ethyl)phenyl)
benzenesulfonamide (7i)
Yield, 36.8%; m.p. 228–230 °C. IR (KBr, cm-1): 3355, 3308 (2NH), 3095 (CH
arom.), 2918, 2879 (CH aliph.), 2202 (CN), 1671 (CO), 1611 (C=N), 1338, 1160
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M. M. Ghorab et al.
1
(SO2), 757 (C–Cl). H-NMR (300 MHz, DMSO-d6) d: 2.24 (s, 3H, CH3), 3.07 (s,
6H, 2CH3), 6.82–7.94 (m, 12H, Ar–H), 7.76 (s, 1H, SO2NH), 8.01 (s, 1H, CH),
10.55 (s, 1H, NHCO). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 50.3 (2)
(N(CH3)2), 100.2 (C–CN), 102.3 (2) (C-phenyl), 113.7 (CN), 113.9 (2), 114.2,
116.1, 121.9 (2), 127.7 (2), 127.9 (2), 128.1 (2), 128.6, 129.6, 133.2 (C-phenyl),
137.8 (C=N), 138.0 (C-phenyl), 138.3 (CH), 148.7 (CO). Anal. Calcd. For
C26H24ClN5O3S (522.02): C, 59.82; H, 4.63; N, 13.42; Found: C, 60.13; H, 4.89; N,
13.60.
N-(4-(1-(2-(3-(Benzo[d][1,3]dioxol-5-yl)-2-cyanoacryloyl)hydrazono)ethyl)phenyl)-
4-chlorobenzenesulfonamide (7j)
Yield, 50.3%; m.p. 251–253 °C. IR (KBr, cm-1): 3387, 3370 (2NH), 3092 (CH
arom.), 2915, 2867 (CH aliph.), 2216 (CN), 1667 (CO), 1598 (C=N), 1348, 1179
1
(SO2), 753 (C–Cl). H-NMR (300 MHz, DMSO-d6) d: 2.25 (s, 3H, CH3), 6.17 (s,
2H, CH2), 7.11–7.79 (m, 11H, Ar–H), 7.55 (s, 1H, SO2NH), 8.09 (s, 1H, CH), 10.57
(s, 1H, NHCO). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 99.8 (CH2), 100.2
(C–CN), 103.3, 105.6 (C-phenyl), 113.7 (CN), 113.9 (2), 114.2, 116.2, 117.5, 119.4
(2), 121.9 (2), 127.7 (2), 130.2, 130.5, 134.0 (C-phenyl), 137.8 (C=N), 137.9, 138.0
(C-phenyl), 138.3 (CH), 148.7 (CO). Anal. Calcd. For C25H19ClN4O5S (522.96): C,
57.42; H, 3.66; N, 10.71; Found: C, 57.22; H, 3.38; N, 10.43.
General procedure for the synthesis of compounds 8a–j
Method (A): A mixture of 4 (3.9 g, 0.01 mol) and arylidene malononitrile
(0.01 mol) in ethanol (15 mL) containing piperidine (0.5 mL) was refluxed for
4 h. The reaction mixture was poured into ice-water containing few drops of dil.
HCl and filtered. The solid obtained was crystallized from dioxane to give 8a–j,
respectively.
Method (B): A mixture of compounds 7a–j (0.01 mol) and malononitrile (0.66 g,
0.01 mol) in dioxane (15 mL) containing piperidine (0.5 mL) was refluxed for 5 h.
The reaction mixture was cooled and poured into ice-water containing few drops of
dil. HCl and filtered. The obtained solid was crystallized from dioxane to give 8a–j.
N-(4-(1-((6-Amino-3,5-dicyano-4-(furan-2-yl)-2-oxopyridin-1(2H)-
yl)imino)ethyl)phenyl)-4-chlorobenzenesulfonamide (8a)
Yield, 35.2%; m.p. 133–135 °C. IR (KBr, cm-1): 3330, 3245, 3200 (NH2, NH),
3060 (CH arom.), 2918, 2847 (CH aliph.), 2211, 2200 (2 CN), 1676 (CO), 1601
1
(C=N), 1341, 1170 (SO2), 761 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.16 (s,
3H, CH3), 7.01–7.75 (m, 11H, Ar–H), 7.56 (s, 1H, SO2NH), 10.73 (s, 2H, NH2).
13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 76.5 (C–CN), 109.4, 112.8 (C-
furan), 115.8 (2) (CN), 116.4 (2) (C-phenyl), 121.5 (C–CN), 127.5, 128.7 (2), 129.1
(2), 130.0 (2), 137.5, 138.0, 140.0 (C-phenyl), 140.0 (C–NH2), 143.7, 149.8 (C-
furan), 150.0 (CO), 159.5 (C=N), 169.4 (C-pyridone). Anal. Calcd. For C25H17-
ClN6O4S (532.96): C, 56.34; H, 3.22; N, 15.77; Found: C, 56.45; H, 3.39; N, 15.89.
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N-(4-(1-((6-Amino-3,5-dicyano-2-oxo-4-phenylpyridin-1(2H)-
yl)imino)ethyl)phenyl)-4-chlorobenzenesulfonamide (8b)
Yield, 67.8%; m.p. 126–128 °C. IR (KBr, cm-1): 3334, 3238, 3204 (NH2, NH),
3048 (CH arom.), 2920, 2851 (CH aliph.), 2215, 2198 (2 CN), 1670 (CO), 1602
1
(C=N), 1349, 1161 (SO2), 755 (C–Cl). H-NMR (300 MHz, DMSO-d6) d: 2.14 (s,
3H, CH3), 7.14–8.05 (m, 13H, Ar–H), 7.54 (s, 1H, SO2NH), 10.61 (s, 2H, NH2).
13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 76.5, 115.3 (C–CN), 115.8 (2)
(CN), 116.4 (2), 127.5, 127.9, 128.1 (2), 128.7 (2), 128.9 (2), 129.1 (2), 130.0 (2),
132.5, 137.5, 138.1, 140.0 (C-phenyl), 140.0 (C–NH2), 160.0 (CO), 163.4 (C=N),
169.0 (C-pyridone). Anal. Calcd. For C27H19ClN6O3S (543): C, 59.72; H, 3.53; N,
15.48; Found: C, 59.99; H, 3.64; N, 15.54.
N-(4-(1-((6-Amino-3,5-dicyano-2-oxo-4-(p-tolyl)pyridin-1(2H)-yl)imino)ethyl)phenyl)-
4-chlorobenzenesulfonamide (8c)
Yield, 78.7%; m.p. 132–134 °C. IR (KBr, cm-1): 3328, 3247, 3213 (NH2, NH),
3040 (CH arom.), 2940, 2922 (CH aliph.), 2212, 2195 (2 CN), 1667 (CO), 1606
1
(C=N), 1344, 1162 (SO2), 756 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.27 (s,
3H, CH3 tolyl), 2.38 (s, 3H, CH3), 7.15–8.04 (m, 12H, Ar–H), 7.41 (s, 1H, SO2NH),
10.61 (s, 2H, NH2). 13C-NMR (100 MHz, DMSO-d6) d: 22.5 (CH3), 29.1 (CH3
tolyl), 83.6, 120.8 (C–CN), 128.2 (2) (CN), 128.7 (2), 127.5, 129.2 (2), 129.5 (2),
130.0 (3), 130.1 (5), 131.8 (2), 134.6 (C-phenyl), 138.5 (C–NH2), 147.8 (CO), 157.1
(C=N), 163.7 (C-pyridone). Anal. Calcd. For C28H21ClN6O3S (557.02): C, 60.37; H,
3.80; N, 15.09; Found: C, 60.55; H, 4.12; N, 15.17.
N-(4-(1-((6-Amino-3,5-dicyano-2-oxo-4-(styryl)pyridin-1(2H)-yl)imino)ethyl)phenyl)-
4-chlorobenzenesulfonamide (8d)
Yield, 27.3%; m.p. 176–178 °C. IR (KBr, cm-1): 3353, 3247, 3213 (NH2, NH), 3060
(CH arom.), 2934, 2856 (CH aliph.), 2203, 2186 (2 CN), 1687 (CO), 1600 (C=N),
1345, 1161 (SO2), 757 (C–Cl). 1H-NMR (400 MHz, DMSO-d6) d: 2.21 (s, 3H, CH3),
7.33–8.01 (m, 13H, Ar–H), 7.61 (d, 1H, CH=CH, J = 8.4 Hz), 7.63 (d, 1H, CH–C6H5,
J = 8.4 Hz), 7.57 (s, 1H, SO2NH), 10.61 (s, 2H, NH2). 13C-NMR (100 MHz, DMSO-
d6) d: 22.2 (CH3), 76.1, 110.3 (C–CN), 115.8 (2) (CN), 116.4 (2) (C-phenyl), 125.9 (C-
styryl) 127.5, 127.9, 128.5 (2), 128.7 (2), 128.9 (2), 129.1 (2), 130.0 (2) (C-phenyl),
131.1 (C-styryl), 135.4, 137.5, 137.7, 140.0 (C-phenyl), 140.0 (C–NH2), 160.5 (CO),
163.4 (C=N), 170.5 (C-pyridone). Anal. Calcd. For C29H21ClN6O3S (569.03): C, 61.21;
H, 3.72; N, 14.77; Found: C, 61.46; H, 3.83; N, 14.95.
N-(4-(1-((6-Amino-3,5-dicyano-4-(2-methoxyphenyl)-2-oxopyridin-1(2H)-
yl)imino)ethyl)phenyl)-4-chlorobenzenesulfonamide (8e)
Yield, 48.1%; m.p. 143–145 °C. IR (KBr, cm-1): 3320, 3227, 3217 (NH2, NH),
3043 (CH arom.), 2920, 2846 (CH aliph.), 2215, 2190 (2 CN), 1664 (CO), 1601
1
(C=N), 1338, 1168 (SO2), 743 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.17 (s,
123

M. M. Ghorab et al.
3H, CH3), 3.84 (s, 3H, OCH3), 6.93–8.16 (m, 12H, Ar–H), 7.48 (s, 1H, SO2NH),
10.59 (s, 2H, NH2). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 40.3 (OCH3),
66.4 (C–CN), 111.4 (C-phenyl), 115.3 (C–CN), 115.8 (2) (CN), 116.4 (2), 119.8,
120.9, 127.5, 128.7 (2), 128.9, 129.1 (2), 129.7, 130.0 (2), 137.5, 137.8, 140.0 (C-
phenyl), 140.0 (C–NH2), 157.5 (C-phenyl), 160.0 (CO), 163.5 (C=N), 169.1 (C-
pyridone). Anal. Calcd. For C28H21ClN6O4S (573.02): C, 58.69; H, 3.69; N, 14.67;
Found: C, 58.81; H, 3.91; N, 14.86.
N-(4-(1-((6-Amino-3,5-dicyano-4-(4-methoxyphenyl)-2-oxopyridin-1(2H)-
yl)imino)ethyl)phenyl)-4-chlorobenzenesulfonamide (8f)
Yield, 34.5%; m.p. 143–145 °C. IR (KBr, cm-1): 3328, 3297, 3181 (NH2, NH), 3037
(CH arom.), 2946, 2919 (CH aliph.), 2217, 2190 (2 CN), 1655 (CO), 1601 (C=N),
1336, 1162 (SO2), 756 (C–Cl). 1H-NMR (400 MHz, DMSO-d6) d: 2.17 (s, 3H, CH3),
3.8 (s, 3H, OCH3), 7.12–8.03 (m, 12H, Ar–H), 7.63 (s, 1H, SO2NH), 10.60 (s, 2H,
NH2). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 33.3 (OCH3), 66.2 (C–CN),
114.2 (2) (C-phenyl), 115.3 (C–CN), 115.8 (2) (CN), 116.4 (2), 124.8, 127.5, 128.7 (2),
129.1 (2), 129.7 (2), 130.0 (2), 130.2, 130.5, 134.0 (C-phenyl), 137.8 (C–NH2), 160.0
(CO), 163.4 (C=N), 169.4 (C-pyridone). Anal. Calcd. For C28H21ClN6O4S (573.02): C,
58.69; H, 3.69; N, 14.67; Found: C, 58.87; H, 3.84; N, 14.85.
N-(4-(1-((6-Amino-4-(2-chlorophenyl)-3,5-dicyano-2-oxopyridin-1(2H)-
yl)imino)ethyl)phenyl)-4-chlorobenzenesulfonamide (8g)
Yield, 39.1%; m.p. 128–130 °C. IR (KBr, cm-1): 3328, 3247, 3213 (NH2, NH),
3040 (CH arom.), 2965, 2930 (CH aliph.), 2217, 2195 (2 CN), 1668 (CO), 1601
1
(C=N), 1341, 1171 (SO2), 748 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.17 (s,
3H, CH3), 7.20–8.05 (m, 12H, Ar–H), 7.50 (s, 1H, SO2NH), 10.62 (s, 2H, NH2).
13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 66.6, 115.3 (C–CN), 115.8 (2)
(CN), 116.4 (2), 126.7, 127.5, 127.9, 128.7 (2), 129.1 (2), 129.3, 129.9, 130.0 (2),
135.3, 135.8, 137.5, 137.8, 140.0 (C-phenyl), 140.0 (C–NH2) 160.0 (CO), 163.1
(C=N), 169.4 (C-pyridone). Anal. Calcd. For C27H18Cl2N6O3S (577.44): C, 56.16;
H, 3.14; N, 14.55; Found: C, 56.35; H, 3.27; N, 14.79.
N-(4-(1-((6-Amino-4-(4-chlorophenyl)-3,5-dicyano-2-oxopyridin-1(2H)-
yl)imino)ethyl)phenyl)-4-chlorobenzenesulfonamide (8h)
Yield, 26.6%; m.p. 161–163 °C. IR (KBr, cm-1): 3322, 3247, 3214 (NH2, NH),
3068 (CH arom.), 2917, 2850 (CH aliph.), 2218, 2215 (2 CN), 1666 (CO), 1603
1
(C=N), 1356, 1172 (SO2), 767 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.15 (s,
3H, CH3), 7.08–8.03 (m, 12H, Ar–H), 7.47 (s, 1H, SO2NH), 10.62 (s, 2H, NH2).
13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 73.5, 115.3 (C–CN), 115.8 (2)
(CN), 116.4 (2), 127.5, 128.7 (2), 128.9 (2), 129.1 (2), 130.0 (2), 130.5 (2), 131.0,
133.5, 137.5, 137.8, 140.0 (C-phenyl), 140.0 (C–NH2), 160.0 (CO), 163.4 (C=N),
169.5 (C-pyridone). Anal. Calcd. For C27H18Cl2N6O3S (577.44): C, 56.16; H, 3.14;
N, 14.55; Found: C, 56.32; H, 3.23; N, 14.68.
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Anticancer and radio-sensitizing evaluation of some new…
N-(4-(1-((6-Amino-3,5-dicyano-4-(4-(dimethylamino)phenyl)-2-oxopyridin-1(2H)-
yl)imino)ethyl)phenyl)-4-chlorobenzenesulfonamide (8i)
Yield, 42.2%; m.p. 151–153 °C. IR (KBr, cm-1): 3387, 3247, 3213 (NH2, NH),
3036 (CH arom.), 2937, 2857 (CH aliph.), 2183, 2148 (2 CN), 1657 (CO), 1586
1
(C=N), 1366, 1170 (SO2), 760 (C–Cl). H-NMR (300 MHz, DMSO-d6) d: 2.22 (s,
3H, CH3), 3.06 (s, 6H, 2CH3), 6.80–7.99 (m, 12H, Ar–H), 7.75 (s, 1H, SO2NH),
10.62 (s, 2H, NH2). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 40.1 (2),
(N(CH3)2), 71.3 (C–CN), 111.7 (2) (C-phenyl), 115.3 (C–CN), 115.8 (2) (CN),
116.4 (2), 122.0, 127.5, 128.7 (2), 129.1 (2), 130.0 (2), 130.3 (2), 137.5, 137.8,
140.0 (C-phenyl), 140.0 (C–NH2), 150.3 (C-phenyl), 160.0 (CO), 164.3 (C=N),
169.1 (C-pyridone). Anal. Calcd. For C29H24ClN7O3S (586.06): C, 59.43; H, 4.13;
N, 16.73; Found: C, 59.59; H, 4.19; N, 16.84.
N-(4-(1-((6-Amino-4-(benzo[d][1,3]dioxol-5-yl)-3,5-dicyano-2-oxopyridin-1(2H)-
yl)imino)ethyl)phenyl)-4-chlorobenzenesulfonamide (8j)
Yield, 65.0%; m.p. 118–120 °C. IR (KBr, cm-1): 3387, 3300, 3266 (NH2, NH),
3060 (CH arom.), 2937, 2857 (CH aliph.), 2183, 2148 (2 CN), 1659 (CO), 1567
1
(C=N), 1356, 1152 (SO2), 751 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.17 (s,
3H, CH3), 6.07 (s, 2H, O–CH2–O), 6.96–8.04 (m, 11H, Ar–H), 7.70 (s, 1H,
SO2NH), 10.64 (s, 2H, NH2). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 72.5
(C–CN), 101.2 (CH2), 108.0, 112.8 (C-phenyl), 115.3 (C–CN), 115.8 (2) (CN),
118.1 (2), 118.3, 125.8, 127.5, 128.5 (2), 129.7 (2), 129.9 (2), 137.5, 138.1, 140.0
(C-phenyl), 140.0 (C–NH2), 148.0, 148.7 (C-phenyl), 160.0 (CO), 163.4 (C=N),
169.4 (C-pyridone). Anal. Calcd. For C28H19ClN6O5S (587.01): C, 57.29; H, 3.26;
N, 14.32; Found: C, 57.61; H, 3.43; N, 14.67.
4-Chloro-N-(4-(1-(2-(2,4-diamino-5-cyanothiophene-3-carbonyl)hydrazono)ethyl)
phenyl) benzenesulfonamide (9)
A mixture of compound 4 (3.9 g, 0.01 mol), malononitrile (0.66 g, 0.01 mol), and
elemental sulfur (0.32 g, 0.01 mol) were refluxed in ethanol (15 mL) containing
triethylamine 5 drops for 6 h. The reaction mixture was poured into ice-water and
filtered. The obtained solid was crystallized from dioxane to give 9. Yield, 52.2%;
m.p. [ 300 °C. IR (KBr, cm-1): 3392, 3324, 3198 (2NH, 2NH2), 3066 (CH arom.),
2931, 2865 (CH aliph.), 2208 (CN), 1695 (CO), 1598 (C=N), 1334, 1167 (SO2), 752
1
(C–Cl). H-NMR (400 MHz, DMSO-d6) d: 2.16 (s, 3H, CH3), 7.58–7.87 (m, 8H,
Ar–H), 7.68 (s, 1H, SO2NH), 7.79 (s, 2H, NH2), 10.56 (s, 1H, NH), 10.95 (s, 2H,
NH2). 13C-NMR (100 MHz, DMSO-d6) d: 22.4 (CH3), 66.6 (C–CN), 115.3 (C-
thiophene), 115.3 (CN), 119.7 (2), 127.7, 127.9 (2), 129.0 (2), 130.0 (2) (C-phenyl),
132.2 (C–NH2), 137.5, 137.8, 138.6 (C-phenyl), 148.7 (C=N), 154.8 (CO), 166.2
(S–C–NH2). Anal. Calcd. For C20H17ClN6O3S2 (488.97): C, 49.13; H, 3.50; N,
17.19; Found: C, 49.01; H, 3.42; N, 16.91.
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M. M. Ghorab et al.
Ethyl-3,5-diamino-4-(2-(1-(4-(4-chlorophenylsulfonamido)phenyl)
ethylidene)hydrazinecarbonyl) thiophene-2-carboxylate (10)
A mixture of compound 4 (3.9 g, 0.01 mol), ethyl cyanoacetate (1.13 g, 0.01 mol)
and elemental sulfur (0.32 g, 0.01 mol) were refluxed in ethanol (15 mL) containing
triethylamine 5 drops for 6 h. The reaction mixture was poured into ice-water and
filtered. The obtained solid was crystallized from dioxane to give 10. Yield, 50.6%;
m.p. [ 300 °C. IR (KBr, cm-1): 3389, 3298, 3200 (NH, 2NH2), 3080 (CH arom.),
2925, 2855 (CH aliph.), 1742, 1679 (2 CO), 1601 (C=N), 1367, 1174 (SO2), 748
(C–Cl). 1H-NMR (400 MHz, DMSO-d6) d: 1.03 (t, 3H, CH3CH2, J = 8.8 Hz), 2.16
(s, 3H, CH3), 4.17 (q, 2H, CH2CH3, J = 8.8 Hz), 7.08–8.03 (m, 8H, Ar–H), 7.68 (s,
1H, SO2NH), 7.79 (s, 2H, NH2), 10.54 (s, H, NH), 10.95 (s, 2H, NH2). 13C-NMR
(100 MHz, DMSO-d6) d: 20.1 (CH3CH2), 24.4 (CH3), 60.3 (CH2CH3), 119.7 (C-
thiophene), 119.7 (2) (C-phenyl), 126.0 (C–CO ester), 127.7, 127.9 (2), 129.0 (2),
129.9 (2) (C-phenyl), 132.2 (C–NH2), 137.5, 137.8, 138.6 (C-phenyl), 148.7 (C=N),
163.5 (CO ester), 166.2 (CO), 167.5 (S–C–NH2). Anal. Calcd. For C22H22ClN5O5S2
(536.02): C, 49.30; H, 4.14; N, 13.07; Found: C, 49.08; H, 3.82; N, 12.89.
N-(4-(1-(2-(2-Amino-5,6-dihydro-4H-cyclopenta[b]thiophene-3-
carbonyl)hydrazono)ethyl)phenyl)-4-chlorobenzenesulfonamide (11)
To a solution mixture of compound 4 (3.9 g, 0.01 mol), absolute ethanol (15 mL),
triethylamine 5 drops and cyclopentanone (0.84 g, 0.01 mol), elemental sulfur (0.32 g,
0.01 mol) were added. The reaction mixture was refluxed for 2 h, then poured into ice-
water and filtered. The solid obtained was crystallized from dioxane to give 11. Yield,
34.0%; m.p. 166–168 °C. IR (KBr, cm-1): 3382, 3315, 3257 (2NH, NH2), 3086 (CH
arom.), 2937, 2843 (CH aliph.), 1656 (CO), 1599 (C=N), 1370, 1183 (SO2), 752 (C–
Cl). 1H-NMR (400 MHz, DMSO-d6) d: 2.16 (s, 3H, CH3), 2.24 (m, 2H, CH2
cyclopentane), 3.04, 3.09 (2t, 4H, 2CH2 cyclopentane, J = 8.0 Hz), 7.13–7.77 (m, 8H,
Ar–H), 7.64 (s, 1H, SO2NH), 10.63 (s, 1H, NH), 10.97 (s, 2H, NH2). 13C-NMR
(100 MHz, DMSO-d6) d: 24.4 (CH3), 25.3, 26.9, 39.4 (CH2 cyclopentane), 119.7 (C–
CO), 119.7 (2) (C-phenyl), 127.7 (C-thiophene), 128.3, 129.0 (2), 130.1 (2), 130.3 (2),
132.1, 133.6 (C-phenyl), 138.3 (C-thiophene), 139.5 (C-phenyl), 148.7 (C=N), 154.8
(C–NH2), 166.2 (CO). Anal. Calcd. For C22H21ClN4O3S2 (489.01): C, 54.03; H, 4.33;
N, 11.46; Found: C, 54.44; H, 4.49; N, 11.61.
N-(4-(1-(2-(2-Amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-
carbonyl)hydrazono)ethyl)phenyl)-4-chlorobenzenesulfonamide (12)
To a solution mixture of compound 4 (3.9 g, 0.01 mol), absolute ethanol (15 mL),
triethylamine 5 drops and cyclohexanone (0.98 g, 0.01 mol), elemental sulfur
(0.32 g, 0.01 mol) were added. The reaction mixture was refluxed for 2 h, then
poured into ice-water and filtered. The solid obtained was crystallized from dioxane
to give 12. Yield, 79.1%; m.p. 138–140 °C. IR (KBr, cm-1): 3387, 3332, 3262
(2NH, NH2), 3078 (CH arom.), 2930, 2857 (CH aliph.), 1680 (CO), 1603 (C=N),
1
1335, 1191 (SO2), 739 (C–Cl). H-NMR (400 MHz, DMSO-d6) d: 1.63, 2.44 (m,
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Anticancer and radio-sensitizing evaluation of some new…
8H, 4 CH2 cyclohexane), 2.14 (s, 3H, CH3), 7.06–7.82 (m, 8H, Ar–H), 7.53 (s, 1H,
SO2NH), 10.62 (s, 1H, NH), 10.96 (s, 2H, NH2). 13C-NMR (100 MHz, DMSO-d6)
d: 24.4 (CH3), 25.3 (2), 26.9 (2) (CH2 cyclohexane), 119.7 (C–CO), 127.7 (2) (C-
phenyl), 127.7 (C-thiophene), 128.3, 129.0 (2), 130.1 (2), 130.3 (2), 132.1, 133.6
(C-phenyl), 138.3 (C-thiophene), 139.5 (C-phenyl), 148.7 (C=N), 154.8 (C–NH2),
166.2 (CO). Anal. Calcd. For C23H23ClN4O3S2 (503.04): C, 54.92; H, 4.61; N,
11.14; Found: C, 55.23; H, 4.93; N, 11.37.
In vitro anticancer evaluation against human tumor liver cancer (HepG2)
The in vitro anticancer screening was performed on liver human carcinoma cell line
(HepG2) using the sulforhodamine B stain (SRB) assay for 26 new compounds and
one reported compound. The in vitro anticancer screening was done by the
pharmacology unit at the National Cancer Institute, Cairo University.
The sulforhodamine B (SRB) assay [31], remains one of the most widely used
methods for in vitro cytotoxic screening. It relies on the ability of SRB to bind to
protein components of the cells that have been fixed to tissue-culture plates by
trichloroacetic acid (TCA). The amount of dye extracted from stained cells is
equivalent to the cell mass [32]. Cells were plated in the 96-multiwell plate (104
cells/well) for 24 h before adding the target compounds. Compounds were added to
1 mL DMSO and diluted with saline to make serial dilutions of the target
compounds (12.5, 25, 50, and 100 lM). Triplicate wells were prepared for
concentration to determine the standard error. Color intensity was measured using
enzyme-linked immunosorbent assay (ELISA) reader. The relationship between
surviving fraction and drug concentration was plotted to get the IC50 of the
compound after the specified time, and compared to the reference drug doxorubicin,
the results are given in Table 1.
Radiosensitizing evaluation
Irradiation of the promising compounds was performed at the National Center for
Radiation Research and Technology, Egyptian Atomic Energy Authority, using
Gamma cell-40 (137Cs) source. The most active compounds 4, 8d and 8h were
further re-evaluated for their in vitro cytotoxic activity in combination with c-
irradiation (8 Gy). Cells were incubated in the 96-multiwell plate for 24 h before c-
irradiation with a single dose of 8 Gy. Cells were further incubated for 48 h at
37 °C in 5% CO2 atmosphere. After that, cells were fixed, washed and stained with
0.4% (wt/vol) SRB dissolved in 1% acetic acid, for 30 min. Excess unbound dye
was washed off four times using 1% acetic acid and the attached stain was recovered
with Tris–EDTA buffer. Color intensity was measured at a wavelength of 570 nm.
In another plate, cells were incubated with the most potent compounds: 4, 8d, and
8h in molar concentrations of 12.5, 25, 50, and 100 lM. After 2 h, cells were
subjected to a single dose of c-radiation at a dose level of 8 Gy with a dose rate of
0.758 rad/s for 18 min, then cytotoxicity was measured 48 h after irradiation. The
surviving fractions were measured and expressed as mean values SE. The results
were analyzed using 1-way ANOVA test and the results are given in Table 2.
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M. M. Ghorab et al.
Table 1 IC50 values of the newly synthesized compounds against HepG2 cell line
Cpd. no.
Compound concentration (lM)
IC50 (lM)
Surviving fraction (mean SE)a
12.5 (lM)
25 (lM)
50 (lM)
100 (lM)
DOX.
4
0.551 0.026
0.180 0.056
0.731 0.032
0.688 0.021
0.688 0.029
0.844 0.027
0.881 0.009
0.625 0.024
0.819 0.023
0.812 0.031
0.725 0.015
0.625 0.026
0.719 0.027
0.762 0.011
0.750 0.021
0.906 0.027
0.844 0.009
0.564 0.015
0.615 0.023
0.623 0.032
0.667 0.015
0.513 0.023
0.667 0.024
0.646 0.019
0.844 0.011
0.744 0.030
0.769 0.032
0.694 0.023
0.480 0.003
0.159 0.025
0.594 0.049
0.625 0.029
0.625 0.022
0.719 0.032
0.563 0.006
0.625 0.098
0.688 0.033
0.563 0.014
0.606 0.016
0.624 0.020
0.625 0.032
0.700 0.008
0.740 0.012
0.750 0.032
0.563 0.031
0.359 0.098
0.359 0.033
0.419 0.016
0.513 0.007
0.506 0.020
0.395 0.032
0.395 0.006
0.613 0.024
0.531 0.014
0.688 0.034
0.563 0.008
0.139 0.005
0.078 0.008
0.444 0.017
0.500 0.024
0.608 0.028
0.438 0.025
0.438 0.018
0.469 0.013
0.375 0.010
0.419 0.016
0.400 0.014
0.344 0.018
0.563 0.020
0.438 0.027
0.438 0.028
0.500 0.020
0.469 0.018
0.308 0.003
0.333 0.017
0.383 0.018
0.256 0.010
0.308 0.018
0.349 0.020
0.297 0.018
0.463 0.012
0.431 0.027
0.406 0.018
0.500 0.013
0.130 0.016
0.064 0.044
0.321 0.022
0.434 0.024
0.563 0.015
0.393 0.007
0.402 0.011
0.447 0.034
0.291 0.055
0.364 0.036
0.296 0.026
0.234 0.015
0.468 0.039
0.412 0.011
0.407 0.015
0.441 0.006
0.423 0.031
0.283 0.034
0.292 0.019
0.314 0.015
0.224 0.004
0.289 0.015
0.298 0.015
0.279 0.031
0.428 0.004
0.409 0.010
0.372 0.006
0.451 0.007
32
8
5
41.2
50
6
7a
7b
7c
7d
7e
7f
–
44.4
38.2
45
40.3
36.2
37.9
36
7g
7h
7i
–
7j
44.3
45
8a
8b
8c
8d
8e
8f
50
42
16.4
18.2
18.4
26.3
13.3
19
8g
8h
8i
8j
19.7
43.8
33.3
41.7
50
9
10
11
12
a
Each value is equivalent to the mean of three experiments SE
Molecular modeling and docking
The molecular model of the new compounds was built using standard bond angles
and lengths, with the MOE software suite 2007.09. Following geometry optimiza-
tion, energy minimization was carried out to employing the ConfSearch module in
MOE. All molecular mechanics calculations were performed with the Merck Force
Field (MMFF94 s). The crystallographic structure of CA II/IX mimic complex was
obtained from the Protein DataBank, with PDB ID: 4BCW. Hydrogen was added to
123

Anticancer and radio-sensitizing evaluation of some new…
Table 2 IC50 values of compounds 4, 8d, and 8h against HepG2 cell line in combination with c-radiation
Cpd. Control Irradiated
no.
Compound concentration (lM) ? irradiation (8 Gy)
IC50
(lM)
(8 Gy)
Surviving fraction (mean SE)a
12.5
25
50
100
4
1.000
1.000
1.000
0.927 0.02* 0.26 0.08* 0.25 0.01* 0.12 0.01* 0.11 0.01*
6.5
8d
8h
0.927 0.02* 0.42 0.01* 0.34 0.02* 0.28 0.01* 0.11 0.01* 10.7
0.927 0.02* 0.28 0.02* 0.25 0.01* 0.18 0.01* 0.11 0.01* 9.1
* Significant difference from control group at p \ 0.001
a
Each value is equivalent to the mean of three values SE
the enzyme and partial charges were deliberated. Validation followed by docking of
the new compounds into the active site were carried out, after removing the co-
crystallized ligand. The target protein was kept rigid, while the added ligands were
left free to explore the conformational space inside the enzyme cavity; 50 separate
docking simulations were run using default parameters and the conformations were
chosen based on the E conformation, S score data, and appropriate fitting with the
relevant amino acids in the binding pocket.
Results and discussion
Chemistry
Schemes 1, 2, and 3 showed the synthetic strategies utilized for the synthesis of the
target compounds (5–12) from the starting material 4-Chloro-N-(4-(1-(2-(2-
cyanoacetyl)hydrazono)ethyl)phenyl) benzenesulfonamide 4 [33]. Reaction of 4
with malononitrile and/or ethyl cyanoacetate in dioxane to give 4-chloro-N-(4-(1-
((4,6-diamino-3-cyano-2-oxopyridin-1(2H)-yl)imino)ethyl)phenyl) benzenesulfon-
amide 5 and N-(4-(1-((4-amino-3-cyano-6-hydroxy-2-oxopyridin-1(2H)-yl)imi-
no)ethyl)phenyl)-4-chlorobenzenesulfonamide 6, respectively (Scheme 1). IR of 5
1
revealed bands at 3334 and 3283 cm-1 for the introduced NH2 groups. H-NMR
displayed up-field singlet at 4.16 ppm assigned to the (CH-pyridone) and two
downfield shifted singlets appearing at 10.6 and 10.94 ppm, due to two NH2
protons. 13C-NMR exhibited a new up-field signal at 88.5 ppm for the (CH-
pyridone), 138.3 ppm for (N–C–NH2) and 166.2 ppm for C–NH2. IR of 6 revealed
bands at 3420, 3237, and 3210 cm-1 for the OH and NH2 groups. 1H-NMR
displayed an up-field singlet at 4.18 ppm for the (CH-pyridone), and two downfield
shifted singlets appearing at 10.62 and 10.96 ppm, for the NH2 and OH protons.
13C-NMR exhibited a new up-field signal at 75.5 ppm for the (CH-pyridone),
165.3 ppm for the (C–OH) and 166.2 ppm for the (C–NH2).
The reaction of 4 with a series of aromatic aldehydes yielded the corresponding
hydrazone derivatives 7a–j (Scheme 2), that was further reacted with malononitrile
in ethanol containing piperidine to give the corresponding 1,2-dihydropyridone
123

M. M. Ghorab et al.
Scheme 1 Synthesis of the pyridone derivatives 5, 6
derivatives 8a–j. Another pathway for the preparation of 8a–j was carried out
through the reaction of 4 with the corresponding arylidene malononitrile in ethanol
1
containing piperidine (Scheme 2). H-NMR of 7a–j displayed a downfield shifted
singlet corresponding to the CH and the disappearance of the CH2 peak of 4. While,
13C-NMR exhibited a new signal corresponding to the CH. IR of 8a–j revealed
bands for the NH2 and (2CN) groups at their characteristic regions. 1H-NMR
displayed a downfield shifted singlet attributed to the NH2 protons and the
disappearance of CH2 and NH peaks of 4.
Alternatively, malononitrile and/or ethyl cyanoacetate were reacted with 4 in the
presence of elemental sulfur and in absolute ethanol containing triethylamine to
yield the thiophene derivatives 9 and 10 (Scheme 3). This reaction goes in parallel
to Gewald’s thiophene synthesis [34]. IR of 9 and 10 revealed bands for the NH2
1
groups. H-NMR of 9 displayed two downfield shifted singlets appearing at 7.79
and 10.95 ppm, for the two NH2 protons. 13C-NMR exhibited new signals at
115.3 ppm for (C-thiophene), 132.2 ppm for (C–NH2) and 166.2 ppm for (S–C–
1
NH2). IR of 10 revealed the band at 1742 cm-1 for the (CO) group. H-NMR
123

Anticancer and radio-sensitizing evaluation of some new…
Scheme 2 Synthesis of the hydrazone 7a–j and pyridone 8a–j derivatives
displayed up-field triplet at 1.03 ppm for the CH3, quartet at 4.17 ppm for the CH2
and two singlets at 7.79 and 10.95 ppm for the two NH2 protons. 13C-NMR
exhibited two up-field signals at 20.1, 60.3 ppm for the CH3 and CH2 ester,
123

M. M. Ghorab et al.
Scheme 3 Synthesis of the thiophene and fused thiophene derivatives 9–12
respectively. Also, new signals at 119.7, 126.0, 132.2, and 163.5 corresponding to
(C-thiophene), (C–CO ester), (C–NH2), and (CO ester), respectively. The reaction
of 4 with cyclopentanone and cyclohexanone together with elemental sulfur yielded
the corresponding N-(4-(1-(2-(2-amino-5,6-dihydro-4H-cyclopenta[b]thiophene-3-
carbonyl)hydrazono)ethyl)phenyl)-4-chlorobenzenesulfonamide 11 and N-(4-(1-(2-
(2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonyl)hydrazono)ethyl)phenyl)-4-
chlorobenzenesulfonamide 12, respectively. The reaction proceeded according to
the reported method [35] (Scheme 3).
In vitro anticancer evaluation against human tumor liver cancer (HepG2)
A closure look to the in vitro cytotoxic results of the target compounds in Table 1, it
was found that the cyanoacetohydrazone derivative 4 showed the most potent
activity (IC50 8 lM). The formation of the 3-cyanopyridone derivatives 5 and 6
provided less active derivatives compared to doxorubicin (IC50 41.2, 50 lM),
respectively. Where 5 is more active than its isoster 6.
The 3-aryl acryloyl hydrazono derivatives 7a–j also provided either less potent or
nearly equipotent derivatives compared to the reference drug, (IC50 36.2–45 lM).
Compounds 7a and 7i showed no activity, compound 7f with 3-(4-methoxyphenyl)
substitution is the most potent derivative in this series (IC50 36.2 lM).
Concerning the 3,5-dicyanopyridone derivatives 8a–j, it was found that the 4-aryl
substituent greatly affected their activity. Compounds 8d–j (IC50 16.4, 18.2, 18.4,
26.3, 13.3, 19.0, and 19.7 lM, respectively) showed better activity compared to
doxorubicin. The most active derivative is 8h with a 4-chlorophenyl substituent
(IC50 13.3 lM), followed by 8d with a 4-styrylbenzene substituent (IC50 16.4 lM).
123

Anticancer and radio-sensitizing evaluation of some new…
The formation of the thiophene 9, 10 and the fused thiophene derivatives 11, 12
resulted in either equipotent or less active derivatives compared to doxorubicin
(IC50 33.3–50 lM). The thiophene-3-carboxylate derivative 10 is the most active in
this series and nearly equipotent to doxorubicin (IC50 33.3 lM).
Radiosensitizing evaluation
The radiosensitizing ability of the most active compounds 4, 8d, and 8h was
studied. From the results obtained in Table 2, compound 4 showed the IC50 value of
8 lM, when the cells were subjected to the compound alone. But, when the cells
were subjected to the same concentrations of compound 4 and irradiated with a
single dose of 8 Gy c-radiation, the IC50 value was significantly decreased to
6.5 lM. Similarly, compound 8d showed the IC50 value of 16.4 lM before
irradiation, that was converted to 10.7 lM after irradiation, and compound 8h
showed the IC50 value of 13.3 lM before irradiation, that was decreased to 9.1 lM,
after irradiation. The results proved the ability of the synthesized compounds to
sensitize cancer cells to the destructive effect of ionizing radiation in order to
decrease the dose of the drug and its toxicity as well. The change in IC50 (lM) for
compounds 4, 8d, and 8h against HepG2 after irradiation is illustrated in Table 2.
Molecular modeling and docking study
To provide a rationale for the cytotoxic activity of the newly synthesized
compounds, a molecular modeling study was carried out on CA II/IX mimic
receptor (PDB ID: 4BCW) [36]. The first real CA IX X-ray structure was reported
by Alterio et al. (PDB ID: 3IAI) [37], followed by CA II/IX mimic receptor (PDB
ID: 4BCW), then another three structures (PDB IDs: 5FL4, 5FL5, and 5FL6) [38].
CA II/IX mimic receptor composed of a dimer, each monomer of which consists of
10-stranded antiparallel sheets forming the core of the molecule [36, 39]. The
binding pocket contains a Zn(II) ion, which is crucial for activity, in coordination
with His 94, 96, 119, and a water molecule. The essential amino acids in the binding
pocket are the proton alternate residues involved in the binding with inhibitors [36].
The active site contains both hydrophobic and hydrophilic regions, at which the
different substitutions of the sulfonamide derivative bind to.
Initially, docking validation was performed to ensure the ability of the docking
protocol to recognize the active site and reproduce the docking results. A
conformational search using an implicit solvent model was achieved for the
prepared compounds, followed by geometry refinement of the local minima through
a quantum–mechanical (QM) method. Then, docking of the newly synthesized
compounds was performed in the CA II/IX mimic active site co-crystallized with a
sulfonamide native ligand (E)-2-(5-bromo-2-hydroxyphenyl) ethane sulfonic acid,
obtained from the Protein DataBank (PDB ID: 4BCW) [36].
Docking of all the synthesized compounds was performed and the results are
shown in Table 3. The poses obtained for the new sulfonamide derivatives were
found to bind in a co-crystallized ligand-like manner (Figs. 2, 3, 4). herein the
findings obtained for the three most active compounds in this study. 3D ligand
123

M. M. Ghorab et al.
Table 3 Binding interactions and energy scores of all the synthesized compounds inside CA II/IX mimic
active site
˚
Length (A)
Compound
Amino acids
Interacting groups
Energy score
(S) (kcal/mol)
Ligand
4
Zn
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
NH
2.12
2.71
2.08
3.08
1.51
2.70
2.79
1.38
1.90
3.02
2.03
2.21
2.36
2.53
2.28
2.51
1.88
2.22
2.13
3.01
2.59
2.52
2.31
3.10
1.78
2.72
2.70
3.02
1.73
2.01
2.54
1.97
2.94
2.34
2.16
2.33
2.52
3.00
1.98
2.12
-14.04
-10.92
Thr 199
Zn
His 94
His 96
His 119
Thr 199
Zn
5
-9.88
His 64
His 94
His 96
His 119
Thr 199
Zn
C=N
NH
SO2
SO2
SO2
SO2
SO2
SO2
SO2
NH
6
-9.12
-9.01
His 94
His 119
Thr 199
Zn
7a
His 96
His 119
Thr 199
Thr 199
Zn
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
NH
7b
-8.98
His 94
His 96
His 119
Thr 199
Zn
7c
-9.13
-9.68
His 96
His 119
Thr 199
Zn
SO2
SO2
SO2
C=N
NH
7d
His 94
His 96
His 119
Thr 199
Zn
SO2
SO2
SO2
SO2
SO2
SO2
7e
-9.41
His 94
His 96
His 119
123

Anticancer and radio-sensitizing evaluation of some new…
Table 3 continued
˚
Length (A)
Compound
Amino acids
Interacting groups
Energy score
(S) (kcal/mol)
Thr 199
Zn
SO2
SO2
NH
2.79
2.42
2.78
2.59
1.99
2.54
2.48
2.79
1.63
3.05
3.00
2.64
2.74
2.36
2.83
2.38
2.16
2.58
1.76
3.04
2.58
2.04
1.76
3.06
2.89
3.01
2.50
2.64
2.38
2.11
2.38
1.50
1.77
3.00
2.23
2.71
2.65
2.16
1.96
2.37
7f
-8.49
-8.99
-8.88
-9.11
His 96
Thr 199
Zn
SO2
SO2
NH
7g
7h
7i
His 96
Thr 199
Zn
SO2
SO2
NH
His 96
Thr 199
Zn
SO2
SO2
C=N
NH
His 94
His 96
His 119
Thr 199
Zn
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
NH
7j
-9.21
-8.41
His 94
His 96
His 119
Thr 199
Zn
8a
His 94
His 96
Thr 199
Zn
8b
8c
-7.99
-8.95
Thr 199
Zn
His 96
His 119
Thr 199
Zn
SO2
SO2
SO2
NH2
NH
8d
-9.98
Gln 67
His 64
His 94
His 96
His 119
Thr 199
Thr 199
Zn
C=N
NH
SO2
SO2
SO2
SO2
NH2
8e
-9.18
Gln 67
123

M. M. Ghorab et al.
Table 3 continued
˚
Length (A)
Compound
Amino acids
Interacting groups
Energy score
(S) (kcal/mol)
His 96
Thr 199
Zn
SO2
SO2
SO2
NH2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
NH2
SO2
SO2
SO2
SO2
SO2
NH2
SO2
SO2
SO2
SO2
NH2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
SO2
NH
1.65
2.12
2.12
2.93
2.66
2.11
3.03
2.81
2.41
2.75
1.94
3.01
2.18
2.47
2.15
1.69
3.01
2.18
2.43
2.14
2.47
1.62
2.53
2.31
3.04
1.77
2.67
1.81
2.56
1.84
2.32
2.48
2.39
2.08
2.82
1.76
2.61
2.57
2.72
2.27
8f
-9.21
-8.62
Gln 67
His 96
Thr 199
Zn
8g
His 94
His 96
His 119
Thr 199
Zn
8h
-9.22
-8.42
His 94
His 96
His 119
Thr 199
Zn
8i
Gln 67
His 94
His 96
His 119
Thr 199
Zn
8j
-9.42
Gln 67
His 96
His 119
Thr 199
Zn
9
-7.98
-8.35
Gln 67
His 96
Thr 199
Zn
10
His 96
Thr 199
Zn
11
12
-8.97
-9.10
Thr 199
Zn
His 96
His 119
Thr 199
SO2
SO2
123

Anticancer and radio-sensitizing evaluation of some new…
Fig. 2 3D docking of 8d (S = -9.98 kcal mol-1) in the active site of 4BCW
Fig. 3 2D ligand interaction of 8d with the active site amino acids of 4BCW
interactions of compound 8d (Fig. 2) showed that the compound binds in the same
manner as the co-crystallized ligand with a binding score of -9.98 kcal mol-1
.
While, the 2D ligand interactions (Fig. 3) demonstrated that the 8d binds with the
amino acids Thr199, His119, His96, His64, and Gln67, as well as the Zn atom
through a network of hydrogen bonds, with an average bond length between 1.77
˚
and 2.71 A. Simultaneously, the 2D ligand interactions of 8h (Fig. 4) showed that it
binds in the same fashion to the native ligand displaying a set of hydrogen bonds
123

M. M. Ghorab et al.
Fig. 4 2D ligand interaction of 8h with the active site amino acids of 4BCW
with the amino acids Thr199, His119, His96, and His94, as well as Zn interactions
and binding energy of -9.22 kcal mol-1 (Table 3).
These remarkable interactions between CA II/IX mimic active site and the new
derivatives might explain their cytotoxic activity. Further investigations to explore
more the possible mechanism of action of these derivatives are underway.
Conclusion
In summary, a novel series of sulfonamide derivatives containing pyridone,
hydrazone, thiophene, and fused thiophene moieties were synthesized. These
compounds were designed and synthesized as potential carbonic anhydrase
inhibitors (CAIs) and were evaluated for their anticancer activity against human
liver carcinoma cell line (HepG2). Compounds 4, 8d–j were found to be more
potent than doxorubicin. From the results, we can conclude that the introduction of
cyanoacetohydrazone moiety is associated with enhanced anticancer activity and
gave the most potent derivative in this study 4 (IC50 = 8.0 lM). The combination
of a sulfonamide with 3,5-dicyanopyridone moiety having different 4-aryl
substitution as in compounds 8d and 8h gave less potent derivatives than 4, but
still more potent than doxorubicin (IC50 = 16.4 and 13.3 lM). Moreover, the most
active compounds 4, 8d and 8h showed an enhanced radio-sensitizing activity when
evaluated for their in vitro anticancer activity in combination with c-radiation. Also,
the molecular modeling showed that all the docked compounds exhibited similar
and additional binding interactions as those previously reported by the co-
crystallized ligand when docked into CA II/IX mimic active site, which suggests
that these compounds may possibly act as CA inhibitors and this may contribute to
their anticancer activity.
123

Anticancer and radio-sensitizing evaluation of some new…
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