Novel diarylsulfonylurea derivatives as potent antimitotic agents

Article abstract of DOI:10.1016/j.bmcl.2004.09.069

Novel diarylsulfonylurea derivatives have been synthesized and identified as potent inhibitors of tubulin polymerization and cancer cell proliferation. Furthermore, these compounds were also efficacious against multidrug-resistant cancer cells. A novel series of diarylsulfonylurea derivatives were synthesized and evaluated for interaction with tubulin and for cytotoxicity against human cancer cell lines. These derivatives demonstrated good inhibitory activity against tubulin polymerization, which was well correlated with promising antiproliferative activity as well as G2/M phase cell cycle arrest. Furthermore, several compounds were also efficacious against multidrug-resistant cancer cells, which are resistant to many other known microtubule inhibitors.

Full text of DOI:10.1016/j.bmcl.2004.09.069

Bioorganic & Medicinal Chemistry Letters 14 (2004) 6075–6078
Novel diarylsulfonylurea derivatives as potent antimitotic agents
Semi Kim,a,* Ji Hyun Park,a Sun-Young Koo,a Jung In Kim,a Min-Hyeung Kim,a
Ji Eun Kim,a Kiwon Jo,a Hwan Geun Choi,a Sung Bae Leea and Sang-Hun Jungb
aLG Life Sciences, Ltd/R&D Park, 104-1 Moonji-dong, Yuseong-gu, Daejon 305-380, South Korea
bCollege of Pharmacy, Chung-Nam National University, Daejon 305-764, South Korea
Received 18 August 2004; revised 17 September 2004; accepted 21 September 2004
Available online 14 October 2004
Abstract—A novel series of diarylsulfonylurea derivatives were synthesized and evaluated for interaction with tubulin and for cyto-
toxicity against human cancer cell lines. These derivatives demonstrated good inhibitory activity against tubulin polymerization,
which was well correlated with promising antiproliferative activity as well as G2/M phase cell cycle arrest. Furthermore, several
compounds were also efficacious against multidrug-resistant cancer cells, which are resistant to many other known microtubule
inhibitors.
Ó 2004 Elsevier Ltd. All rights reserved.
Tubulin, the major protein component of microtubules,
is the target of numerous antimitotic drugs.1–3 Microtu-
bules play an important role in a variety of cellular proc-
esses, including mitosis and cell division.4–6 Various
antimitotic agents interfering with the natural dynamics
of tubulin polymerization and depolymerization inhibit
cancer cell proliferation.2,3,7
are effective in treating multidrug-resistant (MDR)
tumors.
Diarylsulfonylureas represent a new class of antitumor
agents with a broad spectrum of activity against rodent
and human models of cancer in vivo.11–13 The precise
mechanism of antitumor action has not been elucidated.
Some prototypic compounds, such as sulofenur and
LY295501 (Fig. 1) have been studied in clinical trials.
However, the development of sulofenur was precluded
by dose-limiting toxicities including methemoglobine-
mia and hemolytic anemia,14,15 whereas LY295501
recently showed improved side effects with a specific
pattern of myelotoxicity and paucity of nonhematologi-
cal toxicity.16 Further modification of diarylsulfonyl-
ureas is continuing as promising anticancer activity
and some clinical benefit have made the development
of structural analogues the focus of much research.
Hwang et al.17 have reported a novel derivative of diaryl-
sulfonylurea, DW2282 (Fig. 1), which strongly
Antimitotic agents largely fall into three major classes.
The taxanes such as paclitaxel and docetaxel stabilize
microtubules by preventing the depolymerization of tub-
ulin.1,2 The Vinca alkaloids (e.g., vincristine, vinblastine,
and vinorelbine) and colchicine inhibit the polymeriza-
tion of tubulin.1,2 Disruption of tubulin dynamics leads
to cell cycle arrest in the G2/M phase and induction of
apoptosis.5,8 Although antimitotic compounds such as
paclitaxel and vinblastine have been used clinically in
the treatment of different cancers, a major drawback
of taxanes and Vinca alkaloids in clinical application
is the development of drug resistance through the
expression of efflux pumps, including P-glycoprotein
(Pgp) and multidrug resistance-associated protein
MRP.9,10 Therefore, there is a high medical demand to
find and develop small molecule tubulin inhibitors that
O
O
O
S
O
O
O
N
S
HN
N
N
H
Cl
H
N
Y
X
O
NH2
Keywords: Diarylsulfonylurea; Antimitotic; Tubulin inhibitor; Antitu-
mor; MDR.
X = H, Y = CH2 Sulofenur
X = Cl, Y = O LY295501
DW2282
*
Corresponding author. Tel.: +82 42 866 2221; fax: +82 42 861
2566; e-mail: semikim@lgls.co.kr
Figure 1. Structures of diarylsulfonylureas.
0960-894X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2004.09.069

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S. Kim et al. / Bioorg. Med. Chem. Lett. 14 (2004) 6075–6078
suppressed the growth of human tumors in vitro and in
vivo.18 The precise mode of action of DW2282 remains
unclear, however.
a - c
d
O
F
NH2
e, f
OPh
OMs
HN
R1
OH
R1
NH2
CO2H
Here, we report a new series of diarylsulfonylurea deriv-
atives as new potent antimitotic agents. Numerous
derivatives of DW2282 were synthesized and evaluated
for interaction with tubulin and for cytotoxicity against
human cancer cell lines. These new derivatives demon-
strated good inhibitory activity against tubulin polymer-
ization, which was well correlated with in vitro
antiproliferative activity as well as G2/M phase cell cycle
arrest. Furthermore, several of the new derivatives re-
ported here maintain activity against multidrug-resistant
tumor cell lines, which indicates that they are not sub-
strates for P-glycoprotein mediated transport. These
findings indicate that these newly synthesized diaryl-
sulfonylurea derivatives represent promising new anti-
mitotic agents that inhibit tubulin polymerization with
efficacy against multidrug-resistant tumor cells.
R
R = (S)-Ph, Thiophen-2-yl
R1 = (S)-Ph, 4-F-Ph
Thiophen-2-yl
Scheme 1. Synthesis of methanesulfonates. Reagents and conditions:
(a) m-CPBA, CH2Cl2, rt; (b) NaN3, NH4Cl, aq MeOH, 60°C; (c) 10%
Pd/C, MeOH, rt; (d) LiAlH4, THF, reflux; (e) PhOCOCl, NaHCO3, aq
THF, rt; (f) MsCl, Et3N, CH2Cl2, rt.
H2NSO2
a - c
N
H
N
CF3
O
R1
H2NSO2
R1
a - c
Novel derivatives of diarylsulfonylurea DW2282 were
synthesized as shown in Schemes 1–3 (Table 1). All these
compounds were characterized by physical and spectral
analysis data that confirmed the assigned structures.
These new derivatives were evaluated for inhibition of
tubulin polymerization and antiproliferative activity
against human cancer cell lines. The in vitro tubulin
polymerization reaction was evaluated turbidimetri-
cally.19 As shown in Table 1, compounds 1e, h, and j
showed little inhibitory activity in tubulin polymeriza-
tion assay and compounds 1b and m displayed weak
activity. However, compounds 1f, k, 2a, and b had mod-
erate activity, whereas compounds 1c and l had modest
activity. Compounds 1d, g, i as well as DW2282 dis-
played strong inhibitory activity against tubulin poly-
merization. Compound 1a proved to be the most
potent tubulin polymerization inhibitor, comparable to
vincristine. The antiproliferative activity of these new
synthetics was assessed using human colon carcinoma
(HCT116), and human non-small cell lung cancer cell
lines (A549, and NCI-H460). After 48h continuous drug
exposure, the concentration required for 50% growth
inhibition (GI50) was determined by the sulforhodamine
B (SRB) colorimetric assay.20 These derivatives dis-
NH2
NH
O
CF3
R1 = Me, Cl
Scheme 2. Synthesis of arylsulfonamides. Reagents and conditions: (a)
(CF3CO)2O, Py., CH2Cl2, 0°C; (b) ClSO3H, 60°C; (c) NH3, CH2Cl2,
rt.
played promising in vitro antiproliferative activity with
GI50 values in the low micromolar to nanomolar con-
centration range (Table 1). In general, a good correla-
tion was found between inhibition of tubulin
polymerization and cytotoxicity. Among these deriva-
tives, compound 1d acted as a very potent cell growth
inhibitor with GI50s similar to those of DW2282. Com-
pound 1a, showing the most potent tubulin polymeriza-
tion inhibitory activity, displayed the most significant
antiproliferative effect (average GI50 = 7nM), compar-
able to those of paclitaxel and vincristine.
The effect on cell cycle progression of selected com-
pounds (1b–d, paclitaxel) was also examined using flow
cytometry.21 MCF7 cells were exposed to different
concentrations of the compounds for 16h. At 1lM
O
O O
S
H2NSO2
O
O
O O
S
a
c, d, e or f
N
N
HN
R1
OPh
OMs
HN
R1
HN
R1
N
+
+
N
N
H
CF3
O
R2
O
1
O
O
S
O
O
O O
S
R1
O
R1
R1
H2NSO2
N
HN
N
a, b
c or f
HN
HN
Ph
OPh
OMs
NH2
NH
CF3
NH
R2
O
O
2
Scheme 3. Synthesis of diarylsulfonylurea derivatives. Reagents and conditions: (a) NaOH, DMF, 0°C ꢀ rt; (b) NaBH4, EtOH, 0°C; (c) R2COCl,
Py., CH2Cl2, rt; (d) BrCOCH2Br, Py., CH2Cl2, rt; PhNH2, K2CO3, DMF, rt; (e) triphosgene, Et3N, CH2Cl2, 0°C; c-HexylNH2, 2-(morpholin-4-
yl)ethylamine or 2-(4-methyl-piperazin-1-yl)ethanol, rt; (f) p-NO2-BzCl, Py., CH2Cl2, rt; Raney-Ni, MeOH, rt.

S. Kim et al. / Bioorg. Med. Chem. Lett. 14 (2004) 6075–6078
6077
Table 1. Inhibition of tubulin polymerization and cellular proliferation for new diarylsulfonylurea derivatives, DW2282, vincristine, and paclitaxel
O
O
O
O
O
O
R1
S
S
N
N
HN
R1
HN
N
NH
R2
O
O
R2
1
2
Compound
R1
R2
ITPa IC50 (lM)
Cell line, GI50 (lM)b
HCT116
A549
NCI-H460
1a
1b
(S)-Ph
(S)-Ph
CH2-thiophen-2-yl
<1 (82)c
22
0.006
0.386
0.089
0.019
0.27
0.007
0.386
0.133
0.028
0.95
0.08
0.065
2.8
0.007
0.7
2,6-Dichloropyridin-4-yl
Pyridin-4-yl
Thiophen-2-yl
1c
1d
(S)-Ph
(S)-Ph
10.3
1.6
0.09
0.022
0.95
0.15
0.08
1.0
1e
(S)-Ph
(S)-Ph
5-Nitrofuran-2-yl
CH2NHPh
NH-cyclohexyl
40
1f
1g
3.5
0.055
0.05
1.2
(S)-Ph
(S)-Ph
2
30
1h
1i
NH(CH2)2-morpholin-4-yl
OEt
(S)-Ph
(S)-Ph
1.5
0.08
1.0
0.08
1.0
0.08
0.9
1j
1k
O(CH2)2-4-methylpiperazin-1-yl
Furan-2-yl
30
Thiophen-2-yl
Thiophen-2-yl
4-Fluorophenyl
Me
4
10.5
0.075
0.3
1.1
0.062
0.18
1.2
0.064
0.25
0.9
1l
1m
4-Aminophenyl
4-Aminophenyl
OEt
25
2a
2b
6
5.5
0.07
0.06
0.048
0.06
0.02
0.027
0.013
0.07
0.06
0.022
0.003
0.007
Cl
4-Aminophenyl
DW2282
Vincristine
Paclitaxel
1.5
0.012
0.001
<0.001
<1 (83)c
<1d (80)c
a ITP = inhibition of tubulin polymerization, evaluated as described in Ref. 19. A minimum of two independent determinations were performed with
each compound. The IC50 value represents the concentration that inhibits the extent of assembly by 50% after 30min at 37°C.
b All experiments were performed at least in triplicate using the SRB assay as described in Ref. 20, and GI50 data were calculated from dose–response
curves by nonlinear regression analysis.
c Numbers in parentheses represent the percentage of inhibition or induction of polymerization at 1lM.
d Concentration that induces tubulin polymerization by 50% in the absence of GTP after 30min at 37°C.
concentration of each compound, a clear shift from G1
to G2/M phase was observed (Fig. 2A). Thus, com-
pounds 1b–d induce an accumulation of MCF7 cells
specifically in the G2/M phase of the cell cycle, similar
to the known G2/M cell cycle inhibitor paclitaxel. When
the percentage of cells arrested in the G2/M phase was
plotted against different concentrations of the com-
pounds, compounds 1b–d arrested the cell cycle in a
concentration-dependent manner with IC50 values of
0.3, 0.1, and 0.03lM, respectively (Fig. 2B). G2/M
arrest of these compounds increased in parallel with
both tubulin polymerization inhibition and antiprolifer-
ative activity. This consistency indicates that the G2/M
phase arrest of the compounds is probably induced by
inhibition of tubulin polymerization, which is also corre-
lated with cell growth inhibition. Taken together, these
results demonstrate that this series is a potent anti-
mitotic agent inhibiting tubulin polymerization with
promising antiproliferative activity.
To quantitatively express the effect of MDRphenotype
on the cytotoxicity of each compound, resistance factor
(rF) was calculated by dividing the GI50 value observed
with resistant cell line MCF7/ADRwith that observed
with parental cell line MCF7. As shown in Table 2, com-
pounds 1f, 2a, and 2b strongly maintained their activity
against the multidrug-resistant MCF7/ADRcell_line
(rF ꢀ 1). They were also similarly active against three
other MDRtumor cell lines. In contrast, DW2282
(rF = 133) and compound 1g (rF = 8.7) were less active
against MCF7/ADRthan against the parent cell line.
The A498 cell line was also relatively resistant to
DW2282 and compound 1g. Paclitaxel was markedly
less toxic toward the MCF7/ADRcell line relative to
the parent cell line (rF = 727) and not highly active
against other MDRtumor cell lines. This observation
indicates that some of these derivatives are efficacious
against multidrug-resistant tumor cell lines and are not
substrates of Pgp-mediated transport.
In order to investigate the effects of the derivatives on
MDRtumor cell lines, several compounds were evalu-
ated against MCF7, MCF7/ADR, HCT-15, A498, and
NCI-H226 cancer cell lines (Table 2). The MCF7/
In summary, we have synthesized novel derivatives of
diarylsulfonylurea and have found these compounds to
be potent antimitotic agents. These compounds have po-
tent in vitro tumor growth inhibitory activity correlated
with inhibition of tubulin polymerization and are also
efficacious against multidrug-resistant cancer cells.
Thus, this series represents a new class of antimitotic
ADRcell line is derived from MCF7 cell line and exhib-
22
its the MDRphenotype.
H226 are all Pgp-expressing MDRtumor cell lines.
HCT-15, A498, and NCI-
23

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S. Kim et al. / Bioorg. Med. Chem. Lett. 14 (2004) 6075–6078
References and notes
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Figure 2. Effect on cell cycle progression. MCF7 cells were treated with
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Compound
Cell line, GI50 (lM)a
MCF7b MCF7/
ADRc (rFd)
0.18 (1.2)
HCT-15c A498c NCI-
H226c
1f
1g
0.15
0.15
0.15
0.15
0.015
0.011
0.1
0.15
0.7
0.15
0.08
0.45
0.15
0.1
1.3 (8.7)
0.15 (1.0)
0.15 (1.0)
2 (133)
0.12
0.1
2a
2b
0.13
0.06
1.2
0.11
0.12
0.3
DW2282
Paclitaxel
8 (727)
3.5
20
a All experiments were performed at least in triplicate using the SRB
assay as described in Ref 20.
b MDR( À), not multidrug resistant.
c MDR(+), multidrug resistant.
d rF = resistance factor, calculated from the ratio of GI50 for MCF7/
ADRand that for MCF7.
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agents distinct from previous diarylsulfonylurea com-
pounds. Further investigation of the SARof this series
is ongoing and will be reported in due course.