New diarylureas and diarylamides possessing acet(benz)amidophenyl scaffold: Design, synthesis, and antiproliferative activity against melanoma cell line

Article abstract of DOI:10.1016/j.bmcl.2012.03.020

A series of new diarylurea and diarylamide derivatives possessing acet(benz)amidophenyl scaffold was synthesized. Their in vitro antiproliferative activity was tested against A375P human melanoma cell line. Compounds 1c,d and 2c,d showed the highest potencies with IC₅₀ values in sub-micromolar scale. In addition, compounds 1b,e,l and 2e,l were more potent than Sorafenib but with IC₅₀ values in micromolar range. Moreover, compound 2c was equipotent to Vemurafenib, and 2d showed higher potency than Vemurafenib against A375P. Molar refractometry calculation and ADME profiling of the highest potent four derivatives 1c,d and 2c,d are also reported.

Full text of DOI:10.1016/j.bmcl.2012.03.020

Bioorganic & Medicinal Chemistry Letters 22 (2012) 3269–3273
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
New diarylureas and diarylamides possessing acet(benz)amidophenyl
scaffold: Design, synthesis, and antiproliferative activity against melanoma
cell line
Hee Jin Kim a, Hye Jung Cho a, Hwan Kim a, Mohammed I. El-Gamal b,c, Chang-Hyun Oh b,c, So Ha Lee a,
Taebo Sim a, Jung-Mi Hah d, Kyung Ho Yoo a,
⇑
a Chemical Kinomics Research Center, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-650, Republic of Korea
b Center for Biomaterials, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-650, Republic of Korea
c Department of Biomolecular Science, University of Science and Technology, 113 Gwahangno, Yuseong-gu, Daejeon 305-333, Republic of Korea
d Department of Pharmacy, College of Pharmacy, Hanyang University 1271 Sa 3-dong, Sangnok-gu, Ansan-si, Gyunggi-do 426-791, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of new diarylurea and diarylamide derivatives possessing acet(benz)amidophenyl scaffold was
synthesized. Their in vitro antiproliferative activity was tested against A375P human melanoma cell line.
Compounds 1c,d and 2c,d showed the highest potencies with IC50 values in sub-micromolar scale. In
addition, compounds 1b,e,l and 2e,l were more potent than Sorafenib but with IC50 values in micromolar
range. Moreover, compound 2c was equipotent to Vemurafenib, and 2d showed higher potency than
Vemurafenib against A375P. Molar refractometry calculation and ADME profiling of the highest potent
four derivatives 1c,d and 2c,d are also reported.
Received 20 January 2012
Revised 21 February 2012
Accepted 6 March 2012
Available online 11 March 2012
Keywords:
Melanoma
Antiproliferative activity
Acet(benz)amidophenyl
Diarylurea
Ó 2012 Elsevier Ltd. All rights reserved.
Diarylamide
A375P
Melanoma is a malignant tumor that arises from melanocytic
cells and primarily involves the skin. Exposure to solar ultraviolet
irradiation, fair skin, dysplastic nevi syndrome, and a family history
of melanoma are major risk factors for melanoma development.
Melanomas can metastasize either by the lymphatic or by the
ative agents against melanoma cell lines.8–17 Sorafenib (NexavarÒ)
is a diarylurea derivative that has been extensively used in clinical
trials.18 Encouraged by the interesting antiproliferative activity of
diarylurea and diarylamide derivatives, we synthesized a new ser-
ies of diarylureas and diarylamides containing acet(benz)amid-
ophenyl scaffold (Fig. 1). Their in vitro antiproliferative activity
against A375P human melanoma cell line is reported. In addition,
molar refractometry and ADME predictions of the most potent tar-
get compounds are also reported.
The target compounds 1–4 were synthesized according to the
sequence of reactions illustrated in Scheme 1. Heating a solution
of 2-methyl-5-nitrobenzenamine (5) in acetic anhydride afforded
the acetamido intermediate 6.19 Treatment of 5 with benzoyl chlo-
ride gave the benzamido compound 7. Reduction of the nitro group
of 6, 7 using palladium over carbon in hydrogen atmosphere pro-
duced the corresponding amino derivatives 8, 9 in good yields.
Interaction of the amino groups of 8, 9 with the appropriate aryl
isocyanate led to formation of the target diarylurea derivatives
1a–l and 2a–l, respectively. Synthesis of the diarylamides 3a–e
and 4a–e was carried out by condensation of the amino groups
of 8, 9 with the appropriate carboxylic acid derivatives in the pres-
ence of HOBt, EDCI, and triethylamine.
hematogenous route.1 Metastatic melanoma is
a particularly
aggressive form of cancer that is resistant to standard anticancer
therapies. Early stage melanoma (stage I/II) primary tumors can
be surgically resected with more than 95% success rate.2 In con-
trast, late-stage (stage IV) metastatic melanoma is one of the most
deadly forms of cancer, with the median survival of patients with
distant metastases being 7–8 months.3 With the rapid incidence
of melanoma in the United States and other developed countries,
there is an urgent need to develop more effective drugs.4–6
In 2011, Vemurafenib (PLX4032, ZelborafÒ) was approved by
the US food and drug administration (FDA) for treatment of late-
stage melanoma.7 In addition, a number of reports have recently
highlighted diarylureas and diarylamides as potential antiprolifer-
⇑
Corresponding author. Address: Biomolecular Functional Research Center,
Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-
650, Republic of Korea. Tel.: +82 2 958 5152; fax: +82 2 958 5189.
E-mail address: khyoo@kist.re.kr (K.H. Yoo).
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.03.020

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H. J. Kim et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3269–3273
F
H
N
H
N
Cl
O
CF3
Cl
O
O
O
S
N
O
H
N
R1
N
H
N
H
R2
N
H
O
F
O
N
O
N
H
R1 = CH3, C6H5
R2 = Ar, ArNH
Vemurafenib
Sorafenib
Figure 1. Structures of Vemurafenib, Sorafenib, and the target compounds.
O
O
i
O
O
ii
iii
R2
R1
N
H
NO2
H2N
NO2
R1
N
H
NH2
R1
N
H
N
H
N
H
5
R1 = CH3
R1 = CH3
R1 = CH3, R2 = (hetero)aromatics
8
9
6
7
1a-l
2a-l
R1 = C6H5
R1 = C6H5
R1 = C6H5, R2 = (hetero)aromatics
iv
O
O
R1
N
H
N
H
R2
R1 = CH3, R2 = (hetero)aromatics
3a-e
4a-e
R1 = C6H5, R2 = (hetero)aromatics
Scheme 1. Reagents and conditions: (i) (CH3CO)2O, 90 °C, 3 h, 78% (for 6), C6H5COCl, CH2Cl2, rt, 3 h, 69% (for 7); (ii) Pd/C, H2, MeOH, rt, 2 h, 93% (for 8), 85% (for 9); (iii) R2-
NCO, THF, rt, 4 h, 5–76% (for 1a–l), 54–64% (for 2a–l); (iv) R2-CO2H, HOBt, EDCI, Et3N, DMF, 90 °C, 12 h, 22–73% (for 3a–e), 25–64% (for 4a–e).
The antiproliferative activity of the newly synthesized com-
pounds against A375P human melanoma cell line was tested. The
ability of acet(benz)amidophenylurea and diarylamide derivatives
to inhibit the growth of A375P cell line is summarized in Tables 1
and 2. Sorafenib was selected as a reference standard because it
has been extensively used in clinical trials for treatment of mela-
noma.4,20 Vemurafenib was also utilized as a second reference
standard in this experiment because of its high potency against
melanoma cell lines,21 and it has been recently approved by the
FDA for treatment of advanced melanoma.7
Compounds 1d,e and 2d,e with urea linker were more potent
than the corresponding compounds 3a,b and 4a,b with amide
group as a linker. In general, the urea compounds in Table 1 dem-
onstrated higher potencies than compounds in Table 2 with amide
linker. This may be attributed to that the longer spacer, urea moi-
ety, may geometrically permit appropriate fitting of the molecule
at the receptor site. Or the terminal NH group of the urea moiety
may form additional hydrogen bond(s) at the receptor site. Any
or both of these effects would enable optimal drug–receptor inter-
action, and hence higher antiproliferative activity.
The effect of substituents of the terminal aryl ring on potency
was also investigated. Compounds 1b and 2b with terminal 3,4-
dichlorophenyl ring were more potent than 1g and 2g with 3,4-
dimethylphenyl moiety. So we may conclude that electron-with-
drawing groups on the terminal ring are more favorable for activity
than electron-donating groups. In addition, 3,5-dichlorophenyl
derivatives 1c and 2c showed higher potencies than 1b and 2b
with 3,4-dichlorophenyl ring. This may be attributed to different
directions of the terminal groups at the receptor site, which may
affect the drug-receptor interaction. Moreover, compounds 1d
and 2d with 3,5-bis(trifluoromethyl)phenyl, in addition to 1e and
2e with 4-chloro-3-(trifluoromethyl)phenyl ring were more potent
than 1f and 2f with 3-fluoro-5-(trifluoromethyl)phenyl ring. This
indicates that fluoro substituent on the terminal ring is unfavor-
able for activity.
tent derivatives of this series, with IC50 values in sub-micromolar
range. So it can be concluded that these terminal rings together
with urea spacer are optimum for antiproliferative activity of this
series of compounds against melanoma cells. In addition, benz-
amido derivatives 2c and 2d were found to be more potent than
acetamido compounds 1c and 1d. This may be due to hydrophobic
interaction and/or electronic differences between benzamido phe-
nyl ring and acetamido methyl group, which may affect the drug–
receptor interaction.
Compounds 1b (with 3,4-dichlorophenyl terminal ring), 1e, 2e
(with 4-chloro-3-(trifluoromethyl)phenyl ring), and 1l, 2l (with
chloropyridyl ring) were more potent than Sorafenib but with
IC50 values in micromolar scale. These terminal aryl moieties to-
gether with 3,5-dichlorophenyl and 3,5-bis(trifluoromethyl)phenyl
are the optimal moieties for this series of compounds.
As compared with Vemurafenib, compound 2c demonstrated
the same potency. And compound 2d showed 1.57 times higher
potency against A375P than Vemurafenib.
The influence of steric factors on the antiproliferative activity
was investigated. Molar refractometry (MR, steric parameter) val-
ues were determined for the compounds with the highest poten-
cies 1c,d and 2c,d, and are presented in Table 3. The benzamido
compounds 2c,d with the highest MR values showed the highest
potency over A375P melanoma cell lines. And the acetamido deriv-
atives 1c,d with lower bulkiness and MR values were less potent
against A375P, compared with 2c,d. From these results, we can
conclude that MR and bulkiness are directly proportional to the
antiproliferative activity of this series of compounds. The bulkier
benzamido moiety may enable the appropriate fitting at the recep-
tor site, and hence higher antiproliferative activity.
The bioavailability of compounds 1c,d and 2c,d was assessed
using ADME (absorption, distribution, metabolism, and excretion)
prediction methods. In particular, we calculated the compliance
of compounds to the Lipinski’s rule of five.22 This approach has
been widely used as a filter for substances that would likely be fur-
ther developed in drug design programs. In addition, we calculated
the total polar surface area (TPSA) since it is another key property
that has been linked to drug bioavailability. Thus, passively ab-
Among all the target compounds, it was found that urea com-
pounds 1c and 2c with 3,5-dichlorophenyl terminal ring, and 1d
and 2d with 3,5-bis(trifluoromethyl)phenyl ring are the most po-

H. J. Kim et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3269–3273
3271
Table 1
Antiproliferative activity of acetamidophenylureas 1a–l and benzamidophenylureas 2a–l
O
O
R2
R1
N
H
N
H
N
H
Compd No.
R1
R2
A375P (IC50
>30
,
lM)
Compd No.
R1
R2
A375P (IC50
>30
, lM)
Cl
Cl
1a
CH3
2a
C6H5
Cl
Cl
Cl
Cl
1b
1c
CH3
CH3
2.1
2b
2c
C6H5
C6H5
5.8
Cl
Cl
0.561
0.259
Cl
Cl
CF3
CF3
1d
1e
1f
CH3
CH3
CH3
0.685
1.1
2d
2e
2f
C6H5
C6H5
C6H5
0.162
1.3
CF3
Cl
CF3
Cl
CF3
CF3
F
F
>30
>30
CF3
CF3
1g
1h
CH3
CH3
>30
2g
2h
C6H5
C6H5
>30
9.8
22.1
O
O
1i
1j
CH3
CH3
>30
>30
2i
2j
C6H5
C6H5
>30
>30
O
O
O
O
O
O
O
O
1k
CH3
CH3
>30
2k
C6H5
C6H5
>30
O
O
Cl
Cl
1l
1.1
2.7
2l
1.6
N
N
Sorafenib
Vemurafenib
0.254
sorbed molecules with a TPSA >140 are thought to have low oral
bioavailability.23 Molecules violating more than one of these rules
may have problems with bioavailability. Predictions of ADME
properties for the studied compounds are summarized in Table 3.
The results showed that all the four tested compounds comply
with these rules. Theoretically, compounds 1c,d and 2c,d should
present good passive oral absorption and differences in their bioac-
tivity cannot be attributed to this property.
In conclusion, a series of new acet(benz)amidophenylurea and
bisamide derivatives was synthesized based on our previous liter-
ature studies, and as a continuation of our ongoing anticancer
development program. Among all of these derivatives, compounds
1b–e, 1l, 2c–e, and 2l demonstrated higher potencies against
A375P human melanoma cell line than that of Sorafenib. Of special
interest, compounds 1c24 and 2c possessing 3,5-dichlorophenylu-
rea, in addition to 1d and 2d24 with 3,5-bis(trifluoromethyl)phe-
nylurea moiety showed the highest potencies with IC50 values in
sub-micromolar scale. Among them, compound 2c showed the
same potency and 2d was more potent, compared with Vemurafe-
nib. Molar refractometry calculations showed that the increased
bulkiness induced by benzamido moiety, in case of compounds
2c,d, was favorable for activity. In silico ADME profiling showed
that compounds 1c,d and 2c,d can be bioavailable through passive
oral absorption. The superior potency of compound 2d against

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H. J. Kim et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3269–3273
Table 2
Antiproliferative activity of the bisamides 3a–e and 4a–e
O
O
R1
N
H
N
H
R2
Compd No.
R1
R2
A375P (IC50
,
lM)
Compd No.
R1
R2
A375P (IC50, lM)
CF3
CF3
CF3
CF3
3a
CH3
>30
4a
C6H5
>30
CF3
CF3
3b
3c
3d
CH3
CH3
CH3
>30
12.9
>30
4b
4c
4d
C6H5
C6H5
C6H5
>30
>30
>30
Cl
O
Cl
O
O
O
N
O
N
O
O
O
O
O
3e
CH3
>30
2.7
4e
C6H5
>30
Sorafenib
Vemurafenib
0.254
Table 3
Molar refractometry, solubility, and calculated Lipinski’s rule of five for the most potent target compounds
Compd No.
IC50 (nM) over A375P cell linea
MRb
LogSc
Parameter
LogPd
TPSAe
MWf
nONg
nOHNHh
nViolations
1c
1d
2c
2d
561
685
259
162
89.72
ꢀ5.80
ꢀ5.89
ꢀ6.97
ꢀ7.06
3.02
3.75
4.92
5.65
70.23
70.23
70.23
70.23
352.22
419.32
414.28
481.39
5
5
5
5
3
3
3
3
0
0
0
0
93.52
109.84
113.64
a
b
c
Data taken from Table 1.
Molar refractometry (cm3/mol).
Solubility parameter.
d
e
f
Calculated lipophilicity.
0
Total polar surface area (AÅ2).
Molecular weight.
g
h
Number of hydrogen bond acceptors.
Number of hydrogen bond donors.
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Acknowledgments
This research was supported by Korea Institute of Science and
Technology (KIST) and Fundamental R&D Program for Core Tech-
nology of Materials funded by the Ministry of Knowledge Economy,
Republic of Korea (K0006028).
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24. Selected data. Compound 1c: 1H NMR (400 MHz, DMSO-d6) d 9.23 (s, 1H), 8.96
(s, 1H), 8.85 (s, 1H), 7.57 (d, J = 1.4 Hz, 1H), 7.54 (d, J = 1.8 Hz, 1H), 7.52 (d,
J = 1.8 Hz, 2H), 7.19 (t, J = 1.8 Hz, 1H), 7.17 (d, 2.1 Hz, 1H), 7.14 (t, J = 1.8 Hz,
1H), 7.08 (d, J = 8.3 Hz, 1H), 2.13 (s, 3H), 2.05 (s, 3H); MS m/z 353 (M+1)+.
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J = 7.3 Hz, 2H), 7.07 (q, J = 3.7 Hz, 2H), 2.30 (s, 3H); MS m/z 482 (M+1)+.