Design, synthesis and biological activities of sorafenib derivatives as antitumor agents

Article abstract of DOI:10.1016/j.bmcl.2012.09.031

A series of novel sorafenib derivatives, 9a-w, was designed and synthesized in high yields using various substituted anilines, and their antiproliferative activities against HCT116, PC-3 and MDA-MB-231 cell lines were also evaluated and described. All compounds exhibited potent antiproliferative activity against HCT116 and PC-3 cells with IC₅₀ = 2.8-52.0 and 2.2-45.6 μM; compounds 9p and 9q demonstrated competitive antiproliferative activities to sorafenib against all three cancer cell lines, the cytotoxicity of compound 9r is more potent than that of sorafenib. Compounds (9g, 9p, 9q and 9r) were chosen for further evaluation of the anti-angiogenesis activity, and showed the inhibition of sprout formation from aortic ring ex vivo. The structures of all the newly synthesized compounds were determined by ¹H NMR, ¹³C NMR and HRMS.

Full text of DOI:10.1016/j.bmcl.2012.09.031

Bioorganic & Medicinal Chemistry Letters 22 (2012) 6549–6553
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Design, synthesis and biological activities of sorafenib derivatives
as antitumor agents
Jianwen Yao a,b, Zuopeng He a, Jing Chen a, Wei Sun b, Hao Fang b, Wenfang Xu b,
⇑
a Department of Medicinal Chemistry, School of Pharmacy, Yantai University, 30 Qingquan Road, Yantai, Shandong 264005, PR China
b Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Shandong University, 44 West Culture Road, Jinan, Shandong 250012, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 21 July 2012
Revised 19 August 2012
Accepted 11 September 2012
Available online 19 September 2012
A series of novel sorafenib derivatives, 9a–w, was designed and synthesized in high yields using various
substituted anilines, and their antiproliferative activities against HCT116, PC-3 and MDA-MB-231 cell
lines were also evaluated and described. All compounds exhibited potent antiproliferative activity against
HCT116 and PC-3 cells with IC50 = 2.8–52.0 and 2.2–45.6 lM; compounds 9p and 9q demonstrated com-
petitive antiproliferative activities to sorafenib against all three cancer cell lines, the cytotoxicity of com-
pound 9r is more potent than that of sorafenib. Compounds (9g, 9p, 9q and 9r) were chosen for further
evaluation of the anti-angiogenesis activity, and showed the inhibition of sprout formation from aortic
ring ex vivo. The structures of all the newly synthesized compounds were determined by 1H NMR, 13C
NMR and HRMS.
Keywords:
Sorafenib analogs
Antiproliferative activity
Synthesis
Ó 2012 Elsevier Ltd. All rights reserved.
Anti-angiogenesis activity
Sorafenib (NexavarÒ, BAY 43-9006), the first multikinase inhib-
itor for the treatment of advanced renal cell carcinoma (RCC), was
proved to block tumor proliferation and angiogenesis by inhibiting
Raf, VEGFR, PDGFR and KIT.1–4 Although sorafenib has the advanta-
ges of broad-spectrum anticancer potency, safety and less prone to
resistance, it still has some disadvantages such as poor physico-
chemical properties5 and poor therapeutic activity in the treatment
of malignant melanoma,6 hence more and more attentions are
given to the optimization of sorafenib.5,7–10
Targeted compounds were prepared as outlined in Scheme 1. 2-
Picolinic acid 1 reacted with SOCl2 to generate 4-chloropicolinoyl
chloride 2, which was treated with methanol to get methyl
4-chloropicolinate 3. Then the corresponding amines(methylamine,
H
N
H
N
F3C
Cl
N
B
A
C
O
NH
Weak inhibitory activity of sorafenib against V600EB-Raf may be
the main reason causing the poor therapeutic activity to mela-
noma.11 To improve upon sorafenib in terms of both V600EBRAF
potency and cell growth inhibition, Holladay et al.12 reported a
series of sorafenib derivatives with 1,3-substituted on B ring which
showed superior activity against B-Raf. We have previously de-
scribed a series of diaryl thiourea derivatives with 1,4-substituted
on B ring based on the bioisosteric theory (Fig. 1).13 In the present
paper, a series of sorafenib derivatives with 1,3-substituted on B
ring (9a–w) were designed and synthesized (Fig. 1). The antiprolif-
erative activities of 23 compounds against human colorectal
carcinoma cell line (HCT116), human breast cancer cell line
(MDA-MB-231) and human prostate cell line (PC-3) were evalu-
ated, and the anti-angiogenesis ex vivo of some compounds were
also investigated.
O
Sorafenib
HCT116 IC50 = 7.8 μ M
O
R
H
N
H
N
Ar
N
B
C
4
S
O
O
previously reported compounds
HCT116 IC50 = 9.2-53.2 μ M
R
H
N
H
N
O
3
Ar
O
B
C
S
N
9a-w
HCT116 IC50 = 2.8-52.0 μ M
⇑
Corresponding author. Tel./fax: +86 531 88382264.
E-mail address: wfxu@yahoo.cn (W. Xu).
Figure 1. Structures of sorafenib and its derivatives.
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.09.031

6550
J. Yao et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6549–6553
Cl
Cl
b
a
N
1
COOH
N
2
COCl
H2N
N
3
COOCH3
Cl
N
O
O
c
d
R1
R1
N
O
R2
H
N
H
N
O
O
R1
g
4a-4g
5a-5g
S
N
R2
R2
R2
S
C
e
f
H
N
9a-9w
SH
NCS
NH2
6a-6f
8a-8f
7a-7f
Scheme 1. Reagents and conditions: (a) SOCl2; (b) CH3OH; (c) RNH2/pyrrolidine, THF; (d) 3-aminophenol, DMF, t-BuOK; (e) Dabco, CS2, toluene; (f) BTC, DCM; (g) DCM.
ethylamine, 2-propylamine, phenylmethanamine, cyclopropyl-
amine, cyclohexylamine and pyrrolidine) were reacted with 3 to
form 4a–g, which were treated with 3-aminophenol to afford corre-
sponding diaromatic ethers (5a–g) in the total yields of 41.2–62.1%.
Various isothiocyanates (8a–f) were obtained from substituted
anilines (2,4-dichloroaniline, 4-chloroaniline, 3,4-difluoroaniline,
3-(trifluoromethyl)aniline, 4-chloro-3-(trifluoromethyl)aniline or
4-(trifluoromethoxy)aniline), 6a–f, which reacted with CS2 to gener-
ate 7a–f, and then treated with BTC to produce various isothiocya-
nates 8a–f. Finally, these isothiocyanates were reacted with
different substituted diaryl ethers (5a–g) to give target compounds
(9a–w) in 26.3–54.4% total yields (see Supplementary data, experi-
mental methods).
to 1,3 should enhance the cytotoxicity of the diaryl thiourea
derivatives. In our previous study (the B-ring of the compounds
is 1,4-disubstituted), only the compounds with R1 being
methylamino group showed the inhibitory activity against
MDA-MB-231 cell, while in this study, the derivatives with other
substitutes could also inhibit the growth of MDA-MB-231 cell. Fur-
thermore, large R1 group may improve the cytotoxicity of the com-
pounds against PC-3 and HCT116 cells. This trait is also different
from that of the compounds reported previously. For example,
the compounds (9d, 9l, 9m, 9r and 9v) with R1 being benzylamino
or cyclohexylamino group had more potent antiproliferative activ-
ity to PC-3 and HCT-116 cells compared with compounds contain-
ing other substitutes, while the compounds with methylamino
substitute showed relatively weak activity. The effect of the substi-
tutes on the terminal phenyl ring is similar to that of our previ-
ously reported compounds. 3-CF3, 4-Cl-disubstituted on the
phenyl ring is important to the cytotoxicity of the derivatives.
For example, all 3-CF3, 4-Cl-disubstituted compounds showed
potent cytotoxicity against MDA-MB-231 cell with IC50 = 21.2–
In vitro cell cytotoxicity of the 23 new sorafenib derivatives was
initially evaluated against HCT116, MDA-MB-231 and PC-3 cells by
MTT assay using sorafenib as a positive control. As shown in Table
1, all compounds exhibited potent antiproliferative activity against
HCT116 and PC-3 cells with IC50 = 2.8–52.0 and 2.2–45.6 lM; 11
compounds demonstrated significant inhibitory activities against
all three cell lines; compounds 9p and 9q demonstrated competi-
tive antiproliferative activities to sorafenib; compound 9r showed
superior activity against all three cancer cell lines to sorafenib. In
general, these compounds had more potent activities to cancer
cells than the compounds reported previously,13 which indicated
that the change in the substitution pattern of the B ring from 1,4
40.2 lM,) which values are also better than those (29.7–122.5
lM) of previously reported compounds.
To further investigate the anti-angiogenesis activity of the
derivatives, we also examined the sprouting of vessels from aortic
rings in the presence of compounds (9g, 9p, 9q, 9r) which have po-
tent cytotoxicity to cancer cells. As shown in Figure 2, sorafenib
Table 1
The structures and IC50 values of the target compounds
R1
H
N
H
N
O
Ar
O
S
N
a
Compd. No.
Substituent
IC50
(
lM)
Ar
Cl
R1
HCT116
MDA-MB-231
PC-3
H
N Me
9a
41.2 2.1
>100
37.8 2.2
Cl
Cl
Cl
H
9b
9c
39.4 1.9
22.1 2.2
>100
24.1 1.0
21.2 0.9
N Me
H
N
87.5 2.1

J. Yao et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6549–6553
6551
Table 1 (continued)
a
Compd. No.
Substituent
IC50 (lM)
Ar
R1
HCT116
MDA-MB-231
>100
PC-3
NH
Cl
9d
9e
16.5 1.4
15.8 0.9
33.1 2.1
F
F
F
F
H
N Me
30.3 2.1
30.3 2.4
8.9 1.4
52.0 2.6
25.3 1.8
19.4 2.1
20.2 1.0
8.4 1.4
7.5 2.1
19.2 1.9
15.1 1.3
6.9 1.9
9.3 1.0
2.8 0.4
22.4 1.0
>100
F
F
F
F
H
N
9f
>100
26.3 2.7
8.1 2.1
H
N
9g
9h
9i
>100
N
>100
45.6 1.6
24.5 2.2
18.3 1.2
22.1 1.2
16.8 2.0
11.0 0.9
27.0 1.1
16.1 1.1
8.5 1.4
CF3
CF3
CF3
CF3
CF3
CF3
CF3
H
N Me
>100
H
N
9j
53.1 1.8
34.8 1.9
>100
H
N
9k
9l
H
N
NH
N
9m
9n
9o
9p
9q
9r
9s
75.0 2.2
35.4 2.5
35.7 1.2
22.1 1.8
21.2 1.0
34.2 1.5
40.2 1.1
H
N Me
Cl
CF3
H
N
Cl
CF3
H
N
6.8 1.5
Cl
CF3
H
N
2.2 0.4
Cl
CF3
N
12.1 1.9
Cl
H
9t
OCF3
OCF3
33.8 1.1
18.1 1.8
>100
>100
34.7 1.8
11.8 0.9
N Me
H
9u
N
NH
N
OCF3
OCF3
9v
7.4 2.2
>100
6.8 0.8
9w
17.8 1.1
7.8 1.1
37.8 1.2
36.6 2.1
34.1 2.2
6.8 0.9
Sorafenib
—
—
a
Mean value of three experiments and standard deviation are given.

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J. Yao et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6549–6553
Figure 2. Microvessel sprouting ex vivo. Aortic segments isolated from Sprague-Dawley rats were placed in growth factor-reduced Matrigel-covered wells in the absence (a)
or presence of the compounds (0.1 M; b. sorafenib, c. 9g, d. 9p, e. 9q, f. 9r) for 6 d.
l
can completely inhibit blood vessel formation at the concentration
of 0.1 M; 9g and 9p demonstrate the significantly inhibition
Acknowledgments
l
against blood vessel formation; 9r can partly block the formation
of blood vessel; while the inhibitory ability of 9q is unconspicuous.
It should be noted that 9q and 9r are the best compounds against
all three cell line, but their anti-angiogenesis activity is poor, which
indicate that these compounds may have different protein targets
compared to sorafenib, which need further investigation.
This work was supported by National Science and Technology
Major Project (Grant No. 2009-ZX09103-118) and Ph.D. Programs
Foundation of Ministry of Education of China (No. 20110131110037).
Supplementary data
In summary, we report herein the synthesis and biological eval-
uation of 23 new sorafenib derivatives as potential antitumor
agents. This series of derivatives demonstrated higher selectivity
towards HCT116 and PC-3 compared with MDA-MB-231. Large
R1 group may improve the cytotoxicity of the series against PC-3
and HCT116 cells. Furthermore, the potent derivatives (9g, 9p,
9q, 9r) were tested for their anti-angiogenesis activity, and com-
pounds 9g and 9p exhibit significant inhibition against blood ves-
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2012.09.031.
These data include MOL files and InChiKeys of the most important
compounds described in this article.
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