Discovery of novel dual inhibitors of VEGFR and PI3K kinases containing 2-ureidothiazole scaffold

Article abstract of DOI:10.1016/j.cclet.2015.09.008

A series of compounds possessing 2-(3-phenyl)ureidothiazol-4-formamide derivatives with a 2-ureidothiazole scaffold were designed and synthesized. Some compounds demonstrated inhibition of cell proliferation against both MDA-MB-231 and HepG2 cell lines using Sorafenib as the positive control. Compounds 6i showed a good to moderate inhibition on VEGFR-2 and PI3Kα which was proved by further molecular docking study. This study suggests that compound 6i is a potential dual inhibitor of VEGFR-2 and PI3Kα and is applicable for further investigation.

Full text of DOI:10.1016/j.cclet.2015.09.008

G Model
CCLET 3431 1–6
Chinese Chemical Letters xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
1
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Original article
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Discovery of novel dual inhibitors of VEGFR and PI3K kinases
containing 2-ureidothiazole scaffold
*
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Q1 Lin Li a,c, Cun-Long Zhang a,c, Hong-Rui Song b, Chun-Yan Tan a,c, Huai-Wei Ding a,b,
,
Yu-Yang Jiang a,c,
*
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a Department of Chemistry, Tsinghua University, Beijing 100084, China
b School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110000, China
Q2 c The Graduate School at Shenzhen, Tsinghua University, Shenzhen 518000, China
A R T I C L E I N F O
A B S T R A C T
Article history:
A series of compounds possessing 2-(3-phenyl) ureidothiazol-4-formamide derivatives with a 2-
ureidothiazole scaffold were designed and synthesized. Some compounds demonstrated inhibition of
cell proliferation against both MDA-MB-231 and HepG2 cell lines using Sorafenib as the positive control.
Received 22 April 2015
Received in revised form 15 May 2015
Accepted 10 August 2015
Available online xxx
Compounds 6i showed a good to moderate inhibition on VEGFR-2 and PI3K
further molecular docking study. This study suggests that compound 6i is a potential dual inhibitor of
VEGFR-2 and PI3K and is applicable for further investigation.
a which was proved by
a
Keywords:
2-Aminothiazole
VEGFR
ß 2015 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
Published by Elsevier B.V. All rights reserved.
PI3K
Anticancer
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1. Introduction
The phosphatidylinositol 3-kinases (PI3Ks) are members of a 29
unique group of intracellular lipid kinases [6]. The PI3K family is 30
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Angiogenesis,theprocessbywhichnewbloodvesselsgrowfrom
a body’s vasculature, is fundamental to physiological processes of
reproduction and wound healing. Disturbances in this process are
associated with pathological conditions like rheumatoid arthritis,
age-related macular degeneration, diabetic retinopathy, and are
highlyrelated to tumorprogression and metastasis[1,2]. Ithas been
confirmedthatblocking angiogenesisis anefficientand prospective
approach for cancer therapy. VEGFRs (vascular endothelial growth
factor receptors) are key regulatory and signaling molecules
involved in angiogenesis and consist of three subtypes: VEGFR-1,
VEGFR-2, and VEGFR-3 [3]. Overexpression of VEGFRs serves as a
potential target for anticancer agents. In other words, a drug can be
designed based on the overexpressed genetic marker. Currently an
extensive array of VEGFR inhibitors is entering clinics and/or
achieving approval from FDA, such as bevacizumab, sorafenib,
sunitinib, pazopanib and vandetanib, while many are still in
preclinical development [4,5].
involved in numerous cellular functions including proliferation, 31
adhesion, migtation, invasion, metabolism and survival [7]. Fre- 32
quent occurrences of aberrant signaling mediated by PI3Ks in 33
human cancers have made them attractive targets for the design of 34
small molecule inhibitors.
35
Although antiangiogenesis has shown to be a promising 36
strategy for cancer therapy, VEGFR inhibitors often encounter 37
resistance to novel therapeutic agents or chemotherapeutics after 38
a period of treatment. One important explanation is that many 39
other pathways are activated during antiangiogenic treatment to 40
counteract the therapeutic efficacy [8]. The PI3K/Akt signaling 41
pathway is one that has proven to be a bypass or compensatory 42
pathway and can become overactive in the presence of cancers or 43
certain agents [9,10]. PI3Ks upregulate angiogenic cytokines due to 44
tumor hypoxia, or oncogene stimulation, and alter endothelial cell 45
responses to them. These cytokines signal through the receptors 46
VEGFR, FGFR, and Tie-2 to potentiate cell proliferation, migration, 47
differentiation into tubules, and ‘‘invasion’’ of these capillary 48
sprouts into extracellular matrix [11]. Therefore, blocking activa- 49
tion of the PI3K/Akt pathway during antiangiogenesis therapy 50
*
Corresponding authors at: Department of Chemistry, Tsinghua University,
Q3
could reduce tumor progression.
51
Beijing 100084, China.
However, VEGFRs and PI3Ks are from different kinases families 52
so it is a challenge to effectively design dual inhibitors of VEGFRs 53
E-mail addresses: dinghuaiwei627@163.com (H.-W. Ding),
Jiangyuy@mail.tsinghua.edu.cn (Y.-Y. Jiang).
http://dx.doi.org/10.1016/j.cclet.2015.09.008
1001-8417/ß 2015 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.
Please cite this article in press as: L. Li, et al., Discovery of novel dual inhibitors of VEGFR and PI3K kinases containing 2-ureidothiazole
scaffold, Chin. Chem. Lett. (2015), http://dx.doi.org/10.1016/j.cclet.2015.09.008

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and PI3Ks. As of now, there are no reports on an agent that targets
both enzymes. Our investigation was induced by the lack of such
an agent and the possibility of discovering VEGFR and PI3K dual
inhibitors with novel scaffold. With this purpose, we searched the
Ambinter and Chemspider libraries by the combinatory approach
of SVM (support vector machine) and docking and were able to
identify a one hit compound 5a containing imidazo[2,1-b]thiazole
scaffold. Based on this hit compound, a series of 2-aminothiazol-4-
acetamide and 2-aminothiazol-4-carboxamide derivatives was
designed and synthesized. All compounds were evaluated for their
in vitro cytotoxicity against human HepG2 and MDA-MB-231 cell
lines. Kinase inhibition and molecular docking were also studied.
The results showed that compounds 6i and 6j containing 2-
Ureidothiazol scaffold have good PI3K and moderate VEGRF
inhibitory activity along with potency against both MDA-MB-
231 and HepG2 cell lines.
2.2. General procedure for preparation of compounds 2a–2n
85
To a solution of compound ethyl 2-aminothiazole-4-acetate (1)
(10 mmol) or ethyl 2-aminothiazole-4-carboxylate (2) (10 mmol)
in anhydrous THF (10 mL), NMM (15 mmol) and substituted
benzoyl chlorides (11 mmol) or substituted isocyanatobenzenes
(11 mmol) were added with stirring at r.t. for 12 h. The solution
was cautiously basified with 15% NH4OH to pH 7, then poured into
CH2Cl2, separated, washed and concentrated to result in four kinds
of esters 1a–1n, respectively. The crude product 1a–1n was
dissolved in EtOH–H2O–NaOH (700 mL:300 mL:60 g) and refluxed
for another 0.5 h, then acidified to pH 3–4 with concentrated HCl to
afford white solid precipitation. After filtration, wash with water
and dry, the desired compounds 2a–2n were obtained.
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2.3. General procedure for preparation of compounds 3a–3b, 4a–4b
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2. Experimental
A mixture of 2-chloro-5-nitropyridine (3) (50 mmol), morpho-
line (100 mmol), and K2CO3 (100 mmol) in THF (50 mL) were
stirred at 80 C for 4 h. And then the mixture was concentrated to
20 mL and poured into water (100 mL), the yellow solid
precipitation formed. After filtration, wash with purified water
and dry, the desired compound 3a was obtained. 3b Was got with
the same method. The mixture of 3a–3b (20 mmol) and Pd/C (20%,
500 mg) in methanol was hydrogenated at atmosphere at r.t. for
12 h, followed by filtration and concentration to afford compounds
4a–4b.
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2.1. General
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1H NMR, 13C NMR spectra were determined on Bruker ARX-400,
400 Hz spectrometers with tetramethylsilane (TMS) as the internal
standard and DMSO-d6, CDCl3 as the solvent (Chemical shifts in
ppm). Splitting patterns were designated as follows: s: singlet; d:
doublet; t: triplet; m: multiplet. Mass spectra were carried out
using a Waters Micromass Q-TOF Premier Mass Spectrometer.
Melting points were determined in open glass capillaries with a
SGW X-4 digital apparatus and were uncorrected. Follow-up of the
reactions and checking the homogeneity of the compounds were
made by TLC on silica gel-protected glass plates and the spots were
2.4. General procedure for preparation of compound 4c
109
5-amino-2-hydroxybenzoic acid (4) (100 mmol), methanol
(80 mL) and H2SO4 (15 mL) were stirred at 80 C for 24 h, then
cold to r.t. and pale yellow solid precipitation formed. After
filtration, the crude product was dissolved in 200 mL ethyl acetate
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detected by exposure to UV-lamp at
otherwise noted, all solvents and reagents were commercially
available and used without further purification.
l254 and l365. Unless
Table 1
The 2-benzamidothiazole-4-amide derivatives and IC50 values against the liver cancer cell and human breast cancer cell line of compounds 5a–5r.
X
R 4
HN
n
R 5
O
.
O
N
S
R
N
H
5a-5r
Compound
R
R4
R5
X
n
IC50 (mmol/L)
HepG2
MDA-MB-231
5a
5b
5c
5d
5e
Ph
Ph
Ph
Ph
Ph
OCH3
Cl
H
N
1
1
1
1
1
100.0
63.6
25.0
2.7
H
N
NHCH3
OH
H
N
>100
>100
74.4
51.7
39.5
53.7
COOCH3
H
CH
N
N
O
5f
2-chlorophenyl
OCH3
OCH3
OCH3
OCH3
OCH3
Cl
H
N
N
N
N
N
N
N
N
N
N
N
N
CH
1
1
1
1
1
1
1
1
1
1
0
0
0
>100
>100
>100
>100
>100
>100
>100
>100
>100
24.7
12.1
21.1
6.3
5g
3-chlorophenyl
H
5h
4-chlorophenyl
H
5i
3-trifluoromethylphenyl phenyl
2,4-dichlorophenyl
2-chlorophenyl
H
29.4
3.7
5j
H
5k
H
2.5
5l
3-chlorophenyl
Cl
H
18.5
2.4
5m
5n
5o
4-chlorophenyl
Cl
H
2,4-dichlorophenyl
3,4-dichlorophenyl
2,4-dichlorophenyl
2,4-dichlorophenyl
2,4-dichlorophenyl
Cl
H
1.7
Cl
H
9.6
5p
OCH3
Cl
H
85.7
15.2
5.8
5q
H
66.5
5r
OH
COOCH3
45.0
19.4
5.2
Sorafenib
33.7
Please cite this article in press as: L. Li, et al., Discovery of novel dual inhibitors of VEGFR and PI3K kinases containing 2-ureidothiazole
scaffold, Chin. Chem. Lett. (2015), http://dx.doi.org/10.1016/j.cclet.2015.09.008

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and 100 mL H2O. The resulting solution was cautiously basified
with 15% NH4OH to pH 8–9, then separated, washed and
concentrated to get 4c.
3. Results and discussion
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3.1. High-throughput virtual screening
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2.5. General procedure for preparation of compounds 5a–5r, 6a–6o
Virtual screening against Ambinter and in-house libraries was 137
conducted using the similar methods and computational proce- 138
dures as those described in a recently published paper [12– 139
14]. Initially, SVM models of VEGFR and PI3K inhibitors were used 140
to screen the compounds and received many SVM virtual hits. The 141
hits were evaluated by Lipinsky’s rule of five, and compounds that 142
passed Lipinsky’s rule were selected for further screening via 143
molecular docking. Finally, compound 5a (Ambinter ID 15893411) 144
was identified as a virtual multi-target VEGFR and PI3K inhibitor. 145
This compound and the other derivatives of 5a were synthesized. 146
The kinase assay result suggested that 2-aminothiazole is a 147
potential scaffold and can be modified to get novel compounds 148
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A solution of the 2a (1 mmol) and 4a (1 mmol), EDCI (1 mmol),
HOBt (1 mmol), and DIPEA (3 mmol) in anhydrous THF (10 mL)
was stirred for 24 h. The reaction was quenched with 1 M NaOH
(20 mL) and extracted with ethyl acetate (3 Â 20 mL), the organic
layer was washed with 1 mol/L HCl (3 Â 20 mL), water (20 mL),
dried with Na2SO4 and evaporated to give compound 5a as a white
solid. Other title compounds 5b–5r, 6a–6o were synthesized as the
same procedure.
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2.6. Molecular docking methodology
with better antitumor activity.
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The molecular docking of the representative compound 6i
with kinases was carried out using Discovery Studio.3.1/
CDOCKER protocol (Accelrys Software Inc.). The protein crystal-
lographic structure, VEGFR (PDB entry 2QU5) and PI3K (PDB
entry 3L54) were downloaded from the Protein Data Bank (PDB).
The general procedure is as followed: (1) ligand and receptor
preparation, (2) protocol generation, (3) docking and (4) analysis
of the results.
3.2. Chemistry
150
The hit compound 5a and target compounds 5b–5r, 6a–6o 151
collected in Table 1 were prepared as shown in Scheme 1. Ethyl 2- 152
aminothiazole-4-acetate (1) and ethyl 2-aminothiazole-4-carbox- 153
ylate (2) were reacted with substituted benzoyl chlorides and 154
substituted isocyanatobenzenes resulting in four different esters: 155
Scheme 1. Synthesis of compounds 2a–2n, 5a–5r and 6a–6o. Reagents and conditions: (i) THF, substituted benzoyl chlorides, 12 h, r.t.; (ii) EtOH–H2O–NaOH (1.5 mol/L),
reflux, 0.5 h, then HCl (2 mol/L); (iii) amines, DIPEA, HOBt, EDCI, THF, 12 h, r.t.; (iv) THF, substituted isocyanatobenzenes, 12 h, r.t.
Please cite this article in press as: L. Li, et al., Discovery of novel dual inhibitors of VEGFR and PI3K kinases containing 2-ureidothiazole
scaffold, Chin. Chem. Lett. (2015), http://dx.doi.org/10.1016/j.cclet.2015.09.008

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L. Li et al. / Chinese Chemical Letters xxx (2015) xxx–xxx
Scheme 2. Synthesis of compounds 4a–4c. Reagents and conditions: (i) morpholine or methylamine hydrochloride THF, K2CO3, reflux, 4 h; (ii) H2, Pd/C, r.t., 12 h; (iii)
methanol, H2SO4, reflux, 24 h.
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1a–1n. Compounds 1a–1n were directly refluxed in EtOH–H2O–
NaOH and acidified to get 2a–2b [15]. Compounds 3a–3b were
obtained from 2-chloro-5-nitropyridine (3) and other amines as
shown in Scheme 2 [16]. The nitro-group on compounds 3a–3b
was reduced to an amino group by hydrogen using Pd/C as catalyst
at atmospheric pressure and room temperature to get compounds
4a–4b as shown in Scheme 2. 5-Amino-2-hydroxybenzoic acid (4)
was esterified with methanol and catalyzed by H2SO4 to get
compound 4c. The target compounds were prepared via coupling
2a–2n with 4a–4c and other commercially available amines using
DIPEA, HOBt, EDCI [17]. If necessary, silica-gel column chroma-
tography was used with dichloromethane-methanol system as
eluant.
The activity of 5f–5j for the MDA-MB-231 cell line gradually
increased in conjunction with substitutions by 3-chloro, 2-chloro,
4-chloro, and 2,4-chloro on the benzene ring and this sequence
was consistent with the activity of compounds 5k–5n. However,
compound 5o with 3,4-dichloro substituted on benzene ring can
more so increase the activity against HepG2 and decrease the
activity for MDA-MB-231 compared to compound 5n, which was
the 2,4-dichloro substituted on the benzene ring. The activity of
compound 5e showed that pyridine substituted by a bulk group
increased the activity for HepG2 and decreased the activity for
MDA-MB-231 when contrasted to hit compound 5a. After removal
of the methane group to yield derivatives of compound 2, the
activity for HepG2 increased while the activity for MDA-MB-231
remained unaltered, as suggested by 5p vs 5j, 5q vs 5n. In an
attempt to replace the pyridine ring with to get compound 5r, the
activity stayed moderate against the two cell lines. The above
observation indicated that a pyridine ring on position 2 substituted
by a chloro group was crucial for antitumor activity.
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3.3. Biological evaluation
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3.3.1. Antiproliferative activity and Structure-activity relationship
As shown in Table 1, the hit compound 5a and other 2-
benzamidothiazol-4-amide derivatives 5b–5r were evaluated
against HepG2 and MDA-MB-231 cell lines with Sorafenib as
the positive control by MTT assay. The cells were treated with
Based on 2-benzamidothiazole derivatives, a series of 2-(3-
phenyl)ureidothiazole derivatives containing a urea group was
synthesized as listed in Table 2. Overall, the cyototoxicity activity
against HepG2 greatly increased while the activity for MDA-MB-
231 remained constant. Compounds 6f and 6g–6o have IC50 values
compounds in the range of 0.1–100
mmol/L for 48 h.
The results showed that these compounds have selective
inhibition against the MDA-MB-231 cell line compared to the
HepG2 cell line. Five of the compounds that have IC50 values
ranging from 6.4
have IC50 values ranging from 1.6
MB-231. These compounds were more potent than Sorafenib (IC50
33.7 mol/L and 5.2 mol/L, respectively).
m
mol/L to 20.8
m
mol/L for HepG2, and 6d–6o
m
mol/L to 4.6 mol/L for MDA-
m
ranging from 1.7
m
mol/L to 3.7
mmol/L were more potent than
Sorafenib (IC50 5.2
m
mol/L). Compounds 5a, 5f–5j, 5p possess a
m
m
methoxy group while compounds 5b, 5k–5o, 5q possess a chloro
group on position 2 of the pyridine ring. The chloro compounds
were more potent than the corresponding methoxyl derivatives.
SARs suggested that substitution by 3-chloro on the benzene
ring more reactive than the substitution of 4-chloro for HepG2, 6a
vs 6b, and 6d vs 6e. Contrarily, the results for the MDA-MB-231 cell
Table 2
The 2-(3-phenyl) ureidothiazole-4-amide derivatives and IC50 values against the liver cancer cell and human breast cancer cell line of compounds 6a–6o.
H
X
R3
R4
N
N
HN
HN
.
O
O
n
n
O
N
O
N
S
S
R
N
N
R
N
N
H
H
H
H
6a-6m
6n-6o
Compound
R
R3
R4
X
n
IC50 (mmol/L)
HepG2
MDA-MB-231
6a
3-chlorophenyl
4-chlorophenyl
OCH3
OCH3
OCH3
Cl
H
N
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
55.0
>100
>100
45.5
77.7
20.8
>100
8.4
23.1
11.0
14.7
3.6
3.3
2.2
4.3
2.2
3.7
1.6
4.0
4.1
2.6
4.6
3.1
5.2
6b
H
N
6c
3,4-dichlorophenyl
3-chlorophenyl
H
N
6d
H
N
6e
4-chlorophenyl
Cl
H
N
6f
3,4-dichlorophenyl
3,4-dichlorophenyl
3-chlorophenyl
Cl
H
N
6g
OH
OH
OH
Cl
COOCH3
CH
CH
CH
N
6h
6i
COOCH3
3,4-dichlorophenyl
3-chlorophenyl
COOCH3
7.4
6j
H
H
H
H
8.3
6k
3,4-dichlorophenyl
3,4-dichlorophenyl
3,4-dichlorophenyl
3-chlorophenyl
Cl
N
7.5
6l
F
N
6.4
6m
6n
6o
NHCH3
N
26.5
14.7
15.0
33.7
3,4-dichlorophenyl
Sorafenib
Please cite this article in press as: L. Li, et al., Discovery of novel dual inhibitors of VEGFR and PI3K kinases containing 2-ureidothiazole
scaffold, Chin. Chem. Lett. (2015), http://dx.doi.org/10.1016/j.cclet.2015.09.008

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Fig. 1. 2D-presentation for the binding interactions of compound 6i with VEGFR and PI3K kinase domain. (A) Compound 6i with VEGFR; (B) compound 6i with PI3K.
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line were the reverse of the latter. 3,4-Dichloro substituted on
benzene ring increased the activity in both HepG2 and MDA-MB-
231. Similar results were produced for the 2-benzamidothiazole
derivatives in which the chloro group was better than the methoxy
group on position 2 of the pyridine ring.
In order to increase the rigidity of compounds and shorten the
length of the chain, methane was removed in order to synthesize a
series of 2-(3-phenyl) ureidothiazole-4-formamide derivatives
6h–6o. The best results were obtained with compounds 6h–
6l. This may be attributed to hydrogen bond formation at the
receptor site. Basis on compounds 5d, 5r, 6g, compounds 6h, 6i
were synthesized and exhibited good activity in the two cell lines.
Compound 6l was produced by exchanging the chloro group with a
fluoro group on 6k. The activity had no significant increase. We
tried changing the pyridine ring to indazole and received
compounds 6n and 6o, which resulted in decreased activity
against HepG2 and the same activity for MDA-MB-231.
By observing anticancer activity from the data in Table 1 and
Table 2, it was concluded that compounds 5a–5r possess an amide
linker while compounds 6a–6o have a urea group linker. The best
results were obtained with compounds 6h–6l, which exhibited
high potency against HepG2 and MDA-MB-231 cell lines with a
urea linker. It was decided that the urea and 4-formamide are
optimum for this series of compounds against HepG2 and MDA-
MB-231 cell lines.
compound 6f showed moderate PI3Ka inhibitory activity and 253
slightly weaker VEGFR-2 inhibitory activity.
254
3.4. Molecular docking
255
In order to better understand the interaction between 256
compounds and VEGFR and PI3K kinases, compound 6i was 257
selected as a representative example for this series of compounds 258
for molecular docking studies using the Discovery Studio 3.1/ 259
CDOCKER protocol [18,19]. The VEGFR-2 docking study revealed 260
that the 6i formed three strong hydrogen bonds, one
p
–p
261
interaction, and one cation– interaction between the binding site 262
p
and the ligand (Fig. 1A). Two hydrogen bonds were formed 263
between phenolic hydroxyl and CYS919, and the other one was 264
formed between the urea hydrogen atom and GLU885. The
p
–p
265
interaction and cation–
and LYS868, respectively.
p
interaction were formed with PHE918 266
267
Compound 6i was also docked onto the PI3K-binding domain. 268
Fig. 1B demonstrates that the ligand 6i formed three hydrogen 269
bonds with the protein. The phenolic hydroxyl oxygen atom and 270
carbonyl oxygen atom as hydrogen bond acceptor formed two 271
hydrogen bonds with LYS833. Also the urea group as hydrogen 272
bond donors formed one hydrogen bond with VAL882. The docking 273
analysis indicated that compound 6i fit into the binding site of 274
VEGFR and PI3K kinases suggesting that this compound may be a 275
potent VEGFR and PI3K inhibitor.
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3.3.2. Kinase inhibition
The docking analysis indicated that compound 6i fit into the 277
binding site of VEGFR and PI3K kinases suggesting that this 278
Compounds 5n, 6f, 6i and 6j were selected for further
evaluation in VEGFR2 and PI3K
a
kinases inhibition assays at the
compound may be a potent VEGFR and PI3K inhibitor.
279
concentration of 20 mol/L with Staurosporine and PI103 as
m
controls, respectively. As the kinase assay results reveal in Table 3
compound 5n showed no obvious kinase inhibition against both
VEGFR2 and PI3K kinases. Compound 6f showed selective kinases
inhibition with lower for VEGFR2 (7.03%) but better against PI3K
(38.77%). Furthermore, compounds 6f, 6i and 6j exhibit moderate
4. Conclusion
280
In summary, a series of novel compounds possessing a 2- 281
aminothiazole scaffold were prepared. Most of the modified 282
compounds showed tantamount or better cytotoxicity against 283
either HepG2 or MDA-MB-231 cell lines. Compounds 6h–6l 284
showed higher and better potency against the two cancer cell 285
lines than Sorafenib. SARs studies indicated that a benzene ring 286
and thiazole ring linked by urea, and as well as removal of the 287
methane group, are crucial for the antitumor activity. The 288
molecular docking studies and the results of kinase inhibition 289
assay in vitro suggest that compound 6i may be a potent VEGFR-2 290
a
inhibitory activities against VEGFR2 kinase within the range of 26–
36% and good PI3K
result is consistent with cell cytotoxicity activity. Our findings
suggest that compounds 6i and 6j exhibit good PI3K inhibitory
a inhibitory activity in the range of 38–58%. This
a
activity and moderate VEGFR-2 inhibitory activities, while
Table 3
and PI3Ka dual inhibitor. The 2-aminothiazole scaffold may be 291
Inhibitory activity of compounds selected with two kinases (inhibitory rate, %) at
20 mmol/L.
considered a promising structure for future designs of VEGFR-2 292
and PI3K
a
dual inhibitors.
Q4293
Compound
VEGFR2 (%)
PI3Ka (%)
5n
8.82
7.03
36.58
26.95
99.71
–
2.03
38.77
58.44
54.26
–
Acknowledgments
294
6f
6i
6j
The authors would like to thank the financial supports from the 295
NSFC (No. 21272134) and Shenzhen Municipal government SZSITIC Q5296
(Nos. JCYJ20130402145002384, ZDSY20120619141412872).
Staurosporine
PI103
99.94
297
Please cite this article in press as: L. Li, et al., Discovery of novel dual inhibitors of VEGFR and PI3K kinases containing 2-ureidothiazole
scaffold, Chin. Chem. Lett. (2015), http://dx.doi.org/10.1016/j.cclet.2015.09.008

G Model
CCLET 3431 1–6
6
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[10] G.R. Gao, J.L. Liu, D.S. Mei, et al., Design, synthesis and biological evaluation of
324
325
326
327
328
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330
331
332
333
334
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Appendix A. Supplementary data
acylhydrazone derivatives as PI3K inhibitors, Chin. Chem. Lett. 26 (2015) 118–
120.
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300
301
Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.cclet.2015.09.
008.
[11] S. Brader, S.A. Eccles, Phosphoinositide 3-kinase signalling pathways in tumor
progression, invasion and angiogenesis, Tumori 90 (2004) 2–8.
[12] X.H. Ma, R. Wang, C.Y. Tan, et al., Virtual screening of selective multitarget kinase
inhibitors by combinatorial support vector machines, Mol. Pharm. 7 (2010) 1545–
1560.
[13] L.Y. Han, X.H. Ma, H.H. Lin, et al., A support vector machines approach for virtual
screening of active compounds of single and multiple mechanisms from large
libraries at an improved hit-rate and enrichment factor, J. Mol. Graph. Model. 26
(2008) 1276–1286.
[14] D.M. Zhao, W.Y. Li, Y.F. Shi, et al., Pharmacophore-based design, synthesis, and
biological evaluation of novel 3-((3,4-dichlorophenyl)(4-substituted benzyl)ami-
no)propanamides as cholesteryl ester transfer protein (CETP) inhibitors, Chin.
Chem. Lett. 25 (2010) 299–304.
[15] F. Palagiano, L. Arenare, E. Luraschi, et al., ChemInform abstract: research on
heterocyclic compounds, Part 34. Synthesis and SAR study of some imidazo (2,1-
b)thiazole carboxylic and acetic acids with antiinflammatory and analgesic
activities, ChemInform 27 (1996).
[16] A.J. King, A.S. Judd, A.J. Souers, Inhibitors of Diacylglycerol Acyltransferase: a
review of 2008 patents, Expert. Opin. Ther. Pat. 20 (2010) 19–29.
[17] D.M. Swanson, C.R. Shah, B. Lord, et al., Heterocyclic replacement of the central
phenyl core of diamine-based histamine H3 receptor antagonists, Eur. J. Med.
Chem. 44 (2009) 4413–4425.
[18] M.H. Potashman, J. Bready, A. Coxon, et al., Design, synthesis, and evaluation of
orally active benzimidazoles and benzoxazoles as vascular endothelial growth
factor-2 receptor tyrosine kinase inhibitors, J. Med. Chem. 50 (2007) 4351–
4373.
302
References
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
[1] M. Abdelrahim, S. Konduri, R. Basha, et al., Angiogenesis: an update and potential
drug approaches (review), Int. J. Oncol. 36 (2010) 5–18.
[2] P. Bhargava, M.O. Robinson, Development of second-generation VEGFR tyrosine
kinase inhibitors: current status, Curr. Oncol. Rep. 13 (2011) 103–111.
[3] P. Carmeliet, R.K. Jain, Angiogenesis in cancer and other diseases, Nature 407
(2000) 249–257.
[4] K.M. Cook, W.D. Figg, Angiogenesis inhibitors: current strategies and future
prospects, CA-Cancer J. Clin. 60 (2010) 222–243.
[5] P.S. Sharma, R. Sharma, T. Tyagi, VEGF/VEGFR pathway inhibitors as anti-angio-
genic agents: present and future, Curr. Cancer Drug Targets 11 (2011) 624–653.
[6] J.A. Engelman, J. Luo, L.C. Cantley, The evolution of phosphatidylinositol 3-kinases
as regulators of growth and metabolism, Nat. Rev. Genet. 7 (2006) 606–619.
[7] M.T. Burger, S. Pecchi, A. Wagman, et al., Identification of NVP-BKM120 as a
potent, selective, orally bioavailable class I PI3 Kinase inhibitor for treating cancer,
ACS Med. Chem. Lett. 2 (2011) 774–779.
[8] Y.W. Zhao, L. Jin, Z.M. Li, et al., Enhanced antitumor efficacy by blocking activation
of the phosphatidylinositol 3-kinase/Akt pathway during anti-angiogenesis ther-
apy, Cancer Sci. 102 (2011) 1469–1475.
[9] G.D. Thakker, D.P. Hajjar, W.A. Muller, et al., The role of phosphatidylinositol 3-
kinase in vascular endothelial growth factor signaling, J. Biol. Chem. 274 (1999)
10002–10007.
[19] S.D. Knight, N.D. Adams, J.L. Burgess, et al., Discovery of GSK2126458, a highly
potent inhibitor of PI3K and the mammalian target of rapamycin, ACS Med. Chem.
Lett. 1 (2010) 39–43.
Please cite this article in press as: L. Li, et al., Discovery of novel dual inhibitors of VEGFR and PI3K kinases containing 2-ureidothiazole
scaffold, Chin. Chem. Lett. (2015), http://dx.doi.org/10.1016/j.cclet.2015.09.008