Aminoquinoline derivatives with antiproliferative activity against melanoma cell line

Article abstract of DOI:10.1016/j.bmcl.2009.05.007

The synthesis of a novel series of aminoquinoline derivatives 1a-p and their antiproliferative activities against A375 human melanoma cell line were described. Most compounds showed superior antiproliferative activities to Sorafenib as a reference compoun

Full text of DOI:10.1016/j.bmcl.2009.05.007

Bioorganic & Medicinal Chemistry Letters 19 (2009) 3517–3520
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Aminoquinoline derivatives with antiproliferative activity against
melanoma cell line
Bong Soo Nam a,b, Hwan Kim a, Chang-Hyun Oh a, So Ha Lee a, Seung Joo Cho c,d, Tae Bo Sim a, Jung-Mi Hah a,
Dong Jin Kim a, Jung Hoon Choi b, Kyung Ho Yoo a,
*
a Life Sciences Research Division, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-650, Republic of Korea
b Department of Chemistry, Hanyang University, Seoul 133-791, Republic of Korea
c Research Center for Resistant Cells, Chosun University, Gwangju 501-759, Republic of Korea
d Department of Cellular and Molecular Medicine, College of Medicine, Chosun University, 375 Seosuk-dong, Dong-gu Gwangju 501-759, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of a novel series of aminoquinoline derivatives 1a–p and their antiproliferative activities
against A375 human melanoma cell line were described. Most compounds showed superior antiprolifer-
ative activities to Sorafenib as a reference compound. Among them, quinolinyloxymethylphenyl com-
pounds 1k and 1l exhibited potent activities (IC50 = 0.77 and 0.79 lM, respectively) and excellent
selectivity against melanoma and fibroblast cell lines.
Received 13 March 2009
Revised 1 May 2009
Accepted 2 May 2009
Available online 7 May 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Aminoquinolines
Antiproliferative activity
Melanoma cell line
Fibroblast cell line
Selectivity
Melanoma is the most serious type of skin cancer as a malignant
tumor of melanocytes. Incidence of melanoma has tripled in the
last 40 years, and more than 80% of skin cancer deaths are due mel-
anoma. Generally, two major risk factors for melanoma develop-
ment are an individual’s family history and an environmental
factor. The most relevant environmental factor is exposure to solar
ultraviolet irradiation that causes damage to the DNA of cells.1
In early-stage melanoma without metastasis, treatment for
localized melanoma normally involves surgery to remove the le-
sion. If it is not detected early, melanomas can grow down into
the skin and spread to other parts of the body either by the lym-
phatic or by the hematogenous route.2 Metastatic melanoma can
be fatal with the 5-year survival rate below 15% and median sur-
vival of about 6–8 months.3–6
The current treatment involves surgical removal of the tumor,
immunotherapy, radiotherapy, chemotherapy, various combina-
tions or use of new treatments in clinical trials. As for immunother-
apy, interferon alfa-2b (Intron-A)7 is approved by both the FDA and
EMEA for adjuvant treatment of melanoma patients, and aldesleu-
kin (Proleukin)8,9 is also approved for the treatment of metastatic
melanoma in US.
Temozolomide (Temodar)10 or decarbazine (DTIC)11,12 as a che-
motherapy are used most frequently for stage IV melanoma pa-
tients. Decarbazine is the only cytotoxic formally approved for
the treatment of melanoma and Temodar is currently in preregis-
tration. However, due to the development of metastatic disease
which is highly resistant to conventional chemotherapeutics and
radiation,13 the intensive research and effort into new drugs and
treatments14–19 afforded merely the response rates of approxi-
mately 20% or less.
Based on the structural features of Sorafenib (Nexavar)20 that
has been used extensively in clinical trials, an aminoquinoline scaf-
fold for b-Raf kinase inhibitors was designed as shown in Figure 1.
We report here the synthesis of a novel series of aminoquinoline
derivatives 1a–p and their antiproliferative activities and selectiv-
ities against human melanoma cell line and fibroblast cell line.
H
N
H
N
CF3
Cl
R3
O
H
N
N
N
R2
H
N
O
R1
O
O
O
1a-p
Sorafenib
R1 = NH2, CH3CONH
R
R
2 = ArNH, Ar, HeteroAr
3 = H, CH3
* Corresponding author. Tel.: +82 2 958 5152; fax: +82 2 958 5189.
E-mail address: khyoo@kist.re.kr (K.H. Yoo).
Figure 1. Structures of Sorafenib and aminoquinoline derivatives.
0960-894X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2009.05.007

3518
B. S. Nam et al. / Bioorg. Med. Chem. Lett. 19 (2009) 3517–3520
OCN
CF3
Cl
NH2
N
N
N
NH2
i
HO
O2N
O2N
O
Cl
Cl
ii
iii
4
2
3
H
N
H
N
H
N
H
N
N
N
CH3CO2H
v
CF3
Cl
CF3
Cl
iv
O2N
H2N
O
O
O
O
5
1a,c
H
N
H
N
H
N
N
CF3
Cl
O
O
O
1b,d
Scheme 1. Reagents and reaction conditions: (i) HNO3, H2SO4, 0 °C to rt, 4 h, 56%; (ii) tBuOK, DMF, 110 °C, 7 h, 59% (p-Ph), 23% (m-Ph); iii) THF, rt, 12 h, 89% (p-Ph), 54% (m-
Ph); (iv) SnCl2, EtOH, reflux, 30 min, 75% (1a), 85% (1c); (v) HOBt, EDCI, TEA, DMF, 80 °C, 12 h, 81% (1b), 31% (1d).
Quinolinyloxyphenyl derivatives 1a–d with urea moiety at the
terminal part were prepared by the sequence of reactions shown
in Scheme 1. 4-Chloroquinoline (2) with nitric acid in the presence
of sulfuric acid gave 4-chloro-8-nitroquinoline (3),21 which was
then coupled with aminophenols to give quinolinyloxy compounds
4 as key intermediates.22 The title compounds 1a,c were obtained
by treatment of 4 with phenylisocyanate,23 and subsequent reduc-
tion of nitro group of the resulting ureas 5 using stannous chloride,
respectively.24 Acetylation of 1a,c using HOBt and EDCI provided
the corresponding title compounds 1b,d, respectively.25
The synthesis of 1f,h with amide moiety at the terminal part
was outlined in Scheme 2. Amide coupling of 4 with 4-chloro-3-tri-
fluoromethylbenzoic acid using HOBt and EDCI followed by reduc-
tion of 6 led to the title compounds 1e,g, respectively. Acetylation
of 1e,g was carried out by using procedures analogous to those de-
scribed above to provide 1f,h.
Quinolinyloxymethylphenyl compounds 1i–p having an addi-
tional methyl group to afford the restricted conformation were
prepared in several steps using nitroquinoline 3 as a starting mate-
rial (Scheme 3). Coupling of 3 with Boc-protected methylami-
nophenol by potassium t-butoxide gave nitroquinolinyloxy
compound 7, and subsequent reduction of 7 with Pd/C afforded
amino compound 8. Acetylation of 8 followed by deprotection with
trifluoroacetic acid gave the compound 10, which was reacted with
the appropriate carboxylic acids to give the corresponding title
compounds 1i–p, respectively.
Table 1 shows the antiproliferative activities26 (IC50 values) of
quinolinyloxyphenyl derivatives 1a–h against A375 human mela-
noma cell line and HS27 fibroblast cell line together with that of
Sorafenib as a reference compound.
Most compounds showed better antiproliferative activity
against A375 human melanoma cell line than Sorafenib. In gen-
HO2C
CF3
Cl
Cl
Cl
H
N
H
N
N
N
ii
O2N
H2N
CF3
CF3
O
O
4
O
O
i
6
1e,g
Cl
CF3
H
N
N
H
CH3CO2H
iii
N
O
O
O
1f,h
Scheme 2. Reagents and reaction conditions: (i) HOBT, EDCI, TEA, DMF, 80 °C, 12 h, 71% (p-Ph), 97% (m-Ph); (ii) SnCl2, EtOH, reflux, 30 min, 26% (1e), 65% (1g); (iii) HOBt,
EDCI, TEA, DMF, 80 °C, 12 h, 41% (1f), 31% (1h).
N
N
CH3CO2H
iii
ii
HO
NHBoc
H2N
O2N
O
NHBoc
3
O
NHBoc
i
8
7
N
N
O
N
H
N
H
H
R-CO2H
v
iv
N
N
O
NHBoc
O
N
H
R
O
NH2
O
O
O
9
1i-p
10
Scheme 3. Reagents and reaction conditions: (i) tBuOK, DMF, 110 °C, 7 h, 68%; (ii) 5% Pd/C, H2, MeOH, rt, 3 h, 73%; (iii) HOBt, EDCI, TEA, DMF, 80 °C, 12 h, 82%; (iv) CH2Cl2/TFA
(1:1) solution, rt, 1 h, 89%; (v) acid, HOBt, EDCI, TEA, DMF, 80 °C, 12 h, 26–91% (1i–p).

B. S. Nam et al. / Bioorg. Med. Chem. Lett. 19 (2009) 3517–3520
3519
Table 1
eral, urea compounds 1a–d possessed slightly potent activities as
compared to amide compounds 1e–h. Positional effect according
to p- or m-orientation of middle benzene ring did not make any
significant difference of activity. Acetylamino compound 1h with
m-orientation displayed very good selectivity against HS27 fibro-
blast cell line as a control in addition to high potency against
melanoma cell line. However, conversion of the amino group to
acetylamino group on the quinoline nucleus did not show a
meaningful trend.
Shown in Table 2, some of quinolinyloxymethylphenyl deriva-
tives 1i–p with acetylamino and m-oriented structure showed
superior antiproliferative activities to Sorafenib. Furthermore, they
possessed excellent selectivity against melanoma compared to
fibroblast cell lines. In particular, compounds 1k and 1l having
electron-withdrawing groups on the terminal benzene nucleus
Antiproliferative activity of quinolinyloxyphenyl derivatives 1a–h
Cl
H
N
H
N
H
N
N
N
CF3
Cl
R
R
CF3
O
O
O
O
1a-d
1e-h
Compd
Orientation
R
IC50
(
l
M)
A375
HS27
1a
1b
1c
1d
1e
1f
1g
1h
Sorafenib
p-Phenyl
p-Phenyl
m-Phenyl
m-Phenyl
p-Phenyl
p-Phenyl
m-Phenyl
m-Phenyl
NH2
CH3CONH
NH2
CH3CONH
NH2
CH3CONH
NH2
3.74 0.16
4.19 2.13
2.56 0.09
2.32 0.54
5.69 0.13
3.14 0.36
6.73 0.24
3.49 0.35
5.58
6.71 1.62
6.02 0.29
10.39 1.91
5.68 0.18
7.63 1.01
5.47 0.74
>20
exhibited excellent antiproliferative activities (0.77 and 0.79
respectively) with IC50 values in the nanomolar range.
lM,
CH3CONH
>20
7.85
The representative compound 1k was screened against V600E-
b-Raf enzyme in vitro using cascade assay system. However, com-
pound 1k did not show a meaningful b-Raf inhibitory activity.
Accordingly, the selectivity profile of 1k was assessed against a pa-
nel of 30 protein kinases at a single concentration of 10 lM to find
kinase target. This compound exhibited good selectivity profile for
c-Raf and Abl inhibition with significant activity over other kinases
tested. Verification of mode of action is under way.
In conclusion, a series of aminoquinoline derivatives based on
the structural features of Sorafenib showed potent antiproliferative
activities against A375 human melanoma cell line. In our series,
quinolinyloxymethylphenyl compounds 1k and 1l exhibited both
potent activity and excellent selectivity compared to Sorafenib.
These results suggest that aminoquinoline derivatives have poten-
tials as a therapeutic agent for treatment of melanoma.
Table 2
Antiproliferative activity of quinolinyloxymethylphenyl derivatives 1i–p
N
O
H
N
O
N
H
R
O
1i-p
Compds
1i
R
IC50 (lM)
A375
HS27
>20
CF3
Cl
1.30 0.08
1.28 0.19
0.77 0.07
0.79 0.02
Acknowledgments
We are grateful to the Korea Institute of Science and Technology
(KIST) for financial support.
CF3
CF3
1j
>20
>20
>20
References and notes
1k27
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for 24 h in a humidified atmosphere with 5% CO2 prior to treatment of various
concentration (threefold serial dilution, 12 points) of test compounds. The
A357P cell viability was assessed by the conventional 3-(4,5-dimethylthiazol-
2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay. MTT assays
were carried out with CellTiter 96Ò (Promega) according to the manufacturer’s
instructions. The absorbance at 590 nm was recorded using EnVision 2103
(Perkin Elmer; Boston, MA, US). The IC50 was calculated using GraphPad Prism
4.0 software.
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26. A375P cells were purchased from American Type Culture Collection (ATCC,
Rockville, MD, US) and maintained in DMEM medium (Welgene, Daegu, Korea)
supplemented with 10% FBS (Welgene) and 1% penicillin/streptomycin
(Welgene) in a humidified atmosphere with 5% CO2 at 37 °C. A375P cells
were taken from culture substrate with 0.05% trypsin–0.02% EDTA and plated
at a density of 5 Â 103 cells/well in 96 well plates and then incubated at 37 °C
27. Selected data. Compound 1k: 1H NMR (400 MHz, DMSO-d6) d 2.14 (s, 1H), 2.28
(s, 1H), 6.65 (d, J = 5.08 Hz, 1H), 7.47 (d, J = 8.81 Hz, 1H), 7.61–7.70 (m, 3H),
8.02 (d, J = 8.78 Hz, 1H), 8.37 (s, 1H), 8.58 (s, 2H), 8.68 (d, J = 7.76 Hz, 1H), 8.72
(d, J = 5.09 Hz, 1H), 10.12 (s, 1H), 10.76 (s, 1H); 13C NMR (100 MHz, DMSO-d6) d
15.47, 25.00, 105.04, 113.67, 115.45, 117.87, 118.58, 120.79, 121.74, 125.36,
126.01, 127.30, 128.98, 130.30, 130.74, 131.19, 131.63, 132.44, 135.27, 137.33,
138.59, 140.14, 150.28, 152.09, 161.10, 163.02, 169.44; MS m/z 548 (M+H)+.
Compound 1l: 1H NMR (400 MHz, DMSO-d6) d 2.12 (s, 3H), 2.26 (s, 3H), 6.62 (d,
J = 5.12 Hz, 1H), 7.44 (d, J = 8.34 Hz, 1H), 7.59–7.69 (m, 4H), 8.00 (d, J = 8.33 Hz,
1H), 8.30 (d, J = 8.20 Hz, 1H), 8.42 (d, J = 8.45 Hz, 1H), 8.47 (s, 1H), 8.67 (d,
J = 7.66 Hz, 1H), 8.70 (d, J = 5.14 Hz, 1H), 10.10 (s, 1H), 10.76 (s, 1H); 13C NMR
(100 MHz, DMSO-d6) d 15.43, 24.94, 104.98, 113.57, 115.52, 117.93, 118.53,
120.76, 121.64, 122.08, 124.12, 126.13, 126.18, 127.28, 127.68, 132.46, 134.25,
135.16, 138.483, 139.12, 140.111, 149.12, 150.30, 152.04; MS m/z 525 (M+H)+.