Microwave-promoted facile access to 4-aminoquinoline-phthalimides: Synthesis and anti-plasmodial evaluation

Article abstract of DOI:10.1016/j.ejmech.2017.11.033

Microwave promoted high yielding synthesis of 4-aminoquinoline-phthalimides was developed with an aim to evaluate their anti-plasmodial potential. The scaffolds with longer spacer length (n = 6, 8) between two pharmacophores and a halogen substituent on the phthalimide ring displayed good antiplasmodial activity. Compound 5w, with an optimum combination of hexyl chain as spacer along with a tetra-bromophthalimide ring proved to be most potent and non-cytotoxic among the series exhibiting an IC₅₀ value of 0.10 μM.

Full text of DOI:10.1016/j.ejmech.2017.11.033

European Journal of Medicinal Chemistry 143 (2018) 150e156
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Microwave-promoted facile access to 4-aminoquinoline-
phthalimides: Synthesis and anti-plasmodial evaluation
,
*
Anu Rani a, Amandeep Singh a, Jiri Gut b, Philip J. Rosenthal b, Vipan Kumar a
a Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, Punjab, India
b Department of Medicine, University of California, San Francisco, CA, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Microwave promoted high yielding synthesis of 4-aminoquinoline-phthalimides was developed with an
aim to evaluate their anti-plasmodial potential. The scaffolds with longer spacer length (n ¼ 6, 8) be-
tween two pharmacophores and a halogen substituent on the phthalimide ring displayed good anti-
plasmodial activity. Compound 5w, with an optimum combination of hexyl chain as spacer along with a
tetra-bromophthalimide ring proved to be most potent and non-cytotoxic among the series exhibiting an
Received 25 July 2017
Received in revised form
9 November 2017
Accepted 13 November 2017
Available online 16 November 2017
IC50 value of 0.10 mM.
© 2017 Elsevier Masson SAS. All rights reserved.
Keywords:
4-aminoquinoline-phthalimides
Microwave synthesis
Anti-plasmodial evaluation
Cytotoxicity
Selectivity index
1. Introduction
pharmacological templates with a potential to enhance antima-
larial efficacy and be cost-effective [5e8]. Several potential anti-
malarials viz. trioxoferroquines [5], trioxaquines [9], artemisinin-
quinine [10], tetraoxanes [11] and clotrimazole-4-aminoquinoline
[12] have been developed using this strategy.
Malaria caused by Plasmodium falciparum, is a rapidly spreading
parasitic disease responsible for 214 million cases worldwide in
2015 along with 438,000 deaths mostly in sub-Saharan African
region [1]. Chloroquine was the most accessible, effective and safe
drug for the treatment of falciparum malaria for at least five de-
cades and is still considered as a drug of choice against uncompli-
cated malaria caused by P. vivax [2]. The emergence of drug
resistant parasites and the lack of an effective malaria vaccine are
the major obstacles in the control and eventual elimination of the
disease. The development of resistance to the quinoline antima-
larials has propelled the development of artemisinin (ART) and its
semisynthetic derivatives as fast-acting antimalarials [3]. However,
recent reports on the emergence of resistance to artemisin com-
bination therapy (ACT) in South-East Asia has provided strong
impetus for the development of new antimalarial scaffolds with
low incidence of resistance [4].
Derivatives of cyclic imide having the general structure
e(COeN(R)-CO)- are an important class of bioactive molecules
showing numerous biological properties including antimicrobial,
antimalarial, antihypertensive, antiviral and herbicidal activities
[13]. Rathi et al. recently reported a series of phthalimides func-
tionalized with cyclic amines and evaluated for their in vitro anti-
malarial activities against the 3D7 strain of P. falciparum as well as
for falcipain-2 (FP2) inhibitory activity. The combination of the
most potent compound with ART resulted in enhanced killing of
P. falciparum. Phthalimides and their derivatives, thus emerged as
potential candidates, which can be used in combination with ARTor
with other antimalarials to reduce the problem of drug resistance
[14].
4-aminoquinoline hybridization, involving re-engineering and
repositioning of the quinoline core with known drug families, has
emerged as an important strategy for the development of new
Recent disclosures from our lab have shown the antiplasmodial
potential of amalgamating a 4-aminoquinoline with a
b-lactam
(cyclic amide) core tethered via diverse linkers. The synthesized
conjugates have shown comparable antiplasmodial activity to that
of chloroquine with IC50 values of the most potent conjugates being
35 nM and 42 nM [15]. In continuation with our interest in the
synthesis and bio-evaluation of new molecular scaffolds with
* Corresponding author.
E-mail address: vipan_org@yahoo.com (V. Kumar).
https://doi.org/10.1016/j.ejmech.2017.11.033
0223-5234/© 2017 Elsevier Masson SAS. All rights reserved.

A. Rani et al. / European Journal of Medicinal Chemistry 143 (2018) 150e156
151
biological relevance [16], the present report describes the synthe-
sis, antiplasmodial and cytotoxic evaluation of 4-aminoquinoline-
phthalimides. The length of the linker as well as the nature of
substituents at the C3/C4 position of phthalimide was varied so as
to study the structure-activity relationship (SAR) of synthesized
scaffolds.
of absorptions at d 168.5 corresponding to phthalimide carbonyls
along with the appearance of methylene carbons at d 36.3 and 40.6
as confirmed by 13C NMR (DEPT) spectra further substantiated the
assigned structure (see Scheme 3).
The synthesized 4-aminoquinoline-phthalimides were evalu-
ated for their antiplasmodial activity against the chloroquine (CQ)-
resistant and mefloquine-sensitive W2 strain of P. falciparum and
the activities are listed in Table 2. As evident, although the scaffolds
are not as active as standard drugs viz. CQ and ART; most of the
compounds displayed good antiplasmodial activity. A careful
analysis of structure-activity relationship (SAR) of the synthesized
compounds revealed the dependence of activity both on the nature
of substituents at the phthalimide ring as well as the alkyl chain
length, introduced as spacer. Analysis of antiplasmodial activities
among compounds 5a-e (R ¼ H) revealed an improvement in ac-
tivity with increase in chain length as evident from compounds 5d
2. Results and discussion
The synthetic methodology involved an initial treatment of
precursor 3a, prepared by reacting 4,7-dichloroquinoline 1 with
ethylene diamine [17] (Scheme 1), with phthalic anhydride 4a. The
reaction was carried out in a range of solvents at varied tempera-
ture and resulted in poor to moderate yields of the corresponding
4-aminoquinoline-phthalimide 5a. The best results in terms of
yields were obtained by heating in acetic acid at 110 ꢀC for 6h. In
order to circumvent the poor yields observed in the conventional
heating, it was considered worthwhile to attempt the microwave-
promoted synthesis of 4-aminoquinoline-phthalimides. Micro-
wave heating has emerged as a powerful tool for the synthesis of
various heterocycles and a number of publications have appeared
lately describing its potential in phthalimide synthesis [18]. The
reaction between phthalic anhydride 4a and 4-aminoquinoline-
diamine 3a was chosen as a model reaction for optimizing reaction
conditions. A range of solvents under different temperatures and
time were screened so as to optimize the reaction conditions. The
choice of solvent proved to be crucial on the reaction outcome and
the best result in terms of yield was obtained using 0.5 mL of DMSO
at 160 ꢀC for 2 min (see Table 1) (Scheme 2). Having determined
suitable reaction conditions, the developed strategy was next
(n ¼ 6, 0.11
mM) and 5e (n ¼ 8, 0.14
mM). Introducing a fluoro or
nitro substituent at C-3, C-4 position resulted in the reduction of
antiplasmodial efficacy at shorter alkyl chain lengths (ethyl and
propyl) while the activity improved considerably at longer alkyl
chain lengths as evident by 5i, 5j, 5n, 5o and 5y. Introducing a
tetrabromo and tetrachloro-phthalimide substantially improved
the activity profiles even at shorter alkyl chain lengths. The com-
pounds 5n, 5w and 5y with an optimum combination of hexyl chain
length as linker and halogen substituents on the phthalimide ring
proved to be most potent among the series, exhibiting IC50 values of
0.12, 0.10 and 0.15 mM, respectively.
Cytotoxicity of the potent scaffolds viz. 5d, 5j, 5n and 5w was
determined using J774 murine macrophage cells in order to
ascertain whether the observed activities are due to their anti-
plasmodial efficacy or cytotoxicity (Table 3). As evident, the com-
pounds were non-cytotoxic to J774 murine macrophage cells and
their Selectivity index ranges from 126 to 291.
In conclusion, a high yielding microwave-promoted synthesis of
4-aminoquinoline-phthalimides was developed with the aim of
studying SAR against P. falciparum. Most of the synthesized scaf-
folds were non-cytotoxic and displayed good antiplasmodial pro-
files with the activities being dependent upon the nature of
substituent on the phthalimide ring as well as the length of alkyl
chain, introduced as spacer. Higher values of selectivity index of
most potent compounds among the series is suggestive of the fact
explored with
a variety of phthalimide substrates and 4-
aminoquinolines affording facile synthesis of a library of 4-
aminoquinoline-phthalimides 5a-y in excellent yields. The struc-
ture of the synthesized scaffolds was assigned on the basis of
spectral data and analytical evidences. The compound 5a, for
example, analyzed as C19H14ClN3O2, showed a molecular ion peak
at m/z 351.0781 [M]þ in its high resolution mass spectrum. The
salient features of its 1H NMR spectrum included the appearance of
a multiplet at
sponding to methylene protons and a multiplet at
because of aromatic protons of the phthalimide ring. The presence
d
3.52e3.57 and a triplet at 3.78 (J ¼ 6.2 Hz) corre-
d
7.77e7.82,
Scheme 1. Synthesis of 4-aminoquinoline based diamines.
Table 1
Synthesis of 4-aminoquinoline-phthalimide 5a, both under conventional and microwave heating.
Conventional heating
Solvent
Microwave heating
Time
Temperature
% yield
Solvent
Time
Temperature
% yield
CH3CN
DMF
DMSO
C2H5OH
CH3COOH
6h
6h
8h
6h
6h
80
22%
31%
51%
34%
50%
CH3CN
DMF
DMSO
CH3COOH
3min
5min
2min
5min
80
39%
81%
89%
76%
130
160
80
130
160
110
110

152
A. Rani et al. / European Journal of Medicinal Chemistry 143 (2018) 150e156
Scheme 2. Synthesis of 4-aminoquinoline-phthalimide 5a.
Scheme 3. Microwave promoted synthesis of 4-aminoquinoline-phthalimides (5b-5y).
that these compounds can act as starting points for the synthesis of
3.1. General procedure for synthesis of 4-aminoquinoline-
new pharmacological templates against P. falciparum.
phthalimide 5a under conventional heating
To a stirred solution of phthalic anhydride 4a (1.0 eq.) in 5 mL of
acetic acid was added 4-aminoquinoline diamine 3a (1.0 eq.). The
reaction mixture was refluxed for 6h at 110 ꢀC and the progress was
monitored by TLC. The crude product was poured in water (20 mL)
and extracted with ethyl acetate (2 ꢁ 20 mL). The combined organic
layers were dried over anhydrous Na2SO4 and concentrated under
reduced pressure. Pure product was obtained by re-crystallisation
using absolute ethanol.
3. Experimental section
Melting points were determined by open capillary using a
Veego Precision Digital Melting Point apparatus (MP-D) and are
uncorrected. 1H NMR spectra were recorded in DMSO-d6 with
Bruker 500 (500 MHz) spectrometers using TMS as internal
standard. Microwave reactions were carried out in a Biotage®
Initiator þ instrument using sealed 2e5 mL process vials. Reaction
times refer to irradiation time at the target temperature, not the
total irradiation time. The temperature was measured with an IR
sensor. Chemical shift values are expressed as parts per million
downfield from TMS, and J values are in hertz. Splitting patterns
are indicated as s: singlet, d: doublet, t: triplet, m: multiplet, dd:
double doublet, ddd: doublet of a doublet of a doublet, and br:
broad peak. 13C NMR spectra were recorded on Bruker 500 MHz
spectrometers in DMSO-d6 using TMS as internal standard. High
resolution mass spectra were recorded on a Bruker-micrOTOF-Q II
spectrometer.
3.2. General procedure for microwave promoted synthesis of 4-
aminoquinoline-phthalimides (5a-5y)
To substituted phthalic anhydride (1.0 eq.) in 0.5 mL of DMSO
was added 4-aminoquinoline based diamines (1.0 eq.) in a micro-
wave reaction vial. The vessel was sealed with a PTFE cap and
heated to 160ꢀ C for 2 min in a microwave reactor. After completion
of the reaction as evident from TLC, the vessel contents were
poured in water (20 mL) and extracted with ethyl acetate
(2 ꢁ 30 mL). The organic layers were combined, dried over

A. Rani et al. / European Journal of Medicinal Chemistry 143 (2018) 150e156
153
Table 2
379.1088. Found 379.1091.
Antiplasmodial activities of tested compounds against the CQ-resistant W2 strain of
P. falciparum.
3.2.4. 2-(6-(7-chloroquinolin-4-ylamino)hexyl)isoindoline-1,3-
Compound
IC50
(
m
M) SD
Compound
IC50 (mM) SD
dione (5d)
Light yellow solid, M.P ¼ 109-110 OC 1H NMR (DMSO-d6,
400 MHz): 1.25e1.40 (m, 4H, 2CH2), 1.52e1.64 (m, 4H, 2CH2),
3.43e3.48 (m, 2H, CH2), 3.52 (t, J ¼ 7.0 Hz, 2H, CH2), 6.80 (d,
J ¼ 7.1 Hz, 1H, H2), 7.70 (dd, J ¼ 9.0 Hz, 1.2 Hz, 1H, H4), 7.76e7.81 (m,
4H, Ar-H), 8.01 (d, J ¼ 1.7 Hz,1H, H5), 8.46 (d, J ¼ 7.1 Hz,1H, H1), 8.60
(d, J ¼ 9.1 Hz, 1H, H3) 9.49 (t, J ¼ 4.7 Hz, 1H, NH-exchangeable with
D2O). 13C NMR (DMSO-d6, 100 MHz): 26.4, 26.5, 27.9, 28.3, 37.8,
43.5, 99.0, 115.9, 119.4, 123.4, 126.3, 127.2, 132.0, 134.9, 138.3, 139.0,
143.0, 155.7, 168.4. C23H22ClN3O2 [M]þ 407.1401. Found 407.1412.
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
1.11 0.01
1.51 0.02
0.37 0.05
0.11 0.004
0.14 0.01
4.73 0.8
3.96 0.17
0.64 0.11
0.24 0.01
0.12 0.0001
4.56 0.46
1.19 0.16
0.42 0.01
0.12 0.07
5o
5p
5q
5r
5s
5t
5u
5v
5w
5x
5y
CQ
ART
0.17 0.007
0.21 0.05
0.57 0.04
0.27 0.000002
0.46 0.00003
0.40 0.03
3.76 0.02
0.19 0.03
0.10 0.006
7.55 0.30
0.15 0.02
0.077 0.004
0.007 0.0007
3.2.5. 2-(8-(7-chloroquinolin-4-ylamino)octyl)isoindoline-1,3-
dione (5e)
Yellow Semisolid Liquid, 1H NMR (DMSO-d6, 500 MHz):
1.23e1.38 (m, 8H, 4CH2), 1.55e1.66 (m, 4H, 2CH2), 3.27e3.29 (m,
2H, CH2), 3.56 (t, J ¼ 5.7 Hz, 2H, CH2), 6.52 (d, J ¼ 5.8 Hz, 1H, H2),
7.49 (dd, J ¼ 8.9 Hz, 2.2 Hz, 1H, H4), 7.63 (t, J ¼ 6.0 Hz, 1H, NH-
exchangeable with D2O), 7.79 (d, J ¼ 2.2 Hz, 1H, H5), 7.79e7.88
(m, 4H, Ar-H), 8.31 (d, J ¼ 9.0 Hz, 1H, H3), 8.40 (d, J ¼ 5.6 Hz, 1H, H1).
13C NMR (DMSO-d6, 125 MHz): 26.7, 26.9, 28.1, 28.3, 29.0, 29.5, 37.8,
43.3, 99.0, 116.9, 123.5, 123.6, 125.8, 132.0, 134.9, 136.1, 144.3, 147.8,
153.2, 168.4. C25H26ClN3O2 [M]þ 435.1714. Found 435.1721.
Table 3
Cytotoxicity of selected compounds on J774 murine macrophage cells and their
Selectivity index.
Compound
IC50
(
mM)
Cytotoxicity (
m
M)
Selectivity Index (SI)
5d
5j
5n
5w
0.11
0.12
0.12
0.10
14.34
28.24
15.16
29.11
130.36
235.33
126.33
291.1
3.2.6. 2-(2-(7-chloroquinolin-4-ylamino)ethyl)-4-
fluoroisoindoline-1,3-dione (5f)
Light yellow solid, M.P ¼ 160-161 OC 1H NMR (DMSO-d6,
500 MHz): 3.57e3.61 (m, 2H, CH2), 3.80 (t, J ¼ 6.2 Hz, 2H, CH2), 6.64
(d, J ¼ 5.4Hz, 1H, H2), 7.43 (dd, J ¼ 9.0 Hz, 2.2 Hz, 1H, H4), 7.50 (t,
J ¼ 6.1 Hz,1H, NH-exchangeable with D2O), 7.64e7.71 (m, 2H, Ar-H),
7.79 (d, J ¼ 2.3 Hz, 1H, H5), 7.85e7.89 (m, 1H, Ar-H), 8.04 (d,
J ¼ 9.0 Hz, 1H, H3), 8.43 (d, J ¼ 5.4 Hz, 1H, H1). 13C NMR (DMSO-d6,
125 MHz): 36.3, 40.3, 99.0, 117.9 (d, J ¼ 12.4 Hz), 118.0, 120.0 (d,
J ¼ 3.1 Hz), 122.8 (d, J ¼ 19.5 Hz), 124.2, 124.7, 127.8, 134.6 (d,
J ¼ 1.2 Hz), 137.8 (d, J ¼ 7.7 Hz), 149.4, 150.3, 152.2, 157.0 (d,
J ¼ 258.8 Hz), 165.2, 167.3 (d, J ¼ 2.7 Hz). C19H13ClFN3O2 [M]þ
369.0680. Found 369.0688.
anhydrous Na2SO4 and concentrated under reduced pressure to
yield the crude product which was re-crystallized using absolute
ethanol.
3.2.1. 2-(2-(7-chloroquinolin-4-ylamino)ethyl)isoindoline-1,3-
dione (5a)
Light yellow solid, M.P ¼ 159-160 OC 1H NMR (DMSO-d6,
400 MHz): 3.52e3.57 (m, 2H, CH2), 3.78 (t, J ¼ 6.2 hz, 2H, CH2), 6.60
(d, J ¼ 5.4 hz, 1H, H2), 7.38 (dd, J ¼ 9.0 hz, 2.2 hz, 1H, H2), 7.48 (t,
J ¼ 4.8 hz, 1H, NH-exchangeable with D2O), 7.74 (d, J ¼ 2.2 hz, 1H,
H5), 7.77e7.82 (m, 4H, Ar-H), 8.00 (d, J ¼ 9.0 hz, 1H, H3), 8.37 (d,
J ¼ 5.4 hz, 1H, H1). 13C NMR (DMSO-d6, 100 MHz): 36.3, 40.6, 99.1,
118.0, 123.5, 124.3, 124.8, 127.9, 132.3, 134.0, 134.8, 149.5, 150.4,
152.3, 168.5. C19H14ClN3O2 [M]þ 351.0775. Found 351.0781.
3.2.7. 2-(3-(7-chloroquinolin-4-ylamino)propyl)-4-
fluoroisoindoline-1,3-dione (5g)
Light yellow solid, M.P ¼ 117-118 OC 1H NMR (DMSO-d6,
400 MHz): 1.94e2.01 (m, 2H, CH2), 3.27e3.30 (m, 2H, CH2), 3.65 (t,
J ¼ 6.8 Hz, 2H, CH2), 6.43 (d, J ¼ 5.5 Hz,1H, H2), 7.29 (t, J ¼ 5.4 Hz,1H,
NH-exchangeable with D2O), 7.38 (dd, J ¼ 8.8 Hz, 2.2 Hz, 1H, H4),
7.55e7.63 (m, 2H, Ar-H), 7.71 (d, J ¼ 2.2 Hz, 1H, H5), 7.77e7.82 (m,
3.2.2. 2-(3-(7-chloroquinolin-4-ylamino)propyl)isoindoline-1,3-
dione (5b)
Light yellow solid, M.P ¼ 130-131 OC 1H NMR (DMSO-d6,
400 MHz): 2.00e2.07 (m, 2H, CH2), 3.53e3.58 (m, 2H, CH2), 3.69 (t,
J ¼ 6.8 Hz, 2H, CH2), 6.83 (d, J ¼ 7.2 Hz, 1H, H2), 7.69 (dd, J ¼ 9.0 Hz,
2.2 Hz, 1H, H4), 7.75e7.80 (m, 4H, Ar-H), 8.01 (d, J ¼ 1.9 Hz, 1H, H5),
8.49 (d, J ¼ 9.1 Hz, 1H, H3), 8.55 (d, J ¼ 5.3 Hz, 1H, H1), 9.43 (t,
J ¼ 5.5 Hz, 1H, NH-exchangeable with D2O). 13C NMR (DMSO-d6,
100 MHz): 26.9, 35.8, 41.6, 99.2, 115.9, 119.5, 123.4, 126.2, 127.3,
132.1, 134.8, 138.4, 138.9, 143.3, 155.8, 168.5. C20H16ClN3O2 [M]þ
365.0931. Found 365.0920.
1H, Ar-H), 8.16 (d, J ¼ 9.0 Hz, 1H, H3), 8.33 (d, J ¼ 5.4 Hz, 1H, H1). 13
C
NMR (DMSO-d6, 100 MHz): 27.0, 36.3, 40.6, 99.3, 117.8, 118.0 (d,
J ¼ 12.7 Hz), 119.9 (d, J ¼ 2.7 Hz), 122.8 (d, J ¼ 19.6 Hz), 124.5, 124.6,
127.7, 134.2 (d, J ¼ 56.8 Hz), 137.7 (d, J ¼ 7.7 Hz), 149.1, 150.6, 152.1,
157.0 (d, J ¼ 259.8 Hz), 165.3, 167.4 (d, J ¼ 2.4 Hz). C20H15ClFN3O2
[M]þ 383.0837. Found 383.0841.
3.2.8. 2-(4-(7-chloroquinolin-4-ylamino)butyl)-4-
3.2.3. 2-(4-(7-chloroquinolin-4-ylamino)butyl)isoindoline-1,3-
dione (5c)
fluoroisoindoline-1,3-dione (5h)
Light yellow solid, M.P ¼ 107-108 OC 1H NMR (DMSO-d6,
400 MHz): 1.56e1.60 (m, 4H, 2CH2), 3.26e3.29 (m, 2H, CH2), 3.83 (t,
J ¼ 6.4 Hz, 2H, CH2), 6.61 (d, J ¼ 5.4 Hz, 1H, H2), 7.43 (dd, J ¼ 9.1 Hz,
2.2 Hz, 1H, H2), 7.50 (t, J ¼ 6.2 Hz, 1H, NH-exchangeable with D2O),
7.64e7.71 (m, 2H, Ar-H), 7.79 (d, J ¼ 2.2 Hz, 1H, H5), 7.83e7.88 (m,
Light yellow solid, M.P ¼ 115-116 OC 1H NMR (DMSO-d6,
400 MHz): 1.62e1.71 (m, 4H, 2CH2), 3.48e3.52 (m, 2H, CH2), 3.58 (t,
J ¼ 6.2 Hz, CH2), 6.83 (d, J ¼ 7.2 Hz, 1H, H2), 7.33 (dd, J ¼ 9.0 Hz,
2.1 Hz, 1H, H4), 7.77e7.80 (m, 4H, Ar-H), 7.99 (d, J ¼ 2.1 Hz, 1H, H5),
8.46 (d, J ¼ 7.1 Hz, 1H, H1), 8.57 (d, J ¼ 9.1 Hz, 1H, H3), 9.49 (t,
J ¼ 5.6 Hz, 1H, NH-exchangeable with D2O). 13C NMR (DMSO-d6,
100 MHz): 25.4, 25.9, 37.6, 43.1, 99.1, 115.9, 119.5, 123.4, 126.2, 127.2,
132.0, 134.9, 138.4, 138.9, 143.2, 155.8, 168.5. C21H18ClN3O2 [M]þ
1H, Ar-H), 8.05 (d, J ¼ 9.1 Hz, 1H, H3), 8.45 (d, J ¼ 5.4 Hz, 1H, H1). 13
C
NMR (DMSO-d6, 100 MHz): 25.2, 26.5, 37.4, 42.2, 99.1, 117.8 (d,
J ¼ 12.0 Hz), 118.2, 120.0 (d, J ¼ 3.3 Hz), 122.7 (d, J ¼ 20.0 Hz), 124.2,
124.5, 127.8, 133.7, 134.4 (d, J ¼ 1.2 Hz), 137.8 (d, J ¼ 7.7 Hz), 149.5,

154
A. Rani et al. / European Journal of Medicinal Chemistry 143 (2018) 150e156
150.0, 152.2, 157.3 (d, J ¼ 260.1 Hz), 165.1, 167.3 (d, J ¼ 2.5 Hz).
21H17ClFN3O2 [M]þ 397.0993. Found 397.0989.
7.60e7.64 (m, 1H, Ar-H), 7.69e7.71 (m, 1H, Ar-H), 7.75 (d, J ¼ 2.2 Hz,
1H, H5), 7.88e7.90 (m, 1H, Ar-H), 8.23 (d, J ¼ 9.0 Hz, 1H, H3), 8.35 (d,
C
J ¼ 5.4 Hz, 1H, H1). 13C NMR (DMSO-d6, 125 MHz):
d 25.5, 26.0, 37.9,
3.2.9. 2-(6-(7-chloroquinolin-4-ylamino)hexyl)-4-
fluoroisoindoline-1,3-dione (5i)
42.3, 99.1, 111.2 (d, J ¼ 25.0 Hz), 117.8, 121.5 (d, J ¼ 23.5 Hz), 124.4,
124.5, 126.1 (d, J ¼ 9.7 Hz),127.8, 128.1 (d, J ¼ 2.5 Hz),133.8,135.0 (d,
J ¼ 9.6 Hz), 149.3, 150.5, 152.2, 166.1 (d, J ¼ 246.9 Hz), 167.1 (d,
J ¼ 1.9 Hz), 167.4. C21H17ClFN3O2 [M]þ 397.0993. Found 397.0989.
Light yellow solid, M.P ¼ 94-95 OC 1H NMR (DMSO-d6,
400 MHz): 1.26e1.39 (m, 4H, 2CH2), 1.53e1.63 (m, 4H, 2CH2),
3.16e3.21 (m, 2H, CH2), 3.48 (t, J ¼ 6.5 Hz, 2H, CH2), 6.39 (d,
J ¼ 5.5 Hz, 1H, H2), 7.33e7.39 (m, 2H, H4 þ NH-exchangeable with
D2O), 7.60e7.64 (m, 2H, Ar-H), 7.70 (d, J ¼ 2.2 Hz, 1H, H5), 7.78e7.82
(m, 1H, Ar-H), 8.22 (d, J ¼ 9.0 Hz, 1H, H3), 8.31 (d, J ¼ 5.4 Hz, 1H, H1).
13C NMR (DMSO-d6, 100 MHz): 26.5, 26.6, 28.1, 28.3, 38.0, 42.8,
99.0, 117.8, 117.9 (d, J ¼ 8.3 Hz), 120.0 (d, J ¼ 2.8 Hz), 122.9 (d,
J ¼ 19.4 Hz), 124.5, 124.7, 127.4, 134.2 (d, J ¼ 39.7 Hz), 137.8 (d,
J ¼ 7.5 Hz), 148.9, 150.8, 151.8, 157.0 (d, J ¼ 260.1 Hz), 165.2, 167.4 (d,
J ¼ 2.5 Hz). C23H21ClFN3O2 [M]þ 425.1306. Found 425.1311.
3.2.14. 2-(6-(7-chloroquinolin-4-ylamino)hexyl)-5-
fluoroisoindoline-1,3-dione (5n)
Light yellow solid, M.P ¼ 112-113 OC 1H NMR (DMSO-d6,
500 MHz): 1.31e1.41 (m, 4H, 2CH2), 1.58e1.65 (m, 4H, 2CH2),
3.20e3.24 (m, 2H, CH2), 3.56 (t, J ¼ 7.0 Hz, 2H, CH2), 6.42 (d,
J ¼ 5.5 Hz, 1H, H2), 7.29 (t, J ¼ 5.3 Hz, 1H, NH-exchangeable with
D2O), 7.41 (dd, J ¼ 8.9 Hz, 2.2 Hz, 1H, H4), 7.60e7.64 (m, 1H, Ar-H),
7.70e7.72 (m, 1H, Ar-H), 7.75 (d, J ¼ 2.2 Hz, 1H, H5), 7.88e7.91 (m,
1H, Ar-H), 8.25 (d, J ¼ 9.0 Hz, 1H, H3), 8.36 (d, J ¼ 5.4 Hz, 1H, H1). 13
C
3.2.10. 2-(8-(7-chloroquinolin-4-ylamino)octyl)-4-
NMR (DMSO-d6, 125 MHz): d 26.5, 26.6, 28.0, 28.3, 38.0, 42.8, 99.0,
fluoroisoindoline-1,3-dione (5j)
111.3 (d, J ¼ 25.0Hz), 117.7, 121.5 (d, J ¼ 23.4 Hz), 124.5, 124.6, 126.1
(d, J ¼ 9.7 Hz), 127.3, 128.2 (d, J ¼ 2.5 Hz), 134.0, 135.0 (d, J ¼ 9.6 Hz),
148.8, 150.8, 151.8, 166.1 (d, J ¼ 251.5 Hz), 167.1 (d, J ¼ 2.7 Hz), 167.4.
Yellow Semisolid, 1H NMR (DMSO-d6, 400 MHz): 1.18e1.28 (m,
8H, 4CH2), 1.51e1.65 (m, 4H, 2CH2), 3.40e3.44 (m, 2H, CH2), 3.48 (t,
J ¼ 7.0 Hz, 2H, CH2), 6.74 (d, J ¼ 6.8 Hz, 1H, H2), 7.59e7.67 (m, 3H,
2Ar-H þ H4), 7.80e7.85 (m, 1H, Ar-H), 7.91 (d, J ¼ 2.2 Hz, 1H, H5),
8.45 (d, J ¼ 6.7 Hz, 1H, H1), 8.50 (d, J ¼ 9.1 Hz, 1H, H3), 8.98 (t,
J ¼ 6.6 Hz, 1H, NH-exchangeable with D2O). 13C NMR (DMSO-d6,
100 MHz): 26.4, 26.8, 28.3, 28.8, 28.9, 29.3, 37.9, 43.2, 99.2, 117.5 (d,
J ¼ 12.4 Hz), 118.3, 120.3 (d, J ¼ 3.3 Hz),122.5 (d, J ¼ 12.2 Hz), 124.0,
124.2, 127.4, 133.3, 134.4 (d, J ¼ 1.4 Hz), 137.5 (d, J ¼ 7.7 Hz), 149.1,
150.3, 151.9, 157.5 (d, J ¼ 259.8 Hz), 165.2, 167.0 (d, J ¼ 2.2 Hz).
C
23H21ClFN3O2 [M]þ 425.1306. Found 425.1311.
3.2.15. 2-(8-(7-chloroquinolin-4-ylamino)octyl)-5-
fluoroisoindoline-1,3-dione (5o)
Yellow Semisolid liquid, 1H NMR (DMSO-d6, 400 MHz):
1.47e1.54 (m, 8H, 4CH2), 1.58e1.63 (m, 4H, 4CH2), 3.24e3.28 (m,
2H, CH2), 3.50 (t, J ¼ 7.1 Hz, 2H, CH2), 6.51 (d, J ¼ 5.9 Hz, 1H, H2), 7.47
(dd, J ¼ 8.9 Hz, 2.1 Hz, 1H, H4), 7.57e7.62 (m, 1H, Ar-H), 7.69e7.72
(m, 1H, Ar-H), 7.77 (d, J ¼ 2.1 Hz, 1H, H5), 7.81 (t, J ¼ 4.6 Hz, 1H, NH-
exchangeable with D2O), 7.86e7.89 (m,1H, Ar-H), 8.30 (d, J ¼ 9.1 Hz,
1H, H3), 8.36 (d, J ¼ 5.7 Hz, 1H, H1). 13C NMR (DMSO-d6, 100 MHz):
C
25H25ClFN3O2 [M]þ 453.1619. Found 453.1625.
3.2.11. 2-(2-(7-chloroquinolin-4-ylamino)ethyl)-5-
fluoroisoindoline-1,3-dione (5k)
d 26.3, 26.7, 28.2, 28.9, 30.1, 30.3, 37.5, 42.1, 99.1, 111.2 (d,
Light yellow solid, M.P ¼ 148-149 OC 1H NMR (DMSO-d6,
400 MHz): 3.16e3.21 (m, 2H, CH2), 3.50 (t, J ¼ 7.1 Hz, 2H, CH2), 6.38
(d, J ¼ 5.5 Hz, 1H, H2), 7.24 (t, J ¼ 5.3 Hz, 1H, NH-exchangeable with
D2O), 7.36 (dd, J ¼ 9.0 Hz, 2.2 Hz, 1H, H4), 7.56e7.59 (m, 1H, Ar-H),
7.62e7.65 (m, 1H, Ar-H), 7.70 (d, J ¼ 2.2 Hz, 1H, H5), 7.78e7.82 (m,
J ¼ 24.6Hz), 117.8, 121.4 (d, J ¼ 23.8 Hz), 124.3, 124.4, 126.0 (d,
J ¼ 9.8 Hz), 127.5, 128.1 (d, J ¼ 2.5 Hz), 134.1, 135.0 (d, J ¼ 9.8 Hz),
148.7, 150.6, 151.6, 166.0 (d, J ¼ 251.2 Hz), 167.0 (d, J ¼ 2.6 Hz), 167.5.
C
25H25ClFN3O2 [M]þ 453.1619. Found 453.1625.
1H, Ar-H), 8.20 (d, J ¼ 9.0 Hz, 1H, H3), 8.31 (d, J ¼ 5.4 Hz, 1H, H1). 13
C
3.2.16. 4,5,6,7-Tetrachloro-2-(2-(7-chloroquinolin-4-ylamino)ethyl)
isoindoline-1,3-dione (5p)
NMR (DMSO-d6, 100 MHz):
d
36.4, 41.4, 99.1, 111.5 (d, J ¼ 25.1 Hz),
117.5, 121.7 (d, J ¼ 23.5 Hz), 125.3, 125.4, 126.3 (d, J ¼ 9.5 Hz), 127.1,
128.4 (d, J ¼ 2.6 Hz), 135.2 (d, J ¼ 9.6 Hz), 137.7, 145.7, 149.7, 155.0,
166.1 (d, J ¼ 235.8 Hz), 167.2 (d, J ¼ 2.7 Hz), 167.4. C19H13ClFN3O2
[M]þ 369.0680. Found 369.0688.
Light yellow solid, M.P ¼ 154-155 OC 1H NMR (DMSO-d6,
500 MHz): 3.65e3.68 (m, 2H, CH2), 3.88 (t, J ¼ 6.1 Hz, 2H, CH2), 6.73
(d, J ¼ 5.6 Hz, 1H, H2), 7.50 (dd, J ¼ 2.0 Hz, 8.9 Hz, 1H, H4), 7.69 (t,
J ¼ 5.3 Hz, 1H, NH-exchangeable with D2O), 7.85 (d, J ¼ 1.9 Hz, 1H,
H5), 8.33 (d, J ¼ 8.0 Hz, 1H, H3), 8.50 (d, J ¼ 5.5 Hz, 1H, H1). 13C NMR
(DMSO-d6, 125 MHz): 36.7, 40.2, 99.0, 117.8, 124.3, 124.9, 127.1,
128.5, 128.6, 134.1, 136.6, 148.5, 150.8, 151.5, 163.9. C19H10Cl5N3O2
[M]þ 488.9186. Found 488.9178. [Mþ2]þ 490.9157. Found 490.9148.
3.2.12. 2-(3-(7-chloroquinolin-4-ylamino)propyl)-5-
fluoroisoindoline-1,3-dione (5l)
Light yellow solid, M.P ¼ 139-140 OC 1H NMR (DMSO-d6,
400 MHz): 1.94e2.00 (m, 2H, CH2), 3.27e3.30 (m, 2H, CH2), 3.66 (t,
J ¼ 6.6 Hz, 2H, CH2), 6.42 (d, J ¼ 5.4 Hz, 1H, H2), 7.32e7.39 (m, 2H,
NH-exchangeable with D2O þ H4), 7.53e7.58 (m, 1H, Ar-H),
7.62e7.64 (m, 1H, Ar-H), 7.71 (d, J ¼ 1.1 Hz, 1H, H5), 7.80e7.84 (m,
3.2.17. 4,5,6,7-Tetrachloro-2-(3-(7-chloroquinolin-4-ylamino)
propyl)isoindoline-1,3-dione (5q)
Light yellow solid, M.P ¼ 142-143 OC 1H NMR (DMSO-d6,
400 MHz): 1.59e1.64 (m, 2H, CH2), 3.15e3.20 (m, 2H, CH2), 3.51 (t,
J ¼ 6.9 Hz, 2H, CH2), 6.79 (d, J ¼ 5.3 Hz, 1H, H2), 7.67 (dd, J ¼ 1.8 Hz,
9.1 Hz,1H, H4), 7.98 (d, J ¼ 2.1 Hz,1H, H5), 8.46 (d, J ¼ 6.9 Hz,1H, H1),
8.60 (d, J ¼ 9.4 Hz, 1H, H3), 9.38 (t, J ¼ 5.6 Hz, 1H, NH-exchangeable
with D2O). 13C NMR (DMSO-d6, 100 MHz): 26.1, 37.3, 40.8, 99.4,
117.5, 124.4, 124.6, 127.1, 131.3, 131.4, 134.2, 136.6, 148.4, 150.7, 151.5,
164.2. C20H12Cl5N3O2 [M]þ 502.9343. Found 502.9349. [Mþ2]þ
504.9313. Found 504.9119.
1H, Ar-H), 8.13 (d, J ¼ 8.9 Hz, 1H, H3), 8.31 (d, J ¼ 5.2 Hz, 1H, H1). 13
C
NMR (DMSO-d6, 100 MHz):
d 27.0, 36.4, 40.7, 99.2, 111.3 (d,
J ¼ 25.0 Hz), 117.7, 121.5 (d, J ¼ 25.01 Hz), 124.5, 124.7, 126.1 (d,
J ¼ 9.6 Hz), 127.3, 128.3 (d, J ¼ 2.0 Hz), 134.2, 135.1 (d, J ¼ 9.7 Hz),
148.8, 150.7, 151.8, 166.2 (d, J ¼ 251.8 Hz), 167.2 (d, J ¼ 1.8 Hz), 167.6.
C
20H15ClFN3O2 [M]þ 383.0837. Found 383.0841.
3.2.13. 2-(4-(7-chloroquinolin-4-ylamino)butyl)-5-
fluoroisoindoline-1,3-dione (5m)
Light yellow solid, M.P ¼ 121-122 OC 1H NMR (DMSO-d6,
500 MHz): 1.63e1.76 (m, 4H, 2CH2), 3.26e3.30 (m, 2H, CH2), 3.62 (t,
J ¼ 6.4 Hz, 2H, CH2), 6.44 (d, J ¼ 5.4 Hz,1H, H2), 7.29 (t, J ¼ 5.4 Hz,1H,
NH-exchangeable with D2O), 7.42 (dd, J ¼ 8.9 Hz, 2.3 Hz, 1H, H4),
3.2.18. 4,5,6,7-Tetrachloro-2-(4-(7-chloroquinolin-4-ylamino)
butyl)isoindoline-1,3-dione (5r)
Light yellow solid, M.P ¼ 140-141 OC 1H NMR (DMSO-d6,
500 MHz): 1.66e1.79 (m, 4H, 2CH2), 3.25e3.29 (m, 2H, CH2), 3.60 (t,

A. Rani et al. / European Journal of Medicinal Chemistry 143 (2018) 150e156
155
J ¼ 6.4 Hz, 2H, CH2), 6.42 (d, J ¼ 5.5 Hz, 1H, H2), 7.42 (dd, J ¼ 2.2 Hz,
9.0 Hz, 1H, H4) 7.47 (t, J ¼ 5.5 Hz, 1H, NH-exchangeable with D2O),
7.66 (d, J ¼ 2.2 Hz, 1H, H5), 8.19 (d, J ¼ 9.1 Hz, 1H, H3), 8.32 (d,
J ¼ 5.2 Hz, 1H, H1). 13C NMR (DMSO-d6, 125 MHz): 24.8, 25.3, 38.6,
42.2, 99.2, 117.5, 124.4, 124.6, 127.4, 128.2, 128.4, 134.0, 138.4, 148.8,
150.4, 151.7, 163.9. C21H14Cl5N3O2 [M]þ 516.9499. Found 516.9492.
[Mþ2]þ 518.9470. Found 518.9462.
133.6, 134.0, 137.4, 148.5, 150.4, 151.4, 164.8. C23H18Br4ClN3O2 [M]þ
722.7780. Found 722.7789. [Mþ2]þ 724.7760. Found 724.7767.
3.2.24. 2-(2-(7-chloroquinolin-4-ylamino)ethyl)-4-
nitroisoindoline-1,3-dione (5x)
Light yellow solid, M.P ¼ 111-112 OC 1H NMR (DMSO-d6,
500 MHz): 3.60e3.64 (m, 2H, CH2), 3.83 (t, J ¼ 6.1 Hz, 2H, CH2), 6.69
(d, J ¼ 5.5 Hz, 1H, H2), 7.46 (dd, J ¼ 8.9 Hz, 1.9 Hz, 1H, H4), 7.64 (t,
J ¼ 6.3 Hz, 1H, NH-exchangeable with D2O), 7.81 (d, J ¼ 1.9 Hz, 1H,
H5), 8.03e8.06 (m, 2H, Ar-H), 8.15 (d, J ¼ 7.4 Hz, 1H, Ar-H), 8.29 (d,
J ¼ 8.1 Hz, 1H, H3), 8.46 (d, J ¼ 5.5 Hz, 1H, H1). 13C NMR (DMSO-d6,
125 MHz): 36.7, 40.4, 99.0, 117.8, 123.5, 124.3, 124.9, 127.1, 127.2,
128.5, 134.1, 134.3, 136.6, 144.7, 148.5, 150.8, 151.5, 163.9, 166.4.
3.2.19. 4,5,6,7-Tetrachloro-2-(6-(7-chloroquinolin-4-ylamino)
hexyl)isoindoline-1,3-dione (5s)
Light yellow solid, M.P ¼ 128-129 OC 1H NMR (DMSO-d6,
400 MHz): 1.25e1.38 (m, 4H, 2CH2), 1.43e1.66 (m, 4H, 2CH2),
3.15e3.20 (m, 2H, CH2), 3.43 (t, J ¼ 6.4 Hz, 2H, CH2), 6.76 (d,
J ¼ 6.6 Hz, 1H, H2), 7.63 (dd, J ¼ 2.2 Hz, 8.9 Hz, 1H, H4), 7.94 (d,
J ¼ 2.2 Hz, 1H, H5), 8.42 (d, J ¼ 5.4 Hz, 1H, H1), 8.54 (d, J ¼ 9.4 Hz, 1H,
H3), 9.20 (t, J ¼ 5.3 Hz, 1H, NH-exchangeable with D2O). 13C NMR
(DMSO-d6, 100 MHz): 26.3, 26.5, 27.9, 28.0, 38.6, 43.5, 99.0, 116.1,
126.0, 126.1, 126.8, 128.3, 128.4, 132.9, 137.8, 148.8, 150.5, 151.4,
163.9. C23H18Cl5N3O2 [M]þ 544.9812 Found 544.9821. [Mþ2]þ
546.9783. Found 546.9788.
C
19H13ClN4O4 [M]þ 396.0625. Found 396.0618.
3.2.25. 2-(6-(7-chloroquinolin-4-ylamino)hexyl)-4-
nitroisoindoline-1,3-dione (5y)
Yellow Semisolid liquid, 1H NMR (DMSO-d6, 400 MHz):
1.28e1.33 (m, 4H, 2CH2), 1.52e1.61 (m, 4H, 2CH2), 3.25e3.29 (m,
2H, CH2), 3.49 (t, J ¼ 7.0 hz, 1H, CH2), 6.53 (d, J ¼ 6.1 hz, 1H, H2), 7.44
(dd, J ¼ 9.1 hz, 1.8 hz, 1H, H4), 7.56e7.64 (m, 2H, NH-exchangeable
with D2O þ H5), 7.78e7.83 (m, 2H, Ar-H), 8.07 (d, J ¼ 6.9 hz, 1H, Ar-
H), 8.31e8.36 (m, 2H, H1 þ H3). 13C NMR (DMSO-d6, 100 MHz): 26.5,
26.6, 28.0, 28.2, 38.0, 43.1, 99.0, 117.1, 122.8, 123.0, 124.0, 124.6,
125.2, 125.5, 134.4, 135.6, 137.8, 145.3, 148.7, 152.6, 155.7, 165.3,
167.4. C23H21ClN4O4 [M]þ 452.1251.Found 452.1260.
3.2.20. 4,5,6,7-Tetrabromo-2-(2-(7-chloroquinolin-4-ylamino)
ethyl)isoindoline-1,3-dione (5t)
Light yellow solid, M.P ¼ 173-174 OC 1H NMR (DMSO-d6,
400 MHz): 3.26e3.30 (m, 2H, CH2), 3.67 (t, J ¼ 6.6 hz, 2H, CH2), 6.37
(d, J ¼ 5.5 hz, 1H, H2), 7.22 (t, J ¼ 4.6 hz, 1H, NH-exchangeable with
D2O), 7.28 (dd, J ¼ 2.0 hz, 9.0 hz, 1H, H4), 7.65 (d, J ¼ 2.2 hz, 1H, H5),
8.02 (d, J ¼ 9.0 hz, 1H, H3), 8.30 (d, J ¼ 5.4 hz, 1H, H1). 13C NMR
(DMSO-d6, 100 MHz): 37.2, 40.8, 99.3, 117.5, 120.6, 124.3, 124.5,
127.0, 131.2, 134.1, 136.5, 148.3, 150.6, 151.4, 164.1. C19H10Br4ClN3O2
[M]þ 666.7154. Found 666.7149. [Mþ2]þ 668.7134. Found
668.7125.
4. Material and methods
4.1. Methods for assessment of anti-plasmodial activity of test
compounds
The W2 strain of P. falciparum was cultured in RPMI-1640 me-
dium with 10% human serum, following standard methods, and
parasites were synchronized with 5% D-sorbitol [19]. Beginning at
the ring stage, microwell cultures were incubated with different
concentrations of compounds for 48 h. The compounds were added
from DMSO stocks; the maximum concentration of DMSO used was
0.1%. Controls without inhibitors included 0.1% DMSO. After 48 h
when control cultures had progressed to new rings, the culture
medium was removed, and cultures were incubated for 48 h with
1% formaldehyde in PBS, pH 7.4, at room temperature. Fixed para-
sites were then transferred to 0.1% Triton X-100 in PBS containing
1 nM YOYO-1 dye (Molecular Probes). Parasitemia was determined
from dot plots (forward scatter vs. fluorescence) acquired on a
FACSort flow cytometer using Cell Quest software (Beckton Dick-
inson). IC50 values for growth inhibition were determined from
plots of percent control parasitemia over inhibitor concentration
using the Prism 3.0 program, (GraphPad Software), with data from
duplicate experiments fitted by non-linear regression [20].
3.2.21. 4,5,6,7-Tetrabromo-2-(3-(7-chloroquinolin-4-ylamino)
propyl)isoindoline-1,3-dione (5u)
Light yellow solid, M.P ¼ 161-162 OC 1H NMR (DMSO-d6,
500 MHz): 2.03e2.08 (m, 2H, CH2), 3.33e3.37 (m, 2H, CH2), 3.72 (t,
J ¼ 6.6 hz, 2H, CH2), 6.42 (d, J ¼ 5.4 hz, 1H, H2), 7.28 (t, J ¼ 6.6 hz, 1H,
NH-exchangeable with D2O), 7.32 (dd, J ¼ 9.0 hz, 2.0 hz, 1H, H4),
7.69 (d, J ¼ 2.2 hz, 1H, H5), 8.06 (d, J ¼ 8.9 hz, 1H, H3), 8.34 (d,
J ¼ 5.5 hz, 1H, H1). 13C NMR (DMSO-d6, 125 MHz): 26.0, 37.3, 40.7,
99.4, 117.6, 120.6, 124.2, 124.5, 127.3, 131.3, 134.0, 136.5, 148.8, 150.4,
151.8, 164.1. C20H12Br4ClN3O2 [M]þ 680.7311. Found 680.7320.
[Mþ2]þ 682.7290. Found 682.7295.
3.2.22. 4,5,6,7-Tetrabromo-2-(4-(7-chloroquinolin-4-ylamino)
butyl)isoindoline-1,3-dione (5v)
Light yellow solid, M.P ¼ 155-156 OC 1H NMR (DMSO-d6,
400 MHz): 1.69e1.75 (m, 4H, 2CH2), 3.20e3.25 (m, 2H, CH2), 3.52 (t,
J ¼ 6.3 Hz, 2H, CH2), 6.87 (d, J ¼ 5.5 Hz, 1H, H2), 7.73 (dd, J ¼ 9.4 Hz,
2.0 Hz,1H, H4), 7.99 (d, J ¼ 2.0 Hz,1H, H5), 8.54 (d, J ¼ 9.1 Hz,1H, H3),
8.59 (d, J ¼ 5.6 Hz, 1H, H1), 9.46 (t, J ¼ 5.2 Hz, 1H, NH-exchangeable
with D2O). 13C NMR (DMSO-d6, 100 MHz): 25.0, 25.4, 38.7, 42.3,
99.2, 117.6, 120.7, 124.5, 124.9, 127.5, 131.2, 134.1, 136.7, 148.9, 150.8,
151.8, 164.3. C21H14Br4ClN3O2 [M]þ 694.7467. Found 694.7461.
[Mþ2]þ 696.7447. Found 696.7440.
4.2. Cytotoxicity assay
Cell viability was determined using J774 murine macrophage
cells which were grown in Dulbecco's modified Eagle's medium
(DMEM, Gibco, USA), supplemented with 10% de-complemented
fetal calf serum, under a 5% CO2 atmosphere. Cells were seeded in
3.2.23. 4,5,6,7-Tetrabromo-2-(6-(7-chloroquinolin-4-ylamino)
hexyl)isoindoline-1,3-dione (5w)
96-well plates at a density of 2 ꢁ 104 cells/well in 160
mL medium
and incubated overnight at 37 ꢀC to allow cells to adhere. Com-
pounds (dissolved in DMSO) were freshly diluted to appropriate
Light yellow solid, M.P ¼ 115-116 OC 1H NMR (DMSO-d6,
400 MHz): 1.28e1.41 (m, 4H, 2CH2), 1.52e1.65 (m, 4H, 2CH2),
3.34e3.40 (m, 2H, CH2), 3.51 (t, J ¼ 7.0 hz, 2H, CH2), 6.63 (d,
J ¼ 6.3 hz, 1H, 7.57 (dd, J ¼ 1.7 hz, 9.1 hz, 1H, H4), 7.84 (d, J ¼ 1.6 hz,
1H, H5), 8.39e8.42 (m, 2H, H1 þ H3). 13C NMR (DMSO-d6, 100 MHz):
26.1, 26.3, 27.7, 27.9, 37.6, 42.4, 98.6, 117.4, 119.6, 124.1, 124.3, 127.0,
concentrations in DMEM, so as to allow addition of 20
of the diluted compounds to the cells that resulted in final com-
pound concentrations of 100 g/mL, 50 g/mL, 25 g/mL, 12.5 g/
mL, 6.25 g/mL and 3.125 g/mL. The maximum final concentration
of DMSO was 1% (v/v). After 24 h incubation at 37 ꢀC, 20
L of 1 mg/
mL volumes
m
m
m
m
m
m
m

156
A. Rani et al. / European Journal of Medicinal Chemistry 143 (2018) 150e156
[3] R.M. Beteck, F.J. Smit, R.K. Haynes, D.D. N’Da, C Malar. J. 13 (2014) 339.
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P.M.S. Chauhan, Eur. J. Med. Chem. 46 (2011) 676.
mL resazurin (Sigma, Germany) was added to each well and the
cells incubated for an additional 2 h at 37 ꢀC. Fluorescence was
measured in a Polarstar Omega fluorometer using appropriate fil-
ters (540 nm excitation and 590 nm emission wave length). Per-
centage survival was determined by dividing fluorescence values
obtained in the compound containing wells by values obtained for
control wells containing cells incubated with a dilution series of
DMSO (1%, 0.5%, 0.25%, 0.125%, 0.0625%, and 0.03125% v/v). Finally
the values obtained from three independent experiments were
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Acknowledgement
Financial assistance from Council of Scientific and Industrial
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Ref. No. 09/254(0269)/2017-EMR-1 is acknowledged. VK acknowl-
edges Science and Engineering Research Board (SERB), New Delhi
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