Synthesis of novel quinoline-thiosemicarbazide hybrids and evaluation of their biological activities, molecular docking, molecular dynamics, pharmacophore model studies, and ADME-Tox properties

Article abstract of DOI:10.1002/jhet.3855

In the present study, a novel series of N-((substituted)carbamothioyl)-2,4-dimethylquinoline-3-carboxamide (7a-7s) was synthesized by microwave-assisted method. Structure of these derivatives was examined by spectroscopic techniques such as ¹H NMR, ¹³C NMR, FT-IR, and ESI-MS. Further, the novel synthesized compounds were evaluated for their in-vitro biological activities against antibacterial, antifungal, antimalarial, and antituberculosis activity as well as for in-silico study. The antimalarial results demonstrated that compounds 7c and 7q (0.02 μg/mL) have notable potency against Plasmodium falciparum compared with chloroquine (0.02 μg/mL); compounds 7l (0.10 μg/mL), 7e, 7s (0.19 μg/mL), 7b, 7p (0.15 μg/mL), 7a, 7f, and 7f (0.25 μg/mL) also exhibited good activity against P. falciparum compared with quinine (0.26 μg/mL) as standard drug. Docking was performed on PFDHFR-TS, given the effect of compounds against the P. falciparum strain was excellent in comparison with standard drug. Molecular docking suggested that compounds 7b, 7i and 7c, 7e, and 7l closely bind with the active site of protein 3JSU and 4DP3, respectively, and compared with biological activity. We have also carried out molecular dynamics simulation on the best dock compound 7e complex with PDB: 3JSU to check the stability of docked complex and their molecular interaction. The calculated ADME-Tox descriptors for the synthesized compounds validated good pharmacokinetics properties, suggesting that these compounds could be used as hit for the development of the new active agents.

Full text of DOI:10.1002/jhet.3855

Received: 29 August 2019
DOI: 10.1002/jhet.3855
Revised: 20 November 2019
Accepted: 25 November 2019
A R T I C L E
Synthesis of novel quinoline-thiosemicarbazide hybrids
and evaluation of their biological activities, molecular
docking, molecular dynamics, pharmacophore model
studies, and ADME-Tox properties
1
1
1
2
Dhaval B. Patel | Drashti G. Darji | Krupa R. Patel | Dhanji P. Rajani
|
2
1
Smita D. Rajani | Hitesh D. Patel
1
Department of Chemistry, School of
Abstract
Sciences, Gujarat University, Ahmedabad,
India
In the present study, a novel series of N-((substituted)carbamothioyl)-2,
4-dimethylquinoline-3-carboxamide (7a-7s) was synthesized by microwave-assisted
method. Structure of these derivatives was examined by spectroscopic techniques
2
Microcare Laboratory and Tuberculosis
Research Centre, Surat, India
1
13
such as H NMR, C NMR, FT-IR, and ESI-MS. Further, the novel synthesized
compounds were evaluated for their in-vitro biological activities against
antibacterial, antifungal, antimalarial, and antituberculosis activity as well as for in-
silico study. The antimalarial results demonstrated that compounds 7c and 7q
Correspondence
Hitesh D. Patel, Department of Chemistry,
School of Sciences, Gujarat University,
Ahmedabad, Gujarat, India.
Email: drhiteshpatel1@gmail.com
(0.02 μg/mL) have notable potency against Plasmodium falciparum compared with
Funding information
chloroquine (0.02 μg/mL); compounds 7l (0.10 μg/mL), 7e, 7s (0.19 μg/mL), 7b, 7p
(0.15 μg/mL), 7a, 7f, and 7f (0.25 μg/mL) also exhibited good activity against
P. falciparum compared with quinine (0.26 μg/mL) as standard drug. Docking was
performed on PFDHFR-TS, given the effect of compounds against the P. falciparum
strain was excellent in comparison with standard drug. Molecular docking suggested
that compounds 7b, 7i and 7c, 7e, and 7l closely bind with the active site of protein
GUJCOST, Grant/Award Numbers:
MRP/2017-18/2323, GUJCOST/
MRP/2017-18/2323
3JSU and 4DP3, respectively, and compared with biological activity. We have also
carried out molecular dynamics simulation on the best dock compound 7e complex
with PDB: 3JSU to check the stability of docked complex and their molecular interac-
tion. The calculated ADME-Tox descriptors for the synthesized compounds validated
good pharmacokinetics properties, suggesting that these compounds could be used
as hit for the development of the new active agents.
[
2]
[3,4]
[5]
[6]
1
| INTRODUCTION
antiviral, anticancer,
antimalarial, antibacterial,
[
7]
[8]
[9]
antifungal,
inflammatory,
tyrokinase PDGF-RTK inhibiting agents,
activities.
have been employed in the study of metal complex
and bio-organometallic process.
antituberculosis,
antiobesity,
anti-
[
10,11]
[12]
[13]
In the recent decade, quinoline and their derivatives are
much familiar in heterocyclic chemistry. These mole-
cules have great importance to biologists and chemists, as
they are found in the naturally occurring molecules and
also chemically useful moiety having a wide range of bio-
antibiotic,
antihypertensive,
[14]
and anti HIV
[
15,16]
In addition to that, substituted quinolines
[
17]
[
17,18]
Because of their
[
1]
logical activity.
reported to show various biological activities such as
A quinoline derivatives have been
wide range of applications in the various fields such as
industry, medicinal, bioorganic, and synthetic chemistry,
J Heterocyclic Chem. 2020;1–18.
wileyonlinelibrary.com/journal/jhet
© 2020 Wiley Periodicals, Inc.
1

2
PATEL ET AL.
quinoline moiety has become attractive in recent
scenarios.
(USA), and all chemicals were of analytical grade. The
reaction progress was monitored by thin-layer chroma-
tography (TLC) of Merck pre-coated silica gel 60 F254
aluminum sheets, further visualized by UV light. CEM
microwave synthesizer (USA) was used for the synthe-
sis. All products were characterized by their melting
points and spectral data. Melting points were measured
on an Optimelt MPA 100 melting point instrument,
and FT-IR spectra were recorded on a Perkin Elmer
In chemical methods, major effects towards the envi-
ronment are due to the consumption of energy for
[
19]
heating.
To deal with this problem, the development
of efficient methods that use another energy source such
as microwave irradiation are highly attractive. Nowa-
days, microwave-assisted synthesis is a new and quickly
[
19]
developing field in organic synthesis.
This method is
−
1 1
based on critical observation that some reaction methods
proceed step down, faster, and with higher yields under
the microwave irradiation (MWI) as compared with con-
vection method. In many cases, reactions that normally
require many hours at reflux temperature under normal
conditions can be completed within several minutes or
even seconds in a microwave oven, even at comparable
FT-IR 377 spectrometer using KBr pellets in cm . H-
NMR spectra were recorded on a Bruker AV 400 MHz
spectrometer using DMSO-d as a solvent, TMS as the
6
1
3
internal reference and C-NMR spectra were recorded
on a Bruker AV 100 MHz Spectrometer using DMSO-d6
as solvent. Mass spectra (MS) were recorded at Advion
expression CMS (USA). Ethyl acetate is used as mobile
phase, and electron spray ionization (ESI) is used as
the ion source. Elemental analysis was performed on a
CHN elemental analyzer.
[
19]
reaction temperatures.
Quinoline synthesis has
received much focus, and many methods have been devel-
[
20]
oped for the synthesis, such as Skraup,
Doebner-
[21]
[22]
[23]
Miller, Pfitzinger, and Friedlander. Among all the
methods, Friedlander annulation is one of the most popular
methods for the substituted quinoline synthesis.
[
24–27]
2.1.1 | Synthesis of ethyl
2,4-dimethylquinoline-3-carboxylate (3)
[28]
Recently, several Lewis acids,
Bronsted acids, and
[28]
microwave-assisted irradiation were used in the synthe-
sis of quinoline moiety. Friedlander synthesis is an acid-
catalyzed condensation of active methylene carbonyl
compound with α-amino carbonyl compounds.
To a mixture of ethyl acetoacetate (1.0 mmol), alpha-
amino acetophenone (1.0 mmol) and catalytic
amount of p-TSA were collected in ethanol (5 mL);
this solution was irradiated under the microwave at
300 W for 4 minutes. The reaction progress was mon-
itored on the TLC plate. After the completion of the
reaction, the mixture was poured in ice-cold water,
then extract with ethyl acetate (50 × 2 mL), and
the organic layer passed over sodium sulfate, and the
mixture was evaporated to dryness in vacuo. The
crude product was further purified by column
chromatography.
The continuation of our research was aimed at current
manuscript synthesis and biological evaluation of the title
compounds for their future drug development. The
potency of molecule is increased by using dual blocker
hybridization strategy (Figure 1). Herein, we report an
efficient and microwave-assisted synthesis of quinoline
hybrid thiosemicarbazide derivatives from the reaction of
4
ethyl 2,4-dimethylquinoline-3-carboxylate and N -alkyl
and aryl thiosemicarbazides in the presence of glacial
acetic acid under microwave irradiation (Scheme 1). Ethyl
2
,4-dimethylquinoline-3-carboxylate has been synthesized
via condensation between ethyl acetoacetate and α-amino
acetophenone in presence of p-toluenesulfonic acid
2.1.2 | General procedure for the
synthesis of N -alkyl and aryl
thiosemicarbazides (6a-6s)
4
(p-TSA) under microwave irradiation. Biological evalua-
tion of title compounds was carried out in various strains,
after which we conducted molecular docking study and
also ADME-Tox and pharmacophore modeling studies on
the Schrödinger software.
A mixture of various alkyl or aryl isothiocyanate
(0.1 mmol) and hydrazine hydrate (0.1 mmol) was
stirred in ethanol (5 mL) for a few minutes. An inter-
mediate product was synthesized by microwave irradi-
ating at 300 W for 2 to 4 minutes. The reaction
progress was monitored on the TLC plate. After the
completion of the reaction, mixture was poured in ice-
cold water and the solid precipitates were collected.
The crude products were used for the next step without
further purification. Intermediate products were syn-
thesized by the above described method.
2
2
| EXPERIMENTAL
.1 | Methods and materials
All chemicals were purchased from commercial suppliers;
isothiocyanates were purchased from Sigma-Aldrich

PATEL ET AL.
3
2
.1.3 | General procedure for the
synthesis of 2-(2,4-dimethylquinoline-
-carbonyl)-N-substituted
organic layer passed over sodium sulfate, and the solution
was evaporated to dryness in vacuo. The crude product
was further purified by column chromatography. Solid
product was obtained as a final product (Scheme 1).
3
hydrazinecarbothioamide (7a-7s)
4
Intermediate products N -alkyl and aryl thiosemicarbazide
(
6a-6s, 1.0 mmol), ethyl 2,4-dimethylquinoline-3-
2.2 | Spectral data
carboxylate (3, 1.0 mmol), and a few drops of glacial acetic
acid were mixed in ethanol (10 mL) and stirred well for
2.2.1 | 2,4-Dimethyl-N-((4-nitrophenyl)
carbamothioyl)quinoline-
1
minute. This reaction solution was heated under the
microwave irradiation at 300 W with a total irradiation
time of 3 to 8 minutes. Reaction progress was monitored
on the TLC plate at 30-s time interval. After the comple-
tion of the reaction, the mixture was poured in ice-cold
water and extracted with ethyl acetate (50 × 2 mL). The
3-carboxamide (7a)
−1
Yellow solid; Yield: 70%; IR (KBr) λmax (cm ): 3480,
3414 (NH), 1768 (C O), 1617 (C N), 1551 (C S), 1132,
1
1086 (C O); H NMR (400 MHz, DMSO) δ: 11.22 (1H, s,
NH), 10.49 (1H, s, NH), 8.60-8.50 (2H, d, Ar, J = 40),
8.09-8.08 (2H, dd, Ar, J = 4), 7.67-7.65 (1H, d, Ar, J = 8),
7
.45-7.18 (3H, m, Ar), 3.74 (3H, s, CH ), 2.50 (3H, s,
3
13
CH3); C NMR (400 MHz, DMSO) δ: 166.37, 156.50,
47.75, 139.88, 139.17, 138.74, 131.78, 131.46, 130.77, 130.45,
29.89, 129.54, 128.33, 127.84, 127.62, 125.75, 125.42, 123.39,
21.13; Anal. Calcd for C, 59.99%; H, 4.24%; N, 14.73%; S,
1
1
1
8
.43%; Found C, 59.89%; H, 4.28%; N, 14.77%; S, 8.44%; ESI-
+
MS: m/z calculated 380.09, found [M + H] 381.10.
2
.2.2 | N-((4-Chlorophenyl)
carbamothioyl)-2,4-dimethylquinoline-
-carboxamide (7b)
3
−
1
White solid; Yield: 83%; IR (KBr) λmax (cm ): 3279, 3062
(
NH), 1682 (C O), 1588 (C N), 1546 (C S), 1148, 1078
1
(
C O); H NMR (400 MHz, DMSO) δ: 10.99 (1H, s,
NH), 10.21 (1H, s, NH), 8.48 (1H, d, Ar, J = 4),
7
.80-7.64 (4H, m, Ar), 7.45-7.38 (3H, m, Ar), 2.73 (3H, s,
13
CH ), 2.34 (3H, s, CH3); C NMR (400 MHz, DMSO)
3
δ: 156.49, 147.74, 138.75, 136.58, 131.77, 131.46, 130.76,
130.41, 129.88, 129.52, 128.79, 127.80, 127.61, 125.76,
123.40, 121.11; Anal. Calcd for C, 61.70%; H, 4.36%; N,
FIGURE 1 Dual blockers antimalarial drugs and anticancer
molecules
SCHEME 1 Microwave-assisted synthetic strategy for the target compounds (7a-7s)

4
PATEL ET AL.
1
1
1.36%; S, 8.67%; Found C, 61.68%; H, 4.39%; N,
139.52, 138.83, 131.74, 131.46, 130.78, 130.46, 129.86,
129.55, 128.86, 127.87, 127.62, 125.65, 123.32, 121.20;
Anal. Calcd for C, 56.44%; H, 3.74%; N, 10.39%; S, 7.93%;
Found C, 56.40%; H, 3.70%; N, 10.42%; S, 7.89%; ESI-MS:
1.40%; S, 8.61%; ESI-MS: m/z calculated 369.89, found
+
[
M + H] 370.40.
+
m/z calculated 403.03, found [M + H] 404.10.
2
.2.3 | N-((4-Chlorophenyl)
carbamothioyl)-2,4-dimethylquinoline-
-carboxamide (7c)
3
2.2.6 | N-(Tert-butylcarbamothioyl)-
2,4-dimethylquinoline-3-carboxamide (7f)
−
1
White solid; Yield: 76%; IR (KBr) λmax (cm ): 3276 (NH),
804 (C O), 1594 (C N), 1552 (C S), 1152, 1085 (C O);
−
1
1
Brown solid; Yield: 72%; IR (KBr) λmax (cm ): 3480, 3414
1
H NMR (400 MHz, DMSO) δ: 10.83 (1H, s, NH), 10.03
1H, s, NH), 8.50 (1H, d, Ar, J = 4), 8.09 (1H, d, Ar,
(NH), 1785 (C O), 1665 (C N), 1593 (C S), 1137, 1086
1
(
(C O); H NMR (400 MHz, DMSO) δ: 10.83 (1H, s,
J = 4), 7.80-7.78 (2H, dd, Ar, J = 8), 7.65-7.60 (2H, d, Ar,
J = 20), 7.45-7.21 (2H, d, Ar, J = 9.6), 2.51 (3H, s, CH3),
NH), 10.03 (1H, s, NH), 8.47 (1H, s, Ar), 8.60 (1H, d,
Ar, J = 4), 7.80-7.78 (2H, dd, Ar, J = 8), 7.69-7.67 (2H, dd,
Ar, J = 8), 7.18 (1H, d, Ar, J = 4), 3.36 (3H, s, CH3),
13
2
.35 (3H, t, CH ), 2.27 (3H, s, CH3); C NMR
3
13
(400 MHz, DMSO) δ: 166.15, 156.42, 147.78, 147.67,
2.50 (3H, s, CH ), 2.30 (9H, s, CH3); C NMR
3
1
1
1
6
6
39.88, 138.70, 131.80, 131.72, 131.46, 130.78, 130.62,
30.42, 130.11, 129.50, 127.77, 127.63, 127.42, 125.82,
23.45, 123.13, 120.96, 118.91; Anal. Calcd for C,
8.74%; H, 5.48%; N, 12.02%; S, 9.18%; Found C,
(400 MHz, DMSO) δ: 156.47, 147.77, 140.73, 138.71,
131.79, 131.45, 130.80, 130.46, 129.89, 129.55, 127.87,
127.40, 125.73, 123.37, 120.87; Anal. Calcd for C,
64.73%; H, 6.71%; N, 13.32%; S, 10.17%; Found C,
64.68%; H, 6.12%; N, 13.38%; S, 10.10%; ESI-MS: m/z cal-
8.60%; H, 5.45%; N, 11.98%; S, 9.20%; ESI-MS: m/z calcu-
+
+
lated 349.45, found [M + H] 350.50.
culated 315.14, found [M + H] 317.25.
2
(
3
.2.4 | 2,4-Dimethyl-N-
propylcarbamothioyl)quinoline-
-carboxamide (7d)
2.2.7 | N-(Benzylcarbamothioyl)-
2,4-dimethylquinoline-3-carboxamide (7g)
−
1
White solid; Yield: 80%; IR (KBr) λmax (cm ): 3285 (NH),
−
1
Off-white solid; Yield: 70%; IR (KBr) λmax (cm ): 3209
1789 (C O), 1659 (C N), 1551 (C S), 1184, 1041 (C O);
1
(NH), 1778 (C O), 1594 (C N), 1533 (C S), 1149, 1086
H NMR (400 MHz, DMSO) δ: 10.08 (1H, s, NH),
1
(C O); H NMR (400 MHz, DMSO) δ: 10.43 (1H, s,
9.09-9.07 (1H, d, Ar, J = 8), 8.43-8.36 (1H, d, Ar, J = 28),
7.50-7.46 (2H, dd, Ar, J = 16), 7.44-6.82 (4H, m, Ar),
4.88-4.79 (2H, d, CH , J = 36), 2.88 (2H, s, CH ), 2.25
NH), 8.61-7.67 (4H, m, Ar), 7.65-6.85 (4H, m, Ar), 3.73
(3H, s, CH ), 3.52 (3H, s, CH ), 2.50-1.90 (2H, m,
3
3
2
3
13
13
CH ), 1.57 (3H, q, CH3); C NMR (400 MHz, DMSO)
(3H, s, CH ), 1.94 (1H, s, CH3); C NMR (400 MHz,
2
3
δ: 156.47, 147.78, 138.71, 131.78, 131.45, 130.79, 130.45,
29.89, 129.55, 127.86, 127.63, 125.73, 123.38; Anal. Calcd
for C, 63.76%; H, 6.35%; N, 13.94%; S, 10.64%; Found C,
3.60%; H, 6.29%; N, 13.90%; S, 10.61%; ESI-MS: m/z cal-
DMSO) δ: 166.24, 156.50, 147.75, 139.80, 139.17, 138.73,
131.78, 131.46, 130.78, 130.46, 129.89, 129.54, 128.36,
127.85, 127.63, 126.56, 125.75, 125.47, 123.39, 121.14;
Anal. Calcd for C, 68.74%; H, 5.48%; N, 12.02%; S, 9.18%;
Found C, 68.69%; H, 5.45%; N, 11.98%; S, 9.14%; ESI-MS:
1
6
+
culated 301.41, found [M + H] 302.69.
+
m/z calculated 349.12, found [M + H] 350.30.
2
.2.5 | N-((3,4-Dichlorophenyl)
carbamothioyl)-2,4-dimethylquinoline-
-carboxamide (7e)
2.2.8 | N-((4-Methoxyphenyl)
carbamothioyl)-2,4-dimethylquinoline-
3
3
-carboxamide (7h)
−
1
White solid; Yield: 75%; IR (KBr) λmax (cm ): 3195 (NH),
678 (C O), 1594 (C N), 1513 (C S), 1129, 1086 (C O);
−
1
1
Light brown solid; Yield: 81%; IR (KBr) λmax (cm ): 3397
(NH), 1819 (C O), 1671 (C N), 1550 (C S), 1130, 1086
(C O); H NMR (400 MHz, DMSO) δ: 11.22 (1H, s,
1
H NMR (400 MHz, DMSO) δ: 11.23 (1H, s, NH), 10.29
1H, s, NH), 8.47 (1H, s, Ar), 8.09 (1H, d, Ar, J = 4),
1
(
7
7
.80-7.78 (2H, dd, Ar, J = 8), 7.80-7.81 (1H, d, Ar, J = 4),
NH), 9.55 (1H, s,
7.71-6.90 (4H, m, Ar), 3.74 (3H, s, OCH ), 2.50 (3H, s,
NH), 8.61-7.85 (4H, m, Ar),
.80-7.40 (3H, m, Ar), 2.59 (3H, s, CH ), 2.35 (3H, s,
3
3
13
13
CH3); C NMR (400 MHz, DMSO) δ: 156.56, 147.71,
CH ), 1.30 (3H, s, CH3); C NMR (400 MHz, DMSO)
3

PATEL ET AL.
5
δ: 156.57, 147.72, 138.82, 135.89, 132.91, 132.57, 131.74,
5.24%; N, 11.50%; S, 8.77%; Found C, 65.69%; H,
1
1
6
6
31.47, 130.77, 130.45, 129.87, 129.55, 128.95, 127.85,
27.61, 125.67, 123.34, 121.23; Anal. Calcd for C,
5.73%; H, 5.24%; N, 11.50%; S, 8.77%; Found C,
5.20%; N, 11.48%; S, 8.71%; ESI-MS: m/z calculated
365.12, found [M + H] 366.87.
+
5.67%; H, 5.20%; N, 11.45%; S, 8.71%; ESI-MS: m/z calcu-
+
lated 365.12, found [M + H] 367.81.
2.2.12 | N-((3-Methoxyphenyl)
carbamothioyl)-2,4-dimethylquinoline-
3
-carboxamide (7l)
2
2
.2.9 | N-((4-Iodophenyl)carbamothioyl)-
,4-dimethylquinoline-3-carboxamide (7i)
−1
White solid; Yield: 82%; IR (KBr) λmax (cm ): 3435 (NH),
763 (C O), 1668 (C N), 1548 (C S), 1131, 1087 (C O);
1
−
1
1
Light brown solid; Yield: 76%; IR (KBr) λmax (cm ):
H NMR (400 MHz, DMSO) δ: 11.05 (1H, s, NH), 10.92
3
1
351, 3274 (NH), 1777 (C O), 1596 (C N), 1553 (C S),
120, 1088 (C O); H NMR (400 MHz, DMSO) δ: 11.00
(1H, s, NH), 8.50-6.75 (8H, m, Ar), 2.50 (S, 3H, CH ), 3.76
(S, 3H, OCH3); C NMR (400 MHz, DMSO) δ: 159.60,
3
1
13
(
2
1H, s, NH), 10.19 (1H, s, NH), 8.48-7.06 (8H, m, Ar),
.89 (3H, s, CH ), 2.27 (S, 3H, CH3); C NMR
3
148.48, 147.76, 138.71, 134.46, 131.93, 131.85, 131.72, 131.46,
131.25, 130.73, 130.37, 130.28, 129.84, 129.81, 129.45, 128.73,
128.39, 128.16, 127.63, 126.59, 125.48, 121.95, 119.44; Anal.
Calcd for C, 65.73%; H, 5.24%; N, 11.50%; S, 8.77%;
Found C, 65.60%; H, 5.20%; N, 11.30%; S, 8.70%; ESI-MS:
13
(400 MHz, DMSO) δ: 166.38, 156.52, 147.69, 138.79,
1
1
31.75, 131.48, 130.76, 130.41, 129.87, 129.51, 127.80,
27.61, 125.71, 125.48, 123.35, 120.83, 120.45; Anal. Calcd
+
for C, 49.47%; H, 3.50%; N, 9.11%; S, 6.95%; Found C,
9.40%; H, 3.48%; N, 9.08%; S, 6.89%; ESI-MS: m/z calcu-
m/z calculated 365.12, found [M + H] 366.87.
4
+
lated 461.01, found [M + H] 462.68.
2
.2.13 | 2,4-Dimethyl-N-
(3,4,5-trichlorophenyl)carbamothioyl)
quinoline-3-carboxamide (7m)
(
2
.2.10 | N-((3,5-Dichlorophenyl)
carbamothioyl)-2,4-dimethylquinoline-
-carboxamide (7j)
−
1
3
White solid; Yield: 80%; IR (KBr) λmax (cm ): 3197 (NH),
668 (C O), 1595 (C N), 1546 (C S), 1131, 1086 (C O);
1
−
1
1
White solid; Yield: 76%; IR (KBr) λmax (cm ): 3335, 3156
H NMR (400 MHz, DMSO) δ: 10.43 (1H, s, NH), 10.05
(
NH), 1659 (C O), 1592 (C N), 1546 (C S), 1157, 1088
(1H, s, NH), 8.48-7.05 (8H, m, Ar), 2.28 (3H, s, CH3),
2.01 (3H, s, CH3); C NMR (400 MHz, DMSO) δ:
1
13
(C O); H NMR (400 MHz, DMSO) δ: 11.19 (1H, s,
NH), 10.31 (1H, s, NH), 8.47-6.85 (8H, m, Ar), 2.22
166.34, 156.49, 147.71, 138.77, 131.76, 131.48, 130.77,
130.41, 129.88, 129.50, 127.77, 127.61, 125.74, 123.38,
120.84; Anal. Calcd for C, 52.01%; H, 3.22%; N, 9.58%; S,
7.31%; Found C, 51.93%; H, 3.20%; N, 9.51%; S, 7.24%;
13
(
3H, s, CH ), 2.14 (3H, s, CH3); C NMR (400 MHz,
3
DMSO) δ: 156.47, 147.77, 140.79, 138.70, 131.79, 131.44,
1
1
3
3
4
30.80, 130.47, 130.10, 129.98, 129.56, 127.88, 127.64,
25.72, 123.36, 120.88; Anal. Calcd for C, 56.44%; H,
.74%; N, 10.39%; S, 7.93%; Found C, 56.41%; H,
.79%; N, 10.29%; S, 7.87%; ESI-MS: m/z calculated
+
ESI-MS: m/z calculated 436.99, found [M + H] 438.21.
+
03.31, found [M + H] 406.32.
2.2.14 | N-((2,4-Dichlorophenyl)
carbamothioyl)-2,4-dimethylquinoline-
3
-carboxamide (7n)
2
.2.11 | N-((2-Methoxyphenyl)
carbamothioyl)-2,4-dimethylquinoline-
-carboxamide (7k)
−
1
White solid; Yield: 74%; IR (KBr) λmax (cm ): 3125 (NH),
3
1801 (C O), 1638 (C N), 1523 (C S), 1159, 1086 (C O);
1
H NMR (400 MHz, DMSO) δ: 11.17 (1H, s, NH), 10.11
−
1
White solid; Yield: 70%; IR (KBr) λmax (cm ): 3362 (NH),
(1H, s, NH), 8.45-6.68 (8H, m, Ar), 2.51 (3H, s, CH3),
13
1
817 (C O), 1661 (C N), 1535 (C S), 1143, 1056 (C O);
2.27 (3H, s, CH3); C NMR (400 MHz, DMSO) δ:
156.49, 147.73, 138.75, 136.59, 131.78, 131.45, 130.77,
130.42, 129.88, 129.52, 128.80, 127.81, 127.62, 125.76,
123.40, 121.11; Anal. Calcd for C, 56.44%; H, 3.74%; N,
10.39%; S, 7.93%; Found C, 56.37%; H, 3.61%; N,
10.34%; S, 7.89%; ESI-MS: m/z calculated 403.31 found
1
H NMR (400 MHz, DMSO) δ: 11.23 (1H, s, NH), 10.08
(1H, s, NH), 8.43-6.94 (8H, m, Ar), 3.81 (3H, s, OCH3),
13
2
.51 (3H, s, CH ), 2.34 (3H, s, CH3); C NMR
3
(400 MHz, DMSO) δ: 147.72, 138.78, 131.74, 131.45,
1
1
30.77, 130.44, 129.86, 129.55, 128.95, 127.85, 127.61,
25.67, 123.33, 121.19; Anal. Calcd for C, 65.73%; H,
+
[M + H] 406.32.

6
PATEL ET AL.
1
2
.2.15 | N-((2,4-Difluorophenyl)
(C S), 1125, 1099 (C O); H NMR (400 MHz, DMSO) δ:
carbamothioyl)-2,4-dimethylquinoline-
-carboxamide (7o)
10.48 (1H, s, NH), 8.31 (1H, s, NH), 7.83-7.38 (4H, m,
Ar), 4.21-4.20 (1H, s, cyclohexyl), 2.51 (3H, s, CH ), 2.20
3H, s, CH ), 1.90-1.13 (m, 10H, cyclohexyl); C NMR
3
(400 MHz, DMSO) δ: 166.12, 156.47, 147.47, 139.21,
139.01, 138.47, 131.38, 131.33, 130.64, 130.32, 129.59,
129.24, 128.34, 127.75, 127.32, 125.68, 125.41, 123.40,
121.68; Anal. Calcd for C, 66.83%; H, 6.79%; N, 12.31%; S,
9.39%; Found C, 66.80%; H, 6.81%; N, 12.27%; S, 9.34%;
3
3
13
(
−
1
Greenish solid; Yield: 83%; IR (KBr) λmax (cm ): 3420,
3
224 (NH), 1785 (C O), 1613 (C N), 1550 (C S), 1130,
1
1
088 (C O); H NMR (400 MHz, DMSO) δ: 11.08 (1H, s,
NH), 10.04 (1H, s, NH), 8.49-6.86 (8H, m, Ar), 2.51
13
(3H, s, CH ), 2.25 (3H, s, CH3); C NMR (400 MHz,
3
+
DMSO) δ: 167.71, 164.34, 156.33, 147.79, 139.91, 138.52,
ESI-MS: m/z calculated 341.16, found [M + H] 342.96.
1
1
1
8
33.22, 131.89, 131.86, 131.37, 130.86, 130.59, 130.14,
29.58, 128.84, 128.53, 127.99, 127.69, 125.58, 123.32,
20.86; Anal. Calcd for C, 61.44%; H, 4.07%; N, 11.31%; S,
2.2.19 | N-Carbamothioyl-
2,4-dimethylquinoline-3-carboxamide (7s)
.63%; Found C, 61.36%; H, 4.01%; N, 11.30%; S, 8.64%;
+
ESI-MS: m/z calculated 371.09, found [M + H] 372.09.
−
1
White solid; Yield: 78%; IR (KBr) λmax (cm ): 3410, 3366
NH), 1784 (C O), 1639 (C N), 1526 (C S), 1114, 1088
(
1
2
2
.2.16 | N-(Ethylcarbamothioyl)-
,4-dimethylquinoline-3-carboxamide (7p)
(C O); H NMR (400 MHz, DMSO) δ: 10.49 (1H, s,
NH), 8.47 (2H, s, NH ), 7.99-7.38 (4H, m, Ar), 2.51
2
1
3
(
3H, s, CH ), 2.26 (3H, s, CH3); C NMR (400 MHz,
3
−1
White solid; Yield: 79%; IR (KBr) λmax (cm ): 3243 (NH), 1773
DMSO) δ: 165.01, 154.87, 147.45, 139.12, 139.01, 138.65,
131.84, 131.23, 130.67, 130.35, 129.78, 129.64, 128.34,
127.68, 127.40, 125.98, 125.46, 123.63, 121.74; Anal. Calcd
for C, 60.21%; H, 5.05%; N, 16.20%; S, 12.36%; Found C,
60.19%; H, 5.01%; N, 16.11%; S, 12.29%; ESI-MS: m/z cal-
1
(
(
7
C O), 1668 (C N), 1544 (C S), 1127, 1088 (C O); H NMR
400 MHz, DMSO) δ: 11.04 (1H, s, NH), 10.11 (1H, s, NH),
.80-7.20 (4H, m, Ar), 3.37 (2H, q, ehtyl-CH ), 2.50 (3H, s,
2
13
CH ), 2.34 (3H, s, CH3); C NMR (400 MHz, DMSO) δ:
3
+
1
1
1
56.82, 156.51, 147.73, 138.87, 131.78, 131.77, 131.46, 130.76,
30.41, 129.87, 129.52, 127.80, 127.61, 125.77, 123.41, 121.13,
13.54; Anal. Calcd for C, 62.69%; H, 5.96%; N, 14.62%; S,
culated 259.08, found [M + H] 260.64.
1
1.16%; Found C, 62.69%; H, 5.89%; N, 14.63%; S, 11.11%; ESI-
3 | BIOLOGICAL ASSAY
+
MS: m/z calculated 287.11, found [M + H] 288.36.
3.1 | In-vitro antibacterial and
antifungal activity
2
(
3
.2.17 | 2,4-Dimethyl-N-
phenylcarbamothioyl)quinoline-
-carboxamide (7q)
The all newly synthesized compounds (7a-7s) were evalu-
ated for their antibacterial activity using the Gram-positive
and Gram-negative strains. Two strains of Gram-positive
bacteria (Staphylococcus aureus MTCC 96 and Streptococ-
cus pyogenes MTCC 442) and two strains of Gram-negative
bacteria (Escherichia coli MTCC 443 and Pseudomonas
aeruginosa MTCC 1688) as well as three fungal strains
(Aspergillus clavatus MTCC 1323, Candida albicans MTCC
227, and Aspergillus niger MTCC 282) by using the
−1
White solid; Yield: 78%; IR (KBr) λmax (cm ): 3318, 3298
NH), 1784 (C O), 1664 (C N), 1546 (C S), 1130, 1087
(
1
(C O); H NMR (400 MHz, DMSO) δ: 10.75 (1H, s, NH),
10.15 (1H, s, NH), 8.50-7.21 (9H, m, Ar), 2.35 (3H, s, CH3),
13
2
1
1
1
.28 (3H, s, CH3); C NMR (400 MHz, DMSO) δ: 165.57,
55.46, 146.11, 140.10, 139.20, 138.45, 131.60, 131.50, 130.45,
30.35, 129.45, 129.23, 128.13, 127.75, 127.41, 125.45, 125.21,
23.12, 121.45; Anal. Calcd for C, 68.03%; H, 5.11%; N,
2.53%; S, 9.56%; Found C, 67.98%; H, 5.08%; N, 12.48%; S,
[
28]
reported agar dilution method.
Ciprofloxacin, ampicil-
lin, and chloramphenicol were used as a standard drug for
the antibacterial activity, and greseofulvin and nystatin
were used as a standard drug for the antifungal activity.
1
+
9.50%; ESI-MS: m/z calculated 335.42, found [M + H] 336.83.
2
.2.18 | N-(Cyclohexylcarbamothioyl)-
3.2 | In-vitro antimalarial and
antituberculosis activity
2
,4-dimethylquinoline-3-carboxamide (7r)
−
1
White solid; Yield: 74%; IR (KBr) λmax (cm ): 3417, 3154
NH), 1724 (C O), 1633 (C N), 1619, 1582 (C S), 1371
The title compounds (7a-7s) were evaluated in in-vitro
antimalarial activity as per the reported method against
(

PATEL ET AL.
7
[
29]
the Plasmodium falciparum strain
and in-vitro anti-
docking using LigPrep module of Schrödinger. The
[
31–33]
tuberculosis activity as per the reported method against
OPLS_2005
force field was used for computing
[30]
the H37RV strain.
Graphical presentation of biological
partial atomic charges. The proteins were prepared for
docking using a protein preparation wizard module in
Maestro. Bond order and formal charges were assigned,
and hydrogen atoms were added to the crystal structure.
Further refinement of the structure OPLS_2005 force
field parameter was used to alleviate steric clashes. The
receptor grid was generated using Glide 5.8 (Maestro
Schrödinger, LLC, New York, NY, 2018) with default
settings for all parameters. An approximately large grid
size was preferred to include all active site residues
involved in substrate binding. The glide extra-standard
precision (XP) mode was used for docking of the gener-
ated receptor grid file along with all prepared ligand
conformers. Default settings were retained for the scor-
ing and refinement.
activity is shown in a Figure 2.
4
4
| COMPUTATIONAL STUDY
.1 | Molecular docking
The potential binding mode and the binding interaction
of the ligand with P. falciparum dihydrofolate reductase
thymidylate synthase PFDHFR-TS have been investigated
by using Maestro 11.0 Schrödinger, LLC, New York, NY,
018. The 3D structures of all the compounds were gener-
ated via using Marvin suites and saved as SDF file. The
D crystal structures of PFDHFR-TS from malarial (PDB
2
3
ID: 3JSU, 4DP3, 1J3K) were retrieved from the protein
data bank (www.rcsb.org). The protein was selected on
the basis of structural similarity of ligands, resolution,
and expression system. Moreover, the selected protein
4.2 | ADME-Tox study
(
pf-strain) is encouraging us to do the docking in the
A set of ADME-Tox-related properties of the synthesized
compounds were predicted by using a Qikpro program
active site for the better understanding of interaction.
The ligands with the lowest energy, correct Lewis struc-
ture, tautomers, and ionization states (pH 7.0 ± 2.0) for
each of the ligands were generated and optimized with
default settings and were prepared for molecular
[
34]
(Schrödinger, LLC, New York, NY, 2018).
LigPrep
module was used to prepare the compounds and utilized
for the calculation of pharmacokinetic parameters by
Qikpro module. The program Qikpro generates physically
FIGURE 2 Graphical presentation of biological activity

8
PATEL ET AL.
relevant descriptors and uses them to perform ADME-Tox
predictions and utilizes the method of Jorgensen to calcu-
late pharmacokinetic properties and descriptors.
4.4 | Pharmacophore model
4.4.1 | Dataset pool
A pool of 19 molecules dataset were prepared in LigPrep
module, the addition of hydrogen and generation of con-
4
.3 | Molecular dynamics
H
formers at 7.0 P using OPLS 2005 force field (LigPrep,
[
34]
The natural dynamics on different timescales of a docked
complex of compound 7e and protein (PDB: 3JSU) and
the thermal average of the molecular properties of the
complex are carried with the help of molecular dynamics
Schrödinger, LLC, New York, NY, 2018).
Phase mod-
ule implemented in the Maestro 11.0 software package
(Schrodinger, LLC) was used to generate pharmacophore
models.
(
MD) stimulation. MD simulations have been conducted
[35,36]
by Desmond program,
Materials Science Suite 2015-4.
as implemented Schrödinger
[34]
OPLS_2005 force field
4.4.2 | Pharmacophore modeling and
validation
with NPT ensemble class have been used, while pressure
and temperature were set to 1.0325 bar and 300 K,
respectively. The system was modeled by placing one 7e
molecule into the cubic box with around 3000 water mol-
ecules, and the simulation time was set to 10 ns, cut-off
radius was set to 12 Å, pressure was set to 1.0325 bars,
and the temperature was set to 300 K. In all cases when
Desmond was used, input and output files were manipu-
lated by Maestro graphical user interface application of
Schrödinger Materials Science Suite 2018.
For alignment, the compounds from the dataset were
docked into the active site pocket of the crystal struc-
ture of 3JSU, 4DP3, and 1J3K. Phase module was used
for the pharmacophore generation (Phase, version 3.3,
Schrödinger, LLC, New York, NY, 2018). The dataset
compounds were divided as low, moderate, and high
actives. Low active molecules were selected as inactive
groups, and highly active compounds were selected
TABLE 1 Microwave-assisted
synthesis of quinoline hybrid
MWI
a
Entry
Product Code
R
Time, min
Yield, %
70
thiosemicarbazide derivatives (7a-7s)
1
2
3
4
5
6
7
8
9
7a
7b
7c
7d
7e
7f
4-NO
2
C
6
H
5
3
5
5
8
5
8
5
5
5
5
5
5
5
5
5
8
3
5
5
4-ClC
4-CH
6
H
5
83
3
C
6
H
5
76
Isopropyl
3,4-diClC
t-butyl
70
6
H
4
75
72
7g
7h
7i
CH
4-OCH
4-IC
3,5-diClC
2
C
6
H
5
80
3
C
6
H
5
81
6
H
5
76
10
11
12
13
14
15
16
17
18
19
7j
6
H
4
76
7k
7l
2-OCH
3-OCH
3
3
C
C
6
6
H
5
70
H
5
82
7m
7n
7o
7p
7q
7r
7s
3,4,5-triClC
2,4-diClC
6
H
2
80
6
H
4
74
2,4-diFC
Ethyl
6
H
4
83
79
C
C
6
6
H
5
78
H
11
74
H
78
a
Purified yield.

PATEL ET AL.
9
SCHEME 2 Proposed reaction mechanism
as active groups. For pharmacophore sites, a default
feature was selected with acceptor (A), donor (D),
hydrophobic (H), negative (N), positive (P), and aro-
matic ring (R). This feature was used in the clustering
and rescoring of the models. The parameters include
83% to 70% yields with high purity within 3 to 8 minutes at
the 300-W microwave irradiation. Aliphatic substitution 7d,
7f, and 7p (Table 1, entries 4, 6, and 16) were obtained in
the lower yield, and 7b, 7c, 7h, and 7q (Table 1, entries 2, 3,
8, and 17) were obtained in the higher yield. The structures
of novel synthesized compounds were confirmed by FTIR,
H NMR, and ESI-MS and elemental analysis. We have also
proposed a mechanism for the novel synthesized deriva-
tives, which is shown in Scheme 2.
(
a) survival score, which measures the quality of align-
ment of the particular pharmacophore model, and
ii) site score is an indication of how closely the site
1
(
points are superimposed in an alignment to the
pharmacophore of the structures that contribute to the
hypothesis.
The formation of final molecules of the IR spectrum
showed a strong band at a range of 1700, 1600, and
1
3
400 cm− represented the presence of carbonyl, C C,
1
and NH groups in the molecules, respectively. H
NMR spectrum showed two peaks at a range of 11 to
5
| RESULTS AND DISCUSSION
10 ppm, indicating the 2 hydrogen of NH group of
The reaction sequences employed for the synthesis of the
title compounds (7a-7s) are shown in Scheme 1. Ethyl
thiosemicarbazide, and a multi-plate peak at a range of
2 to 3 ppm, indicating the 6 hydrogen of two methyl
groups of substituted quinoline.
2
,4-dimethylquinoline-3-carboxylate (3) is readily pre-
pared according to previously reported methods, in
which cyclization occurred by the ethyl acetoacetate, α-
amino acetophenone in ethanol under the microwave
5.1 | Biology
ꢀ
irradiation (MWI) at 300 W (130 C), and the key inter-
4
mediate N -alkyl and aryl thiosemicarbazides (6a-6s)
5.1.1 | In-vitro antibacterial and
were synthesized also prepared according to previously
reported method [A], in which hydrazine hydrate was
added in to various isothiocyanates in the ethanol under
the microwave irradiation (MWI) at 300 W. The
final novel derivatives of substituted quinolines (7a-7s)
were synthesized in presence of glacial acetic acid
under the microwave irradiation at 300 W. Finally,
targeted compounds, 2-(2,4-dimethylquinoline-3-carbonyl)-
N-substituted hydrazinecarbothioamide were obtained in
antifungal activity
Reviewing the biological activities of quinoline hybrid
thiosemicarbazide derivatives indicates all the scaffolds
were found to be highly potent to moderate activity
against the specific strains. Table 2 shows that bioassay
results of a series of 7a-7s compounds relevant that com-
pound 7a (MIC 50 μg/mL) containing nitro group at
4-position of phenyl ring was found to be the most potent

10
PATEL ET AL.
against the P. aeruginosa as compared with chloram-
phenicol (MIC 50 μg/mL) as a standard drug, while com-
pounds 7g and 7k (62.5 μg/mL) exhibited more potent
activity against the P. aeruginosa. However, compounds
(Table 2, entries 4, 6, and 16). Chloro-substituted group
on phenyl ring compounds 7e, 7j (100 μg/mL) and 7b,
7m (MIC 250 μg/mL) display excellent activity on the
same strain, and compound 7o (250 μg/mL) containing
fluoro group at 2-position and 4-position of the phenyl
ring was found to be the most active compound against
the P. aeruginosa compared with chloramphenicol and
7
d, 7f (MIC 125 μg/mL), and 7p (MIC 100 μg/mL), hav-
ing aliphatic linker, show the minimum inhibition con-
centration with the lowest value in P. aeruginosa strain
TABLE 2 In vitro biological activity of title compounds 7a-7s
Antibacterial
a
b
c
d
e
Gram-Negative Organism
Gram-Positive Organism
Antifungal
Ca An
Antimalaria AntiTB
Entry Pro. Code Ec
Pa
50
Sa
Sp
Ac
Pf
H37RV
250
25
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
7a
7b
7c
7d
7e
7f
25
100
100
62.5
125
500
500
500
250
500
100
250
125
250
125
62.5
250
125
125
250
250
50
62.5
62.5
125
200
250
250
250
125
250
250
500
250
250
125
100
125
125
100
250
100
50
500 500
500 250
250 250
1000
250
250
0.25
0.15
0.02
125
62.5
100
250
50
250
100
125
100
125
62.5
100
125
100
62.5
125
250
100
250
250
250
250
500
—
500
100
250
125
100
50
1000 >1000 >1000 0.54
500 250
500 1000
1000 1000
250 500
1000 500
250 250
500 1000
500
0.19
0.26
0.54
1.22
1.52
0.36
1000
1000
500
7g
7h
7i
100
25
62.5
125
100
100
250
62.5
125
250
500
25
1000
500
500
250
500
100
50
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
7j
7k
7l
>1000 1.98
1000 >1000 >1000 0.10
7m
7n
7o
7p
7q
7r
500 250
500 1000
500 500
1000 500
250 500
250
0.43
1.23
0.25
0.15
0.02
1000
1000
1000
1000
25
125
62.5
100
250
500
—
1000 >1000 >1000 0.54
7s
500
100
50
250 500
500
—
0.19
—
f
Amp
—
—
—
—
—
—
f
Cam
50
—
—
—
f
Cipro
25
25
50
50
—
—
—
f
Ny
—
—
—
—
100 100
500 100
100
100
—
—
—
f
Gris
—
—
—
—
—
—
f
INH
—
—
—
—
—
—
—
—
—
—
—
—
—
0.20
1.00
—
f
RMP
—
—
—
—
—
—
f
Quin
—
—
—
—
—
0.26
0.02
f
CQ
—
—
—
—
—
—
Note: —, not tested.
a
Values expressed in μg/mL, Escherichia coli MTCC 443 (Ec), Pseudomonas aeruginosa MTCC 1688 (Pa).
Values expressed in μg/mL, Staphylococcus aureus MTCC 96 (Sa), Streptococcus pyogenes MTCC 442 (Sp).
b
c
Values expressed in μg/mL, Candida albicans MTCC 227 (Ca), Aspergillus niger MTCC 282 (An), Aspergillus clavatus MTCC 1323 (Ac).
d
Values expressed in IC50 μg/mL, Plasmodium falciparum.
e
Values expressed in MIC μg/mL, H37RV strain.
f
Standard drug (Ampicillin, Chloramphenicol, Ciprofloxacin, Nystatin, Griseofulvin, Isoniazid, Rifampicin, Quinine, Chloroquine).

PATEL ET AL.
11
ciprofloxacin as standard drug. Compounds 7a, 7h (MIC
exhibited moderate activity against the bacterial and
fungal strains.
2
5 μg/mL) at fourth substitution at phenyl ring and 7r
MIC 25 μg/mL) with a cyclo group having excellent
activity against the E. coli compared with ciprofloxacin
MIC 25 μg/mL). Compound 7f (MIC 50 μg/mL), hav-
(
(
5.1.2 | In-vitro antimalarial and
ing aliphatic linkage (t-butyl group), has good potency
against the E. coli as compared with chloramphenicol
antituberculosis activity
(
7
MIC 50 μg/mL) as standard drug. Here, compounds
c, 7i, and 7n (MIC 62.5 μg/mL) exhibited high activ-
The antimalarial activity was performed against
P. falciparum strain by the reported method (see Supporting
Information). Results show that compounds 7a, 7b, 7c, 7e,
7f, 7l, 7o, 7p, 7q, and 7s exhibited higher potency activity
against the P. falciparum strain. Compound 7a (0.25 μg/
mL) having a nitro group at 4-position on phenyl, 7f
(0.25 μg/mL) having t-butyl linkage, and 7o (0.26 μg/mL)
having fluorine at 2,4-position phenyl exhibited excellent
activity against the P. falciparum as compared with quinine
(0.26 μg/mL). Compound 7b (0.15 μg/mL) containing chlo-
rine at 4-position and 7p (0.15 μg/mL) containing aliphatic
linkage exhibited excellent activity as compared with qui-
nine. Compound 7c (0.02 μg/mL) containing methyl group
at 4-position on phenyl and 7q (0.02 μg/mL) having cyclo
phenyl group shows higher activity than other compounds
ity against the E. coli as compared with ampicillin as
standard drug. Compound 7c (MIC 62.5 μg/mL) hav-
ing a methyl group at 4-position and 7o (MIC 62.5 μg/
mL) having fluorine group shows high potency against
the S. aureus. Compounds 7a, 7b, and 7j (MIC 100 μg/
mL) have good potency against the S. aureus as com-
pared with ampicillin (250 μg/mL) standard drug.
Compounds 7c, 7h, 7j, 7q, and 7s (MIC 250 μg/mL)
show good activity against the C. albicans, compounds
7
b, 7c, 7e, 7j, and 7m (MIC 250 μg/mL) show good
activity against A. niger, and compounds 7b, 7c, and
m (MIC 250 μg/mL) shows good activity against the
7
A. clavatus. Moreover, other remaining compounds
TABLE 3 XP Glide score for compounds 7a-7s with PFDHFR-TS
PDB:3JSU
PDB:4DP3
PDB:1J3K
Entry
Product Code
XP GScore
−7.008
−8.38
XP HBond
−0.194
−1.33
−0.649
0
XP GScore
−6.114
−5.828
−7.239
−6.245
−6.488
−5.432
−6.234
−6.642
−6.044
−5.978
−6.473
−5.822
−6.225
−6.285
−6.508
−5.444
−6.965
−4.609
−5.236
−6.273
−6.675
XP HBond
−0.448
−0.84
−0.746
−0.645
−0.343
−0.659
−0.57
−0.465
−0.879
0
XP GScore
−2.048
−4.323
−3.324
−3.521
−3.892
−3.696
−3.403
−3.874
−3.035
−2.546
−2.225
−3.039
−3.48
XP HBond
0
1
2
3
4
5
6
7
8
9
7a
7b
−0.29
−0.368
−0.7
7c
−8.292
−6.77
7d
7e
−9.592
−7.381
−7.938
−8.188
−8.823
−7.365
−7.669
−6.12
−0.368
−0.002
−1.27
−0.622
0
−0.7
7f
−0.376
−0.53
−0.576
−0.7
7 g
7h
7i
10
11
12
13
14
15
16
17
18
19
20
21
7j
−1.627
−0.225
−0.814
−0.453
0
0
7 k
7l
0
−0.448
−0.994
0
0
7 m
7n
7o
−5.894
−8.649
−8.375
−5.38
−0.281
−0.295
−0.817
−0.123
−0.971
−0.418
−0.04
−0.7
−3.236
−3.549
−3.038
−1.987
−2.537
−3.963
−3.907
−3.781
−0.782
−0.15
−0.796
−0.992
−0.7
−0.7
7p
7q
−0.468
−0.556
−1.007
−0.759
−0.645
0
−8.453
−8.331
−6.628
−4.899
−5.568
7r
7s
−0.369
0
Quin*
CQ*
−0.9
0

12
PATEL ET AL.
as compared with standard drugs quinine (0.26 μg/mL) and
chloroquine (0.02 μg/mL). Compounds 7e (0.19 μg/mL), 7l
7b and 7n having chlorine group at 4-position and 2, 4
di chloro group on the phenyl ring exhibited excellent
activity against the H37RV strain with MIC value
25 μg/mL. Compound 7h has the methoxy group at
4-position on phenyl ring, and compound 7m having
chlorine group shows potent activity against the
same strain with MIC 50 μg/mL. In addition, other
remaining molecules did not produce significant
(0.10 μg/mL), and 7s (0.19 μg/mL) show good activity com-
pared with quinine as a standard drug. Other remaining
compounds also show a moderated activity with reference
to standard drugs. The anti Mycobacterium tuberculosis
activity performed against the H37RV strain by the
broth dilution method. Results show that compounds
FIGURE 3 A, Binding mode of
7b and 7i into active site of 3JSU. B,
Binding mode of 7c and 7l into active
site of 4DP3

PATEL ET AL.
13
results with respect to standard drugs. Compounds 7b
and 7n show moderate activity against the first-line
drugs isoniazid and rifampicin. The results are sum-
marized in Table 2.
one molecule (7g) of title compound could closely fit into
the active site of 4DP3, and three molecules (7c, 7l, and
7p) of substituted derivatives of quinoline compounds
could closely fit into the active site of 4DP3 and coordi-
nate very similar to the native ligand in the crystal struc-
ture; two molecules (7b and 7l) were found to be closely
bound into the active site of 1J3K. A complex of
PFDHFR-TS was stabilized by the formation of signifi-
cant closely bound with bonding and nonbonding, vari-
ous interaction through active site of amino acid and
other interaction also observe with reference ligand to
the standard inhibitors.
The binding energy of all molecules was found in the
negative, which signifies the energy required for the for-
mation of interaction with the active site of complex. The
lower the value of binding energy, the stronger is the
affinity towards the active site. As per the docking analy-
sis, the docking energy of PDB: 3JSU was found between
−5.38 and −9.59 kcal/mol; for PDB: 4DP3, between −4.60
and −7.23 kcal/mol; and for PDB: 1J3K, between −1.98
and −3.54 kcal/mol. In these cases, compounds 7b and
7i; compounds 7c and 7l; and compounds 7b and 7l have
shown the least binding energy with the protein PDB:
3JSU, 4DP3, and 1J3K, respectively. From Table 3, we
5
.2 | Computational study
.2.1 | Docking study
5
Molecular docking is a structure-based drug design that
became an important part of drug discovery telling the
knowledge of binding sites, binding energy, affinities,
and thermodynamic properties of protein-ligand com-
plexes. Therefore, with the aim of promising active drug
molecules from the current biological activity of all titled
compounds, we investigated the molecular basis of their
interaction, and a molecular docking study against
PFDHFR-TS on 3JSU, 4DP3, and 1J3K were carried out
using Glide-based Ligand Docking with Energetics on
Glide program of Schrodinger molecular modeling suite.
From the docking study, it is clear that four molecules
(
7b, 7e, 7i, and 7q) of substituted derivatives of quinoline
compounds could closely fit into the active site of 3JSU,
FIGURE 4 (a), Superimposition of pharmacophore generation. (b), The pharmacophore model hypothesis of DHHRR. (c),
Pharmacophore model of DHHRR aligned with the highest active compound in the dataset. (d), Superimposition of various hypothesis

14
PATEL ET AL.
have found potent molecules with respect to biological
activity. which lead to the further study of such com-
pounds 7b (−8.32) and 7i (−8.22) in PDB: 3JSU, com-
pounds 7c (−7.23) and 7l (−5.82) in PDB: 4DP3, and
compounds 7b (−4.323) and 7l (−3.039) in PDB: 1J3K.
Compounds 7b and 7i are found to be stabilized with
active site through Van der Waals interactions with LEU
interacted in hydrogen bond with the active site of resi-
dues. The compounds 7b exhibited hydrogen bonding
between NH of the thiosemicarbazide linkage and
o
residue SER 111 with the bond length 2.0 A and 7i
exhibited hydrogen bonding between NH of the
thiosemicarbazide linkage and residue TYR 170, LEU
o
o
164 with the bond length 2.3 A , 2.6 A . A very important
π- π interaction also found between substituted aromatic
ring (compound 7i) and PHE 58 residue in the active site.
The compounds 7c and 7l exhibited hydrogen bonding
between the oxygen atom of linkage and hydrogen atom
of amino acid GLY 457 and GLN 118, respectively, with
1
64, PHE 116, PRO113, VAN 45, LEU 46, ASN 42, and
SER 111 residue and interaction with ASN 108, SER
11, LEU 45, TYR 170, LEU 164, and ASH 54 residue
1
through the nucleus (Figure 3a). Compounds 7c and 7l
are bound to be stabilized with active site through Van
der Waals interaction with GLY 457, ASP 435, GLY
o
o
the bound length with 2.3 A , 2.1 A . And π- π interac-
tion was found between quinoline ring (compound 7l)
and GLU 122 residue in the active site. Electrostatics
and other interaction of compounds are described in
4
1
34, LYS 458, and ASP 510 and ASP 80, ARG 119, ALA
17, GLN 118, and ASP 80 through the nucleus
(Figure 3b). Furthermore, each of the molecules was
TABLE 4 Predicted ADME-Tox parameter for the title compounds 7a-7s
Percent Human
Product Code
Oral Absorption
85.871
100
QPPCaco
163.789
1369.894
1369.328
1264.592
1369.234
1369.234
1404.59
1476.362
1368.702
1370.393
1369.134
1854.969
1367.189
1369.031
1839.495
1692.196
1259.928
1370.052
1379.78
516.801
821.804
1436.68
277.474
22.644
QPlogBB
−1.557
−0.273
−0.454
−0.514
−0.144
−0.144
−0.438
−0.481
−0.512
−0.253
−0.117
−0.347
−0.513
−0.016
0.032
QplogKhsa
0.437
0.581
0.621
0.275
0.683
0.683
0.447
0.59
QPlogHERG
−6.469
−6.47
QPlogS
−6.092
−6.636
−6.46
PSA
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
a
b
c
d
e
f
122.152
77.235
77.232
77.876
77.238
77.238
75.405
77.065
85.525
77.235
77.242
82.753
85.478
77.245
76.159
76.665
78.181
77.233
77.084
92.489
42.892
26.062
81.354
93.3
100
−6.465
−5.499
−6.378
−6.378
−5.615
−6.831
−6.444
−6.53
100
−5.038
−7.238
−7.238
−5.831
−6.426
−6.147
−6.876
−7.361
−5.957
−6.07
100
100
g
h
i
100
100
100
0.488
0.629
0.692
0.483
0.486
0.785
0.679
0.543
0.172
0.471
0.592
−0.136
0.243
0.597
−0.752
−0.059
−0.171
j
100
k
l
100
−6.372
−6.36
100
m
n
o
p
q
r
100
−6.41
100
−6.282
−6.25
−7.832
−7.122
−6.395
−4.864
−5.91
100
100
−0.127
−0.426
−0.428
−0.449
−0.606
0.211
−6.219
−5.3
100
100
−6.56
s
100
−5.638
−4.632
−5.45
−6.222
−3.701
−3.3
a
86.134
100
Quin*
CQ*
INH*
Cipro*
NRFX*
100
0.397
−6.415
−3.592
−2.953
−2.991
−4.641
−0.052
−3.772
−3.446
66.893
52.666
47.412
−0.842
−0.389
−0.5
20.376
93.483
Note: %, human oral absorption in GI (±20%). QPPCaco, Apparent Caco-2 permeability (nm/s) (500 great); QPlogHERG, HERG K + channel blockage
concern below −5); QPlogP, octanol/water (−2.0, − 6.5); QPlogS, Predicted aqueous solubility, (−6.5, − 0.5).
(

PATEL ET AL.
15
Figure 3. Such hydrogen bonding and π- π stacking
interactions are very crucial as they serve as an
activity, molecules were divided into three groups: low,
moderate, and high activity. High active groups were
selected as representative of a common pharmacophore
generation. Default interaction features such as acceptor
(A), donor (D), hydrophobic (H), positive ionisable (P),
negative ionisable (N), and ring aromatic (R) were used
for generating favorable pharmacophore models. In addi-
tion, three common features, DHHRR, AHHRR, and
AHHPR, were selected for the pharmacophore genera-
tion (Figure 4). In summary, the common five-feature
model DHHRR was selected for the best pharmacophore
generation. For the DHHRR model, a total of 13 actives
in the dataset and 12 actives were recovered in the
dataset to 93% to active recovered. Other model AHHRR
and AHHPR show similar results with 60% and 79%
“
anchor” guiding the 3D orientation of the ligand in its
active site and also facilitate the steric and electrostatic
interactions adding to the stability of the enzyme-
inhibitor complex. Figure 3a,b showed the binding
mode of compounds 7b, 7i, and compounds 7c, 7l,
respectively; other binding mode of compounds are
shown in Supporting Information.
5.2.2 | Pharmacophore model
A feature of pharmacophore model was used to identify
the important interaction with proteins. On the basis of
FIGURE 5 Simulation interaction with ligand (7e). (a), Ligand interaction properties. (b), Ligand torsions. (c), Ligand protein contacts
in 2D. (d), Ligand protein RMSF. (e), Protein ligand interaction. (f), Protein ligand RMSD. (g), Protein RMSF

16
PATEL ET AL.
FIGURE 5 (Continued)
active recoverability performance. Here, the survival
score of DHHRR, AHHRR, and AHHPR are 6.308,
descriptors of Qikpro such as Polar surface area (PSA)
(70-200 Å) as the oral bioavailability, percent human
oral absorption (80% to 25%), Caco-2 cell permeability
(QPPCaco) as model for gut-blood barrier (25 to 500),
QPlogkhsa as human serum albumin binding (−1.5 to
1.5), QPlogBB as blood/brain partition coefficient (−3.0
to −1.5), QPlogS as aqueous solubility parameter (−6.5
to 5), and QPlogHERG (below −5) are described in
Table 4. Analog 7f, 7j, and 7o found to be in good bio-
avaibility with described range.
6
.097, and 6.023, respectively. Moreover, AHRR shows a
poor performance with 1.361 survival score. As per these
results, we continue our research with the pharmacophore
modeling with our knowledge.
5.2.3 | ADME-Tox study
The title molecules (7a-7s) were evaluated for their in sil-
ico pharmacokinetics properties leading to drug-likeness
using Qikpro (Schrödinger, LLC, New York, NY, 2018).
The Jorgensen method was utilized by the program
Qikpro for the pharmacokinetics properties and descrip-
5.2.4 | Molecular dynamics
In these studies, a behavior and simulation of best
docked compound 7e with PDB: 3JSU were investigated
by using molecular dynamics simulation. Compound 7e
was formed open catalytic activity with A: Leucine 40, A:
Serine 111, A: Leucine 164, A: Tyrosine 170, A: Glycine 44,
[37]
tors.
It can give a very good idea about which com-
[
38]
pounds deserved further attention for evaluation.
The
compute ADME-Tox parameters along with their
acceptable limits are as indicated in Table 4. Various

PATEL ET AL.
17
A: Asparagine 108. The various energy, ligand properties,
hydrogen bond, and Van der Waals force have been noti-
fied with various levels in the study. According to the
interaction and forces, compound 7e fluctuated at some
Gujarat, India for financial support (Project: MRP
No. GUJCOST/MRP/2017-18/2323).
CONFLICT OF INTEREST
The authors declare no potential conflict of interest.
o
levels yielding an RMSD value of 2.2 A . Figure 5 showed
that protein and ligand were similarly fluctuated in the
o
system with a range of 0.3 to 2.4 A . Figure 5 showed
protein-ligand π-π interaction with Phenylalanine 58 and
ALA 16, VAL 45, LEU 46, TRP 48, CYS 50, MET 55, THR
ORCID
Hitesh D. Patel https://orcid.org/0000-0002-0664-8874
1
1
07, ASN 108, ILE 112, PRO 113, PHE 116, LEU 119, LEU
64, SER 167 amino acids formed various interactions in
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How to cite this article: Patel DB, Darji DG,
Patel KR, Rajani DP, Rajani SD, Patel HD.
Synthesis of novel quinoline-thiosemicarbazide
hybrids and evaluation of their biological activities,
molecular docking, molecular dynamics,
pharmacophore model studies, and ADME-Tox
properties. J Heterocyclic Chem. 2020;1–18. https://
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Chem 2019, 56, 539–51.
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D. P. Rajani, S. D. Rajani, N. S. Shah, D. D. Zala, H. D. Patel,
J Heterocycl Chem 2019, 58, 00.
[