Derivatives of 4,5-dihydro (1H) pyrazoles as possible MAO-A inhibitors in depression and anxiety disorders: synthesis, biological evaluation and molecular modeling studies

Article abstract of DOI:10.1007/s00044-018-2167-z

A series of 1,3,5-trisubstituted-2-pyrazoline derivatives (3a–3t) were synthesized in appreciable yields by substituting N1 position of 2-pyrazoline nucleus with 4-nitrobenzenesulfonylchloride using conventional and microwave assisted synthetic approaches

Full text of DOI:10.1007/s00044-018-2167-z

MEDICINAL
CHEMISTRY
RESEARCH
Medicinal Chemistry Research
https://doi.org/10.1007/s00044-018-2167-z
ORIGINAL RESEARCH
Derivatives of 4,5-dihydro (1H) pyrazoles as possible MAO-A
inhibitors in depression and anxiety disorders: synthesis, biological
evaluation and molecular modeling studies
Avinash C. Tripathi1 Savita Upadhyay1 Sarvesh Paliwal2 Shailendra K. Saraf2
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●
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Received: 20 January 2018 / Accepted: 9 March 2018
© Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
A series of 1,3,5-trisubstituted-2-pyrazoline derivatives (3a–3t) were synthesized in appreciable yields by substituting N1
position of 2-pyrazoline nucleus with 4-nitrobenzenesulfonylchloride using conventional and microwave assisted synthetic
1
approaches. The physicochemical and spectral characterization such as IR, Mass, H-NMR and 13C-NMR, and elemental
analysis, assured the formation of proposed derivatives. Pharmacological studies revealed that compound 3d exhibited
highest antidepressant activity however, compound 3l was found to be most effective anxiolytic agent at the tested doses (50
and 100 mg/kg b.w.), when compared to the control group. Molecular docking simulations established the possible
mechanism of their neuropharmacological effects, with admirable affinity towards MAO-A protein. This was also evidenced
from some of the key interactions of these compounds with the amino acid residues Ala68, Tyr69, Phe208, Tyr407 and
Tyr444. Moreover, synthesized derivatives showed encouraging pharmacokinetic (ADME) and toxicological (neurotoxicity,
carcinogenicity, mutagenicity, reproductive toxicity, irritancy and acute toxicity) parameters as predicted by computational
programs. Some of these toxicity studies were further examined in wet laboratory by accomplishing behavioral neurotoxicity
studies and acute toxicity studies as per OECD guidelines.
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Key words 2-Pyrazoline Anxiolytic Antidepressant Locomotor and neuromuscular coordination studies Glide docking
FST and TST
Introduction
first generation antidepressants used for decades to treat the
patients suffering from high level of anxiety, atypical
depression (Pletscher 1991), anergic bipolar depression and
treatment resistant depression (Thase 2012), specific pho-
bias, post-traumatic stress disorder and migraine headaches
resistant to other therapies (Gareri et al. 2000). The MAO-A
inhibitors are employed in the treatment of certain mental
disorders such as depression and anxiety (Amrein et al.
1999). However, MAO-B inhibitors have proven their
corrective value in neurodegenerative diseases (Foley et al.
2000; Youdim et al. 2006) such as Parkinson’s (Cesura and
Pletscher 1992) and Alzheimer’s (Volz and Gleiter 1998).
The initial hydrazine class of MAO inhibitors was asso-
ciated with some severe adverse effects, such as liver
toxicity and cheese reaction (Brown et al. 1989). These
side-effects were correlated to nonselective and irreversible
MAO inhibition. Pyrazoline derivatives have attracted
substantial attention for years, chiefly 1,3,5-trisubstituted-2-
pyrazoline pharmacophore has been associated with
encouraging neurological activities such as tranquilizer,
anticonvulsant, and antidepressant (Kaplancikli et al. 2010;
In the nervous system, the monoaminergic homeostasis and
neurotransmission is regulated by monoamine oxidases
(MAOs). Low level of certain neurotransmitters (NTs) in
the brain, like-dopamine (DA), norepinephrine, serotonin
(5-HT), and gamma amino butyric acid, is the main cause of
depressive mental disorders. The concentration of NTs in
the brain is increased by blocking the action of MOAs
through monoamine oxidase inhibitors (MAOIs) (Meyer
et al. 2006; Mitoma and Ito 1992). MAOIs belong to the
* Shailendra K. Saraf
dirpharmniec@gmail.com
1
Division of Pharmaceutical Chemistry, Faculty of Pharmacy, Babu
Banarasi Das Northern India Institute of Technology, Lucknow,
U.P. 226028, India
2
Professor and Head, Department of Pharmacy, Banasthali
Vidyapith, Banasthali, Tonk, Rajasthan 304022, India

Medicinal Chemistry Research
Ozdemir et al. 2008; Palaska et al. 2001; Prasad et al. 2005;
Ruhoglu et al. 2005), psychoanaleptic, MAO inhibitory and
other biological activities (Chimenti et al. 2004, 2010;
Gokhan-Kelekci et al. 2009; Gokhan et al. 2003; Jagrat
et al. 2011; Jayaprakash et al. 2008; Karuppasamy et al.
2010; Maccioni et al. 2010; Manna et al. 2002; Mishra and
Sasmal 2011; Sahoo et al. 2010; Tripathi et al. 2018a). The
above findings prompted research to develop selective and
reversible type of MAO (A and B) inhibitors. Considering
these facts, some 1,3,5-trisubstituted-2-pyrazolines were
synthesized by effecting some novel aromatic and hetero-
aromatic substitutions at 3rd and 5th positions, respectively.
Microwave facilitated synthetic technique was also utilized
to prepare the proposed compounds and the results were
compared to those of the conventional heating methods
(Lidstrom et al. 2001). This work is in continuation to the
previous study by our group (Tripathi et al. 2016; Tripathi
et al. 2018b; Upadhyay et al. 2017a, b), with some novel
derivatives having promising potential in the field.
green chemistry approach of microwave assisted organic
synthesis (MAOS) as given in Fig. 1. The MAOS showed
better synthetic efficiency when compared with the con-
ventional procedures. The synthesized derivatives were
characterized by various physicochemical (Table 1) and
spectral techniques. The spectral analysis data expounded
C=N stretching (1509–1612 cm−1), N–H stretching
(3456–3105 cm−1) and C–H deformation (1428–1357 cm
−1) along with a characteristic peak of sulfonyl group
absorption bands (1340–1180 cm−1) in the corresponding
regions of IR spectra.
Detailed
SAR
studies
revealed
that
4-
nitrobenzenesulfonyl substitution at N1 position of 2-
pyrazoline nucleus was crucial in exhibiting good anti-
depressant and anti-anxiety activities. It was also observed
that a polar, 4-hydroxyphenyl, substitution at 3rd position
and thiophen-2-yl substitution at 5th position of 2-
pyrazoline nucleus was instrumental for the remarkable
antidepressant potency of compound 3d. However, when
the polar 4-hydroxyphenyl substituent of the same phar-
macophore was replaced by a bulky hydrophobic 1-
naphthyl substituent, the spectrum of activity shifted
towards anxiolytic, as shown by compound 3l (Fig. 2). The
biological activities of the synthesized compounds were
Results and discussion
Synthesis of a series of fourteen 2-pyrazoline derivatives
(3a–3t) was undertaken using conventional as well as a
Conventional Method
Fig. 1 Synthesis of 1,3,5-
trisubstituted-2-pyrazoline
derivatives
O
0-10 oC, Stir, 24-48 hrs.
H
C
CH3
O
R
C
H
R'
R-CHO
C2H5OH, KOH
+
R'
MWI: 120-280W, 40-190s
Chalcone derivatives
(1a-1t)
MAOS
Aldehyde
Ketone
Conventional Method
Reflux, 3-6 hrs.
R
R'
N NH
NH2NH2.H2O
3,5-Disubstituted
2-pyrazoline derivatives
(2a-2t)
MWI: 240-350W, 50-250s
MAOS
R
O
Conventional Method
Stir, 1-3 hrs.
N
S
NO2
N
4-Nitrobenzenesulfonyl chloride
O
R'
1,3,5-Trisubstituted
2-pyrazoline derivatives
(3a-3t)
MWI: 210-350W, 145-210s
MAOS
OCH3
S
O
Cl
Where R:
OCH3
and R':
OH
Cl
N

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Fig. 2 a Graph showing antidepressant activity (Forced Swim Test); b
Graph showing antidepressant activity (Tail Suspension Test); c Graph
showing anti-anxiety activity (number of entries in closed arms in
Elevated Plus Maze Test); d Graph showing anxiety activity (time
spent in closed arms in Elevated Plus Maze Test)
dependent upon the doses administered, with increased
effects at higher tested dose (100 mg/kg b.w.).
imperative targets to develop potential neuropharmacolo-
gical agents. Docking studies also confirmed that the pre-
sence of sulfonyl group at N1 position of pyrazoline nucleus
established a hydrogen bonding interaction between the
sulfonyl oxygen of the ligands and hydroxyl hydrogen of
either Tyr69 or Ala68 side chain residues. Due to these
Hydrogen bonding interactions, substituted phenyl ring at
C5 and benzenesulfonyl ring at N1 position of pyrazoline
nucleus were well placed in the aromatic cage. The most
potent compound from N1 benzenesulfonyl substituted
series (3d, 3l) displayed additional key interactions of this
moiety with side chain and backbone residues of the amino
acids at the binding pocket. This included- a hydrophobic
interaction of thiophene and 4-hydoxyphenyl rings with Tyr
407, Tyr444 residues, and H-bond interactions of 4-nitro
and 4-hydroxyphenyl groups with the Gly443, Phe208 and
Arg51 binding site residues (Figs. 3 and 4). Also, favorable
in silico ADME performances (Table 3) were obtained for
all the synthesized compounds. Furthermore, the tested
compounds were found to be safe, by not presenting any
potential risks of carcinogenicity, mutagenicity, reproduc-
tive toxicity, acute toxicity and irritancy as predicted by
LAZAR and OSIRIS Property Explorer programs (Table 4).
Therefore, the present study clearly demonstrated the
All the synthesized derivatives were also evaluated for
their possible neurotoxicological effects, like- neuromus-
cular coordination and locomotor activities using rotarod
and actophotometer tests, respectively. It was observed that
none of the synthesized compounds showed serious neu-
rotoxicity (disturbances in the motor co-ordinations and
locomotor activity) threats at the tested doses (Table 2).
Therefore, any possibility of CNS stimulating or depressing
effects of the tested compounds was ruled out. Additionally,
two most potent derivatives (3d and 3l) were screened for
their acute toxicities, at the tested doses. During these stu-
dies; behavioral pattern, changes in skin and fur, convul-
sions, tremors and death were not observed in any of the
animals, in due course of 14 days of acute toxicity studies as
per the OECD guidelines.
The results obtained by animal experimentation were
further supported by the outcome of molecular docking
experiments. The antidepressant and anxiolytic properties of
substituted 2-pyrazoline derivatives may be attributed to
their MAO-A inhibiting capabilities. The synthesized
compounds were found to possess a strong affinity towards
MAO-A enzyme, and may therefore be deemed as

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expediency of synthesized 2-pyrazoline derivatives in neu-
ropharmacological disorders.
Materials and methods
The chemicals and reagents were procured from Sigma
Aldrich and S. D. Fine Chemicals, Mumbai, India and pre-
coated thin layer chromatography (TLC) sheets were pur-
chased from Merck Chemicals, India and were used as such.
Solvents were of reagent grade and were purified and dried
by standard procedures. Microwave assisted synthesis was
performed using Raga’s Scientific Microwave System
(Ragatech, Pune, Maharashtra, India). Melting points were
determined by open capillary method and are uncorrected.
IR spectra were recorded on Bruker FT-IR, ALPHA-T
(Eco-ATR) spectrophotometer, (Bruker, Tech. Pvt. Ltd.,
1
USA), and the values are expressed in cm−1. H-NMR and
13C-NMR spectra were recorded on Bruker Avance-400,
FTNMR spectrometer (Bruker, Tech. Pvt. Ltd., USA) at
400 MHz and the chemical shifts are reported in parts per
million (δ value), taking TMS (δ 0 ppm for 1H NMR) as the
internal standard. Mass spectra were recorded on Waters
UPLC-TQD Mass Spectrometer instrument (Waters Cor-
poration, USA) using LC-ESI or APCI-MS Technique.
Elemental analysis was performed on Perkin Elmer-2400,
Series-II Analyzer (Waltham, Massachusetts, USA).
Chemistry
Appropriately substituted aromatic/ heteroaromatic alde-
hydes and ketones were reacted in an alkaline medium to
form the substituted chalcones (1a–1t), through Claisen-
Schmidt condensation, in the first step of the reaction. This
was followed by heterocyclization of substituted chalcones
to 2-pyrazoline derivatives (2a–2t) using hydrazine hydrate
in excess. Further, the N1 position of the 2-pyrazoline
intermediates
were
substituted
by
4-
nitrobenzenesulfonylchloride (3a–3t) in the final step of
the reaction, as given in Scheme 1. Progress of the reactions
was monitored by TLC on precoated silica gel G plates,
using iodine vapors and UV light as the visualizing agents.
General procedure for the synthesis of chalcones (1a–1t)
Conventional synthesis To a solution of different ketones
(0.01 M) and suitably substituted aldehydes (0.01 M) in
ethanol (10 mL), aqueous solution of potassium hydroxide
(60%) was added drop wise and with continuous stirring at
0 °C over a period of 15 min–2 h. The reaction mixture was
stirred at a low temperature (0–10 °C) for about 20–36 h,
with occasional shaking. After 36 h, it was poured into ice-
cold water and then neutralized to pH 2 using 6 N

Medicinal Chemistry Research
Fig. 3 Ligand receptor
interaction diagram of
compound 3d at the binding site
of MAO-A protein (PDB ID:
2Z5X) showing best
antidepressant activity. a 2D
Ligand receptor interaction
diagram. b 3D Ligand receptor
interaction diagram
General procedure for the synthesis of 3,5-disubstituted-2-
pyrazoline derivatives (2a–2t)
hydrochloric acid. The yellow colored intermediates (chal-
cones) obtained were filtered, washed, dried, and re-
crystallized from methanol (Tripathi et al. 2016; Upad-
hyay et al. 2017a, b).
Conventional synthesis Appropriate chalcone was treated
with 10 times excess of hydrazine hydrate (80%) in dry
ethanol and refluxed for 3–6 h. The hot reaction mixture
was then poured into ice-cold water. The separated out solid
was filtered, washed, dried and re-crystallized from ethanol/
acetone/ethyl acetate to afford the respective pyrazoline
(Tripathi et al. 2016; Upadhyay et al. 2017a, b).
Microwave assisted organic synthesis (MAOS) Different
aromatic/hetero-aromatic ketones (0.01 M) and suitably
substituted aldehydes (0.01 M) were reacted, in the presence
of hydro-alcoholic solution of KOH (60%, 10 mL), under
microwave irradiation (MWI: 120–280 W, 40–190 s). The
reaction mixture was poured into ice-cold water and then
neutralized to pH 2 using 6 N hydrochloric acid. The yellow
colored intermediates (chalcones) obtained were filtered,
washed, dried, and re-crystallized from methanol (Tripathi
et al. 2016; Upadhyay et al. 2017a, b).
Microwave assisted organic synthesis (MAOS) Appropriate
chalcone was treated with 10 times excess of hydrazine
hydrate (80%) in dry ethanol, under microwave irradiation
(MWI: 240–350 W; 50–250 s). The reaction mixture was

Medicinal Chemistry Research
Fig. 4 Ligand receptor
interaction diagram of
compound 3l at the binding site
of MAO-A protein (PDB ID:
2Z5X) showing best anti-anxiety
activity. a 2D Ligand receptor
interaction diagram. b 3D
Ligand receptor interaction
diagram
then poured into ice-cold water. The separated out solid was
filtered, washed, dried and re-crystallized from ethanol/
acetone/ethyl acetate to afford the respective pyrazolines
(Tripathi et al. 2016; Upadhyay et al. 2017a, b).
from acetonitrile/ methanol to obtain the pure product
(Tripathi et al. 2016; Upadhyay et al. 2017a, b).
Microwave assisted organic synthesis (MAOS) Appro-
priately substituted 3,5-disubstituted-2-pyrazolines (0.001 M)
General procedure for the synthesis of 1,3,5-trisubstituted-
were
reacted
with
4-chlorobenzenesulfonylchloride
2-pyrazoline derivatives (3a–3t)
(0.002 M) under microwave irradiation (MWI: 210–350 W;
145–210 s), taking THF (10 mL) as the solvent. After the
completion of reaction, the reaction mixture was poured in a
petri plate and the solvent was evaporated to dryness. The
crude product was re-precipitated using acetonitrile/
methanol and recrystallized from acetonitrile/ methanol to
obtain the pure product (Tripathi et al. 2016; Upadhyay
et al. 2017a, b).
Conventional synthesis Appropriately substituted 3,5-dis-
ubstituted-2-pyrazolines (0.001 M) were reacted with 4-
chlorobenzenesulfonylchloride (0.002 M) by stirring, taking
tetrahydrofuran (THF) (10 mL) as the solvent. Stirring was
continued for 1–4 h. After the completion of reaction, the
reaction mixture was poured in a petri plate and the solvent
was evaporated to dryness. The crude product was re-
precipitated using acetonitrile/ methanol and recrystallized

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Table 4 In silico toxicity prediction data of the synthesized derivatives (3a–3t)
Compounds Toxicity prediction
Osiris property explorer
LAZAR
Mutagenic
Tumorigenic Irritant Reproductive
Maximum
Mutagenicity Acute
Carcinogenic
effect
recommended daily
dose (mmol)
toxicity LC50 potency
(mmol)
3a
3b
3c
3d
3f
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
No risk No risk
1.82e + 02
2.53e + 01
1.19e + 02
1.24e + 02
2.81e + 01
3.64e + 01
3.78e + 01
4.75e + 01
3.90e + 01
5.21e + 01
6.22e + 01
6.92e + 01
5.19e + 01
1.38e + 02
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
Inactive
5.85e + 00
1.42e + 01
2.20e + 01
2.10e + 01
9.98e + 00
8.42e + 00
8.94e + 00
9.88e + 00
4.13e + 00
1.34e + 01
7.71e + 00
7.23e + 00
6.44e + 00
5.88e + 00
Inactive
Inactive
Active
Active
Inactive
Inactive
Inactive
Active
3g
3h
3i
Medium risk No risk
Medium risk No risk
Medium risk No risk
3j
Active
3k
3l
Inactive
Inactive
Inactive
Inactive
Active
No risk
No risk
No risk
No risk
No risk
No risk
No risk
No risk
3q
3r
3t
Bold data represents the most active compounds in the series
Characterization of the synthesized derivatives
3.43 Hz, 1H, Ha), 3.41–3.46 (dd, Jab: 4.01 Hz, Jbx: 16.35 Hz,
1H, Hb), 3.71–3.82 (dd, Jax: 3.26 Hz, Jbx: 17.56 Hz, 1H,
Hx), 5.39 (s, 1H, Ar-OH), 6.84–7.86 (m, 12H, Ar). 13C
NMR (ppm, DMSO): 39.7 (CH2 pyrazoline), 42.5 (CH
pyrazoline), 115.6–128.4 (12CH benzene), 140.3–146.5
(3C benzene), 159.3 (C pyrazoline). MS (m/z): 457.89 (M+,
100%). Anal. Calcd. for C21H16ClN3O5S: C, 56.38; H, 3.61;
N, 6.26. Found: C, 55.56; H, 3.64; N, 6.30.
Intermediates were characterized by TLC, melting point and
mass spectra, while the final derivatives were subjected to
complete physicochemical (Table 1) and spectral char-
acterization and the values were found to be in accordance
with the proposed derivatives.
4-[5-(3,4-Dimethoxy-phenyl)-1-(4-nitro-benzenesulfonyl)-
4,5-dihydro-1H-pyrazol-3-yl]-phenol (3a) IR (cm−1): 3220
(N–H stretch), 2861 (C–H aromatic), 1637 (C=N stretch),
1516 (C–H deform), 1160, 1350 (sym, asym S(=O)2
stretch). 1H NMR (DMSO, δ ppm): 2.31–2.62 (d, Jab:
16.88 Hz, Jax: 3.36 Hz, 1H, Ha), 3.63 (m, 6H), 3.71–3.89
(dd, Jab: 3.74 Hz, Jbx: 17.12 Hz, 1H, Hb), 5.20 (s, 1H,
Ar–OH), 6.29–6.48 (dd, Jax: 3.61 Hz, Jbx: 16.23 Hz, 1H,
Hx), 6.78–7.22 (m, 3H, Ar), 7.44–7.51 (m, 4H, Ar),
8.65–8.80 (m, 4H, Ar). 13C NMR (ppm, DMSO): 40.12
(CH2 pyrazoline), 42.76 (CH pyrazoline), 56.80 (2CH3
methyl), 113.7 (4CH benzene), 126.4–130.2 (8CH ben-
zene), 143.5 (5C benzene), 160.3 (C pyrazoline). MS (m/z):
483.49 (M+, 100%). Anal. Calcd. for C23H21N3O7S: C,
57.14; H, 4.38; N, 8.69. Found: C, 57.13; H, 4.41; N, 8.73.
4-[5-Furan-2-yl-1-(4-nitro-benzenesulfonyl)-4,5-dihydro-1H-
pyrazol-3-yl]-phenol (3c) IR (cm−1): 3486 (N-H stretch),
3185 (C-H aromatic), 1641 (C=N stretch), 1525 (C-H
deform), 1165, 1347 (sym., asym S(=O)2 stretch). 1H NMR
(δ ppm, DMSO): 2.12–2.14 (dd, Jab: 17.08 Hz, Jax: 3.17 Hz,
1H, Ha), 3.33–3.37 (dd, Jab: 3.86 Hz, Jbx: 16.65 Hz, 1H, Hb),
3.40–3.82 (dd, Jax: 3.10 Hz, Jbx: 17.06 Hz, 1H, Hx), 5.23 (s,
1H, Ar-OH), 6.11–7.45 (m, 11H, Ar). 13C NMR (DMSO,
ppm): 37.8 (CH2 pyrazoline), 42.5 (CH pyrazoline), 106.2
(CH, furan), 114.7 (2CH, benzene), 123.6–130.4 (6CH
benzene), 145.3–154.8 (4C benzene), 159.4 (C furan),
160.8 (C pyrazoline). MS (m/z): 413.40 (M+1, 80%). Anal.
Calcd. for C19H15N3O6S: C, 55.20; H, 3.66; N, 10.16.
Found: C, 54.92; H, 4.17; N, 9.85.
4-[5-(4-Chloro-phenyl)-1-(4-nitro-benzenesulfonyl)-4,5-dihy-
dro-1H-pyrazol-3-yl]-phenol (3b) IR (cm−1): 3440 (N-H
stretch), 2861 (C-H aromatic), 1516 (C=N stretch), 1437
(C-H deform), 1169, 1351 (sym., asym S(=O)2 stretch). 1H
NMR (δ ppm, DMSO): 1.99–2.01 (dd, Jab: 17.16 Hz, Jax:
4-[1-(4-Nitro-benzenesulfonyl)-5-thiophen-2-yl-4,5-dihydro-
1H-pyrazol-3-yl]-phenol (3d) IR (cm−1): 3268 (N-H
stretch), 2876 (C-H aromatic), 1566 (C=N stretch), 1434
(C-H deform), 1212, 1352 (sym., asym S(=O)2 stretch). 1H
NMR (δ ppm, DMSO): 1.99–2.01 (dd, Jab: 15.74 Hz, Jax:

Medicinal Chemistry Research
3.85 Hz, 1H, Ha), 3.40–3.46 (dd, Jab: 3.95 Hz, Jbx: 16.69 Hz,
1H, Hb), 3.21–3.84 (dd, Jax: 3.27 Hz, Jbx: 17.44 Hz, 1H,
Hx), 5.46 (s, 1H, Ar-OH), 6.73–7.81 (m, 11H, Ar). 13C
NMR (ppm, DMSO): 39.7 (CH2 pyrazoline), 43.9 (CH
pyrazoline), 113.8–128.6 (9CH benzene), 122.5–126.2
(3CH thiophene), 138.4–151.7 (3C benzene), 161.0 (C
5-(3,4-Dimethoxy-phenyl)-3-naphthalen-1-yl-1-(4-nitro-ben-
zenesulfonyl)-4,5-dihydro-1H-pyrazole (3i) IR (cm−1):
3345 (N-H stretch), 2916 (C-H aromatic), 1594 (C=N
stretch), 1456 (C-H deform), 1167, 1350 (sym., asym S
1
(=O)2 stretch). H NMR (δ ppm, DMSO): 1.97–1.98 (dd,
Jab: 17.22 Hz, Jax: 3.52 Hz, 1H, Ha), 3.39–3.47 (dd, Jab:
3.87 Hz, Jbx: 16.73 Hz, 1H, Hb), 3.54–3.69 (dd, Jax:
3.18 Hz, Jbx: 17.26 Hz, 1H, Hx), 3.80–3.94 (m, 6H, methyl),
6.78–7.64 (m, 14H, Ar). 13C NMR (DMSO, ppm): 39.5
(CH2 pyrazoline), 42.8 (CH pyrazoline), 61.7 (2CH3),
113.7–132.5 (14CH benzene, 131.8–147.2 (8C benzene),
159.3 (C pyrazoline). MS (m/z): 517.55 (M+1, 80%). Anal.
Calcd. for C27H23N3O6S: C, 62.66; H, 4.48; N, 8.12. Found:
C, 62.70; H, 4.51; N, 8.13.
thiophene), 162.7 (C pyrazoline). MS (m/z): 429.47 (M+1
,
80%). Anal. Calcd. for C19H15N3O5S2: C, 53.14; H, 3.52;
N, 9.78. Found: C, 53.17; H, 3.48; N, 9.75.
3,5-Bis-(4-chloro-phenyl)-1-(4-nitro-benzenesulfonyl)-4,5-
dihydro-1H-pyrazole (3f) IR (cm−1): 3356 (N-H stretch),
2992 (C-H Aromatic), 1522 (C=N stretch), 1457 (C-H
deform), 1275, 1353 (sym., asym S( = O)2 stretch). 1H
NMR (δ ppm, DMSO): 1.90–1.94 (dd, Jab: 17.49 Hz, Jax:
3.64 Hz, 1H, Ha), 3.27–3.40 (dd, Jab: 4.04 Hz, Jbx: 17.24 Hz,
1H, Hb), 3.63–3.80 (dd, Jax: 3.77 Hz, Jbx: 16.59 Hz, 1H,
Hx), 7.05–7.74 (m, 12H, Ar). 13C NMR (ppm, DMSO,):
39.4 (CH2 pyrazoline), 42.7 (CH pyrazoline), 124.5–130.2
(12CH benzene), 134.7–141.3 (4C benzene), 160.7 (C
pyrazoline). MS (m/z): 476.33 (M+, 95%). Anal. Calcd. for
C21H15Cl2N3O4S: C, 52.95; H, 3.17; N, 8.82. Found: C,
53.01; H, 3.15; N, 8.83.
5-(4-Chloro-phenyl)-3-naphthalen-1-yl-1-(4-nitro-benzene-
sulfonyl)-4,5-dihydro-1H-pyrazole (3j) IR (cm−1): 3260
(N-H stretch), 2992 (C-H aromatic), 1565 (C=N stretch),
1514 (C-H deform), 1169, 1345 (sym., asym S(=O)2
stretch). 1H NMR (δ ppm, DMSO): 2.15–2.19 (dd, Jab:
16.68 Hz, Jax: 3.27 Hz, 1H, Ha), 3.83–3.88 (dd, Jab: 3.95 Hz,
Jbx: 17.10 Hz, 1H, Hb), 3.50–3.67 (dd, Jax: 4.12 Hz, Jbx:
16.97 Hz, 1H, Hx), 6.90–7.73 (m, 14H, Ar). 13C NMR
(ppm, DMSO): 39.2 (CH2 pyrazoline), 46.4 (CH pyrazo-
line), 124.2–129.0 (15CH benzene), 129.5–136.1 (7C ben-
zene), 158.7 (C pyrazoline). MS (m/z): 491.95 (M+, 100%).
Anal. Calcd. for C25H18ClN3O4S: C, 61.04; H, 3.69; N,
8.54. Found: C, 60.98; H, 3.71; N, 8.50.
3-(4-Chloro-phenyl)-5-furan-2-yl-1-(4-nitro-benzenesulfo-
nyl)-4,5-dihydro-1H-pyrazole (3g) IR (cm−1): 3156 (N-H
stretch), 3100 (C-H Aromatic), 1588 (C=N stretch), 1399
(C-H deform), 1166, 1345 (sym., asym S(=O)2 stretch). 1H
NMR (δ ppm, DMSO): 2.08–2.13 (dd, Jab: 15.31 Hz, Jax:
2.98 Hz, 1H, Ha), 3.39–3.44 (dd, Jab: 4.16 Hz, Jbx: 15.57 Hz,
1H, Hb), 3.61–3.79 (dd, Jax: 3.58 Hz, Jbx: 16.95 Hz, 1H,
Hx), 6.53–7.60 (m, 11H, Ar). 13C NMR (DMSO, ppm):
38.9 (CH2 pyrazoline), 42.5 (CH pyrazoline), 104.5–112.8
(2CH furan), 113.7–129.5 (8CH benzene), 139.2–136.8 (3C
benzene), 159.2 (C furan), 161.7 (C pyrazoline). MS (m/z):
431.85 (M+1, 70%). Anal. Calcd. for C19H14ClN3O5S:
C, 52.84; H, 3.27; N, 9.73. Found: C, 52.82; H, 3.30; N,
9.75.
5-Furan-2-yl-3-naphthalen-1-yl-1-(4-nitro-benzenesulfonyl)-
4,5-dihydro-1H-pyrazole (3k) IR (cm−1): 3312 (N-H
stretch), 3109 (C-H aromatic), 1598 (C=N stretch), 1523
(C-H deform), 1170, 1351 (sym., asym S(=O)2 stretch). 1H
NMR (δ ppm, DMSO): 2.48–2.51 (dd, Jab: 17.12 Hz, Jax:
3.41 Hz, 1H, Ha), 3.04–3.89 (dd, Jab: 4.01 Hz, Jbx: 16.23 Hz,
1H, Hb), 4.88–5.21 (dd, Jax: 3.28 Hz, Jbx: 17.46 Hz, 1H,
Hx), 6.80–6.93 (d, 2H, Ar), 7.43–7.54 (m, 4H, Ar),
7.66–7.85 (m, 7H, Ar). 13C NMR (DMSO, ppm): 50.7 (CH2
pyrazoline), 77.2 (CH pyrazoline), 124.4–126.9 (2CH
furan), 129.0–138.2 (11CH benzene), 133.7–145.2 (5C
benzene), 159.4 (C pyrazoline). MS (m/z): 447.46 (M+,
90%). Anal. Calcd. for C23H17N3O5S: C, 61.74; H, 3.83; N,
9.39. Found: C, 61.71; H, 3.80; N, 9.33.
3-(4-Chloro-phenyl)-1-(4-nitro-benzenesulfonyl)-5-thio-
phen-2-yl-4,5-dihydro-1H-pyrazole (3h) IR (cm−1): 3482
(N-H stretch), 3101 (C-H aromatic), 1614 (C=N stretch),
1398 (C-H deform), 1168, 1347 (sym., asym S(=O)2
stretch). 1H NMR (δ ppm, DMSO): 2.11–2.18 (dd, Jab:
16.83 Hz, Jax: 3.27 Hz, 1H, Ha), 4.13–4.20 (dd, Jab: 4.11 Hz,
Jbx: 16.58 Hz, 1H, Hb), 4.20–4.23 (dd, Jax: 3.66 Hz, Jbx:
16.85 Hz, 1H, Hx), 6.66–7.79 (m, 11H, Ar). 13C NMR
(ppm, DMSO): 39.7 (CH2 pyrazoline), 41.3 (CH pyrazo-
line), 121.4–136.5 (8CH benzene), 124.2–127.5 (3CH
thiophene), 128.6–143.1 (4C benzene), 139.6 (C thio-
3-Naphthalen-1-yl-1-(4-nitro-benzenesulfonyl)-5-thiophen-
2-yl-4,5-dihydro-1H-pyrazole (3l) IR (cm−1): 3292 (N-H
stretch), 3047 (C-H aromatic), 1580 (C=N stretch), 1513
(C-H deform), 1176, 1352 (sym., asym S(=O)2 stretch). 1H
NMR (δ ppm, DMSO): 2.08–2.09 (dd, Jab: 17.48 Hz, Jax:
2.99 Hz, 1H, Ha), 3.10–3.18 (dd, Jab: 3.74 Hz, Jbx: 17.04 Hz,
1H, Hb), 3.83–3.86 (dd, Jax: 3.26 Hz, Jbx: 16.36 Hz, 1H,
Hx), 6.60–7.92 (m, 14H, Ar). 13C NMR (ppm, DMSO):
40.6 (CH2 pyrazoline), 46.1 (CH pyrazoline), 122.5–129.2
phene), 156.8 (C pyrazoline). MS (m/z): 447.92 (M+1
,
100%). Anal. Calcd. for C19H14ClN3O4S2: C, 50.95; H,
3.15; N, 9.38. Found: C, 51.01; H, 3.18; N, 9.42.

Medicinal Chemistry Research
(11CH benzene), 123.4–125.8 (3CH thiophene),
137.8–148.1 (6C benzene), 161.5 (C pyrazoline). MS (m/z):
463.53 (M+, 95%). Anal. Calcd. for C23H17N3O4S2: C,
59.60; H, 3.70; N, 9.87. Found: C, 59.57; H, 3.75; N, 9.83.
Biological evaluation
Study animals
Animals were procured from the Animal House, Faculty of
Pharmacy, BBDNIIT, Lucknow, U.P., India and housed in
polypropylene cages with steel net, in a temperature con-
trolled room under standard living conditions of; 26 2 °C
and relative humidity of; 55 5% with regular 12 h light
and 12 h dark cycles and allowed free access to standard
laboratory food and water. All the animals were treated
humanely in accordance with the guidelines laid down by
the Institutional Animal Ethics Committee (IAEC). The
biological activity studies were approved by the IAEC with
the protocol number BBDNIIT/IAEC/009/2014.
2-[5-(3,4-Dimethoxy-phenyl)-1-(4-nitro-benzenesulfonyl)-
4,5-dihydro-1H-pyrazol-3-yl]-pyridine (3q) IR (cm−1):
3406 (N-H stretch), 3093 (C-H aromatic), 1608 (C=N
stretch), 1513 (C-H deform), 1174, 1344 (sym., asym S
1
(=O)2 stretch). H NMR (δ ppm, DMSO): 1.89–1.91 (dd,
Jab: 15.62 Hz, Jax: 3.17 Hz, 1H, Ha), 3.33–3.39 (dd, Jab:
3.74 Hz, Jbx: 17.11 Hz, 1H, Hb), 3.65–3.80 (dd, Jax:
3.54 Hz, Jbx: 16.91 Hz, 1H, Hx), 3.73–3.94 (m, 6H, methyl),
6.97–8.21 (m, 11H, Ar). 13C NMR (ppm, DMSO): 40.2
(CH2 pyrazoline), 45.7 (CH pyrazoline), 49.5 (6C, CH3),
114.9–137.2 (11CH benzene), 143.4–152.8 (6C benzene),
161.9 (C pyrazoline). MS (m/z): 468.48 (M+, 80%). Anal.
Calcd. for C22H20N4O6S: C, 56.40; H, 4.30; N, 11.96.
Found: C, 56.39; H, 4.32; N, 12.03.
Study design
For the study, animals were divided into 16 groups, each
group consisting of 6 animals (n = 6). All the mice were
treated at respective doses according to body weight.
Treatments including standard/vehicle/test compounds were
given at 1 mL/100 g body weight per oral (p.o.). Imipramine
(10 mg/kg body weight) for antidepressant activity, and
Diazepam (2 mg/kg body weight) for anti-anxiety activity
were respectively taken as the standard drugs. Carboxy
methyl cellulose (0.5% CMC solution) was taken as the
vehicle (control group). The treatment groups and respec-
tive doses are given in Table 2.
2-[5-(4-Chloro-phenyl)-1-(4-nitro-benzenesulfonyl)-4,5-dihy-
dro-1H-pyrazol-3-yl]-pyridine (3r) IR (cm−1): 3420 (N-H
stretch), 3069 (C-H aromatic), 1621 (C=N stretch), 1453
(C-H deform), 1175, 1343 (sym., asym S(=O)2 stretch). 1H
NMR (δ ppm, DMSO): 1.91–1.94 (dd, Jab: 17.36 Hz, Jax:
3.21 Hz, 1H, Ha), 3.64–3.48 (dd, Jab: 4.12 Hz, Jbx: 17.44 Hz,
1H, Hb), 3.69–3.85 (dd, Jax: 3.28 Hz, Jbx: 16.55 Hz, 1H,
Hx), 7.29–8.69 (m, 12H, Ar). 13C NMR (ppm, DMSO):
40.2 (CH2 pyrazoline), 44.5 (CH pyrazoline), 124.6–149.2
(12CH benzene), 137.1–146.4 (4C benzene), 154.2 (C
pyridine), 160.7 (C pyrazoline). MS (m/z): 442.88 (M+,
100%). Anal. Calcd. for C20H15ClN4O4S: C, 54.24; H, 3.41;
N, 12.65. Found: C, 54.22; H, 3.45; N, 12.67.
Antidepressant activity
The antidepressant activity of the test compounds was
evaluated by Porsolt’s behavioral despair or forced swim
test (FST) and Tail suspension test (TST) in mice. These
behavioral tests are used to evaluate the efficacy of anti-
depressant treatments and in predicting the activity of a
wide variety of antidepressants, such as MAO inhibitors and
atypical antidepressants (Porsolt 1981). They have good
predictive value for the assessment of antidepressant
potency in humans (Willner and Mitchell 2002).
2-[1-(4-Nitro-benzenesulfonyl)-5-thiophen-2-yl-4,5-dihydro-
1H-pyrazol-3-yl]-pyridine (3t) IR (cm−1): 3493 (N-H
stretch), 3116 (C-H aromatic), 1519 (C=N stretch), 1453
(C-H deform), 1164, 1344 (sym., asym S(=O)2 stretch). 1H
NMR (δ ppm, DMSO): 1.90–1.93 (dd, Jab: 17.23 Hz, Jax:
3.32 Hz, 1H, Ha), 3.46–3.50 (dd, Jab: 3.87 Hz, Jbx: 16.65 Hz,
1H, Hb), 3.82–3.89 (dd, Jax: 3.14 Hz, Jbx: 16.91 Hz, 1H,
Hx), 6.53–8.97 (m, 11H, Ar). 13C NMR (ppm, DMSO):
38.6 (CH2 pyrazoline), 43.2 (C pyrazoline), 115.6–128.3
(4CH benzene), 124.8–127.0 (7CH thiophene, pyridine),
140.5 (C thiophene), 144.9–151.1 (2C benzene), 153.4 (C
pyridine), 161.3 (C pyrazoline). MS (m/z): 414.46 (M+,
100%). Anal. Calcd. for C18H14N4O4S2: C, 52.16; H, 3.40;
N, 13.52. Found: C, 52.18; H, 3.44; N, 13.49.
Porsolt’s behavioral despair or FST in mice
The synthesized compounds were screened for their anti-
depressant activity using Porsolt’s behavioral despair test, i.
e, FST. It has been proposed that mice or rats are induced to
a characteristic behavior of immobility when they are forced
to swim in a restricted space from where they cannot
escape. In this test, the mice were plunged individually into
a Plexiglas cylinder containing water for 6 min. After the
first 2 min of the initial vigorous struggling, the animals
were immobile. When mice start floating in water in an

Medicinal Chemistry Research
upright position with slight movements in order to prevent
sinking, they were considered immobile and the duration of
immobility was recorded during the last 4 min of the 6 min
test. This behavior reflects a state of despair, which can be
reduced by several agents, which are therapeutically effec-
tive in human depression. Duration of immobility was
measured in control and animals treated with various doses
of a test drug or standard (Porsolt et al. 1977; Vogel 2002).
environment and the anxiety-related behavior is measured
by the degree to which the mouse avoids the unenclosed
arms of the maze. It is a standard test of fear and anxiety for
which the animal was placed in the center of an elevated 4-
arm maze, in which 2 arms are open (50 × 10 × 40 cm) and 2
arms are closed (50 × 10 × 40 cm), with an open roof. The
two open arms were opposite to each other. The maze was
elevated to a height of 50 cm. 1 h after oral administration of
the standard drug (Diazepam at a dose of 2 mg/kg b.w.), test
compound (at doses; 50 and 100 mg/kg b.w.) and control
(0.5% aqueous CMC suspension), the mice were placed in
the center of the maze, facing one of the closed arms.
During a 6 min test period, the following observations were
recorded: time spent in the closed arms and total number of
the arm entries (Lister 1987; Pellow et al. 1985).
TST in mice
Another facile method to evaluate antidepressant potential
is TST. It was designed in such a way so that a mouse is
suspended by the tail, with the help of a lever, and the
movements of the animal are recorded. The complete
duration of the test (6 min) can be divided into periods of
agitation and immobility. The rodents show the state of
immobility, when exposed to an inescapable stress, and this
has been hypothesized to reflect behavioral despair which in
turn may reflect depressive disorders in humans. When the
mice are suspended by the tail, the state of immobility
displayed by the mice after active and unsuccessful attempts
to escape is reduced by antidepressants. The percentage of
animals showing the passive behavior is counted and
compared with the vehicle treated controls. The duration of
immobility, in conjunction with measurement of locomotor
activity in different conditions, separates the locomotor
stimulant doses from antidepressant doses. This procedure
is simple, uses objective test situations and the results are in
accordance with the validated “behavioral despair” test
from Porsolt and the sensitivity to a wide range of drug
doses (Steru et al. 1985; Vogel 2002).
Neurotoxicity study
Neurotoxicity studies are used to evaluate the effect(s) of a
test substance on the central nervous system (CNS). Several
behavioral studies (such as; rotarod test, open-field/acto-
photometer test, turning on flat surface, and turning on
inclined plane) are employed to identify potential neuro-
toxicity in mice model. Two most commonly used methods,
i.e., rotarod and actophotometer tests, are used to identify
the effect of chemical compound (test compound) on neu-
romuscular coordination and locomotor activities, respec-
tively (Parasuraman 2011).
Neuromuscular coordination study (rotarod test)
The rota rod test is used to evaluate the activity of drugs
interfering with motor coordination, i.e. neurotoxicity. In
1956, Dunham and Miya suggested that the skeletal muscle
relaxation induced by a test compound could be evaluated
by testing the ability of mice or rats to remain on a revol-
ving rod. Male mice, with a weight between 20 and 30 g,
undergo a pretest on the apparatus. Only those animals
which have demonstrated their ability to remain on the
revolving rod for at least 1 min are used for the test. The test
compounds are administered intraperitoneally or orally. 1 h
after the oral administration of the test compounds/control,
the mice are placed for 1 min on the rotating rod. Normal
mice remain on a rod rotating at this speed indefinitely.
Neurologic toxicity was defined as the failure of the animal
to remain on the rod for 1 min at the tested doses. The
number of animals falling from the roller during this time is
counted (qualitative test) or one can quantify the values in
terms of mean fall off time. The dose which impairs the
ability of 50% of the mice to remain on the revolving rod is
considered as the endpoint (Bhandari et al. 2013; Vogel
2002).
Anti-anxiety activity
The maze model in mice is widely used for the evaluation of
anti-anxiety activity. Out of the many possibilities to
modify maze tests, water maze, the Y-maze, the radial
maze, and the elevated plus maze have found acceptance in
many laboratories. The test has been proposed for selective
identification of anxiolytic and anxiogenic drugs. Anxioly-
tic compounds, by decreasing anxiety, increase the open
arm exploration time and decrease the time spent in closed
arm; anxiogenic compounds have the opposite effect. The
values of the treated groups are registered and expressed as
percentage of controls. Benzodiazepines and valproates
decrease motor activity and increase open arm exploratory
time (Vogel 2002).
Elevated plus-maze test
The elevated plus-maze is used to determine the mouse’s
unconditioned response to
a
potentially dangerous

Medicinal Chemistry Research
Locomotor activity (actophotometer/open field test)
simulations 2005 force field, and it gave the corresponding
energy minima 3D conformers of the ligands. The default
settings were used for all the other parameters. All the
ligand atoms, but no protein atoms, were allowed to move
during the calculations. To validate the docking protocol,
re-docking experiment was performed in which the ligand
conformation of co-crystal ligand was extracted from the
crystal structure of the corresponding MAO-A protein/
ligand complex and later docked back into the binding
pocket. GLIDE was able to perfectly reproduce the
experimental position of the ligand, confirming the ability
of the method to accurately predict the binding
conformation.
Most of the CNS acting drugs influence the locomotor
activities in humans and animals; therefore it is used as an
index of wakefulness (alertness) of mental activity. The
CNS depressant drugs, such as barbiturates and alcohol,
reduce the motor activity while the stimulants such as caf-
feine and amphetamines increase the activity. To rule out
these effects of tested compounds on immobility period in
FST and TST, the horizontal locomotor activity of control
and test animals were recorded for a period of 10 min using
Medicraft Actophotometer (Model No. 600-4D, INCO,
Ambala, India). The apparatus consists of a square arena
(30 × 30 × 25 cm) with wire mesh bottom, in which an
animal moves. The actophotometer operates on photo-
electric cells which are connected in circuit with a counter.
When the beam of light falling on the photo cell is cut off
by the animal, a count is recorded (Dhingra and Goyal
2008).
In-silico prediction of pharmacokinetic properties
Nearly 40% of drug candidates fail in clinical trials due to
poor absorption, distribution, metabolism, and excretion
(ADME) properties. These late-stage failures contribute
significantly to the rapidly escalating cost of new drug
development. The ability to detect the problematic candi-
dates early can dramatically reduce the amount of wasted
time and resources, and streamline the overall development
process. QikProp (version 4.2, Schrödinger, LLC, New
York, NY, 2014) program was used for in silico prediction
of pharmacokinetic properties of the synthesized
compounds.
Acute toxicity study
Acute toxicity testing is carried out to determine the effect
of a single dose on a particular animal species. In the pre-
sent study, acute oral toxicity (LD50) of the two most active
final derivatives (3d and 3l) was performed as per guide-
lines laid by Organization for Economic Co-operation and
Development (OECD) guideline No 423 “Acute Oral
Toxicity-Acute Toxic Class Method”. The compounds were
administered orally at four fixed dose levels (5, 50, 300, and
2000 mg/kg body weights), after 4 h of fasting. After dose
administration, food but not water was withheld for 2 h. The
body weight of all the mice were recorded on study days-
D0 (initiation), D1, D7 and D14. The animals were observed
for 4 h post the treatment and thereafter for 14 days for
mortality, including various signs of toxicity such as,
changes in skin and fur, behavior patterns, convulsions,
tremors and death (OECD Guidelines 2001).
In-silico toxicity prediction
There are a large number of freely available computer
programs to envisage the in silico toxicity of the com-
pounds. Two such softwares, used in this study are;
LAZAR and OSIRIS Property explorer. LAZAR provides a
generic tool for predicting complex toxicological end
points, such as- carcinogenicity, long-term toxicity, and
reproductive toxicity. Virtual Computational Chemistry
Laboratory maintains OSIRIS as a fundamental part of
Actelion’s in house substance registration system. This
calculates various drug-related properties of chemical
structures including some toxicity parameters and drug
likeness. Predicted outcomes are rated and color coded.
Properties such as mutagenicity or a poor intestinal
absorption having higher risks of undesired effects are
shown in red, whereas a green color indicates drug-conform
behavior (Klebe 2000).
Molecular docking studies
Molecular docking studies were performed on all the syn-
thesized compounds in order to gain structural insights into
the binding mode of the ligand with the biological target
MAO-A enzyme crystal structure (PDB ID: 2Z5X) using
GLIDE (version 6.5, Schrödinger, LLC, New York, NY,
2014). The MAO protein crystal structure used for mole-
cular docking was retrieved from the Protein Data Bank
(PDB), and subsequently optimized and minimized with the
“protein preparation wizard” workflow. The ligands were
built using Maestro 10.0 build panel and prepared by Lig-
Prep 3.2 version v25111(Schrödinger, LLC, New York,
NY, 2014) application, that uses optimized potential liquid
Statistical analysis
All the values of the experimental results are expressed as
mean SD and analyzed by one-way ANOVA, followed by
Dunnett’s test for the possible significance (P < 0.05)
identification between various groups. Statistical analysis

Medicinal Chemistry Research
was carried out using Graph Pad Prism 5.0 (Graph Pad
Software, San Diego, CA).
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Jayaprakash V, Sinha BN, Ucar G, Ercan A (2008) Pyrazoline-based
mycobactin analogues as MAO-inhibitors. Bioorg Med Chem
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Acknowledgements We express our sincere gratitude to Central Drugs
Research Institute (CDRI), Lucknow, India and Department of
Chemistry, Banasthali Vidyapith University, Banasthali, Rajasthan,
India for providing the library and sophisticated analytical instrument
facilities. Authors are thankful to the All India Council for Technical
Education (AICTE), New Delhi, India, for providing grant under the
Research Promotion Scheme (Grant No.: 8023/RID/RPS/30 (Pvt.)
2011-12), through which the computational software facility has been
made available at the host institute. We also acknowledge the technical
support team/application scientists of Schrodinger Inc. for their help
during computational studies.
Klebe G (2000) Recent developments in structure-based drug design. J
Mol Med 78:269–281
Lidstrom P, Tierney J, Wathey B, Westman J (2001) Microwave
assisted organic synthesis- a review. Tetrahedron 57:9225–9283
Lister RG (1987) The use of a plus-maze to measure anxiety in the
mouse. Psychopharmacol (Berl) 92:180–185
Compliance with ethical standards
Conflict of interest The authors declare that they have no conflict of
interest.
Maccioni E, Alcaro S, Orallo F, Cardia MC, Distinto S, Costa G,
Yanez M, Sanna ML, Vigo S, Meleddu R, Secci D (2010)
Synthesis of new 3-aryl-4,5-dihydropyrazole-1-carbothioamide
derivatives. An investigation on their ability to inhibit mono-
amine oxidase. Eur J Med Chem 45:4490–4498
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