N1-benzenesulfonyl-2-pyrazoline hybrids in neurological disorders: Syntheses, biological screening and computational studies

Article abstract of DOI:10.17179/excli2017-871

A novel series of 1,3,5-trisubstituted-2-pyrazolines (5a-5t) was prepared via Claisen Schmidt condensation, followed by heterocyclization with hydrazine hydrate, substitution of N1 hydrogen of 2-pyrazoline nucleus with 4-chlorobenzenesulfonylchloride, app

Full text of DOI:10.17179/excli2017-871

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10, 2017, accepted: January 15, 2018, published: January 19, 2018
Original article:
N1-BENZENESULFONYL-2-PYRAZOLINE HYBRIDS IN
NEUROLOGICAL DISORDERS: SYNTHESES, BIOLOGICAL
SCREENING AND COMPUTATIONAL STUDIES
Avinash C. Tripathi1, Savita Upadhyay1, Sarvesh Paliwal2, Shailendra K. Saraf1*
1
Division of Pharmaceutical Chemistry, Faculty of Pharmacy, Babu Banarasi Das Northern
India Institute of Technology, Lucknow-226028, U.P., India
Professor and Head, Department of Pharmacy, Banasthali Vidyapith, Banasthali,
2
Tonk-304022, Rajasthan, India
E-mails: aviniec31@gmail.com; savvypharma@gmail.com; y
paliwalsarvesh@yahoo.com; dirpharmniec@gmail.com
*
Corresponding author:Prof. (Dr.) Shailendra K. Saraf, Director (Pharmacy), Division of
Pharmaceutical Chemistry, Faculty of Pharmacy, Babu Banarasi Das Northern India Insti-
tute of Technology, BBD City, Faizabad Road, Chinhat, Lucknow-226028, U.P., India.
Voice Contact: +91-522-3911052 (office), +919839228022(mobile),
Fax: +91-522-3911152,E-mail: dirpharmniec@gmail.com
http://dx.doi.org/10.17179/excli2017-871
This is an Open Access article distributed under the terms of the Creative Commons Attribution License
(http://creativecommons.org/licenses/by/4.0/).
ABSTRACT
A novel series of 1,3,5-trisubstituted-2-pyrazolines (5a-5t) was prepared via Claisen Schmidt condensation, fol-
lowed by heterocyclization with hydrazine hydrate, substitution of N1 hydrogen of 2-pyrazoline nucleus with 4-
chlorobenzenesulfonylchloride, applying conventional and green chemistry approaches. Among the two, micro-
wave assisted organic synthesis (MAOS) emerged as a better synthetic tool in terms of faster reaction rate and
high yield. Various physicochemical and spectral studies were conducted to characterize the synthesized deriva-
1
tives including- IR, Mass, H-NMR, 13C-NMR and elemental analysis. During pharmacological evaluation,
compound 5b showed excellent anti-anxiety activity and compound 5k exhibited the best antidepressant effect at
the tested doses, 50 and 100 mg/kg b.w., being comparable to diazepam and imipramine, respectively. The dock-
ing experiments confirmed the probable mechanism of neuropharmacological action, showing excellent affinity
towards MAO-A target protein, which was also evidenced from some of the key interactions with binding site
residues Ala68, Tyr69 and Phe352. Furthermore, complimentary in silico pharmacokinetic recital without any
potential risk of neurotoxicity (as evaluated by rotarod and actophotometer tests), or carcinogenicity, mutagenici-
ty, reproductive toxicity, acute toxicity and irritancy (as predicted by LAZAR and OSIRIS programs) signified
their probable use in depression and anxiety disorders.
Keywords: 2-Pyrazolines, antidepressant and anti-anxiety, neurotoxicity, microwave synthesis, molecular dock-
ing, in silico ADME prediction
INTRODUCTION
the brain, like dopamine (DA), norepineph-
rine (NE), serotonin (5-HT), and gamma
amino butyric acid (GABA), is the main
cause of depressive mental disorders. These
NTs are released during neurotransmission
and are degraded by the MAOs enzymes.
Monoamine oxidase (MAO) regulates
monoaminergic homeostasis and neuro-
transmission in the nervous system. Low
level of certain neurotransmitters (NTs) in
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EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10, 2017, accepted: January 15, 2018, published: January 19, 2018
Monoamine oxidase inhibitors (MAOIs) yaprakash et al., 2008; Karuppasamy et al.,
block the action of MAOs, and thus increase 2010; Maccioni et al., 2010; Manna et al.,
the concentration of NTs in the brain (Mito- 2002; Mishra and Sasmal, 2011; Sahoo et al.,
ma and Ito, 1992; Meyer et al., 2006). The 2010; Agrawal et al., 2012; Gautam et al.,
antidepressant effect of a hydrazine based 2010). Considering these facts, some 1,3,5-
anti-tubercular drug, iproniazid (a structural trisubstituted-2-pyrazolines were synthesized
analog of isoniazid) started the journey of by integrating some novel aromatic and het-
development of MAOIs. This discovery ero-aromatic substitutions at 3rd and 5th posi-
showed the way to design and produce some tions, respectively. Microwave facilitated
more effective analogs such as phenelzine synthetic technique was also utilized to pre-
(Zeller and Barsky, 1952). MAOIs belong to pare the proposed compounds and the results
the first generation antidepressants used for were compared to that of the conventional
decades to treat the patients suffering from heating methods (Lidstrom et al., 2001). This
high level of anxiety, atypical depression work is in continuation to the previous
(Pletscher, 1991), anergic bipolar depression communications by our group (Tripathi et
and treatment resistant depression (Thase, al., 2016, Upadhyay et al., 2017; Bhandari et
2012), specific phobias, post-traumatic stress al., 2013) with some novel derivatives hav-
disorder and migraine headaches resistant to ing promising potential in the field.
other therapies (Gareri et al., 2000). Two
major therapeutic categories of MAOI: the
MAO-A inhibitors in certain mental disor-
ders such as depression and anxiety (Amrein
et al., 1999) and MAO-B inhibitors proved
their remedial value in neurodegenerative
diseases (Youdim et al., 2006; Foley et al.,
2000) including Parkinson’s (Cesura and
Pletscher, 1992) and Alzheimer’s (Volz and
Gleiter, 1998). The initial hydrazine class of
MAO inhibitors was associated with some
severe adverse effects such as liver toxicity
and cheese reaction (Brown et al., 1989).
These side-effects were correlated to nonse-
lective and irreversible MAO inhibition.
These findings prompted research to develop
selective and reversible type of MAO (A and
B) inhibitors. Pyrazoline derivatives have at-
tracted substantial attention for years, chiefly
1,3,5-trisubstituted-2-pyrazoline pharmaco-
phore is allied with encouraging neurological
activities such as tranquilizer, anticonvulsant
and antidepressant (Kaplancikli et al., 2010;
Ozdemir et al., 2008; Palaska et al., 2001;
Rajendra Prasad et al., 2005; Ruhoglu et al.,
2005), psychoanaleptic, MAO inhibitory and
other biological activities (Chimenti et al.,
2004; 2010; Gokhan et al., 2003; Gokhan-
Kelekci et al., 2009; Jagrat et al., 2011; Ja-
MATERIALS AND METHODS
S. D. Fine Chemicals and Sigma Aldrich,
Mumbai, India supplied the chemicals and
reagents for synthesis and the pre-coated
TLC sheets were obtained from Merck
Chemicals, India and were used as such. Mi-
crowave assisted organic synthesis (MAOS)
was performed on Raga's Scientific Micro-
wave System (Ragatech, Pune, Maharashtra,
India).
Chemistry
The reaction of suitably substituted aro-
matic/heteroaromatic ketones with different
aldehydes, in alkaline medium, yielded sub-
stituted chalcones (1a-1t) via Claisen-
Schmidt condensation. Then, the formed
chalcones were reacted with hydrazine hy-
drate (in excess) to give 2-pyrazoline deriva-
tives (2a-2t). Finally, the N1 hydrogen of the
2-pyrazoline nucleus was replaced with 4-
chlorobenzenesulfonylchloride (5a-5t), as
given in Figure 1. The reaction progress was
examined by thin layer chromatography
(TLC), using pre-coated silica gel G plates as
stationary phase and iodine vapors/UV light
as the visualizing agents.
127

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10, 2017, accepted: January 15, 2018, published: January 19, 2018
CH3
R-CHO
+
R'
O
Aldehyde
Ketone
C2H5OH, KOH
0-10 oC, Stir,
24-48 hrs.
Conventional
Method
MWI: 120-280W, Microwave
60-230s Method
O
H
C
R
C
R'
H
Chalcones (1a-1t)
NH2NH2.H2O, C2H5OH
Microwave
Method
Conventional
Method
Reflux,
3-6 hrs.
MWI: 240-350W,
50-400s
Hb
Ha
R
Hx
R'
N NH
3,5-Disubstituted 2-pyrazoline derivatives (2a-2t)
4-Chlorobenzenesulfonylchloride
Microwave
Method
Conventional
Method
Stir,
1-4 hrs.
MWI: 210-350W,
80-280s
R
Hx
Hb
O
Ha
N S
O
1,3,5-Trisubstituted 2-pyrazoline derivatives (5a-5t)
Cl
N
R'
OCH3
S
O
Cl
Where R:
and R':
OCH3
OH
Cl
N
Figure 1: Synthesis of 1,3,5-Trisubstituted-2-pyrazoline derivatives
Synthesis of chalcone derivatives (1a-1t)
Synthesis of 3,5-disubstituted-2-pyrazoline
The proposed chalcone derivatives of the derivatives(2a-2t)
first step were synthesized by reacting suita-
The 3,5-disubstituted-2-pyrazoline deriv-
bly substituted aldehydes and ketones, in atives of the second step were synthesized by
equimolar ratio, via conventional and mi- reacting different chalcone derivatives of the
crowave assisted organic synthesis (MAOS) first step with hydrazine hydrate (excess),
procedures (Tripathi et al., 2016; Upadhyay using conventional and MAOS procedures
et al., 2017; Agrawal et al., 2012; Gautam et (Tripathi et al., 2016; Upadhyay et al., 2017).
al., 2010).
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EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10, 2017, accepted: January 15, 2018, published: January 19, 2018
Synthesis of 1,3,5-trisubstituted-2-
pyrazoline derivatives (5a-5t)
Avance-400, FTNMR spectrometer (Bruker,
Tech. Pvt. Ltd., USA) at 400MHz and the
Conventional synthesis: Appropriately chemical shifts are reported in parts per mil-
1
substituted
2-pyrazoline
derivatives lion (δ value), taking TMS (δ 0 ppm for H
(0.001M) of the second step reacted with 4- NMR) as the internal standard: 2.03-2.09
chlorobenzenesulfonylchloride (0.002M) by (dd, Jab: 16.77 Hz, Jax: 3.58 Hz, 1H, Ha),
stirring, using THF (10 mL) as the solvent. 2.73-2.78 (dd, Jab: 3.85 Hz, Jbx: 17.11 Hz,
Continued the stirring for 1-4 hrs, poured the 1H, Hb), 3.81-3.93 (dd, Jax: 3.50 Hz, Jbx:
reaction mixture in a petri plate and evapo- 17.05 Hz, 1H, Hx), 3.97-4.10 (m, 6H, me-
rated the solvent up to dryness. Re- thyl), 5.23-5.25 (s, 1H, Ar-OH), 6.56-7.90
precipitated the crude product using acetoni- (m, 11H, Ar). 13C NMR (DMSO, ppm): 37.9
trile/methanol and re-crystallized from ace- (CH2 pyrazoline), 43.0 (CH pyrazoline),
tonitrile/methanol to obtain the pure product 113.8-146.3 (12CH benzene), 147.5-159.2
(Upadhyay et al., 2017).
(7C benzene), 160.1 (C pyrazoline). Mass
MAOS: Appropriately substituted 3,5- spectra were recorded on Waters UPLC-
disubstituted-2-pyrazolines (0.001M) were TQD Mass Spectrometer instrument (Waters
reacted
with
4-chlorobenzenesulfonyl- Corporation, USA) using LC-ESI or APCI-
chloride (0.002M) under microwave irradia- MS Technique; MS (m/z): 473 (M+, 100 %).
tion (MWI: 210-350W; 80-280s), taking Elemental analysis was performed on Perkin
THF (10 mL) as the solvent. The reaction Elmer-2400, Series-II Analyzer (Waltham,
mixture was poured in a petri plate and Massachusetts, USA). Anal. Calcd. for
evaporated the solvent up to dryness. The C23H21ClN2O5S: C, 58.41; H, 4.48; N, 5.92.
crude product was re-precipitated using ace- Found: C, 58.39; H, 4.50; N, 5.89.
tonitrile/methanol and recrystallized from
4-[1-(4-Chloro-benzenesulfonyl)-5-(4-
acetonitrile/methanol to get the purified de-
chloro-phenyl)-4,5-dihydro-1H-pyrazol-3-
rivative (Upadhyay et al., 2017).
yl]-phenol (5b)
IR (cm-1): 3359 (N-H stretch), 3142 (C-H
Aromatic), 1606 (C=N stretch), 1516 (C-H
Characterization of the synthesized 1,3,5-
trisubstituted-2-pyrazoline derivatives
deform), 1165, 1351 (sym., asym S(=O)2
First and second step intermediate com-
1
stretch). H-NMR ( δ ppm, DMSO): 1.98-
pounds were characterized by TLC, melting
1.99 (dd, Jab: 17.12 Hz, Jax: 3.41 Hz, 1H,
point (determined by open capillary method
Ha), 3.40-3.48 (dd, Jab: 4.01 Hz, Jbx: 16.23
and are uncorrected) and mass spectrometric
Hz, 1H, Hb), 3.70-3.80 (dd, Jax: 3.28 Hz, Jbx:
techniques. However, comprehensive physi-
17.46 Hz, 1H, Hx), 5.39-5.45 (s, 1H, Ar-
cochemical (Table 1) and spectral characteri-
OH), 6.88-7.89 (m, 12H, Ar). 13C NMR
zation was undertaken for the final deriva-
(DMSO, ppm): 38.6 (CH2 pyrazoline), 43.2
tives and the values were found to be in
(CH pyrazoline), 115.6-140.3 (12CH ben-
agreement.
zene), 158.3-160.1 (3C benzene), 161.2 (C
4-[1-(4-Chloro-benzenesulfonyl)-5-(3,4-
dimethoxy-phenyl)-4,5-dihydro-1H-pyrazol-
3-yl]-phenol (5a)
pyrazoline). MS (m/z): 447 (M+, 100 %).
Anal. Calcd. for C21H16Cl2N2O3S: C, 56.38;
H, 3.61; N, 6.26. Found: C, 57.42; H, 3.59;
IR spectra were recorded on Bruker FT- N, 6.24.
IR, ALPHA-T (Eco-ATR) spectrophotome-
ters, (Bruker Corporation., USA) and the
values are expressed in cm-1. 3220 (N-H
stretch), 2865 (C-H Aromatic), 1650 (C=N
stretch), 1515 (C-H deform), 1159, 1350
1
(sym., asym S(=O)2 stretch). H-NMR and
13C-NMR spectra were recorded on Bruker
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EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10, 2017, accepted: January 15, 2018, published: January 19, 2018
Table 1: Comparative study of physicochemical properties of synthesized 1,3,5-trisubstituted-2-pyrazoline derivatives (5a-5t)
Com-
pounds
Structure
Molecular
Formula
Color and
State
Solubility
Rf
Melting Conventional
Microwave Assisted Organic
Value Range
Synthesis (Reflux- Synthesis (MAOS)
(0C)
ing)
Reaction
Time (h)
2.5
%
Microwave Reaction % Yield
Yield Power (W) Time (s)
HO
5a
5b
C23H21ClN Cream
Acetonitrile,
acetone,
DMSO
0.67
0.92
206-
208
47
68
210-240
130
85
66
70
OCH3
OCH3
2O5S
yellow
N
N
colored
amorphous
solid
O
S
O
Cl
Cl
C21H16Cl2
N2O3S
Colorless
crystalline
solid
Methanol,
DMSO,
chloroform,
acetone
198-
200
2.0
210
HO
O
N
N
S
O
Cl
Cl
O
5c
5d
5f
C19H15ClN Light brown Methanol,
2O4S colored acetonitrile,
amorphous chloroform,
0.88
0.75
0.52
162-
164
4.5
3.5
2.0
58
57
45
240-280
240-350
210-240
210
200
150
81
82
78
O
N
HO
HO
N
S
solid
acetone,
DMSO
O
S
C19H15ClN Brown col-
Methanol,
148-
150
2O3S2
ored amor- acetonitrile,
phous solid acetone,
DMSO
O
N
N
S
O
Cl
Cl
C21H15Cl3
N2O2S
Grey col-
Methanol,
185-
187
ored amor- acetonitrile,
phous solid chloroform,
acetone,
O
N
Cl
N
S
DMSO
O
Cl
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EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
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Com-
pounds
Structure
Molecular
Formula
Color and
State
Solubility
Rf
Melting Conventional
Microwave Assisted Organic
Value Range
Synthesis (Reflux- Synthesis (MAOS)
(0C)
ing)
Reaction
Time (h)
4.0
%
Microwave Reaction % Yield
Yield Power (W) Time (s)
45
O
C19H14Cl2N
2O3S
5g
5h
Black col-
ored amor- acetone,
phous solid DMSO
Acetonitrile,
0.80
0.66
120-
122
240-350
280-350
130
100
86
70
O
N
Cl
N
S
O
Cl
S
C19H14Cl2N
2O2S2
Yellowish
brown col-
Acetonitrile,
acetone,
193-
195
2.5
57
ored amor- DMSO
phous solid
O
N
Cl
N
S
O
Cl
OCH3
OCH3
C27H23ClN2
O4S
5i
5j
Orange
brown col-
ored amor- DMSO
phous solid
Methanol,
acetone,
0.92
0.58
168-
170
1.0
2.5
48
51
210-280
100
80
63
85
N
N
O
O
S
Cl
Cl
C25H18Cl2N
2O2S
Cream col- Acetonitrile,
ored amor- acetone,
phous solid DMSO
178-
180
280
N
N
O
S
O
Cl
C23H17ClN2
O3S
O
5k
Black col-
ored amor- DMSO, ace-
phous solid tonitrile
Acetone,
0.77
218-
220
3.0
32
210-280
220
86
N
N
O
O
S
Cl
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EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10, 2017, accepted: January 15, 2018, published: January 19, 2018
Com-
pounds
Structure
Molecular
Formula
Color and
State
Solubility
Rf
Melting Conventional
Microwave Assisted Organic
Value Range
Synthesis (Reflux- Synthesis (MAOS)
(0C)
ing)
Reaction
Time (h)
3.0
%
Microwave Reaction % Yield
Yield Power (W) Time (s)
97
C23H17ClN2
O2S2
5l
Black col-
ored amor- acetone,
phous solid DMSO
Acetonitrile,
0.64
112-
114
280-350
180
94
S
N
N
S
O
O
Cl
OCH3
OCH3
C22H20ClN3
O4S
5q
5r
5t
Brown col-
Methanol,
0.90
0.78
0.60
180-
182
2.5
2.0
3.0
30
93
48
280
160
175
260
71
68
72
ored amor- acetonitrile,
phous solid chloroform,
acetone,
O
N
N
S
N
DMSO
O
Cl
Cl
C20H15Cl2N
3O2S
Yellowish
brown col-
ored amor- chloroform,
phous solid acetone,
DMSO
Methanol,
acetonitrile,
116-
118
210-350
280-350
N
N
N
O
S
O
Cl
S
C18H14ClN3
O2S2
Brown col-
Methanol,
138-
140
ored amor- acetonitrile,
phous solid acetone,
DMSO
O
N
N
S
N
O
Cl
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EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
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(12CH benzene), 136.1-141.9 (4C benzene),
4-[1-(4-Chloro-benzenesulfonyl)-5-furan-2-
161.2 (C pyrazoline). MS (m/z): 463 (M+,
55 %). Anal. Calcd. for C21H15Cl3N2O2S: C,
54.15; H, 3.25; N, 6.01. Found: C, 54.11; H,
3.22; N, 6.00.
yl-4,5-dihydro-1H-pyrazol-3-yl]-phenol (5c)
IR (cm-1): 3472 (N-H stretch), 3239 (C-H
Aromatic), 1602 (C=N stretch), 1434 (C-H
deform), 1159, 1348 (sym., asym S(=O)2
1
stretch). H NMR (δ ppm, DMSO): 2.14- 1-(4-Chloro-benzenesulfonyl)-3-(4-chloro-
2.16 (dd, Jab: 17.00 Hz, Jax: 3.18 Hz, 1H, Ha), phenyl)-5-furan-2-yl-4,5-dihydro-1H-
3.27-3.36 (dd, Jab: 3.88 Hz, Jbx: 16.69 Hz, pyrazole (5g)
1H, Hb), 3.42-3.84 (dd, Jax: 3.05 Hz, Jbx:
IR (cm-1): 3330 (N-H stretch), 3092 (C-H
16.96 Hz, 1H, Hx), 5.20 (s, 1H, Ar-OH), Aromatic), 1685 (C=N stretch), 1539 (C-H
6.04-7.66 (m, 11H, Ar). 13C NMR (DMSO, deform), 1168, 1355 (sym., asym S(=O)2
1
ppm): 40.1 (CH2 pyrazoline), 44.5 (CH pyra- stretch). H NMR (δ ppm, DMSO): 2.08-
zoline), 104.2-142.9 (11CH Ar), 135.3-158.6 2.13 (dd, Jab: 15.31 Hz, Jax: 2.98 Hz, 1H, Ha),
(4C benzene), 159.0 (C furan), 160.7 (C py- 3.39-3.44 (dd, Jab: 4.16 Hz, Jbx: 15.57 Hz,
razoline). MS (m/z): 229 (M+, 100 %). Anal. 1H, Hb), 3.61-3.79 (dd, Jax: 3.58 Hz, Jbx:
Calcd. for C19H15ClN2O4S: C, 56.65; H, 16.95 Hz, 1H, Hx), 6.53-7.60 (m, 11H, Ar).
3.75; N, 6.95. Found: C, 56.66; H, 3.77; N, 13C NMR (DMSO, ppm): 39.9 (CH2 pyrazo-
6.93.
line), 42.5 (CH pyrazoline), 107.7-128.5
(11CH Ar), 130.2-136.8 (3C benzene), 159.0
(C furan), 161.7 (C pyrazoline). MS (m/z):
421 (M+, 65 %). Anal. Calcd. for
C19H14Cl2N2O3S: C, 54.17; H, 3.35; N, 6.65.
Found: C, 54.20; H, 3.39; N, 6.61.
4-[1-(4-Chloro-benzenesulfonyl)-5-thiophen-
2-yl-4,5-dihydro-1H-pyrazol-3-yl]-phenol
(5d)
IR (cm-1): 3270 (N-H stretch), 3010 (C-H
Aromatic), 1615 (C=N stretch), 1463 (C-H
deform), 1189, 1382 (sym., asym S(=O)2 1-(4-Chloro-benzenesulfonyl)-3-(4-chloro-
1
stretch). H NMR (δ ppm, DMSO): 1.99- phenyl)-5-thiophen-2-yl-4,5-dihydro-1H-
2.00 (dd, Jab: 15.72 Hz, Jax: 3.86 Hz, 1H, Ha), pyrazole (5h)
3.40-3.48 (dd, Jab: 3.94 Hz, Jbx: 16.70 Hz,
IR (cm-1): 3345 (N-H stretch), 3056 (C-H
1H, Hb), 3.71-3.85 (dd, Jax: 3.28 Hz, Jbx: Aromatic), 1621 (C=N stretch), 1471 (C-H
17.46 Hz, 1H, Hx), 5.45 (s, 1H, Ar-OH), deform), 1165, 1393 (sym., asym S(=O)2
1
6.75-7.80 (m, 11H, Ar). 13C NMR (DMSO, stretch). H NMR (δ ppm, DMSO): 2.10-
ppm): 39.4 (CH2 pyrazoline), 44.8 (CH pyra- 2.19 (dd, Jab: 16.88 Hz, Jax: 3.29 Hz, 1H, Ha),
zoline), 113.8-138.6 (11CH Ar), 120.1-151.7 4.15-4.22 (dd, Jab: 4.01 Hz, Jbx: 16.78 Hz,
(4C benzene), 161.3 (C thiophene), 162.4 (C 1H, Hb), 4.20-4.23 (dd, Jax: 3.63 Hz, Jbx:
pyrazoline). MS (m/z): 419 (M+, 95 %). 16.91 Hz, 1H, Hx), 6.65-7.79 (m, 11H, Ar).
Anal. Calcd. for C19H15ClN2O3S2: C, 54.47; 13C NMR (DMSO, ppm): 39.7 (CH2 pyrazo-
H, 3.61; N, 6.69. Found: C, 54.43; H, 3.62; line), 41.3 (CH pyrazoline), 121.4-136.5
N, 6.67.
(11CH Ar), 128.6-134.1 (3C benzene), 139.4
(C thiophene), 155.8 (C pyrazoline). MS
(m/z): 437 (M+, 40 %). Anal. Calcd. for
C19H14Cl2N2O2S2: C, 52.18; H, 3.23; N,
6.41. Found: C, 52.17; H, 3.20; N, 6.47.
1-(4-Chloro-benzenesulfonyl)-3,5-bis-(4-
chloro-phenyl)-4,5-dihydro-1H-pyrazole (5f)
IR (cm-1): 3315 (N-H stretch), 3100 (C-H
Aromatic), 1616 (C=N stretch), 1465 (C-H
deform), sym., asym S(=O)2 stretch (1164, 1-(4-Chloro-benzenesulfonyl)-5-(3,4-
1
1389). H NMR (δ ppm, DMSO): 1.91-1.96 dimethoxy-phenyl)-3-naphthalen-1-yl-4,5-
(dd, Jab: 17.56 Hz, Jax: 3.50 Hz, 1H, Ha), dihydro-1H-pyrazole (5i)
3.29-3.48 (dd, Jab: 4.01 Hz, Jbx: 17.23 Hz,
IR (cm-1): 3345 (N-H stretch), 3056 (C-H
1H, Hb), 3.66-3.84 (dd, Jax: 3.75 Hz, Jbx: Aromatic), 1577 (C=N stretch), 1462 (C-H
16.54 Hz, 1H, Hx), 7.00-7.77 (m, 12H, Ar). deform), 116570, 1362 (sym., asym S(=O)2
1
13C NMR (DMSO, ppm): 39.0 (CH2 pyrazo- stretch). H NMR (δ ppm, DMSO): 1.97-
line), 42.5 (CH pyrazoline), 125.8-131.2 1.98 (dd, Jab: 17.22 Hz, Jax: 3.52 Hz, 1H, Ha),
133

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3.39-3.47 (dd, Jab: 3.87 Hz, Jbx: 16.73 Hz, 1-(4-Chloro-benzenesulfonyl)-3-naphthalen-
1H, Hb), 3.54-3.69 (dd, Jax: 3.18 Hz, Jbx: 1-yl-5-thiophen-2-yl-4,5-dihydro-1H-
17.26 Hz, 1H, Hx), 3.80-3.94 (m, 6H, me- pyrazole (5l)
thyl), 6.78-7.64 (m, 14H, Ar). 13C NMR
IR (cm-1): 3292 (N-H stretch), 3047 (C-H
(DMSO, ppm): 39.7 (CH2 pyrazoline), 42.5 Aromatic), 1581 (C=N stretch), 1509 (C-H
(CH pyrazoline), 61.7 (2CH3), 113.7-132.5 deform), 1177, 1322 (sym., asym S(=O)2
1
(14CH Ar), 130.8-137.2 (7C Ar), 159.3 (C stretch). H NMR (δ ppm, DMSO): 2.08-
pyrazoline). MS (m/z): 507 (M+, 50 %). 2.09 (dd, Jab: 17.48 Hz, Jax: 2.99 Hz, 1H, Ha),
Anal. Calcd. for C27H23ClN2O4S: C, 63.96; 3.10-3.18 (dd, Jab: 3.74 Hz, Jbx: 17.04 Hz,
H, 4.57; N, 5.53. Found: C, 64.07; H, 4.61; 1H, Hb), 3.83-3.86 (dd, Jax: 3.26 Hz, Jbx:
N, 5.46.
16.36 Hz, 1H, Hx), 6.60-7.92 (m, 14H, Ar).
13C NMR (DMSO, ppm): 40.6 (CH2 pyrazo-
line), 46.1 (CH pyrazoline), 118.5-129.2
(14CH Ar), 137.8-148.1 (6C Ar), 161.5 (C
pyrazoline). MS (m/z): 463 (M+, 50 %).
Anal. Calcd. for C23H17ClN2O2S2: C, 60.98;
H, 3.78; N, 6.18. Found: C, 61.06; H, 3.76;
N, 6.21.
1-(4-Chloro-benzenesulfonyl)-5-(4-chloro-
phenyl)-3-naphthalen-1-yl-4,5-dihydro-1H-
pyrazole (5j)
IR (cm-1): 3266 (N-H stretch), 3011 (C-H
Aromatic), 1570 (C=N stretch), 1495 (C-H
deform), 1166, 1362 (sym., asym S(=O)2
1
stretch). H NMR (δ ppm, DMSO): 2.15-
2.19 (dd, Jab: 16.68 Hz, Jax: 3.27 Hz, 1H, Ha), 2-[1-(4-Chloro-benzenesulfonyl)-5-(3,4-
3.83-3.88 (dd, Jab: 3.95 Hz, Jbx: 17.10 Hz, dimethoxy-phenyl)-4,5-dihydro-1H-pyrazol-
1H, Hb), 3.50-3.67 (dd, Jax: 4.12 Hz, Jbx: 3-yl]-pyridine (5q)
16.97 Hz, 1H, Hx), 6.90-7.73 (m, 14H, Ar).
IR (cm-1): 3321 (N-H stretch), 3084 (C-H
13C NMR (DMSO, ppm): 39.2 (CH2 pyrazo- Aromatic), 1624 (C=N stretch), 1466 (C-H
line), 46.4 (CH pyrazoline), 124.2-129.0 deform), 1170, 1337 (sym., asym S(=O)2
1
(14CH Ar), 128.5-136.1 (7C benzene), 158.7 stretch). H NMR (δ ppm, DMSO): 1.89-
(C pyrazoline). MS (m/z): 481 (M+, 50 %). 1.91 (dd, Jab: 15.62 Hz, Jax: 3.17 Hz, 1H, Ha),
Anal. Calcd. for C25H18Cl2N2O2S: C, 62.37; 3.33-3.39 (dd, Jab: 3.74 Hz, Jbx: 17.11 Hz,
H, 3.77; N, 5.82. Found: C, 62.49; H, 3.80; 1H, Hb), 3.65-3.80 (dd, Jax: 3.54 Hz, Jbx:
N, 5.78.
16.91 Hz, 1H, Hx), 3.73-3.94 (m, 6H, me-
thyl), 6.97-8.21 (m, 11H, Ar). 13C NMR
(DMSO, ppm): 40.2 (CH2 pyrazoline), 45.7
(CH pyrazoline), 49.5 (6C, CH3), 114.9-
135.8 (11CH Ar), 143.4-152.8 (6C benzene),
161.9 (C pyrazoline). MS (m/z): 458 (M+,
30 %). Anal. Calcd. for C22H20ClN3O4S: C,
57.70; H, 4.40; N, 9.18. Found: C, 57.64; H,
4.45; N, 9.14.
1-(4-Chloro-benzenesulfonyl)-5-furan-2-yl-
3-naphthalen-1-yl-4,5-dihydro-1H-pyrazole
(5k)
IR (cm-1): 3290 (N-H stretch), 3050 (C-H
Aromatic), 1635 (C=N stretch), 1469 (C-H
deform), 1166, 1355 (sym., asym S(=O)2
1
stretch). H 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, 2-[1-(4-Chloro-benzenesulfonyl)-5-(4-
1H, Hb), 4.88-5.21 (dd, Jax: 3.28 Hz, Jbx: chloro-phenyl)-4,5-dihydro-1H-pyrazol-3-
17.46 Hz, 1H, Hx), 6.80-6.93 (d, 2H, Ar), yl]-pyridine (5r)
7.43-7.54 (m, 4H, Ar), 7.66-7.85 (m, 7H,
IR (cm-1): 3421 (N-H stretch), 3091 (C-H
Ar). 13C NMR (DMSO, ppm): 50.7 (CH2 py- Aromatic), 1616 (C=N stretch), 1471 (C-H
razoline), 77.2 (CH pyrazoline), 124.4-126.9 deform), 1170,2 1383 (sym., asym S(=O)2
1
(2CH furan), 129.0-131.3 (7CH naphtha- stretch). H NMR (δ ppm, DMSO): 1.91-
lene), 133.7-138.2 (4CH benzene), 159.4 (C 1.94 (dd, Jab: 17.36 Hz, Jax: 3.21 Hz, 1H, Ha),
pyrazoline). MS (m/z): 437 (M+, 50 %), 438 3.64-3.48 (dd, Jab: 4.12 Hz, Jbx: 17.44 Hz,
(30 %). Anal. Calcd. for C23H17ClN2O3S: C, 1H, Hb), 3.69-3.85 (dd, Jax: 3.28 Hz, Jbx:
63.23; H, 3.92; N, 6.41. Found: C, 63.26; H, 16.55 Hz, 1H, Hx), 7.29-8.69 (m, 12H, Ar).
3.97; N, 6.40.
13C NMR (DMSO, ppm): 40.2 (CH2 pyrazo-
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Received: October 10, 2017, accepted: January 15, 2018, published: January 19, 2018
line), 44.5 (CH pyrazoline), 124.6-149.2 using behavioral in vivo tests in mice model,
(12CH Ar), 137.1-139.4 (2C benzene), 154.2 such as forced swim test (FST) and tail sus-
(C pyridine), 160.7 (C pyrazoline). MS pension test, (TST) as given by Porsolt
(m/z): 432 (M+, 55%). Anal. Calcd. for (1981) and Willner and Mitchell (2002).
C20H15Cl2N3O2S: C, 55.56; H, 3.50; N, 9.72.
-
Porsolt’s behavioral despair or FST
In FST, the state of despair can be mini-
2-[1-(4-Chloro-benzenesulfonyl)-5-thiophen- mized by different therapeutically effective
Found: C, 55.60; H, 3.51; N, 9.68.
2-yl-4,5-dihydro-1H-pyrazol-3-yl]-pyridine
antidepressants (Porsolt et al., 1977; Vogel,
2002). The duration of immobility in ani-
(5t)
IR (cm-1): 3387 (N-H stretch), 3083 (C-H mals, produced by the test compounds, was
Aromatic), 1612 (C=N stretch), 1468 (C-H measured by known procedures (Tripathi et
deform), 1167, 1389 (sym., asym S(=O)2 al., 2016; Upadhyay et al., 2017).
1
stretch). H NMR (δ ppm, DMSO): 1.90-
-
Tail suspension test (TST)
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 (DMSO, ppm): 38.6 (CH2 pyrazo-
line), 43.2 (C pyrazoline), 115.6-140.3
(12CH benzene), 144.9-157.1 (4C Ar), 161.3
(C pyrazoline). MS (m/z): 403 (M+, 25 %).
Anal. Calcd. for C18H14ClN3O2S2: C, 53.53;
H, 3.49; N, 10.40. Found: C, 53.49; H, 3.53;
N, 10.37.
TST is another well known method (Ste-
ru et al., 1985; Vogel, 2002), employed to
evaluate the antidepressant potential of the
test compounds. In this test, the duration of
immobility was measured by known proce-
dures (Tripathi et al., 2016; Upadhyay et al.,
2017).
Anti-anxiety activity
The maze model was used to evaluate an-
ti-anxiety potential of the test compounds,
which selectively identified the anxiolytic
(open arm exploration time increased and
time spent in closed arms decreased) and
Biological evaluation
Study animals
The study protocols were authenticated anxiogenic drugs (Vogel, 2002).
by the Institutional Animal Ethics Commit-
tee (IAEC) with the protocol number
BBDNIIT/IAEC/009/2014.
Elevated plus-maze test
The elevated plus-maze was used to de-
termine anxiety-related behavior, measured
by the extent to which the mouse avoids vis-
iting the open arm of the maze (Lister, 1987;
Pellow et al., 1985). After one hour of oral
administration of the test compound, obser-
vations (i.e. time spent in closed arm and to-
tal number of the arm entries) were recorded
during the 6 minute test duration by known
procedures (Tripathi et al., 2016; Upadhyay
et al., 2017).
Animal house, Faculty of Pharmacy,
BBDNIIT, Lucknow, U.P., India provided
animals (male albino mice) for the in-vivo
study which were treated humanely and
maintained under standard conditions of
temperature (26 ± 2 ºC), percent humidity
(55 ± 5), light and dark cycles and free ac-
cess to food and water.
Study design
The studies were performed as per re-
ported procedures (Tripathi et al., 2016;
Upadhyay et al., 2017). The detailed descrip-
tion of the groups and respective doses are
given in Table 2.
Antidepressant activity
The antidepressant potential of the syn-
thesized derivatives (5a-5t) was evaluated
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EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
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Table 2: Data showing antidepressant, anti-anxiety and neurotoxicity studies of the synthesized 2-pyrazoline derivatives (5a-5t)
Compounds
Group
Number
Doses
(mg/kg
b.w.)
Antidepressant Activitya
Anti-anxiety Activityb
Neurotoxicity Studies
Rotarod Testc
Actophotometer Testd
(Mean Counts)
Duration of Im-
mobility in FST
(sec) (Mean±SD) (sec) (Mean±SD)
Duration of Im-
mobility in TST
Number of En-
tries in Closed
Arms
Time Spent in Before After
Before
Dose
After Dose (Af-
ter 1h)
Closed Arms
(sec)
Dose
Dose
(After
1h)
(Mean±SD)
(Mean±SD)
291.83
277.33
284.17
317.17
440.17
275.50
446.67
277.33
470.33
286.17
275.50
284.17
477.83
286.17
446.67
298.00
486.67
286.17
485.50
286.17
298.00
284.50
284.17
317.17
430.67
277.67
473.33
272.33
461.17
283.50
270.83
258.33
517.50
301.00
445.67
297.00
488.67
281.83
482.67
282.83
1
50
100
50
125.17±8.93
89.50±11.11
79.33±12.39
85.50±10.50
82.67±6.41
177.83±17.27
174.00±19.97
107.67±27.44
101.67±15.71
136.50±18.29
122.83±10.03
201.17±12.54
155.33±9.73
97.50±30.25
76.50±20.69
149.67±8.45
150.50±8.31
93.00±11.17
149.17±42.10
133.33±23.85
107.67±17.96
129.50±37.25
132.17±11.32
65.83±13.79
37.83±10.25
10.83±3.66
14.00±2.53
12.33±2.58
15.67±2.94
6.83±1.47
7.67±2.94
8.83±3.06
9.33±4.18
5.17±2.32
6.50±1.87
6.50±1.05
9.00±2.37
3.67±1.63
5.17±2.32
6.50±3.27
8.67±3.27
8.00±2.28
9.50±1.87
7.00±1.79
8.83±2.04
162.00±21.54
126.33±11.50
143.83±11.67
102.83±9.58
194.33±13.59
188.33±15.68
146.00±14.21
138.67±11.94
196.33±13.43
211.83±15.25
273.17±12.58
275.17±26.50
198.50±19.38
255.67±28.39
253.17±15.18
208.17±24.26
222.17±16.80
193.67±20.22
205.17±14.02
175.17±24.00
0/6
1/6
0/6
0/6
0/6
0/6
1/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
2/6
0/6
0/6
0/6
1/6
0/6
0/6
1/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
5a
5b
5c
5d
5f
2
3
4
100
50
5
6
100
50
68.50±15.73
124.33±9.71
97.67±14.19
105.17±13.85
87.83±18.79
104.17±15.56
99.50±14.64
155.00±11.64
101.67±12.26
94.33±14.18
73.33±25.40
112.50±19.15
84.67±13.34
58.00±7.97
7
8
100
50
9
10
11
12
13
14
15
16
17
18
19
20
100
50
5g
5h
5i
100
50
100
50
100
50
5j
100
50
5k
100
23.00±6.20
136

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10, 2017, accepted: January 15, 2018, published: January 19, 2018
Compounds
Group
Number
Doses
(mg/kg
b.w.)
Antidepressant Activitya
Anti-anxiety Activityb
Neurotoxicity Studies
Rotarod Testc
Actophotometer Testd
(Mean Counts)
Duration of Im-
mobility in FST
(sec) (Mean±SD) (sec) (Mean±SD)
Duration of Im-
mobility in TST
Number of En-
tries in Closed
Arms
Time Spent in Before After
Before
Dose
After Dose (Af-
ter 1h)
Closed Arms
(sec)
Dose
Dose
(After
1h)
(Mean±SD)
(Mean±SD)
275.50
284.17
286.17
275.50
284.17
279.17
281.67
277.33
269.33
282.50
288.33
274.67
279.17
276.00
272.83
287.00
21
22
23
24
25
26
27
28
50
100
50
59.67±9.93
43.50±8.04
129.17±17.93
54.83±15.88
107.50±17.90
76.67±6.59
7.67±3.20
9.17±2.32
8.83±2.32
12.50±2.07
2.50±2.43
4.00±3.03
7.33±2.25
8.50±2.81
164.83±14.74
137.83±10.46
214.17±15.22
170.33±18.00
225.17±22.44
233.33±22.65
274.17±19.03
257.67±34.37
1/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
1/6
0/6
0/6
1/6
0/6
0/6
0/6
0/6
5l
73.00±17.13
70.50±16.96
158.33±9.07
103.83±10.11
107.50±8.87
79.67±11.48
5q
5r
5t
100
50
114.50±13.13
100.83±11.75
101.17±14.97
76.67±6.59
100
50
100
Control
(CMC)
29
0.5%
179.67± 18.67
219.00±17.56
0.83±0.75
281.67±41.09
0/6
0/6
410.33
394.17
Standard
drug
30
10
29.33±8.43
60.33±9.33
---
---
0/6
1/6
399.50
404.83
(Imipramine)
Standard
drug
31
2
---
---
9.33±3.08
177.33±45.18
0/6
0/6
228.00
239.67
( Diazepam)
Bold data represents the most active compounds in the series.
n=6 (Number of animals tested at each dose level); p < 0.05.
Control: Carboxy methyl cellulose (CMC, 0.5 % suspension).
Standard: Imipramine (10 mg/kg, b.w.) for antidepressant activity and Diazepam (2 mg/kg, b.w.) for anti-anxiety activity.
a The reduction in time of immobility in FST and TST are an established way to evaluate effectiveness of antidepressants.
b The number of entries is increased in anxiolytic agents and decrease in anxiogenic agents and the amount of time spent in closed arms is
decreased in anxiolytic agents and increase in anxiogenic agents.
c Neurotoxicity was evaluated in Rotarod test before dosing and after 1 hour of dosing (number of animals exhibiting toxicity/number of animals tested).
d Neurotoxicity recorded in actophotometer test (Counts recorded in 10 minutes duration)
137

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
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Neurotoxicity study
compounds, two freely accessible computer
This study was used to evaluate the effect programs (LAZAR and OSIRIS Property
of the compounds on the CNS, employing explorer) were employed. Among them,
various behavioral tests, such as rotarod, LAZAR provided a generic tool for predict-
open-field/actophotometer, turning on flat ing complex toxicological end points (like
surface and inclined plane tests in mice long-term toxicity, reproductive toxicity and
model (Vogel, 2002; Parasuraman, 2011).
carcinogenicity). OSIRIS program calculated
various drug-related properties of chemical
structures and risks of untoward effects,
Neuromuscular coordination study
The effect of the compounds on motor which are considered as an indication of
coordination, where relaxation of skeletal drug-conform behavior (Klebe, 2000).
muscle is produced, was examined, as per
method given by Dunham and Miya in 1957, Statistical analysis
with slight modification (Vogel et al., 2002).
Statistical analysis was carried out using
Graph Pad Prism 5.0 (Graph Pad Software,
San Diego, CA). Experimental results are
expressed as mean±SD, analyzed by one-
way ANOVA followed by Dunnett’s test for
the possible significance (P<0.05) between
various groups.
Locomotor activity (actophotometer test)
Locomotor activities of the animals were
used as an index of their mental alertness,
which is affected (increased or decreased) by
majority of the CNS acting drugs (Dhingra
and Goyal, 2008; Tripathi et al., 2016;
Upadhyay et al., 2017).
RESULTS AND DISCUSSION
Acute toxicity study
A total of fourteen 1,3,5-trisubstituted 2-
The consequences (changes in skin and pyrazoline derivatives (5a-5t) were prepared
fur, behavior patterns, convulsions, tremors through Claisen-Schmidt condensation, fol-
and death) of a single dose on a particular lowed by heterocyclization and substitution
animal species was determined by acute tox- with 4-chlorobenzenesulfonylchloride using
icity testing. In this study, acute oral toxicity both, conventional and MAOS methods. The
(LD50) of two most active final derivatives microwave assisted procedures were devel-
(5b and 5k) was performed as per guidelines oped for the first time to synthesize the final
laid by Organization for Economic Coopera- 1,3,5-trisubstituted-2-pyrazoline derivatives.
tion and Development (OECD) guideline No The research outcomes suggested that almost
423 “Acute Oral Toxicity - Acute Toxic all the derivatives synthesized by this tech-
Class Method” using known procedures nique were obtained at a faster rate and in a
(OECD, 2001).
better synthetic yield in comparison to con-
ventional procedures. The prepared deriva-
tives were analyzed by various physico-
Computational studies
Molecular docking simulations were chemical (Table 1) and spectral techniques
used to predict binding affinity and binding and results comply with the proposal. The IR
orientations of the synthesized compounds to spectra reflect some characteristic absorption
the MAO-A protein (PDB ID: 2Z5X), with bands in the corresponding regions to C=N
the help of GLIDE program (Schrödinger, str (1509-1612 cm-1), N-H str (3449-3107
LLC, 2014), using known procedures (Tripa- cm-1) and C-H deform (1431-1354 cm-1). In
thi et al., 2016; Upadhyay et al., 2017). the third step derivatives, a characteristic
QikProp module of Schrödinger software peak of sulfonyl group was also observed in
1
program was successfully employed for in the IR spectra. H-NMR spectra showed that
silico prediction of ADME properties of the two dissimilar methylene protons (Ha/Hb)
synthesized derivatives. Furthermore, for in were visible at δ 2.92–3.38 ppm, 3.70–3.93
silico toxicity prediction of the synthesized which coupled themselves and with the me-
138

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10,2017, accepted: January 15, 2018, published: January 19, 2018
thine proton (Hx) at δ 6.67–7.03 in vicinity. evaluated doses. The pharmacological ac-
The other values were in congruence with tions of the prepared analogs were observed
the corresponding aliphatic and aromatic in a dose dependent manner, as the magni-
protons.
tude of the effects increased at higher tested
The pharmacological results (Table 2 and doses (100 mg/kg b.w.). The structure activi-
Figure 2) demonstrated that number of en- ty relationship studies established that C-3
tries in closed and open arms, in the elevated naphthalen-1-yl substitution and C-5 furan-
plus maze test, increased significantly with a 2-yl substitution at 2-pyrazoline nucleus
lesser closed arm exploration time (Figure 2a were crucial for the antidepressant activity
and 2b) for Compound 5b and Compound 5k (5k). However, a polar substitution of 4-
showed the best antidepressant action (Fig- hydroxyphenyl group at 3rd position (5b) was
ure 2c and 2d) in FST and TST models at the essential in eliciting anxiolytic activity.
Figure 2: (a) Anti-anxiety activity (Number of entries in closed arms in Elevated Plus Maze Test);
(b) Anti-anxiety activity (Time spent in closed arms in Elevated Plus Maze Test).
139

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
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Figure 2 (cont.): (c) Antidepressant activity (Forced Swim Test); (d) Antidepressant activity (Tail Sus-
pension Test)
MAOs are considered as an important protein. The most stable conformation of lig-
biological target to develop drugs against and-protein complex and the interaction
certain mental disorders, such as depression studies of the most active compounds, 5b
and anxiety. It has been also established that and 5k at the MAO-A protein binding pocket
the 2-pyrazoline derivatives possess excel- have been depicted in Figure 3 and 4. Dock-
lent affinity towards MAO isoforms, as re- ing studies inferred that Ala 68, Tyr69 and
ported in previous literatures. Docking stud- Phe352 are some important residues interact-
ies allowed to gain some structural inputs ing at the MAO-A binding pocket. It was ev-
towards binding characteristics of the pre- ident that at 2-pyrazoline nucleus, N1 p-
pared derivatives with the MAO-A target chlorobenzenesulfonyl substitution proved to
140

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10,2017, accepted: January 15, 2018, published: January 19, 2018
be very useful and all the compounds having out. Additionally, most potent derivatives
this substitution showed better activity than were evaluated for their acute toxicity at the
the N1 unsubstituted pyrazolines (Tripathi et corresponding doses. None of them showed
al., 2016). The presence of sulfonyl group at any changes in behavioral pattern, convul-
N1 position of 2-pyrazoline nucleus evi- sions, tremors, skin changes and death
denced H-bonding interaction between sul- throughout the 14 days acute toxicity studies.
fonyl oxygen and Ala68 and Tyr69 residues Also, encouraging in silico pharmacokinetic
at the MAO-A binding pocket. It was properties (Table 3) were observed. Moreo-
demonstrated in previous works that ligands ver, the screened compounds were not liable
having such type of hydrogen bond interac- to cause carcinogenicity, mutagenicity, re-
tions are well placed in the aromatic cage of productive toxicity, acute toxicity and irri-
the MAO protein possessing C5 furyl/ sub- tancy. Therefore, they were regarded to be
stituted phenyl ring and N1-benzenesulfonyl safe as was corroborated by the computa-
ring of 2-pyrazoline nucleus. The naph- tional programs such as LAZAR and OSIRIS
thyl/4-chlorophenyl rings showed, impera- (Table 4).
tive pi-pi stacking interactions with Phe352
backbone residue. It was also evident that
most of the interactions of PDB co-crystal
ligand 2Z5X were conserved in compounds
5b and 5k. Furthermore, the predicted bind-
ing affinity (Glide gscores) of the prepared
analogs complemented well with the in vivo
anti-anxiety and antidepressant activities da-
ta.
The synthesized compounds were also
tested for their probable neurotoxicological
effects, such as motor coordination (rotarod
test) and locomotor activity (actophotometer
test). The obtained results suggested that
these derivatives were completely free from
severe neurotoxicity (motor co-ordinations
and locomotor disturbances) threats at the
evaluated doses (Table 2). In Rotarod test,
the mean fall-off time of most of the mice
was greater than 180 seconds, and hence
these compounds may not affect the motor
coordination of the animals. Also, the mean
counts in actophotometer test in pre-dose
studies, and after 1 hour of dosing, were not
significantly different and therefore, any
probability of CNS stimulating or depressing
effects of the tested compounds was ruled
CONCLUSION
This study concludes that the synthesized
2-pyrazoline analogs possess excellent to
good antidepressant and anti-anxiety poten-
tial, as evaluated using various in vivo meth-
ods. The presence of C-3 naphthalen-1-yl
substitution and C-5 furan-2-yl substitution
at 2-pyrazoline nucleus was decisive for the
antidepressant activity (5k). However, a po-
lar substitution of 4-hydroxyphenyl group at
3rd position (5b) was essential in eliciting
anxiolytic activity. Nearly all the compounds
were completely free from any neurotoxic
indications, with a complementary pharma-
cokinetic behavior as predicted by in silico
methods. Molecular docking experiments as-
certained some imperative interactions of
these compounds with the target protein,
playing a pivotal role in neuropharmacology.
Thus, in a nutshell, the synthesized 2-
pyrazoline derivatives may prove their worth
in the treatment and management of certain
mental disorders, possibly through MAO-A
inhibition.
141

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Received: October 10,2017, accepted: January 15, 2018, published: January 19, 2018
Figure 3: Ligand receptor interaction diagram of compound 5b 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.
142

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10,2017, accepted: January 15, 2018, published: January 19, 2018
Figure 4: Ligand receptor interaction diagram of compound 5k 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.
143

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10,2017, accepted: January 15, 2018, published: January 19, 2018
Table 3: In silico prediction of binding affinity (Glide gscore) and ADME parameters of the synthesized 1,3,5-trisubstituted-2-pyrazoline derivatives (5a-5t)
Com-
pounds
Glide
gscore
#Sta MW
rs
Volume
PSA
SASA
Donar- Ac-
HB cptH
CNS QPlog QlogP QPlog QPP
Site of
metab
%
Human
Oral
Viola-
tions of
Rule of
BB
o/w
Khsa
Caco
B
absorp- Five
tion
5a
-7.36
-8.91
-8.75
-8.10
-7.73
-8.82
-7.80
-8.78
-9.06
-9.24
-8.36
-7.20
-8.59
-8.12
-6.89
---
0
0
0
472.94 1272.98 86.63 666.85
447.34 1184.44 73.71 639.41
402.85 1094.53 82.24 602.32
418.91 1130.25 74.61 622.66
465.78 1205.86 51.17 651.08
421.30 1115.91 59.71 613.96
437.36 1151.77 52.08 634.43
507.00 1389.36 64.30 720.45
481.40 1294.00 51.34 690.76
436.91 1204.01 59.87 652.93
452.97 1240.41 52.23 673.58
457.93 1240.78 76.47 652.37
432.32 1152.67 63.55 624.66
403.90 1099.01 64.46 608.64
1
7.75
-1
0
0
-0.80
-0.53
-0.68
-0.60
0.20
3.70
0.35
0.50
0.16
0.35
0.56
0.17
0.41
0.61
0.82
0.42
0.66
-0.09 1384.40
0.14 1315.15
-0.02 1263.71
0.222
-1.5
582.26
557.41
520.10
5
3
4
4
2
3
3
4
2
3
3
5
3
4
3
100
100
93.64
100
0
5b
5c
5d
5f
1
1
1
6.25
6.75
6.25
5.50
6.00
5.50
7.00
5.50
6.00
5.50
8.00
6.50
6.50
1.75
2 to
4.08
3.09
3.65
5.09
4.04
4.66
5.16
0
0
0
0
0
538.82
1
0
1
1836.33
1713.80
1775.53
2166.91
2146.71
1972.42
2055.46
100
1
5g
5h
5i
0
0
1
0.05
100
0
1
0
0
0
1
0
0.14
-0.21
100
90.92
100
0
2
5j
1
0
1
0.078 5.579
1
5k
1
0
0
0
0
0
0
1
-1
0
-0.09
0.01
-0.36
-0.10
-0.17
0.18
-3.0
4.52
5.14
3.46
3.92
3.48
3.11
-2.0
100
100
100
0
1
0
5l
5q
5r
0
0
0
1
100
0
5t
0
0
0
0
100
100
0
0
2Z5X
Std.
values
212.25
130 to
725
733.39
500 to
2000
33.50 381.35
840.62
0-5
7 to
200
300 to
1000
0 to 6
-2 to
+2
<25poor 1 to 8
>500
great
<20%
low,
>80%
high
Maxi-
mum is
4
20
to 1.2 to 6.5 to 1.5
#stars: Number of property or descriptor values that fall outside the 95 % range of similar values for known drugs; Volume: Total solvent accessible volume in
cubic angstrom using a probe with 1.4 Ǻ radius; PSA: Van der Waals polar surface area of nitrogen and oxygen atoms; SASA: Total solvent accessible surface
area in sqare angstrom using a probe with 1.4 Ǻ radius; donarHB: Hydrogen bond donar; accptHB: Hydrogen bond acceptor; CNS: Predicted central nervous
system activity at -2 (inactive) to +2 (active) scale; QPlogBB: Predicted brain/blood partition coefficient; QlogPo/w: Predicted octanol-water partition coefficient.
QPlogKhsa: Prediction of binding to human serum albumin; QPPCaco: Predicted apparent Caco-2 cell permeability in nm/sec; metab: Number of likely meta-
bolic reactions; Number of violations of Lipinski’s rule of five.
144

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10,2017, accepted: January 15, 2018, published: January 19, 2018
Table 4: In silico toxicity prediction data of the synthesized 1,3,5-trisubstituted -2-pyrazoline derivatives (5a-5t)
Compounds Toxicity prediction
OSIRIS PROPERTY EXPLORER
LAZAR
Mutagenic
Tumorigenic
Irritant
Reproductive
effect
Maximum rec- Mutagenicity Acute toxicity
Carcinogenic
potency
ommended
daily dose
(mmol)
LC50 (mmol)
5a
5b
5c
5d
5f
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
4.23e+00
-
-
-
-
-
-
-
-
-
-
-
-
5.51e+00
1.38e+01
2.31e+01
2.61e+01
8.78e+00
1.01e+01
9.11e+00
4.10e+00
7.05e+00
8.28e+00
1.03e+01
3.03e+00
-
-
4.62e+00
1.44e+01
1.50e+01
6.86e+00
1.25e+01
1.30e+01
4.52e+00
8.67e+00
1.47e+01
1.37e+01
1.02e+01
-
-
-
-
-
-
5g
5h
5i
-
-
-
-
+
+
+
+
-
+
-
5j
5k
5l
-
+
-
5q
5r
5t
-
-
-
-
-
4.24e+01
2.16e+02
-
5.34e+00
7.31e+00
-
+
-
-
-
-
No risk: (-); Medium risk: (+); High risk: (++)
145

EXCLI Journal 2018;17:126-148 – ISSN 1611-2156
Received: October 10,2017, accepted: January 15, 2018, published: January 19, 2018
Chimenti F, Carradori S, Secci D, Bolasco A, Bizzarri
B, Chimenti P, et al. Synthesis and inhibitory activity
against human monoamine oxidase of N1-thio-
carbamoyl-3,5-di(hetero)aryl-4,5-dihydro-(1H)-pyra-
zole derivatives. Eur J Med Chem. 2010;45:800-4.
Acknowledgements
The authors would like to thank 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.
We would extend our sincere gratitude 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 soft-
ware facility has been made available at the
host institute and the technical support
team/application scientists of Schrödinger
Inc. for their help during implementation of
the project.
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