Thiazolidine-4-one clubbed pyrazoles hybrids: Potent α-amylase and α-glucosidase inhibitors with NLO properties

Article abstract of DOI:10.1002/jhet.3882

Molecular hybrids based on thiazolidin-4-one and pyrazolyl pharmacophore (THZP) as new antidiabetic agents were synthesized. Two sets of signals came into view in ¹H NMR of THZP8-THZP14 exhibited the presence of a configurational isomeric mixture of 2E,5Z (38.24%-41.58%) and 2Z,5Z isomers (58.42%-61.76%), which was further endorsed by density functional theory (DFT) studies. All the compounds exhibit promising nonlinear optical properties (NLO). Further, the biological potential of THZPs was explored in terms of α-amylase and α-glucosidase inhibition. DFT-based descriptors were calculated to describe the reactivity, and a relationship was developed with biological activities. THZP9 and THZP14 showed remarkable inhibition of α-amylase and α-glucosidase with IC₅₀ 9.90μM and 4.84μM, respectively, as compared with standard drug acarbose.

Full text of DOI:10.1002/jhet.3882

Received: 17 April 2019
DOI: 10.1002/jhet.3882
Revised: 26 November 2019
Accepted: 19 December 2019
A R T I C L E
Thiazolidine-4-one clubbed pyrazoles hybrids: Potent
α-amylase and α-glucosidase inhibitors with NLO
properties
Parvin Kumar1
| Meenakshi Duhan1 | Jayant Sindhu2 | Kulbir Kadyan1
|
Sangeeta Saini1 | Neeraj Panihar3
1Department of Chemistry, Kurukshetra
Abstract
University, Kurukshetra, India
2Department of Chemistry, COBS&H CCS
Haryana Agricultural University, Hisar,
India
3Department of Pharmaceutical Science,
G.J.U.S.T, Hisar, India
Molecular hybrids based on thiazolidin-4-one and pyrazolyl pharmacophore
(THZP) as new antidiabetic agents were synthesized. Two sets of signals came
into view in 1H NMR of THZP8-THZP14 exhibited the presence of a configu-
rational isomeric mixture of 2E,5Z (38.24%-41.58%) and 2Z,5Z isomers
(58.42%-61.76%), which was further endorsed by density functional theory
(DFT) studies. All the compounds exhibit promising nonlinear optical proper-
ties (NLO). Further, the biological potential of THZPs was explored in terms
of α-amylase and α-glucosidase inhibition. DFT-based descriptors were calcu-
lated to describe the reactivity, and a relationship was developed with biologi-
cal activities. THZP9 and THZP14 showed remarkable inhibition of
α-amylase and α-glucosidase with IC50 9.90μM and 4.84μM, respectively, as
compared with standard drug acarbose.
Correspondence
Parvin Kumara, Department of
Chemistry, Kurukshetra University,
Kurukshetra 136119, India.
Email: parvinchem@kuk.ac.in;
parvinjangra@gmail.com
1 | INTRODUCTION
absorption after a meal by inhibiting these two enzymes
is an influential method for the alleviation and treatment
Medicinal chemists are putting serious efforts to control
diabetes-related mortality; nevertheless, this disease is
still alarming and also increasing each year.[1–3] The life
sustainability of hyperglycemic patients depend exten-
sively on blood glucose level and thus regulating its level
can be considered as a real challenge in the scientific
arena.[4] The prolonged hyperglycemic condition is a
prime mortality factor that partially results from its effect
on structural and functional aspect of vital proteins.[5] It
is presumed that hyperglycemia enhances the creation of
free radicals and reactive oxygen species leading to oxida-
tive tissue damage, which further leads to various compli-
cations such as neuropathy,[6,7] nephropathy,[8,9]
retinopathy,[10,11] and cardiovascular disorders.[12,13]
The postprandial hyperglycemic condition in patients
with diabetes is because of hydrolysis of dietary carbohy-
drates, which is governed by two enzymes, ie,
α-glucosidase and α-amylase.[14,15] Suspension of glucose
of type 2 diabetes mellitus (T2DM). Furthermore, the
complications of modified immune responses and meta-
bolic disorders can be controlled by regulating the activ-
ity of α-amylase and α-glucosidase.[16] Currently,
voglibose and acarbose are frequently used as
α-glucosidase and α-amylase inhibitors to control post-
prandial hyperglycemic condition.[17] The effectiveness of
these drugs for the treatment of T2DM is repressed due
to various side effects such as flatulence, abdominal dis-
tension, and diarrhoea associated with their exposure.[18]
The side effects associated with marketed drugs is a sig-
nificant mode to devise novel inhibitors that are more
effective and safer for the treatment of T2DM.[19,20]
Thiazolidine-4-one,
a
privileged pharmacophore,
came into existence for its role as an antihyperglycemic
agent and is a part of a number of antidiabetic
drugs.[21,22] Thiazolidin-4-one has been emerged as a very
persuasive scaffold because of its clinical significance and
J Heterocycl Chem. 2019;1–15.
wileyonlinelibrary.com/journal/jhet
© 2019 Wiley Periodicals, Inc.
1

2
KUMAR ET AL.
widespread pharmacological activities associated with
it.[23–30] Similarly, another significant class of compound,
named pyrazole has a broad range of biological activities
such as anti-inflammatory, antifungal,[31] antioxidant,[32]
antitumor,[33] antihypertensive, antibacterial,[34] antican-
cer activity,[35] and antidiabetic activities[36] associated
with it.
(petroleum ether: ethylacetate [60:40, v/v]). Upon com-
pletion, the contents of the reaction mass were cooled at
room temperature. The solid thus formed was filtered
and washed with absolute ethanol to afford thiazolidine-
4-one clubbed pyrazole-based molecular hybrids
(THZP1-THZP14) in 71% to 88% yield (Scheme 1,
Table 1).
Persisting our interest in the design and development
of biologically active heterocyclic compounds[22,24,37–41]
and novel inhibitor of α-amylase[22] we, herein, report
the design and synthesis of a hybrid scaffold having
thiazolidin-4-one and pyrazole in a single matrix.
1H NMR and density functional theory (DFT) studies
explored the isomerization in the synthesized com-
pounds. All the newly synthesized molecular hybrids
were screened in vitro for their inhibitory potential
against α-amylase and α-glucosidase. The docking study
of the most active compound was performed to investi-
gate the interaction with the binding site of α-amylase
and α-glucosidase.
The structure of all newly synthesized molecular
hybrids (THZP1-THZP14) was ascertained by using vari-
ous spectral techniques like infrared (IR), H NMR, and
1
mass. In IR spectrum, N H stretching and C O
stretching band of the thiazolidinone ring appeared at
3050 to 3127 cm−1 and 1700 to 1720 cm−1, respectively.
The stretching of exocyclic C C bond present on the
thiazolidine-4-one ring resulted into an absorption band
in the range 1646 to 1691 cm−1. Two configurational iso-
mers in terms of E and Z at the imino form of
2-arylimino-4-thiazolidinone were very well-cited in the
literature.[43] In case of 3a, single set of signals was
observed, however, for 3b, two signal sets were observed
for CH2, NH, OCH3, and aryl protons as shown in
(Figure 1).
2 | RESULT AND DISCUSSION
2.1 | Chemistry
From the above-discussed facts, it was considered that
when an electron-withdrawing group such as NO2 was
present on the phenyl ring, a single set of signals was
observed because of the existence of only one configura-
tional isomer, ie, 2Z. However, when the electron-
withdrawing group was replaced by electron-donating
group ( OCH3), two sets of signals were observed for
two configurational isomers due to restricted rotation
about the imine (C N) linkage, ie, 2Z and 2E. The pres-
ence of two isomeric forms was also observed in case of
the target molecular hybrids (THZP8-THZP14) synthe-
sized from 3b.
The following synthetic methodology achieved the syn-
thesis of molecular hybrids (THZP1-THZP14) based on
thiazolidine-4-one and pyrazole. The key reactant 2-(p-
arylimino)thiazolidin-4-one (3), required for the synthesis
of
molecular
hybrids
(THZP1-THZP14),
was
prepared by condensing 4-substituted arylthiourea
(2) with ethyl 2-bromoacetate in glacial acetic acid using
sodium acetate as a base. The compound 3 thus formed
was condensed with 3-(aryl)-1-phenyl-1H-pyrazole-
4-carbaldehyde[42] (4a-4g) in refluxing ethanol using
piperidine as a base for 10 to 12 hours. The reaction
was monitored by thin-layer chromatography (TLC)
To understand the configurational isomerism of
1
molecular hybrids (THZP1-THZP14) by H NMR, com-
pound 2-(4-methoxyphenylimino)-5-([1-phenyl-3-p-tolyl-
1H-pyrazol-4-yl]methylene)thiazolidin-4-one (THZP8)
SCHEME 1 Synthesis of thiazolidine-4-one clubbed pyrazole based molecular hybrids (THZP1-THZP14)

KUMAR ET AL.
3
1
was taken as a test case. In H NMR of THZP8, peaks at
(δ 3.78-3.77) and (δ 8.66-8.57) were observed because of
OMe and Pyr H protons, respectively. Aromatic pro-
tons of 2E,5Z and 2Z,5Z isomers were also associated
with two signal sets for THZP8 (Figure 2). When the
1H NMR of the test compound was recorded in
trifluoroacetic acid (TFA), the doubling of resonating sig-
nals disappeared, and it clearly shows that the diastereo-
meric mixture is dynamic not static (Figure 2). The
configurational isomerism is also confirmed by
2D-1H NMR and HRMS (see Data S1, Figure S20-S23).
products (THZP8-THZP14). Similarly, in case of com-
pounds (THZP1-THZP14) the δ value observed for H7
was also in agreement with the Z isomer.
Therefore, these compounds exist only in one config-
urational isomer 2Z,5Z. The existence of two isomeric
forms in terms of C N configurational isomers was
supported by the presence of two signal sets when the
spectra were recorded in DMSO which is also conferring
with the literature.[43,44] The predominance of isomer
was assessed by integrating the singlets observed for pro-
tons related with methoxy ( OCH3) and pyrazole at
25ꢀC. The 2Z,5Z isomer was found to be predominant
with a percentage of 58.47% to 60.59%. However, the rela-
tive percentage observed for 2E,5Z isomer was 39.41% to
41.17%. (Table S1).
1
Resonating signals at δ 7.46-7.37 ppm in H NMR was
associated with the olefinic proton (H7). The chemical
shift value observed for this proton was higher than
expected for 5E isomer and was mainly because of aniso-
tropic effect of C O present in the vicinity of this pro-
ton.[43] Further, a proton present in the vicinity of sulfur
would resonate at lower δ value due to less deshielding
effect exerted by sulfur, which was also not observed in
present case.[44] Therefore, the possibility of isomeriza-
tion at fifth position was ruled out and only two isomers
are possible becuase of C N isomerization in condensed
2.2 | Configurational studies using DFT
The molecular geometry of all the newly synthesized
compounds (THZP1-THZP14) was optimized with DFT.
B3LYP exchange-correlation functional[45,46] along with
6-311G basic sets were used through Gaussian09 package.
1
Initially, analysis of H NMR reveals the possibility of
two isomeric forms for compound 3b and one for 3a.
Moreover, after its condensation with an aldehyde at fifth
position, two more isomeric form results due to C C
TABLE 1 Synthesis of thiazolidine-4-one clubbed pyrazole
based molecular hybrids (THZP1-THZP14)
S. No.
1.
Compound Code
THZP1
R
R1
Yield, %
85
1
isomerization at fifth position. However, the H NMR of
NO2
OCH3
F
the compound THZP8 reveals the presence of only two
isomeric forms which are possible only because of C N
isomerization. The two isomeric forms were then con-
structed with full energy optimizations performed by
using same correlation functional. No imaginary frequen-
cies were observed on their respective potential energy
surfaces, which ensure the energy minima for all isomers.
Out of these, the isomer with (2Z,5Z) configuration is of
lowest energy and is more stable. The comparative analy-
sis of the total energy (Etotal) for (2Z,5Z) and (2E,5Z) of
THZP1 and THZP8 was done and the results were tabu-
lated in Table 2. The Erel observed for (2E,5Z) isomer was
3.75 kcal/mol for THZP1 and 11.15 kcal/mol than
(2E,5Z) for THZP8, respectively, which suggests configu-
rational barrier between two isomers of THZP8 because
of comparatively high energy gap between them. The
2.
THZP2
NO2
81
3.
THZP3
NO2
Cl
83
4.
THZP4
NO2
Br
75
5.
THZP5
NO2
CH3
H
82
6.
THZP6
NO2
77
7.
THZP7
NO2
NO2
CH3
OCH3
Br
88
8.
THZP8
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
80
9.
THZP9
75
10.
11.
12.
13.
14.
THZP10
THZP11
THZP12
THZP13
THZP14
71
F
78
Cl
85
H
79
NO2
83
FIGURE 1 Two signal sets assigned for 3a
and 3b in 1H NMR [Color figure can be viewed
at wileyonlinelibrary.com]

4
KUMAR ET AL.
FIGURE 2 Configurational isomerism in THZP8 with the characteristic peak in its 1H NMR in DMSO-d6 and trifluoroacetic acid
(TFA) [Color figure can be viewed at wileyonlinelibrary.com]
geometry optimization was then performed using 2Z,5Z
configuration for all compounds and their optimized
geometry with energy and dipole moment are tabulated
in Table S2.
THZP8 are shown in Figure 3. DFT-based global reac-
tivity descriptors, ie, chemical hardness (η), chemical
potential (μ), electrophilicity index (ω), and electronega-
tivity (χ) have been quite extensively studied to predict
the bioprofile of a molecule.[48–50] The chemical hard-
ness of a system is an important parameter for
accessing the stability and reactivity of a system and is
represented by η = (ELUMO-EHOMO)/2. This descriptor is
used as a measure of resistance to change in the elec-
tronic distribution or charge on a molecule.[51] Electro-
negativity, another global reactivity descriptor
represented by χ = −(EHOMO + ELUMO)/2, is defined as
2.3 | Electrostatic results
The physicochemical behaviour, energy gap, and energy
associated with a compound can be best defined using
energy of molecular orbitals. The eigen value associated
with these frontier molecular orbitals was then assessed
to furnish the chemical reactivity and biological potency
of a molecule.[47] HOMO and LUMO for THZP1 and
the electron attracting ability of an atom in
a
molecule.[52]

KUMAR ET AL.
5
TABLE 2 Configurational barrier in terms of relative energies for two isomeric forms of compound THZP1 and THZP8
Isomeric
form
Erel
Kcal/mol
Erel
Kcal/mol
Isomers of THZP1
Etotal (au)
Isomers of THZP8
Etotal (au)
2Z,5Z
−1974.85458 0.0
−1809.68703 0.0
2E,5Z
−1974.84860 3.75
−1809.66925 11.15
FIGURE 3 HOMO-LUMO for compound (A) THZP1 and (B) THZP8 [Color figure can be viewed at wileyonlinelibrary.com]
Further, the negative of electronegativity is known as
chemical and is defined as
potential[53]
and lowest with THZP1 (4.62 eV) among the compounds
of series I with a difference of 0.41 eV between two
extreme values. However, this difference became 0.59 eV
in series II with the highest hardness value of 4.56 eV
corresponds to THZP14 (4.56 eV) and the lowest with
THZP9 (3.97 eV). From the above discussion and on the
basis of principle of maximum hardness, it has been rev-
ealed that compounds THZP7 and THZP14 are more
reactive than THZP1 and THZP9. Highest electron
attracting capabilities were observed for THZP7 and
THZP14 with electronegativity values of 2.51 and
2.28 eV, respectively, in their respective series.
Further, high value of electrophilicity index (ω) asso-
ciated with both compounds reflects their strong electro-
philic abilities. The relative change between extreme
values of electrophilicity index (ω) (ωmax-ωmin/ ωmax) was
smaller for series I (0.07) as compared with series II
(0.13). This higher value of relative change associated
with series II reflects its strong capacity to accept elec-
trons than series I with more sensitivity towards specific
substituents (Table 3).
μ = (EHOMO + ELUMO)/2. The global electrophilic nature
associated with a molecule can be assessed in a relative
range using electrophilicity index (ω). This descriptor was
introduced by Parr and is calculated using the electronic
chemical potential and chemical hardness and given as
ω = μ2/2η.[54] All the values of global reactivity descrip-
tors calculated for all the newly synthesized compounds
(THZP1-THZP14) are summarized in Table 3.
These molecular hybrids (THZP1-THZP8) are cate-
gorized into two series according to the structural homol-
ogy: both series I and II consists of seven compounds
each. Series I (THZP1-THZP8), where aryl group of
thiazolidine-4-one is substituted with nitro group, differs
from series II (THZP8-THZP14) in terms of substituent
present on the aryl group of thiazolidine-4-one. Com-
pounds substituted with methoxy group on the aryl group
of thiazolidine-4-one are categorized under series
II. From Table 3, it has been revealed that the highest
value of hardness was associated with THZP7 (5.03 eV)

6
KUMAR ET AL.
Molecules with a π-conjugated system may result in
parameters like dipole moment (μ), polarizability (α), and
its first-order component (β) calculated for all the com-
pounds (THZP1-THZP14) are listed in Table 4. The
values associated with α and β were reported in
e.s.u. Conversion factor 0.1482 × 10−24 e.s.u for Δα and
8.6393 × 10−33 e.s.u for βtot were used for conversion of
values observed in atomic units (au). The calculated
values were then compared with the standard prototype,
ie, urea.
asymmetric polarisation because of the presence of elec-
tron releasing and withdrawing substituents. Materials
accompanying high NLO properties can be applied in
optoelectronic and nonlinear optics. In order to investi-
gate the NLO properties associated with compounds
(THZP1-THZP14), DFT method was employed to calcu-
late the polarizabilities and hyperpolarizabilities associ-
ated with compounds (THZP1-THZP14). The various
TABLE 3 Electrostatic results for compounds THZP1-THZP14
Global
Global
LUMO Chemical
Compounds HOMO LUMO HOMO-1 +1
Hardness
η = (−μ)
Electrophilicity
Index (ω) = μ2/2η
Softness
(s) s = 1/η
Potential, μ
−4.62
−4.84
−4.86
−4.84
−4.71
−4.76
−5.03
−4.00
−3.97
−4.12
−4.12
−4.14
−4.03
−4.56
THZP1
THZP2
THZP3
THZP4
THZP5
THZP6
THZP7
THZP8
THZP9
THZP10
THZP11
THZP12
THZP13
THZP14
−6.13
−6.48
−6.52
−6.48
−6.30
−6.38
−6.73
−5.78
−5.74
−5.89
−5.89
−5.91
−5.82
−6.02
−3.10
−3.19
−3.21
−3.20
−3.12
−3.14
−3.33
−2.22
−2.20
−2.34
−2.34
−2.36
−2.25
−3.11
−6.61
−7.06
−7.07
−6.98
−6.84
−6.97
−7.28
−6.14
−5.99
−6.29
−6.29
−6.33
−6.25
−2.49
−2.53
−2.66
−2.69
−2.67
−2.55
−2.57
−3.25
−1.27
−1.22
−1.50
−1.47
−1.53
−1.31
−6.53
4.62
4.84
4.86
4.84
4.71
4.76
5.03
4.00
3.97
4.11
4.12
4.14
4.03
4.56
2.31
2.42
2.43
2.42
2.35
2.38
2.52
2.00
1.98
2.06
2.06
2.07
2.02
2.28
0.22
0.21
0.21
0.21
0.21
0.21
0.20
0.25
0.25
0.24
0.24
0.24
0.25
0.22
TABLE 4 NLO properties associated with compounds (THZP1-THZP14)
Compound
THZP1
THZP2
THZP3
THZP4
THZP5
THZP6
THZP7
THZP8
THZP9
THZP10
THZP11
THZP12
THZP13
THZP14
Dipole Moment, μ
β
tot (au)
β
tot x 10−30 (e.s.u)
<α>(au)
−223.31
−229.29
−239.12
−242.96
−220.41
−215.05
−256.02
−189.29
−190.69
−206.70
−197.68
−206.02
−183.38
−221.71
<Δα> (au)
56.26
<Δα> x 10−24 (e.s.u)
6.36
2.93
2.74
3.03
5.32
4.71
3.91
3.76
3.44
6.74
6.81
7.37
4.31
11.10
986.92
389.32
368.66
979.41
706.86
586.26
256.88
312.19
240.35
286.42
617.96
730.13
400.55
1207.05
8.52
3.36
3.18
8.46
6.10
5.06
2.21
2.69
2.07
2.47
5.33
6.30
3.46
10.42
8.34
14.74
15.52
14.56
8.59
9.48
21.64
7.42
9.67
5.38
5.08
5.26
7.38
8.45
99.47
104.72
98.23
57.98
63.99
146.00
50.06
65.27
36.28
34.29
35.47
49.79
57.03

KUMAR ET AL.
7
TABLE 5 Inhibition profile of compounds (THZP1-THZP14)
against α-amylase and α-glucosidase
All the compounds showed many fold NLO properties
when compared with urea (0.15 × 10−30) (Table 4). It has
been revealed from Table 4 that compounds substituted
with electron-releasing group at one end and electron-
withdrawing at the other are associated with high
second-order nonlinear optical properties. Among all,
compound THZP14 showed highest βtot (e.s.u) value of
10.42 × 10−30, which is nearly 70 times more than urea,
α-Amylase
α-Glucosidase
Compound
THZP1
IC50 (μM)
14.49
43.30
51.04
25.31
65.02
13.79
14.49
28.01
9.90
SE
2.47
IC50 (μM)
17.31
40.43
13.26
16.73
89.15
92.32
32.20
8.60
SE
1.50
1.40
2.32
1.75
1.30
1.37
1.15
1.33
1.23
1.25
1.66
1.49
1.63
1.19
1.38
THZP2
1.25
1.63
1.26
1.39
2.16
1.41
1.74
1.53
1.10
1.32
3.82
1.44
1.37
1.36
THZP3
followed by THZP1 with βtot (e.s.u) value of 8.52 × 10−30
.
THZP4
The pattern of substitution plays an important role here.
Compounds substituted with nitro group on pyrazole
ring and methoxy group on phenyl ring attached with
thiazolidine-4-one (THZP14) showed highest βtot (e.s.u)
value. However, a decrease in the value of βtot (e.s.u)
from 10.42 × 10−30 to 8.52 × 10−30 was observed when
the pattern of substitution was reversed. Above findings
suggests that the asymmetric polarization resulted to a
maximum extent when electron density flows in a direc-
tion from thiazolidine-4-one to pyrazole ring. Moreover,
compounds with substitution of similar nature are also
associated with low value of βtot (e.s.u), ie, THZP7 and
THZP9.
THZP5
THZP6
THZP7
THZP8
THZP9
54.46
28.08
23.34
56.70
14.86
4.48
THZP10
THZP11
THZP12
THZP13
THZP14
Acarbose
38.10
13.80
10.24
11.45
16.15
47.86
10.53
2.4 | Biological studies
2.4.2 | Molecular docking studies
2.4.1 | Enzyme inhibition studies
Recently, the computer-assisted drug design (CADD) has
been accepted as a successful methodology of drug design
and discovery to understand the structural design of a
drug candidate. It is quite fast, cost-effective, and result-
oriented fruitful in silico technique.[55,56] The active site
of a target protein can be assessed using molecular dock-
ing to explore the probable binding modes of a drug. The
molecular docking studies were performed with
AutoDock Vina software to predict the probable mode of
binding for most potent compounds THZP9 and
THZP14. Docking simulation of THZP9 and THZP14
was performed with the active site of Aspergillus oryzae
from α-amylase (PDB ID: 7TAA) and α-glucosidase from
Saccharomyces cerevisiae to establish the binding confor-
mation and interactions responsible for their activity. The
most active compounds THZP9 and THZP14 were
sketched using ChemAxon software and these were
changed into 3D structures using the MMFF94 force
field.
The aim behind design and synthesis of thiazolidine-
4-one clubbed pyrazole would be incomplete without
exploring their biological potential. Towards this, screen-
ing was done for evaluating the inhibitory potential of
molecular hybrids against α-amylase and α-glucosidase
enzyme. The inhibition showed by all the hybrids was
also compared with standard drug acarbose. The IC50
values were determined for all the newly synthesized
molecular hybrids against α-amylase and α-glucosidase.
As shown in Table 5, the IC50 varied from 9.90μM to
65.02μM for α-amylase and from 4.48μM to 92.32μM for
α-glucosidase, respectively. Significant inhibition was
observed for all the compounds when compared with
standard. In case of α-amylase, all compounds except 5e
(IC50 = 65.02μM) showed improved IC50 value when
compared with standard drug acarbose. However, in case
of α-glucosidase, compounds THZP14, THZP13,
THZP8, and THZP3 showed comparable inhibition with
IC50 value of 4.48μM, 14.86μM, 8.60μM, and 13.26μM,
respectively. In case of α-amylase, the most potent com-
pound was THZP9 with IC50 = 9.90μM. However, in case
of α-glucosidase, the most potent was THZP14 with
IC50 = 4.48μM. The inhibition profile of the all the com-
pounds and their comparison with standard drug was
shown in Figure 4.
2.4.3 | Docking analysis of α-amylase
Binding pose with the highest binding affinity for docked
conformation of THZP9 is shown in Figure 5. It has been
revealed from Figure 5 that various interactions in terms

8
KUMAR ET AL.
FIGURE 4 Graphical
representation of IC50 (μM) of
compounds (THZP1-THZP14) against
α-amylase and α-glucosidase [Color
figure can be viewed at
wileyonlinelibrary.com]
FIGURE 5 2D and 3D dock pose of α-amylase with THZP9 [Color figure can be viewed at wileyonlinelibrary.com]
of hydrogen bonding, hydrophobic, electrostatic, and
π-sulfur interactions are mainly responsible for anchoring
of the compound THZP9 in active site of α-amylase. The
oxygen atom of methoxy group and carbonyl group form
the conventional hydrogen bonding with the Gln35,
Tyr79, Trp83, and His210 amino acid. The oxygen atom
act as acceptor and these amino acids act as donor. The
carbon-hydrogen bond was found between the carbon of
methoxy group and Glu230 and Tyr75. The electrostatic
interaction, ie, π-anion was created between the phenyl
ring and Asp168 & Glu230 amino acid. The hydrophobic
interactions such as π-π stacked, π-π T-shaped, and
π-alkyl were also found (Table S3). In case of α-amylase,
Glu230 and Asp206 are the residues responsible for the
catalytic activity in hydrolytic reactions[57] and the bind-
ing of THZP9 to these residues is probably the cause of
inhibition in case of α-amylase. Further, the co-
crystallized ligand along with THZP9 in the active site of
α-amylase is shown in Figure S1.
2.4.4 | Docking analysis of α-glucosidase
The docking study was performed after the preparation of a
homology model for α-glucosidase because of unavailability
of the crystal structure for α-glucosidase of S. cerevisiae
(strain ATCC 204508 / S288c). The α-glucosidase from
S. cerevisiae [EC: 3.2.1.20] (CAS Number 9001-42-7) was
purchased from Sigma Aldrich. The gene information
shows that it contains MAL12 (853209) and MAL32
(852602) of baker yeast. The primary sequence of
α-glucosidase for S. cerevisiae was taken from UniProtKB

KUMAR ET AL.
9
(Access code P53341 for MAL12, UniRef100_P53341, and
P38158 for MAL32, UniRef100_P38158) and BLAST was
used to search the template against the PDB. The PDB
3AXH showed 72% identity and 85% similarity with the tar-
get enzyme α-glucosidase and was used as a template for
homology modelling. Then, a homology model was pre-
pared using SWISS-MODEL and checked using
PROCHECK.[58] The result retrieved from PROCHECK in
terms of Ramachandran plot revealed that in final 3D struc-
ture 89.0% of residues are present in most favoured regions
(Figure S2). The stereochemical parameter of the main
chain and side chain is given in Table S4. All the stereo-
chemical parameters of the main chain were found inside
the main region. The graphical representation of stereo-
chemical parameter of the main chain and side chain is
given in Figure S3-S4. The prepared PDB was aligned with
PDB:3AXH using Pymol (Figure S5). The active site of
α-glucosidase[59] was docked with THZP14 using the Auto
Dock Vina.[60] Then, docked pose was analyzed using dis-
covery studio R2 client.[61]
Six hydrogen bonds, three conventional hydrogen
bonds, two carbon-hydrogen bonds, and one π-donor
hydrogen bond were identified for the most active com-
pound THZP14 (Figure 6). The conventional hydrogen
bonding was found between N H and active site of
α-glucosidase (Glu276 & Asp 349 amino acids), whereas
His-245 amino acid was involved in conventional hydro-
gen bond with oxygen of nitro group. The C H bonding
was found between the carbon of methoxy group and
Asp68 & Gln181 amino acid. The N-phenyl ring of
pyrazole moiety formed the π-donor hydrogen bond with
Arg 312. The aromatic ring of imine moiety was involved
in π-anionic interaction with another active pocket of
α-glucosidase Asp 214 and Arg439 amino acids (Table S5).
Docking studies showed that compound THZP14 was
entangled in the active pocket of enzyme with six hydro-
gen bonds, seven hydrophobic, two electrostatic, and two
other interactions. Therefore, the enzymatic action of
α-glucosidase was inhibited through these interactions in
a cooperative fashion.
3 | EXPERIMENTAL
3.1 | Material and methods
1
Spectral analysis in terms of IR, H NMR, and mass was
done to elucidate the structure of all the newly synthe-
sized compounds. The progress of the reaction was moni-
tored using precoated silica gel aluminium plates
(60 F254) purchased from MERCK. Open glass capillary
tubes were used to determine uncorrected melting points.
In IR absorption spectra, the values are expressed as νmax
cm−1 and were obtained using Perkin Elmer FTIR spec-
1
trophotometer. H NMR spectral analysis was performed
in DMSO-d6 using tetramethylsilane as an internal stan-
dard. All the spectra were recorded at 400 and 500 MHZ
on Bruker (Avance-II). The δ and J values are expressed
in ppm and Hz, respectively. The 13C NMR spectra were
not witnessed because of poor solubility of compounds in
FIGURE 6 2D and 3D-Representation of α-glucosidase with THZP14 [Color figure can be viewed at wileyonlinelibrary.com]

10
KUMAR ET AL.
DMSO-d6 (see Data S1, Figure S24-S37). The chemicals
used in the synthesis were procured from local supplier
and are of Sigma-Aldrich and MERCK. Waters Micro-
mass Q-Tof was used to record mass spectrum.
Arylthiourea and substituted pyrazolyl carbaldehydes
were prepared using reported procedure.[22,42]
J = 8.8 Hz, 1H), 6.99-7.01(d, J = 8.8 Hz, 1H), 6.90-6.87
(m, 2H), 3.93, 3.86 (2s, 2H, CH2), 3.77, 3.76 (2s,
3H, OCH3).
3.4.3 | 5-((3-[4-Methoxyphenyl]-1-phenyl-
1H-pyrazol-4-yl)methylene)-
2-(4-nitrophenylimino) thiazolidin-4-one
(THZP1)
3.2 | A general method for the synthesis
of 2-substituted thiazolidin-4-one (3)[22]
Yield: 85%; mp >300ꢀC; IR (vmax cm−1, KBr): 3117
(N H lactam), 1697 (C O lactam), 1659 (C C), 1582
(C N), Ar NO2 1335 (Sym), 1504 (Asym); 1H NMR
(δppm, 400 MHz, DMSO-d6, ppm): δ 8.59 (1H, s, H17),
8.27 (2H, d, J = 9.2, H10/H12), 7.94 (2H, d, J = 8.0, H28/
H32), 7.60-7.50 (7H, m, H23/H27, H9/H13, H29/H31, H7),
7.39 (1H, t, J = 7.4, H30), 7.15-7.11 (2H, m, H24/H26),
3.85 (3H, s, -OCH3); Anal. Calc for C26H19N5O4S: C,
62.77; H, 3.85; N, 14.08; Found: C, 62.71; H,
3.82; N, 14.06.
A
mixture of arylthiourea (1.00 mmol), ethyl
bromoacetate (1.00 mmol), and sodium acetate
(2.0 mmol) in glacial acetic acid (10 mL) was heated
under reflux in a 50-mL round bottom flask. After com-
pletion of the reaction (monitored by TLC), the content
of the reaction was poured in a beaker containing ice and
the solid thus obtained was filtered and recrystallized
from ethanol.
3.3 | General method for the synthesis of
5-((3-(aryl)-1-phenyl-1H-pyrazol-4-yl)
methylene)-2-(p-arylimino)thiazolidin-
4-one (THZP1-THZP14)[22]
3.4.4 | 5-((3-[4-Fluorophenyl]-1-phenyl-
1H-pyrazol-4-yl)methylene)-
2-(4-nitrophenylimino) thiazolidin-4-one
(THZP2)
A condensation reaction of 2-arylimino-thiazolidine-
4-ones (3) (0.50 mmol) was attempted with substituted
pyrazole-4-carbaldehydes (4a-4g) (0.50 mmol) in absolute
ethanol using piperidine (0.50 mmol) as base. The con-
tent of the reaction was stirred for 8 hours at 60ꢀC in a
100-mL round bottom flask. After completion of the reac-
tion, the mixture was allowed to cool at room tempera-
ture and the precipitates thus formed were filtered and
washed with absolute ethanol to afford the final products
(THZP1-THZP14) in good to excellent yield.
Yield: 81%; mp >300ꢀC; IR (vmax cm−1, KBr): 3127 (N H
lactam), 1704 (C O lactam), 1666 (C C), 1582 (C N),
Ar NO2 1335 (Sym), 1504 (Asym); 1H NMR (δppm
,
400 MHz, DMSO-d6): δ 8.47 (1H, s, H17), 8.20 (2H, d,
J = 10.8, H10/H12), 7.89 (2H, d, J = 8.0, H28/H32),
7.68-7.665 (2H, m, H23/H27), 7.52-7.45 (5H, m, H9/H13,
H29/H31, H7), 7.37-7.30 (3H, m, H30, H24/H26); Anal. Calc
for C25H16FN5O3S: C, 61.85; H, 3.32; N, 14.43; Found: C,
61.81; H, 3.29; N, 14.41.
3.4 | Spectral data
3.4.5 | 5-((3-[4-Chlorophenyl]-1-phenyl-
1H-pyrazol-4-yl)methylene)-
2-(4-nitrophenylimino) thiazolidin-4-one
(THZP3)
3.4.1 | 2-(4-Nitrophenylimino)
thiazolidin-4-one (3a)
Yield: 85%; mp 167-170ꢀC; 1H NMR (δppm, 500 MHz,
DMSO-d6): δ 11.64 (s, 1H, NH), 8.41-8.43 (d, J = 10 Hz,
2H), 7.64-766 (d, J = 10 Hz, 2H), 4.27 (s, 2H, CH2).
Yield: 83%; mp >300ꢀC; IR (vmax cm−1, KBr): 31.24
(N H lactam), 1744 (C O lactam), 1697 (C C), 1582
(C N), Ar NO2 1335 (Sym), 1504 (Asym); 1H NMR
(δppm, 400 MHz, DMSO-d6) δ 12.31 (1H, s, NH), 8.35
(1H, s, H17), 8.09 (2H, d, J = 8.8, H10/H12), 7.73 (2H, d,
J = 8.0, H28/H32), 7.47 (2H, d, J = 8.4, H9/H13),
7.43-7.29 (5H, m, H23/H27, H29/H31, H30), 7.21-7.17 (2H,
m, H24/H26), 7.06 (1H, s, H7); Anal. Calc for
C25H16ClN5O3S: C, 59.82; H, 3.21; N, 13.95; Found: C,
59.78; H, 3.19; N, 13.91.
3.4.2 | 2-(4-Methoxyphenylimino)
thiazolidin-4-one (3b)
Yield: 85%; mp 157-160ꢀC; 1H NMR (δppm, 400 MHz,
DMSO-d6): δ 11.54, 10.94 (2s, NH), 7.63-7.61 (d,

KUMAR ET AL.
11
3.4.6 | 5-((3-[4-Bromophenyl]-1-phenyl-
1H-pyrazol-4-yl)methylene)-
2-(4-nitrophenylimino) thiazolidin-4-one
(THZP4)
Ar NO2 1342 (Sym), 1512 (Asym); 1H NMR (δppm
400 MHz, DMSO-d6): δ 8.54 (s, 1H, H17), 8.39 (d,
J = 8.8 Hz, 2H, H24/H26), 8.24 (d, J = 8.9 Hz, 2H, H10/
H12), 7.96-7.91 (m, 4H, H23/H27, H28/H32), 7.57-7.52 (m,
5H, H9/H13, H29/H31, H7), 7.41-7.38 (m, 1H, H30); Anal.
Calc. For C25H16N6O5S: C, 58.59; H, 3.15; N, 16.40;
Found: C, 58.55; H, 3.13; N, 16.38.
,
Yield: 75%; mp >300ꢀC; IR (vmax cm−1, KBr): 3124 (N H
lactam), 1744 (C O lactam), 1697 (C C), 1582 (C N),
Ar NO2 1335 (Sym), 1504 (Asym); 1H NMR (δppm
,
400 MHz, DMSO-d6): δ 12.42 (1H, s, NH), 8.56 (1H, s,
H17), 8.26 (2H, d, J = 9.2, H10/H12), 7.91 (2H, d, J = 7.6,
H28/H32), 7.73 (2H, d, J = 8.4, H9/H13), 7.58 (2H, d,
J = 8.4, H23/H27), 7.53-7.49 (4H, m, H29/H31, H24/H26),
7.39-7.35 (2H, m, H30, H7); Anal. Calc for
C25H16BrN5O3S: C, 54.95; H, 2.95; N, 12.82; Found: C,
54.94; H, 2.91; N, 12.76.
3.4.10 | 2-(4-Methoxyphenylimino)-
5-([1-phenyl-3-p-tolyl-1H-pyrazol-4-yl]
methylene) thiazolidin-4-one (THZP8)
Yield: 80%; mp 295-296ꢀC; IR (vmax cm−1, KBr): 3114
(N H lactam), 1736 (C O lactam), 1643 (C C), 1605
(C N); 1H NMR (δppm, 400 MHz, DMSO-d6): δ 8.66, 8.57
(2s, 41.17% (E), 58.82% (Z), 1H, H17), 7.97 (d, 2H,
J = 7.6 Hz, 41.53% (E), H28/H32), 7.94 (d, 2H, J = 7.6 Hz,
58.47% (Z), H28/H32), 7.71-7.51 (m, 6H, H9/H13, H23/H27,
H29/H31), 7.46-7.37 (m, 6H, H7, H30, H9/H13, H10/H12),
7.07-6.98 (m, 4H, H24/H26, H10/H12), 3.78, 3.77 (2s, 3H,
60.59% (Z), 39.41% (E), OCH3), 2.41 (s, 3H, CH3); Anal.
Calc. For C27H22N4O2S: C, 69.51; H, 4.75; N, 12.01;
Found: C, 69.45; H, 4.68; N, 11.97.
3.4.7 | 2-(4-Nitrophenylimino)-
5-([1-phenyl-3-p-tolyl-1H-pyrazol-4-yl]
methylene)thiazolidin-4-one (THZP5)
Yield: 82%; mp >300ꢀC; IR (vmax cm−1, KBr): 3124 (N H
lactam), 1697 (C O lactam), 1659 (C C), 1582 (C N),
Ar NO2 1335 (Sym), 1504 (Asym); 1H NMR (δppm
,
400 MHz, DMSO-d6): δ 12.44 (1H, s, NH), 8.51 (1H, s,
H17), 8.27 (2H, d, J = 8.8, H10/H12), 7.91 (2H, d, J = 8.0,
H28/H32), 7.55-7.49 (6H, m, H9/H13, H23/H27, H7, H30),
7.39-7.35 (4H, m, H29/H31, H24/H26), 2.42 (3H, s, CH3);
Anal. Calc for C26H19N5O3S: C, 64.85; H, 3.98; N, 14.54;
Found: C, 64.83; H, 3.91; N, 14.51.
3.4.11 | 5-((3-[4-Methoxyphenyl]-
1-phenyl-1H-pyrazol-4-yl)methylene)-
2-(4-methoxyphenyl imino)thiazolidin-
4-one (THZP9)
Yield: 75%; mp 299-300ꢀC; IR (vmax cm−1, KBr): 3070
(N H lactam), 1720 (C O lactam), 1651 (C C), 1612
(C N); 1H NMR (δppm, 500 MHz, DMSO-d6): δ 8.64, 8.56
(2s, 1H, 40.95% (E), 59.05% (Z), H17), 7.97 (d, J = 8.0 Hz,
2H, 41.51% (E), H28/H32), 7.93 (d, J = 8.0 Hz, 2H, 58.48%
(Z), H28/H32), 7.69-7.51 (m, 6H, H9/H13, H23/H27, H29/
H31), 7.45-7.36 (m, 2H, H7, H30), 7.15-7.12 (m, 2H, H24/
H26), 7.06-7.04 (d, J = 8.5 Hz, 2H, 39.69% (E), H10/H12),
7.00-6.97 (m, 4H, H9/H13, 60.31% (Z), H10/H12), 3.85 (s,
3H, OCH3), 3.78, 3.71 (2s, 3H, 61.76% (Z), 38.24% (E),
OCH3); Anal. Calc for C27H22N4O3S: C, 67.20; H, 4.60; N,
11.61; Found: C, 67.16; H, 4.58; N, 11.60.
3.4.8 | 5-([1,3-Diphenyl-1H-pyrazol-4-yl]
methylene)-2-(4-nitrophenylimino)
thiazolidin-4-one (THZP6)
Yield: 77%, mp >300ꢀC; IR (vmax cm−1, KBr): 3124 (N H
lactam), 1744 (C O lactam), 1666 (C C), 1582 (C N),
Ar NO2 1335 (Sym), 1504 (Asym); 1H NMR (δppm
,
400 MHz, DMSO-d6): δ 8.37 (s, 1H, H17), 8.23 (d,
J = 9.2 Hz, 2H, H10/H12), 7.84 (d, J = 8.4 Hz, 2H, H28/
H32), 7.61-7.44 (m, 8H, H23/H27, H9/H13, H29/H31, H7,
H30), 7.35-7.19 (m, 3H, H24/H26, H25); Anal. Calc. For
C25H17N5O3S: C, 64.23; H, 3.67; N, 14.98; Found: C,
64.22; H, 3.65; N, 14.92.
3.4.12 | 5-((3-[4-Bromophenyl]-1-phenyl-
1H-pyrazol-4-yl)methylene)-
2-(4-methoxyphenylimino) thiazolidin-
4-one (THZP10)
3.4.9 | 5-((3-[4-Nitrophenyl]-1-phenyl-1H-
pyrazol-4-yl)methylene)-
2-(4-nitrophenylimino) thiazolidin-4-one
(THZP7)
Yield: 71%; mp >300ꢀC; IR (vmax cm−1, KBr): 3047 (N H
lactam), 1713 (C O lactam), 1654 (C C), 1605 (C N); 1H
NMR (δppm, 500 MHz, DMSO-d6): δ 8.69, 8.61 (2s, 1H,
41.58% (E), 58.42% (Z), H17), 7.98 (d, J = 8.5 Hz, 2H,
Yield: 88%; mp >300ꢀC; IR (vmax cm−1, KBr): 3117 (N H
lactam), 1744 (C O lactam), 1705 (C C), 1682 (C N),

12
KUMAR ET AL.
41.55% (E), H28/H32), 7.94 (d, J = 8.0 Hz, 2H, 58.44% (Z),
H28/H32), 7.80-7.77 (m, 2H, H24/H26), 7.68-7.38 (m, 8H,
H23/H27, H29/H31, H7, H30, H9/H13), 7.04 (d, 2H,
J = 9.0 Hz, 39.13% (E), H10/H12), 7.00-6.96 (m, 4H, H9/H13,
60.86% (Z), H10/H12), 3.77, 3.76 (2s, 3H, 60.94% (Z), 39.06%
(E), OCH3); Anal. Calc for C26H19BrN4O2S: C, 58.76; H,
3.60; N, 10.54; Found: C, 58.73; H, 3.57; N, 10.45.
H24/H26, H25), 7.46-7.38 (m, 2H, H7, H30), 7.06-6.98 (m,
4H, H9/H13, H10/H12), 3.78, 3.77 (2s, 3H, 59.71% (Z),
40.28% (E), OCH3); Anal. Calc for C26H20N4O2S: C,
69.01; H, 4.45; N, 12.38; Found: C, 68.98; H, 4.40; N, 12.31.
3.4.16 | 2-(4-Methoxyphenylimino)-
5-((3-[4-nitrophenyl]-1-phenyl-1H-pyrazol-
4-yl)methylene) thiazolidin-4-one (THZP14)
3.4.13 | 5-((3-[4-Fluorophenyl]-1-phenyl-
1H-pyrazol-4-yl)methylene)-
2-(4-methoxyphenylimino) thiazolidin-
4-one (THZP11)
Yield: 83%; mp >300ꢀC; IR (vmax cm−1, KBr): 3117 (N H
lactam), 1716 (C O lactam), 1690 (C C), 1605 (C N);
1H NMR (δppm, 500 MHz, DMSO-d6): δ 8.76, 8.68 (2s, 1H,
40.86% (Z), 59.14% (E), H17), 8.42 (d, J = 9.5 Hz, 1H, H24/
H26), 8.02-7.93 (m, 4H, H28/H32, H23/H27), 7.71-7.36 (m,
6H, H9/H13, H29/H31, H7, H30), 7.01-6.95 (m, 4H, H9/H13,
H10/H12), 3.77 (s, 3H, OCH3); Anal. Calc for
C26H19N5O4S: C, 62.77; H, 3.85; N, 14.08; Found: C,
62.76; H, 3.86; N, 14.02.
Yield: 78%; mp >300ꢀC; IR (vmax cm−1, KBr): 3024 (N H
lactam), 1713 (C O lactam), 1643 (C C), 1605 (C N);
1H NMR (δppm, 500 MHz, DMSO-d6): δ 8.70, 8.61 (2s, 1H,
40.0% (E), 60.0% (Z), H17), 7.99 (d, J = 8.2 Hz, 2H, 39.27%
(E), H28/H32), 7.95 (d, J = 8.3 Hz, 2H, 60.73% (Z), H28/
H32), 7.72-6.97 (m, 12H, H10/H12, H9/H13, H24/H26, H7,
H30, H23/H27, H29/H31), 3.78, 3.77 (2s, 3H, 58.63% (Z),
41.43% (E), OCH3); Anal. Calc. For C26H19FN4O2S: C,
66.37; H, 4.07; N, 11.91; Found: C, 66.35; H,
4.01; N, 11.85.
3.5 | Enzyme inhibition assay
3.5.1 | Assay for α-amylase inhibition
The α-amylase inhibition study was done using reported
protocol with slight modifications.[62] Stock solutions for
all the compounds were prepared in DMSO by dissolving
1 mg of compound in 1 mL of solvent. Six different con-
centrations (3.125, 6.25, 12.5, 25, 50, 100 μg/mL) were
used to evaluate the inhibition potential against
α-amylase from A. oryzae. All the solutions required for
the inhibition studies were prepared according to already
reported procedure.[62] The absorbances were measured
at 650 nm using microplate reader.
3.4.14 | 5-((3-[4-Chlorophenyl]-1-phenyl-
1H-pyrazol-4-yl)methylene)-
2-(4-methoxyphenylimino) thiazolidin-
4-one (THZP12)
Yield: 85%; mp >300ꢀC; IR (vmax cm−1, KBr): 3072 (N H
lactam), 1713 (C O lactam), 1643 (C C), 1605 (C N); 1H
NMR (δppm, 500 MHz, DMSO-d6): δ 8.72, 8.63 (2s, 1H,
41.0% (E), 59.0% (Z), H17), 7.99 (d, J = 8.5 Hz, 2H, 40.90%
(E), H28/H32), 7.95 (d, J = 7.5 Hz, 2H, 59.09% (Z), H28/
H32), 7.70-6.95 (m, 12H, H23/H27, H24/H26, H29/H31, H7,
H30, H9/H13, H10/H12), 3.78, 3.71 (2s, 3H, 61.29% (Z),
38.71% (E), OCH3); Anal. Calc for C26H19ClN4O2S: C,
64.13; H, 3.93; N, 11.51; Found: C, 64.10; H, 3.90; N, 11.47.
3.5.2 | Assay for α-glucosidase inhibition
Chromogenic method with slight modification was used to
evaluate the α-glucosidase (obtained from S. cerevisiae)
inhibitory activities.[63] Six different concentrations (3.125,
6.25, 12.5, 25, 50, 100 μg/mL) were prepared for all the com-
pounds. All the solutions required for the inhibition studies
were prepared according to already reported procedure.[63]
The blank solution was devoid of α-glucosidase and the
standard drug acarbose was used as positive control. Experi-
ments were performed in triplicate and the absorbance was
measured at 450 nm using microplate. The enzyme inhibi-
tory rates of samples were calculated as follows:
3.4.15 | 5-([1,3-Diphenyl-1H-pyrazol-4-yl]
methylene)-2-(4-methoxyphenylimino)
thiazolidin-4-one (THZP13)
Yield: 79%; mp 293-295ꢀC; IR (vmax cm−1, KBr): 3047
(N H lactam), 1713 (C O lactam), 1643 (C C), 1605
1
(C N); H NMR (δppm, 500 MHz, DMSO-d6): δ 8.70, 8.62
(2s, 1H, 40.0% (E), 60.0% (Z), H17), 7.99 (d, J = 8.0 Hz, 2H,
41.06% (E), H28/H32), 7.96 (d, J = 8.0 Hz, 2H, 58.93% (Z),
H28/H32), 7.71-7.52 (m, 9H, H23/H27, H9/H13, H29/H31,
%Inhibition = ðControl−SampleÞ=Control × 100

KUMAR ET AL.
13
3.6 | Computational studies
3.6.1 | DFT studies
isomaltase in complex with isomaltose of S. cerevisiae
(strain ATCC 204508 / S288c) (PDB ID: 3AXH), which
have 72% identical and 85% similar sequence with
α-glucosidase of S. cerevisiae. Swiss-Model was used for
the sequence alignment and homology modelling,[72]
which was further evaluated using PROCHECK.[73]
Then, the most active compound THZP14 was docked
into the active site (Asp214, Glu276, Asp 349, and
Arg439) of prepared model of S. cerevisiae using the Auto
Dock Vina program.[71] Grid center was placed on the
active site. The centers and sizes of the grid box were as
All calculations have been performed using Gauss-
ian09[64] quantum-chemical package. The relative ther-
modynamic stability for (2Z,5Z) and (2E,5Z) isomer of
both the compounds (THZP1 and THZP8) was assessed
using the energy of the optimized structures for both the
isomers. The structure of all the compounds was opti-
mized using B3LYP[46] exchange-correlation functional
with 6-311G basis set.[65,66] The anisotropy of polarizabil-
ity Δα and its mean first order hyperpolarizability
<β > were calculated by the following equations[67] using
the x, y, z components (Equations 1 and 2).
follows:
center_x
=
−21.7738263108,
cen-
ter_y = −5.92333172777, center_z = −21.0706013836,
size_x = 20.7667725457, size_y = 20.3967525101, and
size_z = 25.0. The discovery studio 2016 client and
PyMol[74] were used for visualization of docking results.
sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
À
Á
À
Á
2
αxx −αyy 2 + αyy −αzz + ðαzz −αxxÞ
2
Δα =
ð1Þ
ð2Þ
2
4 | CONCLUSION
ꢂ
ꢀ
ꢁ
ꢀ
ꢁ
2
xxx + βxyy + βxzz 2 + βyyy + βyzz + βyxx
We have synthesized molecular hybrids based on
thiazolidin-4-one and pyrazolyl pharmacophore (THZP)
as new antidiabetic agents. Spectroscopic analyses (IR,
1H NMR, MS) were done to confirm the structures of all
the newly synthesized hybrids (THZP) The presence of
two sets of signals in 1H NMR of 3b and one set of signal
in 3a revealed the existence of two configurational iso-
mers (E and Z) in case of 3b. Two sets of signals were
come into view in 1H NMR of THZP8-THZP14 exhibited
the presence of a configurational isomeric mixture of
2E,5Z (38.24%-41.58%) and 2Z,5Z isomers (58.42%-
61.76%), which was further endorsed by DFT
studies. DFT-based global chemical descriptors were cal-
culated to describe the reactivity and to develop a
relationship with biological activities. All the compounds
(THZP1-THZP14) exhibit promising nonlinear optical
properties (NLO). Further, the biological potential of all
the synthesized compounds (THZP1-THZP8) was
explored in terms of α-amylase and α-glucosidase inhibi-
tion studies. Compounds THZP9 and THZP14 showed
remarkable inhibition of α-amylase and α-glucosidase
with IC50 9.90μM and 4.84μM, respectively, as compared
with standard drug acarbose (IC50 47.86μM for
α-amylase & 10.53μM for α-glucosidase). Docking studies
further supported the results of the activity.
βtot
=
β
ꢀ
ꢁ
2
1=2
+ βzzz + βzxx + βzyy
ꢁ
,
where αxx, αyy, and αzz represents the components of
polarizability and βx, βy, and βz are tensor components
of hyperpolarizability.
3.6.2 | Docking simulations
Marvin sketch was used for preparing an optimized 3D
structure of both compound THZP9 and THZP14. The pro-
tein data bank was assessed for the PDB structure of
α-amylase for A. oryzae (PDB ID: 7TAA) (http://www.rcsb.
org/pdb). The protein was prepared by using UCSF Chi-
mera 1.10[68] in which co-crystallized ligand and solvent
molecules were removed to avoid interference in binding
interactions. Missing side-chain gaps were filled using Dun
Brack Rotamer library.[69] Gasteiger charges were calculated
using AMBERf14SB and antechamber[70] and hydrogens
were added. The Docking studies were performed using
Auto Dock Vina 1.1.2.[71] Grid center with the following size
center_x = 40.1983719675, center_y = 37.596211689, cen-
ter_z
=
31.4482747318, size_x
=
21.9397670481,
size_y = 25.0, and size_z = 20.2076584074 were placed on
the active site. The results of docking studies were analyzed
in discovery studio 2016 client.[61]
The protein sequence for Baker's yeast α-glucosidase
(MAL12 & MAL32) was retrieved from UniProt (http://
www.uniprot.org). Homology model for S. cerevisiae
α-glucosidase was constructed using crystal structure of
ACKNOWLEDGMENT
M.D. thanks the Haryana State Council of Science and
Technology (HSCTC) for the award of research fellow-
ship. The authors also thank SAIF PU for spectral data.
ORCID
Parvin Kumar https://orcid.org/0000-0002-2635-6465

14
KUMAR ET AL.
[32] J. R. Badgujar, D. H. More, J. S. Meshram, Indian J Microbiol
2018, 58, 93.
REFERENCES
[1] N. Unwin, J. Shaw, P. Zimmet, K. Alberti, Diabetic med 2002,
19, 708.
[2] A. Accurso, R. K. Bernstein, A. Dahlqvist, B. Draznin,
R. D. Feinman, E. J. Fine, A. Gleed, D. B. Jacobs, G. Larson,
R. H. Lustig, Nutr metab 2008, 5, 9.
[33] H. Dai, S. Ge, J. Guo, M. Chen, Huang, J. Yang, S. Sun,
Y. Ling, Y. Shi, Eur J Med Chem 2018, 143, 1066.
[34] H. Liu, Z. L. Ren, W. Wang, J. X. Gong, M. J. Chu, Q. W. Ma,
J. C. Wang, X. H. Lv, Eur J Med Chem 2018, 157, 81.
[35] H. A. Elhady, R. El-Sayed, H. S. Al-nathali, Chem Cent J 2018,
12, 51.
[3] T. Tuomi, N. Santoro, S. Caprio, M. Cai, J. Weng, L. Groop,
Lancet 2014, 383, 1084.
[36] M. J. Naim, O. Alam, M. J. Alam, M. Q. Hassan, N. Siddiqui,
V. Naidu, M. I. Alam, Bioorg Chem 2018, 76, 98.
[37] P. Kumar, R. Bhatia, R. Khanna, A. Dalal, D. Kumar,
P. Surain, R. C. Kamboj, J Sulfur Chem 2017, 38, 585.
[38] P. Kumar, K. Kadyan, M. Duhan, J. Sindhu, V. Singh,
B. S. Saharan, Chem Cent J 2017, 11, 115.
[39] A. Kumar, A. Chawla, S. Jain, P. Kumar, S. Kumar, Med Chem
Res 2011, 20, 678.
[40] S. Kumar, Meenakshi, S. Kumar, P. Kumar, Med Chem Res
2013, 22, 433.
[41] P. Kumar, A. Kumar, J. Sindhu, S. Lal, Drug Res. 2018, 69, 159.
https://doi.org/10.1055/a-0652-5290.
[42] P. Kumar, S. Kumar, K. Husain, A. Kumar, Chin Chem Lett
2011, 22, 37.
[43] S. Ramsh, N. Smorygo, E. Khrabrova, A. Ginak, Chem Hetero-
cycl Com 1986, 22, 447.
[44] R. Ottana, R. Maccari, M. L. Barreca, G. Bruno, A. Rotondo,
A. Rossi, G. Chiricosta, R. D. Paola, L. Sautebin, S. Cuzzocrea,
Bioorg Med Chem 2005, 13, 4243.
[4] Control, D.; Group, C. T. R. N E J Med 1993, 329, 977.
[5] D. Daneman, Diabetes care 2001, 24, 801.
ꢀ
ꢀ
[6] I. Mišur, K. Žarkovic, A. Barada, L. Batelja, Z. Milicˇevic,
Z. Turk, Acta diabetol 2004, 41, 158.
[7] K. Sugimoto, M. Yasujima, S. Yagihashi, Curr pharm des 2008,
14, 953.
[8] J. M. Forbes, M. E. Cooper, Amino Acids 2012, 42, 1185.
[9] M. Lassila, K. K. Seah, T. J. Allen, V. Thallas, M. C. Thomas,
R. Candido, W. C. Burns, J. M. Forbes, A. C. Calkin,
M. E. Cooper, J Am Soc Nephrol 2004, 15, 2125.
[10] Y. Sharma, S. Saxena, A. Mishra, A. Saxena, S. M. Natu, J Ocul
Biol Dis infor 2012, 5, 63.
[11] M. Chen, T. Curtis, A. Stitt, Curr Med Chem 2013, 20, 3234.
[12] M. Peppa, S. A. Raptis, Curr Diabetes Rev 2008, 4, 92.
[13] Z. Hegab, S. Gibbons, L. Neyses, M. A. Mamas, World J cardiol
2012, 4, 90.
[14] N. Pantidos, A. Boath, V. Lund, S. Conner, G. McDougall, J. J
Funct Foods 2014, 10, 201.
[15] B. W. Zhang, Y. Xing, C. Wen, X. X. Yu, W. L. Sun, Z. L. Xiu,
Y. S. Dong, Bioorg Med Chem lett 2017, 27, 5065.
[16] K. Han, Y. Li, Y. Zhang, Y. Teng, Y. Ma, M. Wang, R. Wang,
W. Xu, Q. Yao, Y. Zhang, Bioorg Med Chem lett 2015, 25, 1471.
[17] D. Semaan, J. Igoli, L. Young, E. Marrero, A. Gray, E. Rowan,
J Ethnopharmacol 2017, 203, 39.
[18] L. Han, C. Fang, R. Zhu, Q. Peng, D. Li, M. Wang, Int J Biol
Macromol 2017, 95, 520.
[19] J. Yan, G. Zhang, J. Pan, Y. Wang, Int J Biol Macromol 2014,
64, 213.
[20] L. Zeng, G. Zhang, Y. Liao, D. Gong, Food Funct 2016, 7, 3953.
[21] M. R. Bhosle, J. R. Mali, S. Pal, A. K. Srivastava, R. A. Mane,
Bioorg Med Chem lett 2014, 24, 2651.
[22] P. Kumar, M. Duhan, K. Kadyan, J. Sindhu, S. Kumar,
H. Sharma, Med Chem Comm 2017, 8, 1468.
[23] J. Dwivedi, K. Devi, Y. Asmat, S. Jain, S. Sharma, J Saudi
Chem Soc 2016, 20, S16.
[24] J. Sindhu, H. Singh, J. Khurana, C. Sharma, K. Aneja, Chin
Chem Lett 2015, 26, 50.
[25] D. D. Subhedar, M. H. Shaikh, M. A. Arkile, A. Yeware,
D. Sarkar, B. B. Shingate, Bioorg Med Chem lett 2016, 26, 1704.
[26] Y. Ali, M. S. Alam, H. Hamid, A. Husain, A. Dhulap, S. Bano,
C. Kharbanda, Bioorg Med Chem lett 2017, 27, 1017.
[27] M. F. Ansari, D. Idrees, M. I. Hassan, K. Ahmad, F. Avecilla,
A. Azam, Eur J Med Chem 2018, 144, 544.
[28] K. Liaras, M. Fesatidou, A. Geronikaki, Molecules 2018,
23, 685.
[29] S. Jain, A. Kumar, D. Saini, Exp Parasitol 2018, 185, 107.
[30] P. Balaji, D. Ranganayakulu, G. S. Reddy, Asian J Pharm 2017,
3, 9.
[45] E. Runge, E. K. Gross, Phys Rev Lett 1984, 52, 997.
[46] P. Stephens, F. Devlin, C. Chabalowski, M. Frisch, J. J Phys
Chem A 1994, 98, 11623.
[47] D. M. Gil, M. D. Lestard, O. E. Hernández, J. Duque,
E. Reguera, Spectrochimn Acta A Mol Biomol Spectros 2015,
145, 553.
[48] R. Parthasarathi, V. Subramanian, D. R. Roy, P. Chattaraj, Bio-
org Med Chem 2004, 12, 5533.
[49] F. De Proft, P. Geerlings, Chem Rev 2001, 101, 1451.
[50] Chattaraj, P. K.; Roy, D. R. Chem Rev 2007, 107, 9, 46.
[51] J. L. Reed, J Phys Chem A 1997, 101, 7396.
[52] Pauling, L. The Nature of the Chemical Bond Cornell univer-
sity press Ithaca, NY, 1960.
[53] R. G. Parr, W. Yang, J Am Chem Soc 1984, 106, 4049.
[54] T. Koopmans, Physica A 1933, 1, 104.
[55] L. Ferreira, R. D. Santos, G. Oliva, A. Andricopulo, Molecules
2015, 20, 13384.
[56] S. J. Y. Macalino, V. Gosu, S. Hong, S. Choi, Arch Pharm Res
2015, 38, 1686.
[57] B. Svensson, Plant Mol Biol 1994, 25, 141.
[58] R. Laskowski, M. MacArthur, D. Moss, J. Thornton, J Appl
Crystallogr 1993, 24, 946.
[59] S. B. Ferreira, A. C. Sodero, M. F. Cardoso, E. S. Lima,
C. R. Kaiser, F. P. Silva, V. F. Ferreira, J Med Chem 2010, 53,
2364.
[60] Morris, G.; Goodshell, D.; Huey, R.; Hart, W.; Halliday, R.;
Belew, R.; Olson, A. Autodock (version 3.05), Molecular
Graphics Laboratory, Department of Molecular Biology The
Scripps Research Institutes, in, La Jolla, CA, USA, 1999.
[61] Visualizer, D. S. version 2016 17.2.0.16349. Accelrys Software
Inc, in.
[31] M. F. Shehry, M. M. Ghorab, S. Y. Abbas, E. A. Fayed,
S. A. Shedid, Y. A. Ammar, Eur J Med Chem 2018, 143, 1463.

KUMAR ET AL.
15
[62] N. Rani, S. K. Sharma, N. Vasudeva, Evid Based Complement
Alternat Med 2012, 2012, 1. https://doi.org/10.1155/2012/
715912.
[63] F. M. Afrapoli, B. Asghari, S. Saeidnia, Y. Ajani, M. Mirjani,
M. Malmir, R. D. Bazaz, A. Hadjiakhoondi, P. Salehi,
M. Hamburger, DARU J Pharm Sci 2012, 20, 37.
[64] M. Frisch, G. Trucks, H. Schlegel, G. Scuseria, M. Robb,
J. Cheeseman, GAUSSIAN09. Revision E, Vol. 01, Gaussian
Inc., Wallingford, CT, USA 2009.
Rempfer, C.; Bordoli, L. Nucleic Acids Res 2018, 46(W1), W296.
https://doi.org/10.1093/nar/gky427
[73] DeLano, W. The PyMOL Molecular Graphics System, Version
1.1. Schrödinger LLC. 2002. Google Scholar 2014.
[74] R. A. Laskowski, J. A. C. Rullmann, M. W. MacArthur,
R. Kaptein, J. M. Thornton, J Biomol NMR 1996, 8, 477.
SUPPORTING INFORMATION
Additional supporting information may be found online
in the Supporting Information section at the end of this
article.
[65] A. D. Becke, J Chem phys 1992, 96, 2155.
[66] C. Lee, W. Yang, R. G. Parr, Phys Rev B Condens Matter 1988,
37, 785.
[67] D. Avci, Spectrochim Acta A 2011, 82, 37.
[68] E. F. Pettersen, T. D. Goddard, C. C. Huang, G. S. Couch,
D. M. Greenblatt, E. C. Meng, T. E. Ferrin, J Comput Chem
2004, 25, 1605.
[69] Dunbrack, R. L. Curr Opin Struc Biol 2002, 12, 431, Rotamer
Libraries in the 21st Century, 440.
[70] J. Wang, W. Wang, P. A. Kollman, D. Case, A. J Mol Graph
model 2006, 25, 247.
[71] O. Trott, A. Olson, J. J Comput Chem 2010, 31, 455.
[72] Waterhouse, A.; Bertoni, M.; Bienert, S.; Studer, G.;
Tauriello, G.; Gumienny, R.; Heer, F. T.; Beer, T. A. P.;
How to cite this article: Kumar P, Duhan M,
Sindhu J, Kadyan K, Saini S, Panihar N.
Thiazolidine-4-one clubbed pyrazoles hybrids:
Potent α-amylase and α-glucosidase inhibitors with
NLO properties. J Heterocycl Chem. 2019;1–15.
https://doi.org/10.1002/jhet.3882