Silica catalyzed one pot synthesis of hybrid thiazolidin-4-one derivatives as anti-tubercular and anti-inflammatory agent by attenuating COX-2 pathway

Article abstract of DOI:10.1080/00397911.2019.1643485

A novel series of a hybrid class of hybrid thiazolidin-4-one derivatives were designed and synthesized through one-pot catalytic synthesis. The reaction was catalyzed in the presence of silica-H₂SO4⁽⁺⁶⁾. The derivatives computational

Full text of DOI:10.1080/00397911.2019.1643485

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: 0039-7911 (Print) 1532-2432 (Online) Journal homepage: https://www.tandfonline.com/loi/lsyc20
Silica catalyzed one pot synthesis of hybrid
thiazolidin-4-one derivatives as anti-tubercular
and anti-inflammatory agent by attenuating COX-2
pathway
Prateek Pathak, Parjanya Kumar Shukla, Vladislav Naumovich, Maria
Grishina, Vladimir Potemkin & Amita Verma
To cite this article: Prateek Pathak, Parjanya Kumar Shukla, Vladislav Naumovich, Maria Grishina,
Vladimir Potemkin & Amita Verma (2019): Silica catalyzed one pot synthesis of hybrid thiazolidin-4-
one derivatives as anti-tubercular and anti-inflammatory agent by attenuating COX-2 pathway,
Synthetic Communications
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https://doi.org/10.1080/00397911.2019.1643485
Silica catalyzed one pot synthesis of hybrid thiazolidin-4-
one derivatives as anti-tubercular and anti-inflammatory
agent by attenuating COX-2 pathway
Prateek Pathaka , Parjanya Kumar Shuklab,c , Vladislav Naumovicha,
Maria Grishinaa , Vladimir Potemkina , and Amita Vermab
aLaboratory of Modeling of Drugs, Higher Medical and Biological School, South Ural State University,
b
Chelyabinsk, Russia; Bioorganic and Medicinal Chemistry Research Laboratory, Department of
Pharmaceutical Sciences, Faculty of Health Sciences, Sam Higginbottom University of Agriculture,
c
Technology and Sciences, Allahabad, India; Krishnarpit Institute of Pharmacy, Uttar Pradesh Technical
University, Allahabad, India
ABSTRACT
ARTICLE HISTORY
Received 25 April 2019
A novel series of a hybrid class of hybrid thiazolidin-4-one derivatives
were designed and synthesized through one-pot catalytic synthesis. The
reaction was catalyzed in the presence of silica-H2SO4(þ6). The deriva-
tives computational ADMET profile was calculated. The study shows
that most active derivatives have optimal logP, higher anti-inflammatory
activity score, and poor metabolism at the sight of P450-3A4 and 2D6.
The entire series of derivatives were further evaluated for anti-tubercular
(against Mycobacterium tuberculosis H37Rv (Resistant strain)) and anti-
inflammatory activity (in-vivo assay using Wistar rat). The result showed
that derivatives 4c, 4h, and 4m have significant potency against tested
M. tuberculosis. However, derivatives 4i and 4j found significantly active
against inflammation. In vitro COX inhibition assay also supported the
result in favor of selectivity and efficacy of derivatives.
KEYWORDS
ADME; anti-inflammatory
activity; docking;
thiadiazole; thiazolidine-
4-one
GRAPHICAL ABSTRACT
CONTACT Prateek Pathak
of Modeling of Drugs, Higher Medical and Biological School, South Ural State University, Tchaikovsky str. 20-A,
Chelyabinsk 454008, Russia; Amita Verma amitaverma.dr@gmail.com Bioorganic and Medicinal Chemistry
prateekpharm05@gmail.com; Vladimir Potemkin
potemkinva@susu.ru
Laboratory
Research Laboratory, Department of Pharmaceutical Sciences, Faculty of Health Sciences, Sam Higginbottom University
of Agriculture, Technology and Sciences, Allahabad 211007, India
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lsyc.
Supplemental data for this article is available online at on the publisher’s website.
ß 2019 Taylor & Francis Group, LLC

2
P. PATHAK ET AL.
Introduction
The competent novel medicinal agent with therapeutic efficiency is always a major con-
cern for the pharmacological chemist. Concomitantly, the development of tolerance
potential or resistance against any analogs after some time can seriously compromise its
clinical utility. This holds factual and creates key negative aspect for the medicinal
agents used in the treatment of persistent diseases.[1]
Tuberculosis (TB) is an ancient recognized communicable infection. It is a continual
necrotizing microorganism (Mycobacterium tuberculosis) incorporated infection with a
wide variety of manifestations.[2] The current data estimated that approximately one-
third of the world’s population is infected directly or indirectly with M. tuberculosis. In
this era, the global mortality rate due to TB stands in the top five positions. WHO fact
sheet states that around 2 million people are killed every year and estimated that till the
year 2020, nearly 1 billion people will be newly infected due to the lack of strengthened
control.[3,4] The great challenge faced during the treatment is the development of mono-
drug and multidrug-resistant strains of M. tuberculosis.[5] Thus, there is a requirement
of new skeletons with a novel mechanistic approach other than isoniazid (INH), rifam-
picin (RIF), and pyridazinamide (PZA). The last potential anti-tubercular agent rifam-
pin was introduced in 1960. Therefore, there is an urgent need for the development of
innovative anti-TB agents.[6]
Inflammation is the instantaneous reaction of the tissues and cells against damage
caused by pathogens or noxious stimuli such as chemicals or physical injury. Acute
inflammation is a short-term response that initiates the process of healing, namely, leu-
kocytes infiltrate the damaged region, removing the stimulus and repairing the tissue.
Chronic inflammation (persistent inflammation) is considered a contrast process which
results due to prolonged deregulated and maladaptive response. Chronic inflammation
activity participated in tissue destruction and failure of the tissue repair mechanism.[7]
This prolonged inflammation conditions allied with a persistent health condition such
as TB,[8] allergy, atherosclerosis, cancer, arthritis, cardiovascular diseases, cancer, dia-
betes, Alzheimer’s disease, pulmonary disease, and other autoimmune diseases.[7]
Pathophysiological correlation with TB and inflammation is displayed in Figure 1.[8]
The treatment of inflammation is overcome by the class of drugs named as non-ster-
oidal anti-inflammatory drugs (NSAIDs). These are the medicinal active class of com-
pounds, such as aspirin,[9] ibuprofen,[10] naproxen,[11] diclofenac,[12] and
indomethacin,[13] also utilized as analgesic and antipyretic. The main site of activity for
majorly NSAIDs is COX-1, COX-2 attenuated by PGs and thromboxane. The mechan-
ism of inflammatory response is illustrated in Figure 2. Evidence explained that the site
of COX-2 inhibition is the prime target for anti-inflammatory, analgesic, and antipyretic
behavior.[14] However, COX-1 inhibition leads to an undesirable side effect like gastro-
intestinal bleeding,[12] kidney problems,[13] and central nervous system effects.[14]
Studies explained that NSAIDs associated treatment may increase the risk of
stroke.[15,16] So, there is a need to concurring development of new NSAIDs toward min-
imal adverse effect with higher efficacy.
1,3,4-Thiadiazoles are an imperative category of heterocyclic compounds that reveal a
range of pharmacological efficacy such as anti-cancer,[17,18] antiviral,[19,20] antibacter-
ial,[21,22,23] antioxidant,[24] anxiolytic,[25] anti-tubercular,[26] anticonvulsant,[27] and

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Figure 1. Shows the multiple layers of regulation of inflammation in TB. Central panel: interactions of
M. tuberculosis (Mtb) with professional phagocytes results in activation of several pathways, which
concur to induce inflammation. IL-1 necessitates differential requirement for caspase-1 and subse-
quently inflammasome activation in infected myeloid cells. Inflammasomes, particularly NLRP3, are
indispensable for bioactive IL-1b release, and these platforms are regulated by interferons (IFN) via
negative (iNOS/NO and IL-10) and positive loops (GBP5). IL-1 affects TNF-a synthesis and TNFR expres-
sion, while Mtb impacts directly or via distinct eicosanoids on TNF-a abundance (LTB4 boosts and
LXA4 dampens TNF-a release). MiRNAs perturb TNF-a as well as IFN-g post-transcriptionally and per-
haps affect other mediators (IL-1, chemokines). Eicosanoids (PGE2 and LXA) and IFN (type I and II)
crosstalk with family members and probably additional networks exist between these molecules and
the above-mentioned mediators. Left panel: distinct proteinaceous and lipid mediators impact on the
fate of the infected cell. Eicosanoids direct cell death (apoptosis vs. necrosis), while abundant TNF-a
favors necroptosis and hyper-inflammation. Right panel: genesis of nascent granulomas is controlled
by immune and nonimmune cells via chemokines and cytokines. Local abundance of proteases (ser-
pins, cathepsins) and cytokines regulate transition of solid granulomas to necrotic ones. In addition,
matrix-metalloproteases, of myeloid or epithelial origin, modulate the extent of tissue damage. Hypo-
or hyper-reactions alter inflammation and, along with Mtb persistence, transform a physiological pro-
cess into a life-threatening condition. GBP5: guanylate binding protein 5; iNOS: inducible nitric oxide
synthase; IFN-g: interferon gamma; IL-1: interleukin 1; IL-10: interleukin 10; LTB4: leukotriene B4;
LXA4: lipoxin A4; miRNAs: microRNAs; PGE2: prostaglandin E2; TNF-a: tumor necrosis factor alpha.[8]
anti-inflammatory activities.[28] Thiazolidine-2,4-dione also initiates peroxisome prolifer-
ator-activated receptors (PPARs). These PPARs, mainly known as anti-diabetic agents,
act against diabetes type 2[29] but it is found that sharing of thiazolidine-2,4-dione
structure with two rings varies the range of other biological activity including anti-
inflammatory[30,31] and anti-tubercular. In the detection and aim of new medicinal
agents, the design and development of hybrid derivatives through diverse pharmaco-
phore combinations in one framework may lead toward interesting biological profiles.
Incited on these observations, in the present research, we advocate the one-pot synthe-
sis, docking, ADME profiling, 3D-QSAR study, anti-tubercular, and anti-inflammatory
screening of 5-m-substituted phenyl-[1,3,4] thiadiazol-2-ylamine contain thiazolidin-
4-one hybrid derivatives.

4
P. PATHAK ET AL.
Figure 2. Displayed cascade of metabolism of arachidonic acid by COX pathways.
COOH
N
N
H
N
H2N
EtOH
NH2
NH2
S
+
S
H2SO4
R
(1a-1e)
R
R'
N
CHO
N
N
N
N
O
S
R''
S
R'
+
+
NH2
silica-
H2SO4
S
HS
COOH
R''
R
R
(3a-3b)
(4a-4r)
(2a-2c)
(1a-1e)
Figure 3. Showed the scheme for the synthesis of desired product.
Result and discussion
Chemistry
One-pot synthetic approach is a smart technique to access the higher molecular hetero-
cyclic derivatives through the speedy and cost-effective scheme. So, it is gaining atten-
tion. This is a synthetic strategy in which the reactants undergo a gradual chemical
reaction in the same reactor. The major improvement of this chemical approach
involves the production of a final compound without isolating intermediates.[32–35]
Hence, pot reaction function takes into account, target compounds were synthesized by
utilizing Silica-H2SO4 as a catalyst. As illustrated in Figure 3 (Step 1), the synthesis of

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Table 1. showed the screening of the reaction conditions for the synthesis of 2-subsituted Phenyl-3-
(5-p-subsituted-[1,3,4]thiadiazol-2-yl)-thiazolidin-4-one (1a–r).
Entry
Catalyst
Condition
Reaction time
Yield
1
2
3
4
5
7
8
9
No catalyst
H2SO4
HCl
H3PO4
NaOH
FeCl2
ZnCl2
Silica-H2SO4
Ethanol/Reflux
Ethanol/Reflux
Ethanol/Reflux
Methanol/Reflux
Ethanol/Reflux
Ethanol/Reflux
Ethanol/Reflux
Ethanol/Reflux
27 h
09 h
45%
38%
12 h
Trace
13 h
6 h
5 h
34%
74%
82%
5-m-subsituted phenyl-[1,3,4]thiadiazol-2-ylamine derivatives 1a–e was consummated
by reacting ethanolic solution of different aromatic carboxylic acids with an aqueous
(þ6)
solution of thiosemicarbazide in the occurrence of concentrated H2SO4
at dynamic
state.[36] The next part of the study was aimed toward optimizing the reaction condition
during one-pot condensation.
In the first set of experiment, we tried several methods with catalyst, e.g. H2SO4,
HCl, H3PO4, ZnCl2, FeCl2, and without a catalyst. The results were shown in
Table 1. During reaction optimization, we found that 0.01 mol of activated silica-
H2SO4 could efficiently catalyze the reaction with maximum yield (82%) and time
duration. It was also found that the addition of other catalysts, e.g. H2SO4, HCl,
H3PO4, ZnCl2, FeCl2, either delayed the reaction time or failed the reaction. It is
also observed that without catalyst the reaction time extended up to 27 h with 45%
yield. However, the others could not catalyze the reaction in a competent way, e.g.
FeCl2 takes 13 h with 34% yield. While, in the absence of catalyst, the reaction did
not progress efficiently and took longer time. This confirms the function of the cata-
lyst for the conclusion of reaction. To reveal the role of solvent on the reaction and
product yield, the next component of the study was aimed to identify the suitable
solvent followed by hit and trial method. As a result of this, the reaction has been
carried out using diverse solvents system (illustrated in Table 1). It was advocated
that the highest yield and shorter reaction duration furnished in the presence of
ethanol. The observation showed that the reaction time has been twice longer in the
case of THF and dichloromethane. However, water found as ineffective as a solvent
system to carry this type of reaction. The catalyst (silica-H2SO4) and solvent (etha-
nol) optimization were followed and diverse targeted derivatives were synthesized.
The reaction scheme and their mechanism are shown in Figures 3 and 4, respect-
ively. However, their different substitutions are shown in Table 2.
The synthesis procedure was found easy and productive, and the products were separated
and purified by simple filtration and column chromatography. The structure of the deriva-
1
tives was confirmed by IR, H-NMR, 13C-NMR, and Mass spectroscopy. The FTIR results
were showed a stretch band between the ranges 3378 and 2912cmꢀ1, refer to the presence
of –NCS stretch for thiazolidine skeleton. The aromatic –C¼C stretching were specified
between 1569 and 1584cmꢀ1. The confirmation of C¼O functional group in the stretch was
measured between the range of 1609 and 1628cmꢀ1. However, N–N stretch was recorded
between the ranges of 1107 and 1176cmꢀ1. 1H-NMR data showed a doublet at d 3.17–3.94
range ascribed the presence of CH2 proton, triplet at d 4.01–6.24 range refers to CH proton

6
P. PATHAK ET AL.
R'
O
H
N
N
N
N
-O
N+
H H
NH2
R'
+
S
S
R
R'
R
R'
N
N
N
N
-H2O
H
HO
N
N
H
S
S
R
HO
Silica-H2SO4
R
SH
O
R'
R'
R''
N
N
N
N
H
H
-H2O
N
N
S
S
H
S
S
HO
R
R
O
R''
R''
O
Figure 4. Mechanism of the reaction involve in the synthesis.
Table 2. The different substitutions at various positions for the syn-
thesized compounds (4a–r).
Compound
R
R1
R11
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
H
NO2
OH
OCH3
Cl
H
NO2
OH
OCH3
Cl
H
NO2
OH
OCH3
Cl
NO2
OH
Ph-Br
Ph-Br
Ph-Br
Ph-Br
Ph-Br
Ph-Cl
Ph-Cl
Ph-Cl
Ph-Cl
Ph-Cl
Ph-F
Ph-F
Ph-F
Ph-F
Ph-F
Ph-Br
Ph-Br
Ph-Br
H
H
H
H
H
H
H
H
H
H
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
OCH3
of thiazolidine ring. Confirmation of Br–Ar, –CH exhibited a doublet at the range of d
6.61–7.50ppm. The 13C-NMR showed carbon signals between 17.90 and 174.80ppm that
explored the presence of thiazolidine-4-one as well as a thiadiazole ring. Eventually, the
structure of derivatives was found with the harmony of mass and elemental analysis.

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Table 3. The physiochemical properties (ADME) calculation of synthesized derivatives (4a–r).
Carrageenan
induced anti-
inflammatory
Metabolism at
CYP450: 3A4
Metabolism at
CYP450: 2D6
Maximum
metabolism score
activity (simulated
calculation)
Derivatives
LogP
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
3.16
2.74
2.94
3.32
3.39
3.15
2.74
2.93
3.32
3.39
3.11
2.72
2.91
3.28
3.34
2.89
3.10
3.47
3.28
0.97
0.97
0.83
0.53
0.91
0.88
0.99
0.94
0.28
0.00
0.96
0.38
0.86
0.59
0.97
0.97
0.96
0.57
0.90
0.74
0.94
0.97
0.99
0.97
0.59
0.60
0.68
0.03
0.005
0.89
0.60
0.88
0.95
0.32
0.0001
0.27
0.94
0.11
0.97
0.97
0.97
0.99
0.97
0.88
0.99
0.94
0.28
0.005
0.96
0.6
0.88
0.95
0.97
0.97
0.96
0.94
–
0.0024
0.9997
0.9994
1.0
1.0
1.0
1.0
1.0
0.99
0.00
0.9934
0.6972
0.9998
0.9980
0.9942
0.0919
0.0057
0.999
0.19
4l
4m
4n
4o
4p
4q
4r
Diclofenac
LogP is the logarithm of the octanol-water partition coefficient; 3A4 is the probability of metabolism at CYP450: 3A4;
2D6 is the probability of metabolism at CYP450: 2D6. Maximum metabolism score calculated by (max(“3a4_pred”,
“2D6_pred”)) Carrageenan induced anti-inflammatory activity (simulated calculation).
3D QSAR and ADME study
3D QSAR has a great relation with ADME profile of drug candidate. So, it is considered
as a noteworthy application for designing of a novel drug candidate. In this part of the
study, we evaluated the synthesized analogous for their QSAR and ADME profile. The
result expressed that all of the derived compounds explored optimal logP value (less
than 5) and followed Lipinski’s rule.[37] All the physicochemical characteristics data
showed in Table 3. However, the pharmacophore, antipharmacophore, and ballast com-
ponents of the derivatives 4i and 4j are illustrated in Figure 5. The whole series of the
derivatives explored that phenyl ring attached with thiazolidine ring renders great con-
tribution toward pharmacophoric potential. However, the ketone group within the thia-
zolidine ring showed response toward antipharmacophore character. The heteroatom
(N1) of the thiazole ring surprisingly showed antipharmacophore property. The refer-
ence drug diclofenac skeleton pharmacophore, antipharmacophore, and ballast parts are
illustrated in Figure 6. The confirmatory observation showed that oxygen atom of the
carboxylic acid plays a role as antipharmacophore. The comparative study emphasis
that hydrogen atom have potential against inflammation and may be selective subject to
further designing the molecule. The study showed that the derivatives 4c, 4d, 4f, 4i, 4j,
4l, 4n, and 4r have significantly lower metabolism toward CYP450: 3A4 than standard
drug diclofenac. However, the derivatives 4i, 4j, 4o, 4q, and diclofenac showed compar-
able metabolism on the site of CYP450 :2D6. The metabolism results are illustrated in
Table 3. The metabolism study also revealed that derivatives (4f, 4i, 4j, and 4l) may be
rendered the best anti-tubercular and anti-inflammatory activity due to increase the
possibility of attachment with selected protein. Therefore, taking into account ADMET
properties, the derivatives 4i and 4j were identified as the most promising molecules

8
P. PATHAK ET AL.
Figure 5. Pharmacophore (red), antipharmacophore (blue) and ballast (white) parts of the 4i and 4j
molecule against inflammation (L to R).
Figure 6. Pharmacophore (red), antipharmacophore (blue) and ballast (white) parts of the diclofinac
against inflammation (L to R).
due to their low probability of metabolism and optimal logP. As a direction of struc-
tural change for better activity profile, it is suggested that oxygen atom with the ring or
as a functional group should be replaced with any hydroxyl moiety. These minor
changes can improve the physicochemical characters as well as pharmacophore through
minimization of the antipharmacophore space of the derivatives.
Biological evaluation
Anti-tubercular activity
The targeted derivatives were subjected to in vitro anti-tubercular activity using the
broth dilution method. The activity of the derivatives was measured in term of min-
imum inhibitory concentration (MIC). The result shows that the whole series find mild
to significantly active against selected strain H37Rv. The result showed that among the

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Table 4. The MIC of synthesized derivatives (4a–r) against M. tuberculosis H37Rv (resistant strain).
Derivatives
MIC (mg/mL) (1)
MIC (mmol/L) (2)
pMICa (3)
ꢁꢁꢁ
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
12.5 0.01
25 0.01
0.2988071 0.01
0.53957222 0.01
0.014369137 0.01
0.0557587652 0.01
0.05521445 0.01
0.1104289 0.01
0.0298441482 0.01
0.01603057 0.01
0.2475799 0.01
0.122452978 0.01
0.034971882 0.01
0.120062432 0.01
0.008065 0.01
4.90
4.60
5.20
4.60
4.60
4.30
4.90
5.20
4
4.30
4.9030
4.301
5.50
4.30
4.60
4.602
4.30
4.90
ꢁꢁꢁ
6.25 0.01#
ꢁꢁꢁ
25 0.01
25 0.01
50 0.01
12.5 0.01
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
6.25 0.01#
ꢁꢁꢁ
100 0.01
50 0.01
12.5 0.01
50 0.01
3.125 0.01
50 0.01
25 0.01
25 0.01
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
0.124539 0.01
ꢁꢁꢁ
0.061591525 0.01
0.05237247 0.01
0.11151753 0.01
0.027034041 0.01
ꢁꢁꢁ
ꢁꢁꢁ
4q
4r
50 0.01
12.5 0.01
ꢁꢁꢁ
Control DMSO
Streptomycin
6.25
0.0214933 0.01
5.20
MIC lM (column 1) and mmol/lit (column 2) showed the minimum inhibitory concentration of tested derivatives against
broth dilution assay. LogPMIC (column 3) shows the pMICa inhibitory concentration calculated by stastica tool.
#
ꢁꢁꢁ
p < 0.001, p > 0.05 in comparison with standard (Dunnet’s t-test).
series derivative 4m, framed through phenyl substituent on the thiadiazole and floro-
phenyl on thiazolidine ring, renders significant activity (i.e. MIC 3.12 mg/mL), whereas
the addition of bromo-phenyl ring through the removal of floro-phenyl on thiazolidine
ring (derivative 4c) slightly lowers the activity (MIC 6.25 mg/mL). Derivative 4h was
constructed, namely, minor changes in the ring, i.e. removal of a methyl group from
thiazolidine ring and addition of chloro-anilino ring through the substitution of a
bromo-Phenyl ring of derivative 4c found similar active. The results state that the
derivative 4m has a significant, derivative 4c, 4h have similar, and rest of the series
have mild to moderate potential against the reference drug. The activity data are shown
in Table 4, and the graphical presentation is expressed in Figure 7. The assay revealed
that chloro or bromo substitution on phenyl ring and methyl substitution at thiazoli-
dine-4-one skeleton render the anti-tubercular efficacy.
In vitro cyclooxegenase (COX) inhibition assay
The synthesized target substituted phenyl-3-(5-p-subsituted-[1,3,4]thiadiazol-2-yl)-thiazoli-
din-4-one derivatives (4a–r) was evaluated in vitro for cyclooxygenase (COX) enzyme inhib-
ition at 10 lM concentration. The results were reported in percent of inhibition and
selectivity index. The activity measurements were obtained through the comparison against
reference drug Celecoxib. The enzymes inhibition result illustrated in Table 5. The result
showed that the entire set of target derivatives has excellent inhibitory activity. The deriva-
tives 4i and 4j revealed the prominent inhibitor within the series with 55 and 50% inhibition
against COX-1 and 80 and 75.42% against COX-2 enzyme, respectively. Furthermore, a
slight decline in the inhibition activity observed in 4d, 4e, and 4f (48% against COX-1 and
60.12% against COX-2). Apart from this, a significant drop in activity inhibition observed

10
P. PATHAK ET AL.
Anti-tubercular activity
150
100
50
0
4i
4l
4f
4j
4k
4c
4e
4r
4a
4g
4o
4n 4p 4q
4b
4d
4h
4m
Derivatives
Standard agent
Figure 7. Shows the anti-tubercular activity of the derivatives and standard drug.
Table 5. In vitro cyclooxegenase (COX) inhibition assay of synthesized compounds (4a–r).
Derivatives
COX-1(10 mL, i.e. 1.0 mM)
COX-2(10 mL, i.e. 1.0 mM)
Sib (COX-2/COX-1)
ꢁꢁꢁ
ꢁꢁꢁ
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
0.30 0.01
0.30 0.01
52.12 0.04
52.20 0.25
48.50 0.11
60.12 0.08
60.12 0.50
60.12 0.28
54.10 0.75
173.7
174
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
0.20 0.01
242.50
125.25
125.25
125.25
112.70
135
0.48 0.01#
0.48 0.01#
0.48 0.01#
0.48 0.01#
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
0.40 0.01
0.55 0.01
54.00 50
80.00 1.00#
145
ꢁꢁꢁ
0.50 0.01#
75.42 1.00
42.62 0.23
55.25 0.05
38.10 0.15
45.10 0.02
47.25 0.05
45.85 0.15
45.62 0.18
45.11 0.11
80.00 1.00
150.84
142.06
115.10
190.5
128.85
135
114.62
114.05
112.77
160
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
0.30 0.01
4l
0.48 0.01#
ꢁꢁꢁ
4m
4n
4o
4p
4q
4r
0.20 0.01
0.35 0.01
0.35 0.01
0.40 0.01
0.40 0.01
0.40 0.01
0.50 0.01
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
Celecoxib
% inhibition showed the means of two determinations using an ovine COX-1/COX-2 assay kit. Selectivity index (COX-2/
COX-1).
by the derivatives 4a–c, 4g, 4h, and 4k–r. The result showed that the derivative 4m has low-
est inhibition potency in the series. The graphical presentation of the enzyme inhibition
against COX-1 and COX-2 is displayed in Figure 8a and b. However, the selective index
against specific enzyme displayed in Figure 9a and b.
In vivo anti-inflammatory activity
We examined the in-vivo anti-inflammatory activity of synthesized compounds (4a–r),
which showed the specificity for COX-2 enzyme during in vitro assay. The percentage
protection against carrageenan-induced inflammation shown by derivatives (4a–r) by

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SYNTHETIC COMMUNICATIONSV
11
(a)
COX-1 Inhibition
0.6
0.4
0.2
0.0
f
c
d
k
4j
4
n
4i
4l
4
4
4e
4r
4p 4q
4a
4g
4o
4b
4
4h
4
4m
Derivatives
Standard agent
(b)
100
80
60
40
20
0
COX-2 Inhibition
i
j
k
q
4
4l
4f
4
4
4c
4e
4r
4a
4g
4o
4b
4d
4h
4n
4p 4
4m
Derivatives
Standard agent
Figure 8. Shows in vitro COX-1/COX-2 (a, b) enzyme inhibition assay of the compounds.
comparing with standard (diclofenac) at regular interval of time, i.e. 0, 1, 3, and 6 h.
The anti-inflammatory activities of synthesized compounds in term of mean difference
in Paw volume inhibition are given in Table 6, whereas the percentage inhibition of
paw edema is illustrated in Table 7 and Figure 10. The result explored that the entire
series 4a–r exhibited the anti-inflammatory activity in the range of 10.00–60.00% inhib-
ition at 1 h, 26.32–63.1% inhibition at 3 h, and 32.14–64.29% inhibition at 6 h.
The series of the derivatives 4a–e were framed through the substitution of Br-phe-
nyl ring at C-8 position thiazolidine skeleton. However, at the C-2 position of the
thiadiazole ring was renders different substitutions. The derivative 4a construct,
namely, the addition of phenyl ring to the thiadiazole renders mild to moderate
edema inhibition, i.e. 30% at 1 h, 36.84% at 3 h, and 35.71% at 6 h. Introduction of
the nitro group in phenyl ring which is attached at thiadiazole lowers the anti-
inflammatory response in the delayed time interval (30% at 1 h, 31.58% at 3 h, and
35.71% at 6 h). The derivative 4c obtained by the substitution of phenol ring in the
place of nitrobenzene tends the minimal inhibition. The results showed that
phenol ring a has negative impact on anti-inflammatory activity. Addition of

12
P. PATHAK ET AL.
300
Selective index
200
100
0
i
j
4
4
r
g
k
q
4
4
4l
4m
4f
nt
ge
4c
4e
4a
4
4o
4n 4p 4
4b
4d
4h
a
d
r
Derivatives
nda
a
t
S
Selectivity index
4a
Ref
4r
4b
4q
4p
4c
4o
4n
4d
4e
4m
4f
4l
4g
4k
4h
4j
4i
Figure 9. Shows selective index COX-1/COX-2 (a, b) enzyme inhibition assay of the compounds.
Table 6. Anti-inflammatory activity of synthesized compounds (4a–r) on carrageenan-induced acute
paws edema.
Mean difference in Paw volume (mL) after drug treatment (Mean SEM)
Compound code
0 min
1 h
3 h
6 h
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁ
ꢁꢁ
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
0.29 0.01
0.28 0.01
0.26 0.01
0.30 0.01
0.31 0.01
0.29 0.01
0.33 0.01
0.30 0.01
0.28 0.01
0.30 0.01
0.36 0.01
0.35 0.01
0.34 0.01
0.36 0.01
0.37 0.02
0.35 0.02
0.39 0.01
0.37 0.01
0.32 0.01
0.35 0.01
0.44 0.01
0.40 0.01
0.43 0.01
0.35 0.01
0.41 0.01
0.37 0.01
0.42 0.01
0.38 0.01
0.48 0.01
0.32 0.01
0.41 0.01
0.41 0.01
0.40 0.01
0.43 0.01
0.43 0.02
0.40 0.02
0.44 0.01
0.43 0.01
0.35 0.02
0.39 0.01
0.50 0.02
0.46 0.02
0.47 0.02
0.41 0.02
0.46 0.01
0.43 0.01
0.46 0.01
0.43 0.02
0.57 0.02
0.35 0.01
0.47 0.01
0.46 0.01
0.45 0.01
0.48 0.01
0.49 0.02
0.46 0.02
0.48 0.01
0.47 0.01
0.38 0.02
0.42 0.01
0.54 0.02
0.50 0.02
0.51 0.02
0.47 0.02
0.51 0.01
0.48 0.01
0.52 0.01
0.48 0.02
0.66 0.02
0.38 0.01
0.37 0.01#
ꢁ
0.34 0.01
0.34 0.01
0.28 0.01
0.33 0.01
0.29 0.02
0.35 0.02
0.31 0.01
0.38 0.01
0.27 0.02
ꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁꢁꢁ
ꢁ
4q
4r
ꢁꢁꢁ
Control
Standard drug (Diclofenac)
ꢁꢁꢁ
ꢁꢁꢁ
ꢁ
Note: The data were analyzed by oneway ANOVA followed by Dunnett’s t-test using n ¼ 6 animals in each group;
#
ꢁ
ꢁꢁ
p < 0.05, p < 0.01,
ꢁꢁꢁ
p < 0.001 (s), p > 0.05 (ns) in comparison with control (Dunnet’s t-test).

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Table 7. The percentage inhibition of paw edema of synthesized compounds (4a–r) in carrageenan-
induced paws edema model.
Percentage inhibition of paw edema
Log % inhibition at 1 h
Drug code
1 h
3 h
6 h
4.52
Standard drug (Diclofenac)
50
30
30
20
40
40
40
40
30
60
50
30
40
10
30
20
20
30
30
57.89
36.84
31.58
26.32
31.58
36.84
42.11
42.11
31.58
63.16
52.63
31.58
36.84
31.58
31.58
31.58
26.32
42.11
36.84
60.71
35.71
35.71
32.14
35.71
35.71
39.29
46.43
39.29
64.29
57.14
39.29
42.86
39.29
32.14
35.71
32.14
39.29
39.29
4.52
4.69
4.39
4.39
4.39
4.39
4.52
4.22
4.30
4.52
4.397
5.00
4.52
4.69
4.69
4.52
4.52
4.30
4.52
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
4q
4r
methoxy-phenyl ring (derivative 4d) (40% at 1 h, 31.58% at 3 h, and 35.71% at 6 h)
and choloro-benzene (derivative 4e) (40% at 1 h, 36.84% at 3 h, and 35.71% at 6 h)
explored slight improvement in activity.
The series of the derivative 4f–j framed through the substitution of Cl-phenyl ring
at C-8 position of the thiazolidine skeleton and C-2 position of the thiadiazole ring
were render different substitutions. The derivative 4f consist of phenyl ring at thia-
diazole skeleton tends the slight improvement in anti-inflammatory response at late
phase (31.58% inhibition at 3 h and 35.71% at 6 h), whereas the initial inhibition
response at 1 h recorded same as derivative 4e. Nitro-phenyl group on thiadiazole
skeleton contains derivative 4g has similar anti-inflammatory response as derivative
4f. The derivative 4h having hydroxyl-Ph substitution at C-2 position of the thiadia-
zole ring showed mild inflammation inhibition. To our surprise, methoxy-benzene
ring at C-2 position of the thiadiazole ring (derivative 4i) showed potential inhib-
ition than standard drug celecoxib. The derivative explored 60% inhibition at 1 h,
63.16% inhibition at 3 h, and 64.29% inhibition at 6 h. The replacement of methoxy-
phenyl group with chloro-phenyl in derivative 4j slightly lowers the activity but still
shows significant activity as standard. The SAR of both derivatives 4i and 4j indi-
cates that the introduction of methoxy-Ph and Cl-Ph group on C-2 position of thia-
diazole along with Cl-Ph substitution at C-8 of thiazolidine ring surprisingly
improve the activity.
The derivatives 4k–o constructed, namely, the substitution of the floro-phenyl ring at
C-8 position of the thiazolidine skeleton while at the C-2 position of the thiadiazole
ring was renders the different substitutions. The derivatives 4k–o showed mild to mod-
erate activity. The series of derivatives 4p–r consist of bromo-Ph ring substitution at C-
8, methyl group at C-11 of thiazolidine, and paternal substitution at C-2 position of
thiadiazole ring. The standard drug showed 50.00% inhibition against inflammation at
interval of 1 h, 57.89% at 3 h, and 60.71% at 6 h. The series of derivatives (4k–o) showed

14
P. PATHAK ET AL.
80
Paw edema inhibition at 1h
60
40
20
0
t
e
a
4i
4l
m
4
4f
4j
4c
4
4r
ag
4
4g
4o
St
4b
4d
4h
4k
4n
4p 4q
en
d
r
Derivatives
da
an
80
60
40
20
0
Paw edema inhibition at 3h
t
4i
4l
4m
4f
4j
4k
n
e
4c
4e
4r
ag
4a
4g
4o
4n 4p 4q
4b
4d
4h
d
r
a
Derivatives
d
an
t
S
80
60
40
20
0
Paw edema inhibition at 6h
t
4i
4l
4m
4f
4j
4k
n
e
4c
4e
4r
ag
4a
4g
4o
St
4b
4d
4h
4n
4p 4q
d
r
nda
Derivatives
a
Figure 10. Shows the graphical bar of in vivo anti-inflammatory activity of the derivatives (% inhib-
ition of paw edema volume) at 1 h, 3 h, and 6 h against carrageenan-induced rat paw edema.
mild activity. The study revealed that the derivatives 4i and 4j are the most prominent
derivatives. On the basis of these results of the study, we can conclude that methoxy
phenyl and chlorophenyl substitutions are important for anti-inflammatory activity. The
SAR of the derivatives showed that attachment of an electron withdrawing group on the
ring make molecules more attractive toward activity.
Anti-inflammatory activity and metabolism prognosis
The cytochrome-P450 substrates are the influential key factor for drug metabolism. The
studies revealed that the better activity of any selective candidate can be improved by

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15
lowering the metabolism tendency at the cytochrome-P450 site. Here, we performed
statistical analysis to understand and predict the correlation between the drug biological
activity and metabolism at cytochrome-P450 subtype 3A4 and 2D6. The scattered plot
of the biological activity vs. metabolism displayed in Figure 11a–i. The results showed
that the derivatives 4i, 4j, 4l, 4d, 4r, and 4n showed better predicted metabolism score
(less than 60%, i.e. 0.28, 00, 0.38, 0.53, 0.57, and 0.59, respectively) against P450-3A4.
However, derivatives 4i, 4j, 4p, 4q, 4o, 4g, 4l, and 4f have tendency to prominently
resist against metabolism at P450-2D6 (score are 0.03, 0.005, 0.0001, 0.27, 0.32, 0.60,
0.60, and 0.59, respectively). The overall study showed that the derivatives 4i (con-
structed through the substitution of the methoxy-benzene ring at the C-2 position of
thiadiazole ring) and 4j (constructed via the substitution of the chlorophenyl ring at the
C-2 position of thiadiazole ring) have lower metabolism value. Whereas, the practical
evidence shows that both of the candidate 4i and 4j have a prominent anti-inflamma-
tory response. This study revealed that the metabolism at the site of 3A4 and 2D6 of
cytochrome-P450 in a considerable hurdle in the way of significant anti-inflamma-
tory response.
Docking study
Fascinated by the excellent anti-inflammatory activity shown by target molecules, where
COX-2 enzyme is overexpressed, the interaction with COX-2 receptor and its inhibition
makes confirmatory our results. The study is based on the genetic algorithm and in-sil-
ico methodology. The study utilized to understand the binding efficiency of derivatives
with the COX-2 receptor protein. The approach also validates the binding mode and
participating amino acid group with synthesized derivatives at the site of the active con-
formation of the co-crystal ligand S58701. In the docking calculations, LF rank score
showed the virtual screening score and used to identify correct ligand pose. The nega-
tive value of LF rank refers to suitable for the selection of pose docked in protein active
site. Whereas LFdG, i.e., DG score designed for the estimation of free energy of ligand-
protein complex in kcal/mol, LFV score refers to virtual screening docking score; this
shows the score for the virtual screening of active ligand to produce maximum effi-
ciency. LFLE refers to an estimated ligands efficiency computed from the lead finder G-
score. The result showed that each of the derivatives has an affinity toward COX-2
receptor. The derivatives 4b, 4c, 4d, 4e, 4i, 4j, 4n, 4o, and 4r showed H-bond
interaction and steric clashes. However, the rest of the series of derivatives only have a
tendency to interact through steric clashes with the receptor protein. We observed that
co-crystal ligand S58701 and derivatives 4d, 4e, 4j, 4n, 4o, 4q, and 4r have H-bond
interaction with identical amino acid residue GLN-192. The study also showed that the
ligand S5870, 4c, 4f, 4m, and 4k have the lowest binding energy (kcal/mol) and LFV
score. The conclusion based upon the H-bond interaction, lower DG docking score, and
better LFLE score; we figure out that derivatives 4i and 4j are an effective inhibitor of
COX-2. The details of ligand interaction with receptor residue and energy calculation
are illustrated in Table 8. The interaction mode between COX-2 domains and the syn-
thesized derivatives 4i and 4j is given in Figure 12.

16
P. PATHAK ET AL.
Figure 11. Shows the graph for the metabolism vs anti-inflammatory response of the derivatives
(4a–r). (a) Shows the scatterplot between COX-1 and metabolism at P450-3A4. (b) Showed the scat-
terplot between COX-1 and metabolism at P450-2D6. (c) Showed the scatterplot between COX-1 and
maximum metabolism score of the derivatives at P450 on the site of 3A4 and 2D6. (d) Showed the
scatterplot between COX-2 and metabolism at P450-3A4; (e) shows the scatterplot between COX-2
and metabolism at P450-2D6. (f) Showed the scatterplot between COX-2 and maximum metabolism
score of the derivatives at P450 on the site of 3A4 and 2D6. (g) Displayed the scatterplot between
selectivity index of COX-1/COX-2 and metabolism at P450-3A4. (h) Displayed the scatterplot between
selectivity index of COX-1/COX-2 and metabolism at P450-2D6. (i) Displayed the scatterplot between
selectivity index of COX-1/COX-2 and maximum metabolism score of the derivatives at P450 on the
site of 3A4 and 2D6.

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SYNTHETIC COMMUNICATIONSV
17
Figure 11. Continued.

18
P. PATHAK ET AL.
Figure 11. Continued.

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SYNTHETIC COMMUNICATIONSV
19

20
P. PATHAK ET AL.
Figure 12. Image of the synthesized derivatives (4i and 4j from up to down) into the active site of
COX-2 (PDB:1CX2) showed the interaction side chain of amino acid (color figure online), green color
dotted line showed the H-bond interaction with amino acid residue.
The most pharmacologically active derivative 4i showed H-bond interaction with AA
residue O24-ASP515 (2.2 Å) and steric clashes H53-HIS351 (4.0 Å). The derivative
showed LF rank score ¼ 7.531 kcal/mol, DG docking score ¼ 7.806 kcal/mol, LFV score
¼ 8.01 kcal/mol, and LFLE score ¼ 0.3. Results indicated that 4i and 4j intensively
showed interaction with COX-2 through H-bonds and hydrophobic interactions. The
derivatives 4b, 4c, 4d, 4e, 4i, 4j, 4n, 4o, and 4r had longer, broader structures when
compared with the co-crystal ligand and the protein binding pocket size. This was an
extensive cause for minor discrepancies in the binding energies while comparing with
experimental data. The binding mode between COX-2 domain target and the derivatives
4a–r including S58701, the structures in complex derived from the best dock results are
given in Figure 13. These multiple interactions with parent skeleton proved that

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SYNTHETIC COMMUNICATIONSV
21
Figure 13. Protein COX-2 (PDB: 1CX2) complex with 4a-4R (stick) compounds including the S58701
co-crystal ligand (stick and ball).
synthesized derivative have remarkable potency to fit with similar protein as the refer-
ence drug and can interact in similar pattern and fashion.
Conclusions
In the present research, we delivered a series of silica catalyzed one-pot synthesis of 5-
m-substituted phenyl-[1,3,4] thiadiazol-2-ylamine containing thiazolidin-4-one hybrid
derivatives. Furthermore, the physicochemical and 3D-QSAR analyses were performed.
The study revealed that a whole series of derivatives have optimal logP value, which
indicates that the compounds have a better tendency toward transportation through
physiological barriers. The metabolism study over CYP450: 3A4 and CYP450: 2D6
showed that synthesized derivatives 4f, 4i, 4j, and 4l have minimal affinity toward it.
In vitro anti-tubercular activity assay showed that derivatives 4c, 4h, and 4m have
potential inhibitory action against M. tuberculosis H37Rv (Resistant strain) but the
metabolism study revealed that the possibility of molecules to reach on site of action is
moderate during in-vivo anti-tubercular assay. In vitro cyclooxygenase (COX) inhibition
assay of synthesized compounds showed that derivatives are more selective toward
COX-2 inhibition. Furthermore, the anti-inflammatory activity assay also confirms that
the derivatives 4i and 4j have a prominent response against inflammation. The Docking
studies recommended that derivatives have a tendency to interact with receptor protein
similar to Cyclooxygenase-2 (Prostaglandin Synthase-2) – S5870 complex. So, our efforts
could be to a great extent positive toward the development of new potential analog tar-
geting COX-2 pathway.

22
P. PATHAK ET AL.
Experimental
Chemistry
The experiment was carried out using commercially available analytical grade solvents
and reagents without further purification. Melting points of the synthesized compounds
were determined in an open capillary tube Hicon Melting point apparatus and uncor-
rected. Thin layer chromatography (TLC) was performed on silica gel-G coated plates
to detect the completion of the reaction. The diverse mobile phase was selected in dif-
ferent proportions according to the assumed polarity of the products. The spots were
visualized by exposure to the Iodine vapor. Infrared (IR) spectra were recorded in
Perkin Elmer RX-I Spectrophotometer using KBr pellets and the reported wave num-
1
bers are given in cmꢀ1. H NMR spectra were recorded in DMSO-d6 on Cryo-magnet
Spectrometer 400 MHz (Bruker, Billerica, MA). However, 13C NMR was recorded in
CDCl3 using Bruker Avance II 100 NMR spectrometer. Chemical shifts were reported
as d (ppm) relative to TMS as internal standard. Mass spectra were recorded using
Waters Xevo G2-XS QTof masst spectrophotometer. Elemental analysis was carried out
on Vario EL-III CHNOS elemental analyzer.
General procedure
Substituted phenyl-[1,3,4]thiadiazol-2-ylamine (1a–1e)
An aromatic carboxylic acid (0.05 mol) and an aqueous solution of thiosemicarbazide
(0.05 mol) were added into ethanol with constant starring. Now few drops of concentric
sulfuric acid mixed and heated under reflux (80–90 ꢂC) for 4 h, till the completion of
the reaction as indicated by TLC. The reaction mixtures were cool and poured to ice-
cold water, basified with 10% Na2CO3 solution, filter, dried, and recrystallized from a
suitable solvent.
Multi-component one-pot synthesis of target substituted phenyl-3-(5-p-subsituted-
[1,3,4]thiadiazol-2-yl)-thiazolidin-4-one derivatives (4a–r)
A solution of an appropriate 2-amino-5-aryl-1,3,4-thiadiazole (1a–e) (0.01 mol), corre-
sponding benzaldehyde (2a–c) (0.01 mol), thioglycolic acid derivatives (3a–b) (0.01 mol)
in ethanol (15 mL) was heated under reflux in the presence of a catalytic amount of
activated silica-H2SO4 (0.01 mol), till the completion of reaction as indicated by TLC
(single point). The reaction mixture was washed systematically with water, filtered, and
purified using column chromatography to afford pure products.
Pharmacological evaluation
Anti-tubercular activity
Anti-tubercular evaluation of the derivatives performed the broth microdilution method
(BMM).[6,38] Clinical resistant and reference strain (M. tuberculosis: H37Rv) were
obtained from the Department of Microbiology, Banaras Hindu University, India. Fresh
colonies of LJ medium were transferred in 3–4 mL phosphate buffered saline with 6–9

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SYNTHETIC COMMUNICATIONSV
23
sterile glass beads containing a tube. Now tubes were vigorously agitated on a vortex
mixer and clumps were allowed to settle for 30 min, collect the supernatant into another
tube adjust pH with phosphate buffer saline to equal the density of 0.5 McFarland
standards for use as the standard inoculums in the BMM. In U-shaped 96-well micro-
titer plates were filled with 0.1 mL 7H9 broth, supplemented with oleic acid, albumin,
dextrose, and catalase. Two parallel broths were prepared for each with concentrations
ranging from 500 to 3.9 lg/mL and inoculated with 5 lL 0.5 McFarland standard bacter-
ial suspensions. A control also prepared for the study, and the microtiter plates were
sealed and incubated at 37 ꢂC for 14 days.
MIC calculation
Diffusion tests widely used to determine the susceptibility of organisms isolated from
clinical specimens have their limitations; when equivocal results are obtained or in pro-
longed serious infection, e.g. bacterial endocarditis, the quantization of antibiotic action
ꢀ
vis-a-vis, the pathogen needs to be more precise. Also, the terms “Susceptible” and
“Resistant” can have a realistic interpretation. Thus, when in doubt, the way to a precise
assessment is to determine the MIC of the antibiotic to the organisms concerned.
In vitro cyclooxegenase (COX) inhibition assay
Derivatives 4a–r were evaluated against COX-1 and human recombinant COX-2 by
using colorimetric enzyme assay kit (Catalog No. 760131, Cayman Chemicals Inc., Ann
Arbor, MI, USA).[39] The peroxidase activity is determined colorimetrically by checking
the appearance of oxidized N,N,N0,N0-tetramethyl-p-phenylenediamine (TMPD) at
590 nm. Stock solutions of test compounds (10 mL, i.e. 1 mg/mL) were prepared by dis-
solving in DMSO. All test compounds are mixed with the series of supplied reagents,
buffer solution (0.1 M Tris-HCl, pH 8), heme, and either COX-1 or COX-2 enzyme.
These solutions were incubated for a period of 5 min at 25 ꢂC, after which colorimetric
substrate TMPD and arachidonic acid was added quickly. the solution was shaken for a
few seconds and then incubated at 25 ꢂC for 2 min. The product of this reaction produ-
ces a blue color that absorbs at 590 nm. The intensity of blue color was determined by a
microplate reader (power wave XS2). A blank solution prepared, namely, the addition
of all the assay components, except the substrate. By removing the blank control value
you can obtain the corrected activity. Celecoxib (1 mM) was used as a standard drug.
The percent COX inhibition was calculated using following equation:
AI
COX inhibition activity % ¼ 1 ꢀ
ꢃ 100
(1)
C
where AI is the absorbance of the inhibitor at 590 nm and C is the absorbance of the
100% initial activity without inhibitor at 590 nm.
In-vivo anti-inflammatory activities determination
The synthesized derivatives were evaluated for anti-inflammatory activity. The carra-
geenan-induced acute paw edema model was applied for the assay as mentioned by

24
P. PATHAK ET AL.
Winter with minor modifications.[39 40]
The animals (Wistar rat ranging weight
,
150–200 g) were procured from Adina Institute of Pharmaceutical Sciences, Sagar, India.
The animals were weighed and divided into control, standard, and test groups (each
having six animals). Each group kept in the optimal condition, i.e. temperature
25–28 ꢂC, under 12 h light/dark cycle, and proper access to food. The first group (con-
trol) was treated with 1 mL of 0.5% sodium carboxymethyl cellulose (sodium CMC).
The second group was administered with a dose of 20 mg/kg of the suspension of diclo-
fenac (standard) and the test group (third) was treated with an equimolar dose of the
test suspension. After 30 min, the animals were injected with 0.1 mL of 1% carrageenan
in normal saline, subcutaneously to the subplantar region of the right hind paw. The
paw volume was measured at 1, 3, and 6 h, using plethysmometer. Paw edema volume
was compared with the vehicle control group and percent reduction was calculated as
% edema inhibition ¼ ðVt–VcÞcontrol–ðVt–VcÞtested=ðVt–VcÞcontrol ꢃ 100
(2)
where Vt is the volume of edema at specific time interval and Vc the volume of edema
at zero time interval.
The results are analyzed using the statistical significance (expressed as mean stan-
dard error of mean (SEM)) between the vehicle control and the treated groups using
one-way ANOVA followed by Dunnett’s test using Graph Pad Instant software. The
approval for the use of animal was obtained from the Institutional Ethics Committee of
Adina Institute of Pharmaceutical Sciences, Sagar (M.P), India (Reg. No. 1546/PO/E/S/
11/CPCSEA).
Acute toxicity
According to OECD-423 guidelines for acute toxicity study, Adult and healthy Wistar
rats of both sexes weighing 150–200 g were used in this experiment. Animals were div-
ided into groups of five each and they were starved for at least 24 h before the experi-
ment. The control group receives a 1% solution of sodium carboxy methyl cellulose.
Test group received the test compound solution in sodium carboxy methyl cellulose
(1%) in doses of 100–1000 mg/kg body weight and administered intraperitonially. The
animals were observed for 48 h from the time of administration of test compounds to
recording the mortality. The compounds used for toxicity studies are found safe as no
mortality is reported at the doses of 100–1000 mg/kg body weight.
Computational methodology
All the computational studies were carried out on a four CPUs (Intel Core2 Quad CPU
Q9550 @ 2.83 GHz) ACPI x64 workstation with windows 8.1 operating system. The
protein was prepared, docked and its interaction with different ligands was studied
using Cresset Discovery Services flare.[41]
Receptor preparation
The ZD6474 ligand-protein (protein id: 1CX2) complex was downloaded from the
Protein Data Bank (https://www.rcsb.org/) into Flare and prepared using the Build

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SYNTHETIC COMMUNICATIONSV
25
Model10 tool from BioMol Tech, 11 to add hydrogen atoms, optimize hydrogen bonds,
remove atomic clashes, and assign optimal protonation states to the protein structure.
Any shortened protein chain was covered as part of the protein preparation. Evaluation
of correct protonation state of ligands, amino acid side chains and re-optimize water
orientations of suboptimal water hydrogen bonding framework on the binding site was
confirmed visually. As many of the modeled binding modes clash with the flexible side
chain of amino acid residue, the side chain atoms were minimized with the XED force
field 12 for each ligand.
Ligand setup
The structures of compounds were prepared using Marvin Sketch 5.5.0.1 software.[42]
Hydrogen atoms were added in the structure. All the atom MMFF94s force field param-
eterization was assigned and then energy minimized through transformation obtained at
pH 7. Gasteiger partial charges were added to the ligands. Non-polar hydrogen atoms
were merged, and rotatable bonds were defined.
Docking
Docking, a major computational reproduction study used to predict the ligand binding
with receptor by site difference and the inflexibility of ligands, were optimized due to
the receptor. Ligand Fit protocol of Cresset flare was used and previously defined affin-
ity (grid) is used for the calculation.
Theoretical calculations
3D QSAR calculations[43 44]
Shoe”[45–47] method and within the CoMIn algorithm[46 48]
,
achieved, namely, construction of the “Cinderella
(cross validation quality is
,
greater than 0.98 during anti-inflammatory activity). The pharmacophore part (in red),
antipharmacophore skeleton (blue in color), and inactive part (white color) of the most
promising synthesized derivatives (4g, 4i, and 4j) are displayed in Figure 4. The white
part of the ring have not role in pharmacological response but accountable for structure
configuration and matrix function to provide the necessary mutual arrangement of
pharmacophoric fragments. The ADME computations, e.g. logP, toxicity, metabolism at
CYP450: 3A4, CYP450: 2D6, and predicted Carrageenan induced anti-inflammatory
activity was carried out using the website www.chemosophia.com.[49]
Statistical analysis
The data are expressed as mean SEM for each group. Statistical analysis was done
using GraphPad Prism version 5.0 software. An ANOVA followed by Dunnett’s t-test
was used to calculate statistical difference for in vitro tests. The anti-inflammatory activ-
ity and metabolism prognosis was done by Statistica software.

26
P. PATHAK ET AL.
2-(4-bromophenyl)-3-(5-phenyl-1,3,4-thiadiazol-2-yl)thiazolidin-4-one (4a)
Physical state: Light yellow powder; Yield 82%; Mol wt:418.33; mp 186–188 ꢂC; Rf: 0.88
(benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR Spectra
(KBr) in cmꢀ1: 2923 (N–CH–Sstretch, thiazolidinone), 1618 (C¼Ostretch), 1569 (C¼C
ringstretch, Ar), 1517–1431 (–C¼Nstretch), 1400–1089 (–C–H in planedef, Ar), 1385
(C¼Cstretch), 1239 (C–Nstretch), 1176 (N–Nstretch), 695 (C–S–Cstretch, thiadizolestretch), 616
1
(C–Brstretch); H-NMR (400 MHz, DMSO-d6, TMS) d ppm: 3.17 (dd, 2H, CH2, thiazoli-
dinone ring), 5.98 (s, 1H, CH, thiazolidinone ring), 7.17–7.19 (d, 1–H, CH, Br-Ph),
7.22–7.25 (d, 1H, CH, Ph), 7.27–7.28 (d, 1H, CH, Br-Ph), 7.36–7.36 (d, 1H, CH, Br-
Ph), 7.38–7.39 (d, 1H, CH, Ph), 7.46–7.47 (d, 1H, CH, Ph); 13C NMR (100 MHz,
CDCl3) d ppm: 170.7, 165.5, 161.3, 136.0, 131.5, 130.2, 130.1, 128.9, 126.6, 120.9, 68.7,
34.0; Mass: 418.96 (M þ H)þ; Elemental analysis for C17H12BrN3OS2, Calculated: C,
48.81; H, 2.89; N, 10.05. Found: C, 48.65; H, 2.59; N, 10.18.
2-(4-bromophenyl)-3-(5-(4-nitrophenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-one(4b)
Physical state: Yellowish white powder; Yield 80%; Mol wt: 463.33; mp 187–189 ꢂC; Rf:
0.86 (benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR Spectra
(KBr) in cmꢀ1: 3272 (N–CH–Sstretch, thiazolidinone), 2297 (C–Hstretch, Ar), 1627
(C¼Ostretch), 1627–1483 (–C¼Nstretch), 1570 (C¼C ringstretch, Ar), 1400–1093 (–C–H in
planedef, Ar), 1385 (NO2 stretch), 1235 (C–Nstretch), 1173 (N–Nstretch), 696 (C–S–Cstretch
,
1
thiadizole), 638 (C–Brstretch). H-NMR (400 MHz, DMSO-d6, TMS) d ppm: 3.18 (dd,
2H, CH2, thiazolidinone ring), 5.90 (s, 1H, CH, thiazolidinone ring), 7.49–7.50 (d, 1H,
CH, Br-Ph), 7.52–7.54 (d, 1H, CH, Br-Ph), 7.56–7.57 (d, 1H, CH, Br-Ph), 7.83 (d, 1H,
CH, NO2-Ph), 7.85 (d, 1H, CH, NO2-Ph), 7.93–7.94 (d, 1H, CH, NO2-Ph); 13C NMR
(100 MHz, CDCl3) d ppm: 174.2, 171.1, 163.2, 139.6, 138.2, 135.5, 134.9, 128.6, 128.4,
124.6, 124.1, 121.6, 68.7, 34.0; Mass Spectra: 463.94 (M þ H)þ; Elemental analysis for
C17H11BrN4O3S2, Calculated: C, 44.07; H, 2.39; N, 12.09; Found: C, 44.21; H, 2.16;
N, 12.14.
2-(4-bromophenyl)-3-(5-(4-hydroxyphenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-
one (4c)
Physical state: Yellowish powder; Yield 77%; Mol wt: 434.96; mp 188–190 ꢂC; Rf: 0.88
(benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1
:
2919 (N–CH–Sstretch
,
thiazolidinone), 1623 (C¼Ostretch), 1583
(C¼Cstretch, Ar), 1500–1435 (–C¼Nstretch), 1400–1083 (–C–H in planedef, Ar), 1247
(C–OHstretch, Ar), 1154 (C–Nstretch), 1114 (N–Nstretch), 688 (C–S–C thiadizolestretch), 660
1
(C–Brstretch): H-NMR (400 MHz, DMSO-d6, TMS) d ppm: 3.82, 3.94 (dd, 2H, CH2,
thiazolidinone ring), 6.24 (s, 1H, CH, thiazolidinone ring), 6.61–6.63 (d, 1H, CH,
hydroxy-Ph), 7.14–7.16 (d, 1H, CH, hydroxy-Ph), 7.36–7.38 (d, 1 H, CH, Br-Ph),
7.42–7.44 (d, 1H, CH, hydroxy-Ph), 7.50–7.55 (d, 1–H, CH, Br-Ph), 7.77–7.79 (d, 1 H,
CH, Br-Ph); 13C NMR (100 MHz, CDCl3) d ppm: 170.7, 165.3, 159.6, 154.0, 136.0,
131.5, 129.1, 128.9, 122.3, 120.9, 115.0, 68.7, 34.0; Mass Spectra: 355.04 (M þ H)þ;

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SYNTHETIC COMMUNICATIONSV
27
Elemental analysis for C17H12BrN3O2S2, Calculated: C, 47.01; H, 2.79; N, 9.67; Found:
C, 47.21; H, 2.51; N, 9.14.
2-(4-bromophenyl)-3-(5-(4-methoxyphenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-
one (4d)
Physical state: Yellowish powder; Yield 83%; Mol wt: 448.36; mp 196–198 ꢂC; Rf: 0.90
(benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1
:
2920 (N–CH–Sstretch
,
thiazolidinone), 1624 (C¼Ostretch), 1584
(C¼Cstretch, Ar), 1501–1435 (–C¼Nstretch), 1400–1080 (C–H in planedef, Ar),1247
(C–Nstretch), 1211 (OCH3 stretch, Ar), 1154 (N–Nstretch), 688 (C–S–Cstretch, thiadizole). 660
1
(C–Brstretch); H-NMR (400 MHz, DMSO-d6, TMS) d ppm: 3.21, 3.24 (dd, 2H, CH2,
thiazolidinone ring), 3.64 (s, 3H, OCH3), 5.95 (s, 1H, CH, thiazolidinone ring),
7.04–7.06 (d, 1H, CH, Br-Ph), 7.10–7.12 (d, 1H, CH, methoxybenzene), 7.14–7.20 (d,
1H, CH, methoxybenzene), 7.52–7.54 (d, 1H, CH, methoxybenzene), 7.61–7.66 (d, 1H,
CH, Br-Ph), 7.83–7.85 (d, 1H, CH, Br-Ph); 13C NMR (100 MHz, CDCl3) d ppm: 170.7,
165.3, 160.4, 136.0, 131.5, 128.5, 128.4, 122.0, 120.9, 114.9, 68.7, 55.7, 34.0; Mass: 446.97
(M þ H)þ;. Elemental analysis for C18H14BrN3O2S2, Calculated: C, 48.22; H, 3.15; N,
7.14; Found: C, 48.10; H, 3.12; N, 7.10.
2-(4-bromophenyl)-3-(5-(4-chlorophenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-
one (4e)
Physical state: Yellowish powder; Yield: 79%; Mol wt: 452.78; mp 156–158 ꢂC; Rf: 0.88
(benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1: 2923 (N–CH–Sstretch, thiazolidinone), 1618 (C¼Ostretch), 1569 (C¼C
ringstretch, Ar), 1517–1431 (–C¼Nstretch), 1400–1089 (–C–H in planedef, Ar), 1239
(C–Nstretch), 1176 (N–Nstretch), 754 (C–Clstretch), 695 (C–S–Cstretch, thiadizole), 616
1
(C–Brstretch); H-NMR (400 MHz, DMSO-d6, TMS) d ppm: 3.90, 3.92 (dd, 2H, CH2,
thiazolidinone ring), 5.94 (s, 1H, CH, thiazolidinone ring), 7.31–7.33 (d, 1H, CH, Cl-
Ph), 7.35–7.37 (d, 1H, CH, Cl-Ph), 7.44–7.45 (d, 1H, CH, Cl-Ph), 7.59–7.63 (d, 1H, CH,
Br-Ph), 7.67–7.65 (d, 1H, CH, Br-Ph); 13C NMR (100 MHz, CDCl3) d ppm: 170.8,
165.3, 153.8, 136.5, 136.0, 131.5, 128.9, 128.6, 127.8, 126.4, 120.9, 68.7, 34.0; Mass
Spectra: 452.92 (M þ H)þ; Elemental analysis for C17H11BrClN3OS2, Calculated: C,
45.10; H, 2.45; N, 9.28; Found: C, 45.10; H, 2.22; N, 9.10.
2-(2-chlorophenyl)-3-(5-phenyl-1,3,4-thiadiazol-2-yl)thiazolidin-4-one (4f)
Physical state: Yellowish powder; Yield: 373.88%; Mol wt: 452.78; mp 171–173 ꢂC; Rf:
0.93 (benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1: 3378 (N–CH–Sstretch, thiazolidinone), 1627 (C¼Ostretch), 1576 Ar (C¼C
ringstretch), 1527–1426 (–C¼N ringstretch), 1400–1107 (–CH in planedef, Ar), 1239
1
(C–Nstretch), 1107 (N–Nstretch), 734 (C–Clstretch), 693 (C–S–C thiadizolestretch); H-NMR
(400 MHz, DMSO-d6, TMS) d ppm: 3.14, 3.15 (dd, 2H, CH2, thiazolidinone ring), 5.96
(s, 1H, CH, thiazolidinone ring), 7.17–7.19 (d, 1H, CH, Ph), 7.24–7.26 (d, 1H, CH, Ph),

28
P. PATHAK ET AL.
7.34–7.36 (d, 1H, CH, Cl-Ph), 7.40–7.42 (d, 1H, CH, Ph), 7.75 (d, 1H, CH, Cl-Ph),
7.79–7.83 (d, 1H, CH, Cl-Ph); 13C NMR (100 MHz, CDCl3) d ppm: 170.2, 164.5, 161.0,
137.0, 132.1, 130.2, 130.1, 129.9, 129.1, 128.7, 126.6, 65.0, 34.0; Mass: 373.01 (M þ H)þ;
Elemental analysis for C17H12ClN3OS2, Calculated: C, 54.61; H, 3.24; N, 11.24; Found:
C, 54.21; H, 3.22; N, 11.10.
2-(2-chlorophenyl)-3-(5-(4-nitrophenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-one (4g)
Physical state: Yellowish white powder; Yield: 78%; Mol wt: 418.88; mp 176–178 ꢂC; Rf:
0.95 (benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1
:
2956 (N–CH–Sstretch
,
thiazolidinone), 1622 (C¼Ostretch), 1576
(C¼Cstretch, Ar), 1528–1429 (–C¼Nstretch), 1400–1095 (–CH in planedef), 1347 (NO2
stretch), 1239 (C–Nstretch), 1158 (N–Nstretch), 833 (C–Clstretch), 735 (C–S–Cstretch, thiadi-
1
zole); H-NMR (400 MHz, DMSO-d6, TMS) d ppm 3.38–3.43 (dd, 2H, CH2, thiazolidi-
none ring), 5.97 (s, 1H, CH, thiazolidinone ring), 7.16–7.18 (d, 1H, CH, Cl-Ph),
7.43–7.45 (d, 1H, CH, Cl-Ph), 7.51–7.53 (d, 1H, CH, Cl-Ph), 7.92–7.94 (d, 1H, CH,
No2-Ph), 8.07–8.08 (d, 1H, CH, No2-Ph), 8.65–8.68 (d, 1H, CH, No2-Ph); 13C NMR
(100 MHz, CDCl3) d ppm: 174.5, 171.2, 163.4, 134.5, 130.2, 130.1, 128.7, 128.4, 124.5,
102.5, 67.2, 34.0; Mass: 418 (M þ H)þ; Elemental analysis for C17H11ClN4O3S2,
Calculated: C, 48.75; H, 2.65; N, 13.38; Found: C, 48.14; H, 2.52; N, 13.42.
2-(2-chlorophenyl)-3-(5-(4-hydroxyphenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-
one (4h)
Physical state: Yellow powder; Yield: 81%; Mol wt: 389.88; mp 188–190 ꢂC; Rf: 0.92
(benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1
(C¼Cstretch
(C–OHstretch
:
2921 (N–CH–Sstretch
,
thiazolidinone), 1609 (C¼Ostretch), 1569
,
Ar), 1516–1429 (–CNstretch), 1400–1091 (–CH in planedef). 1343
Ar), 1236 (C–Nstretch), 1175 (N–Nstretch),751 (C–Clstretch), 692
,
1
(C–S–Cstretch, thiadizole); H NMR (400 MHz, DMSO-d6, TMS) d ppm: 3.98–3.99 (dd,
2H, CH2, thiazolidinone ring), 5.92 (s, H, CH, thiazolidinone ring), 6.41 (s, 1H, OH,
Ar), 7.36–7.36 (d, 1H, CH, Cl-Ph), 7.38–7.38 (d, 1H, CH, hydroxyl-Ph), 7.39-7.75 (d,
1H, CH, Cl-Ph), 8.21–8.21 (d, 1H, CH, hydroxyl-Ph); 13C NMR (100 MHz, CDCl3) d
ppm: 174.2, 171.1, 163.2, 139.6, 138.2, 135.5, 134.9, 128.6, 128.4, 124.6, 124.1, 131.6,
68.7, 34.0; Mass: 389.01 (M þ H)þ; Elemental analysis for C17H11ClN3O2S2, Calculated:
C, 52.37; H, 3.10; N, 9.09; Found: C, 52.38; H,3.12; N, 9.40.
2-(2-chlorophenyl)-3-(5-(4-methoxyphenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-
one (4i)
Physical state: Yellow powder; Yield: 78%; Mol wt: 403.91; mp 171–173 ꢂC; Rf: 0.93
(benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1: 2920 (N–CH–S thiazolidinonestretch), 1619(C¼Ostretch), 1569 (C¼Cstretch
,
Ar), 1517–1431(–CNstretch), 1400–1090 (–CH in planedef), 1274 (OCH3 stretch, Ar), 1236
(C–Nstretch), 1175 (N–Nstretch), 823, 752 (C–Clstretch), 689 (C–S–Cstretch, thiadizole);

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SYNTHETIC COMMUNICATIONSV
29
1H NMR (400 MHz, DMSO-d6, TMS) d ppm: 3. 98, 3. 99 (dd, 2H, CH2, thiazolidinone
ring), 3.46 (s, 3H, OCH3), 5.96 (s, 1H, CH, thiazolidinone ring), 6.36–7.19 (d, 1H, CH,
Cl-Ph), 7.24–7.25 (d, 1H, CH, Cl-Ph), 7.28–7.30 (d, 1H, CH, Cl-Ph), 7.72–7.98 (d, 1H,
CH, methoxy-Ph), 8.15–8.16 (d, 1H, CH, methoxy-Ph), 8.31–8.33 (d, 1H, CH, methoxy-
Ph); 13C NMR (100 MHz, CDCl3) d ppm: 170.2, 163.2, 161.5, 160.9, 137.0, 132.2, 129.8,
129.4, 129.3, 128.7, 128.6, 122.0, 114.9, 65.8, 55.7, 34.0; Mass: 403.02 (M þ H)þ;
Elemental analysis for C18H14ClN3O2S2, Calculated: C, 53.53; H, 3.49; N, 10.40; Found:
C, 53.18; H, 3.08; N, 10.12.
2-(2-chlorophenyl)-3-(5-(4-chlorophenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-one (4j)
Physical state: Light yellow powder; Yield: 75%; Mol wt: 408.32; mp 176–178 ꢂC; Rf:
0.91 (benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1
(C¼Cstretch
:
2920 (N–CH–Sstretch
,
thiazolidinone), 1614 (C¼Ostretch), 1569
,
Ar), 1516–1429 (–CNstretch), 1400–1090 (–CH in planedef), 1235
1
(C–Nstretch), 1175 (N–Nstretch), 757 (C–Clstretch), 689 (C–S–Cstretch, thiadizole); H NMR
(400 MHz, DMSO-d6, TMS) d ppm: 3.98–3.99 (dd, 2H, CH2, thiazolidinone ring), 5.92
(s, 1H, CH, thiazolidinone ring), 7.04–7.05 (d, 1H, CH, Cl-Ph), 7.32–7.33 (d, 1H, CH,
Cl-Ph), 7.34–7.34 (d, 1H, CH, Cl-Ph), 7.35–7.36 (d, 1H, CH, Cl-Ph), 7.74 (d, 1H, CH,
Cl-Ph); 13C NMR (100 MHz, CDCl3) d ppm: 170.2, 163.7, 160.3, 137.1 136.6, 132.2,
129.8, 129.4, 128.7, 128.6, 127.8, 126.4, 65.8, 34.0; Mass Spectra: 406.97 (M þ H)þ;
Elemental analysis for C18H14ClN3O2S2, Calculated: C, 50.01; H, 2.72; N, 10.29; Found:
C, 50.18; H, 2.75; N, 10.22.
2-(4-fluorophenyl)-5-methyl-3-(5-phenyl-1,3,4-thiadiazol-2-yl)thiazolidin-4-one (4k)
Physical state: Light yellow powder; Yield: 79%; Mol wt: 357.43; mp 167–169 ꢂC; Rf:
0.82 (benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra
(KBr) in cmꢀ1
:
2919 (N–CH–Sstretch
,
thiazolidinone), 1620 (C¼Ostretch), 1581
(C¼Cstretch, Ar), 1498–1429 (–CNstretch), 1400–1080 (–CH in planedef), 1367 (CH3
stretch), 1253 (C–Nstretch), 1211 (Ar–Hstretch), 1155 (N–Nstretch), 1115 (C–Fstretch), 692
1
(C–S–Cstretch, thiadizole); H-NMR (400 MHz, DMSO-d6, TMS) d ppm: 1.48–1.51 (d,
3H, CH3), 3.28-3.49 (m, 1H, CH, thiazolidinone ring), 5.97 (s, 1 H, CH, thiazolidinone
ring), 6.25–6.55 (d, 1H, CH, Ph), 6.69–6.74 (d, 1H, CH, Ph), 6.75-6.83 (d, 1H, CH, F-
Ph), 7.04–7.078 (d, 1H, CH, F-Ph), 7.11–7.13 (d, 1H, CH, Ph), 7.20–7.21 (d, 1 H, CH,
Ph); 13C NMR (100 MHz, CDCl3) d ppm: 169.0, 166.4, 161.9, 161.4, 132.9, 130.2, 130.1,
128.9, 126.6, 115.7, 42.1, 17.9; Mass Spectra: 357.04 (M þ H)þ; Elemental analysis for
C17H12FN3OS2, Calculated: C, 58.20; H, 3.80; N, 11.31; Found: C, 58.40; H, 3.16;
N, 11.12.
2-(4-fluorophenyl)-5-methyl-3-(5-(4-nitrophenyl)-1,3,4-thiadiazol-2-yl)thiazolidin-4-
one (4 l)
Physical state: Light brown powder; Yield: 82%; Mol wt: 416.45; mp 232-234 ꢂC; Rf: 0.91
(benzene: ethyl acetate); Solubility: Ethanol, Chloroform, DMSO-d6; FT-IR spectra