Synthesis and biological evaluation of some pyrazole derivatives as anti-inflammatory-Antibacterial agents

Article abstract of DOI:10.1007/s00044-011-9853-4

The present article describes the synthesis of two novel series of thiosemicarbazones 3 and thiazolylhydrazinomethylidenepyrazoles 5. All the newly synthesized target compounds (3a-e and 5a-o) were screened for their in vivo anti-inflammatory (AI) activit

Full text of DOI:10.1007/s00044-011-9853-4

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-011-9853-4
ORIGINAL RESEARCH
Synthesis and biological evaluation of some pyrazole derivatives
as anti-inflammatory–antibacterial agents
•
Pawan Kumar Navneet Chandak Pawan Kaushik
•
•
•
•
•
Chetan Sharma Dhirender Kaushik Kamal R. Aneja
Pawan K. Sharma
Received: 9 March 2011 / Accepted: 28 October 2011
Ó Springer Science+Business Media, LLC 2011
Abstract The present article describes the synthesis of two
novel series of thiosemicarbazones 3 and thiazolylhy-
drazinomethylidenepyrazoles 5. All the newly synthesized
target compounds (3a–e and 5a–o) were screened for their in
vivo anti-inflammatory (AI) activity using carrageenan-
induced rat paw edema assay and in vitro antibacterial
activity against two Gram-positive and two Gram-negative
bacteria. Eight compounds (3b–d, 5b, 5e, 5f, 5i, and 5o)
showed consistently excellent AI activity (C70% inhibi-
tion), at 3 and 4 h after the carrageenan injection, compa-
rable to that of standard drug indomethacin (78%) whereas
the remaining twelve compounds have shown significant
activity with 57–75% inhibition after 3 h and 56–63% inhi-
bition after 4 h. All the tested compounds showed moderate
antibacterial properties.
evolution leading to the emergence of more efficacious
classes of drugs. Since the discovery of aspirin, much efforts
have been devoted to the development of non-steroidal anti-
inflammatory drugs (NSAIDs), which are among the most
widely prescribed medication in clinical practice despite
their well documented renal and gastrointestinal (GI) side
effects. Conventional NSAIDs exert non-selective inhibition
(Dannhardt and Keifer, 2001) of COX enzymes, the agents
which catalyze the rate-limiting step in the formation of
prostanoids from arachidonic acid. Such indiscriminate
inhibition of COX-1 as well as COX-2 has been blamed for
high incidence of GI irritation or, in the worst case, devel-
opment of life threatening GI ulcers and bleeding in long
term users of NSAIDs. Consequently, a second generation
of NSAIDs has been developed which selectively inhibit
COX-2. Being selective COX-2 inhibitors, these are expec-
ted to achieve the same anti-inflammatory efficacy as tradi-
tional NSAIDs but minimize the risk of unwanted GI
complications. Though the selective COX-2 inhibitors have
minimal toxicity in the gastrointestinal tract, theseagentscan
produce severe side effects in renal, hepatic, and cardio-
vascular systems. The recent withdrawal of valdecoxib
(Nussmeier et al., 2005), and rofecoxib (Scheen, 2004) has
focused attention on the adverse cardiovascular effects of
selective COX-2 inhibitors. Thus, search for novel anti-
inflammatory drugs with minimal GI side effects and high
safety margin is still warranted.
Keywords Thiosemicarbazones ꢀ Thiazoles ꢀ Pyrazoles ꢀ
Anti-inflammatory activity ꢀ Antibacterial activity
Introduction
The development of an effective therapeutic agent for the
management of inflammation has undergone continual
P. Kumar ꢀ N. Chandak ꢀ P. K. Sharma (&)
Department of Chemistry, Kurukshetra University,
Kurukshetra 136119, India
Pyrazole moiety makes the core structure of various drugs
such as difenamizole (Kameyama et al., 1978; Kameyama
and Nabeshima, 1978), celecoxib (Penning et al., 1997)
tepoxalin, (Anderson et al., 1990) etc. Besides this, there are
several reports in the literature on the anti-inflammatory
(Bekhit et al., 2003; Banoglu et al., 2004; Bekhit et al.,
e-mail: pksharma@kuk.ac.in
P. Kaushik ꢀ D. Kaushik
Institute of Pharmaceutical Sciences, Kurukshetra University,
Kurukshetra 136119, India
C. Sharma ꢀ K. R. Aneja
´
2005; Rosati et al., 2007; Szabo et al., 2008) and antimi-
crobial properties (Foks et al., 2005; Shamroukh et al., 2007;
Department of Microbiology, Kurukshetra University,
Kurukshetra 136119, India
123

Med Chem Res
Prakash et al., 2008) of pyrazoles. However studies inves-
tigating the potential of pyrazole derivatives as dual anti-
microbial–anti-inflammatory agents has only recently been
initiated (Bekhit and Fahmy, 2003; Bekhit and Abdel-
Azeim, 2004; Bekhit et al., 2005; Bekhit et al., 2006; Bekhit
et al., 2009). Thiazoles and their derivatives are also known
to exhibit antimicrobial (Bondock et al., 2007; Karegoudar
et al., 2008) as well as anti-inflammatory activity (Kalk-
hambkar et al., 2007; Kouatly et al., 2009; Giri et al., 2009).
Since the combination of pharmacophores on the same
scaffold is a well established approach to the synthesis of
more potent drugs (Pillai et al., 2003; Venkatachalam et al.,
2006), we decided to incorporate pyrazole moiety and thiazole
ring in the same molecule while retaining the benzenesul-
fonamide group in an effort to synthesize new compounds
with dual anti-inflammatory–antibacterial potential.
Results and discussion
Chemistry
The reaction of a-haloketones with a thioamide has been
the most important method for the thiazole synthesis ever
since it was introduced by Hantzsch and Weber (1887).
Corresponding to the Hantzsch thiazole synthesis, the
present synthesis of thiazolylhydrazinomethylidenepyr-
azoles 5 consists of the condensation of a-bromoketones 4
with thiosemicarbazones 3 in refluxing EtOH:THF in the
presence of sodium acetate (Scheme 1).
Accordingly 4-formylpyrazoles (1a–e) (Bekhit et al.,
2009; Sharma et al., 2011) were treated with thiosemicar-
bazide 2 in the presence of catalytic amount of acetic acid
to afford the corresponding thiosemicarbazones 3 which on
subsequent reaction with various a-bromoketones 4 affor-
ded the target thiazolylhydrazinomethylidenepyrazoles 5.
Spectral data (1H NMR, 13C NMR, IR and mass) of the
newly synthesized compounds were in full agreement
with the proposed structures. In general, the characteristic
Motivated by these findings coupled with our ongoing
program in the field of pyrazoles and other heterocyclic
compounds (Sawhney and Sharma, 1993; Sharma and
Sawhney, 1993; Sharma and Sawhney, 1997; Sharma et al.,
1998, 2010, 2011), as anti-inflammatory agents, it was
decided to synthesize two novel series of thiosemicarba-
zones 3 and thiazolylhydrazinomethylidenepyrazoles 5
with a potential to act as dual anti-inflammatory–antibac-
terial agents with minimal GI side effects and high safety
margin.
1
signals in H NMR of target thiosemicarbazones 3 are the
presence of three exchangeable singlets in the range of d
11.41–11.43, d 8.26–8.32 and d 7.77–7.82 corresponding
to SH, NH and =NH protons indicating that in solution
CSNH2 moiety may exist in its tautomeric form
H2NO2S
R
N
N
EtOH/H
reflux
NH2
H
N
H2NO2S
N
N
H2N
+
H
N
R
H
S
H2N
N
H
O
S
1
2
a
c
e
3
b
d
CH3 OCH3
R H F Cl
H2NO2S
N
O
N
Br
S
H
CH3COONa/EtOH:THF
reflux
N
3
+
N
N
H
R
R1
R1
a
b
4
c
CH3
R1 H Cl
5
5
R
a
b
c
d
F
e
f
g
h
i
j
k
l
m
n
o
H
H
H
H
F
F
Cl Cl
Cl CH3 CH3 CH3 OCH3 OCH3 OCH3
Cl CH3 Cl CH3
R1
Cl CH3
H
Cl CH3
H
Cl CH3
H
H
Scheme 1 Synthesis of target thiosemicarbazones 3 and thiazolylhydrazinomethylidenepyrazoles 5
123

Med Chem Res
(HS–C=NH). Another exchangeable singlet integrating for
two protons in the range of d 7.46–7.49 was ascribed
to NH2 of SO2NH2 group. The 1H NMR spectra of
thiazolylhydrazinomethylidenepyrazoles 5 displayed an
exchangeable singlet in the range of d 11.99–12.05 corre-
sponding to NH besides a singlet for NH2 of SO2NH2
group in the range of d 7.44–7.49. A singlet in the range of
d 7.20–7.40 is attributed to C5-proton of thiazole ring. In
some of the compounds, this C5-proton of thiazole is
merged with other aromatic protons.
1962). The protocol of animal experiments has been
approved by the Institutional Animal Ethics Committee
(IAEC). Each test compound was dosed orally (50 mg/kg
body weight) 30 min prior to induction of inflammation by
carrageenan injection. Indomethacin was used as a refer-
ence anti-inflammatory drug at a dose of 10 mg/kg, i.p. The
anti-inflammatory activity was then calculated at hourly
intervals 1–4 h after induction and presented in Table 1 as
the mean paw volume (ml) as well as the percentage anti-
inflammatory activity (AI%).
Among twenty compounds (3a–e and 5a–o) tested, eight
compounds (3b–d, 5b, 5e, 5f, 5i, and 5o) showed consis-
tently excellent AI activity (C70% inhibition) 3 and 4 h after
the carrageenan injection comparable to that of standarddrug
indomethacin (78%), whereas the remaining twelve com-
pounds have shown significant activity with 57–75% inhi-
bition after 3 h and 56–63% inhibition after 4 h.
Biological evaluation
In vivo anti-inflammatory activity
All the newly synthesized thiosemicarbazones 3a–e and
thiazolylhydrazinomethylidenepyrazoles 5a–o were evalu-
ated for their in vivo anti-inflammatory activity by carra-
geenan induced rat paw edema method (Winter et al.,
In general, compounds containing a halogen substituent
showed better activity as compared to non-halogen-containing
Table 1 In vivo anti-inflammatory activity of compounds 3a–e and 5a–o
Compounda
Volume of edema (ml)b and %AIc
1 (h)
2 (h)
3 (h)
4 (h)
Control
0.53 0.01
2.18 0.09
2.20 0.07
2.30 0.03
Indomethacin
0.31 0.02** (41)c
0.34 0.08** (35)
0.40 0.03** (24)
0.35 0.04** (33)
0.36 0.06** (32)
0.38 0.06** (28)
0.35 0.06** (33)
0.36 0.04** (32)
0.38 0.03** (28)
0.47 0.01* (11)
0.34 0.01** (35)
0.35 0.05** (33)
0.41 0.03** (22)
0.38 0.06** (28)
0.50 0.03 (5)
0.45 0.07** (79)
0.88 0.06** (59)
0.53 0.08** (75)
0.51 0.08** (76)
0.58 0.07** (72)
0.52 0.03** (76)
0.62 0.07** (71)
0.58 0.07** (72)
0.75 0.10** (65)
0.87 0.06** (60)
1.53 0.02** (29)
0.59 0.03** (72)
0.81 0.06** (62)
0.70 0.10** (67)
0.83 0.03** (61)
0.87 0.06** (60)
0.86 0.05** (60)
0.58 0.07** (72)
0.73 0.05** (65)
0.72 0.06** (66)
0.75 0.08** (65)
0.48 0.09** (78)
0.71 0.09** (67)
0.58 0.07** (73)
0.50 0.03** (77)
0.55 0.07** (75)
0.89 0.08** (59)
0.67 0.08** (69)
0.55 0.07** (75)
0.95 0.10** (57)
0.76 0.04** (65)
0.58 0.07** (73)
0.58 0.07** (73)
0.93 0.12** (57)
0.58 0.07** (73)
0.66 0.05** (70)
0.56 0.04** (75)
0.86 0.06** (60)
0.56 0.04** (75)
0.87 0.06** (61)
0.67 0.03** (69)
0.61 0.07** (72)
0.50 0.05** (78)
0.84 0.05** (63)
0.57 0.05** (75)
0.66 0.01** (71)
0.68 0.01** (70)
0.66 0.06** (71)
0.64 0.01** (72)
0.68 0.01** (70)
0.92 0.05** (60)
1.00 0.04* (56)
0.57 0.06** (75)
0.67 0.06** (70)
1.00 0.10** (56)
0.95 0.08** (58)
0.60 0.07** (73)
1.00 0.14* (56)
0.97 0.02* (57)
0.88 0.06** (61)
0.88 0.04** (61)
0.67 0.06** (71)
0.68 0.03** (70)
3a
3b
3c
3d
3e
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
0.35 0.03** (33)
0.36 0.01** (32)
0.40 0.09** (24)
0.36 0.02** (32)
0.36 0.05** (32)
0.33 0.06** (37)
5k
5l
5m
5n
5o
a
Dose levels: test compounds (50 mg/kg body wt.), indomethacin (10 mg/kg body wt.)
b
c
Values are expressed as mean SEM and analyzed by ANOVA
Values in parentheses (percentage anti-inflammatory activity, AI%)
*Significantly different compared to respective control values, P \ 0.05
**Significantly different compared to respective control values, P \ 0.01
123

Med Chem Res
In vitro antibacterial activity
compounds. For instance, six of the eight compounds con-
taining chlorine (Cl) as one of the substituents (3c, 5b, 5e, 5h,
5i, and 5n) showed excellent activity (C70% inhibition) when
measured 3 h after the carrageenan injection. The best com-
pound in each series (3b, 5e) in terms of AI activity after 4 h
contains a fluoro (F) substituent at position-4 of the phenyl ring
that is attached to the C-3 of the pyrazole moiety. In general,
thiosemicarbazones 3a–e showed better AI activity as com-
pared to the thiazoles derived from them. Thus, incorporation of
thioamide part of the thiosemicarbazones 3a–e into a thiazole
nucleus (5a–o) neither has a beneficial effect nor a detrimental
effect on the AI activity. Four (3b–d) of the five thiosemicar-
bazones (3a–e) showed excellent AI activity comparable to that
of the standard drug indomethacin. Out of four compounds (3e,
and 5m–o) containing a methoxy substituent, three compounds
(3e, 5n, and 5o) showed excellent AI activity (C70% inhibi-
tion) after 4 h. These results are in accordance with our earlier
observations (Sharma and Sawhney, 1997; Sharmaet al., 1998)
claiming that the compounds with Cl (or F) and methoxy sub-
stituents show higher activity. Consistently, excellent AI
activity up to 4 h suggests that these compounds do not get
easily metabolized in the system.
All the target compounds were evaluated for their in vitro
antibacterial activity using agar well diffusion method
(Ahmad and Beg, 2001) against Staphylococcus aureus
(MTCC 96) and Bacillus subtilis (MTCC 121) representing
Gram-positive bacteria, and Escherichia coli (MTCC
1652) and Pseudomonas aeruginosa (MTCC 741) repre-
senting Gram-negative bacteria (Table 2). Ciprofloxacin
was used as the reference drug. Antibacterial activity,
indicated by an inhibition zone surrounding the well con-
taining the compounds, was recorded if the zone of inhi-
bition was greater than 8 mm. MIC of various compounds
against bacterial strains was tested through a macrodilution
tube method as recommended by National Committee for
Clinical Laboratory Standards (NCCLS) (Andrews, 2001)
(Table 2).
Results revealed that all tested compounds 3a–3e and
5a–5o possessed moderate to good antibacterial activity
against Gram-positive bacteria (S. aureus, B. subtilis)
(Table 2). However, none of the compounds showed
activity against Gram-negative bacteria (E. coli and
Table 2 In vitro antibacterial activity of compounds 3a–e and 5a–o
Compounda
Diameter of growth of inhibition zone (mm)b
Minimum inhibitory concentration (MIC) (lg/ml)
S. aureus
B. subtilis
E. coli
P. aeruginosa
S. aureus
B. subtilis
Ciprofloxacin
26.3
17.0
15.6
14.0
16.3
13.6
14.3
13.6
15.0
14.6
14.3
15.6
13.3
14.6
15.3
15.3
14.6
13.6
15.3
13.6
20.6
25.6
19.6
15.3
13.6
14.3
15.0
14.6
15.3
14.6
16.6
13.3
14.3
15.6
15.0
14.6
13.6
15.3
14.0
15.6
14.3
17.3
25.0
–
23.3
–
5
128
5
64
3a
3b
3c
3d
3e
5a
5b
5c
5d
5e
5f
–
–
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
64
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
[128
128
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
5g
5h
5i
–
–
–
–
–
–
5j
–
–
5k
5l
–
–
–
–
5m
5n
5o
–
–
–
–
–
–
– No activity
a
Concentration 4.0 mg/ml
b
Values, including diameter of the well (8 mm), are means of three replicates
123

Med Chem Res
General procedure for the synthesis of
P. aeruginosa). On the basis of zone of inhibition against
the test bacterium, compounds 5o and 3a were found to
be the most active molecules and showed good antibac-
terial activity against Gram-positive bacteria (S. aureus,
B. subtilis). When compared with standard drug cipro-
floxacin which showed the zone of inhibition 26.3 mm
against S. aureus and 25.6 mm against B. subtilis, 3a was
found to be most effective against B. subtilis with zone of
inhibition 19.6 mm and 5o was found to be most effective
against S. aureus with zone of inhibition 20.6 mm
(Table 2).
thiosemicarbazones (3a–k)
To a solution of 4-formylpyrazole 1 (1.0 mmol) in ethanol
(10 ml), was added thiosemicarbazide (2, 1.0 mmol) fol-
lowed by 4–5 drops of glacial acetic acid. The resulting
reaction mixture was refluxed for 1 h, cooled to room
temperature, whereupon a solid material separated out that
was filtered, washed with water followed by ethanol, and
dried to afford the target thiosemicarbazones 3 as solid
material in excellent yield.
2-({1-[4-(Aminosulfonyl)phenyl]-3-phenyl-1H-pyrazol-4-
yl}methylidene)-1-hydrazinecarbothioamide 3a
Conclusion
M.p. 196–198°C, yield 90%; IR (KBr) cm-1: 3464, 3317
and 3124 (N–H stretch), 1597 (C=N stretch), 1543 (C=N
stretch), 1504 (N–H bend), 1335 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 11.41 (s, ex, 1H, NH/
SH/=NH), 9.30 (s, 1H, CH=N), 8.33 (s, ex, 1H, NH/SH/
=NH), 8.23 (s, 1H, pyrazole–H), 8.09 (d, 2H, J = 8.7 Hz,
Ar), 8.01 (d, 2H, J = 8.7 Hz, Ar), 7.81 (s, ex, 1H, NH/SH/
=NH), 7.69 (m, 2H, Ar), 7.52 (m, 3H, Ar), 7.48 (s, ex, 2H,
SO2NH2); 13C NMR (75.5 MHz, DMSO-d6): d 178.1,
152.5, 142.4, 141.5, 135.1, 132.2, 129.2, 128.6, 127.9,
118.9, 118.4; m/z 401 ([M?H]?, C17H16N6O2S2H? calcd.
401).
Twenty new compounds including five thiosemicarbazones
(3a–e) and fifteen thiazolylhydrazinomethylidenepyrazoles
(5a–o) were synthesized and evaluated for their in vivo anti-
inflammatory activity and in vitro antibacterial activity. In
general thiosemicarbazones (3a–e) showed better AI activity
as compared to the thiazolylhydrazinomethylidenepyrazoles
(5a–o) derived from them indicating that the thiazole ring,
derived from thiocarboxamide part of thiosemicarbazones
(3a–e), is capable of retaining the AI activity but not
advantageous. Four (3b–e) of the five thiosemicarbazones
and five of the fifteen thiazole containing pyrazole deriva-
tives (5b, 5e, 5f, 5i, and 5o) showed excellent AI activity
(C70% inhibition) 3 h as well as 4 h after the carrageenan
injection that is comparable to the standard drug indometh-
acin. However, none of the compounds was found to be
superior over the reference drug. Though the tested com-
pounds failed to give encouraging results in terms of their
antibacterial properties, the AI activity results are promising
and demand further investigations in this area.
2-({1-[4-(Aminosulfonyl)phenyl]-3-(4-fluorophenyl)-1H-
pyrazol-4-yl}methylidene)-1-hydrazinecarbothioamide 3b
M.p. 220–222°C, yield 94%; IR (KBr) cm-1: 3456, 3333
and 3163 (N–H stretch), 1597 (C=N stretch), 1543 (C=N
stretch), 1512 (N–H bend), 1342 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 11.43 (s, ex, 1H, NH/
SH/=NH), 9.27 (s, 1H, CH=N), 8.31 (s, ex, 1H, NH/SH/
=NH), 8.19 (s, 1H, pyrazole–H), 8.08 (d, 2H, J = 9.0 Hz,
Ar), 7.99 (d, 2H, J = 9.0 Hz, Ar), 7.77 (s, ex, 1H, NH/SH/
Experimental protocols
3
4
=NH), 7.74 (dd, JHH = 8.4 Hz, JHF = 5.4 Hz, 2H, Ar),
7.49 (s, ex, 2H, SO2NH2), 7.38 (t, 2H, J = 8.7 Hz, Ar); 13
NMR (75.5 MHz, DMSO-d6): 178.0, 162.8 (d,
C
Melting points were determined in open capillaries in
electrical apparatus and are uncorrected. IR spectra were
recorded on a Buck Scientific IR M500 instrument. The 1H
NMR and 13C NMR spectra were recorded on a Bruker
instrument at 300 MHz and 75.5 MHz, respectively. The d
values are given in ppm relative to tetramethylsilane as
internal standard (for 1H and 13C NMR). Mass spectra
(DART-MS) were recorded on a JEOL-AccuTOF JMS-
T100LC Mass spectrometer having a DART (direct anal-
ysis in real time) source in ES? mode. Exchangeable (ex)
protons were detected by disappearance of peaks upon D2O
d
1JCF = 246.0 Hz), 151.6, 142.4, 141.4, 135.0, 130.7 (d,
3JCF = 8.3 Hz), 128.6, 127.9, 118.9, 118.3, 116.2 (d,
2JCF = 21.1 Hz); m/z 419 ([M?H]?, C17H15FN6O2S2H?
calcd. 419).
2-({1-[4-(Aminosulfonyl)phenyl]-3-(4-chlorophenyl)-1H-
pyrazol-4-yl}methylidene)-1-hydrazinecarbothioamide 3c
M.p. 230–231°C, yield 91%; IR (KBr) cm-1: 3464, 3348
and 3163 (N–H stretch), 1597 (C=N stretch), 1543 (C=N
stretch), 1504 (N–H bend), 1335 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 11.43 (s, ex, 1H, NH/
1
addition. The purity of the compounds was checked by H
NMR. Iodine or UV lamp was used as a visualizing agent
for thin layer chromatography (TLC).
123

Med Chem Res
SH/=NH), 9.27 (s, 1H, CH=N), 8.30 (s, ex, 1H, NH/SH/
=NH), 8.20 (s, 1H, pyrazole–H), 8.09 (d, 2H, J = 8.7 Hz,
Ar), 8.01 (d, 2H, J = 8.7 Hz, Ar), 7.77 (s, ex, 1H, NH/SH/
=NH), 7.72 (d, 2H, J = 8.4 Hz, Ar), 7.58 (d, 2H,
J = 8.4 Hz, Ar), 7.48 (s, ex, 2H, SO2NH2); 13C NMR
(75.5 MHz, DMSO-d6): d 178.1, 151.2, 142.5, 141.2,
134.9, 134.1, 131.0, 130.3, 129.2, 128.8, 127.9, 119.0,
118.4; m/z 435 ([M?H]?, C17H15ClN6O2S2H? calcd. 435).
was crystallized from ethanol, to yield the target thiazo-
lylhydrazinomethylidenepyrazoles 5 as solid material.
4-(3-Phenyl-4-{[2-(4-phenyl-1,3-thiazol-2-
yl)hydrazono]methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5a
M.p. 230–232°C, yield 78%; IR (KBr) cm-1: 3410, 3333
and 3263 (N–H stretch), 1605 (C=N stretch), 1551 (C=N
stretch), 1504 (N–H bend), 1358 and 1142 (s, SO2 stretch)
cm-1; 1H NMR (300 MHz, DMSO-d6): d 12.04 (s, ex, 1H,
NH), 9.02 (s, 1H, CH=N), 8.23 (s, 1H, pyrazole–H), 8.19
(d, 2H, J = 8.7 Hz, Ar), 8.01 (d, 2H, J = 8.7 Hz, Ar),
7.80–7.86 (m, 4H, Ar), 7.53–7.55 (m, 3H, Ar), 7.48 (s, ex,
2H, SO2NH2), 7.40-7.43 (m, 2H, Ar), 7.37–7.38 (m, 2H,
Ar, thiazole–H); 13C NMR (75.5 MHz, DMSO-d6): d
168.3, 152.0, 150.8, 142.3, 141.5, 135.1, 134.7, 132.4,
129.1, 129.0, 128.4, 127.9, 127.8, 125.9, 119.1, 118.2,
2-({1-[4-(Aminosulfonyl)phenyl]-3-(4-methylphenyl)-1H-
pyrazol-4-yl}methylidene)-1-hydrazinecarbothioamide 3d
M.p. 218-220°C, yield 95%; IR (KBr) cm-1: 3464, 3348
and 3171 (N–H stretch), 1589 (C=N stretch), 1543 (C=N
stretch), 1504 (N–H bend), 1335 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 11.40 (s, ex, 1H, NH/
SH/=NH), 9.27 (s, 1H, CH=N), 8.32 (s, ex, 1H, NH/SH/
=NH), 8.21 (s, 1H, pyrazole–H), 8.07 (d, 2H, J = 8.7 Hz,
Ar), 8.01 (d, 2H, J = 8.7 Hz, Ar), 7.82 (s, ex, 1H, NH/SH/
=NH), 7.58 (d, 2H, J = 8.4 Hz, Ar), 7.49 (s, ex, 2H,
SO2NH2), 7.32 (d, 2H, J = 8.4 Hz, Ar), 2.37 (s, 3H, CH3);
13C NMR (75.5 MHz, DMSO-d6): d 178.0, 152.5, 142.3,
141.5, 138.8, 135.2, 129.8, 129.3, 128.5, 127.9, 118.8,
118.3, 21.3 (CH3); m/z 415 ([M?H]?, C18H18N6O2S2H?
calcd. 415).
103.9;
DART
MS
m/z
501.1160
[M?H]?,
C25H20N6O2S2H? calcd. 501.1162.
4-(4-{[2-(4-(4-Chlorophenyl)-1,3-thiazol-2-
yl)hydrazono]methyl}-3-phenyl-1H-pyrazol-1-
yl)benzenesulfonamide 5b
M.p. 228–230°C, yield 74%; IR (KBr) cm-1: 3456, 3310
and 3263 (N–H stretch), 1598 (C=N stretch), 1566 (C=N
stretch), 1504 (N–H bend), 1335 and 1149 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.04 (s, ex, 1H, NH),
9.02 (s, 1H, CH=N), 8.22 (s, 1H, pyrazole–H), 8.18 (d, 2H,
J = 8.7 Hz, Ar), 7.98 (d, 2H, J = 8.7 Hz, Ar), 7.85 (d, 2H,
J = 8.7 Hz, Ar), 7.79 (d, 2H, J = 8.7 Hz, Ar), 7.44–7.55
(m, 5H, Ar, SO2NH2), 7.37 (s, 1H, thiazole–H); 13C NMR
(75.5 MHz, DMSO-d6): d 168.5, 152.0, 149.6, 142.3,
141.5, 134.9, 134.0, 132.4, 129.08. 129.00, 128.5, 127.7,
127.6, 119.1, 118.1, 104.7; DART MS m/z 535.07425
[M?H]?, C25H19ClN6O2S2H? calcd. 535.0772.
2-({1-[4-(Aminosulfonyl)phenyl]-3-(4-methoxyphenyl)-1H-
pyrazol-4-yl}methylidene)-1-hydrazinecarbothioamide 3e
M.p. 221-223°C, yield 89%; IR (KBr) cm-1: 3458, 3333
and 3171 (N–H stretch), 1597 (C=N stretch), 1543 (C=N
stretch), 1506 (N–H bend), 1335 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 11.42 (s, ex, 1H, NH/
SH/=NH), 9.22 (s, 1H, CH=N), 8.26 (s, ex, 1H, NH/SH/
=NH), 8.20 (s, 1H, pyrazole–H), 8.08 (d, 2H, J = 8.7 Hz,
Ar), 7.99 (d, 2H, J = 8.7 Hz, Ar), 7.77 (s, ex, 1H, NH/SH/
=NH), 7.62 (d, 2H, J = 8.4 Hz, Ar), 7.46 (s, ex, 2H,
SO2NH2), 7.07 (d, 2H, J = 8.4 Hz, Ar), 3.82 (s, 3H,
OCH3); 13C NMR (75.5 MHz, DMSO-d6): d 178.1, 160.2,
152.4, 142.3, 141.5, 135.4, 130.0, 128.4, 127.8, 124.5,
118.8, 118.1, 114.6, 55.7 (OCH3); m/z 431 ([M?H]?,
C18H18N6O2S2H? calcd. 431).
4-(4-{[2-(4-(4-Methylphenyl)-1,3-thiazol-2-
yl)hydrazono]methyl}-3-phenyl-1H-pyrazol-1-
yl)benzenesulfonamide 5c
M.p. 185–186°C, yield 80%; IR (KBr) cm-1: 3425, 3271
and 3143 (N–H stretch), 1589 (C=N stretch), 1558 (C=N
stretch), 1497 (N–H bend) 1335 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 11.99 (bs, ex, 1H, NH),
9.01 (s, 1H, CH=N), 8.23 (s, 1H, pyrazole–H), 8.18 (d, 2H,
J = 8.7 Hz, Ar), 7.99 (d, 2H, J = 8.7 Hz, Ar), 7.81 (d, 2H,
J = 8.7 Hz, Ar), 7.73 (d, 2H, J = 8.7 Hz, Ar), 7.48–7.55
(m, 5H, Ar, SO2NH2), 7.19–7.22 (m, 3H, thiazole–H, Ar),
2.31 (s, 3H, CH3); 13C NMR (75.5 MHz, DMSO-d6): d
168.2, 152.0, 142.3, 141.5, 137.2, 134.6, 132.5, 132.4,
129.6, 129.0, 128.9, 128.4, 127.7, 125.9, 119.1, 118.2,
General procedure for the preparation of
thiazolylhydrazinomethylidenepyrazoles (5a–o)
To a solution of thiosemicarbazone (3, 1.0 mmol) in
THF:EtOH (80 ml), was added a-bromoketone (4,
1.0 mmol) followed by a sodium acetate (1.0 mmol). The
resulting reaction mixture was refluxed for 6 h, cooled to
room temperature, whereupon a solid material was sepa-
rated out, which was filtered to afford crude material that
123

Med Chem Res
103.0, 21.2 (CH3); DART MS m/z 515.1341 [M?H]?,
(d, 1JCF = 246.6 Hz), 150.9, 142.3, 141.4, 137.2, 131.1 (d,
3JCF = 8.3 Hz), 129.0, 127.8, 125.9, 119.0, 118.1, 115.9
C26H22N6O2S2H? calcd. 515.1318.
2
(d, JCF = 21.9 Hz), 103.0, 21.2 (CH3); DART MS m/z
4-(3-(4-Fluorophenyl)-4-{[2-(4-phenyl-1,3-thiazol-2-
yl)hydrazono]-methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5d
533.1402 [M?H]?, C26H21FN6O2S2H? calcd. 533.1224.
4-(3-(4-Chlorophenyl)-4-{[2-(4-phenyl-1,3-thiazol-2-
yl)hydrazono]-methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5g
M.p. 235–236°C, yield 71%; IR (KBr) cm-1: 3456, 3354
and 3263 (N–H stretch), 1597 (C=N stretch), 1551 (C=N
stretch), 1504 (N–H bend), 1335 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.05 (s, ex, 1H, NH),
9.02 (s, 1H, CH=N), 8.21 (s, 1H, pyrazole–H), 8.17 (d, 2H,
J = 8.7 Hz, Ar), 7.99 (d, 2H, J = 8.7 Hz, Ar), 7.84–7.86
(m, 4H, Ar), 7.50 (s, ex, 2H, SO2NH2), 7.38–7.40 (m, 5H,
Ar), 7.30 (s, 1H, thiazole–H); 13C NMR (75.5 MHz,
M.p. 208–209°C, yield 81%; IR (KBr) cm-1: 3448, 3379
and 3256 (N–H stretch), 1595 (C=N stretch), 1556 (C=N
stretch), 1504 (N–H bend), 1335 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.02 (s, ex, 1H, NH),
9.00 (s, 1H, CH=N), 8.19 (s, 1H, pyrazole–H), 8.16 (d, 2H,
J = 8.7 Hz, Ar), 7.98 (d, 2H, J = 8.7 Hz, Ar), 7.87 (d, 2H,
J = 8.4 Hz, Ar), 7.84 (d, 2H, J = 8.4 Hz, Ar), 7.59 (d, 2H,
J = 8.4 Hz, Ar), 7.48 (s, ex, 2H, SO2NH2), 7.39 (t, 2H,
J = 8.1 Hz, Ar), 7.29–7.31 (m, 2H, thiazole–H, Ar); 13C
NMR (75.5 MHz, DMSO-d6): d 168.3, 150.9, 150.6, 142.4,
141.4, 135.1, 134.5, 133.9, 131.3, 130.7, 129.3, 129.0,
127.9, 127.8, 125.9, 119.1, 118.2, 103.9.; DART MS m/z
535.0794 [M?H]?, C25H19ClN6O2S2H? calcd. 535.0772.
1
DMSO-d6): d 168.3, 162.8 (d, JCF = 246.1 Hz), 150.9,
142.4, 141.4, 135.1, 134.6, 131.2 (d, JCF = 8.3 Hz),
3
129.0, 127.9, 127.8, 125.9, 119.0, 118.1, 115.9 (d,
2JCF = 21.1 Hz), 103.9; DART MS m/z 519.1096
[M?H]?, C25H19FN6O2S2H? calcd. 519.1068.
4-(4-{[2-(4-(4-Chlorophenyl)-1,3-thiazol-2-yl)-
hydrazono]methyl-3-(4-fluorophenyl)}-1H-pyrazol-1-
yl)benzenesulfonamide 5e
4-(3-(4-Chlorophenyl)-4-{[2-(4-(4-chlorophenyl)-1,3-
thiazol-2-yl)-hydrazono]methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5h
M.p. 230–231°C, yield 79%; IR (KBr) cm-1: 3265, 3144
and 3054 (N–H stretch), 1595 (C=N stretch), 1553 (C=N
stretch), 1512 (N–H bend), 1335 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.02 (s, ex, 1H, NH),
9.01 (s, 1H, CH), 8.19 (s, 1H, CH), 8.16 (d, 2H, J = 8.7 Hz,
Ar), 7.98 (d, 2H, J = 8.7 Hz, Ar), 7.84–7.86 (m, 4H, Ar),
7.52 (d, 2H, J = 8.7 Hz, Ar), 7.48 (s, ex, 2H, SO2NH2), 7.36
(m, 3H, thiazole–H, Ar); 13C NMR (75.5 MHz, DMSO-d6):
M.p. 216–218°C, yield 82%; IR (KBr) cm-1: 3258, 3152
and 3061 (N–H stretch), 1595 (C=N stretch), 1551 (C=N
stretch), 1504 (N–H bend), 1337 and1156 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.03 (s, ex, 1H, NH),
9.00 (s, 1H, CH=N), 8.22 (s, 1H, pyrazole–H), 8.16 (d, 2H,
J = 8.4 Hz, Ar), 7.99 (d, 2H, J = 8.4 Hz, Ar), 7.85-7.87
(m, 4H, Ar), 7.59 (d, 2H, J = 8.4 Hz, Ar), 7.43–7.48 (m,
4H, SO2NH2, Ar), 7.35 (s, 1H, thiazole–H); 13C NMR
(75.5 MHz, DMSO-d6): d 168.4, 150.6, 149.7, 142.4,
141.4, 134.7, 133.9, 132.3, 131.3, 130.7, 129.3, 129.0,
127.8, 127.6, 119.1, 118.2, 104.7; DART MS m/z 569.0365
[M?H]?, C25H18Cl2N6O2S2H? calcd. 569.0382.
1
d 168.5, 162.8 (d, JCF = 246.8 Hz), 150.9, 149.6, 142.4,
141.4, 134.7, 134.0, 132.3, 131.2 (d, 3JCF = 8.3 Hz), 129.0,
2
127.8, 127.6, 119.0, 118.0, 115.9 (d, JCF = 21.8 Hz),
104.7; DART MS m/z 553.0702 [M?H]?, C25H18ClFN6
O2S2H? calcd. 553.0678.
4-(3-(4-Fluorophenyl)-4-{[2-(4-(4-methylphenyl)-1,3-
thiazol-2-yl)-hydrazono]methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5f
4-(3-(4-Chlorophenyl)-4-{[2-(4-(4-methylphenyl)-1,3-
thiazol-2-yl)-hydrazono]methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5i
M.p. 233–235°C, yield 83%; IR (KBr) cm-1: 3253, 3154
and 3063 (N–H stretch), 1595 (C=N stretch), 1553 (C=N
stretch), 1504 (N–H bend), 1331 and 1157 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6); d 12.05 (s, ex, 1H, NH),
9.02 (s, 1H, CH=N), 8.20 (s, 1H, Pyrazole–H), 8.15 (d, 2H,
J = 8.7 Hz, Ar), 7.97 (d, 2H, J = 8.7 Hz, Ar), 7.85 (dd,
M.p. 226–228°C, yield 81%; IR (KBr) cm-1: 3258, 3153
and 3044 (N–H stretch), 1597 (C=N stretch), 1553 (C=N
stretch), 1509 (N–H bend) 1339 and1148 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.03 (s, ex, 1H, NH),
9.01 (s, 1H, CH=N), 8.20 (s, 1H, pyrazole–H), 8.16 (d, 2H,
J = 8.4 Hz, Ar), 7.99 (d, 2H, J = 8.4 Hz, Ar), 7.87 (d, 2H,
J = 8.4 Hz, Ar), 7.72 (d, 2H, J = 8.4 Hz, Ar), 7.58 (d, 2H,
J = 8.4 Hz, Ar), 7.51 (s, ex, 2H, SO2NH2), 7.17–7.20 (m,
3H, thiazole–H, Ar), 2.30 (s, 3H, CH3); 13C NMR
3
4
2H, JHH = 8.4 Hz, JHF = 5.4 Hz, Ar), 7.72 (d, 2H,
J = 8.4 Hz, Ar), 7.34 (t, 2H, J = 8.4 Hz, Ar), 7.47 (s, ex,
2H, SO2NH2), 7.19–7.22 (m, 3H, thiazole–H, Ar), 2.31 (s,
3H,CH3); 13C NMR (75.5 MHz, DMSO-d6): d 168.2, 162.6
123

Med Chem Res
(75.5 MHz, DMSO-d6): d 168.2, 150.9, 150.6, 142.4,
141.4, 137.2, 134.4, 133.9, 132.4, 131.3, 130.7, 129.6,
129.2, 129.0, 127.8, 125.9, 119.1, 118.2, 103.0, 21.2 (CH3);
DART MS m/z 549.0946 [M?H]?, C26H21ClN6O2S2H?
calcd. 549.0929.
7.35 (d, 2H, J = 8.4 Hz, Ar), 7.19–7.21 (d, 3H, thiazole–
H, Ar), 2.39 (s, 3H, CH3), 2.31 (s, 3H, CH3); 13C NMR
(75.5 MHz, DMSO-d6): d 168.2, 152.0, 150.9, 142.3,
141.5, 138.6, 137.2, 134.8, 129.67, 129.62, 129.5, 128.8,
128.2, 127.9, 125.9, 119.0, 118.1, 103.0, 21.3 (CH3), 21.2
(CH3);
DART
MS
m/z
529.1441
[M?H]?,
4-(3-(4-Methylphenyl)-4-{[2-(4-phenyl-1,3-thiazol-2-
yl)hydrazono]-methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5j
C27H25N6O2S2H? calcd. 529.1475.
4-(3-(4-Methoxyphenyl)-4-{[2-(4-phenyl-1,3-thiazol-2-
yl)hydrazono]-methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5m
M.p. 220–221°C, yield 82%; IR (KBr) cm-1: 3256, 3153
and 3064 (N–H stretch), 1504 (N–H bend), 1327 and1157
1
(s, SO2 stretch); H NMR (300 MHz, DMSO-d6): d 12.05
M.p. 233–234°C, yield 84%; IR (KBr) cm-1: 3263, 3154 and
3063 (N–H stretch), 1574 (C=N stretch), 1512 (N–H bend),
1333 and 1157 (s, SO2 stretch); 1H NMR (300 MHz, DMSO-
d6): d 12.03 (s, ex, 1H, NH), 8.98 (s, 1H, CH=N), 8.22 (s, 1H,
pyrazole–H), 8.18 (d, 2H, J = 8.4 Hz, Ar), 7.99 (d, 2H,
J = 8.4 Hz, Ar), 7.86 (d, 2H, J = 8.4 Hz, Ar), 7.75 (d, 2H,
J = 8.4 Hz, Ar), 7.49 (s, ex, 2H, SO2NH2), 7.40 (t, 2H,
J = 8.4 Hz, Ar), 7.29–7.31 (m, 2H, thiazole–H, Ar), 7.09 (d,
2H, J = 8.4 Hz, Ar), 3.84 (s, 3H, OCH3); 13C NMR
(75.5 MHz, DMSO-d6): d 168.4,160.1, 151.9, 150.9, 142.2,
141.5, 135.1, 134.9, 130.3, 129.0, 128.3, 127.9, 127.7, 125.9,
124.7, 119.0, 117.9, 114.5, 103.9, 55.7 (OCH3); DART MS
m/z 531.1287 [M?H]?, C26H22N6O2S2H? calcd. 531.1268.
(bs, ex, 1H, NH), 8.99 (s, 1H, CH=N), 8.22 (s, 1H, pyra-
zole–H), 8.19 (d, 2H, J = 8.7 Hz, Ar), 7.99 (d, 2H,
J = 8.7 Hz, Ar), 7.86 (d, 2H, J = 8.7 Hz, Ar), 7.71 (d, 2H,
J = 8.7 Hz, Ar), 7.49 (s, ex, 2H, SO2NH2), 7.31–7.43 (m,
3H, thiazole–H, Ar), 2.39 (s, 3H, CH3); 13C NMR
(75.5 MHz, DMSO-d6): d 168.3, 152.1, 150.8, 142.3,
141.5, 138.6, 135.1, 134.9, 129.6, 129.5, 129.0, 128.8,
128.2, 127.9, 127.8, 126.0, 119.0, 118.1, 103.9, 21.4 (CH3);
DART MS m/z 515.1336 [M?H]?, C26H22N6O2S2H?
calcd. 515.1318.
4-(4-{[2-(4-(4-Chlorophenyl)-1,3-thiazol-2-
yl)hydrazono]methyl}-3-(4-methylphenyl)-1H-pyrazol-1-
yl)benzenesulfonamide 5k
4-(4-{[2-(4-(4-Chlorophenyl)-1,3-thiazol-2-yl)-
hydrazono]methyl}-3-(4-methoxy-phenyl)-1H-pyrazol-1-
yl)benzenesulfonamide 5n
M.p. 230–232°C, yield 73%; IR (KBr) cm-1: 3256, 3152
and 3061 (N–H stretch), 1597 (C=N stretch), 1556 (C=N
stretch), 1503 (N–H bend) 1341 and 1153 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.03 (s, ex, 1H, NH),
8.99 (s, 1H, CH=N), 8.21 (s, 1H, pyrazole–H), 8.17 (d, 2H,
J = 8.4 Hz, Ar), 7.98 (d, 2H, J = 8.4 Hz, Ar), 7.86 (d, 2H,
J = 8.4 Hz, Ar), 7.69 (d, 2H, J = 8.4 Hz, Ar), 7.44–7.47
(m, 4H, SO2NH2, Ar), 7.33-7.37 (m, 3H, thiazole–H, Ar),
2.40 (s, 3H, CH3); 13C NMR (75.5 MHz, DMSO-d6): d
168.1, 150.9, 150.6, 142.3, 141.2, 136.9, 134.2, 134.1,
132.1, 131.3, 130.8, 129.6, 129.1, 129.0, 127.6, 125.9,
119.1, 118.2, 103.2, 21.4 (CH3); DART MS m/z 549.0954
[M?H]?, C26H21ClN6O2S2H? calcd. 549.0929.
M.p. 168–170°C, yield 74%; IR (KBr) cm-1: 3243, 3134
and 3061 (N–H stretch), 1597 (C=N stretch), 1551 (C=N
stretch), 1504 (N–H bend), 1337 and 1154 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.02 (s, ex, 1H, NH),
8.98 (s, 1H, CH=N), 8.30 (s, 1H, pyrazole–H), 8.17 (d, 2H,
J = 8.4 Hz, Ar), 7.97 (d, 2H, J = 8.4 Hz, Ar), 7.86 (d, 2H,
J = 8.4 Hz, Ar), 7.67 (d, 2H, J = 8.4 Hz, Ar), 7.44–7.47
(m, 4H, SO2NH2, Ar), 7.38 (s, 1H, thiazole–H), 7.09 (d,
2H, J = 8.4 Hz, Ar), 3.84 (s, 3H, OCH3); 13C NMR
(75.5 MHz, DMSO-d6): d 168.5, 160.1, 151.9, 149.6,
142.2, 141.5, 135.1, 134.0, 132.3, 130.3, 129.0, 128.3,
127.7, 127.6, 124.7, 119.0, 117.9, 114.5, 104.7, 55.7
(OCH3); DART MS m/z 565.0906 [M?H]?,
C25H19ClN6O2S2H? calcd. 565.0878.
4-(3-(4-Methylphenyl)-4-{[2-(4-(4-methylphenyl)-1,3-
thiazol-2-yl)-hydrazono]methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5l
4-(3-(4-Methoxyphenyl)-4-{[2-(4-(4-methylphenyl)-1,3-
thiazol-2-yl)-hydrazono]-methyl}-1H-pyrazol-1-
yl)benzenesulfonamide 5o
M.p. 197–198°C, yield 78%; IR (KBr) cm-1: 3263, 3152
and 3053 (N–H stretch), 1566 (C=N stretch), 1504 (N–H
bend), 1335 and 1149 (s, SO2 stretch); 1H NMR (300 MHz,
DMSO-d6): d 12.03 (s, ex, 1H, NH), 8.97 (s, 1H, CH=N),
8.21 (s, 1H, pyrazole–H), 8.17 (d, 2H, J = 8.7 Hz, Ar),
7.98 (d, 2H, J = 8.7 Hz, Ar), 7.73 (d, 2H, J = 8.4 Hz, Ar),
7.70 (d, 2H, J = 8.4 Hz, Ar), 7.46 (s, ex, 2H, SO2NH2),
M.p. 170–171°C, yield 80%; IR (KBr) cm-1: 3261, 3153
and 3033 (N–H stretch), 1596 (C=N stretch), 1553 (C=N
stretch), 1511 (N–H bend), 1333 and 1156 (s, SO2 stretch);
1H NMR (300 MHz, DMSO-d6): d 12.03 (s, ex, 1H, NH),
123

Med Chem Res
8.96 (s, 1H, CH=N), 8.28 (s, 1H, pyrazole–H), 8.18 (d, 2H,
J = 8.4 Hz, Ar), 7.99 (d, 2H, J = 8.4 Hz, Ar), 7.83 (d, 2H,
J = 8.4 Hz, Ar), 7.66 (d, 2H, J = 8.4 Hz, Ar), 7.47 (s, ex,
2H, SO2NH2), 7.38 (d, 2H, J = 8.4 Hz, Ar), 7.26 (s, 1H,
thiazole–H), 7.08 (d, 2H, J = 8.4 Hz, Ar), 3.79 (s, 3H,
OCH3), 2.31 (s, 3H, CH3); 13C NMR (75.5 MHz, DMSO-
d6): d 168.2, 160.5, 153.8, 142.9, 142.1, 141.5, 134.2,
132.4, 130.1, 129.2, 128.4, 127.8, 127.6, 123.9, 119.0,
117.1, 114.5, 104.4, 55.7 (OCH3), 21.8 (CH3); DART MS
m/z 545.1456 [M?H]?, C27H25ClN6O3S2H? calcd.
545.1424.
(Ahmad and Beg, 2001) All the microbial cultures were
adjusted to 0.5 McFarland standards, which are visually
comparable to a microbial suspension of *1.5 9 108 cfu/
ml (McFaraland, 1907). 20 ml of Mueller–Hinton agar
media was poured into each Petri plate, and plates were
swabbed with 100 ll inocula of the test microorganisms,
and kept for 15 min for adsorption. Using sterile cork borer
of 8 mm diameter, wells were bored into the seeded agar
plates, and these were loaded with a 100 ll volume with
concentration of 4 mg/ml of each compound reconstituted
in the dimethylsulfoxide (DMSO). All the plates were
incubated at 37°C for 24 h. Antibacterial activity of twenty
synthetic compounds was evaluated by measuring the zone
of growth inhibition against the test organisms with zone
reader (HiAntibiotic zone scale). DMSO was used as a
negative control whereas ciprofloxacin was used as a
positive control. The experiments were performed in trip-
licates. The antibacterial activity of the compounds was
compared with ciprofloxacin as standard. Minimum
inhibitory concentration (MIC) of the newly synthesized
compounds against tested bacteria was determined using
macrodilution tube method as recommended by NCCLS
(2000).
Pharmacological assay
Carrageenan-induced rat paw edema assay
Male Wistar albino rats weighing 200–250 g were used
throughout the study. They were kept in the animal house
under standard conditions of light and temperature with free
access to food and water. Food was withdrawn 12 h before
and during experimental hours. The animals were randomly
divided into groups each consisting of six rats. One group of
six rats was kept as control and received tween 80 (95:5).
Another group received the standard drug indomethacin at a
dose of 10 mg/kg body weight ip. Other groups of rats were
administered the test compounds at a dose of 50 mg/kg
body weight orally. A mark was made on the left hind paw
just beyond the tibiotarsal articulation, so that, every time
the paw was dipped up to the fixed mark, a constant paw
volume was ensured. Paw volumes were measured using a
plethysmometer (model 7140, Ugo Basile, Italy). Thirty
minutes after administration of test compounds and stan-
dard drug, 0.1 ml of 1% w/v of carrageenan suspension in
normal saline was injected into subplanter region of the left
hind paw of all the animals. The initial paw volume was
measured within 30 s of the injection and remeasured again
1, 2, 3, and 4 h after administration of carrageenan. The
edema was expressed as an increase in the volume of paw,
and the percentage of edema inhibition for each rat and each
group was obtained as follows:
Acknowledgments The authors (P. K. and N. C.) are grateful to the
Council of Scientific and Industrial Research (CSIR), New Delhi for
the awards of junior and senior research fellowships, respectively.
The authors are thankful to the Sophisticated Analytical Instrument
Facility, Central Drug Research Institute, Lucknow for the Mass
spectra facilities.
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