Synthesis and anti-inflammatory activity of some pyrazole derivatives

Article abstract of DOI:10.1007/s00044-011-9691-4

A novel series of pyrazoles containing benzenesulfonamides, 1,3,4-oxadiazole-2-thiones, 4-substituted-1,2,4-triazole-3-thiones, and 2-substituted-1,3,4-thiadiazoles has been synthesized. Anti-inflammatory activity of some synthesized compounds was evaluated in vivo utilizing a standard acute carrageenan-induced paw edema method. The most active anti-inflammatory agents 3, 8f, and 10f were evaluated for ulcerogenic liability in rats compared to indomethacin and celecoxib as reference standards. Molecular modeling studies were initiated herein to validate the attained pharmacological data and provide understandable evidence for the observed anti-inflammatory behavior.

Full text of DOI:10.1007/s00044-011-9691-4

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2012) 21:1722–1733
DOI 10.1007/s00044-011-9691-4
ORIGINAL RESEARCH
Synthesis and anti-inflammatory activity of some pyrazole
derivatives
•
Samir M. El-Moghazy Flora F. Barsoum
•
•
Hamdy M. Abdel-Rahman Adel A. Marzouk
Received: 31 December 2010 / Accepted: 1 June 2011 / Published online: 11 June 2011
Ó Springer Science+Business Media, LLC 2011
Abstract A novel series of pyrazoles containing ben-
zenesulfonamides, 1,3,4-oxadiazole-2-thiones, 4-substituted-
1,2,4-triazole-3-thiones, and 2-substituted-1,3,4-thiadiazoles
has been synthesized. Anti-inflammatory activity of some
synthesized compounds was evaluated in vivo utilizing a
standard acute carrageenan-induced paw edema method. The
most active anti-inflammatory agents 3, 8f, and 10f were
evaluated for ulcerogenic liability in rats compared to indo-
methacin and celecoxib as reference standards. Molecular
modeling studies were initiated herein to validate the attained
pharmacological data and provide understandable evidence
for the observed anti-inflammatory behavior.
Introduction
Non-steroidal anti-inflammatory drugs (NSAIDs) are
commonly used for the treatment of pain and inflammation
(Amin et al., 2009) by counteracting the cyclooxygenase
enzymes (COX). However, long-term therapy may cause
gastrointestinal complications ranging from stomach irri-
tation to life-threatening gastrointestinal ulceration and
bleeding (Wolfe et al., 1999). Therefore, it is important to
find new anti-inflammatory drugs with a potential for
clinical use and not associated with adverse effects. Pyra-
zole derivatives represent an important class of heterocy-
cles due to their highly pronounced biological and
pharmacological activities. Several pyrazole compounds
have been reported to be potential therapeutic agents for
the treatment of inflammation (Ranatunge et al., 2004;
Keywords Anti-inflammatory activity ꢀ COX-2 ꢀ
Pyrazole ꢀ Synthesis ꢀ Oxadiazoles ꢀ 1,2,4-Triazoles
´
Szabo et al., 2008; Bekhit and Abdel-Aziem, 2004; Bekhit
et al., 2006) including the marketed selective COX-2 drug,
celecoxib (Fig. 1) that have been shown to be well toler-
ated with reduced gastrointestinal side effects (Sakya et al.,
2008). Moreover, various substituted pyrazoles were
reported to possess antitumor properties (Rostom et al.,
2003; Lin et al., 2007), others were used for treating Alz-
Electronic supplementary material The online version of this
article (doi:10.1007/s00044-011-9691-4) contains supplementary
material, which is available to authorized users.
¨
heimer’s disease (Gokhan-Kelekc¸i et al., 2007) and
acquired immunodeficiency syndrome (AIDS) (Shen et al.,
2004).
S. M. El-Moghazy ꢀ F. F. Barsoum
Motivated by the aforementioned findings and as a
continuation of our on-going program in the field of anti-
inflammatory agents (Bekhit et al., 2006; Barsoum et al.,
2006), we intended to investigate the synthesis of new
pyrazoles bridged to other anti-inflammatory nuclei as
1,3,4-oxadiazoles, 1,2,4-triazoles, and 1,3,4-thiadiazoles
(Abdel-Rahman and Hussien, 2006; Amir and Kumar,
2005) to develop new anti-inflammatory drugs with greater
activity and less side effects.
Faculty of Pharmacy, Pharmaceutical Chemistry Department,
Cairo University, Cairo, Egypt
H. M. Abdel-Rahman (&)
Faculty of Pharmacy, Medicinal Chemistry Department,
Assiut University, Assiut 71526, Egypt
e-mail: hamdym01@yahoo.com
A. A. Marzouk
Faculty of Pharmacy, Pharmaceutical Chemistry Department,
Al-Azhar University, Assiut branch, Assiut, Egypt
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Med Chem Res (2012) 21:1722–1733
1723
1H-pyrazol-1-yl)acetyl]-4-substituted thiosemicarbazides
8a–r (Scheme 3). The structures of 8a–r were established
1
through spectroscopic (IR, H-NMR, and MS) as well as
1
elemental analyses data. H-NMR spectra exhibited three
singlet signals at d = 7.4–11.3 region assignable for the
amidic protons (disappeared upon deuteration), and the
mass spectra exhibited the parent molecular ion peaks
confirming the assumed structures. On the other hand,
refluxing 8 with sodium hydroxide in ethanol afforded the
1,2,4-triazole-3-thiones derivatives 9, while stirring 8 with
sulfuric acid yielded the 1,3,4-thiadiazole derivatives 10
through intramolecular cyclization onto the carbonyl
group (Scheme 3). The IR spectra of 9 and 10 derivatives
reveal the absence of a band assignable for the carbonyl
group at 1741–1674 cm-1 region confirming the cyclized
structures. The 1H-NMR spectra of 9 and 10 strongly
support the presumed cyclized structures, exhibiting only
one D2O exchangeable amino signal at d = 7.2–15.2 and
at 7.8–11.8 ppm for 9 and 10, respectively, and the mass
spectra exclude any other possible structure, revealing the
expected molecular ion peaks.
Fig. 1 Structures of the selective COX-2 inhibitors, celecoxib and
SC-558
Results and discussion
Chemistry
Reaction of b-diketone 1c with 4-hydrazino-N-(substi-
tuted)benzenesulfonamide hydrochlorides in absolute eth-
anol containing sodium acetate and glacial acetic acid,
afforded directly 4-[5-(4-chlorophenyl)-3-methyl-1H-pyr-
azol-1-yl]-N-(substituted) benzenesulfonamides 3 and 4.
The IR spectra of the products revealed the absence of
a band assignable for the two carbonyl groups, while the
1H-NMR spectra exhibited the pyrazole proton (H-4) as a
sharp singlet signal at d = 7.0–7.2 ppm. In addition, the
mass spectra exhibited the parent molecular ion peaks
confirming the assumed structures.
Anti-inflammatory activity
The anti-inflammatory activity of 13 representative com-
pounds was determined in vivo by the acute carrageenan-
induced paw edema standard method in rats (Winter et al.,
1962). From the obtained results (Table 1), it has been
observed that several newly prepared compounds (3, 4, 8f,
and 10r) revealed better anti-inflammatory properties
(61.12–62.67% inhibition of edema) comparable to that of
indomethacin (60.8% inhibition of edema). In addition,
compound 10f seems to be the most effective prepared
anti-inflammatory agent, revealed better activity (64.93%
inhibition of edema) than both indomethacin and celecoxib
(reference standards).
On the other hand, reaction of 1a–c with ethylhydrazino
acetate hydrochloride followed by refluxing with hydrazine
hydrate afforded the acid hydrazide derivatives 6a–c in
good yields (Scheme 2). The IR spectrum of 6c revealed
strong sharp bands at m = 3291, 3209 cm-1 region attrib-
uted to the amino and amidic bands and a strong carbonyl
stretching vibration band at m = 1665 cm-1 1H-NMR
.
spectrum of 6c exhibited the aminic and amidic protons as
singlet signals at d = 4.3 and 9.3 ppm, respectively (deu-
terium exchangeable). Moreover, refluxing 6a–c with CS2/
KOH in ethanol yielded exclusively the 5-(3-methyl-5-
substituted-1H-pyrazol-1-ylmethyl)-3H-1,3,4-oxadiazole-
2-thiones 7a–c in good yields and their structures were
confirmed on the basis of their elemental and spectral data
(Scheme 2). The IR spectra of the products revealed a
strong band at m = 3446–3422 cm-1 region attributed for
one amino group and the absence of a band assignable for
the carbonyl group at 1665 cm-1 region confirming the
However, comparing the activity of 1,3,4-oxadiazole-2-
thione compounds 7a–c, it was observed that replacing the
alkyl group by aromatic moiety at position 5, increased
slightly the anti-inflammatory activity. In addition, com-
paring the activity of thiosemicarbazide compounds 8d, 8e,
and 8f, it has been noticed that substitution of the phenyl
group with an electron-withdrawing group (NO2) 8f
(62.67% inhibition of edema), seems more favorable for
constructing an anti-inflammatory active agent than the
case of substitution with an electron-donating groups (CH3,
OCH3) as exhibited in 8d and 8e (40.83 and 46.41%
inhibition of edema, respectively). Meanwhile, upon
cyclization of the highly potent thiosemicarbazide 8f using
sulfuric acid, the obtained 1,3,4-thiadiazole 10f (64.93%
inhibition of edema) showed a significant increase in the
anti-inflammatory activity, while remarkable decrease in
the potency was observed upon cyclization of 8f using
1
cyclized form structure. In addition, H-NMR spectra dis-
played only one D2O exchangeable NH proton as singlet
signal at d = 7.5–7.9 ppm and the mass spectra exhibited
the parent molecular ion peaks confirming also the cyclized
structure.
Meanwhile, reaction of 6a–c with isothiocyanates in
refluxing ethanol gave directly 2-[2-(3-methyl-5-substituted-
123

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Med Chem Res (2012) 21:1722–1733
Table 1 Anti-inflammatory activity of the tested compounds using
carrageenan-induced paw edema in rats
Table 3 The final docking score (S) for the first poses of compound 3
in the active site of COX-2
Compound
Percentage inhibition of edema SE
1 h 2 h 3 h
0.00 0.00 0.00
Pose number
The final score (S)
(kcal/mol)
1
-10.3836
-10.2233
-9.8776
Control
2
Indomethacin 31.51 2.320
40.13 2.911
60.81 3.152
3
Celecoxib
31.43 2.871
45.75 3.410
63.78 3.301
Average
-10.1615
3
37.21 1.874b 49.81 1.192b 62.47 1.156b
34.11 1.449b 44.32 3.273b 62.03 1.970b
14.38 3.095b 21.53 3.707b 34.88 2.693b
26.31 3.031b 34.17 2.708b 48.71 2.261b
15.44 3.028b 31.22 3.233b 39.18 2.540b
12.27 3.572a 22.90 4.099a 40.83 3.218a
30.33 2.957b 41.38 3.471b 46.41 3.704b
36.13 2.191b 44.43 2.396b 62.67 1.179b
13.15 2.591a 22.73 4.901a 33.42 2.955a
16.61 2.925b 27.15 2.927b 36.38 2.313b
37.52 1.031b 49.96 2.272b 64.93 2.222b
26.86 1.556b 42.25 1.327b 54.11 1.255b
32.79 1.477b 45.01 1.026b 61.12 0.921b
4
7a
7b
7c
8d
8e
8f
Molecular modeling studies
Molecular modeling study of a highly observed anti-
inflammatory active agent 3 was initiated herein to under-
stand the observed pharmacological data. Docking studies
were performed by Molecular Operating Environment
(MOE, Version 2008, Chemical Computing Group Inc.,
Montreal, Quebec, Canada), exhibiting COX-2 enzyme co-
crystallized with SC-558 (PDB ID: 1CX2), which used as a
template in this study (Kurumbail et al., 1996). 100 Docking
interactions for each ligand were performed and the top score
docking energy value was recorded (Table 3).
9d
9f
10f
10h
10r
All values are represented as means of 6 experiments SE. Statis-
tical analysis was carried out by one-way ANOVA test followed by
Dunnett’s t test at P \ 0.05 and 0.01
Docking compound 3 in the active site of COX-2
(Fig. 2) using the same mentioned procedure, exhibit two
distinguished interactions with two different amino acids
which are very similar interactions as in the case of
SC-588. The first observed one is due to interaction of one
of the sulfamoyl oxygen of 3 with His90 amino function.
The other observed one is due to Phe518 amino function
interaction with the other sulfamoyl oxygen of 3.
a
Significant difference from the control value at P \ 0.05
b
Significant difference from the control value at P \ 0.01
sodium hydroxide to obtain the 1,2,4-triazole 9f (36.38%
inhibition of edema).
Ulcerogenic liability
Ulcerogenic liability of the most promising prepared anti-
inflammatory active agents (3, 8f, and 10f) was determined
following the previously reported standard method (Bar-
soum et al., 2006, 2009) using indomethacin as a reference
standard. From the obtained data (Table 2) it has been
noticed that all compounds reveal lower ulcer indexes
(5.2–18.6) and they are considered more safer than indo-
methacin itself which reveals ulcer index 20.4.
Experimental
Melting points were uncorrected and were carried out by
the open capillary tube method using an Electrothermal
9100 digital melting point apparatus (Stuart Scientific,
Model SMM, UK). TLC was carried out using silica gel 60
F254 precoated sheets (E. Merck, Darmstadt, Germany) and
was visualized using UV lamp (Spectroline Model CM 10,
USA). IR spectra were recorded (KBr disks) on Shimadzu
IR 400-91527 spectrophotometer (Shimadzu, Japan).
1H-NMR spectra were recorded on a Varian EM-360L
(60 MHz) and Varian GEMINI 200 (200 MHz) spec-
trometers (Varian, USA). Chemical shifts were expressed
in d units with tetramethylsilane as the internal standard.
EI-mass spectra were recorded on JEOL, JMS-600H, mass
spectrometer (JEOL, Japan), at 70 eV. Elemental analyses
were performed at the Microanalytical Center, Faculty of
Science, Cairo University and Assiut University.
Table 2 Ulcerogenic liability of the highly active anti-inflammatory
compounds
Compound
Number of animals
with ulcer
Average
severity
Ulcer
index
Control
0/5
5/5
2/5
5/5
4/5
0.0
2.8
0.4
2.6
1.8
0.0
Indomethacin
20.4
5.2
3
8f
10f
18.6
15.6
The starting compounds 1b, c (Furniss et al., 1989), 2a,
b (Aoki, 1955), 4, 5a, b, 6a, b (Ahmad et al., 1996), 5c
123

Med Chem Res (2012) 21:1722–1733
1725
Fig. 2 Schematic
representation of a docking pose
of 3 in the active site of COX-2
(obtained using MOE software)
(Stanovnik and Svete, 2002) were prepared following the
reported literature methods. Compound 1a was purchased
from El-Nasr Chemical Company Egypt.
100), 266 (39), 232 (28), 76 (41). Anal. (C16H14ClN3O2S), C,
H, N.
4-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-yl]-
N-(2-thiazolyl)benzenesulfonamide (4)
General method for the preparation of 4-[5-(4-
chlorophenyl)-3-methyl-1H-pyrazol-1-yl]-
N-(substituted)benzenesulfonamides 3,4
Yield 75%, m.p. 239–240°C. IR: mmax/cm-1 3430 (NH),
1
1594 (C=N), 1575, 1365. H-NMR (DMSO-d6): d 2.5 (s,
A mixture of equimolar amount of the appropriate 1c,
4-hydrazino-N-(substituted)benzenesulfonamide hydrochlo-
ride, sodium acetate, and glacial acetic acid (5 mmol each)
in ethanol (250 ml) was stirred for 24 h at room tempera-
ture. Filtration of the mixture followed by concentrating
the filtrate yielded a solid product that was collected, dried,
and crystallized from ethanol (Scheme 1).
H, CH3), 7.2 (s, 1H, pyrazole H-4), 7.4–9.2 (m, 11H, arom.
H ? NH). MS: m/z (%) = 432 (M?2, 11), 430 (M?, 29),
331 (5), 240 (6), 266 (100), 190 (15), 76 (15). Anal.
(C19H15ClN4O2S2), C, H, N.
Synthesis of 2-[5-(4-chlorophenyl)-3-methyl-1H-pyrazol-1-
yl] acetic acid hydrazide (6c)
4-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-
yl]benzenesulfonamide (3)
To a solution of 5c (5 mmol) in ethanol, hydrazine hydrate
100% (5 mmol) was added dropwise with continuous stir-
ring. The reaction mixture was then refluxed for 3 h and
allowed to attain room temperature. The separated solid was
filtered, dried, and crystallized from ethanol (Scheme 2).
Yield 85%, m.p. 196–197°C. IR: mmax/cm-1 3291, 3209
(NH), 1665 (C=O), 1629, 1539. 1H-NMR (DMSO-d6): d 2.2
Yield 80%, m.p. 225–226°C. IR: mmax/cm-1 3270, 3168
(NH2), 1596 (C=N), 1548, 1345. 1H-NMR (DMSO-d6): d 2.6
(s, 3H, CH3), 7.0 (s, 1H, pyrazole H-4), 7.8–8.8 (m, 10H,
arom. H ? NH2). MS: m/z (%) = 349 (M?2, 31), 347 (M?,
123

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Med Chem Res (2012) 21:1722–1733
Scheme 1 Synthesis of the
pyrazole compounds 3 and 4
Scheme 2 Synthesis of the
pyrazole compounds 5, 6, and 7
(s, 3H, CH3), 4.3 (s, 2H, NH2), 4.6 (s, 2H, CH2), 6.2 (s, 1H,
pyrazole H-4), 7.4–7.8 (m, 4H, arom. H), 9.3 (s, H, NH). MS:
m/z (%) = 266 (M?2, 17), 264 (M?, 32), 205 (100), 192 (18),
75 (36), 68 (8). Anal. (C12H13ClN4O), C, H, N.
CH3), 2.6 (s, 3H, CH3), 5.8 (s, 2H, CH2), 6.5 (s, 1H, pyr-
azole H-4), 7.5 (br.s, H, NH). MS: m/z (%) = 210 (M?,
57), 109 (100), 96 (9), 82 (10), 68 (23). Anal.
(C8H10N4OS), C, H, N.
General method for the preparation of 5-(3-methyl-5-
substituted-1H-pyrazol-1-yl methyl)-3H-1,3,4-
oxadiazole-2-thiones (7)
5-(3-Methyl-5-phenyl-1H-pyrazol-1-ylmethyl)-3H-1,3,4-
oxadiazole-2-thione (7b)
Yield 75%, m.p. 190–192°C. IR: mmax/cm-1 3423 (NH),
1
A mixture equimolar amount of the appropriate 6a–c,
potassium hydroxide (5 mmol each) and carbon disulfide
(5 ml) in ethanol (25 ml) was refluxed for 12 h on a steam
bath. The reaction mixture was concentrated, cooled, and
neutralized with hydrochloric acid solution. The separated
solid was collected, washed with water, dried, and crys-
tallized from ethanol (Scheme 2).
1625, 1537, 1150. H-NMR (CDCl3): d 2.3 (s, 3H, CH3),
5.2 (s, 2H, CH2), 6.2 (s, 1H, pyrazole H-4), 7.2–7.6 (m, 6H,
arom. H ? NH). MS: m/z (%) = 272 (M?, 100), 257 (1),
171(84), 158 (9), 144 (2), 77 (7). Anal. (C13H12N4OS), C,
H, N.
5-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-yl methyl]-
3H-1,3,4-oxadiazole-2-thione (7c)
5-(3,5-Dimethyl-1H-pyrazol-1-ylmethyl)-3H-1,3,4-
oxadiazole-2-thione (7a)
Yield 68%, m.p. 224–225°C. IR: mmax/cm-1 3446 (NH),
1551, 1493 (C=N, C=C), 1151. H-NMR (DMSO-d6): d
2.2 (s, 3H, CH3), 5.4 (s, 2H, CH2), 6.3 (s, 1H, pyrazole
1
Yield 60%, m.p. 213–215°C. IR: mmax/cm-1 3422 (NH),
1629, 1555, 1158. 1H-NMR (DMSO-d6): d 2.4 (s, 3H,
H-4), 7.5–7.8 (m, 4H, arom. H), 7.9 (s, 1H, NH). MS:
123

Med Chem Res (2012) 21:1722–1733
1727
m/z (%) = 308 (M?2, 37), 306 (M?, 100), 205 (84), 192
(10), 178 (2), 170 (21), 128 (7). Anal. (C13H11ClN4OS), C,
H, N.
1-[2-(3,5-Dimethyl-1H-pyrazol-1-yl) acetyl]-4-(3-methyl
phenyl) thiosemicarbazide (8d)
Yield 60%, m.p. 175–176°C. IR: mmax/cm-1 3341, 3297,
3240 (NH), 1704 (C=O), 1610, 1592 (C=N, C=C),
1201.1H-NMR (DMSO-d6): d 2.3 (s, 3H, CH3), 2.5 (s, 3H,
CH3) 2.6 (s, 3H, CH3), 5.2 (s, 2H, CH2), 6.4 (s, 1H, pyr-
azole H-4), 7.5 (s, 1H, NH), 7.8–8.3 (m, 4H, arom. H), 9.1
(br.s, 2H, 2NH). MS: m/z (%) = 317 (M?, 14), 168 (25),
153 (1), 109 (100), 95 (7), 68 (10), 55 (5). Anal.
(C15H19N5OS), C, H, N.
General method for the preparation of 1-[2-(3-methyl-
5-substituted-1H-pyrazol-1-yl) acetyl]-4-substituted
thiosemicarbazides (8a–r)
A mixture of equimolar amount of the appropriate 6a–
c and the corresponding isothiocyanate (5 mmol each) was
boiled under reflux in absolute ethanol (25 ml) for 6 h. The
reaction mixture was filtered while hot, concentrated and
kept overnight in the refrigerator. The separated solid was
collected, washed, dried, and crystallized from ethanol
(Scheme 3).
1-[2-(3,5-Dimethyl-1H-pyrazol-1-yl) acetyl]-4-(4-
methoxyphenyl) thiosemicarbazide (8e)
Yield 76%, m.p. 188–190°C. IR: mmax/cm-1 3538, 3241
(NH), 1694 (C=O), 1609, 1541, 1202 H-NMR (DMSO-
1
1-[2-(3,5-Dimethyl-1H-pyrazol-1-yl) acetyl]-4-ethyl
thiosemicarbazide (8a)
d6): d 2.3 (s, 3H, CH3), 2.6 (s, 3H, CH3) 4.1 (s, 3H, OCH3),
5.2 (s, 2H, CH2), 6.3 (s, 1H, pyrazole H-4) 7.3–8.1 (m, 4H,
arom. H), 10.5 (s, 2H, 2NH), 11.1 (s, 1H, NH). Anal.
(C15H19N5O2S), C, H, N.
Yield 73%, m.p. 193–194°C. IR: mmax/cm-1 3423 (NH),
1
1741 (C=O), 1575, 1558, 1141. H-NMR (DMSO-d6): d
1.3 (t, 3H, CH2CH3), 2.5 (s, 6H, 2CH3), 3.9 (q, 2H,
CH2CH3), 5.2(s, 2H, CH2), 6.5 (s, 1H, pyrazole H-4), 8.4
(s, 1H, NH), 9.7 (s, 1H, NH), 10.6 (s, 1H, NH). MS: m/z
(%) = 255 (M?, 18), 168 (2), 153 (3), 109 (100), 68 (6).
Anal. (C10H17N5OS), C, H, N.
1-[2-(3,5-Dimethyl-1H-pyrazol-1-yl) acetyl]-4-(4-
nitrophenyl) thiosemicarbazide (8f)
Yield 86%, m.p. 222–223°C. IR: mmax/cm-1 3270 (NH),
1702 (C=O), 1650, 1619,1204. 1H-NMR (DMSO-d6): d
2.2 (s, 3H, CH3), 2.4 (s, 3H, CH3), 5.2 (s, 2H, CH2), 6.4
(s, 1H, pyrazole H-4), 7.5–8.4 (m, 4H, arom. H), 10.5 (s,
2H, 2NH), 11.2 (s, 1H, NH). Anal. (C14H16N6O3S), C,
H, N.
1-[2-(3,5-Dimethyl-1H-pyrazol-1-yl) acetyl]-4-propyl
thiosemicarbazide(8b)
Yield 68%, m.p. 193–195°C. IR: mmax/cm-1 3243, 3166
(NH), 1694 (C=O), 1620, 1542, 1154. H-NMR (DMSO-
1
d6): d 0.8 (t, 3H, CH2CH2CH3), 1.5–1.7 (sextet, 2H,
CH2CH2CH3), 2.4 (s, 3H, CH3), 2.5 (s, 3H, CH3), 3.4 (q,
2H, CH2 CH2CH3), 4.7 (s, 2H, CH2), 5.8 (s, 1H, pyrazole
H-4), 8.0 (s, 1H, NH), 9.2 (s, 1H, NH), 10.0 (s, 1H, NH).
MS: m/z (%) = 269 (M?, 26), 154 (9), 109 (100), 95 (10),
83 (3), 68 (6). Anal. (C11H19N5OS), C, H, N.
1-[2-(3-Methyl-5-phenyl-1H-pyrazol-1-yl) acetyl]-4-ethyl
thiosemicarbazide (8g)
Yield 60%, m.p. 171–172°C. IR: mmax/cm-1 3264 (NH),
1688 (C=O), 1548, 1499 (C=N, C=C), 1198.1H-NMR
(DMSO-d6): d 1.3 (t, 3H, CH2CH3), 2.6 (s, 3H, CH3) 3.9
(q, 3H, CH2CH3), 5.3 (s, 2H, CH2), 6.8 (s, 1H, pyrazole H-
4), 8.1–8.8 (m, 5H, arom. H), 10.0 (s, H, NH), 10.3 (br.s,
1H, NH), 11.1(s, 1H, NH). MS: m/z (%) = 317 317 (M?,
20), 230 (10), 171 (100), 157 (5), 144 (4), 77 (11), 68 (2).
Anal. (C15H19N5OS), C, H, N.
1-[2-(3,5-Dimethyl-1H-pyrazol-1-yl) acetyl]-4-cyclohexyl
thiosemicarbazide (8c)
Yield 70%, m.p. 189–190°C. IR: mmax/cm-1 3224 (NH),
1695 (C=O), 1654, 1542 (C=N, C=C), 1196.1H-NMR
(DMSO-d6/D2O): d 1.2–1.7 (m, 11H, Cyclohexy), 2.1 (s,
3H, CH3) 2.2(s, 3H, CH3), 4.7 (s, 2H, CH2), 5.8 (s, 1H,
pyrazole H-4), 7.4(br.s, 1H, NH), 8.1(br.s, 1H, NH), 9.8(s,
1H, NH). MS: m/z (%) = 309 (M?, 20), 168 (6), 153 (3),
109 (100), 95 (5), 83 (14), 68 (10), 55 (44). Anal.
(C14H33N5OS), C, H, N.
1-[2-(3-Methyl-5-phenyl-1H-pyrazol-1-yl) acetyl]-4-propyl
thiosemicarbazide (8h)
Yield 60%, m.p. 171–172°C. IR: mmax/cm-1 3268 (NH),
1687 (C=O), 1550, 1497, 1195 .1H-NMR (DMSO-d6): d
0.9 (t, 3H, CH2CH2CH3), 1.7 (m, 2H, CH2CH2CH3) 2.4 (s,
123

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Med Chem Res (2012) 21:1722–1733
Scheme 3 Synthesis of the
pyrazole compounds 8, 9,
and 10
1-[2-(3-Methyl-5-phenyl-1H-pyrazol-1-yl)acetyl]-4-
cyclohexyl thiosemicarbazide (8i)
3H, CH3) 3.7 (q, 2H, CH2CH2CH3), 5.2 (s, 2H, CH2), 6.7
(s, 1H, pyrazole H-4), 8.4(m, 5H, arom-H), 9.9 (br.s, 2H,
2NH), 10.8 (s, 1H, NH). MS: m/z (%) = 317 (M?, 20), 230
(10), 171 (100), 157 (5), 144 (4), 77 (11), 68 (2). Anal.
(C16H21N5OS), C, H, N.
Yield 78%, m.p. 192–194°C. IR: mmax/cm-1 3281 (NH),
1697 (C=O), 1551, 1496, 1224.1H-NMR (DMSO-d6): d
123

Med Chem Res (2012) 21:1722–1733
1729
1.2–1.8 (m, 11H, cyclohexyl), 2.2 (s, 3H, CH3), 4.7 (s, 2H,
CH2), 6.2 (s, 1H, pyrazole H-4), 7.4 (m, 5H, arom. H), 9.3
(s, 1H, NH), 9.4 (s, 1H, NH), 10.1 (s, 1H, NH). Anal.
(C19H25N5OS), C, H, N.
(M?2, 4), 405 (M?, 14), 306 (6), 264 (53), 205 (100), 193
(13), 68 (5). Anal. (C19H24ClN5OS), C, H, N.
1-{2-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-
yl]acetyl}-4-phenylthiosemicarbazide (8o)
1-[2-(3-Methyl-5-phenyl-1H-pyrazol-1-yl) acetyl]-4-(3-
methylphenyl) thiosemicarbazide (8j)
Yield 76%, m.p. 186–187°C. IR: mmax/cm-1 3359 (NH),
1701 (C=O), 1598, 1540, 1190. H-NMR (DMSO-d6): d
1
Yield 60%, m.p. 157–158°C. IR: mmax/cm-1 3245 (NH),
1684 (C=O), 1593, 1549, 1212 .1H-NMR (DMSO-d6): d
2.4 (s, 3H, CH3), 2.5 (s, 3H, CH3), 5.2 (s, 2H, CH2), 6.7
(s, 1H, pyrazole H-4), 7.5–8.4 (m, 9H, arom. H), 9.4 (br.s,
1H, NH), 9.6 (s, 1H, NH), 10.4 (s, 1H, NH). Anal.
(C20H21N5OS), C, H, N.
2.4 (s, 3H, CH3), 5.2 (s, 2H, CH2), 6.7 (s, 1H, pyrazole H-
4), 7.8–8.6 (m, 9H, arom. H), 10.4 (s, 2H, 2NH), 11.1 (s,
1H, NH). Anal. (C19H18ClN5OS), C, H, N.
1-{2-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-
yl]acetyl}-4-(3-methylphenyl) thiosemicarbazide (8p)
1-[2-(3-Methyl-5-phenyl-1H-pyrazol-1-yl)acetyl]-4-(4-
methoxyphenyl) thiosemicarbazide (8k)
Yield 92%, m.p. 160–162°C. IR: mmax/cm-1 3209 (NH),
1690 (C=O), 1607, 1539, 1201. H-NMR (DMSO-d6): d
1
2.3 (s, 3H, CH3), 2.5 (s, 3H, CH3), 5.3 (s, 2H, CH2), 6.7 (s,
1H, pyrazole H-4), 7.5–8.5 (m, 8H, arom. H), 10.3 (s, 2H,
2NH), 10.9 (br.s, 1H, NH). Anal. (C20H20ClN5OS), C, H,
N.
Yield 75%, m.p. 174–176°C. IR: mmax/cm-1 3295 (NH),
1674 (C=O), 1617, 1551, 1173. 1H-NMR (DMSO-d6): d 2.4
(s, 3H, CH3), 4.2 (s, 3H, OCH3), 5.2 (s, 2H, CH2), 6.7 (s, 1H,
pyrazole H-4), 7.3–8.4 (m, 9H, arom. H), 10.3 (br.s, 2H,
2NH), 11.3 (s, 1H, NH). Anal. (C20H21N5O2S), C, H, N.
1-{2-[-5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-
yl]acetyl}-4-(4-methoxyphenyl) thiosemicarbazide (8q)
1-[2-(3-Methyl-5-phenyl-1H-pyrazol-1-yl)acetyl]-4-(4-
nitrophenyl) thiosemicarbazide (8l)
Yield 75%, m.p. 167–169°C. IR: mmax/cm-1 3219 (NH),
1693 (C=O), 1605, 1512, 1177. H-NMR (DMSO-d6): d
1
Yield 85%, m.p. 180–181°C. IR: mmax/cm-1 3218 (NH),
1693 (C=O), 1597, 1555, 1188 .1H-NMR (DMSO-d6): d
2.4 (s, 3H, CH3), 5.3 (s, 2H, CH2), 6.8 (s, 1H, pyrazole H-
4), 8.1–9.2 (m, 9H, arom. H), 10.8 (br.s, 2H, 2NH), 11.2 (s,
1H, NH). Anal. (C19H18N6O3S), C, H, N.
2.4 (s, 3H, CH3), 4.2 (s, 3H, OCH3), 5.2 (s, 2H, CH2), 6.7
(s, 1H, pyrazole H-4), 7.4–8.6 (m, 9H, arom. H ? NH),
10.4 (s, 2H, 2NH). Anal. (C20H20ClN5O2S), C, H, N.
1-{2-[-5-(4-Chlorophenyl)3-methyl-1H-pyrazol-1-
yl]acetyl}-4-(4-nitrophenyl) thiosemicarbazide (8r)
1-{2-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-
yl]acetyl}-4-ethylthiosemicarbazide (8m)
Yield 80%, m.p. 180–181°C. IR: mmax/cm-1 3191 (NH),
1690 (C=O), 1599, 1549, 1201. H-NMR (DMSO-d6): d
1
Yield 70%, m.p. 204–205°C. IR: mmax/cm-1 3256, 3158
(NH), 1696 (C=O), 1554, 1493, 1229.1H-NMR (DMSO-
d6): d 1.2 (t, 3H, CH2CH3), 2.5 (s, 3H, CH3), 3.8 (q, 2H,
CH2CH3), 5.2 (s, 2H, CH2), 6.6 (s, 1H, pyrazole H-4),
7.4–7.7 (m, 4H, arom. H), 8.2 (s, 1H, NH), 9.3 (s, 1H, NH),
10.0 (s, 1H, NH) Anal. (C15H18ClN5OS), C, H, N.
2.5 (s, 3H, CH3), 5.2 (s, 2H, CH2), 6.7 (s, 1H, pyrazole H-
4), 8.0–9.1 (m, 8H, arom. H), 10.7 (s, 3H, 3NH). Anal.
(C19H17ClN6O3S), C, H, N.
General method for the preparation of 5-(3-methyl-5-
substituted-1H-pyrazol-1-ylmethyl)-4-substituted-2H-
1,2,4-triazole-3-thiones (9a–d, f–h, j, k, m, o–q)
1-{2-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-
yl]acetyl}-4-cyclohexyl thiosemicarbazide (8n)
A 2N sodium hydroxide solution (2 ml) was added to a
solution of the appropriate 8a–d, f–h, j, k, m, and
o–q (5 mmol) in ethanol (50 ml). The reaction mixture was
then refluxed for 7 h, cooled, filtered, and the filtrate was
acidified with 2N hydrochloric acid. The separated solid
was collected, washed, and crystallized from ethanol
(Scheme 3).
Yield 60%, m.p. 114–115°C. IR: mmax/cm-1 3273 (NH),
1
1703 (C=O), 1620, 1551, 1224. H-NMR (DMSO-d6): d
0.9–2.2 (m, 11H, cyclohexyl), 2.4 (s, 3H, CH3), 5.2 (s, 2H,
CH2), 6.8 (s, 1H, pyrazole H-4), 8.2–8.9 (m, 4H, arom. H),
10.2 (br.s, 2H, 2NH), 11.2 (s, 1H, NH). MS m/z (%) = 407
123

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Med Chem Res (2012) 21:1722–1733
5-(3,5-Dimethyl-1H-pyrazol-1-yl methyl)-4-ethyl-2H-1,2,4-
triazole-3-thione (9a)
5-(3-Methyl-5-phenyl-1H-pyrazol-1-ylmethyl)-4-ethyl-2H-
1,2,4-triazole-3-thione (9g)
Yield 65%, m.p. 201–203°C. IR: mmax/cm-13442 (NH),
1558, 1510, 1186. 1H-NMR (DMSO-d6): d1.2 (t, 3H,
CH2CH3), 2.5 (s, 3H, CH3), 4.4 (q, 2H, CH2CH3), 5.8 (s,
2H, CH2), 6.4 (s, 1H, pyrazole H-4), 14.4 (s, 1H, NH). MS:
m/z (%) = 237 (M?, 100), 209 (19), 109 (68), 95 (46), 68
(24). Anal. (C10H15N5S), C, H, N.
Yield 80%, m.p. 174–175°C. IR: mmax/cm-1 3435 (NH),
1575, 1551, 1187. 1H-NMR (DMSO-d6): d 1.2 (t, 3H,
CH2CH3), 2.5 (s, 3H, CH3), 4.3 (q, 2H, CH2CH3), 5.8 (s,
2H, CH2), 6.6 (s, 1H, pyrazole H-4), 8.1 (m, 5H, arom. H),
12.9 (s, 1H, NH). Anal. (C15H17N5S), C, H, N.
5-(3-Methyl-5-phenyl-1H-pyrazol-1-ylmethyl)-4-propyl-
2H-1,2,4-triazole-3-thione (9h)
5-(3,5-Dimethyl-1H-pyrazol-1-yl methyl)-4-propyl-2H-
1,2,4-triazole-3-thione (9b)
Yield 78%, m.p. 108–110°C. IR: mmax/cm-1 3422 (NH),
1653, 1576, 1186. 1H-NMR (DMSO-d6): d 0.9(t, 3H,
CH2CH2CH3), 1.7(m, 2H, CH2CH2CH3) 2.5 (s, 3H, CH3)
4.3 (t, 2H, CH2CH2CH3), 5.2 (s, 2H, CH2), 5.9 (s, 2H,
CH2), 6.8 (s, 1H, pyrazole H-4), 8.2(m, 5H, arom-H),
12.9(s, 1H, NH). Anal. (C16H19N5S), C, H, N.
Yield 73%, m.p. 184–186°C. IR: mmax/cm-1 3368 (NH),
1644, 1564, 1141. 1H-NMR (DMSO-d6): d0.8 (t, 3H,
CH2CH2CH3), 1.4 (m, 2H, CH2CH2CH3), 2.3 (s, 3H, CH3),
2.4 (s, 3H, CH3), 3.8 (t, 2H, CH2CH2CH3), 5.4 (s, 2H,
CH2), 5.9 (s, 1H, pyrazole H-4), 13.8 (s, 1H, NH). MS: m/z
(%) = 251 (M?, 85), 208 (100), 109 (59), 95 (46), 68 (9).
Anal. (C11H17N5S), C, H, N.
5-(3-Methyl-5-phenyl-1H-pyrazol-1-ylmethyl)-4-(3-
methylphenyl)-2H-1,2,4-triazole-3-thione (9j)
Yield 82%, m.p. 188–189°C. IR: mmax/cm-1 3447 (NH),
1607, 1592, 1177. 1H-NMR (DMSO-d6): d 2.3 (s, 3H,
CH3), 2.5 (s, 3H, CH3), 5.5 (s, 2H, CH2), 6.4 (s, 1H, pyr-
azole H-4), 7.2–8.1 (m, 9H, arom. H), 13.8 (s, 1H, NH).
Anal. (C20H19N5S), C, H, N.
5-(3,5-Dimethyl-1H-pyrazol-1-yl methyl)-4-cyclohexyl-2H-
1,2,4-triazole-3-thione (9c)
Yield 82%, m.p. 268–269°C. IR: mmax/cm-1 3422 (NH),
1650, 1564, 1184. 1H-NMR (DMSO-d6): d 0.9–2.1 (m,
11H, cyclohexyl), 2.3 (s, 3H, CH3), 2.4 (s, 3H, CH3),
5.9 (s, 2H, CH2), 6.4 (s, 1H, pyrazole H-4), 13.5 (s, 1H,
NH). MS: m/z (%) = 291 (M?, 40), 208 (100),
109 (35), 95 (49), 68 (6), 55 (45). Anal. (C14H21N5S),
C, H, N.
5-(3-Methyl-5-phenyl-1H-pyrazol-1-ylmethyl)-4-(4-
methoxyphenyl)-2H-1,2,4-triazole-3-thione (9k)
Yield 75%, m.p. 190–192°C. IR: mmax/cm-1 3422 (NH),
1610, 1582, 1174. 1H-NMR (DMSO-d6): d 2.2 (s, 3H,
CH3), 3.8 (s, 3H, OCH3), 5.2 (s, 2H, CH2), 6.0 (s, 1H,
pyrazole H-4), 6.8–7.4 (m, 9H, arom. H), 13.8 (s, 1H, NH).
Anal. (C20H19N5OS), C, H, N.
5-(3,5-Dimethyl-1H-pyrazol-1-ylmethyl)-4-(3-
methylphenyl)-2H-1,2,4-triazole-3-thione (9d)
Yield 78%, m.p. 231–232°C. IR: mmax/cm-1 3446 (NH),
1578, 1519, 1228. 1H-NMR (DMSO-d6): d 2.3 (s, 3H,
CH3), 2.5 (s, 3H, CH3), 2.6 (s, 3H, CH3), 5.2 (s, 2H,
CH2), 6.4 (s, 1H, pyrazole H-4), 7.5–8.3 (m, 4H, arom.
H), 9.1 (br.s, 1H, NH). MS: m/z (%) = 299 (M?, 100),
208 (1), 109 (49), 95 (28), 68 (10). Anal. (C15H17N5S), C,
H, N.
5-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-ylmethyl]-
4-ethyl-2H-1,2,4-triazole-3-thione (9m)
Yield 63%, m.p. 189–190°C. IR: mmax/cm-1 3438 (NH),
1569, 1499, 1193. 1H-NMR (DMSO-d6): d 0.9 (t, 3H,
CH2CH3), 2.1 (s, 3H, CH3), 3.9 (q, 2H, CH2CH3), 5.4 (s,
2H, CH2), 6.3 (s, 1H, pyrazole H-4), 7.5–7.8 (m, 4H, arom.
H), 13.7 (s, 1H, NH). MS: m/z (%) = 335 (M?2, 37), 333
(M?, 100), 304 (17), 205 (25), 192 (20), 101 (3). Anal.
(C15H16ClN5S), C, H, N.
5-(3,5-Dimethyl-1H-pyrazol-1-yl methyl)-4-(4-
nitrophenyl)-2H-1,2,4-triazole-3-thione (9f)
Yield 50%, m.p. 226–227°C. IR: mmax/cm-1 3242 (NH),
1600, 1233. H-NMR (DMSO-d6): d 2.3 (s, 3H, CH3), 2.4
5-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-ylmethyl]-
4-phenyl-2H-1,2,4-triazole-3-thione (9o)
1
(s, 3H, CH3), 5.2 (s, 2H, CH2), 6.4 (s, 1H, pyrazole H-4),
8.2–9.2 (m, 4H, arom. H), 11.0 (s, 1H, NH). Anal.
(C14H14N6O2S), C, H, N.
Yield 63%, m.p. 227–229°C. IR: mmax/cm-1 3442 (NH),
1567, 1488, 1193. 1H-NMR (DMSO-d6): d 2.1 (s, 3H,
123

Med Chem Res (2012) 21:1722–1733
1731
[5-(3-Methyl-5-phenyl-1H-pyrazol-1-ylmethyl)-1,3,4-
thiadiazol-2-yl]-propylamine (10h)
CH3), 5.2 (s, 2H, CH2), 6.0 (s, 1H, pyrazole H-4), 7.0–7.5
(m, 9H, arom. H), 13.9 (s, 1H, NH). MS: m/z (%) = 383
(M?2, 10), 381 (M?, 36), 204 (16), 192 (21), 177 (2), 77
(7). Anal. (C19H16ClN5S), C, H, N.
Yield 54%, m.p. 226–227°C. IR: mmax/cm-1 3441 (NH),
1579, 1523. 1H-NMR (DMSO-d6):
0.9 (t, 3H,
d
CH2CH2CH3), 1.6 (m, 2H, CH2CH2CH3), 2.2 (s, 3H, CH3),
3.2 (m, 2H, CH2CH2CH3), 5.4 (s, 2H, CH2), 6.2 (s, 1H,
pyrazole H-4), 7.4–7.6 (m, 5H, arom. H), 7.8 (s, 1H, NH).
Anal. (C16H19N5S), C, H, N.
5-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-ylmethyl]-
4-(3-methylphenyl)-2H-1,2,4-triazole-3-thione (9p)
Yield 78%, m.p. 218–219°C. IR: mmax/cm-1 3445 (NH),
1604, 1580, 1177. 1H-NMR (DMSO-d6): d 2.1 (s, 3H,
CH3), 2.2 (s, 3H, CH3), 5.2 (s, 2H, CH2), 6.0 (s, 1H,
pyrazole H-4), 6.7–7.4 (m, 8H, arom. H), 15.2 (br.s, 1H,
NH). MS: m/z (%) = 397 (M?2, 26), 395 (M?, 100), 335
(11), 203 (22), 192 (32), 91 (22). Anal. (C20H18ClN5S),
C, H, N.
{5-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-ylmethyl]-
1,3,4-thiadiazol-2-yl}-(4-nitrophenyl)amine (10r)
Yield 54%, m.p. 248–250°C. IR: mmax/cm-1 3405 (NH),
1628, 1593). 1H-NMR (DMSO-d6): d 2.5 (s, 3H, CH3), 5.6
(s, 2H, CH2), 6.3 (s, 1H, pyrazole H-4), 7.6–8.3 (m, 8H,
arom. H), 11.1 (br. s, 1H, NH). MS: m/z (%) = 428 (M?2
,
7), 426 (M?, 19), 235 (13), 192 (100), 109 (38), 95 (36), 68
(5). Anal. (C19H15ClN6O2S), C, H, N.
5-[5-(4-Chlorophenyl)-3-methyl-1H-pyrazol-1-ylmethyl]-
4-(4-methoxyphenyl)-2H-1,2,4-triazole-3-thione (9q)
Yield 78%, m.p. 166–167°C. IR: mmax/cm-1 3422 (NH),
1607, 1514, 1174. 1H-NMR (DMSO-d6): d 2.6 (s, 3H,
CH3), 4.2 (s, 3H, OCH3), 5.6 (s, 2H, CH2), 6.6 (s, 1H,
pyrazole H-4), 7.2–8.4 (m, 9H, arom. H ? NH). MS: m/z
(%) = 413 (M?2, 43), 411 (M?, 100), 381 (2), 205 (18),
192 (29). Anal. (C20H18ClN5OS), C, H, N.
Anti-inflammatory activity
Compounds 3, 4, 7a–c, 8d–f, 9d, 9f and 10f, h, r were
screened for their in vivo anti-inflammatory activity by the
carrageenan-induced paw edema standard method. Adult
albino rats of either sex (pregnant female animals were
excluded) weighing 160–190 g were divided into 16 group
of 6 animals each. To reduce the variability of edema
response, rats were fasted overnight, then on the next day
(day of experiment), animals were uniformly hydrated by
giving 3 ml of water per rat orally. Indomethacin and
celecoxib (reference standards) and the tested compounds
(100 mg/kg body weight) were suspended in saline solu-
tion by the aid of few drops of Tween 80 (to improve
wettability of particles) and given orally 1 h before
induction of inflammation. The control group was given
saline solution containing few drops of Tween 80.
General method for the preparation of [5-(3-methyl-5-
substituted-1H-pyrazol-1-ylmethyl)-1,3,4-thiadiazol-2-
yl]-substituted amines (10f, h, r)
Compounds 8f, h, r (5 mmol) were separately added por-
tion wise with constant stirring to a concentrated sulfuric
acid solution (40 ml) cooled at 0°C. After complete addi-
tion, the reaction mixture was stirred for an additional 3 h
at room temperature then left overnight at the same tem-
perature. The solution was then poured onto ice-cooled
water and the separated solid was filtered, washed, dried,
and crystallized from acetic acid–water mixture as 1:2 v/v
(Scheme 3).
Carrageenan paw edema was induced according to a
modified method (Winter et al.) by subcutaneous injection
of 1% solution of carrageenan in saline (0.1 ml/rat) into the
subplanter region of the right hind paw of rats. The
thickness of rat paw was measured by mercury digital
micrometer at different time intervals, after 0, 1, 2, and 3 h
of carrageenan injection. The edema was determined from
the difference between the thickness of injected and non-
injected paws. Data were collected, checked, revised, and
analyzed. Quantitative variables from normal distribution
were expressed as mean standard error (SE). The sig-
nificant difference between groups was tested by using one-
way ANOVA followed by Dunnett’s t test at P \ 0.05 and
\0.01.
[5-(3,5-Dimethyl-1H-pyrazol-1-ylmethyl)-1,3,4-thiadiazol-
2-yl]-(4-nitrophenyl)amine (10f)
Yield 54%, m.p. 226–227°C. IR: mmax/cm-1 3436 (NH),
1602, 1581. 1H-NMR (DMSO-d6): d 2.3 (s, 3H, CH3),
2.5 (s, 3H, CH3), 5.8 (s, 2H, CH2), 6.2 (s, 1H, pyrazole
H-4), 8.1–9.0 (m, 4H, arom. H), 11.8 (br.s, 1H, NH).
MS: m/z (%) = 330 (M?, 100), 236 (31), 181 (13),
149 (10), 109 (38), 95 (36). Anal. (C14H14N6O2S),
C, H, N.
123

1732
Med Chem Res (2012) 21:1722–1733
The anti-inflammatory activity was expressed as per-
was generated using the MOE-Alpha Site Finder, and then
ligands were docked within this active site using the MOE-
Dock. The lowest energy conformation was selected and
the ligand interactions (hydrogen bonding and hydrophobic
interaction) with COX-2 were determined.
centage inhibition of edema thickness in treated animals in
comparison with the control group (Table 1).
% Inhibition of edema
ðVR ꢁ VLÞcontrol ꢁ ðVR ꢁ VLÞtreated
¼
ꢂ 100
ðVR ꢁ VLÞcontrol
where VR is the average right paw thickness; VL is the
average left paw thickness.
Acknowledgments The authors thank Dr. Ehab T. Abdel-Raheem
(Department of Pharmacology, Faculty of Pharmacy, Assiut Univer-
sity, Assiut, Egypt) for his kind interest, valuable discussions during
pharmacological screening.
Conflict of interest None.
Ulcerogenic liability
The ulcerogenic liability was determined in albino rats
following the reported method (Barsoum et al., 2006,
2009). Rats of either sex (pregnant female rats were
excluded) weighing 120–140 g were divided into five
groups of five animals each. The animals were fasted 18 h
before drug administration. Indomethacin (reference stan-
dard) and the tested compounds 3, 8f, 10f (100 mg/kg body
weight) were suspended in saline by the aid of few drops of
Tween 80 and were administered once orally for three
successive days to fasted rats. The control group animals
were given only saline with few drops of Tween 80. One
hour following the dose, the animals were sacrificed and
the stomach was removed, opened along the greater cur-
vature and rinsed with saline. The gastric mucosa was
examined with a magnifying lens (109) for the presence of
lesions and erosions. The ulcer index was calculated
(Table 2) and the degree of ulcerogenic effect was
expressed in terms of:
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