Synthesis, cyclooxygenase inhibition, anti-inflammatory evaluation, and ulcerogenic liability of new 1,3,5-triarylpyrazoline derivatives possessing a methanesulfonyl pharmacophore

Article abstract of DOI:10.1002/ardp.201600145

A new series of 1,3,5-triarylpyrazolines 13a–l was synthesized and all prepared compounds were evaluated for their in vitro COX-1/COX-2 inhibitory activity and in vivo anti-inflammatory activity. All test compounds were more selective for the COX-2 isozyme and showed good in vivo anti-inflammatory activity. Compound 13h was the most COX-2 selective compound (COX-2 selectivity index (SI)=10.23) and the most potent anti-inflammatory derivative (ED₅₀-60.1μmol/kg) in comparison with celecoxib (COX-2 SI=9.29 and ED₅₀=81.4μmol/kg). All screened compounds were less ulcerogenic (ulcer indexes (UI)=0.33–1.33) than aspirin (UI=2.33) and comparable to celecoxib (UI=0.33).

Full text of DOI:10.1002/ardp.201600145

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Arch. Pharm. Chem. Life Sci. 2016, 349, 1–7
Archiv der Pharmazie
Full Paper
Synthesis, Cyclooxygenase Inhibition, Anti-Inflammatory
Evaluation, and Ulcerogenic Liability of New
1,3,5-Triarylpyrazoline Derivatives Possessing a
Methanesulfonyl Pharmacophore
Khaled R. A. Abdellatif1, Wael A. A. Fadaly1, and Amany A. Azouz2
1
Department of Pharmaceutical Organic Chemistry, Beni-Suef University, Beni-Suef, Egypt
Faculty of Pharmacy, Department of Pharmacology and Toxicology, Beni-Suef University,
2
Beni-Suef, Egypt
A new series of 1,3,5-triarylpyrazolines 13a–l was synthesized and all prepared compounds were
evaluated for their in vitro COX-1/COX-2 inhibitory activity and in vivo anti-inflammatory activity.
All test compounds were more selective for the COX-2 isozyme and showed good in vivo
anti-inflammatory activity. Compound 13h was the most COX-2 selective compound (COX-2 selectivity
index (SI) ¼ 10.23) and the most potent anti-inflammatory derivative (ED50 ¼ 60.1 mmol/kg) in
comparison with celecoxib (COX-2 SI ¼ 9.29 and ED50 ¼ 81.4 mmol/kg). All screened compounds were
less ulcerogenic (ulcer indexes (UI) ¼ 0.33–1.33) than aspirin (UI ¼ 2.33) and comparable to celecoxib
(UI ¼ 0.33).
Keywords: 1,3,5-Triarylpyrazoline / Anti-inflammatory / Cyclooxygenase-2 inhibitors / Pyrazoline
Received: May 13, 2016; Revised: August 21, 2016; Accepted: August 23, 2016
DOI 10.1002/ardp.201600145
Additional supporting information may be found in the online version of this article at the publisher’s web-site.
:
inhibition of COX-2 over COX-1 is considered as useful
approach for treatment of inflammation with reduced
Introduction
Prostaglandins (PGs) that cause inflammation, fever, and pain
are formed by the inducible cyclooxygenase-2 (COX-2) isozyme
whereas PGs that regulate beneficial gastrointestinal cyto-
protection and renal effects are produced by the constitutive
cyclooxygenase-1 (COX-1) isozyme [1–3]. Traditional non-
steroidal anti-inflammatory drugs (NSAIDs) as aspirin (1),
ibuprofen (2), and indomethacin (3) exert their anti-inflamma-
tory effect through non-selective inhibition of both COX-1 and
COX-2; therefore their chronic use was associated with adverse
effects including gastric bleeding and ulceration [4]. Selective
gastrointestinal side effects [5, 6]. Hence, a number of
selective COX-2 inhibitors (coxibs) such as celecoxib (4),
rofecoxib (5), and valdecoxib (6) have been developed and
approved for marketing (Fig. 1). However, after the coxibs
were marketed, cardiovascular side effects accompanied their
use, ultimately prompting the withdrawal of rofecoxib (5)
and valdecoxib (6) [7]. Celecoxib (4) has not been associated
with high incidence of cardiovascular events compared
with placebo and with non-selective NSAIDs [8] but some
gastrointestinal side effects associated with its use [9–11].
Recently, we reported some diaryl and triarylpyrazolines
(7–10) as celecoxib derivatives [12–15] (Fig. 1) with compara-
ble activities to celecoxib as COX-2 selective compounds
and also some other pyrazolines [16, 17] were reported as
COX-2 selective derivatives. As part of our ongoing research
program to develop anti-inflammatory agents devoid of side
effects, we now report the synthesis, in vitro evaluation
as COX-1/COX-2 inhibitors, in vivo anti-inflammatory (AI)
Correspondence: Dr. Khaled R. A. Abdellatif, Faculty of Pharmacy,
Department of Pharmaceutical Organic Chemistry, Beni-Suef
University, Beni-Suef 62514, Egypt.
E-mail: khaled.ahmed@pharm.bsu.edu.eg
Fax: þ2-082-2317958
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Arch. Pharm. Chem. Life Sci. 2016, 349, 1–7
K. R. A. Abdellatif et al.
Archiv der Pharmazie
O
Figure 1. Chemical structures of non-selective
NSAIDs (1–3), COX-2 selective drugs (4–6),
and the reported diaryl and triarylpyrazo-
lines (7–10).
O H
O
C H 3
C O O H
O H
O
N
O
O
O
i-B u
Ib u p ro fe n (3 )
A s p irin (1 )
M e
C l
In d o m e th a c in (2 )
S O 2 N H 2
S O 2 M e
S O 2 N H 2
N
O
N
N
O
O
M e
C e le c o x ib (4 )
V a ld e c o x ib (6 )
F 3
C
R o fe c o x ib (5 )
H 3 C O 2
S
R 2
R 1
A r
F
R 3
N
N
N
N H
O H
S O 2 N H 2
R 1
=
H , O M e ; R 2 = H , O M e ; R 3
=
H , O M e , S M e
A r
=
4 -F C 6 H 4 , 3 ,4,5 -(O C H 3
)
3 C 6 H 2
(7 )
(8 )
A r
X
A r
O
X
N
N
N
N
C
H 3
S O 2N H 2
A r
=
3 -p y r id y l, 4 -p y r id y l; X
=
O , S
A r
=
4 -C lC 6 H 4 , 3 ,4 ,5 -(O C H 3
)
3C 6 H 2 ; X
=
O ,
S
(9 )
(1 0 )
Biological evaluation
activity, and ulcerogenic liability for a new series of 1,3,5-
triarylpyrazolines 13a–l in which (i) a heteroaryl moiety
(2-furyl or 2-thienyl) is attached to the central pyrazoline ring
at position 3 and (ii) a methanesulfonyl (SO2Me) moiety as
COX-2 pharmacophore in para position of the phenyl moiety
is attached to the pyrazoline ring at position 1.
In vitro cyclooxygenase inhibition assay
The COX-1/-2 inhibitory potency of compounds 13a–l was
tested by an enzyme immunoassay (EIA) [27]. The results
(Table 1) showed that all the triarylpyrazolines (13a–l) are
weak inhibitors of COX-1 isozyme (IC50 ¼ 3.52–9.41 mM range)
but exhibited moderate COX-2 isozyme inhibitory activities
(IC50 ¼ 0.38–3.41 mM range). Also, the results showed COX-2
selectivity indexes (SI) in the range of 2.46–10.23. While
the thienyl derivative (13h) had the highest COX-2 potency
(IC50 ¼ 0.38 mM) and the highest COX-2 selectivity index
(SI ¼ 10.23), the furyl derivative (13a) had the lowest COX-2
potency (IC50 ¼ 3.41 mM) and the lowest COX-2 selectivity
index (SI ¼ 2.46) in comparison with the reference drug
celecoxib (IC50 ¼ 0.79 mM, SI ¼ 9.29).
Results and discussion
Chemistry
The propen-1-one derivatives (11a–l) were prepared via base
catalyzed condensation of the appropriate aromatic aldehyde
and the corresponding ketone in methanol using reported
procedures [15–25]. Cyclocondensation of the appropriate
chalcone (11a–l) with 4-methanesulfonylphenylhydrazine-
hydrochloride (12) [26] in aqueous ethanol afforded the
respective triarylpyrazolines (13a–l) as racemic mixtures in
good yields (62–88%) (Scheme 1).
In vivo anti-inflammatory activity
The anti-inflammatory activity of the prepared triarylpyrazoline
derivatives (13a–l) were evaluated using carrageenan-induced
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1,3,5-Triarylpyrazoline Derivatives with a Methanesulfonyl Pharmacophore
Archiv der Pharmazie
N H N H 2 .H C l
A r
A r
a
X
N
X
N
O
1 1 a−l
S O 2 C H 3
12
13 a−l
S O 2 C H 3
11 g , 13 g ;
11 h , 1 3 h ;
X
=
O , A r
=
4 -C lC 6 H
1 1 a , 1 3 a ;
1 1 b , 13 b ;
1 1 c, 1 3 c;
1 1 d , 1 3 d ;
1 1 e, 1 3 e;
X
=
O , A r
S , A r
O , A r
S , A r
O , A r
=
2 -f u r y l
4
X
= S A r = 4 -C lC 6 H
X
=
=
2 -fu r y l
4
11 i, 1 3 i;
11 j , 1 3 j ;
X
=
O , A r
S , A r = 4 -C F 3
O , A r 3,4,5-
S , A r 3,4,5 -(O C H
= 4 -C F 3 C 6 H
X
=
=
=
=
2 -t h ien y l
2 -t h ien y l
4 -O C H 3 C 6 H
4
X
=
C 6 H
4
X
=
(O C H
)
3 C 6
H
2
11 k , 13 k ;
X
=
=
=
X
=
2
33C 6 H
4
11 l, 1 3 l;
X
=
)
1 1 f, 13 f;
X = S , A r = 4 -O C H 3 C 6 H
4
3
Scheme 1. General synthetic procedure for the title compounds 13a–l. Reagents and conditions: (a) EtOH (95%), reflux, 36 h.
rat paw edema assay [28]. Each compound was administered
orally (50 mg/kg) 1 h prior to induction of inflammation by
carrageenan subcutaneous injection and the anti-inflammatory
activity was then calculated based on paw-volume changes
at 3 h after carrageenan injection as presented in Table 1. A
comparable study of the anti-inflammatory activity of the test
compounds relative to celecoxib as a reference drug indicated
that the triarylpyrazoline derivatives (13a–l) showed variable
edema inhibition percentage activities of 42–100% and the
most COX-2 selective compound (thienyl derivative, 13h) was
the most potent one (100% edema inhibition) while the
furyl derivative (13c) was the least potent one (42% edema
inhibition) comparable to that of celecoxib (81%). In general,
the thienyl derivatives were more potent than the correspond-
ing furyl analogs (13d > 13c, 74, 42% edema inhibition,
respectively), (13f > 13e, 72, 55% edema inhibition, respec-
tively), (13h> 13g, 100, 58% edema inhibition, respectively),
(13j > 13i, 81, 74% edema inhibition, respectively), and
(13l > 13k, 76, 68% edema inhibition, respectively) with only
oneexception(13b < 13a, 55, 74%edemainhibition, respectively).
Table 1. In vitro COX-1, COX-2 inhibition, anti-inflammatory activity of triarylpyrazolines (13a–l) and reference drug
celecoxib.
AI activity
COX-1
COX-2
COX-2
SIb)
%Inhibition
ED50
Compound
IC50 (mM)a)
IC50 (mM)a)
(50 mg/kg)c)
(mmol/kg)d)
13a
13b
13c
13d
13e
13f
13g
13h
13i
13j
13k
13l
Celecoxib
8.41
7.59
4.98
6.98
6.67
9.41
3.52
3.89
5.74
6.98
8.95
4.12
7.34
3.41
1.97
0.65
1.74
0.98
2.53
0.41
0.38
0.69
1.44
2.41
0.86
0.79
2.46
3.85
7.66
3.95
6.80
3.71
8.58
10.23
8.31
4.84
3.71
4.79
9.29
74
55
42
74
55
72
58
100
74
81
68
76
81
–
–
–
87.6
–
85.0
–
60.1
78.3
68.9
–
69.9
81.4
a) The concentration of test compound producing 50% inhibition of ovine COX-1, COX-2 enzyme, the result is the mean of
two values obtained by assay of enzyme kits obtained from (Cayman Chemicals Inc., Ann Arbor, MI, USA).
b) The in vitro COX-2 selectivity index (COX-1 IC50/COX-2 IC50).
c) Inhibitory activity in a carrageenan-induced rat paw edema assay. The results are expressed as the %inhibition of
inflammation at 3 h after oral administration of the test compound.
d) Inhibitory activity in a carrageenan-induced rat paw edema assay. The results are expressed as the ED50 value (mmol/kg) at
3 h after oral administration of the test compound.
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Moreover, the ED50 values for the most potent six derivatives
(five thienyl derivatives 13d, 13f, 13h, 13j, 13l and only one
furyl derivative 13i) were calculated in comparison with
celecoxib. The six derivatives showed good anti-inflammatory
activities (ED50 ¼ 60.1–87.6 mmol/kg) while 13h–j and 13l
(ED50 ¼ 60.1, 78.3, 68.9, and 69.5 mmol/kg, respectively) were
more potent than celecoxib (ED50 ¼ 81.4 mmol/kg), 13d and
13f were less potent but with acceptable ED50 values
(ED50 ¼ 87.6 and 85.0 mmol/kg, respectively). The ED50 values
for the most potent six derivatives correspond with COX-2
selectivity indexes. The most potent derivatives 13h–j and13l
(ED50 ¼ 60.1, 78.3, 68.9, and 69.5 mmol/kg, respectively) are
the most COX-2 selective (SI ¼ 10.23, 8.31, 4.84, and 4.79,
compounds showed good anti-inflammatory activity, espe-
cially compounds 13h–j and 13l which are more potent than
celecoxib; (iii) substitution of the pyrazoline central ring with
2-thienyl moiety is favored over substitution with 2-furyl
moiety; and (iv) all compounds were less ulcerogenic than
aspirin and some compounds showed ulceration potential
comparable to that of celecoxib.
Experimental
Chemistry
Melting points were determined on a Griffin apparatus and
are uncorrected. Infrared (IR) spectra were recorded on a
Shimadzu 435 spectrometer using KBr discs. 1H NMR was
measured on a Bruker 400 MHz spectrometer and 13C NMR
spectra were measured on a Bruker 100 MHz spectrometer
(Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt)
in D2O or DMSO-d6 with TMS as the internal standard, where J
(coupling constant) values were estimated in hertz (Hz). Mass
spectra were run on Hewlett Packard 5988 spectrometer.
Microanalyses were performed for C, H, N at the Micro
Analytical Center, Cairo University, Egypt and were within
ꢀ0.4% of theoretical values. All other reagents, purchased
from the Acros Chemical Company, were used without further
purification. The propen-1-one derivatives (11a–l) [15–25] and
4-methanesulfonylphenylhydrazine hydrochloride (12) [26]
were prepared according to reported procedures.
respectively). The less potent derivatives 13d and 13f (ED50
¼
87.6 and 85.0 mmol/kg, respectively) are the less COX-2
selective (SI ¼ 3.95 and 3.71, respectively).
Ulcerogenic liability
The most potent compounds (13d, 13f, 13h–j, and 13l) were
subjected to further study to determine their ulcerogenic
effect (ulcer index, UI) [29] in comparison with celecoxib and
aspirin using 50 mg/kg dose. The results revealed that all
compounds were less ulcerogenic (UI ¼ 0.33–1.33) than aspirin
(UI ¼ 2.33) and comparable to celecoxib (UI ¼ 0.33) which
greatly supported our main objective to avoid gastric
ulceration caused by COX-1 inhibition (Table 2). The furyl
derivative (13l) was the most safe derivative (UI ¼ 0.33) which
is about fourfold less ulcerogenic than aspirin and showed in
our assay an ulcerogenic potential comparable to celecoxib.
The InChI codes of the investigated compounds are
provided as Supporting Information.
General method for the preparation of 1,3,5-
triarylpyrazolines (13a–l)
Conclusion
A new series of 1,3,5-triarylpyrazolines 13a–l possessing a
heteroaryl moiety (2-furyl or 2-thienyl) at position 3 of
the central pyrazoline ring was synthesized for evaluation
as selective COX-2 inhibitors, anti-inflammatory agents,
and ulcerogenic liability. Structure-activity data acquired
and biological studies showed that (i) all compounds inhibited
COX-2 more potently than COX-1; (ii) all the evaluated
A solution of the appropriate chalcone (11a–l, 0.1 mol) in
ethanol (50 mL) was heated under reflux with p-methane-
sulfonylphenylhydrazine hydrochloride (12, 0.1 mol) for 36 h,
cooled and diluted with cold water. The precipitated crude
product was filtered and recrystallized from ethanol to give
13a–l. Physical and spectral data are listed below.
3,5-Di-furan-2-yl-1-(4-methanesulfonylphenyl)-4,5-
dihydro-1H-pyrazole (13a)
Yield 66%; reddish brown solid; m.p. 200–202°C; IR (KBr disk)
2923 (C-H aliphatic), 1328, 1155 (SO2); 1H NMR (CDCl3) d 3.02
(s, 3H, SO2CH3), 3.38 (dd, J ¼ 5.6, 17.6 Hz, 1H, pyrazole H-4),
3.71 (dd, J ¼ 12.0, 13.2 Hz, 1H, pyrazole H0-4), 5.44 (dd, J ¼ 5.2,
12.0 Hz, 1H, pyrazole H-5), 6.24 (d, J ¼ 2.8 Hz, 1H, furyl H-4),
6.33 (s, 1H, furyl H-5), 6.54 (d, J ¼ 1.2 Hz, 1H, furyl H-4), 6.73 (d,
J ¼ 3.2 Hz, 1H, furyl H-5), 7.20 (d, J ¼ 8.8 Hz, 2H, methanesul-
fonylphenyl H-2, H-6), 7.28 (s, 1H, furyl H-3), 7.57 (s, 1H, furyl
H-3), 7.74 (d, J ¼ 8.4 Hz, 2H, methanesulfonylphenyl H-3, H-5);
13C NMR (CDCl3) d 40.08, 44.95, 56.94, 107.61, 110.58, 111.22,
111.95, 112.88, 128.34, 128.85, 129.47, 142.14, 144.23, 147.25,
Table 2. Ulcerogenic effect for most potent derivatives
13d, 13f, 13h–j, and 13l, celecoxib, and aspirin.
Compound
UI
13d
13f
13g
13h
13i
13j
13l
Celecoxib
0.67
0.41
0.67
1.33
0.33
1.00
0.33
0.33
2.33
147.72, 151.87; MS (m/z, relative abundance %): 356 (Mþ.
,
100.00). Anal. calcd. for C18H16N2O4S: C, 60.66; H, 4.53; N, 7.86.
Found: C, 60.29; H, 4.32; N, 7.55.
Aspirin
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5-Furan-2-yl-1-(4-methanesulfonylphenyl)-3-thiophen-2-
yl-4,5-dihydro-1H-pyrazole (13b)
SO2CH3), 3.13 (dd, J ¼ 3.6, 15.6 Hz, 1H, pyrazole H-4), 3.76
(s, 3H, OCH3), 3.85 (dd, J ¼ 3.6, 15.6 Hz, 1H, pyrazole H0-4), 5.30
(dd, J ¼ 5.6, 12.0 Hz, 1H, pyrazole H-5), 6.52 (d, J ¼ 1.6 Hz, 1H,
furyl H-4), 6.53 (d, J ¼ 2.0 Hz, 1H, furyl H-5), 6.68 (d, J ¼ 3.2 Hz,
2H, methoxyphenyl H-2, H-6), 6.87 (d, J ¼ 2.0 Hz, 2H, methoxy-
phenyl H-3, H-5), 7.17 (d, J ¼ 9.2 Hz, 2H, methanesulfonyl-
phenyl H-2, H-6), 7.56 (d, J ¼ 9.2 Hz, 1H, furyl H-3), 7.68 (d,
J ¼ 9.2 Hz, 2H, methanesulfonylphenyl H-3, H-5); 13C NMR
(CDCl3) d 43.49, 44.94, 62.55, 111.10, 111.90, 112.47, 112.79,
126.84, 128.34, 129.33, 130.35, 132.70, 141.79, 147.45, 147.64,
159.38; MS (m/z, relative abundance %): 396 (Mþ., 100.00).
Anal. calcd. for C21H20N2O4S: C, 63.62; H, 5.08; N, 7.07. Found:
C, 63.53; H, 4.85; N, 7.23.
Yield 76%; reddish brown solid; m.p. 300–302°C; IR (KBr disk)
1
2925 (C-H aliphatic), 1352, 1141 (SO2); H NMR (CDCl3) d 3.02
(s, 3H, SO2CH3), 3.43 (dd, J ¼ 4.8, 13.2 Hz, 1H, pyrazole H-4), 3.76
(dd, J ¼ 12.4, 16.8 Hz, 1H, pyrazole H0-4), 5.45 (dd, J ¼ 4.8,
12.4 Hz, 1H, pyrazoleH-5), 6.26(s,1H, furylH-4), 6.33(s, 1H, furyl
H-5), 7.08(d, J ¼ 3.2 Hz, 1H,thienylH-4), 7.09(m, 1H,thienylH-5,
2H,methanesulfonylphenylH-2,H-6),7.38(s,1H,furylH-3),7.41
(d, J ¼ 4.8 Hz, 1H, thienyl H-3), 7.98 (d, J ¼ 6.8 Hz, 2H, methane-
sulfonylphenyl H-3, H-5); 13C NMR (CDCl3) d 41.00, 44.70, 57.05,
105.74, 107.60, 110.60, 127.40, 127.56, 127.63, 127.94, 135.40,
142.75, 143.45, 146.06, 147.75, 151.97; MS (m/z, relative
abundance %):372 (Mþ., 100.00). Anal. calcd. forC18H16N2O3S2:
C, 58.04; H, 4.33; N, 7.52. Found: C, 58.32; H, 3.96; N, 7.39.
1-(4-Methanesulfonylphenyl)-5-(4-methoxyphenyl)-3-
thiophen-2-yl-4,5-dihydro-1H-pyrazole (13f)
3-Furan-2-yl-1-(4-methanesulfonylphenyl)-5-thiophen-2-
yl-4,5-dihydro-1H-pyrazole (13c)
Yield 74%; yellow solid; m.p. 160–162°C; IR (KBr disk) 2923
(C-H aliphatic), 1348, 1141 (SO2); 1H NMR (CDCl3) d 2.99 (s, 3H,
SO2CH3), 3.18 (dd, J ¼ 6.0, 17.2 Hz, 1H, pyrazole H-4), 3.80
(s, 3H, OCH3), 3.87 (dd, J ¼ 12.4, 17.2 Hz, 1H, pyrazole H0-4),
5.31 (dd, J ¼ 6.0, 17.2 Hz, 1H, pyrazole H-5), 6.88 (d, J ¼ 8.4 Hz,
2H, methoxyphenyl H-2, H-6), 7.06 (d, J ¼ 4.0 Hz, 1H, thienyl
H-4), 7.09 (d, J ¼ 8.4 Hz, 2H, methoxyphenyl H-3, H-5), 7.14 (d,
J ¼ 3.2 Hz, 1H, thienyl H-5), 7.15 (d, J ¼ 8.4 Hz, 2H, methane-
sulfonylphenyl H-2, H-6), 7.40 (d, J ¼ 4.8 Hz, 1H, thienyl H-3),
7.68 (d, J ¼ 8.4 Hz, 2H, methanesulfonylphenyl H-3, H-5);
13C NMR (CDCl3) d 44.44, 44.95, 55.32, 63.13, 112.71, 114.78,
126.86, 127.25, 127.55, 128.39, 128.82, 128.92, 132.85, 135.66,
145.75, 147.66, 159.38; MS (m/z, relative abundance %): 412
(Mþ., 21.00). Anal. calcd. for C21H20N2O3S2: C, 61.14; H, 4.89;
N, 6.79. Found: C, 61.41; H, 4.51; N, 6.93.
Yield 76%; reddish brown solid; m.p. 228–230°C; IR (KBr disk)
2923 (C-H aliphatic), 1373, 1141 (SO2); 1H NMR (CDCl3) d 3.01
(s, 3H, SO2CH3), 3.29 (dd, J ¼ 5.2, 17.2 Hz, 1H, pyrazole H-4),
3.82 (dd, J ¼ 12.0, 17.2 Hz, 1H, pyrazole H0-4), 5.62 (dd, J ¼ 5.2,
12.0 Hz, 1H, pyrazole H-5), 6.53 (dd, J ¼ 1.6, 3.2 Hz, 1H, furyl
H-4), 6.72 (d, J ¼ 3.2 Hz, 1H, furyl H-5), 6.95 (dd, J ¼ 3.6, 4.8 Hz,
1H, thienyl H-4), 7.37 (d, J ¼ 3.21H, thienyl H-5), 7.20 (d,
J ¼ 9.2 Hz, 2H, methanesulfonylphenyl H-2, H-6), 7.24 (d,
J ¼ 4.8 Hz, 1H, furyl H-3), 7.57 (d, J ¼ 3.6 Hz, 1H, thienyl H-3),
7.73 (d, J ¼ 9.2 Hz, 2H, methanesulfonylphenyl H-3, H-5);
13C NMR (CDCl3) d 43.74, 44.93, 58.92,111.32, 111.52, 113.09,
124.69, 125.46, 125.78, 127.24, 129.67, 141.95, 143.87, 144.28,
147.23, 147.73; MS (m/z, relative abundance %): 372 (Mþ.
,
100.00). Anal. calcd. for C18H16N2O3S2: C, 58.04; H, 4.33;
N, 7.52. Found: C, 58.23; H, 4.64; N, 7.19.
5-(4-Chlorophenyl)-3-furan-2-yl-1-(4-
methanesulfonylphenyl)-4,5-dihydro-1H-pyrazole (13g)
Yield 85%; pale brown solid; m.p. 160–162°C; IR (KBr disk)
2919 (C-H aliphatic), 1375, 1141 (SO2); 1H NMR (CDCl3) d 2.85
(s, 3H, SO2CH3), 3.03 (dd, J ¼ 4.4, 17.2 Hz, 1H, pyrazole H-4),
3.76 (dd, J ¼ 12.0, 17.2 Hz, 1H, pyrazole H0-4), 5.23 (dd, J ¼ 5.6,
12.4 Hz, 1H, pyrazole H-5), 6.43 (dd, J ¼ 1.6, 3.6 Hz, 1H, furyl
H-4), 6.60 (d, J ¼ 3.2 Hz, 1H, furyl H-5), 6.98 (d, J ¼ 8.8 Hz, 2H,
chlorophenyl H-2, H-6), 7.10 (d, J ¼ 8.4 Hz, 2H, chlorophenyl
H-3, H-5), 7.26 (d, J ¼ 10.0 Hz, 2H, methanesulfonylphenyl H-2,
H-6), 7.47 (d, J ¼ 3.6 Hz, 1H, furyl H-3), 7.60 (d, J ¼ 8.8 Hz, 2H,
methanesulfonylphenyl H-3, H-5); 13C NMR (CDCl3) d 43.35,
44.93, 62.36, 111.30, 111.97, 112.79, 125.22, 127.05, 128.50,
129.49, 134.04, 139.18, 141.70, 144.30, 147.18, 147.40; MS
(m/z, relative abundance %): 400 (Mþ., 100.00). Anal. calcd.
for C20H17ClN2O3S: C, 59.92; H, 4.27; N, 6.99. Found: C, 59.66;
H, 3.87; N, 7.12.
1-(4-Methanesulfonylphenyl)-3,5-di-thiophen-2-yl-4,5-
dihydro-1H-pyrazole (13d)
Yield 82%; reddish brown solid; m.p. 218–220°C; IR (KBr disk)
2925 (C-H aliphatic),1388, 1138 (SO2); 1H NMR (CDCl3) d 3.01
(s, 3H, SO2CH3), 3.34 (dd, J ¼ 5.6, 16.4 Hz, 1H, pyrazole H-4),
3.87 (dd, J ¼ 11.6, 16.4 Hz, 1H, pyrazole H0-4), 5.63 (dd, J ¼ 5.6,
11.6 Hz, 1H, pyrazole H-5), 6.95 (dd, J ¼ 3.6, 4.4 Hz, 1H, thienyl
H-4), 7.01 (d, J ¼ 2.8 Hz, 1H, thienyl H-5), 7.08 (dd, J ¼ 4.0,
4.4 Hz, 1H, thienyl H-4), 7.18 (s, 1H, thienyl H-5), 7.19 (d,
J ¼ 8.8 Hz, 2H, methanesulfonylphenyl H-2, H-6), 7.24 (d,
J ¼ 5.2 Hz, 1H, thienyl H-3), 7.47 (d, J ¼ 5.2 Hz, 1H, thienyl H-3),
7.72 (d, J ¼ 8.8 Hz, 2H, methanesulfonylphenyl H-3, H-5);
13C NMR (CDCl3) d 44.58, 44.94, 59.49, 113.03, 125.46, 125.62,
126.28, 127.25, 127.48, 127.58, 127.63, 135.39, 139.16, 144.03,
145.92, 147.78; MS (m/z, relative abundance %): 388 (Mþ.
,
93.00). Anal. calcd. for C18H16N2O2S3: C, 55.64; H, 4.15; N, 7.21.
Found: C, 55.82; H, 4.33; N, 6.95.
5-(4-Chlorophenyl)-1-(4-methanesulfonylphenyl)-3-
thiophen-2-yl-4,5-dihydro-1H-pyrazole (13h)
3-Furan-2-yl-1-(4-methanesulfonylphenyl)-5-(4-methoxy-
phenyl)-4,5-dihydro-1H-pyrazole (13e)
Yield 69%; orange solid; m.p. 136–138°C; IR (KBr disk) 2979
(C-H aliphatic), 1345, 1145 (SO2); 1H NMR (CDCl3) d 3.04 (s, 3H,
SO2CH3), 3.17 (dd, J ¼ 5.6, 16.8 Hz, 1H, pyrazole H-4), 3.90 (dd,
J ¼ 12.4, 17.2 Hz, 1H, pyrazole H0-4), 5.34 (dd, J ¼ 5.6, 12 Hz, 1H,
Yield 69%; yellow solid; m.p. 222–224°C; IR (KBr disk) 2925
(C-H aliphatic), 1375, 1140 (SO2); 1H NMR (CDCl3) d 3.00 (s, 3H,
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pyrazole H-5), 7.06 (m, 2H, chlorophenyl H-2, H-6, 1H, thienyl
H-4), 7.14 (d, J ¼ 3.6 Hz, 1H, thienyl H-5), 7.21 (d, J ¼ 6.8 Hz,
2H, chlorophenyl H-3, H-5), 7.33 (d, J ¼ 8.0 Hz, 2H, methane-
sulfonylphenylH-2, H-6), 7.41 (d, J ¼ 5.2 Hz, 1H, thienyl H-3),
7.33 (d, J ¼ 8.4 Hz, 2H, methanesulfonylphenyl H-3, H-5);
13C NMR (CDCl3) d 44.29, 44.54, 62.93, 106.89, 112.72, 128.02,
128.17, 128.92, 129.34, 134.03, 135.24, 135.32, 135.38, 138.81,
148.61; MS (m/z, relative abundance %): 416 (Mþ., 100.00).
Anal. calcd. for C20H17ClN2O2S2: C, 57.61; H, 4.11; N, 6.72.
Found: C, 57.42; H, 4.05; N, 6.88.
1H, furyl H-5), 7.03 (d, J ¼ 8.0 Hz, 2H, methanesulfonylphenyl
H-2, H-6), 7.71 (d, J ¼ 2.0 Hz, 1H, furyl H-3), 7.73 (d, J ¼ 8.0 Hz,
2H, methanesulfonylphenyl H-3, H-5); 13C NMR (CDCl3)
d 42.55, 43.92, 55.16, 59.84, 62.49, 101.19, 105.19, 106.17,
110.52, 111.86, 123.86, 127.29, 128.40, 136.63, 140.93, 141.60,
146.85, 153.09; MS (m/z, relative abundance %): 456 (Mþ.
,
100.00). Anal. calcd. for C23H24N2O6S: C, 60.51; H, 5.30; N, 6.14.
Found: C, 60.83; H, 5.48; N, 5.95.
1-(4-Methanesulfonylphenyl)-3-thiophen-2-yl-5-(3,4,5-
trimethoxyphenyl)-4,5-dihydro-1H-pyrazole (13l)
3-Furan-2-yl-1-(4-methanesulfonylphenyl)-5-(4-
Yield 88%; buff solid; m.p. 220–222°C; IR (KBr disk) 2933 (C-H
aliphatic), 1320, 1132 (SO2); 1H NMR (CDCl3) d 3.02 (s, 3H,
SO2CH3), 3.22 (dd, J ¼ 5.6, 16.8 Hz, 1H, pyrazole H-4), 3.83 (s,
6H, 3,5-dimethoxy-phenyl), 3.85 (s, 3H, 4-methoxy-phenyl),
3.89 (dd, J ¼ 12.4, 16.8 Hz, 1H, pyrazole H0-4), 5.24 (dd, J ¼ 6.4,
12.4 Hz, 1H, pyrazole H-5), 6.43 (s, 2H, 3,4,5-trimethoxyphenyl
H-2, H-6), 7.08 (d, J ¼ 3.2 Hz, 1H, thienyl H-4), 7.11 (d,
J ¼ 8.4 Hz, 2H, methanesulfonylphenyl H-2, H-6), 7.16 (d,
J ¼ 3.2 Hz, 1H, thienyl H-5), 7.42 (d, J ¼ 3.2 Hz, 1H, thienyl H-3),
7.72 (d, J ¼ 8.4 Hz, 2H, methanesulfonylphenyl H-3, H-5);
13C NMR (CDCl3) d 44.53, 44.93, 56.26, 60.87, 64.16, 102.21,
112.84, 127.40, 127.60, 127.90, 128.86, 129.35, 135.45, 136.62,
137.66, 145.94, 147.97, 154.12; MS (m/z, relative abundance
%): 472 (Mþ., 1.15). Anal. calcd. for C23H24N2O5S2: C, 58.46;
H, 5.12; N, 5.93. Found: C, 58.79; H, 5.33; N, 6.12.
trifluoromethylphenyl)-4,5-dihydro-1H-pyrazole (13i)
Yield 64%; reddish brown solid; m.p. 258–260°C; IR (KBr disk)
2927 (C-H aliphatic), 1324, 1141 (SO2); 1H NMR (CDCl3) d 2.92
(s, 3H, SO2CH3), 3.05 (dd, J ¼ 5.6, 17.6 Hz, 1H, pyrazole H-4),
3.80 (dd, J ¼ 12.4, 17.2 Hz, 1H, pyrazole H0-4), 5.32 (dd, J ¼ 5.6,
12.4 Hz, 1H, pyrazole H-5), 6.44 (s, 1H, furyl H-4), 6.62 (d,
J ¼ 3.2 Hz, 1H, furyl H-5), 6.98 (d, J ¼ 8.8 Hz, 2H, trifluoro-
methylphenyl H-2, H-6), 7.30 (d, J ¼ 8.0 Hz, 2H, trifluoro-
methylphenyl H-3, H-5), 7.48 (s, 1H, furyl H-3), 7.54 (d,
J ¼ 8.0 Hz, 2H, methanesulfonylphenyl H-2, H-6), 7.62 (d,
J ¼ 8.8 Hz, 2H, methanesulfonylphenyl H-3, H-5); 13C NMR
(CDCl3) d 43.50, 44.22, 64.50, 106.08, 106.40, 111.76, 122.36,
124.27, 124.91, 124.95, 127.58, 127.76, 128.04, 138.18, 141.75,
142.66, 144.84; MS (m/z, relative abundance %): 434 (Mþ.
,
38.00). Anal. calcd. for C21H17F3N2O3S: C, 58.06; H, 3.94;
N, 6.45. Found: C, 58.32; H, 3.57; N, 6.22.
Biological evaluation
In vitro cyclooxygenase inhibition assay
1-(4-Methanesulfonylphenyl)-3-thiophen-2-yl-5-(4-
The ability of the tested compounds to inhibit ovine COX-1
and COX-2 isozymes was measured using colorimetric COX
Inhibitor Screening Assay Kit (catalog no. 560131, Cayman
Chemical, Ann Arbor, MI, USA) following the manufacturer’s
instructions and as mentioned before [27]. Different concen-
trations of celecoxib or tested compounds were incubated
with the enzymes for a period of 5 min at 25°C followed by an
addition of the colorimetric substrate and arachidonic acid,
then the absorbance was measured at 590 nm using plate
reader.
trifluoromethylphenyl)-4,5-dihydro-1H-pyrazole (13j)
Yield 78%; brown solid; m.p. 260–262°C; IR (KBr disk) 2973
(C-H aliphatic), 1325, 1145 (SO2); 1H NMR (CDCl3) d 3.00 (s, 3H,
SO2CH3), 3.19 (dd, J ¼ 5.6, 16.8 Hz, 1H, pyrazole H-4), 3.95 (dd,
J ¼ 12.0, 16.8 Hz, 1H, pyrazole H0-4), 5.42 (dd, J ¼ 5.6, 12 Hz, 1H,
pyrazole H-5), 7.05 (d, J ¼ 4.4 Hz, 2H, trifluoromethylphenyl
H-2, H-6), 7.07 (d, J ¼ 4.0 Hz, 1H, thienyl H-4), 7.15 (d,
J ¼ 3.6 Hz, 1H, thienyl H-5), 7.40 (m, 3H, trifluoromethylphenyl
H-3, H-5, thienyl H-3), 7.63 (d, J ¼ 4.4 Hz, 2H, methanesulfonyl-
phenyl H-2, H-6), 7.71 (d, J ¼ 8.8 Hz, 2H, methanesulfonyl-
phenyl H-3, H-5); 13C NMR (DMSO-d6) d 44.21, 44.92, 63.04,
107.37, 112.71, 125.02, 125.16, 127.62, 127.69, 128.15, 128.60,
129.00, 129.07, 130.73, 135.14, 145.63, 147.35; MS (m/z,
relative abundance %): 450 (Mþ., 100.00). Anal. calcd. for
In vivo anti-inflammatory activity
Animals: Male Wister albino rats with average body weight of
120–150 g were used in the experiments. The animals were
kept under controlled environment, humidity 60 ꢀ 10%, light
period of 12 h/day, and temperature 27 ꢀ 2°C with access to
food and water. The experimental procedures were carried
out in compliance with the Institutional Animal Ethics
Committee regulations. All experiments were performed in
the morning according to the guidelines for the care of
laboratory animals.
Carrageenan induced rat paw edema: The anti-inflamma-
tory activity of the synthesized compounds was determined
in vivo by carragenan-induced paw edema method in
rats [28]. Rats were divided into 14 groups, the first group
was administered vehicle; the second one was administrated
celecoxib (50 mg/kg) while the remaining groups were
C
21H17F3N2O2S2: C, 55.99; H, 3.80; N, 6.22. Found: C, 55.64;
H, 3.63; N, 5.94.
3-Furan-2-yl-1-(4-methanesulfonylphenyl)-5-(3,4,5-
trimethoxyphenyl)-4,5-dihydro-1H-pyrazole (13k)
Yield 62%; buff solid; m.p. 240–242°C; IR (KBr disk) 2936 (C-H
aliphatic), 1318, 1145 (SO2); 1H NMR (CDCl3) d 2.93 (s, 3H,
SO2CH3), 3.08 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4), 3.72 (s,
6 H, 3,5-dimethoxy-phenyl), 3.75 (s, 3H, 4-methoxy-phenyl),
3.85 (dd, J ¼ 17.2, 11.6 Hz, 1H, pyrazole H0-4), 5.16 (dd, J ¼ 12.0,
6.0 Hz, 1H, pyrazole H-5), 6.37 (s, 2H, 3,4,5-trimethoxyphenyl
H-2, H-6), 6.44 (d, J ¼ 2.0 Hz, 1H, furyl H-4), 6.60 (d, J ¼ 2.0 Hz,
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administrated test compounds (13a–l, 50 mg/kg, and one
group per one compound). One hour after administration of
vehicle, test compounds or celecoxib paw edema was induced
by subcutaneous injection of 1% carrageenan in saline
(0.05 mL/rat) into the left hind paw of each rat. Paw thickness
of each rat was measured after 3 h of carrageenan injection,
and then the change in thickness and the %inhibition of paw
edema were calculated.
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Additionally, the ED50 values for the most potent deriva-
tives (13d, 13f, 13h–j, and 13l) were calculated using three
different doses, and paw thickness of each rat was measured
after 3 h of carrageenan injection according to the reported
procedure [28].
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Ulcerogenic liability
The ulcerogenic effect of 13d, 13f, 13h–j, and 13l, celecoxib,
and aspirin was evaluated using the previously reported
procedures [27]. Rats were divided into nine groups and
fasted for 18 h before drug administration. The control group
received the vehicle (2.5% Tween 80). Other groups received
test compounds, celecoxib or aspirin as reference drugs at a
dose of 50 mg/kg. After 2 h, animals were fed. Rats were given
the required dose orally for 3 successive days. After 2 h of the
last dose, rats were sacrificed; the stomach of each rat was
removed then opened along the greater curvature and rinsed
with saline. In order to examine the stomach, it was stretched
by pins on a corkboard. The gastric mucosa was carefully
inspected for the occurrence of ulcers with the aid of an
illuminated magnifying lens (10ꢁ), then ulcer index was
calculated according to the method described by Cho and
Ogle [29]. Lesions were counted and measured along the
greater diameter using transparent ruler. Every five hemor-
rhagic spots were considered equivalent to 1 mm of ulcer. The
ulcer index (mm) was calculated from the sum of the total
length of ulcers and hemorrhagic spots in each stomach.
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The authors have declared no conflicts of interest.
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