Synthesis, cyclooxygenase inhibition, anti-inflammatory evaluation and ulcerogenic liability of new 1,5-diarylpyrazole derivatives

Article abstract of DOI:10.1080/14756366.2016.1201815

A new series of 1,5-diarylpyrazoles 10a–l was designed and synthesized for evaluation as COX inhibitors and as anti-inflammatory agents. All compounds were more selective for COX-2 isozyme and showed good in vivo anti-inflammatory activity. Compound 10e was the most COX-2 selective compound (S.I. = 10.67) and the most potent anti-inflammatory derivative (ED₅₀ = 46 μmol/kg) which is approximately 11-folds more potent than ibuprofen (ED₅₀ = 499 μmol/kg) and had 2/3 potency of celecoxib (ED₅₀ = 31 μmol/kg). All compounds were less ulcerogenic (ulcer indexes = 1.20–4.61) than ibuprofen (ulcer index = 20.25) and comparable to celecoxib (ulcer index = 2.90).

Full text of DOI:10.1080/14756366.2016.1201815

Journal of Enzyme Inhibition and Medicinal Chemistry
ISSN: 1475-6366 (Print) 1475-6374 (Online) Journal homepage: http://www.tandfonline.com/loi/ienz20
Synthesis, cyclooxygenase inhibition, anti-
inflammatory evaluation and ulcerogenic liability
of new 1,5-diarylpyrazole derivatives
Khaled R. A. Abdellatif, Wael A. A. Fadaly, Waleed A. M. Ali & Gehan M. Kamel
To cite this article: Khaled R. A. Abdellatif, Wael A. A. Fadaly, Waleed A. M. Ali & Gehan
M. Kamel (2016): Synthesis, cyclooxygenase inhibition, anti-inflammatory evaluation and
ulcerogenic liability of new 1,5-diarylpyrazole derivatives, Journal of Enzyme Inhibition and
Medicinal Chemistry, DOI: 10.1080/14756366.2016.1201815
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J Enzyme Inhib Med Chem, Early Online: 1–7
2016 Informa UK Limited, trading as Taylor & Francis Group. DOI: 10.1080/14756366.2016.1201815
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RESEARCH ARTICLE
Synthesis, cyclooxygenase inhibition, anti-inflammatory evaluation and
ulcerogenic liability of new 1,5-diarylpyrazole derivatives
Khaled R. A. Abdellatif1, Wael A. A. Fadaly1, Waleed A. M. Ali2, and Gehan M. Kamel3
1Department of Pharmaceutical Organic Chemistry, Beni-Suef University, Beni-Suef, Egypt, 2Biochemistry Department, Cairo General Hospital, Cairo,
3
Egypt, and Pharmacology Department, Faculty of Veterinary, Cairo University, Cairo, Egypt
Abstract
Keywords
A new series of 1,5-diarylpyrazoles 10a–l was designed and synthesized for evaluation as COX
inhibitors and as anti-inflammatory agents. All compounds were more selective for COX-2
isozyme and showed good in vivo anti-inflammatory activity. Compound 10e was the most
COX-2 selective compound (S.I. ¼ 10.67) and the most potent anti-inflammatory derivative
(ED50 ¼ 46 mmol/kg) which is approximately 11-folds more potent than ibuprofen
(ED50 ¼ 499 mmol/kg) and had 2/3 potency of celecoxib (ED50 ¼ 31 mmol/kg). All compounds
were less ulcerogenic (ulcer indexes ¼ 1.20–4.61) than ibuprofen (ulcer index ¼ 20.25) and
comparable to celecoxib (ulcer index ¼ 2.90).
Anti-inflammatory, cyclooxygenase-2
inhibitors, 1,5-diarylpyrazole
History
Received 11 May 2016
Revised 6 June 2016
Accepted 7 June 2016
Published online 9 August 2016
Introduction
designing and synthesis of new series of diarylpyrazolines 4, 5
and diarylpyrazoles 6, 7 of moderate COX-2 selectivity and
Inflammation is a multi-staged process whose critical phase is
thought to be driven by acutely released arachidonic acid and
its metabolites including prostaglandins1. Two cyclooxygenase
(COX) isozymes, COX-1 and COX-2 are known to catalyze the
rate limiting step of prostaglandin synthesis2. Non-steroidal
anti-inflammatory drugs (NSAIDs) have become the most
widely used pharmaceuticals for treatment of inflammation
and pain by blocking the action of both COX isoforms3. COX-2
is upregulated by inflammatory mediators and forms prosta-
glandins which intensify the inflammatory response while
COX-1 is the house keeping isozyme making prostaglandins
which are important for maintaining physiological functions in
the body4. Traditional NSAIDs as aspirin, ibuprofen and
indomethacin exert their anti-inflammatory (AI) effect through
inhibition of both COX-1 and COX-2 and in turn their use was
accompanied with adverse effects including gastric bleeding
and ulceration5. Thus, it was thought that selective COX-2
inhibitors would have reduced side effects with improved
gastric safety profile. Most of the selective COX-2 inhibitors
(Figure 1) (coxibs) are diarylheterocycles in which, two vicinal
(adjacent) aryl moieties are attached to a five-membered ring as
pyrazole in celecoxib (1)6, furanone in rofecoxib (2)7 or
isoxazole in valdecoxib (3)8. Also, one of the two aryl rings is
substituted at para position with one COX-2 pharmacophoric
moiety either sulfamoyl (SO2NH2) or methanesulfonyl
(SO2CH3) moiety9,10. Realization about the importance of
COX-2 selective inhibitors for decreasing side effects associated
with nonselective COX inhibitors has stimulated our group for
good safety profile11–13
.
Based on the aforementioned information, we now describe the
synthesis, in vitro evaluation as COX-1/COX-2 inhibitors, in vivo
AI activity and ulcerogenic liability for a new series of
diarylpyrazoles 10a–l which maintains the vicinal diarylhetero-
cycle scaffold and is closely related to the structure of celecoxib
(1) but with three modifications: (i) the tolyl moiety of celecoxib
was replaced with electron withdrawing moieties as (4-bromo-
phenyl in 10a–c, 4-nitrophenyl in 10d–f or 4-chlorophenyl in
10g–i) or replaced with another electron donating moiety (2-
thienyl in 10j–l) to check the effect of these substituents on the
biological activity, (ii) trifluoromethyl moiety at C-3 of the
central five-membered pyrazole ring was removed since it was
reported that the substituent at C-3 of the central ring has very few
steric restrictions with respect to COX-2 binding14 and (iii) The
COX-2 pharmacophore SO2NH2 was maintained (10a, 10d, 10g
and 10j), replaced with another COX-2 pharmacophore SO2CH3
(10b, 10e, 10h and 10k) or replaced with COOH (10c, 10f, 10i
and 10l) (Figure 2).
Results and discussion
Chemistry
The enaminone derivatives (8a–d) were prepared via condensa-
tion of the appropriate aryl or heteroaryl methyl ketone with
dimethylformamide dimethylacetal (DMFDMA) in xylene fol-
lowing procedures applied in literatures15–21. Cyclocondensation
of the appropriate enaminone (8a–d) with 4-hydrazinylbenzene-
sulfonamide hydrochloride (9a)22, methanesulfonylphenylhydra-
zine hydrochloride (9b)23,24 or 4-hydrazinobenzoic acid (9c)25 in
aqueous ethanol afforded the respective 1,5-diarylpyrazoles
(10a–l) in good yields (56–88%) (Scheme 1).
Address for correspondence: Khaled R. A. Abdellatif, Ph.D., Department
of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Beni-Suef
University, Beni-Suef 62514, Egypt. Tel: +002 0100 2535444. Fax: +002
082 2317958. E-mail: khaled.ahmed@pharm.bsu.edu.eg

2
K. R. A. Abdellatif et al.
J Enzyme Inhib Med Chem, Early Online: 1–7
Me
SO2NH2
SO2Me
SO2NH2
N
O
N
O
O
N
Me
F3C
Celecoxib (1)
Rofecoxib (2)
Valdecoxib (3)
R2
R1
Ar
O
X
F
R3
N
N
N
NH
H3C
OH
R1 = H, OMe; R2 =H, OMe; R3 = H, OMe, SMe
Ar = 3-pyridyl, 4-pyridyl; X = O, S
(5)
(4)
F3C
HOOC
X
X
N
N
N
N
X= O,S
SO2R
X= O,S
SO2R
R = CH3, NH2
R = CH3, NH2
(6)
(7)
Figure 1. Chemical structures of the selective cyclooxygenase-2 inhibitors celecoxib (1), rofecoxib (2), valdecoxib (3), diarylpyrazoline derivatives
(4, 5) and the diarylpyrazoles (6, 7).
Figure 2. Chemical structures of the selective
cyclooxygenase-2 inhibitor celecoxib (1) and
the designed dihydropyrazoles 10a–l.
Br
NO2
H
H
N
N
N
N
R
R
10a-c
10d-f
CH3
F3C
N
N
SO2NH2
Celecoxib (1)
Cl
S
H
N
H
N
N
N
R
R
10j-l
10g-i
R = SO2NH2, SO2CH3, COOH

DOI: 10.1080/14756366.2016.1201815
Synthesis, cyclooxygenase inhibition, anti-inflammatory evaluation and ulcerogenic liability
3
R
NHNH2.HCl
O
a
Ar
N
+
N
N
8a-d
Ar
10a-l
R
8a; Ar = 4-BrC6H4,
8b; Ar = 4-NO2C6H4,
8c; Ar = 4-ClC6H4,
8d; Ar = 2-thienyl
9a-c
9a; R = SO2NH2,
9b; R = SO2CH3,
9c; R = COOH
10a; R = SO2NH2, Ar = 4-BrC6H4,
10b; R = SO2CH3, Ar = 4-BrC6H4,
10c; R = COOH, Ar = 4-BrC6H4,
10d; R = SO2NH2, Ar = 4-NO2C6H4,
10e; R = SO2CH3, Ar = 4-NO2C6H4,
10f; R = COOH, Ar = 4-NO2C6H4,
10g; R = SO2NH2, Ar = 4-ClC6H4,
10h; R = SO2CH3, Ar = 4-ClC6H4,
10i; R = COOH, Ar = 4-ClC6H4,
10j; R = SO2NH2, Ar = 2-thienyl,
10k; R = SO2CH3, Ar = 2-thienyl,
10l; R = COOH, Ar = 2-thienyl
Scheme 1. Reagents and conditions: (a) EtOH (95%), reflux, 36 h.
Biological evaluation
determined in comparison to the reference drugs celecoxib and
ibuprofen28. The tested diarylpyrazoles (10a–l) exhibited a broad
AI activity range (ED50 ¼ 46–878 mmol/kg) in comparison with
In vitro cyclooxygenase inhibition assay
The in vitro COX-1/COX-2 isozyme inhibition studies measure reference drugs celecoxib (ED50 ¼ 31 mmol/kg) and ibuprofen
the ability of tested compounds to inhibit ovine COX-1 and (ED50 ¼ 499 mmol/kg). Similar to the in vitro results, while the 4-
human recombinant COX-2 using an enzyme immunoassay nitrophenyl analogs (10d–f) had the highest AI activities
(EIA)26. The results (Table 1) showed that all the (ED50 ¼ 46–148 mmol/kg range), the other analogs (4-bromophe-
diarylpyrazoles (10a–l) are week inhibitors for COX-1 isozyme nyl analogs 10a–c, 4-chlorophenyl analogs 10g–i and 2-thienyl
(IC50 ¼ 2.91–10.21 mM range) and exhibited moderate COX-2 analogs 10j–l) had lower AI activities (ED50 ¼ 465–758, 503–737
isozyme inhibitory activities (IC50 ¼ 0.33–3.41 mM range) with and 305–878 mmol/kg ranges respectively). Also, within the all
COX-2 selectivity indexes in the range of 2.79–10.67. While the derivatives (10a–l), the 4-nitrophenyl-methanesulphonylphenyl
4-nitrophenyl analogs (10d–f) had the highest COX-2 potency derivative (10e), the most COX-2 selective derivative, was the
(IC50 ¼ 0.33–3.41 mM range) and the highest COX-2 selectivity most potent derivative (ED50 ¼ 46 mmol/kg) which is approxi-
indexes (S.I. ¼ 8.56–10.67), the other analogs (4-bromophenyl mately 11-folds more potent than ibuprofen (ED50 ¼ 499 mmol/kg)
analogs 10a–c, 4-chlorophenyl analogs 10g–i and 2-thienyl and 2/3 potency of celecoxib (ED50 ¼ 31 mmol/kg).
analogs 10j–l) had lower COX-2 potency (IC50 ¼ 1.43–2.89,
2.24–2.98 and 1.52–3.41 mM ranges respectively) and lower COX-
Ulcerogenic liability
2 selectivity indexes (S.I. ¼ 2.91–4.80, 2.79–3.42 and 2.84–3.93
The target compounds 10a–l were subjected to further study to
determine their ulcerogenic effect (ulcer index) using ED50 dose
in comparison with celecoxib (ED50 dose) and small dose of
Ibuprofen (120 mmol/kg)29. The results revealed that all com-
pounds 10a–l were less ulcerogenic (ulcer indexes ¼ 1.20–4.61)
than ibuprofen (ulcer index ¼ 20.25) and comparable to celecoxib
(ulcer index ¼ 2.90) (Table 2). Also, it was clear that, within each
group of analogs, the carboxylic derivative was more ulcerogenic
than the other derivatives which could be correlated to local
acidity effect of their carboxylic group. For 4-bromophenyl
analogs 10a–c, the carboxylic derivative 10c (ulcer index ¼ 4.61)
while the sulphamoyl derivative 10a and the methanesulphonyl
derivative 10b had ulcer indexes ¼ 2.92 and 2.68, respectively.
Similarly, within 4-nitrophenyl analogs 10d–f, 4-chlorophenyl
analogs 10g–i and 2-thienyl analogs 10j–l the carboxylic deriva-
ranges, respectively). Within the all derivatives (10a–l), the 4-
nitrophenylmethanesulphonylphenyl derivative (10e) had the
highest COX-2 selectivity index (S.I. ¼ 10.67) which is also
higher than that of the COX-2 selective reference drug celecoxib
(S.I. ¼ 9.29). Also, for each group of compounds; while the
COOH derivative (10c) was the most COX-2 selective
(S.I. ¼ 4.80) for the 4-bromophenyl analogs (10a–c) and the
SO2CH3 derivative (10e) was the most COX-2 selective
(S.I. ¼ 10.67) for the 4-nitrophenyl analogs (10d–f), the
SO2NH2 derivatives (10g, S.I. ¼ 3.42, 10j, S.I. ¼ 3.93) were the
most COX-2 selective derivatives for 4-chlorophenyl analogs
10g–i and 2-thienyl analogs 10j–l, respectively.
In vivo anti-inflammatory activity
The AI activities exhibited by the synthesized compounds were tives 10f, 10i and 10l (ulcer indexes ¼ 4.32, 4.36 and 3.89
determined using a carrageenan-induced rat paw edema model respectively) while the sulphamoyl derivatives 10d, 10g and 10j
and the dose causing 50% edema inhibition (ED50) was (ulcer indexes ¼ 1.20, 3.03 and 2.63, respectively) and the

4
K. R. A. Abdellatif et al.
J Enzyme Inhib Med Chem, Early Online: 1–7
Table 1. In vitro COX-1, COX-2 inhibition, anti-inflammatory activity of diarylpyrazoles (10a–l), and reference drugs celecoxib and ibuprofen.
R
N
N
Ar
1
R
10a-l
COX-1 IC50
(mM)a
COX-2 IC50
(mM)a
ED50
(mmol/kg)c
Compound
R
R1
Ar
COX-2 S.I.b
10a
10b
10c
10d
10e
10f
10g
10h
10i
10j
10k
10l
Celecoxib
Ibuprofend
SO2NH2
SO2CH3
COOH
SO2NH2
SO2CH3
COOH
SO2NH2
SO2CH3
COOH
SO2NH2
SO2CH3
COOH
SO2NH2
–
H
H
H
H
H
H
H
H
H
H
H
H
CF3
–
4-BrC6H4
4-BrC6H4
4-BrC6H4
4-NO2C6H4
4-NO2C6H4
4-NO2C6H4
4-ClC6H4
4-ClC6H4
4-ClC6H4
2-thienyl
2-thienyl
2-thienyl
4-CH3C6H4
–
7.52
8.42
6.87
3.51
5.87
2.91
7.67
8.11
8.34
5.98
9.23
10.21
7.34
2.9
2.33
2.89
1.43
0.41
0.55
0.33
2.24
2.63
2.98
1.52
3.25
3.41
0.79
1.1
3.22
2.91
4.80
8.56
10.67
8.81
3.42
3.08
2.79
3.93
2.84
2.99
9.29
2.64
465
604
758
145
46
148
525
737
503
878
305
537
31
499
aThe concentration of test compound produce 50% inhibition of COX-1, COX-2 enzyme, the result is the mean of two value obtained by assay of
enzyme kits obtained from (Cayman Chemicals Inc., Ann Arbor, MI).
bThe in vitro COX-2 selectivity index (COX-1/COX-2).
cInhibitory 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.
dData quoted from literature28
.
Table 2. Ulcerogenic liability for diarylpyrazoles (10a–l) and reference drugs celecoxib and ibuprofen.
Compound
Average severity
Average no. of ulcera
% incidence/10
Ulcer index
10a
10b
10c
10d
10e
10f
10g
10h
10i
10j
10k
10l
Celecoxib
Ibuprofen
0.73 0.017***,b
0.38 0.016***,b
1.2 0.037***,b
0.1 0.002***,b
0.28 0.015***,b
1.00 0.040b
0.83 0.030***
0.62 0.026***,b
0.85 0.035***,b
0.25 0.009***,b
0.17 0.004***,b
0.57 0.013***,b
0.5 0.013b
0.2 0.004***,b
0.3 0.001***,b
0.4 0.016***,b
0.1 0.003***,b
0.2 0.007b
2
2
3
1
2
3
2
2
3
2
2
3
2
10
2.92
2.68
4.61
1.2
2.47
4.32
3.03
3.02
4.36
2.63
2.66
3.89
2.9
0.3 0.008***,b
0.2 0.007***,b
0.4 0.015***,b
0.5 0.012,b
0.4 0.006,b
0.5 0.012***,b
0.3 0.004***,b
0.4 0.006b
2.25 0.13
8
20.25
***Significant difference with celecoxib at p50.001.
aValues represent means SEM of 10 animals for each group.
bSignificant difference with ibuprofen at p50.001.
methanesulphonyl derivatives 10e, 10h and 10k (ulcer indexes Conclusion
¼ 2.47, 3.02 and 2.66 respectively). The sulphamoyl derivative
A new series of 1,5-diarylpyrazoles 10a–l was synthesized for
evaluation as selective COX-2 inhibitors, AI agents and
ulcerogenic liability. Structure-activity data acquired and bio-
logical studies showed that (i) all compounds were more COX-2
10d was the most safe derivative (ulcer index ¼ 1.20) with relative
ulcerogenicities to the reference drugs celecoxib and ibuprofen
0.41 and 0.06, respectively.

DOI: 10.1080/14756366.2016.1201815
Synthesis, cyclooxygenase inhibition, anti-inflammatory evaluation and ulcerogenic liability
5
inhibitors than COX-1, (ii) the 4-nitrophenyl analogs (10d–f) had MS (m/z, relative abundance %): 377.26 (M+., 0.92); Anal. Calcd
higher AI activities than the other analogs (4-bromophenyl for C16H13BrN2O2S: C, 50.94; H, 3.47; N, 7.43; Found: C, 50.59;
analogs 10a–c, 4-chlorophenyl analogs 10g–i and 2-thienyl H, 3.35; N, 7.65.
analogs 10j–l), (iii) the 4-nitrophenyl-methanesulphonylphenyl
derivative (10e), the most COX-2 selective derivative, was the 4-[5-(4-Bromophenyl)pyrazol-1-yl]benzoic acid (10c)
most potent derivative which is approximately 11-folds more
56% yield; white solid; m.p. 205–207 ꢀC; IR (KBr disk) 3430
potent than ibuprofen (ED50 ¼ 499 mmol/kg) and 2/3 potency of
1
(OH), 1683 (C¼O) 1381, 1172 (SO2); H NMR (DMSO-d6) ꢀ
celecoxib (ED50 ¼ 31 mmol/kg), and (iv) all compounds were less
6.55 (d, J ¼ 1.6 Hz, 1H, pyrazole H-3), 7.19 (d, J ¼ 7.8 Hz, 2H,
ulcerogenic than ibuprofen and showed ulceration effect compar-
bromophenyl H-3, H-5), 7.35 (d, J ¼ 7.8 Hz, 2H, benzoic H-3, H-
able to that of celecoxib.
5), 7.42 (d, J ¼ 8.0 Hz, 2H, bromophenyl H-2, H-6), 7.80 (d,
J ¼ 1.6 Hz, 1H, pyrazole H-4), 8.10 (d, J ¼ 7.8 Hz, 2H, benzoic H-
Experimental
2, H-6), 13.11 (s, 1H, COOH, D2O exchangeable); 13C NMR
(DMSO-d6) ꢀ 109.07, 124.57, 128.05, 128.72, 128.98, 129.04,
129.80, 130.05, 130.47, 134.86, 141.07, 170.22; MS (m/z, relative
Chemistry
Melting points were determined on a Thomas-Hoover capillary abundance %): 343.17 (M+., 3.12); Anal. Calcd for
apparatus and are uncorrected. Infrared (IR) spectra were C16H11BrN2O2: C, 56.00; H, 3.23; N, 8.16; Found: C, 56.35; H,
recorded as films on KBr plates using a Nicolet 550 Series II 3.35; N, 7.95.
Magna FT-IR spectrometer. 1H NMR and 13C NMR spectra were
measured on a Bruker 400 MHz NMR Spectrophotometer,
4-[5-(4-Nitrophenyl)pyrazol-1-yl]benzenesulfonamide (10d)
Faculty of Pharmacy, Beni-Suef University, Egypt in CDCl3 or
88% yield; yellow solid; m.p. 255–257 ꢀC; IR (KBr disk) 3423,
3338 (NH2), 1339, 1165 (SO2); 1H NMR (DMSO-d6) ꢀ 6.87
DMSO-d6 with TMS as the internal standard, where J (coupling
constant) values are estimated in Hertz (Hz). Mass spectra (MS)
(d, J ¼ 1.6 Hz, 1H, pyrazole H-3), 7.50 (m, 2H, NH2, D2O
were recorded on a Water’s Micromass ZQ 4000 mass spectrom-
eter using the electro-spray (ES) ionization mode. Microanalyses
were performed for C, H and N were carried out on Perkin-Elmer
2400 analyzer (Perkin-Elmer, Norwalk, CT) at the micro analyt-
ical unit of Cairo University, Egypt. All compounds were within
0.4% of the theoretical values. Silica gel column chromatog-
raphy was performed using Merck silica gel 60 ASTM (70–230
mesh). Compounds 8a–d15–21, 9a–c22–25 were prepared according
to the reported procedures.
exchangeable and 2H, nitrophenyl H-3, H-5), 7.54 (d, J ¼ 8.0 Hz,
2H, aminosulfonylphenyl H-3, H-5), 7.79 (d, J ¼ 8.2 Hz, 2H,
nitrophenyl H-2, H-6), 7.92 (d, J ¼ 1.6 Hz, 1H, pyrazole H-4),
8.24 (d, J ¼ 8.0 Hz, 2H, aminosulfonylphenyl H-2, H-6); 13C
NMR (DMSO-d6) ꢀ 110.78, 124.40, 125.77, 127.37, 130.24,
136.53, 141.27, 141.85, 142.06, 143.55, 147.56; MS (m/z, relative
abundance %): 344.35 (M+., 9.34); Anal. Calcd for C15H12N4O4S:
C, 52.32; H, 3.51; N, 16.27; Found: C, 52.44; H, 3.35; N, 15.95.
1-(4-Methanesulfonylphenyl)-5-(4-nitrophenyl)-1H-pyrazole
(10e)
General method for preparation of diarylpyrazoles (10a–l)
A solution of the appropriate enaminone (8a–d, 0.1 mol) in ethanol
(50 mL) was heated under reflux with a mixture of p-substituted-
phenylhydrazine hydrochloride (9a–c, 0.1 mol) for 36 h, cooled
and diluted with cold water. The precipitated crude product was
filtered and recrystallized from ethanol to give the respective
pyrazoles (10a–l). Physical and spectral data are listed below.
74% yield; yellow solid; m.p. 222–224 ꢀC; IR (KBr disk) 1301,
1
1149 (SO2); H NMR (DMSO-d6) ꢀ 3.10 (s, 1H, SO2CH3), 6.59
(d, J ¼ 1.6 Hz, 1H, pyrazole H-3), 7.44 (d, J ¼ 8.2 Hz, 2H,
nitrophenyl H-3, H-5), 7.50 (d, J ¼ 8.2 Hz, 2H, methanesulfonyl-
phenyl H-3, H-5), 7.84 (d, J ¼ 1.6 Hz,1H, pyrazole H-4), 7.96 (d,
J ¼ 8.2 Hz, 2H, nitrophenyl H-3, H-5), 8.24 (d, J ¼ 8.2 Hz, 2H,
methanesulfonylphenyl H-2, H-6); 13C NMR (DMSO-d6) ꢀ 44.50,
110.57, 124.19, 125.31, 128.74, 129.48, 136.19, 139.54, 141.08,
141.87, 143.68, 144.14; MS (m/z, relative abundance %): 343.36
(M+., 35.57); Anal. Calcd for C16H13N3O4S: C, 55.97; H, 3.82; N,
12.24; Found: C, 55.61; H, 3.45; N, 11.95.
4-[5-(4-Bromophenyl)-pyrazol-1-yl]benzenesulfonamide (10a)
68% yield; white solid; m.p. 269–271 ꢀC; IR (KBr disk) 3375,
1
3202 (NH2), 1336, 1162 (SO2); H NMR (DMSO-d6) ꢀ 6.55 (d,
J ¼ 1.6 Hz, 1H, pyrazole H-3), 7.12 (d, J ¼ 8.0 Hz, 2H, bromo-
phenyl H-3, H-5), 7.28 (s, 2H, NH2, D2O exchangeable) 7.45 (d,
J ¼ 8.2 Hz, 2H, aminosulfonylphenyl H-3, H-5), 7.51 (d,
J ¼ 8.0 Hz, 2H, bromophenyl H-2, H-6), 7.78 (d, J ¼ 1.6 Hz, 1H,
pyrazole H-4), 7.91 (d, J ¼ 8.2 Hz, 2H, aminosulfonylphenyl H-2,
H-6); 13C NMR (DMSO-d6) ꢀ 109.33, 123.24, 124.57, 124.99,
127.54, 127.62, 128.96, 130.30, 131.25, 132.14, 143.17; MS (m/z,
relative abundance %): 378.24 (M+., 1.17); Anal. Calcd for
C15H12BrN3O2S: C, 47.63; H, 3.20; N, 11.11; Found: C, 47.35; H,
3.35; N, 11.35.
4-[5-(4-Nitrophenyl)pyrazol-1-yl]benzoic acid (10f)
69% yield; yellowish white solid; m.p. 256–258 ꢀC; IR (KBr disk)
3426 (OH), 1685 (C¼O) 1413, 1152 (SO2); 1H NMR (DMSO-d6)
ꢀ 6.92 (d, J ¼ 1.6 Hz, 1H pyrazole H-3), 7.41 (d, J ¼ 7.8 Hz, 2H,
nitrophenyl H-3, H-5), 7.52 (d, J ¼ 7.8 Hz, 2H, benzoic H-3, H-5),
7.91 (d, J ¼ 1.6 Hz, 1H, pyrazole H-4), 7.98 (d, J ¼ 7.8 Hz, 2H,
bromophenyl H-2, H-6), 8.12 (d, J ¼ 7.8 Hz, 2H, benzoic H-2, H-
6), 13.13 (s, 1H, COOH, D2O exchangeable); 13C NMR (DMSO-
d6) ꢀ 110.66, 124.36, 125.44, 125.52, 129.42, 130.14, 130.39,
130.77, 130.94, 136.54, 141.22, 167.00; MS (m/z, relative
abundance %): 309.01 (M+., 6.22); Anal. Calcd for
C16H11N3O4: C, 62.14; H, 3.58; N, 13.59; Found: C, 62.35; H,
3.35; N, 13.95.
5-(4-Bromophenyl)-1-(4-methanesulfonyl-phenyl)-1H-pyrazole
(10b)
72% yield; white solid; m.p. 241–243 ꢀC; IR (KBr disk) 1308,
1
1151 (SO2); H NMR (DMSO-d6) ꢀ 3.05 (s, 1H, SO2CH3), 6.56
(d, J ¼ 1.6 Hz, 1H, pyrazole H-3), 7.12 (d, J ¼ 8.0 Hz, 2H,
bromophenyl H-3, H-5), 7.51 (m, 4H, methanesulfonylphenyl H-
3, H-5 and bromophenyl H-3, H-5), 7.79 (d, J ¼ 1.6 Hz, 1H,
pyrazole H-4), 7.93 (d, J ¼ 8.2 Hz, 2H, methanesulfonylphenyl H-
2, H-6); 13C NMR (DMSO-d6) ꢀ 44.49, 109.53, 124.68, 125.11,
128.50, 128.58, 129.43, 130.05, 131.02, 135.16, 140.36, 141.60;
4-[5-(4-Chlorophenyl)pyrazol-1-yl]benzenesulfonamide (10g)
62% yield; white solid; m.p. 229–231 ꢀC; IR (KBr disk) 3346,
1
3194 (NH2), 1338, 1162 (SO2); H NMR (DMSO-d6) ꢀ 6.55 (d,
J ¼ 1.6 Hz, 1H, pyrazole H-3), 7.19 (d, J ¼ 8.2 Hz, 2H,

6
K. R. A. Abdellatif et al.
J Enzyme Inhib Med Chem, Early Online: 1–7
chlorophenyl H-3, H-5), 7.28 (s, 2H, NH2, D2O exchangeable), 304.09 (M+., 21.83); Anal. Calcd for C14H12N2O2S2: C, 55.24; H,
7.32 (d, J ¼ 8.0 Hz, 2H, aminosulfonylphenyl H-3, H-5), 7.41 (d, 3.97; N, 9.20; Found: C, 55.00; H, 3.71; N, 8.88.
J ¼ 8.2 Hz, 2H, chlorophenyl H-2, H-6), 7.79 (d, J ¼ 1.6 Hz, 1H,
pyrazole H-4), 8.09 (d, J ¼ 8.0 Hz, 2H, aminosulfonylphenyl H-2, 4-(5-Thiophen-2-yl-pyrazol-1-yl)benzoic acid (10l)
H-6); 13C NMR (DMSO-d6) ꢀ 109.34, 124.56, 125.01, 127.55,
72% yield; brown solid; m.p. 297–299 ꢀC; IR (KBr disk) 3428
127.62, 129.20, 129.37, 130.06, 131.04, 140.18, 141.39; MS (m/z,
1
(OH), 1693 (C¼O) 1347, 1173 (SO2); H NMR (DMSO-d6) ꢀ
6.67 (d, J ¼ 1.6 Hz, 1H, pyrazole H-3), 6.02 (s, 1H, thienyl H-4),
7.07 (s, 1H, thienyl H-5), 7.48 (d, J ¼ 7.6 Hz, 2H, benzoic H-3, H-
5), 7.62 (d, J ¼ 4.4 Hz, 1H, thienyl H-3), 7.81 (d, J ¼ 1.6 Hz, 1H,
pyrazole H-4), 8.05 (d, J ¼ 7.6 Hz, 2H, benzoic H-2, H-6), 13.19
(s, 1H, COOH, D2O exchangeable); 13C NMR (DMSO-d6) ꢀ
109.71, 125.49, 127.37, 127.42, 127.71, 128.11, 141.05, 141.28,
141.63, 145.00, 145.22, 169.81; MS (m/z, relative abundance %):
270.05 (M+., 3.18); Anal. Calcd for C14H10N2O2S: C, 62.21; H,
3.73; N, 10.36; Found: C, 62.35; H, 3.35; N, 9.95.
relative abundance %): 333.03 (M+., 70.42); Anal. Calcd for
C15H12ClN3O2S: C, 53.97; H, 3.62; N, 12.59; Found: C, 54.35; H,
3.35; N, 12.75.
5-(4-Chlorophenyl)-1-(4-methanesulfonylphenyl)-1H-pyrazole
(10h)
79% yield; yellow solid; m.p. 236–238 ꢀC; IR (KBr disk) 1305,
1
1150 (SO2); H NMR (DMSO-d6) ꢀ 3.09 (s, 1H, SO2CH3), 6.56
(d, J ¼ 1.6 Hz, 1H, pyrazole H-3), 7.19 (d, J ¼ 7.8 Hz, 2H,
chlorophenyl H-3, H-5), 7.36 (d, J ¼ 7.8 Hz, 2H, methanesulfo-
nylphenyl H-3, H-5), 7.51 (d, J ¼ 7.8 Hz, 2H, chlorophenyl H-3,
H-5), 7.79 (d, J ¼ 1.6 Hz, 1H, pyrazole H-4), 7.93 (d, J ¼ 7.8 Hz,
2H, methanesulfonylphenyl H-2, H-6); 13C NMR (DMSO-d6) ꢀ
44.53, 109.52, 123.32, 125.11, 128.50, 128.91, 130.29, 132.19,
138.94, 141.66, 142.32, 144.02; MS (m/z, relative abundance %):
332.04 (M+., 71.47); Anal. Calcd for C16H13ClN2O2S: C, 57.74;
H, 3.94; N, 8.42; Found: C, 57.39; H, 3.75; N, 8.15.
Biological evaluation
COX-1/COX-2 inhibition colorimetric assay
The ability of the test compounds listed in Table 1 to inhibit ovine
COX-1 and human recombinant COX-2 (IC50 value, mM) was
determined using an enzyme immuno assay (EIA) kit (catalog no.
560131, Cayman Chemical, Ann Arbor, MI) according to the
previously reported method26.
4-[5-(4-Chlorophenyl)pyrazol-1-yl]benzoic acid (10i)
In vivo anti-inflammatory activity
77% yield; yellowish white solid; m.p. 244–246 ꢀC; IR (KBr disk)
3431 (OH), 1684 (C¼O) 1381, 1174 (SO2); 1H NMR (DMSO-d6)
ꢀ 6.55 (d, J ¼ 1.6 Hz, 1H pyrazole H-3), 7.18 (d, J ¼ 8.0 Hz, 2H,
chlorophenyl H-3, H-5), 7.35 (d, J ¼ 7.8 Hz, 2H, benzoic H-3,
H-5), 7.45 (d, J ¼ 8.0 Hz, 2H, chlorophenyl H-2, H-6), 7.78 (d,
J ¼ 1.6 Hz, 1H, pyrazole H-4), 7.91 (d, J ¼ 8.0 Hz, 2H, benzoic H-
2, H-6), 13.11 (s, 1H, COOH, D2O exchangeable); 13C NMR
(DMSO-d6) ꢀ 109.08, 124.53, 124.57, 127.90, 128.71, 128.98,
129.04, 130.05, 134.87, 141.04, 143.94, 169.38; MS (m/z, relative
abundance %): 298.06 (M+., 100.00); Anal. Calcd for
C16H11ClN2O2: C, 64.33; H, 3.71; N, 9.38; Found: C, 64.35; H,
3.35; N, 8.95.
Animals
Adult male Wistar Albino rats (100–150 g) were used in the
pharmacological studies. The animals (five per cage) were
maintained under standard laboratory conditions (light period of
12 h/day and temperature 27 2 ꢀC), with access to food and
water. The experimental procedures were carried out in strict
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.
The dose causing 50% edema inhibition (ED50) for test
compounds 10a–l and reference drugs celecoxib and ibuprofen
were determined using the in vivo carrageenan-induced rat paw
edema model and the measurement of paw thickness was done at
3 h after oral administration of the test compound as reported
previously27.
4-(5-Thiophen-2-yl-pyrazol-1-yl)benzenesulfonamide (10j)
77% yield; brown solid; m.p. 258–260 ꢀC; IR (KBr disk) 3427,
1
3302 (NH2), 1341, 1160 (SO2); H NMR (DMSO-d6) ꢀ 6.61 (d,
J ¼ 1.6 Hz, 1H, pyrazole H-3), 6.90 (s, 1H, thienyl H-4), 7.03 (s,
1H, thienyl H-5), 7.28 (s, 2H, NH2, D2O exchangeable), 7.38 (d,
J ¼ 4.4 Hz, 1H, thienyl H-3), 7.56 (d, J ¼ 8.0 Hz, 2H, aminosulfo-
Ulcerogenic liability study
Ulcerogenic liability of the target compounds 10a–l were
nylphenyl H-3, H-5), 7.76 (d, J ¼ 1.6 Hz, 1H, pyrazole H-4), 7.95 determined using ED50 dose in comparison with celecoxib
(d, J ¼ 8.0 Hz, 2H, aminosulfonylphenyl H-2, H-6); 13C NMR (ED50 dose) and small dose of Ibuprofen (120 mmol/kg) according
to the previously reported method29.
(DMSO-d6) ꢀ 109.71, 125.49, 127.37, 127.42, 127.71, 128.11,
141.28, 141.63, 145.00, 145.22, 145.41; MS (m/z, relative
abundance %): 305.07 (M+., 6.32); Anal. Calcd for
C13H11N3O2S2: C, 51.13; H, 3.63; N, 13.76; Found: C, 51.35;
H, 3.35; N, 13.95.
Declaration of interest
The authors have declared no conflict of interest.
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