Synthesis, cyclooxygenase inhibition and anti-inflammatory evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives possessing methanesulphonyl pharmacophore

Article abstract of DOI:10.3109/14756366.2016.1158168

A new series of 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives 13a–p were synthesized via aldol condensation of 3/4-nitroacetophenones with appropriately substituted aldehydes followed by cyclization of the formed chalcones with 4-methanesulfonylphenylhydrazine hydrochloride. All the synthesized compounds were evaluated for their cyclooxygenase (COX) inhibition, anti-inflammatory activity and ulcerogenic liability. All compounds were more potent inhibitors for COX-2 than COX-1. While most compounds showed good anti-inflammatory activity, compounds 13d, 13f, 13k and 13o were the most potent derivatives (ED₅₀ = 66.5, 73.4, 79.8 and 70.5 μmol/kg, respectively) in comparison with celecoxib (ED₅₀ = 68.1 μmol/kg). Compounds 13d, 13f, 13k and 13o (ulcer index = 3.89, 4.86, 4.96 and 3.92, respectively) were 4–6 folds less ulcerogenic than aspirin (ulcer index = 22.75) and showed approximately ulceration effect similar to celecoxib (ulcer index = 3.35). In addition, molecular docking studies were performed for compounds 13d, 13f, 13k and 13o inside COX-2 active site which showed acceptable binding interactions (affinity in kcal/mol ?2.1774, ?6.9498) in comparison with celecoxib (affinity in kcal/mol ?6.5330).

Full text of DOI:10.3109/14756366.2016.1158168

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 and anti-
inflammatory evaluation of new 1,3,5-triaryl-4,5-
dihydro-1H-pyrazole derivatives possessing
methanesulphonyl pharmacophore
Khaled R. A. Abdellatif, Mohammed T. Elsaady, Salah A. Abdel-Aziz & Ahmed
H. A. Abusabaa
To cite this article: Khaled R. A. Abdellatif, Mohammed T. Elsaady, Salah A. Abdel-
Aziz & Ahmed H. A. Abusabaa (2016): Synthesis, cyclooxygenase inhibition and anti-
inflammatory evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives possessing
methanesulphonyl pharmacophore, Journal of Enzyme Inhibition and Medicinal Chemistry,
DOI: 10.3109/14756366.2016.1158168
To link to this article: http://dx.doi.org/10.3109/14756366.2016.1158168
Published online: 12 Apr 2016.
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ISSN: 1475-6366 (print), 1475-6374 (electronic)
J Enzyme Inhib Med Chem, Early Online: 1–11
2016 Taylor & Francis. DOI: 10.3109/14756366.2016.1158168
!
RESEARCH ARTICLE
Synthesis, cyclooxygenase inhibition and anti-inflammatory evaluation
of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives possessing
methanesulphonyl pharmacophore
Khaled R. A. Abdellatif1, Mohammed T. Elsaady2, Salah A. Abdel-Aziz3, and Ahmed H. A. Abusabaa3
2
1Department of Pharmaceutical Organic Chemistry, Beni-Suef University, Beni-Suef, Egypt, Department of Medicinal Chemistry, Beni-Suef
3
University, Beni-Suef, Egypt, and Department of Pharmaceutical Medicinal Chemistry, Al-Azhar University, Assuit, Egypt
Abstract
Keywords
A new series of 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives 13a–p were synthesized via
aldol condensation of 3/4-nitroacetophenones with appropriately substituted aldehydes
followed by cyclization of the formed chalcones with 4-methanesulfonylphenylhydrazine
hydrochloride. All the synthesized compounds were evaluated for their cyclooxygenase (COX)
inhibition, anti-inflammatory activity and ulcerogenic liability. All compounds were more
potent inhibitors for COX-2 than COX-1. While most compounds showed good anti-
inflammatory activity, compounds 13d, 13f, 13k and 13o were the most potent derivatives
(ED50 ¼ 66.5, 73.4, 79.8 and 70.5 mmol/kg, respectively) in comparison with celecoxib
(ED50 ¼ 68.1 mmol/kg). Compounds 13d, 13f, 13k and 13o (ulcer index ¼ 3.89, 4.86, 4.96 and
3.92, respectively) were 4–6 folds less ulcerogenic than aspirin (ulcer index ¼ 22.75) and showed
approximately ulceration effect similar to celecoxib (ulcer index ¼ 3.35). In addition, molecular
docking studies were performed for compounds 13d, 13f, 13k and 13o inside COX-2 active site
which showed acceptable binding interactions (affinity in kcal/mol ꢀ2.1774, ꢀ6.9498) in
comparison with celecoxib (affinity in kcal/mol ꢀ6.5330).
Anti-inflammatory, cyclooxygenase inhibition,
dihydropyrazole
History
Received 1 November 2015
Revised 7 February 2016
Accepted 9 February 2016
Published online 12 April 2016
Introduction
the only and highly marketed coxib, so, there is still a need for
synthesis of COX-2 inhibitor with no adverse effects (Figure 2).
We have previously reported6–11 some derivatives of celecoxib
(4–8) which showed considerable anti-inflammatory activity.
In continuation of our previous work for development of safe
anti-inflammatory derivatives, we now describe the synthesis,
in vitro evaluation as COX-1/COX-2 inhibitors, in vivo anti-
inflammatory (AI) activity and ulcerogenic liability for a new
series of 1,3,5-triaryl-4,5-dihydro-1H-pyrazoles 13a–p as cele-
coxib derivatives in which; (i) pyrazole ring of celecoxib was
replaced with 4,5-dihydropyrazole nucleus, (ii) trifluoromethyl
moiety was replaced with substituted aryl moiety; it was reported
that the substituent at pyrazole C-3 has little steric restrictions for
COX-2, and observed that COX-2 inhibition should be
remained12, (iii) tolyl group was maintained or replaced with
different substituted aryl or heteroaryl moieties and (iv) the COX-
2 pharmacophore (sulphamoyl, SO2NH2) group on the N1-phenyl
ring was replaced with another COX-2 pharmacophoric moiety
(methanesulfonyl, SO2CH3).
Traditional non-steroidal anti-inflammatory drugs (NSAIDs)
reduce the pain and inflammation through inhibition of both
cyclooxygenase-1 and -2 (COX-1 and COX-2)1. While COX-1
enzyme is constitutively expressed and plays an important role as
a housekeeping enzyme such as protection of gastric mucosa,
vascular homeostasis and platelet aggregation, COX-2 enzyme is
expressed and significantly upregulated during acute and chronic
inflammation, pain and oncogenesis2. Non-selective NSAIDs
such as aspirin, ibuprofen and indomethacin inhibit the activities
of both enzymes and in turn inhibit the production of gastro
protective prostaglandins (PGs) synthesized through COX-1
pathway causing gastro intestinal side effects like ulcers, perfor-
ation and bleeding3. For this reason, selective COX-2 inhibitor
drugs (coxibs) such as celecoxib (1), rofecoxib (2) and valdecoxib
(3) (Figure 1) which have the same anti-inflammatory efficacy as
traditional NSAIDs with minimized unwanted gastrointestinal
side effects take much consideration in the last two decades4.
Unfortunately, highly selective COX-2 inhibitors caused cardio-
vascular side effects such as increased systemic blood pressure
and myocardial infarction that ultimately prompted the with-
drawal of rofecoxib and valdecoxib5. At present, celecoxib (1) is
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 and 13C NMR spectra
were measured on a Bruker 400 MHz spectrometer (Faculty of
Pharmacy, Beni-Suef University, Beni-Suef, Egypt) in D2O,
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: 1–11
Me
SO2NH2
SO2Me
SO2NH2
N
O
N
O
O
N
Me
Celecoxib (1)
F3C
Rofecoxib (2)
NHR1
Valdecoxib (3)
R
H
N
SO2Me
SO2R2
SO2R
N
N
N
N
N
N
HOOC
R = H, F, Me
(4)
R1 = Me, Et; R2 = Me, NH2
F3C
R = Me, NH2
(6)
F3C
(5)
H3CO2S
R2
Ar
R1
F
N
N
R3
N
NH
OH
SO2NH2
R1 = H, OMe; R 2 =H, OMe; R 3 = H, OMe, SMe
Ar = 4-FC 6H4, 3,4,5-(OCH 3)3C6H2
(8)
(7)
Figure 1. Chemical structures of the selective cyclooxygenase-2 (COX-2) inhibitors celecoxib (1), rofecoxib (2) and valdecoxib (3), and celecoxib
analogs (4–8).
CH3
Figure 2. Chemical structures of the selective
cyclooxygenase-2 (COX-2) inhibitor cele-
coxib (1) and the designed 1,3,5-triaryldihy-
dropyrazoles 13a–p.
4
Ar
5
3
4
5
1
3
N
R
F3C
N
1
N
2
N
2
SO2CH3
13a-p
SO2NH2
Celecoxib (1)
R = 3-NO2, 4-NO2
Ar = C6H5, 4-CH3C6H4, 4-FC6H4, 2-ClC6H4,
4-ClC6H4, 4-OCH3C6H4, 4-N(CH3)2C6H3, 2-furyl
DMSO-d6 with TMS as the internal standard, where J (coupling CH¼CH, J ¼ 15.5 Hz), 8.02–7.95 (m, 3H, Ar–H and CH¼CH),
constant) values were estimated in hertz (Hz). Mass spectra were 8.38 (s, 4H, Ar–H).
run on Hewlett Packard 5988 spectrometer. Microanalysis was
performed for C, H, N at the Micro Analytical Center, Cairo
3-(4-Fluorophenyl)-1-(4-nitrophenyl)prop-2-en-1-one (11c)
University, Egypt and was within 0.4% of theoretical values. All
IR (KBr disk) 1609 (Ar–C¼C), 1H NMR (DMSO-d6)
other reagents, purchased from the Acros Chemical Company
(Milwaukee, WI), were used without further purification.
7.36–7.30 (m, 2H, Ar–H), 7.83 (s, 1H, CH¼CH), 7.90 (s,
Chalcones 11a13, 11b–d14, 11e15, 11f14 11 g16, 11 h17, 11i–j18,
1H, CH¼CH), 8.03–8.00 (m, 2H, Ar–H), 8.40–8.33 (m, 4H,
11k19, 11l20, 11m21, 11n18, 11o22, 11p23 and 4-methanesulfonyl-
phenylhydrazine hydrochloride (12)24 were prepared according to
reported procedures.
Ar–H).
3-(4-(Dimethylamino) phenyl)-1-(4-nitrophenyl)prop-2-en-1-one
(11d)
Spectral data (14) for chalcones 11b, 11c, 11d and 11f are
listed below
IR (KBr disk) 3047 (C–H), 2909 (C–H), 1653 (C¼O),
1598 (Ar–C¼C), 3.02 (s, 6H, N(CH3)2, 6.77–6.74 (d, 2H,
Ar–H, J ¼ 8.7 Hz), 7.64–7.60 (d, 1H, CH¼CH, J ¼ 11.7 Hz),
3-(4-Chlorophenyl)-1-(4-nitrophenyl)prop-2-en-1-one (11b)
IR (KBr disk) 3097(CH), 1662 (C¼O), 1606 (Ar–C¼C); 1H NMR 7.75–7.71 (m, 3H, Ar–H and CH¼CH), 8.36–8.28 (m, 4H,
(DMSO-d6) ꢀ 7.57–7.54 (m, 2H, Ar–H), 7.83–7.77 (d, 1H, Ar–H).

DOI: 10.3109/14756366.2016.1158168
1,3,5-Triaryl-4,5-dihydro-1H-pyrazole derivatives
3
3-(4-Methoxyphenyl)-1-(4-nitrophenyl)prop-2-en-1-one (11f)
(d, J ¼ 5.2 Hz, 2H, methanesulphonylphenyl H-2, H-6), 7.72
(d, J ¼ 8.8 Hz, 2H, methanesulphonylphenyl H-3, H-5), 8.03
(d, J ¼ 8.8 Hz, 2H, nitrophenyl H-2, H-6), 8.29 (d, J ¼ 8.8 Hz, 2H,
nitrophenyl H-3, H-5); 13C NMR (DMSO-d6) ꢀ 43.18 (pyrazole
C-4), 44.86 (SO2CH3), 63.48 (pyrazole C-5), 113.3, 116.75,
124.10, 126.54, 127.35, 129.00, 130.66, 136.19, 137.82, 146.96,
147.15, 147.86, 162.62 (d, J ¼ 247 Hz, C-F); MS (m/z): 439 (M+.,
99.21%); Anal. Calcd. for C22H18N3O4SF: C, 60.13; H, 4.13; N,
9.56. Found: C, 60.41; H, 4.17; N, 9.64.
1
IR (KBr disk) 1655 (C¼O), 1595 (Ar–C¼C); H NMR (DMSO-
d6) ꢀ 3.83 (s, 3H, OCH3), 7.03 (d, 2H, Ar–H, J ¼ 6 Hz),7.77
(d, 2H, Ar–H, J ¼ 12 Hz), 7.86 (d, 2H, CH¼CH, J ¼ 16.5 Hz),
8.38–8.29 (m, 4H, Ar–H).
General procedure for preparation of 1,3,5-triaryl-4,5-
dihydro-1H-pyrazoles (13a–p)
To a solution of the appropriate chalcone 11a–p (2.0 mmol) in
ethanol (20 mL), 4-methanesulfonylphenylhydrazine hydrochlor- 5-(4-Dimethylaminophenyl)-1-(4-methanesulfonylphenyl)-3-(4-
ide (12, 3.0 mmol, 0.666 g) was added and the reaction mixture nitrophenyl)-4,5-dihydro-1H-pyrazole (13d)
was heated under reflux for 12–18 h. The reaction was monitored
Yield: 60%; red crystals; m.p. 162–165 ꢁC; IR (KBr disk) 2918
every 60 min interval on TLC plates using chloroform/methanol
1
(C–H aliphatic), 1334, 1136 (SO2); H NMR (DMSO-d6) ꢀ 2.96
(9.5:0.5 V/V). After completion of the reaction, the mixture was
(s, 6H, N(CH3)2), 3.10 (s, 3H, SO2CH3), 3.26 (dd, J ¼ 17.6,
poured into ice cold water. The obtained solid was filtered,
5.6 Hz, 1H, pyrazole H-4), 4.04 (dd, J ¼ 17.6, 12.0 Hz, 1H,
washed with water, dried and crystallized from ethyl acetate to
pyrazole H0-4), 5.77 (dd, J ¼ 12.0, 5.6 Hz, 1H, pyrazole H-5), 7.11
give the respective triarylpyrazoles 13a–p. Physical and spectral
(d, J ¼ 8.4 Hz, 2H, dimethylaminophenyl H-3, H-5), 7.23 (d,
data for 13a–p are listed below.
J ¼ 8.8 Hz, 2H, dimethylaminophenyl H-2, H-6), 7.72
(d, J ¼ 8.8 Hz, 2H, methanesulphonylphenyl H-2, H-6), 7.81
1-(4-Methanesulfonylphenyl)-3-(4-nitrophenyl)-5-phenyl-4,5-
(d, J ¼ 8.8 Hz, 2H, methanesulphonylphenyl H-3, H-5), 8.04 (d,
dihydro-1H-pyrazole (13a)
J ¼ 8.8 Hz, 2H, nitrophenyl H-2, H-6), 8.30 (d, J ¼ 8.8 Hz, 2H,
Yield: 58%; orange powder; m.p. 118–120 ꢁC; IR (KBr disk) 2923 nitrophenyl H-3, H-5); 13C NMR (DMSO-d6) ꢀ 43.13 (pyrazole
(C–H aliphatic), 1322, 1136 (SO2); H NMR (DMSO-d6) ꢀ 3.09 C-4), 44.89 (SO2CH3), 50.88 (N(CH3)2), 63.8 (pyrazole C-5),
1
(s, 3H, SO2CH3), 3.29 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4), 113.30, 124.06, 124.57, 126.44, 126.62, 128.90, 129.03, 129.29,
4.06 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.79 (dd, J ¼ 12.0, 129.73, 130.04, 138.20, 147.22, 147.65; MS (m/z): 464 (M+.,
5.6 Hz, 1H, pyrazole H-5), 7.22 (d, J ¼ 8.8 Hz, 2H, phenyl H-3, 42.01%); Anal. Calcd. for C24H24N4O4S: C, 62.05; H, 5.21; N,
H-5), 7.27–7.30 (m, 3H, phenyl H-2, H-6, H-4), 7.37 (d, 12.06. Found: C, 62.17; H, 5.29; N, 12.31.
J ¼ 7.2 Hz, 2H, methanesulphonylphenyl H-2, H-6), 7.75
(d, J ¼ 8.8 Hz, 2H, methanesulphonylphenyl H-3, H-5), 7.96
1-(4-Methanesulfonylphenyl)-5-(4-methylphenyl)-3-(4-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13e)
(d, J ¼ 8.8 Hz, 2H, nitrophenyl H-2, H-6), 8.30 (d, J ¼ 9.2 Hz, 2H,
nitrophenyl H-3, H-5); 13C NMR (DMSO-d6) ꢀ 43.15 (pyrazole
C-4), 44.88 (SO2CH3), 64.12 (pyrazole C-5), 113.28, 124.08,
125.51, 126.52, 128.44, 128.97, 129.74, 130.34, 137.97, 140.39,
147.08, 147.19, 147.75; MS (m/z): 421 (M+., 5.10%); Anal. Calcd.
for C22H19N3O4S: C, 62.69; H, 4.54; N, 9.97. Found: C, 62.81; H,
4.60; N, 10.12.
Yield: 45%; orange powder; m.p. 214–216 ꢁC; IR (KBr disk) 2976
1
(C–H aliphatic), 1328, 1135 (SO2); H NMR (DMSO-d6) ꢀ 2.25
(s, 3H, CH3), 3.09 (s, 3H, SO2CH3), 3.25 (dd, J ¼ 17.6, 5.6 Hz,
1H, pyrazole H-4), 4.03 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole
H0-4), 5.74 (dd, J ¼ 12.0, 5.6 Hz, 1H, pyrazole H-5), 7.15 (s, 4H,
methylphenyl H-2, H-6, H-3, H-5), 7.22 (d, J ¼ 8.4 Hz,
2H, methanesulphonylphenyl H-2, H-6), 7.71 (d, J ¼ 8.8 Hz,
5-(4-Chlorophenyl)-1-(4-methanesulfonylphenyl)-3-(4-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13b)
2H, methanesulphonylphenyl H-3, H-5), 8.04 (d, J ¼ 8.8 Hz, 2H,
nitrophenyl H-2, H-6), 8.30 (d, J ¼ 8.8 Hz, 2H, nitrophenyl H-3,
H-5); 13C NMR (DMSO-d6) ꢀ 21.10 (CH3), 43.03 (pyrazole C-4),
44.50 (SO2CH3), 63.18 (pyrazole C-5), 113.29, 124.48, 126.14,
127.46, 129.06, 130.26, 130.61, 137.63, 138.40, 138.60, 146.89,
147.62, 148.93; MS (m/z): 435 (M+., 72.10%); Anal. Calcd. for
C23H21N3O4S: C, 63.43; H, 4.86; N, 9.65. Found: C, 63.60; H,
4.94; N, 9.78.
Yield: 63%; orange powder; m.p. 264–266 ꢁC; IR (KBr disk) 2924
1
(C–H aliphatic), 1331, 1137 (SO2); H NMR (DMSO-d6) ꢀ 3.10
(s, 3H, SO2CH3), 3.30 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4),
4.05 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.81 (dd, J ¼ 12.0,
5.6 Hz, 1H, pyrazole H-5), 7.21 (d, J ¼ 8.8 Hz, 2H, chlorophenyl
H-2, H-6), 7.32 (d, J ¼ 8.4 Hz, 2H, chlorophenyl H-3, H-5), 7.44
(d, J ¼ 8.4 Hz, 2H, methanesulphonylphenyl H-2, H-6), 7.72 (d,
J ¼ 8.4 Hz, 2H, methanesulphonylphenyl H-3, H-5), 8.03 (d,
J ¼ 8.4 Hz, 2H, nitrophenyl H-2, H-6), 8.30 (d, J ¼ 8.4 Hz, 2H,
nitrophenyl H-3, H-5); 13C NMR (DMSO-d6) ꢀ 42.86 (pyrazole
C-4), 44.51 (SO2CH3), 62.69 (pyrazole C-5), 113.31, 124.46,
127.54, 128.26, 129.15, 129.71, 130.90, 132.89, 138.26, 140.49,
146.77, 147.72, 149.04; MS (m/z): 455 (M+., 77.15%); Anal.
Calcd. for C22H18N3O4SCl: C, 57.96; H, 3.98; N, 9.22. Found: C,
57.9; H, 3.93; N, 9.35.
1-(4-Methanesulfonylphenyl)-5-(4-methoxyphenyl)-3-(4-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13f)
Yield: 55%; orange powder; m.p. 212–214 ꢁC; IR (KBr disk) 2921
1
(C–H aliphatic), 1332, 1138 (SO2); H NMR (DMSO-d6) ꢀ 3.00
(s, 3H, SO2CH3), 3.79 (s, 3H, OCH3), 3.23 (dd, J ¼ 17.6, 5.6 Hz,
1H, pyrazole H-4), 3.93 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole
H0-4), 5.46 (dd, J ¼ 12.0, 5.6 Hz, 1H, pyrazole H-5), 6.89 (d,
J ¼ 8.0 Hz, 2H, methoxyphenyl H-2, H-6), 7.18 (d, J ¼ 7.6 Hz,
4H, methoxyphenyl H-3, H-5 and methanesulphonylphenyl H-2,
H-6), 7.71 (d, J ¼ 8.4 Hz, 2H, methanesulphonylphenyl H-3, H-5),
7.88 (d, J ¼ 8.4 Hz, 2H, nitrophenyl H-2, H-6), 8.24 (d,
J ¼ 8.4 Hz, 2H, nitrophenyl H-3, H-5); 13C NMR (DMSO-d6) ꢀ
43.19 (pyrazole C-4), 44.89 (SO2CH3), 55.34 (OCH3), 63.69
(pyrazole C-5), 113.31, 114.92, 124.07, 126.49, 126.80, 128.91,
130.26, 132.39, 138.09, 147.13, 147.22, 147.71, 159.55; MS
(m/z): 451 (M+., 100%); Anal. Calcd. for C23H21N3O5S: C, 61.18;
H, 4.69; N, 9.31. Found: C, 61.42; H, 4.78; N, 9.47.
5-(4-Flourophenyl)-1-(4-methanesulfonylphenyl)-3-(4-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13c)
Yield: 71%; orange powder; m.p. 226–228 ꢁC; IR (KBr disk) 2927
1
(C–H aliphatic), 1336, 1140 (SO2); H NMR (DMSO-d6) ꢀ 3.10
(s, 3H, SO2CH3), 3.29 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4),
4.03 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.82 (dd, J ¼ 12.0,
5.6 Hz, 1H, pyrazole H-5), 7.17–7.21 (m, 2H, flourophenyl H-2,
H-6), 7.21 (d, J ¼ 6.8 Hz, 2H, flourophenyl H-3, H-5), 7.33

4
K. R. A. Abdellatif et al
J Enzyme Inhib Med Chem, Early Online: 1–11
5-(2-Chlorophenyl)-1-(4-methanesulfonyl-phenyl)-3-(4-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13g)
(d, J ¼ 8.4 Hz, 2H, methanesulphonylphenyl H-2, H-6), 7.72
(d, J ¼ 9.2 Hz, 2H, methanesulphonylphenyl H-3, H-5), 7.77 (t,
J ¼8.0 1H, nitrophenyl H-5), 8.20 (d, J ¼ 8.0 Hz, 1H, nitrophenyl
H-6), 8.27 (d, J ¼ 8 Hz, 1H, nitrophenyl H-4), 8.54 (s, 1H,
nitrophenyl H-2); 13C NMR (DMSO-d6) ꢀ 43.03 (pyrazole C-4),
44.56 (SO2CH3), 62.47 (pyrazole C-5), 113.07, 120.72, 124.17,
128.28, 129.15, 129.66, 130.49, 130.91, 132.83, 133.69, 140.56,
147.01, 148.65, 149.25; MS (m/z): 455 (M+., 24.53%); Anal.
Calcd. for C22H18N3O4SCl: C, 57.96; H, 3.98; N, 9.22. Found: C,
57.85; H, 3.86; N, 9.22.
Yield: 71%; orange powder; m.p. 220–222 ꢁC; IR (KBr disk) 2918
1
(C–H aliphatic), 1339, 1139 (SO2); H NMR (DMSO-d6) ꢀ 3.11
(s, 3H, SO2CH3), 3.28 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4),
4.14 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.94 (dd, J ¼ 12.0,
5.6 Hz, 1H, pyrazole H-5), 7.01–7.13 (m, 3H, chlorophenyl H-4,
H-5, H-6), 7.37 (d, J ¼ 6.8 Hz, 2H, methanesulphonylphenyl H-2,
H-6), 7.60 (s, 1H, chlorophenyl H-3), 7.75 (d, J ¼ 9.2 Hz, 2H,
methanesulphonylphenyl H-3, H-5), 8.04 (d, J ¼ 8.8 Hz, 2H,
nitrophenyl H-2, H-6), 8.29 (d, J ¼ 8.8 Hz, 2H, nitrophenyl H-3,
H-5); 13C NMR (DMSO-d6) ꢀ 41.77 (pyrazole C-4), 44.87 5-(4-Flourophenyl)-1-(4-methanesulfonyl-phenyl)-3-(3-nitrophe-
(SO2CH3), 61.06 (pyrazole C-5), 113.18, 124.08, 126.59, 127.93, nyl)-4,5-dihydro-1H-pyrazole (13k)
129.11, 129.66, 130.44, 130.67, 131.78, 137.05, 137.80, 146.81,
Yield: 65%; yellow powder; m.p. 192–194 ꢁC; IR (KBr disk) 2923
147.69, 147.86; MS (m/z): 455 (M+., 24.27%); Anal. Calcd. for
1
(C–H aliphatic), 1347, 1136 (SO2); H NMR (DMSO-d6) ꢀ 3.09
C22H18N3O4SCl: C, 57.96; H, 3.98; N, 9.22. Found: C, 57.92; H,
(s, 3H, SO2CH3), 3.29 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4),
4.05; N, 9.40.
4.06 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.78 (dd, J ¼ 12.0,
5.6 Hz, 1H, pyrazole H-5), 7.16–7.20 (m, 2H, flourophenyl H-2,
H-6), 7.20 (d, J ¼ 3.2 Hz, 2H, flourophenyl H-3, H-5), 7.33
5-(2-Furyl)-1-(4-methanesulfonyl-phenyl)-3-(4-nitrophenyl)-4,5-
dihydro-1H-pyrazole (13h)
(d, J ¼ 3.2 Hz, 2H, methanesulphonylphenyl H-2, H-6), 7.71 (d,
Yield: 62%; grey powder; m.p. 152–154 ꢁC; IR (KBr disk) 2924
1
(C–H aliphatic), 1334, 1137 (SO2); H NMR (DMSO-d6) ꢀ 3.12
J ¼ 9.2 Hz, 2H, methanesulphonylphenyl H-3, H-5), 7.77 (t,
J ¼ 8 Hz, 1H, nitrophenyl H-5), 8.20 (d, J ¼ 8 Hz, 1H, nitrophenyl
H-6), 8.26 (d, J ¼ 6.4 Hz, 1H, nitrophenyl H-4), 8.54 (s, 1H,
nitrophenyl H-2); 13C NMR (DMSO-d6) ꢀ 43.36 (pyrazole C-4),
44.89 (SO2CH3), 63.25 (pyrazole C-5), 113.09, 116.70, 120.78,
123.79, 127.35, 128.99, 129.79, 130.23, 131.52, 133.60, 136.27,
147.26, 148.63, 162.47 (d, J ¼ 247 Hz, C-F); MS (m/z): 439 (M+.,
100%); Anal. Calcd. for C22H18N3O4SF: C, 60.13; H, 4.13; N,
9.56. Found: C, 59.92; H, 3.89; N, 9.66.
(s, 3H, SO2CH3), 3.52 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4),
3.91 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.93 (dd, J ¼ 12.0,
5.6 Hz, 1H, pyrazole H-5), 6.41 (s, 1H, furyl H-5), 6.58 (s, 1H,
furyl H-4), 7.37 (d, J ¼ 8.8 Hz, 2H, methanesulphonylphenyl H-2,
H-6), 7.58 (s, 1H, furyl H-3), 7.75 (d, J ¼ 8.8 Hz, 2H,
methanesulphonylphenyl H-3, H-5), 8.05 (d, J ¼ 8.8 Hz, 2H,
nitrophenyl H-2, H-6), 8.31 (d, J ¼ 8.8 Hz, 2H, nitrophenyl H-3,
H-5); 13C NMR (DMSO-d6) ꢀ 39.72 (pyrazole C-4), 44.88
(SO2CH3), 57.52 (pyrazole C-5), 110.64, 113.14, 120.80, 124.08,
126.55, 128.96, 129.76, 130.35, 131.54, 133.60, 147.40, 148.64,
151.53; MS (m/z): 411 (M+., 73.78%); Anal. Calcd. for
C20H17N3O5S: C, 58.38; H, 4.16; N, 10.21. Found: C, 58.52; H,
4.23; N, 10.37.
5-(4-Dimethylaminophenyl)-1-(4-methanesulfonyl-phenyl)-3-(3-
nitrophenyl)-4,5-dihydro-1H-pyrazole (13l)
Yield: 47%; green powder; m.p. 192–194 ꢁC; IR (KBr disk) 2917
(C–H aliphatic), 1349, 1141 (SO2); 1H NMR (DMSO-d6) ꢀ 2.84
(s, 6H, N(CH3)2), 3.08 (s, 3H, SO2CH3), 3.25 (dd, J ¼ 17.6,
5.6 Hz, 1H, pyrazole H-4), 4.00 (dd, J ¼ 17.6, 12.0 Hz, 1H,
pyrazole H0-4), 5.62 (dd, J ¼ 12.0, 5.6 Hz, 1H, pyrazole H-5),
6.68 (d, J ¼ 8.8 Hz, 2H, dimethylaminophenyl H-3, H-5), 7.10
(d, J ¼ 8.8 Hz, 2H, dimethylaminophenyl H-2, H-6), 7.22
(d, J ¼ 9.2 Hz, 2H, methanesulphonylphenyl H-2, H-6), 7.69 (d,
J ¼ 8.8 Hz, 2H, methanesulphonylphenyl H-3, H-5), 7.77 (t,
J ¼ 8.0 Hz, 1H, nitrophenyl H-5), 8.19 (d, J ¼ 7.6 Hz, 1H,
nitrophenyl H-6), 8.25 (d, J ¼ 6.0 Hz, 1H, nitrophenyl H-4),
8.55 (s, 1H, nitrophenyl H-2); 13C NMR (DMSO-d6) ꢀ 43.61
(pyrazole C-4), 44.92 (SO2CH3), 50.88 (N(CH3)2), 63.57
(pyrazole C-5), 113.09, 113.19, 120.71, 123.55, 126.64, 128.90,
129.02, 129.71, 131.47, 133.93, 147.33, 147.43, 148.61; MS (m/
z): 464 (M+., 36.40%); Anal. Calcd. for C24H24N4O4S: C, 62.05;
H, 5.21; N, 12.06. Found: C, 62.31; H, 5.32; N, 12.17.
1-(4-Methanesulfonyl-phenyl)-3-(3-nitrophenyl)-5-phenyl-4,5-
dihydro-1H-pyrazole (13i)
Yield: 65%; yellow powder; m.p. 194–196 ꢁC; IR (KBr disk) 2922
1
(C–H aliphatic), 1349, 1132 (SO2); H NMR (DMSO-d6) ꢀ 3.09
(s, 3H, SO2CH3), 3.30 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4),
4.08 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.76 (dd, J ¼ 12.0,
5.6 Hz, 1H, pyrazole H-5), 7.20 (d, J ¼ 8.8 Hz, 2H, phenyl H-3, H-
5), 7.25–7.34 (m, 3H, phenyl H-2, H-6, H-4), 7.37 (d, J ¼6.8 Hz,
2H, methanesulphonylphenyl H-2, H-6), 7.70 (d, J ¼ 8.8 Hz, 2H,
methanesulphonylphenyl H-3, H-5), 7.75 (t, J ¼ 7.6 Hz, 1H,
nitrophenyl H-5), 8.21 (d, J ¼ 7.6 Hz, 1H, nitrophenyl H-6),
8.26 (d, J ¼ 6 Hz, 1H, nitrophenyl H-4), 8.55 (s, 1H, nitrophenyl
H-2); 13C NMR (DMSO-d6) ꢀ 43.35 (pyrazole C-4), 44.91
(SO2CH3), 63.93 (pyrazole C-5), 113.08, 120.78, 123.70, 125.51,
128.39, 128.98, 129.60, 129.74, 130.34, 131.51, 133.73, 140.39,
147.26; MS (m/z): 421 (M+., 100%); Anal. Calcd. for
C22H19N3O4S: C, 62.69; H, 4.54; N, 9.97. Found: C, 62.88; H,
4.58; N; 10.04.
1-(4-Methanesulfonylphenyl)-5-(4-methylphenyl)-3-(3-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13m)
Yield: 48%; yellow powder; m.p. 172–174 ꢁC; IR (KBr disk) 2926
1
(C–H aliphatic), 1348, 1137 (SO2); H NMR (DMSO-d6) ꢀ 2.25
(s, 3H, CH3), 3.07 (s, 3H, SO2CH3), 3.25 (dd, J ¼ 17.6, 5.6 Hz,
1H, pyrazole H-4), 4.03 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole
H0-4), 5.68 (dd, J ¼ 12.0, 5.6 Hz, 1H, pyrazole H-5), 7.15 (s,
5-(4-Chlorophenyl)-1-(4-methanesulfonyl-phenyl)-3-(3-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13j)
Yield: 45%; yellow powder; m.p. 222–224 ꢁC; IR (KBr disk) 2922 4H, methylphenyl H-2, H-6, H-3, H-5), 7.22 (d, J ¼ 8.4 Hz,
1
(C–H aliphatic), 1347, 1132 (SO2); H NMR (DMSO-d6) ꢀ 3.09 2H, methanesulphonylphenyl H-2, H-6), 7.68 (d, J ¼ 8.4 Hz, 2H,
(s, 3H, SO2CH3), 3.37 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4), methanesulphonylphenyl H-3, H-5), 7.75 (t, J ¼ 8.0 Hz, 1H,
4.06 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.79 (dd, J ¼ 12.0, nitrophenyl H-5), 8.17 (d, J ¼ 8.0 Hz, 1H, nitrophenyl H-6),
5.6 Hz, 1H, pyrazole H-5), 7.19 (d, J ¼ 8.8 Hz, 2H, chlorophenyl 8.24 (d, J ¼ 8.0 Hz, 1H, nitrophenyl H-4), 8.52 (s, 1H, nitrophenyl
H-2, H-6), 7.32 (d, J ¼ 8.8 Hz, 2H, chlorophenyl H-3, H-5), 7.44 H-2); 13C NMR (DMSO-d6) ꢀ 21.08 (CH3), 43.19 (pyrazole C-4),

DOI: 10.3109/14756366.2016.1158168
1,3,5-Triaryl-4,5-dihydro-1H-pyrazole derivatives
5
44.52 (SO2CH3), 62.96 (pyrazole C-5), 113.04, 120.56, 124.06, Biological evaluation
126.14, 129.04, 130.10, 130.22, 130.92, 132.73, 133.76, 137.59,
COX-1/COX-2 inhibition colorimetric assay
138.62, 147.14, 148.61, 149.11; MS (m/z): 435 (M+., 66.81%);
Anal. Calcd. for C23H21N3O4S: C, 63.43; H, 4.86; N, 9.65. Found: The in vitro inhibition of ovine COX-1/COX-2 was measured
C, 63.3; H, 4.43; N, 9.68.
using an enzyme immunoassay (EIA) kit (Cayman Chemical, Ann
Arbor, MI) according to the manufacturer’s instructions and as
reported before25.
1-(4-Methanesulfonylphenyl)-5-(4-methoxyphenyl)-3-(3-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13n)
In vivo anti-inflammatory activity
Yield: 84%; yellow powder; m.p. 184–186 ꢁC; IR (KBr disk) 2920
1
(C–H aliphatic), 1348, 1136 (SO2); H NMR (DMSO-d6) ꢀ 3.08
Animals
(s, 3H, SO2CH3), 3.28 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4),
3.70 (s, 3H, OCH3), 4.03 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-
4), 5.69 (dd, J ¼ 12.0, 5.6 Hz, 1H, pyrazole H-5), 6.92 (d,
J ¼ 8.8 Hz, 2H, methoxyphenyl H-2, H-6), 7.20 (d, J ¼ 6.8 Hz,
2H, methoxyphenyl H-3, H-5), 7.22 (d, J ¼ 6.0 Hz, 2H, metha-
nesulphonylphenyl H-2, H-6), 7.70 (d, J ¼ 8.8 Hz, 2H, methane-
sulphonylphenyl H-3, H-5), 7.77 (t, J ¼ 8 Hz, 1H, nitrophenyl H-
5), 8.20 (d, J ¼ 8 Hz, 1H, nitrophenyl H-6), 8.27 (d, J ¼ 8 Hz, 1H,
nitrophenyl H-4), 8.54 (s, 1H, nitrophenyl H-2); 13C NMR
Male Wister albino rats with average body weight of 150 g were
used in the experiments. The animals were kept under controlled
environment of humidity 30–60%, 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.
(DMSO-d6)
ꢀ
43.25 (pyrazole C-4), 44.56 (SO2CH3),
Carrageenan induced rat paw edema
55.53(OCH3), 62.73 (pyrazole C-5), 113.08, 115.00, 120.61,
124.06, 127.54, 129.04, 130.21, 130.91, 132.74, 133.53, 133.86,
147.17, 148.66, 149.12, 159.21; MS (m/z): 451 (M+., 100%);
Anal. Calcd. for C23H21N3O5S: C, 61.18; H, 4.69; N, 9.31. Found:
C, 61.44; H, 4.81; N, 9.44.
Rats were divided into 18 groups of five animals each. The first
group was administered vehicle; the second one was admini-
strated celecoxib (50 mg/kg) while the remaining groups were
administrated test compounds (13a–p, 50 mg/kg, and one group
per one compound). Immediately thereafter and under light
anesthesia, the animals received 100 mL of vehicle or carrageenan
(1% in saline) S.C. on the plantar surface of the left hind paw as
reported before26. The development of paw edema was assessed
by measuring paw-volume changes at 1, 3 and 5 h after
carrageenan injection using a pair of dial thickness gauge calipers
accurate to 0.001 cm. The right hind paw served as a reference of
non-inflamed paw for comparison. Results are expressed as paw-
volume change (mL).
5-(2-Chlorophenyl)-1-(4-methanesulfonyl-phenyl)-3-(3-nitrophe-
nyl)-4,5-dihydro-1H-pyrazole (13o)
Yield: 75%; yellow powder; m.p. 198–200 ꢁC; IR (KBr disk) 2926
1
(C–H aliphatic), 1349, 1139 (SO2); H NMR (DMSO-d6) ꢀ 3.10
(s, 3H, SO2CH3), 3.30 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4),
4.17 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.93 (dd, J ¼ 12.0,
5.6 Hz, 1H, pyrazole H-5), 7.01–7.13 (m, 3H, chlorophenyl H-4,
H-5, H-6), 7.37 (d, J ¼6.8 Hz, 2H, methanesulphonylphenyl H-2,
H-6), 7.60 (s, 1H, chlorophenyl H-3), 7.7 (d, J ¼ 8.8 Hz, 2H,
methanesulphonylphenyl H-3, H-5), 7.75 (s, 1H, nitrophenyl H-5),
8.21 (d, J ¼ 7.6 Hz, 1H, nitrophenyl H-4), 8.26 (d, J ¼ 6.8 Hz, 1H,
nitrophenyl H-6), 8.56 (s, 1H, nitrophenyl H-2); 13C NMR
(DMSO-d6) ꢀ 41.94 (pyrazole C-4), 44.89 (SO2CH3), 61.06
(pyrazole C-5), 112.99, 120.82, 123.83, 126.64, 127.90, 129.12,
129.62, 129.77, 130.32, 130.43, 131.55, 131.81, 133.58, 137.11,
147.03, 147.78, 148.62; MS (m/z): 455 (M+., 90.64%); Anal.
Calcd. for C22H18N3O4SCl: C, 57.96; H, 3.98; N, 9.22. Found: C,
57.7; H, 3.80; N, 9.17.
Additionally, the ED50 values for the most potent derivatives
(13d, 13f, 13k and 13o) were calculated using three different
doses and paw thickness of each rat was measured after 3 h of
carrageenan injection according to the reported procedure26.
Ulcerogenic liability study
Ulcerogenic liability for the most biologically active synthesized
compounds (13d, 13f, 13k and 13o), celecoxib and aspirin was
evaluated using the previously reported procedures27. Adult male
albino rats weighing between 120 and 150 g were used in this
study and divided into seven groups each of five animals. The
animals were fasted for 20 h before drug administration. The first
group was given 1% aqueous solution of tween 80 and was used as
the control group. The second and third groups received celecoxib
and aspirin, respectively, were used as reference drugs in a dose
5-(2-Furyl)-1-(4-methanesulfonylphenyl)-3-(3-nitrophenyl)-4,5-
dihydro-1H-pyrazole (13p)
Yield: 73%; green powder; m.p. 186–188 ꢁC; IR (KBr disk) 2923 100 mg/kg suspended in 1% tween. The remaining groups
1
(C–H aliphatic), 1348, 1131 (SO2); H NMR (DMSO-d6) ꢀ 3.11 received the tested compounds (13d, 13f, 13k and 13o) in a
(s, 3H, SO2CH3), 3.56 (dd, J ¼ 17.6, 5.6 Hz, 1H, pyrazole H-4), dose 50 mg/kg suspended in 1% tween. Treatment was continued
3.93 (dd, J ¼ 17.6, 12.0 Hz, 1H, pyrazole H0-4), 5.91 (dd, J ¼ 12.0, once daily for three successive days in all groups. Two hours after
5.6 Hz, 1H, pyrazole H-5), 6.41 (s, 1H, furfural H-5), 6.57 (s, 1H, the last dose, rats were sacrificed under general anesthesia and the
furfural H-4), 7.37 (d, J ¼ 8.8 Hz, 2H, methanesulphonylphenyl stomach was removed, opened along the greater curvature and
H-2, H-6), 7.58 (s, 1H, furfural H-3), 7.74 (d, J ¼ 8.8 Hz, 2H, rinsed with saline. The gastric mucosa was examined with a
methanesulphonylphenyl H-3, H-5), 7.79 (d, J ¼ 8 Hz, 1H, magnifying lens (10ꢂ) for the presence of lesions in the form of
nitrophenyl H-5), 8.24 (d, J ¼ 8 Hz, 1H, nitrophenyl H-6), 8.28 hemorrhages or linear breaks and erosions. The expression of the
(d, J ¼ 8 Hz, 1H, nitrophenyl H-4), 8.56 (s, 1H, nitrophenyl H-2); degree of ulcerogenic effect was in terms of dividing the
13C NMR (DMSO-d6) ꢀ 39.92 (pyrazole C-4), 44.92 (SO2CH3), percentage incidence of ulcers in each group of animal by 10,
57.36 (pyrazole C-5), 107.90, 110.64, 113.14, 120.80, 123.79, the average number of ulcers per stomach and the visual
128.96, 129.76, 130.35, 131.54, 133.60, 142.96, 147.40, 148.64, observation of the ulcer score (average severity of ulcer). The
151.53; MS (m/z): 411 (M+., 79.48%); Anal. Calcd. for ulcer scores are divided into 0 ulcer score which indicates no
C20H17N3O5S: C, 58.38; H, 4.16; N, 10.21. Found: C, 58.49; H, ulcer, 1 ulcer score which indicates only mucosal erythema, 2
4.21; N, 10.42.
ulcer score which indicates mild mucosal edema, slight bleeding

6
K. R. A. Abdellatif et al
J Enzyme Inhib Med Chem, Early Online: 1–11
or slight erosions, 3 ulcer score which indicates moderate edema, Results and discussion
bleeding ulcers or erosions and 4 ulcer index which indicates
Chemistry
severe ulceration, erosions, edema and tissue necrosis. The sum
of all above values indicates the ulcer index.
A group of 3-(3/4-nitrophenyl)-5-(substituted-aryl)-1-(4-methane-
sulphonylphenyl)-4,5-dihydro-1H-pyrazoles (13a–p) were synthe-
sized using the reaction sequence illustrated in Scheme 1.
Accordingly, the reaction of 3-nitro and 4-nitroacetophenone
(9a, b) with different aldehydes 10a–h provided the correspond-
ing chalcones 11a–p which upon cyclization with 4-methanesul-
fonylphenylhydrazine hydrochloride (12) in ethanol under reflux
conditions gave the target triarylpyrazole derivatives 13a–p in
good yields (45–84%). All the newly synthesized compounds have
Statistical analysis
Significant difference among groups was assessed using two way
ANOVA followed by post hoc Tukey test. The results were
expressed as mean standard error (SE). Differences were
considered significant at *p50.01.
Molecular modeling
1
been characterized by IR, H NMR, 13C NMR, mass spectra and
The crystal structures of celecoxib bound at the COX-2 (PDB elemental analyses.
ID: 2AW1) active sites28 (obtained from protein data bank at
The IR spectra of dihydropyrazole compounds 13a–p showed
Research Collaboration for Structural Bioinformatics (RSCB) two sharp peaks at 1141–1131 cmꢀ1 and 1349–1322 cmꢀ1
1
protein database [PDB]). Docking of the co-crystallized ligand corresponding to SO2. The H NMR spectra of dihydropyrazole
should be carried out to study the scoring energy (s), root mean compounds 13a–p showed three signals as doublet of doublet
standard deviation (rmsd) and amino acid interactions. Root (dd), each of one proton intensity, one at ꢀ 3.23–3.56, second at ꢀ
mean square deviation (rmsd) which is the measure of super- 3.91–4.17, and the third at ꢀ 5.46–5.94 with three different J
˚
posing was 0.50 A for the lead compounds. Docking was values (17.6, 12.0, 5.6 Hz) corresponding to three protons of the
performed using London dG force and refinement of the results dihydropyrazole ring. The highest J value was due to geminal
was achieved using force field energy. Preparation of the s coupling of two protons at position 4 while the other two J values
compounds for docking was achieved via their 3D structure built due to coupling of two geminal protons with proton at position 5.
by Molecular Operating Environment (MOE, Version 2005.06, Additionally, 13C NMR spectra of 13a–p confirmed the presence
Chemical Computing Group Inc., Montreal, Quebec, Canada). of dihydropyrazole ring through presence of three peaks at ꢀ
Certain procedures were taken before docking which include: 3D 39.72–43.61, 61.06–64.12 and 147.26–149.04 corresponding to
protonation of the structures, running conformational analysis dihydropyrazole C-4, C-5 and C-3, respectively.
using systemic search, selecting the least energetic conformer
and applying the same docking protocol used with ligands. Biological evaluation
Docking for the most active biologically compounds (13d, 13f,
In vitro COX inhibition assay
13k and 13o) was applied. Binding interactions between the
amino acid residues and functional groups of the compounds are In vitro structure–activity relationships acquired for this group of
summarized in Table 5.
triarylpyrazole derivatives (13a–p) showed that they exhibit a
COCH3
R
Scheme 1. Reagents and conditions: (a)
MeOH, NaOH, RT, 12 h; (b) EtOH, reflux,
12–18 h.
Ar
a
+
Ar CHO
O
10a-h
R
9a-b
11a-p
Ar
a; R = 4-NO2
b; R = 3-NO2
a; C6H5
b; 4-ClC6H4
c; 4-FC6H4
d; 4-N(CH3)2-C6H4
e; 4-CH3C6H4
f; 4-OCH3C6H4
g; 2-ClC6H4
h; 2-furyl
12, b
Ar
SO2CH3
N
R
N
SO2CH3
13a-p
NHNH2 .HCl
12
R
Ar
R
Ar
C6H5
4-ClC6H4
4-FC6H4
4-N(CH3)2C6H4
4-CH3C6H4
4-OCH3C6H4
2-ClC6H4
C6H5
4-ClC6H4
4-FC6H4
4-N(CH3)2C6H4
4-CH3C6H4
4-OCH3C6H4
2-ClC6H4
2-furyl
a; 4-NO2
b; 4-NO2
c; 4-NO2
d; 4-NO2
e; 4-NO2
f; 4-NO2
g; 4-NO2
h; 4-NO2
i; 3-NO2
j; 3-NO2
k; 3-NO2
l; 3-NO2
m; 3-NO2
n; 3-NO2
o; 3-NO2
p; 3-NO2
2-furyl

DOI: 10.3109/14756366.2016.1158168
1,3,5-Triaryl-4,5-dihydro-1H-pyrazole derivatives
7
Table 1. In vitro COX-1 and COX-2 inhibition of triarylpyrazoles 13a–p Table 2. Anti-inflammatory activities for triarylpyrazoles 13a–p and
and celecoxib.
celecoxib.
IC50 (mM)a
Mean change in edema thickness (% inhibition)
Compound no.
COX-1
COX-2
COX-2 S.I.b Compound no.
1 h
3 h
5 h
13a
13b
13c
13d
13e
10.4
13.4
9.6
8.7
7.6
3.4
5.9
8.3
4.9
11.3
6.5
12.8
6.8
6.5
11.6
3.4
3.4
4.6
3.4
2.9
1.8
0.74
1.5
1.8
1.6
5.4
2.1
4.5
1.3
1.8
4.1
0.87
1.3
3.06
2.91
2.82
3
Celecoxib
13a
13b
13c
13d
13e
92.77*
78.05*
40.87*
40.08*
93.43*
51.51*
66.1*
97.77*
86.71*
70.42*
82.73*
97.18*
83.32*
95.92*
88.46*
85.16*
93.21*
92.14*
91.37*
80.11*
74.20*
86.52*
97.18*
86.61*
99.51*
91.75*
91.09*
97.47*
99.34*
95.67*
98.61*
97.06*
97.87*
98.53*
98.20*
99.10*
96.00*
91.34*
97.87*
99.10*
98.45*
4.22
4.59
3.93
4.61
3.06
2.09
3.09
2.84
5.23
3.61
2.83
3.91
6.07
13f
13g
13h
13i
13j
13k
13l
13m
13n
13o
13p
Celecoxib
13f
13g
13h
13i
13j
13k
13l
13m
13n
13o
13p
60.58*
47.83*
76.35*
37.58*
69.14*
40.73*
53.74*
41.26*
74.24*
46.91*
7.9
aIC50 value represents the compound concentration that is required to *p50.01 significantly different from control at p50.01.
produce 50% inhibition of COX-1 or COX-2 which is the mean value of
two determinations where the deviation from the mean is 510% of the
mean value.
Table 3. The anti-inflammatory activity (ED50, mmol/kg)
of most potent triarylpyrazoles 13d, 13f, 13k, 13o and
celecoxib.
bSelectivity index (COX-1 IC50/COX-2 IC50).
broad range (moderately potent to weekly potent) of COX-1
(IC50 ¼ 3.4–13.4 mM), and COX-2 (IC50 ¼ 0.74–5.4 mM range, see
data in Table 1), inhibitory activities. All compounds were more
potent inhibitors for COX-2 isozyme than COX-1 isozyme.
Compounds having 4-CH3C6H4 (13e, 13m), 4-OCH3C6H4 (13f,
13n) and 2-furyl (13h, 13p) moieties were generally more potent
inhibitors of COX-2 and in turn more COX-2 selective (COX-
2 S.I.¼3.61–5.23) than compounds having the other moieties. The
4-methoxy derivative (13f) was the most potent COX-2 inhibitor
(IC50 ¼ 0.74 mM) while the 4-tolyl derivative (13m) was the most
COX-2 selective (S.I.¼5.23) in comparison with the reference
drug celecoxib (COX-2 IC50 ¼ 1.3 mM, S.I.¼6.07).
Compound no.
ED50 (mmol/kg)a
13d
13f
13k
13o
66.5
73.4
79.8
70.5
68.1
Celecoxib
aInhibitory 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 at the specified dose (mmol/kg).
respectively) comparable to that of celecoxib (92.77–99.51%)
and were the most potent derivatives among the 16 triarylpyrazole
compounds (13a–p).
In vivo anti-inflammatory activity
The anti-inflammatory activity of the all prepared triarylpyrazole
derivatives (13a–p) were evaluated using carrageenan-induced rat
paw edema assay. Each compound was administered orally
(100 mg/kg) immediately prior to induction of inflammation by
carrageenan subcutaneous injection. The anti-inflammatory activ-
ity was then calculated based on paw-volume changes at 1, 3 and
5 h after carrageenan injection as presented in Table 2.
A comparable study of the anti-inflammatory activity of the
test compounds relative to celecoxib as a reference drug at
different time intervals indicated that after 1 h, the triarylpyrazole
derivatives (13a–p) showed edema inhibition percentage activ-
ities 37.58–93.43% and the 4-dimethylamino derivative (13d) was
Moreover, the ED50 values for the most potent derivatives
(13d, 13f, 13k, 13o) were calculated in comparison with celecoxib
(Figures 3–6). The four derivatives showed good anti-inflamma-
tory activities (ED50 ¼ 66.5–79.8 mmol/kg), while 4-dimethyla-
mino derivative 13d (ED50 ¼ 66.5 mmol/kg) was more potent than
celecoxib (ED50 ¼ 68.1 mmol/kg), 4-methoxy derivative 13f,
4-fluoro derivative 13k and 2-chloro derivative 13o were less
potent but with acceptable ED50 values (ED50 ¼ 73.4, 79.8 and
70.5 mmol/kg, respectively).
Ulcerogenic liability
the most potent one (93.43% edema inhibition) while after 3 h, The most potent anti-inflammatory compounds (13d, 13f, 13k
13a–p showed higher edema inhibition percentage activities and 13o), low ulcerogenic reference drug (celecoxib) and high
70.42–97.18% and both 4-dimethylamino derivative 13d and 2- ulcerogenic reference drug (aspirin) were subjected to ulcerogenic
chloro derivative 13o were the most potent derivatives (97.18% liability at 100 mg/kg dose and the results are recorded in Table 4.
edema inhibition for both) (Table 3). After 5 h, all compounds It was clear that the tested compounds caused ulceration effect
showed higher edema inhibition percentage activities of 91.09– comparable to that of celecoxib (the relative ulcerogenicity of
99.10 and the 4-dimethylamino derivative (13d) was still the the tested compounds to celecoxib ¼ 1.16–1.48). While the 4-
highest potent derivative (99.10% edema inhibition). At all time dimethylamino derivative 13d (ulcer index ¼ 3.89) was the least
intervals (1, 3 and 5 h), 4-dimethylamino derivative 13d, 4- ulcerogenic derivative in comparison with celecoxib (ulcer
methoxy derivative 13f, 4-fluoro derivative 13k and 2-chloro index ¼ 3.35), the other three derivatives (13f, 13k, 13o)
derivative 13o displayed good anti-inflammatory activities showed ulcerogenic potential (ulcer index ¼ 4.86, 4.96 and 3.92,
(93.43–99.34, 66.1–98.61, 69.14–99.10 and 74.24–99.10%, respectively) slightly higher than celecoxib (ulcer index ¼ 3.35).

8
K. R. A. Abdellatif et al
J Enzyme Inhib Med Chem, Early Online: 1–11
Figure 3. 2D binding interaction of 13d
inside COX-2 active site.
Figure 4. 2D binding interaction of 13f inside
COX-2 active site.
In comparison with the traditional NSAID aspirin (ulcer index interactions between the amino acid residues and functional
¼ 22.75), all the tested compounds were about 4–6 folds less groups of the compounds are summarized in Table 5.
ulcerogenic with relative ulcerogenicity range of 0.17–0.22.
While compounds 13d and 13f showed appreciable binding
interactions (affinity in kcal/mol ꢀ6.9498 and ꢀ6.7965, respect-
ively), compounds 13k and 13o showed binding interactions
(affinity in kcal/mol ꢀ2.5760 and ꢀ2.1774, respectively) in
comparison with celecoxib (affinity in kcal/mol ꢀ6.5330).
Molecular modeling
To know the plausible mode of interactions of the most potent
anti-inflammatory compounds (13d, 13f, 13k and 13o), molecular
docking experiments were performed using X-ray crystal structure
data for COX-2 obtained from the protein data bank using
Conclusion
the COX-2 selective reference drug (celecoxib, 1) as a ligand A new series of 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives
(Figure 7). The docking results including the energy associated 13a–p were synthesized for evaluation as COX inhibitors, anti-
with intermolecular interactions (affinity in kcal/mol) obtained inflammatory agents and ulcerogenic liability. Structure–activity
upon computational docking for all compounds (13d, 13f, 13k, data acquired and biological studies showed that (i) all com-
13o and celecoxib) within COX-2 active sites and the binding pounds were more potent COX-2 inhibitors than COX-1, (ii) most

DOI: 10.3109/14756366.2016.1158168
1,3,5-Triaryl-4,5-dihydro-1H-pyrazole derivatives
9
Figure 5. 2D binding interaction of 13k
inside COX-2 active site.
Figure 6. 2D binding interaction of 13o inside
COX-2 active site.
Table 4. Ulcerogenic effect of triarylopyrazoles 13d, 13f, 13k, 13o, aspirin and celecoxib.
Compound
Average severity
Average no of ulcers
% incidence/10
Ulcer index
Relative ulcerogenicity to celecoxib aspirin
13d
13f
13k
13o
Aspirin
Celecoxib
0.63 0.005
0.5 0.025
0.61 0.013
0.65 0.004
3.75
0.26 0.003
0.36 0.004
0.35 0.006
0.27 0.014
9
3
4
4
3
10
2
3.89
4.86
4.96
3.92
22.75
3.35
1.16
1.45
1.48
1.17
6.79
1
0.17
0.21
0.22
0.17
1
0.6 0.021
0.75 0.022
0.15
Values represent means SEM of five animals for each group. Statistical analysis using one-way ANOVA.

10 K. R. A. Abdellatif et al
J Enzyme Inhib Med Chem, Early Online: 1–11
Figure 7. 2D binding interaction of celecoxib
inside COX-2 active site.
Table 5. Molecular modeling data for compounds 13d, 13f, 13k, 13o and celecoxib during docking in COX-2 (PDB ID:
1CX2) active site.
˚
Distance (in A) from main residue
Compound
Affinity (kcal/mol)
Functional group
Interaction
13d
13f
ꢀ6.9498
ꢀ6.7965
4.37
ꢀ2.5760
ꢀ2.1774
2.72
4.27
4.02
Arg120
3.26
2.75
Tyr385
Arg120
2.91
Arg120
Lys83
–Ph-ring
Ile517
Arg513
–NO2
–Ph-ring
Arg513
–SO2
–Ph-ring
–Ph-ring
pi-cation
–SO2
pi-cation
pi-cation
13k
13o
H-acceptor
H-acceptor
–SO2
H-acceptor
pi-cation
–SO2
4.28
ꢀ6.5330
Celecoxib
H-acceptor
2.51
Arg120
H-acceptor
4. Rathish IG, Javed K, Ahmad S, et al. Synthesis and antiinflamma-
tory activity of some new 1,3,5-trisubstituted pyrazolines bearing
benzene sulfonamide. Bioorg Med Chem Lett 2009;19:255–8.
of the evaluated compounds showed good anti-inflammatory
activity at different time intervals especially compounds 13d, 13f,
13k and 13o, (iii) while compound 13d was more potent than
celecoxib compounds, 13f, 13k and 13o were less potent but with
acceptable ED50 values and (iv) the four compounds (13d, 13f,
13k and 13o) were 4–6 folds less ulcerogenic than aspirin and
showed ulceration effect comparable to that of celecoxib.
´
5. Dogne JM, Supuran CT, Pratico D. Adverse cardiovascular effects of
the coxibs. J Med Chem 2005;48:2251–7.
6. Abdellatif KRA, Chowdhury MA, Knaus EE. Synthesis of new
1-[4-methane (amino) sulfonylphenyl)]-5-[4-(aminophenyl)]-3-tri-
fluoromethyl-1H-pyrazoles. J Het Chem 2008;45:1707–10.
7. Abdellatif KRA, Chowdhury MA, Dong Y, Knaus EE. Diazen-1-
ium-1,2-diolated nitric oxide donor ester prodrugs of 1-(4-metha-
nesulfonylphenyl)-5-aryl-1H-pyrazol-3-carboxylic acids: synthesis,
nitric oxide release studies and anti-inflammatory activities. Bioorg
Med Chem 2008;16:6528–34.
Declaration of interest
The authors have declared no conflict of interest.
8. Abdellatif KRA, Chowdhury MA, Dong Y, et al. Diazen-1-ium-1,2-
diolated nitric oxide donor ester prodrugs of 5-(4-hydroxymethyl-
phenyl)-1-(4-aminosulfonylphenyl)-3-trifluoromethyl-1H-pyrazole
and its methanesulfonyl analog: synthesis, biological evaluation and
nitric oxide release studies. Bioorg Med Chem 2008;16:9694–8.
9. Chowdhury MA, Abdellatif KRA, Dong Y, Knaus EE. Synthesis of
new 4-[2-(4-methyl(amino)sulfonylphenyl)-5-trifluoromethyl-2H-
pyrazol-3-yl]-1,2,3,6-tetrahydropyridines: a search for novel nitric
oxide donor anti-inflammatory agents. Bioorg Med Chem 2008;16:
8882–8.
References
1. Nonato FR, Nogueira TMO, Barros TAA, et al. Antinociceptive and
anti-inflammatory activities of Adiantum latifolium lam.: evidence
for a role of IL-1b inhibition. J Ethnopharm 2011;136:518–24.
2. Al-Hourani BJ, Sharma SK, Mane JY, et al. Synthesis and evaluation
of 1,5-diaryl-substituted tetrazoles as novel selective cyclooxygen-
ase-2 (COX-2) inhibitors. Bioorg Med Chem Lett 2011;21:1823–6.
3. Ghodsi R, Zarghi A, Daraei B, Hedayati M. Design, synthesis and
biological evaluation of new 2,3-diarylquinoline derivatives as
selective cyclooxygenase-2 inhibitors. Bioorg Med Chem Lett 2010;
18:1029–33.
10. Abdellatif KRA, Elshemy HAH, Salama. SA, Omar HA.
Synthesis, characterization and biological evaluation of novel

DOI: 10.3109/14756366.2016.1158168
1,3,5-Triaryl-4,5-dihydro-1H-pyrazole derivatives 11
40-fluoro-20-hydroxy-chalcones derivatives as antioxidant, anti- 19. Qiu X, Li S, Shi A. Synthesis and biological activities of chalcones
inflammatory and analgesic agents. J Enz Inhib Med Chem
2015;30:484–91.
11. Abdellatif KRA, Abdelwahab MA, Labib M, Zidan TH. Synthesis,
cyclooxygenase inhibition, anti-inflammatory evaluation and ulcero-
derived from nitroacetophenone. Adv Mater Res 2012;518:255–60.
20. Mageed IY, Jassim WK, Ahmed A, Jaasim IK. Synthesis and
characterization of some new compounds including heterocyclic
units. Aust J Basic Appl Sci 2014;8:404–11.
genic liability of novel triarylpyrazoline derivatives as selective 21. Balaji PN, Sai Sreevani M, Harini P, et al. Antimicrobial activity of
COX-2 inhibitors. Bioorg Med Chem Lett 2015;25:5787–91.
some novel synthesized heterocyclic compounds from substituted
chalcones. J Chem Pharm Res 2010;2:754–8.
CYP2C9 structure – metabolism relationships: optimizing the 22. Azam MA, Suresh B. Synthesis and biological evaluation of some
¨
¨
12. Ahlstrom MM, Redderstrom M, Zamora I, Luthman K.
metabolic stability of COX-2 inhibitors. J Med Chem 2007;50: novel 2-mercaptobenzothiazoles carrying 2-pyrazoline. J Sci Ind Res
4444–52. 2012;71:113–19.
13. Romagnoli R, Baraldi PG, Carrion MD, et al. Hybrid alpha- 23. Mamaghani M, Mahmoodi NO, Moghisseh AA, Pourmohamad L.
bromoacryloylamido chalcones. Design, synthesis and biological
evaluation. Bioorg Med Chem Lett 2009;19:2022–8.
14. Gupta RA, Kaskhedikar SG. Synthesis, antitubercular activity, and
Synthesis and kinetic resolution of furyl substituted secondary
carbinols by porcine pancreatic lipase under solvent free conditions.
J Iran Chem Soc 2008;5:238–43.
´
QSAR analysis of substituted nitroaryl analogs: chalcone, pyrazole, 24. Abdellatif KRA, Chowdhury MA, Velazquez C, et al. Celecoxib
isoxazole, and pyrimidines. Med Chem Res 2013;22:3863–80.
15. Fun HK, Chantrapromma S, Patil PS, et al. (E)-3-(4-methyl-phen-
yl)-1-(4-nitro-phenyl)prop-2-en-1-one. Acta Crystallograph E Struct
Reprts Online 2008;64:o954–5.
16. Indorkar D, Chourasia OP, Limaye SN. Synthesis and characteriza-
tion of some new synthesis of 1-acetyl-3-(4-nitrophenyl)-5-(sub-
prodrugs possessing a diazen-1-ium-1,2-diolate nitric oxide donor
moiety: synthesis, biological evaluation and nitric oxide release
studies. Bioorg Med Chem Lett 2010;20:4544–9.
25. Roschek BJ, Fink RC, Li D, et al. Pro-inflammatory enzymes,
cyclooxygenase 1, cyclooxygenase 2, and 5-lipooxygenase, inhibited
by stabilized rice bran extracts. J Med Food 2009;12:615–23.
stituted phenyl) pyrazoline derivative and antimicrobial activity. Int 26. Winter CA, Risley EA, Nuss GW. Carrageenin-induced edema in
J Curr Microbial APP Sci 2015;4:670–8.
hind paw of the rat as an assay for antiiflammatory drugs. Proc Soc
Exp Biol 1962;111:544.
bacterial activity of some heterocyclic chalcone derivatives bearing 27. Hassan GS, Abou-Seri SM, Kamel G, Ali MM. Celecoxib analogs
17. Zheng CJ, Jiang SM, Chen ZH, et al. Synthesis and anti-
thiofuran, furan, and quinoline moieties. Archiv Pharm 2011;344:
689–95.
18. Mishra SK, Sahoo SP, Panda K, et al. Synthesis and antimicrobial
bearing benzofuran moiety as cyclooxygenase-2 inhibitors: design,
synthesis and evaluation as potential anti-inflammatory agents. Eur J
Med Chem 2014;76:482–93.
activity of some 1-(2,4-dinitro-phenyl)-3-(3-nitrophenyl)-5-(4-sub- 28. Wang JL, Limburg D, Graneto MJ, et al. The novel benzopyran class
stituted phenyl)-4-bromo-2-pyrazolines and 1-(2,4-dinitrophenyl)-3-
(3-nitrophenyl)-5-(4-substituted phenyl)-2-pyrazoline-4-ones. Acta
Pol Pharmaceut Drug Res 2007;64:359–64.
of selective cyclooxygenase-2 inhibitors. Part 2: The second clinical
candidate having a shorter and favorable human half-life. Bioorg
Med Chem Lett 2010;20:7159–63.
Supplementary material available online