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

Article abstract of DOI:10.1007/s12272-015-0606-7

A novel series of 2-pyrazoline derivatives 13a-l was synthesized via aldol condensation of 4-substituted acetophenones with appropriately substituted aldehydes followed by cyclization of the formed chalcones with 4-hydrazinobenzenesulfonamide hydrochlorid

Full text of DOI:10.1007/s12272-015-0606-7

Arch. Pharm. Res.
DOI 10.1007/s12272-015-0606-7
RESEARCH ARTICLE
Synthesis and anti-inflammatory evaluation of new
1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives possessing
an aminosulphonyl pharmacophore
Khaled R. A. Abdellatif1 Mohamed A. Abdelgawad1 Heba A. H. Elshemy1
•
•
•
Shahinda S. R. Alsayed1 Gehan Kamel2
•
Received: 22 January 2015 / Accepted: 18 April 2015
Ó The Pharmaceutical Society of Korea 2015
Abstract A novel series of 2-pyrazoline derivatives 13a–l was
synthesized via aldol condensation of 4-substituted acetophe-
nones with appropriately substituted aldehydes followed by cy-
clization of the formed chalcones with 4-hydrazinobenzene-
sulfonamide hydrochloride. The chemical structures of the target
pyrazoline derivatives were proved by means of IR, 1HNMR,13C
NMR, mass spectroscopy and elemental analyses data. All the
synthesized compounds were evaluated for their cyclooxygenase
selectivity, anti-inflammatory and ulcerogenic liability. While
compounds 13e, 13h and 13i showed moderate COX-2 selec-
tivity in vitro and good anti-inflammatory activity in vivo, com-
pound 13i showed the highest anti-inflammatory activity that is
very close in potency to the reference drug (celecoxib) with better
gastric profile than celecoxib.
isoforms, a constitutive form (COX-1) and an inducible form
(COX-2). The constitutive COX-1 plays a critical role as a
housekeeping enzyme which is responsible for the mainte-
nance of physiological functions such as protection of gastric
mucosa, vascular homeostasis and platelet aggregation. The
inducible COX-2 is significantly upregulated during acute
and chronic inflammation, pain and oncogenesis (Rathish
et al. 2009; Al-Hourani et al. 2011). Traditional NSAIDs
such as aspirin, ibuprofen and indomethacin interact with
both forms (COX-1 and COX-2) leading to the inhibition of
gastro protective PGs synthesized through COX-1 pathway
and therefore their long term administration even at low
prophylactic doses resulting in gastrointestinal side effects
ranging from ulcers to perforation and bleeding (Zarghi et al.
2009). For this reason, the synthesis of selective COX-2 in-
hibitor drugs (coxibs) takes much consideration in recent
years that achieve the same anti-inflammatory efficacy as
traditional NSAIDs, but with minimal risk of unwanted
gastrointestinal side effects mediated through the inhibition
of COX-1 enzyme (Rathish et al. 2009). Celecoxib (1), ro-
fecoxib (2) and valdecoxib (3) are the most common coxibs
approved for marketing (Fig. 1). However, adverse bio-
chemical changes in the COX pathway caused by highly
selective COX-2 inhibitors are believed to be responsible for
the increased incidences of high blood pressure and my-
ocardial infarction that led to the withdrawal of rofecoxib
Keywords Dihydropyrazole Á Cyclooxygenase
inhibition Á Anti-inflammatory
Introduction
The anti-inflammatory activity of non-steroidal anti-in-
flammatory drugs (NSAIDs) results from the inhibition of
cyclooxygenase enzyme which catalyze the production of
pro-inflammatory prostaglandins (PGs) and thromboxanes
(TXs) (Zarghi et al. 2007; Zebardast et al. 2009). It is well
known that cyclooxygenase enzyme exists in two distinct
´
and valdecoxib from market (Scheen 2004; Dogne et al.
2005). In this context, celecoxib is one of the most important
highly marketed COX-2 selective drugs till now (Ovais et al.
2012). In earlier studies, we reported some derivatives of
celecoxib (4–8) (Abdellatif et al. 2008a, b, c; Chowdhury
et al. 2008a, b; Abdellatif et al. 2009) (Fig. 1) having com-
parable activities with celecoxib as COX-2 selective com-
pounds with maintaining the pyrazole nucleus of celecoxib.
But due to serious side effects such as water and salt
& Khaled R. A. Abdellatif
khaled.ahmed@pharm.bsu.edu.eg
1
Department of Pharmaceutical Organic Chemistry, Faculty of
Pharmacy, Beni-Suef University, Beni Suef 62514, Egypt
2
Department of Pharmacology, Faculty of Veterinary, Cairo
University, Cairo, Egypt
123

K. R. A. Abdellatif et al.
Fig. 1 Chemical structures of some selective cyclooxygenase-2 (COX-2) inhibitors (1–8)
retention, bone marrow depression and carcinogenesis, the
use of pyrazole derivatives has been limited (Fioravanti et al.
2010). This limitation has led to the investigation of novel
pyrazole derivatives with more potent anti-inflammatory
activity and less gastrointestinal toxicity. Many selective
COX-2 inhibitors belong to a group of compounds having a
central tri-substituted planar ring, five-membered hetero-
cyclic ring, attached to pendent benzene rings and a lipo-
philic group. One of the phenyl rings is bearing SO2NH2
moiety which is believed to induce COX-2 selectivity
(Habeeb et al. 2001). 2-Pyrazoline ring system is an impor-
tant nitrogenous five-membered heterocyclic component of
the drugs and has attracted significant interest in medicinal
chemistry over the past few decades. Literature survey de-
clared that many pyrazoline derivatives have found their
clinical application as NSAIDs. For example, Antipyrine,
2,3-dimethyl-1-phenyl-3-pyrazolin-5-one, was found to be
the first pyrazoline derivative used in the management of
pain and inflammation. In addition, several related analogues
of pyrazolidin-3,5-diones, pyrazolin-3-ones and pyrazolin-
5-ones are also available as NSAIDs; examples are fel-
cobuzone, mefobutazone, morazone, famprofazone, and
ramifenazone (Khode et al. 2009). Besides these, many
scaffolds containing the 2-pyrazoline,4,5-dihydropyrazole,
heterocyclic are also reported in literature as having potent
anti-inflammatory (Rathish et al. 2009; Bano et al. 2011;
Bashir et al. 2011; Ovais et al. 2012, 2013; Khode et al.
2009), antidepressant, anti-bacterial (Johnson et al. 2007),
anticancer (Rostom 2006; Johnson et al. 2007), anti-tuber-
cular, analgesic (Sahu et al. 2008; Chandra et al. 2010), anti-
diabetic (Ahn et al. 2004) and CB1 receptor antagonism for
obesity (Lange et al. 2005). So, pyrazolines are considered
123

Synthesis and anti-inflammatory evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole…
useful lead molecules as they show significant pharmaco-
logical properties and clinical applications. Due to the great
potential of both moieties, benzenesulfonamide and pyra-
zoline, the synthesis of pyrazolines bearing benzenesulfon-
amide was carried out to evaluate their anti-inflammatory
activities.
slowly and the reaction mixture was stirred at room tem-
perature for 12 h. The obtained solid was filtered, washed
with water (5 mL) and crystallized from methanol to yield
analytically pure compounds 11k and 11l for which phy-
sical and spectral data are listed below.
Motivated by aforesaid findings and as a part of our
ongoing research, we now describe the synthesis and anti-
inflammatory (AI) activity for a new group of 1,3,5-triaryl-
4,5-dihydro-1H-pyrazoles 13a–l as celecoxib derivatives in
which; (i) pyrazole ring of celecoxib was replaced with
dihydropyrazole nucleus, (ii) trifluoromethyl moiety was
replaced with 4-substituted aryl moiety since it was re-
ported that the substituent at pyrazole C-3 has very few
steric restrictions with respect to COX-2 suggesting that
3-(Fur-2-yl)-1-(4-isobutylphenyl)prop-2-en-1-one (11k) Yield:
75 %; mp 54–56 °C; IR (KBr): 3037 (CH aromatic), 2923
(CH aliphatic), 1656 (C=O) cm-1; 1H NMR (DMSO-d6) d
0.82 (d, J = 6.4 Hz, 6H, CH2CH(CH3)2), 1.83 (m, 1H,
CH2CH(CH3)2), 2.47 (d, J = 7.2 Hz, 2H, CH2CH(CH3)2),
6.66 (dd, J = 3.4, 1.8 Hz, 1H, furyl H-4), 7.08 (d,
J = 3.4 Hz, 1H, furyl H-5), 7.28 (d, J = 7.6 Hz, 2H, iso-
butylphenyl H-3, H-5), 7.55 (d, J = 15.2 Hz, 1H,
COCH = CH), 7.85 (d, J = 15.2 Hz, 1H, COCH = CH),
7.89 (d, J = 1.8 Hz, 1H, furyl H-3), 7.97 (d, J = 7.6 Hz, 2H,
isobutylphenyl H-2, H-6); 13C NMR (DMSO-d6) d 22.5,
29.8, 44.8, 113.5, 117.2, 119.1, 128.6, 129.6, 130.4, 135.4,
146.4, 147.3, 151.6, 188.4; MS (m/z): 254 (M?., 75 %), 211
(100 %); Anal. Calcd for C17H18O2: C, 80.28; H, 7.13.
Found: C, 80.45; H, 6.87.
¨
COX-2 inhibition should be retained (Ahlstrom et al.
2007), (iii) tolyl group was maintained or replaced with
different aryl or heteroaryl moieties and (iv) aminosulfonyl
group on the N1-phenyl ring was maintained because
aminosulfonyl or methylsulfonyl group is essential for
potent and selective COX-2 inhibitory activity.
1-(4-Isobutylphenyl)-3-(thien-2-yl)-prop-2-en-1-one (11l)
Yield: 70 %; mp 60–62 °C; IR (KBr): 3072 (CH aromatic),
2920 (CH aliphatic), 1648 (C=O) cm-1; 1H NMR (DMSO-
d6) d 0.85 (d, J = 6.4 Hz, 6H, CH2CH(CH3)2), 1.86 (m, 1H,
CH2CH(CH3)2), 2.52 (d, J = 7.2 Hz, 2H, CH2CH(CH3)2),
7.19 (dd, J = 4.8, 3.2 Hz, 1H, thienyl H-4), 7.32 (d,
J = 7.6 Hz, 2H, isobutylphenyl H-3, H-5), 7.56 (d,
J = 15.2 Hz, 1H, COCH = CH), 7.67 (d, J = 3.2 Hz, 1H,
thienyl H-3), 7.77 (d, J = 4.8 Hz, 1H, thienyl H-5), 7.91 (d,
J = 15.2 Hz, 1H, COCH = CH), 8.01 (d, J = 7.6 Hz, 2H,
isobutylphenyl H-2, H-6); 13C NMR (DMSO-d6) d 22.5,
30.0, 44.9, 120.8, 128.7, 129.1, 129.8, 130.7, 133.1, 135.7,
136.8, 140.2, 147.4, 188.5; MS (m/z): 270 (M?., 100 %), 192
(100 %); Anal. Calcd for C17H18OS: C, 75.51; H, 6.71.
Found: C, 75.68; H, 6.49.
Materials and methods
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 and 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. Microanalysis was performed
for C, H, N at the micro analytical center, Cairo University,
Egypt and was within 0.4 % of theoretical values. All
other reagents, purchased from the Acros Chemical Com-
pany, were used without further purification; 11a (Ro-
magnoli et al. 2009), 11b (Fun et al. 2008), 11c,d (Gupta
and Kaskhedikar 2012), 11e,f (Zheng et al. 2011), 11g–
j (Amutha and Nagarajan 2012) and 12 (Abdellatif et al.
2010) were prepared according to reported procedures.
General procedure for preparation of 1,3,5-triaryl-4,5-
dihydro-1H-pyrazoles (13a–l)
To a solution of the appropriate chalcone 11a–l (2.0 mmol)
in ethanol (20 mL), 4-hydrazinobenzenesulfonamide hy-
drochloride (12, 2.4 mmol, 0.535 g) was added and the
reaction mixture was refluxed for 12–18 h. The reaction
was monitored every 60 min interval on TLC plates using
chloroform/methanol (9.5:0.5 V/V). After completion of
the reaction, the mixture was poured into ice cold water.
The obtained solid was filtered, washed with water, dried
and crystallized from ethyl acetate to give the respective
pyrazoles 13a–l. Physical and spectral data for 13a–l are
listed below.
General method for preparation of 1,3-diarylprop-2-en-1-
ones (11k,l)
4-isobutylacetophenone (9b, 2.0 mmol, 0.352 g) and the
appropriate hetero aromatic aldehyde 10e or 10f (2.0 m-
mol) were dissolved in methanol (10 mL). An aqueous
solution of sodium hydroxide (5 % w/v, 5 mL) was added
123

K. R. A. Abdellatif et al.
1-(4-Aminosulfonylphenyl)-3-(4-nitrophenyl)-5-(phenyl)-4,
5-dihydro-1H-pyrazole (13a) Yield: 85 %; mp
1-(4-Aminosulfonylphenyl)-5-(4-fluorophenyl)-3-(4-nitro-
phenyl)-4,5-dihydro-1H-pyrazole (13d) Yield: 77 %;
mp 180–182 °C; IR (KBr): 3420 (NH2, broad), 2916 (CH
aliphatic), 1592 (C=N), 1333, 1151 (SO2); 1H NMR
(DMSO-d6) d 3.27 (dd, J = 17.6, 4.4 Hz, 1H, pyrazole
H-4), 4.02 (dd, J = 17.6, 12 Hz, 1H, pyrazole H0-4), 5.80
(dd, J = 12, 4.4 Hz, 1H, pyrazole H-5), 7.10 (s, 2H, NH2,
D2O exchangeable), 7.17 (d, J = 8.8 Hz, 2H, aminosul-
fonylphenyl H-2, H-6), 7.32 (m, 4H, fluorophenyl H-2,
H-3, H-5, H-6), 7.63 (d, J = 8.8 Hz, 2H, aminosul-
fonylphenyl H-3, H-5), 8.01 (d, J = 8.4 Hz, nitrophenyl
H-2, H-6), 8.28 (d, J = 8.4 Hz, 2H, nitrophenyl H-3, H-5);
13C NMR (DMSO-d6) d 42.7, 62.7, 113.2, 116.2, 116.5,
124.3, 127.1, 127.6, 128.21, 128.29, 137.5, 138.2, 145.7,
147.4, 148.1; EIMS: m/z (%): 440 (M?., 46), 83 (100);
Anal. Calcd for C21H17FN4O4S: C, 57.27; H, 3.89; N,
12.72. Found: C, 57.51; H, 3.94; N, 12.97.
200–202 °C; IR (KBr): 3397 (NH2), 2922 (CH aliphatic),
1
1590 (C=N), 1354, 1149 (SO2); H NMR (DMSO-d6) d
3.27 (dd, J = 17.6, 4.8 Hz, 1H, pyrazole H-4), 4.03 (dd,
J = 17.6, 12 Hz, 1H, pyrazole H0-4), 5.77 (dd, J = 12,
4.8 Hz, 1H, pyrazole H-5), 7.08 (s, 2H, NH2, D2O ex-
changeable), 7.16 (d, J = 8.4 Hz, 2H, aminosulfonylphenyl
H-2, H-6), 7.27 (d, J = 6.8 Hz, 2H, phenyl H-2, H-6), 7.36 (t,
J = 6.8 Hz, 3H, phenyl H-3, H-4, H-5), 7.62 (d, J = 8.4 Hz,
aminosulfonylphenyl H-3, H-5), 8.01 (d, J = 8.4 Hz, 2H,
nitrophenyl H-2, H-6), 8.28 (d, J = 8.4 Hz,2H, nitrophenyl
H-3, H-5); 13C NMR (DMSO-d6) d 42.8, 63.4, 113.1, 124.4,
126.1, 127.2, 127.6, 128.4, 129.7, 133.9, 138.4, 141.4, 145.7,
147.4, 148.1; EIMS: m/z (%): 422 (M?., 40), 80 (100); Anal.
Calcd for C21H18N4O4S: C, 59.70; H, 4.29; N, 13.26. Found:
C, 59.33; H, 3.95; N, 13.00.
1-(4-Aminosulfonylphenyl)-5-(4-methylphenyl)-3-(4-nitrophenyl)
-4,5-dihydro-1H-pyrazole (13b) Yield: 90 %; mp
223–225 °C; IR (KBr): 3433, 3332 (NH2), 2919 (CH
1-(4-Aminosulfonylphenyl)-5-(fur-2-yl)-3-(4-nitrophenyl)-
4,5-dihydro-1H-pyrazole (13e) Yield: 75 %; mp
220–222 °C; IR (KBr): 3362, 3269 (NH2), 1590 (C=N),
1340, 1153 (SO2); 1H NMR (DMSO-d6) d 3.27 (dd,
J = 17.6, 4.4 Hz, 1H, pyrazole H-4), 4.02 (dd, J = 17.6,
12 Hz, 1H, pyrazole H0-4), 5.80 (dd, J = 12, 4.4 Hz, 1H,
pyrazole H-5), 6.39 (dd, J = 3.3, 1.8 Hz, 1H, furyl H-4),
6.54 (d, J = 3.3 Hz, 1H, furyl H-5), 7.08 (s, 2H, NH2, D2O
exchangeable), 7.3 (d, J = 9 Hz, 2H, aminosulfonylphenyl
H-2, H-6), 7.55 (d, J = 0.9 Hz, 1H, furyl H-3), 7.66 (d,
J = 9 Hz, 2H, aminosulfonylphenyl H-3, H-5), 8.03 (d,
J = 8.7 Hz, nitrophenyl H-2, H-6), 8.29 (d, J = 8.7 Hz, 2H,
nitrophenyl H-3, H-5); 13C NMR (DMSO-d6) d 39.0, 57.0,
109.1, 110.9, 113.3, 124.4, 127.2, 127.5, 134.9, 138.4, 143.7,
145.6, 147.5, 148.3, 152.3; EIMS: m/z (%): 412 (M?, 21),
106 (100); Anal. Calcd for C19H16N4O5S: C, 55.33; H, 3.91;
N, 13.58. Found: C, 55.47; H, 3.98; N, 13.69.
1
aliphatic), 1587 (C=N), 1327 and 1154 (SO2); H NMR
(DMSO-d6) d 2.24 (s, 3H, CH3) 3.22 (dd, J = 17.6, 4.8 Hz,
1H, pyrazole H-4), 3.99 (dd, J = 17.6, 12.4 Hz, 1H, pyrazole
H0-4), 5.71 (dd, J = 12.4, 4.8 Hz, 1H, pyrazole H-5), 7.09 (s,
2H, NH2, D2O exchangeable), 7.15(m, 4H, methylphenyl H-2,
H-3, H-5, H-6), 7.17 (d, J = 8.8 Hz, 2H, aminosulfonylphenyl
H-2, H-6), 7.63(d,J = 8.8 Hz, 2H, aminosulfonylphenyl H-3,
H-5), 7.99 (d, J = 8.4 Hz, nitrophenyl H-2, H-6), 8.26 (d,
J = 8.4 Hz, 2H, nitrophenylH-3,H-5);13C NMR (DMSO-d6)
d 20.8, 42.6, 63.1, 113.1, 124.3, 125.9, 126.9, 127.5, 130.1,
133.3, 137.9, 138.2, 145.8, 147.2, 148.0; EIMS: m/z (%): 436
(M?, 100); Anal. Calcd for C22H20N4O4S: C, 60.54; H, 4.62;
N, 12.84. Found: C, 60.19; H, 4.35; N, 12.59.
1-(4-Aminosulfonylphenyl)-5-(4-chlorophenyl)-3-(4-nitro-
phenyl)-4,5-dihydro-1H-pyrazole (13c) Yield: 78 %; mp
233–235 °C; IR (KBr): 3426, 3347 (NH2), 2919 (CH
aliphatic), 1585 (C=N), 1331, 1155 (SO2); 1H NMR (DMSO-
d6) d 3.28 (dd, J = 17.6, 4.8 Hz, 1H, pyrazole H-4), 4.03 (dd,
J = 17.6, 12.4 Hz, 1H, pyrazole H0-4), 5.80 (dd, J = 12.4,
4.8 Hz, 1H, pyrazole H-5), 7.09 (s, 2H, NH2, D2O ex-
changeable), 7.16 (d, J = 8.8 Hz, 2H, aminosulfonylphenyl
H-2, H-6), 7.29 (d, J = 8.4 Hz, 2H, chlorophenyl H-2, H-6),
7.42 (d, J = 8.4 Hz, 2H, chlorophenyl H-3, H-5), 7.63 (d,
J = 8.8 Hz, 2H, aminosulfonylphenyl H-3, H-5), 8.01 (d,
J = 8.4 Hz, nitrophenyl H-2, H-6), 8.28 (d, J = 8.4 Hz, 2H,
nitrophenyl H-3, H-5); 13C NMR (DMSO-d6) d 42.6, 62.7,
113.1, 124.4, 127.3, 127.6, 128.2, 129.6, 132.8, 134.2, 138.3,
140.4, 145.5, 147.5, 148.1; EIMS: m/z (%): 456 (M?., 100);
Anal. Calcd for C21H17ClN4O4S: C, 55.20; H, 3.75; N,
12.26. Found: C, 55.01; H, 3.43; N, 12.37.
1-(4-Aminosulfonylphenyl)-5-(thien-2-yl)-3-(4-nitrophenyl)-
4,5-dihydro-1H-pyrazole
(13f) Yield:
85 %;
mp
208–210 °C; IR (KBr): 3396, 3282 (NH2), 1590 (C=N),
1323, 1154 (SO2); 1H NMR (DMSO-d6) d 3.43 (dd,
J = 17.6, 4.4 Hz, 1H, pyrazole H-4), 3.99 (dd, J = 17.6,
12.4 Hz, 1H, pyrazole H0-4), 6.16 (dd, J = 12.4, 4.4 Hz,
1H, pyrazole H-5), 6.96 (dd, J = 4.4, 3.2 Hz, 1H, thienyl
H-4), 7.15 (s, 2H, NH2, D2O exchangeable), 7.19 (d,
J = 3.2 Hz, 1H, thienyl H-3), 7.28 (d, J = 8.4 Hz, 2H,
minosulfonylphenyl H-2, H-6), 7.40 (d, J = 4.8, 1H,
thienyl H-5), 7.67 (d, J = 8.4 Hz, 2H, aminosul-
fonylphenyl H-3, H-5), 8.03 (d, J = 8.4 Hz, nitrophenyl
H-2, H-6), 8.29 (d, J = 8.4 Hz, 2H, nitrophenyl H-3, H-5);
13C NMR (DMSO-d6) d 42.9, 59.4, 113.5, 124.4, 126.2,
126.3, 127.2, 127.5, 134.3, 138.2, 144.1, 145.7, 147.5,
148.3; EIMS: m/z (%): 428 (M?, 32), 106 (100); Anal.
123

Synthesis and anti-inflammatory evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole…
Calcd for C19H16N4O4S2: C, 53.26; H, 3.76; N, 13.08.
Found: C, 53.43; H, 3.80; N, 13.21.
(dd, J = 11.6, 4.4 Hz, 1H, pyrazole H-5), 7.02 (s, 2H,
NH2, D2O exchangeable), 7.06 (d, J = 8.4 Hz, 2H,
aminosulfonylphenyl H-2, H-6), 7.24 (d, J = 7.6 Hz, 2H,
isobutylphenyl H-3, H-5), 7.27 (d, J = 8 Hz, 2H, chlor-
ophenyl H-2, H-6), 7.41 (d, J = 8 Hz, 2H, chlorophenyl
H-3, H-5) 7.59 (d, J = 8.4 Hz, 2H, aminosulfonylphenyl
H-3, H-5), 7.70 (d, J = 7.6 Hz, 2H, isobutylphenyl H-2,
H-6); 13C NMR (DMSO-d6) d 22.4, 29.9, 43.2, 44.7, 62.0,
112.4, 117.7, 126.3, 127.6, 128.0, 129.5, 129.8, 132.7,
140.8, 143.5, 146.3, 150.4; EIMS: m/z (%): 467 (M?, 60),
468 (M?1, 22), 469 (M?2, 24), 64 (100 %); Anal. Calcd for
C25H26ClN3O2S: C, 64.16; H, 5.60; N, 8.98. Found: C,
64.50; H, 5.39; N, 9.09.
1-(4-Aminosulfonylphenyl)-3-(4-isobutylphenyl)-5-(phenyl)-
4,5-dihydro-1H-pyrazole
(13g) Yield:
108–110 °C; IR (KBr): 3382, 3267 (NH2), 2954, 2923 (CH
aliphatic), 1591 (C=N), 1331 and 1156 (SO2); H NMR
80 %;
mp
1
(DMSO-d6) d 0.87 (d, J = 6.4 Hz, 6H, CH2CH(CH3)2),
1.85 (m, 1H, CH2CH(CH3)2), 2.46 (d, J = 7.2 Hz, 2H,
CH2CH(CH3)2), 3.17 (dd, J = 17.6, 4.4 Hz, 1H, pyrazole
H-4), 3.96 (dd, J = 17.6, 11.6 Hz, 1H, pyrazole H0-4), 5.62
(dd, J = 11.6, 4.4 Hz, 1H, pyrazole H-5), 7.02 (s, 2H,
NH2, D2O exchangeable), 7.06 (d, J = 8.4 Hz, 2H,
aminosulfonylphenyl H-2, H-6), 7.25 (m, 5H, phenyl H-2,
H-3, H-4, H-5, H-6), 7.33 (d, J = 7.6 Hz, 2H, iso-
butylphenyl H-3, H-5), 7.58 (d, J = 8.4 Hz, 2H,
aminosulfonylphenyl H-3, H-5), 7.70 (d, J = 7.6 Hz, 2H,
isobutylphenyl H-2, H-6); 13C NMR (DMSO-d6) d 22.4,
30.0, 43.0, 44.7, 62.1, 112.4, 124.7, 126.4, 127.5, 127.7,
129.2, 129.8, 133.1, 143.6, 146.2, 147.3, 149.4, 150.4;
EIMS: m/z (%): 433 (M?., 58), 64 (100); Anal. Calcd for
C25H27N3O2S: C, 69.26; H, 6.28; N, 9.69. Found: C, 68.97;
H, 6.39; N, 9.51.
1-(4-Aminosulfonylphenyl)-5-(4-fluorophenyl)-3-(4-isobutyl-
phenyl)-4,5-dihydro-1H-pyrazole (13j) Yield: 76 %; mp
148–150 °C; IR (KBr): 3381, 3261 (NH2), 3073 (CH aro-
matic), 2956, 2871 (CH aliphatic), 1595 (C=N), 1333, 1157
1
(SO2); H NMR (DMSO-d6) d 0.89 (d, J = 6.4 Hz, 6H,
CH2CH(CH3)2), 1.85 (m, 1H, CH2CH(CH3)2), 2.47 (d,
J = 7.2 Hz, 2H, CH2CH(CH3)2), 3.17 (dd, J = 17.6,
4.8 Hz, 1H, pyrazole H-4), 3.95 (dd, J = 17.6, 11.6 Hz,
1H, pyrazole H0-4), 5.65 (dd, J = 11.6, 4.8 Hz, 1H, pyra-
zole H-5), 7.04 (s, 2H, NH2, D2O exchangeable), 7.06 (d,
J = 8.4 Hz, 2H, aminosulfonylphenyl H-2, H-6), 7.17 (t,
J = 8.4 Hz, 2H, fluorophenyl H-3, H-5),7.24 (d, J = 8 Hz,
2H, isobutylphenyl H-3, H-5), 7.29 (d, J = 8.4 Hz, 2H,
fluorophenyl H-2, H-6), 7.59 (d, J = 8.4 Hz, 2H,
aminosulfonylphenyl H-3, H-5), 7.70 (d, J = 8 Hz, 2H,
isobutylphenyl H-2, H-6); 13C NMR (DMSO-d6) d 22.4,
29.9, 43.3, 44.7, 61.9, 112.3, 116.1, 116.4, 126.3, 127.6,
128.1, 129.8, 132.6, 143.5, 146.4, 150.4, 160.6, 163.0;
EIMS: m/z (%): 451 (M?, 32), 80 (100); Anal. Calcd for
C25H26FN3O2S: C, 66.50; H, 5.80; N, 9.31. Found: C,
66.34; H, 5.80; N, 9.35.
1-(4-Aminosulfonylphenyl)-3-(4-isobutylphenyl)-5-(4-methyl-
phenyl)-4,5-dihydro-1H-pyrazole (13h) Yield: 75 %; mp
140–142 °C; IR (KBr): 3396, 3267 (NH2), 2953, 2919 (CH
aliphatic), 1592 (C=N), 1330, 1154 (SO2); 1H NMR
(DMSO-d6) d 0.87 (d, J = 6.4 Hz, 6H, CH2CH(CH3)2),
1.85 (m, 1H, CH2CH(CH3)2), 2.24 (s, 3H, CH3), 2.50 (d,
J = 7.2 Hz, 2H, CH2CH(CH3)2),3.13 (dd, J = 17.6,
4.4 Hz, 1H, pyrazole H-4), 3.92 (dd, J = 17.6, 11.6 Hz,
1H, pyrazole H0-4), 5.57 (dd, J = 11.6, 4.4 Hz, 1H, pyra-
zole H-5), 7.01 (s, 2H, NH2, D2O exchangeable), 7.05 (d,
J = 8.4 Hz, 2H, aminosulfonylphenyl H-2, H-6), 7.13 (m,
4H, methylphenyl H-2, H-3, H-5, H-6), 7.23 (d,
J = 7.6 Hz, 2H, isobutylphenyl H-3, H-5), 7.57 (d,
J = 8.4 Hz, 2H, aminosulfonylphenyl H-3, H-5), 7.69 (d,
J = 7.6 Hz, 2H, isobutylphenyl H-2, H-6); 13C NMR
(DMSO-d6) d 20.9, 22.4, 29.9, 43.4, 44.7, 62.4, 112.3,
125.9, 126.2, 127.5, 129.5, 129.8, 130.0, 132.3, 137.5,
138.8, 143.4, 146.5, 150.4; EIMS: m/z (%): 447 (M?, 32),
64 (100); Anal. Calcd for C26H29N3O2S: C, 69.77; H, 6.53;
N, 9.39. Found: C, 69.94; H, 6.69; N, 9.47.
1-(4-Aminosulfonylphenyl)-5-(fur-2-yl)-3-(4-isobutylphenyl)-
4,5-dihydro-1H-pyrazole
(13k) Yield:
95 %;
mp
140–142 °C; IR (KBr): 3381, 3260 (NH2), 2954, 2923(CH
aliphatic), 1591 (C=N), 1329, 1155 (SO2); 1H NMR
(DMSO-d6) d 0.89 (d, J = 6.4 Hz, 6H, CH2CH(CH3)2),
1.85 (m, 1H, CH2CH(CH3)2), 2.47 (d, J = 7.2 Hz, 2H,
CH2CH(CH3)2), 3.17 (dd, J = 17.6, 4.8 Hz, 1H, pyrazole
H-4), 3.95 (dd, J = 17.6, 11.6 Hz, 1H, pyrazole H0-4), 5.65
(dd, J = 11.6, 4.8 Hz, 1H, pyrazole H-5), 6.38 (dd,
J = 3.4, 1.8 Hz, 1H, furyl H-4), 6.48 (d, J = 3.4 Hz, 1H,
furyl H-5), 7.07 (s, 2H, NH2, D2O exchangeable), 7.20 (d,
J = 8.4 Hz, 2H, aminosulfonylphenyl H-2, H-6), 7.25 (d,
J = 7.6 Hz, 2H, isobutylphenyl H-3, H-5), 7.55 (d,
J = 1.8 Hz, 1H, furyl H-3), 7.63 (d, J = 8.4 Hz, 2H,
aminosulfonylphenyl H-3, H-5), 7.72 (d, J = 7.6 Hz, 2H,
isobutylphenyl H-2, H-6); 13C NMR (DMSO-d6) d 22.5,
30.0, 39.3, 44.8, 56.2, 108.6, 110.8, 112.5, 126.4, 127.5,
1-(4-Aminosulfonylphenyl)-5-(4-chlorophenyl)-3-(4-isobutyl-
phenyl)-4,5-dihydro-1H-pyrazole (13i) Yield: 85 %; mp
110–112 °C; IR (KBr): 3381, 3263 (NH2), 2952 (CH
aliphatic), 1591 (C=N), 1326, 1152 (SO2); 1H NMR
(DMSO-d6) d 0.87 (d, J = 6.4 Hz, 6H, CH2CH(CH3)2),
1.85 (m, 1H, CH2CH(CH3)2), 2.49 (d, J = 7.2 Hz, 2H,
CH2CH(CH3)2), 3.18 (dd, J = 17.6, 4.4 Hz, 1H, pyrazole
H-4), 3.95 (dd, J = 17.6, 11.6 Hz, 1H, pyrazole H0-4), 5.65
123

K. R. A. Abdellatif et al.
128.7, 129.7, 133.6, 143.2, 143.4, 146.5, 150.4, 152.8;
EIMS: m/z (%): 423 (M?, 41), 106 (100); Anal. Calcd for
C23H25N3O3S: C, 65.23; H, 5.95; N, 9.92. Found: C, 65.58;
H, 5.69; N, 10.06.
treatments were performed according to protocols ap-
proved by the Research Ethical Committee of Faculty of
Pharmacy Beni-Suef University (2014-Beni-Suef, Egypt).
Formalin induced rat paw edema
1-(4-Aminosulfonylphenyl)-3-(4-isobutylphenyl)-5-(thien-2-
yl)-4,5-dihydro-1H-pyrazole (13l) Yield: 80 %; mp
120–122 °C; IR (KBr): 3365, 3261 (NH2), 3101 (CH aro-
matic), 2954, 2919 (CH aliphatic), 1590 (C=N), 1329, 1155
Anti-inflammatory activity study for the prepared com-
pounds 13a–l was determined in vivo by conducting the
standard formalin-induced paw edema method in rats
(Turner 1965). Wister albino rats were divided into forty
groups of five animals each. Thickness of the left hind paw
of each rat was measured in millimeters using plethyso-
mometer, before any drug administration for each rat (0 h).
The first group was kept as a negative control given 10 %
aqueous solution of DMSO (v/v). The second, third and
fourth groups were orally administered celecoxib as a
reference standard in three different doses, one dose for
each group, to calculate ED50. The rest groups were treated
orally with the tested compounds 13a–l, three groups for
each compound, in the form of 10 % aqueous solution of
DMSO. Each compound was administered in three differ-
ent concentrations ranging from 20 to 200 mg/kg body
weight to calculate ED50 for each compound and treatment
began 1 h before induction of inflammation. Induction of
paw edema was performed by subcutaneous injection of
2.5 % of formalin (0.1 mL/rat) into the right hind paw of
each rat. Paw thickness of each rat was measured after 3 h
of formalin injection using plethysomometer.
1
(SO2); H NMR (DMSO-d6) d 0.88 (d, J = 6.4 Hz, 6H,
CH2CH(CH3)2), 1.86 (m, 1H, CH2CH(CH3)2), 2.46 (d,
J = 7.2 Hz, 2H, CH2CH(CH3)2), 3.32 (dd, J = 18, 4.4 Hz,
1H, pyrazole H-4), 3.92 (dd, J = 17.6, 11.6 Hz, 1H,
pyrazole H0-4), 5.99 (dd, J = 11.6, 4.4 Hz, 1H, pyrazole
H-5), 6.95 (dd, J = 4.8, 3.6 Hz, 1H, thienyl H-4), 7.06 (s,
2H, NH2, D2O exchangeable), 7.15 (d, J = 3.6 Hz, 1H,
thienyl H-3), 7.19 (d, J = 8.8 Hz, 2H, aminosul-
fonylphenyl H-2, H-6), 7.25 (d, J = 8.0 Hz, 2H, iso-
butylphenyl H-3, H-5), 7.38 (d, J = 4.8 Hz, thienyl H-5),
7.62 (d, J = 8.8 Hz, 2H, aminosulfonylphenyl H-3, H-5),
7.72 (d, J = 8.0 Hz, 2H, isobutylphenyl H-2, H-6); 13C
NMR (DMSO-d6) d 22.5, 30.0, 43.5, 44.8, 58.8, 112.8,
125.9, 126.0, 126.4, 127.4, 127.5, 129.5, 129.8, 133.3,
143.5, 144.8, 146.6, 150.7; EIMS: m/z (%): 439 (M?., 54),
64 (100); Anal. Calcd for C23H25N3O2S2: C, 62.84; H,
5.73; N, 9.56. Found: C, 62.61; H, 5.37; N, 9.25.
Biological evaluation
COX-1/COX-2 inhibition colorimetric assay
Ulcerogenic liability
The ability of the tested compounds to inhibit COX-1/
COX-2 was measured using colorimetric COX (ovine)
Inhibitor Screening Assay Kit (Kit catalog number 760111,
Cayman Chemical, Ann Arbor, MI, USA) according to the
manufacturer’s instructions and as mentioned before (Ab-
delazeem et al. 2014). Different concentrations of tested
compounds or celecoxib were incubated with the enzymes
for a period of 5 min at 25 °C. After the incubation period
and the addition of colorimetric substrate and arachidonic
acid, the absorbance was measured at 590 nm using plate
reader.
The ulcerogenic effect of 13a–l as well as celecoxib was
evaluated according to Meshali’s method (Hassan et al.
2014). Seventy adult male albino rats were used in this
study and divided into 14 groups. The animals were al-
lowed to fast for 18 h before the administration of the drug.
The first group received 10 % aqueous solution of DMSO
(v/v) and served as a control group. The second group
received celecoxib as a reference drug in a dose of
50 mg/kg. The other groups received the prepared com-
pounds 13a–l in a dose of 50 mg/kg. After 2 h of admin-
istration of drug animals were fed. Rats were given the
required dose orally for three successive days. After 2 h of
the last given dose, rats were sacrificed; the stomach of
each rat was removed then opened along the greater cur-
vature and rinsed with sodium chloride 0.9 %. In order to
examine the stomach, it was stretched by pins on a cork-
board. With the aid of a magnifying lens (10 xs) ulcers and
erosions were searched in the stretched stomach. Calcula-
tion of the ulcer index was done according to Robert’s
method (Hassan et al. 2014). The expression of the degree
of ulcerogenic effect was in term of dividing the percentage
incidence of ulcers in each group of animal by ten, the
Anti-inflammatory activity
Animals
Adult male Wister albino rats (125–150 g) were used
throughout the study of anti-inflammatory activity and ul-
cerogenic liabilities. The animals (five per cage) were kept
at controlled conditions (temperature 23 2 °C, humidity
60 10 %) and a 12/12 h light/dark cycle with access to
food and water. All procedures relating to animal care and
123

Synthesis and anti-inflammatory evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole…
1
average number of ulcers per stomach and the visual ob-
servation of the ulcer score (average severity of ulcer). The
ulcer scores are divided into 0 ulcer score which indicates
no ulcer, 1 ulcer score which indicates only mucosal ery-
thema, 2 ulcer score which indicates mild mucosal edema,
slight bleeding or slight erosions, 3 ulcer score which
indicates moderate edema, bleeding ulcers or erosions and
4 ulcer index which indicates severe ulceration, erosions,
edema and tissue necrosis. The sum of all above values
indicates the ulcer index.
corresponding to SO2 while, the H NMR spectra of 13a-
l showed three signals as doublet of doublet (dd), each of
one proton intensity, one at d 3.13–3.43, second at d
3.92–4.03, and the third at d 5.57–6.16 corresponding to
two protons at position 4 and one proton at position 5,
respectively of the dihydropyrazole ring. Each proton has
two J values, the two protons at position 4 have higher
J value (17.6 Hz) indicating coupling between each other
and lower J values indicating coupling of each one of them
with the proton at position 5. Accordingly, proton at po-
sition 5 has two J values indicating it’s coupling with the
two protons at position 4. Additionally, 13C NMR spectra
of 13a–l confirmed the presence of the dihydropyrazole
ring due to presence of three peaks at d 39.0–44.8,
56.2–63.4 and 148.0–163.0 corresponding to dihydropyra-
zole C-4, C-5 and C-3, respectively.
Statistical analysis
Significant difference among groups was assessed using
one way ANOVA followed by Dunnett’stest. The results
were expressed as mean standard deviation (SD). Dif-
ferences were considered significant at *P \ 0.05, and
**P \ 0.01, respectively.
Biological evaluation
In vitro cyclooxygenase (COX) inhibition assay
Results and discussion
Chemistry
In order to study the biological activity of the target com-
pounds 13a–l, we tested their ability to inhibit both ovine
COX-1 and COX-2 isozymes. The efficacies of tested
compounds were determined through using a concentration
causing 50 % enzyme inhibition (IC50) (Table 1). The re-
sults revealed that the potency of the tested compounds 13a–
l are ranging from potent to moderately potent of the in-
hibitory activity for COX-1 (IC50 = 3.6–19.8 lM) and
COX-2 (IC50 = 0.84–6.8 lM). Out of the twelve dihy-
dropyrazole series, 13f, 13j, 13l and 13k showed more in-
hibitory activity towards both COX-1 (IC50 = 3.6, 3.7, 4.2
and 5.1 lM, respectively) and COX-2 (IC50 = 0.84, 0.93,
0.98 and 1.15 lM, respectively) than celecoxib (IC50 = 9.7
and 1.33 lM for COX-1 and COX-2, respectively). Addi-
tionally, they had moderate COX-2 selectivity index (COX-
2 SI = 4.28, 3.97, 4.28 and 4.43) compared to reference drug
celecoxib (COX-2 SI = 7.2). On the other hand, the other
eight tested compounds showed a moderate inhibitory ac-
tivity against both COX-1 and COX-2 in the following order
13b [ 13i [ 13a [ 13e [ 13c [ 13d [ 13g [ 13h com-
pared to celecoxib.
A group of 3-(4-isobutyl(nitro)phenyl)-5-(substituted aryl)-
1-(4-sulphamoylphenyl) 4,5-dihydro-1H-pyrazoles (13a–
l) were synthesized using the reaction sequence illustrated
in Scheme 1. Accordingly, the reaction of 4-substituted
acetophenone (9a,b) with different aldehydes 10a–f at
room temperature in methanol provided the corresponding
chalcones 11a–l in high yields (70–95 %). Cyclization of
the chalcones 11a–l with 4-hydrazinobenzenesulfonamide
hydrochloride (12) in refluxing ethanol afforded the target
pyrazole derivatives 13a–l in good yields (75–95 %). All
the newly synthesized compounds have been characterized
1
by IR, H NMR, 13C NMR, mass spectra and elemental
analyses.
The IR spectra of chalcone compounds 11k,l showed
sharp peak at 1656–1648 cm-1 corresponding to C=O
1
while, the H NMR spectra of 11 k,l displayed two dou-
blets, each of one proton intensity, one at d 7.55–7.56 and
the second at d 7.85–7.91 with high J value (15.2 Hz)
indicating the 2 olefinic protons. 13C NMR spectra of 11k,l
confirmed also the presence of a, b-unsaturated carbonyl
system of chalcones by presence of three peaks at d
128.6–133.1, 129.6–140.2 and 188.4–188.5 corresponding
to propenone C-3, propenone C-2 and C-1 of C=O
respectively.
Anti-inflammatory activity
Anti-inflammatory activity of compounds 13a–l was
evaluated by performing the standard formalin-induced
foot paw edema method in rats using celecoxib as a ref-
erence drug (Turner 1965). ED50 of each compound de-
termined after 3 h are depicted in (Table 2). ED50 of
compounds 13f, 13j, 13k and 13l which showed the best
The IR spectra of dihydropyrazole compounds 13a–
l showed either a broad or forked peak at 3433–3260 cm-1
corresponding to NH2 in addition to two sharp peaks, one
at 1157–1149 cm-1 and the second at 1354–1323 cm-1
123

K. R. A. Abdellatif et al.
Scheme 1 Reagents and
conditions: a MeOH, NaOH,
RT, 12 h. b EtOH, reflux,
12–18 h
cyclooxygenase activities indicated their weak anti-in-
flammatory activities (ED50 = 118, 68, 90 and 117 mg/kg,
respectively) compared to celecoxib (ED50 = 18 mg/kg).
While compounds 13i, 13e and 13h showed moderate
in vitro cyclooxygenase activities, their ED50 indicated that
they had the best anti-inflammatory activities of all com-
pounds (ED50 = 18, 32 and 36 mg/kg, respectively) com-
pared to celecoxib (ED50 = 18 mg/kg).
Table 1 In vitro COX-1 and COX-2 inhibition and anti-inflamma-
tory activity of dihydropyrazoles 13a–l and celecoxib
Compound no.
IC50 (lM)a
COX-1
COX-2
COX-2 selectivity indexb
13a
13b
13c
13d
13e
13f
12.4
8.9
3.4
3.64
4.04
3.17
3.44
3.63
4.28
3.35
3.13
3.89
3.97
4.43
4.28
7.29
2.2
14.6
17.9
13.8
3.6
4.6
5.2
Ulcerogenic liability
3.8
0.84
5.9
The ulcerogenic potential of compounds 13a–l (50 mg/kg)
was evaluated according to Meshali’s method and the ulcer
index was calculated according to Robert’s method (Hassan
et al. 2014).The ulcerogenic effect was compared to cele-
coxib (50 mg/kg). From the data obtained, (Table 3), it had
been observed that compounds 13d, 13l and 13i caused less
gastric ulceration effect (ulcer index of compound 13d: 2.7;
13l: 2.7; 13i: 2.8) in the experimental animals, compared to
the standard drug celecoxib (ulcer index 3.35). Also, it had
been noted that compounds 13b, 13h, 13e and 13k have a
gastric safety profile very close to celecoxib (ulcer index of
compound 13b: 3.97; 13h: 3.7; 13e: 3.95; 13k: 3.97).
13g
13h
13i
19.8
21.3
10.9
3.7
6.8
2.8
13j
0.93
1.15
0.98
1.33
13k
13l
5.1
4.2
Celecoxib
9.7
a
IC50 value represents the compound concentration that is required
to produce 50 % inhibition of COX-1 or COX-2 which is the mean
value of two determinations where the deviation from the mean is
\10 % of the mean value
b
Selectivty index (COX-1 IC50/COX-2 IC50
)
123

Synthesis and anti-inflammatory evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole…
Table 2 The anti-inflammatory
18 mg/kg) although in case of thiophene 13f, it had COX-
Compound no. ED50 (mg/kg)
3 h
activity (ED50, mg/kg) of
dihydropyrazoles 13a–l and
celecoxib after 3 h against
formalin-induced paw edema in
rats
1 IC50 = 3.6 and COX-2 IC50 = 0.84 lM less than
celecoxib (IC50 = 0.87 lM for COX-2 and 6.7 lM for
COX-1). In addition, in 4-isobutylphenyl compounds
13g–l the introduction of small hetero aryl group, furan
13k or thiophene 13l, in position 5 of pyrazoline ring
decreases the anti-inflammatory activity (ED50 = 90,
117 mg/kg for 13k and 13l, respectively) compared to
celecoxib (ED50 = 18 mg/kg) although they both had
COX-1 IC50 = 5.1, 4.2 lM respectively and COX-2
IC50 = 1.15, 0.98 lM, respectively less than celecoxib
(IC50 = 0.87 lM for COX-2 and 6.7 lM for COX-1). In
addition, compound 13 l has an improved gastric safety
profile (13l ulcer index = 2.7) compared to celecoxib
(ulcer index = 3.35). Moreover, in case of 4-iso-
butylphenyl compounds 13g–l the introduction of
4-fluorophenyl 13h or 4-chlorophenyl 13i exhibited anti-
inflammatory activity ranging from moderate (13h
ED50 = 36 mg/kg) to strong (13i ED50 = 24 mg/kg)
compared to celecoxib (ED50 = 18 mg/kg) with gastric
safety profile ranging from comparable (13h ulcer in-
dex = 3.7) to better (13i ulcer index = 2.8) than cele-
coxib (ulcer index = 3.35). In conclusion, in our trials to
synthesize celecoxib like compounds the in vitro and
in vivo structure activity relationship acquired suggest
that the replacement of pyrazole, trifluoromethyl and tolyl
group in celecoxib with dihydropyrazole, 4-iso-
butylphenyl and 4-chlorophenyl respectively in compound
13i almost retain the anti-inflammatory activity compared
to celecoxib but with improved gastric safety profile and
moderate COX-2 selectivity index compared to celecoxib.
Consequently, the previous compounds provide us with
new scaffolds for the development of novel compounds
having in vivo anti-inflammatory activity comparable to
celecoxib but with improved gastric safety profile.
13a
13b
13c
65
45
54
13d
13e
54
32
13f
118
90
13g
13h
13i
36
24
13j
68
13k
13l
90
117
18
Celecoxib
Conclusion
In summary, the present study reported the design and
synthesis of novel celecoxib analogues. The synthesized
compounds were evaluated for their COX-1/COX2 ac-
tivity in vitro, anti-inflammatory activity in vivo and
ulcerogenic liability. COX-1 and COX-2 studies declared
that all compounds 13a–l showed selectivity towards
COX-2 more than COX-1 due to presence of SO2NH2
moiety which is essential for COX-2 selectivity. Structure
activity relationship showed that in 4-nitrophenyl
compounds 13a–f the introduction of small hetero aryl
group, furan 13e or thiophene 13f, in position 5 of
pyrazoline ring showed anti-inflammatory activity ranging
from weak (13f ED50 = 118 mg/kg) to moderate
(13e ED50 = 32 mg/kg) compared to celecoxib (ED50
=
Table 3 Ulcerogenic effect of
dihydropyrazoles 13a–l and
celecoxib in rats (50 mg/kg)
Compound
Average severity
Average no of ulcers
% Incidence/10
Ulcer index
13a
0.67 0.013
0.67 0.013
0.62 0.012
0.5 0.007
0.75 0.024
0.5 0.003
0.75 0.0014
0. 0.5 0.002
0.5 0.004
0.83 0.004
0.67 0.008
0.5 0.008
0.63 0.022
0
0.4 0.005
0.3 0.004
0.4 0.005
0.2 0.003
0.2 0.004
0.4 0.003
0.3 0.006
0.2 0.005
0.3 0.008
0.4 0.002
0.3 0.001
0.2 0.001
0.72 0.016
0
3
3
4
2
3
4
3
3
2
4
3
2
2
0
4.07
3.97
5.02
2.7
13b
13c
13d
13e
3.95
4.9
13f
13g
4.05
3.7
13h
13i
2.8
13j
5.23
3.97
2.7
13k
13l
Celecoxib
DMSO
3.35
0
123

K. R. A. Abdellatif et al.
Chandra, T., N. Garg, S. Lata, K.K. Saxena, and A. Kumar. 2010.
Synthesis of substituted acridinyl pyrazoline derivatives and
their evaluation for anti-inflammatory activity. European Jour-
nal of Medicinal Chemistry 45: 1772–1776.
References
Abdelazeem, A.H., S.A. Abdelatef, M.T. El-Saadi, H.A. Omar, S.I.
Khan, C.R. McCurdy, and S.M. El-Moghazy. 2014. Novel
pyrazolopyrimidine derivatives targeting COXs and iNOS
enzymes; design, synthesis and biological evaluation as potential
anti-inflammatory agents. European Journal of Pharmaceutical
Sciences 62: 197–211.
Abdellatif, K.R.A., M.A. Chowdhury, and E.E. Knaus. 2008a.
Synthesis of new 1-[4-methane (amino) sulfonylphenyl)]-5-[4-
(aminophenyl)]-3-trifluoromethyl-1H-pyrazoles. Journal of
Heterocyclic Chemistry 45: 1707–1710.
Chowdhury, M.A., K.R.A. Abdellatif, Y. Dong, D. Das, M.R. Suresh,
and E.E. Knaus. 2008a. Synthesis of celecoxib analogs that
possess a N-hydroxypyrid-2(1H)one 5-lipoxygenase pharma-
cophore: biological evaluation as dual inhibitors of cyclooxyge-
nases and 5-lipoxygenase with anti-inflammatory activity.
Bioorganic & Medicinal Chemistry Letters 18: 6138–6141.
Chowdhury, M.A., K.R.A. Abdellatif, Y. Dong, and E.E. Knaus.
2008b. 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.
Bioorganic & Medicinal Chemistry 16: 8882–8888.
´
Abdellatif, K.R.A., M.A. Chowdhury, C.A. Velazquez, Z. Huang, Y.
Dong, D. Das, G. Yu, M.R. Suresh, and E.E. Knaus. 2010.
Celecoxib prodrugs possessing a diazen-1-ium-1,2-diolate nitric
oxide donor moiety: synthesis, biological evaluation and nitric
oxide release studies. Bioorganic & Medicinal Chemistry Letters
20: 4544–4549.
´
Dogne, J.M., C.T. Supuran, and D. Pratico. 2005. Adverse cardio-
vascular effects of the coxibs. Journal of Medicinal Chemistry
48: 2251–2257.
Fioravanti, R., A. Bolasco, F. Manna, F. Rossi, F. Orallo, F. Ortuso, S.
Alcaro, and R. Cirilli. 2010. Synthesis and biological evaluation
of N-substituted-3,5-diphenyl-2-pyrazoline derivatives as cy-
clooxygenase (COX-2) inhibitors. European Journal of Medic-
inal Chemistry 45: 6135–6138.
Fun, H.K., S. Chantrapromma, P.S. Patil, E.D. D’Silva, and S.M.
Dharmaprakash. 2008. (E)-3-(4-methyl-phen-yl)-1-(4-nitro-phe-
nyl)prop-2-en-1-one. Acta Crystallographica Section E, Struc-
ture Reports Online 64: o954–o955.
Gupta, R.A., and S.G. Kaskhedikar. 2012. Synthesis, antitubercular
activity, and QSAR analysis of substituted nitroaryl analogs:
Chalcone, pyrazole, isoxazole, and pyrimidines. Medicinal
Chemistry Research 22: 3863–3880.
Abdellatif, K.R.A., M.A. Chowdhury, Y. Dong, D. Das, G. Yu, C.
´
Velazquez, M.R. Suresh, and E.E. Knaus. 2009. Diazen-1-ium-
1,2-diolated nitric oxide donor ester prodrugs of 5-(4-car-
boxymethylphenyl)-1-(4-methanesulfonylphenyl)-3-tri-
fluoromethyl-1H-pyrazole and its aminosulfonyl analog:
Synthesis, biological evaluation and nitric oxide release studies.
Bioorganic & medicinal chemistry 17: 5182–5188.
Abdellatif, K.R.A., M.A. Chowdhury, Y. Dong, and E.E. Knaus.
2008b. Diazen-1-ium-1,2-diolated nitric oxide donor ester pro-
drugs of 1-(4-methanesulfonylphenyl)-5-aryl-1H-pyrazol-3-car-
boxylic acids: synthesis, nitric oxide release studies and anti-
inflammatory activities. Bioorganic & medicinal chemistry 16:
6528–6534.
Habeeb, A.G., P.N.P. Rao, and E.E. Knaus. 2001. Design and
synthesis of celecoxib and rofecoxib analogues as selective
cyclooxygenase-2 (COX-2) Inhibitors: Replacement of sulfon-
amide and methylsulfonyl pharmacophores by an azido bioisos-
tere. Journal of Medicinal Chemistry 44: 3039–3042.
Hassan, G.S., S.M. Abou-Seri, G. Kamel, and M.M. Ali. 2014.
Celecoxib analogs bearing benzofuran moiety as cyclooxyge-
nase-2 inhibitors: Design, synthesis and evaluation as potential
anti-inflammatory agents. European Journal of Medicinal
Chemistry 76: 482–493.
Johnson, M., B.Younglove, L. Lee, R. LeBlanc, H.H. Jr., P. Hills, H.
Mackay, T. Brown, S.L. Mooberry, and M. Lee. 2007. Design,
synthesis, and biological testing of pyrazoline derivatives of combre-
tastatin-A4. Bioorganic & medicinal chemistry letters 17: 5897–901.
Khode, S., V. Maddi, P. Aragade, M. Palkar, P.K. Ronad, S.
Mamledesai, A.H.M. Thippeswamy, and D. Satyanarayana.
2009. Synthesis and pharmacological evaluation of a novel
series of 5-(substituted)aryl-3-(3-coumarinyl)-1-phenyl-2-pyra-
zolines as novel anti-inflammatory and analgesic agents. Euro-
pean Journal of Medicinal Chemistry 44: 1682–1688.
Lange, J.H.M., H.H.V. Stuivenberg, W. Veerman, H.C. Wals, B.
Stork, H.K.A.C. Coolen, A.C. McCreary, T.J.P. Adolfs, and C.G.
Kruse. 2005. Novel 3,4-diarylpyrazolines as potent cannabinoid
CB1 receptor antagonists with lower lipophilicity. Bioorganic &
Medicinal Chemistry Letters 15: 4794–4798.
´
Abdellatif, K.R.A., M.A. Chowdhury, Y. Dong, C. Velazquez, D.
Das, M.R. Suresh, and E.E. Knaus. 2008c. Diazen-1-ium-1,2-
diolated nitric oxide donor ester prodrugs of 5-(4-hydrox-
ymethylphenyl)-1-(4-aminosulfonylphenyl)-3-trifluoromethyl-
1H-pyrazole and its methanesulfonyl analog: synthesis, biologi-
cal evaluation and nitric oxide release studies. Bioorganic &
Medicinal Chemistry 16: 9694–9698.
¨
¨
Ahlstrom, M.M., M. Redderstrom, I. Zamora, and K. Luthman. 2007.
CYP2C9 structure–metabolism relationships: Optimizing the
metabolic stability of COX-2 inhibitors. Journal of Medicinal
Chemistry 50: 4444–4452.
Ahn, J.H., H.M. Kim, S.H. Jung, S.K. Kang, K.R. Kim, S.D. Rhee,
S.D. Yang, H.G. Cheon, and S.S. Kim. 2004. Synthesis and DP-
IV inhibition of cyano-pyrazoline derivatives as potent anti-
diabetic agents. Bioorganic & Medicinal Chemistry Letters 14:
4461–4465.
Al-Hourani, B.J., S.K. Sharma, J.Y. Mane, J. Tuszynski, V. Baracos,
T. Kniess, M. Suresh, J. Pietzsch, and F. Wuest. 2011. Synthesis
and evaluation of 1,5-diaryl-substituted tetrazoles as novel
selective cyclooxygenase-2 (COX-2) inhibitors. Bioorganic &
Medicinal Chemistry Letters 21: 1823–1826.
Amutha, P., and S. Nagarajan. 2012. Synthesis and antimicrobial
activities of new 4,6-diaryl-4,5-dihydro-3-hydroxy-2H-inda-
zoles. Journal of Heterocyclic Chemistry 49: 428–432.
Bano, S., K. Javed, S. Ahmad, I.G. Rathish, S. Singh, and M.S. Alam.
2011. Synthesis and biological evaluation of some new 2-pyra-
zolines bearing benzene sulfonamide moiety as potential anti-
inflammatory and anti-cancer agents. European Journal of
Medicinal Chemistry 46: 5763–5768.
Ovais, S., R. Bashir, S. Yaseen, P. Rathore, M. Samim, and K. Javed.
2012. Synthesis and pharmacological evaluation of some novel
2-pyrazolines bearing benzenesulfonamide as anti-inflammatory
and blood glucose lowering agents. Medicinal Chemistry
Research 22: 1378–1385.
Ovais, S., S. Yaseen, R. Bashir, P. Rathore, M. Samim, S. Singh, V.
Nair, and K. Javed. 2013. Synthesis and anti-inflammatory
activity of celecoxib like compounds. Journal of Enzyme
Inhibition and Medicinal Chemistry 28: 1105–1112.
Bashir, R., S. Ovais, S. Yaseen, H. Hamid, M.S. Alam, M. Samim, S.
Singh, and K. Javed. 2011. Synthesis of some new 1,3,5-
trisubstituted pyrazolines bearing benzene sulfonamide as anti-
cancer and anti-inflammatory agents. Bioorganic & Medicinal
Chemistry Letters 21: 4301–4305.
123

Synthesis and anti-inflammatory evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole…
Rathish, I.G., K. Javed, S. Ahmad, S. Bano, M.S. Alam, K.K. Pillai, S.
Singh, and V. Bagchi. 2009. Synthesis and antiinflammatory
activity of some new 1,3,5-trisubstituted pyrazolines bearing
benzene sulfonamide. Bioorganic & Medicinal Chemistry Let-
ters 19: 255–258.
Turner, R.A. 1965. Screening method in pharmacology. Anti-inflam-
matory agent 13, 158. New York: Academic Press.
Zarghi, A., L. Najafnia, B. Daraee, O.G. Dadrass, and M. Hedayati.
2007. Synthesis of 2,3-diaryl-1,3-thiazolidine-4-one derivatives
as selective cyclooxygenase (COX-2) inhibitors. Bioorganic &
Medicinal Chemistry Letters 17: 5634–5637.
Zarghi, A., T. Zebardast, B. Daraie, and M. Hedayati. 2009. Design
and synthesis of new 1,3-benzthiazinan-4-one derivatives as
selective cyclooxygenase (COX-2) inhibitors. Bioorganic &
Medicinal Chemistry 17: 5369–5373.
Zebardast, T., A. Zarghi, B. Daraie, M. Hedayati, and O.G. Dadrass.
2009. Design and synthesis of 3-alkyl-2-aryl-1,3-thiazinan-4-one
derivatives as selective cyclooxygenase (COX-2) inhibitors.
Bioorganic & Medicinal Chemistry Letters 19: 3162–3165.
Zheng, C.J., S.M. Jiang, Z.H. Chen, B.J. Ye, and H.R. Piao. 2011.
Synthesis and anti-bacterial activity of some heterocyclic
chalcone derivatives bearing thiofuran, furan, and quinoline
moieties. Archiv der Pharmazie 344: 689–695.
Romagnoli, R., P.G. Baraldi, M.D. Carrion, O. Cruz-Lopez, C.L.
Cara, J. Balzarini, E. Hamel, A. Canella, E. Fabbri, R. Gambari,
G. Basso, and G. Viola. 2009. Hybrid alpha-bromoacryloylami-
do chalcones. Design, synthesis and biological evaluation.
Bioorganic & Medicinal Chemistry Letters 19: 2022–2028.
Rostom, S.A.F.2006. Synthesisandinvitroantitumorevaluationofsome
indeno[1,2-c]pyrazol(in)es substituted with sulfonamide, sulfony-
lurea(-thiourea) pharmacophores, and some derived thiazole ring
systems. Bioorganic & Medicinal Chemistry 14: 6475–6485.
Sahu, S.K., M. Banerjee, A. Samantray, C. Behera, and M.A. Azam.
2008. Synthesis, analgesic, anti-inflammatory and antimicrobial
activities of some novel pyrazoline derivatives. Tropical Journal
of Pharmaceutical Research 7: 961–968.
Scheen, A.J. 2004. Withdrawal of rofecoxib (Vioxx): what about
cardiovascular safety of COX-2 selective non-steroidal anti-
inflammatory drugs. Revue Medicale de Liege 59: 565–569.
123