Design, synthesis and pharmacological evaluation of novel azole derivatives of aryl acetic acid as anti-inflammatory and analgesic agents

Article abstract of DOI:10.3109/14756366.2010.481622

A series of substituted azole derivatives (3a-e, 4a-e and 5a-e) were synthesised by the cyclisation of N¹(diphenylethanoyl)-N ⁴-substituted phenyl thiosemicarbazides under various reaction conditions. These compounds were tested in v

Full text of DOI:10.3109/14756366.2010.481622

Journal of Enzyme Inhibition and Medicinal Chemistry, 2011; 26(1): 141–148
Copyright © 2011 Informa UK, Ltd.
ISSN 1475-6366 print/ISSN 1475-6374 online
DOI: 10.3109/14756366.2010.481622
RESEARCH ARTICLE
Design, synthesis and pharmacological evaluation of novel
azole derivatives of aryl acetic acid as anti-inflammatory and
analgesic agents
Mohammad Amir, Khalid Saifullah, and Wasim Akhter
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hamdard University, New Delhi, India
Abstract
A series of substituted azole derivatives (3a–e, 4a–e and 5a–e) were synthesised by the cyclisation of
N1(diphenylethanoyl)-N4-substitutedphenylthiosemicarbazidesundervariousreactionconditions.Thesecompounds
were tested in vivo for their anti-inflammatory activity. The compounds which showed activity comparable to
the standard drug ibuprofen, were screened for their analgesic, ulcerogenic and lipid peroxidation activities. The
compounds 5-(diphenylmethyl)-N-(4-fluorophenyl)-1,3,4-oxadiazol-2-amine (3b) and 5-(diphenylmethyl)-N-(3-
chloro-4-fluorophenyl)-1,3,4-oxadiazol-2-amine (3c) emerged as the most active compounds of the series, and were
moderately more potent than the standard drug, ibuprofen. (This abstract was published in Inflammation Research,
Supplement 2, Volume 56, page A101, 2008.)
Keywords: Diphenyl acetic acids, anti-inflammatory, analgesic, acute ulcerogenicity, lipid peroxidation
Introduction
which regulate normal cell activity. e second isoform
COX-2, in contrast, is induced in inflammatory cells in
response to pro-inflammatory stimuli such as cytokines,
tumour promoting agents, and bacterial endotoxins. e
prostaglandins (PGs) produced by COX-2 play a major
role in inflammatory reactions and are responsible for
the characteristic inflammatory symptoms [6]. ese
findings stimulated the development of selective COX-2
inhibitors (coxibs) as a new generation of NSAIDs, free
from GI toxicity [7,8]. Unfortunately careful prospective
examination of coxibs has revealed unexpected cardio-
vascular adverse effects [9]. erefore the development
of novel compounds having anti-inflammatory and
analgesic activity with an improved safety profile is still
a necessity. Studies have shown that derivatisation of the
carboxylate function of arylalkonic acids resulted in a
retained anti-inflammatory activity and reduced ulcero-
genic potential [10–13]. Furthermore it has been reported
in the literature that the substituted azole derivatives
such as 1,3,4-oxadiazole/thiadiazole [14,15] and 1,2,4 tri-
azole [16] possess significant anti-inflammatory activity.
Nonsteroidal anti-inflammatory drugs (NSAIDs) includ-
ing aspirin, are among the most widely prescribed drugs
worldwide. rough their anti-inflammatory, antipyretic
and analgesic activities, they represent a choice treat-
ment in various inflammatory diseases, so as to relieve
the aches and pains of every day life. Chronic NSAID
therapy effectively reduces the symptoms of many pain-
ful arthritic syndromes, but there can be adverse gas-
trointestinal (GI) complications ranging from stomach
irritation to life threatening GI ulceration and bleeding.
Long term NSAID therapy makes NSAID induced GI tox-
icity a substantial patient risk, and a costly healthcare and
societal burden in terms of the associated hospitalisation
and morbidity [1]. NSAIDs exert their anti-inflammatory
effect mainly through inhibition of the cyclooxygenases
(COXs), as the key enzymes in prostaglandin (PG) bio-
synthesis from arachidonic acid [2–4]. ere are at least
two mammalian COX isoforms, COX-1 and COX-2 [5].
COX-1 is the constitutive isoform, which performs a
housekeeping function to synthesise prostaglandins,
Address for Correspondence: Mohammed Amir, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hamdard University, New
Delhi, India. Tel: 91-11-26059878; Fax: 91-11-26059688; E–mail: mamir_s2003@yahoo.co.in
(Received 20 August 2009; revised 28 October 2009; accepted 10 November 2009)
141

142
Mohammed Amir et al.
In view of these observations and in continuation of our
research programme on the synthesis of five membered
heterocyclic compounds [17–19], we report here the syn-
thesis of some new azole derivatives of diphenyl acetic
acid. e synthesised compounds have been found to
possess an interesting profile of anti-inflammatory and
analgesic activity, with a significant reduction in their
ulcerogenic effect (Scheme 1).
Anal. Calcd for C21H17FN2OS: C, 69.21; H, 4.7; N, 7.69;
Found: C, 69.03; H, 4.52; N, 7.58%.
N1(Diphenylethanoyl)-N4-(3-chloro-4-flourophenyl)
thiosemicarbazide (2c)
Yield: 60%; mp: 165°C; IR (KBr, cm−1): 3307 (NH), 1686
(C=O), 1083 (C=S); 1H NMR (CDCl3) δ (ppm): 5.21 (s, 1H,
CH), 7.12–7.63 (m, 14H, ArH), 8.94 (bs, 1H, NH), 9.98 (bs,
1H, CSNH), 10.96 (bs, 1H, CONH); MS: m/z 398 (M+), 400
(M++2); Anal. Calcd for C21H17ClFN2OS: C, 63.23; H, 4.04;
N, 7.02; Found: C, 63.12; H, 3.89; N, 6.89%.
Materials and methods
Chemistry
All chemicals for synthesis were supplied by Merck
(Darmstadt, Germany) and S.D. Fine Chemicals (Delhi,
India). e melting points of the newly synthesised com-
pounds were determined in open glass capillary and are
uncorrected. IR (KBr) spectra were recorded on a Nicolet
5PC (MA, USA) FTIR spectrophotometer (υmax in cm−1) and
1H NMR spectra were recorded on a Brucker Model - 400
NMR (Fallanden, Switzerland) spectrometer in CDCl3 and
DMSO-d6 using tetramethysilane (TMS) as the internal
reference (chemical shifts in δ ppm). 13C NMR spectra
were measured on Bruker - 400 instrument (100MHz) with
complete proton decoupling. Chemical shifts are reported
in ppm downfield from tetramethylsilane (TMS). Mass
spectra were recorded on a Jeol SX- 102/DA-6000 (Tokyo,
Japan) spectrometer. e purity of the compounds was
checked on silica gel G plates using iodine vapours as the
visualising agent.
N1(Diphenylethanoyl)-N4-(4-methylphenyl)thiosemicarbazide
(2d)
Yield: 80%; mp: 185°C; IR (KBr, cm−1): 3274 (NH), 1654
1
(C=O), 1079 (C=S); H NMR (CDCl3) δ (ppm): 5.86 (s, 1H,
CH), 6.3–7.41 (m, 14H, ArH), 8.86 (bs. 1H, NH), 9.87 (bs
1H, CSNH), 10.75 (bs, 1H, CONH); MS: m/z 398 (M+); Anal.
Calcd for C22H20N2OS: C, 73.30, H, 5.59, N, 7.77; Found: C,
73.21; H, 5.42; N, 7.68%.
N1(Diphenylethanoyl)-N4-(4-methoxyphenyl)
thiosemicarbazide (2e)
Yield: 78%; mp: 190°C; IR (KBr, cm−1): 3265 (NH), 1674
(C=O), 1091 (C=S); 1H NMR (CDCl3) δ (ppm): 3.68 (s, 3H,
OCH3), 5.8 (s, 1H, CH), 6.87–7.43 (m, 14H, ArH), 8.81 (bs,
1H, NH), 9.83 (bs, 1H, CSNH), 10.21 (bs, 1H, CONH); MS:
m/z 376 (M+); Anal. Calcd for C22H20N2O2S: C, 70.19; H,
5.35; N, 7.44; Found: C, 70.03; H, 5.19; N, 7.31%.
Synthesis of diphenyl acetic acid hydrazide (1)
Compound 1 was prepared by the procedure given in the
literature. [14]
General method for synthesis of 5-(diphenylmethyl)-2-(4-
substituted phenyl)amino-1,3,4-oxadiazoles (3a–e)
A suspension of thiosemicarbazide (0.002 moles) in etha-
nol (50mL) was dissolved in sodium hydroxide (5N, 1mL)
with cooling and stirring resulting in the formation of a
clear solution. To this iodine, in potassium iodide solu-
tion (5%, 10mL), was added drop wise with stirring till the
colour of the iodine persisted at room temperature. e
reaction mixture was then refluxed for 3h on a water bath.
It was then concentrated, cooled, the solid was separated
out, filtered, dried and recrystallised with ethanol.
Synthesis of N1(diphenylethanoyl)-N4-aryl thiosemicarbazides
(2a–e)
A mixture of diphenyl acetic acid hydrazide (0.1M), aryl
isothiocyanate (0.1M) and ethanol (50mL) was placed in a
100mLroundbottomflaskandrefluxedfor3–4honawater
bath. It was then concentrated, cooled and kept overnight
in a refrigerator. e solid was separated out, then filtered,
dried and recrystallised from a suitable solvent.
5-(Diphenylmethyl)-2-(4-chlorophenyl)amino-1,3,4-
oxadiazole (3a)
N1(Diphenylethanoyl)-N4-(4-chlorophenyl)thiosemicarbazide
(2a)
Yield: 71%, mp: 142°C; IR (KBr, cm−1): 3330 (NH), 1615
1
Yield: 70%; mp: 148°C; IR (KBr, cm−1): 3280 (NH), 1676
(C=O), 1079 (C=S); 1H NMR (CDCl3) δ (ppm): 5.09 (s, 1H,
CH), 6.9–7.35 (m, 14H, ArH), 8.83 (bs, 1H, NH), 9.9 (bs
1H, CSNH), 10.83 (bs, 1H, CONH); MS: m/z 380 (M+), 382
(M++2); Anal. Calcd for C21H17ClN2OS: C, 66.22; H, 4.5; N,
7.35; Found: C, 66.08; H, 4.32; N, 7.12%.
(C=N), 1226 (C-O-C); H NMR (CDCl3) δ (ppm): 5.61 (s,
1H, CH), 6.93–7.31 (m, 14H, ArH), 7.91 (s, 1H, NH); 13C
NMR (CDCl3) δ (ppm): 45.32 (CH), 121.13 (2CHarom),
127.38 (4CHarom), 127.71 (4CHarom), 128.76 (2CHarom),
130.17 (2CHarom), 132.47 (CHarom), 134.31 (CHarom), 137.17
(2CHarom), 158.37 (C5/arom), 159.13 (C2/arom); MS: m/z 362
(M+), 364 (M++2); Anal. Calcd for C21H16ClN3O: C, 69.71; H,
4.46; N, 11.61; Found: C, 69.86; H, 4.32; N, 11.73%.
N1(Diphenylethanoyl)-N4-(4-flourophenyl)
thiosemicarbazide(2b)
Yield: 65%; mp: 162°C; IR (KBr, cm−1): 3289 (NH), 1682
(C=O), 1091 (C=S); 1H NMR (CDCl3) δ (ppm): 5.13 (s, 1H,
CH), 6.97–7.48 (m, 14H, ArH), 8.87 (bs, 1H, NH), 9.93 (bs,
1H, CSNH), 10.89 (bs, 1H, CONH); MS: m/z 364 (M+);
5-(Diphenylmethyl)-2-(4-fluorophenyl)amino-1,3,4-
oxadiazole (3b)
Yield: 65.8%, mp: 145°C; IR (KBr, cm−1): 3342 (NH), 1610
1
(C=N), 1221 (C-O-C); H NMR (CDCl3) δ (ppm): 5.64 (s,
Journal of Enzyme Inhibition and Medicinal Chemistry

Design, synthesis and pharmacological evaluation of novel azole derivatives
143
O
O
NH
2
N
H
OH
CH
i) Abs. EtOH, H SO
CH
2
4
ii) NH NH .H O
2
2
2
R
O
(1)
H
N
NCS
N
H
C
CH
R
EtOH
S
(2a-e)
Polyphosphoric acid
EtOH
4N NaOH
EtOH
NaOH
KI/I
2
N
N
N
N
N
N
H
C
H
C
NH
NH
S
O
HC
N
SH
R
R
R
(5a-e)
(4a-e)
(3a-e)
R = a: 4-Cl; b: 4-F; c: 3-Cl-4-F; d: 4-CH ; e: 4-OCH
3
3
Scheme 1. Synthesis of azole derivatives 3, 4 and 5.
1H, CH), 6.99–7.37 (m, 14H, ArH), 7.95 (s, 1H, NH); 13C
NMR (CDCl3) δ (ppm): 47.24 (CH), 117.16 (2CHarom),
118.27 (2CHarom), 128.83 (2CHarom), 130.29 (4CHarom), 130.52
(4CHarom),137.59(CHarom),140.31(2CHarom),155.38(CHarom),
159.87 (C5/arom), 160.59 (C2/arom);MS: m/z 345 (M+); Anal.
Calcd for C21H16FN3O: C, 73.03; H, 4.67; N, 12.17; Found: C,
73.21; H, 4.53; N, 11.98%.
128.81 (4CHarom), 129.86 (2CHarom), 132.65 (CHarom), 135.02
(CHarom), 138.52 (2CHarom), 160.49 (C5/arom), 160.79 (C2/
arom); MS: m/z 341 (M+); Anal. Calcd for C22H19N3O:
C, 77.40; H, 5.61; N, 12.31; Found: C, 77.29; H, 5.53; N,
12.24%.
5-(Diphenylmethyl)-2-(4-methoxyphenyl)amino-1,3,4-
oxadiazole (3e)
Yield: 80%, mp: 175°C; IR (KBr, cm−1): 3318 (NH), 1620
5-(Diphenylmethyl)-2-(3-chloro-4-fluorophenyl)amino-1,3,4-
oxadiazole (3c)
1
(C=N), 1231 (C-O-C); H NMR (CDCl3) δ (ppm): 3.81 (s,
Yield: 66.9%; mp: 170°C; IR (KBr, cm−1): 3314 (NH), 1625
(C=N), 1246 (C-O-C); 1H NMR (CDCl3) δ (ppm): 5.68
(s, 1H, CH), 7.16–7.47 (m, 14H, ArH), 8.1 (s, 1H, NH);
13C NMR (CDCl3) δ (ppm): 43.52 (CH), 111.53 (CHarom),
111.75 (CHarom), 114.07 (CHarom), 115.66 (CHarom), 122.66
(2CHarom), 123.65 (4CHarom), 123.9 (4CHarom), 130.77
(CHarom), 133.66 (2CHarom), 149.43 (CHarom), 155.48
(C5/arom), 155.65 (C2/arom); MS: m/z 379 (M+), 381 (M++2);
Anal. Calcd for C21H15ClFN3O: C, 66.41; H, 3.98; N, 11.06;
Found: C, 66.73; H, 3.87; N, 10.93%.
3H, OCH3), 5.59 (s, 1H, CH), 6.98–7.33 (m, 14H, ArH),
7.52 (s, 1H, NH); 13C NMR (CDCl3) δ (ppm): 47.84 (CH),
55.12 (OCH3), 113.36 (2CHarom), 125.17 (CHarom), 126.26
(2CHarom), 127.91 (4CHarom), 128.13 (4CHarom), 129.27
(2CHarom), 137.48 (2CHarom), 152.71 (C5/arom), 159.39
(C2/arom), 167.58 (CHarom); MS: m/z 357 (M+); Anal. Calcd
for C22H19N3O2: C, 73.93; H, 5.36; N, 11.76; Found: C, 73.78;
H, 5.14; N, 11.83%.
General method for synthesis of 5-(diphenylmethyl)-4-(4-
substituted phenyl)-3-mercapto (4H)-1,2,4-triazoles (4a–e)
In a 100 ml round bottom flask, thiosemicarbazide
(0.001 M) and ethanol (20 mL) was placed. To it sodium
hydroxide solution (4N, 2 mL) was added, resulting in the
formation of a clear solution. e reaction mixture was
refluxed for 6 h on a water bath, concentrated, cooled and
filtered. e pH of the filtrate was adjusted to between
pH 5–6 with acetic acid and kept aside for 1–2h. e solid
5-(Diphenylmethyl)-2-(4-methylphenyl)amino-1,3,4-
oxadiazole (3d)
Yield: 75%, mp: 180°C; IR (KBr, cm−1): 3310 (NH), 1612
1
(C=N), 1228 (C-O-C); H NMR (CDCl3) δ (ppm): 2.3 (s,
3H, CH3), 5.63 (s, 1H, CH), 7.1–7.36 (m, 14H, ArH), 7.57
(s, 1H, NH); 13C NMR (CDCl3) δ (ppm): 20.75 (CH3), 48.51
(CH), 117.55 (2CHarom), 127.59 (2CHarom), 128.62 (4CHarom),
© 2011 Informa UK, Ltd.

144
Mohammed Amir et al.
obtained was separated, then filtered, washed with water,
dried and recrystallised from ethanol.
114.65 (2CHarom), 126.01 (CHarom), 127.44 (2CHarom),
128.63 (4CHarom), 128.76 (4CHarom), 129.58 (2CHarom), 138.8
(2CHarom), 153.56 (C5/arom), 160.16 (C3/arom), 168.7 (CHarom);
MS: m/z 373 (M+); Anal. Calcd for C22H19N3OS: C, 70.75;
H, 5.13; N, 11.25; Found: C, 70.59; H, 5.27; N, 11.13%.
5-(Diphenylmethyl)-4-(4-chlorophenyl)-3-mercapto(4H)-
1,2,4-triazole (4a)
Yield: 74%; mp 225°C; IR (KBr, cm−1): 2550 (SH), 1610
(C=N); 1H NMR (CDCl3) δ (ppm): 5.03 (s, 1H, CH), 6.94–
7.39 (m, 14H, ArH), 11.49 (bs, 1H, SH); 13C NMR (CDCl3)
δ (ppm): 48.5 (CH), 127.4 (2CHarom), 128.51 (4CHarom),
128.73 (4CHarom), 129.58 (2CHarom), 129.65 (2CHarom),
131.92 (CHarom), 135.61 (CHarom), 138.15 (2CHarom), 152.87
(C5/arom), 168.46 (C3/arom); MS: m/z 378 (M+), 380 (M++2);
Anal. Calcd for C21H16ClN3S: C, 66.75; H, 4.27; N, 11.12;
Found: C, 66.89; H, 4.16; N, 10.98%.
General method for synthesis of 5-(diphenylmethyl)-2-(4-
substituted phenyl)amino-1,3,4-thiadiazoles (5a–e)
e thiosemicarbazide (0.001 M) was added gradually
with stirring to polyphosphoric acid (12–15 mL) at 120°C
for 20 min. e reaction mixture was heated with stirring
for another 3 h and poured over crushed ice. e pre-
cipitated mass was filtered, washed with water, dried and
recrystallised from methanol.
5-(Diphenylmethyl)-2-(4-chlorophenyl)amino-1,3,4-
thiadiazole (5a)
5-(Diphenylmethyl)-4-(4-fluorophenyl)-3-mercapto (4H)-
1,2,4-triazole (4b)
Yield: 75%; mp: 115°C; IR (KBr, cm−1): 3388 (NH), 1636
(C=N); 1H NMR (CDCl3) δ (ppm): 5.61 (s, 1H, CH), 7.25–
7.87 (m, 14H, ArH), 7.97 (s, 1H, NH); 13C NMR (CDCl3)
δ (ppm): 51.47 (CH), 116.46 (2CHarom), 116.78 (2CHarom),
127.92 (2CHarom), 129.35 (4CHarom), 129.57 (4CHarom),
137.76 (CHarom), 142.35 (2CHarom), 156.68 (CHarom), 162.47
(C5/arom), 165.37 (C2/arom); MS: m/z 378 (M+), 380 (M++2);
Anal. Calcd for C21H16ClN3S: C, 66.75; H, 4.27; N, 11.12;
Found: C, 66.58; H, 4.12; N, 11.29%.
Yield: 70%; mp: 245°C; IR (KBr, cm−1): 2680 (SH), 1588
(C=N); 1H NMR (CDCl3) δ (ppm): 5.12 (s, 1H, CH), 6.97–
7.45 (m, 14H, ArH), 11.53 (bs, 1H, SH); 13C NMR (CDCl3)
δ (ppm): 47.89 (CH), 118.37 (2CHarom), 119.69 (2CHarom),
128.73 (2CHarom), 131.25 (4CHarom), 131.86 (4CHarom),
136.67 (CHarom), 140.17 (2CHarom), 147.36 (CHarom), 152.63
(C5/arom), 168.25 (C3/arom); MS: m/z 361 (M+); Anal. Calcd
for C21H16FN3S: C, 69.78; H, 4.27; N, 11.63; Found: C, 69.64;
H, 4.16; N, 11.51%.
5-(Diphenylmethyl)-2-(4-fluorophenyl)amino-1,3,4-
thiadiazole (5b)
5-(Diphenylmethyl)-4-(3-chloro-4-flurophenyl)-3-mercapto
(4H)-1,2,4 triazole (4c)
Yield: 65.5%; mp: 132°C; IR (KBr, cm−1): 3346 (NH), 1632
(C=N); 1H NMR (CDCl3) δ (ppm): 5.67 (s, 1H, CH), 7.34–
7.91 (m, 14H, ArH), 8.03 (s, 1H, NH); 13C NMR (CDCl3)
δ (ppm) 51.28 (CH), 115.97 (2CHarom), 116.19 (2CHarom),
127.59 (2CHarom), 129.03 (4CHarom), 129.11 (4CHarom),
137.59 (CHarom), 141.99 (2CHarom), 156.46 (CHarom), 162.22
(C5/arom), 165.13 (C2/arom); MS: m/z 361 (M+); Anal. Calcd.
for C21H16FN3S: C, 69.78; H, 4.46; N, 11.63; Found: C, 69.59;
H, 4.37; N, 11.52%.
Yield: 62%; mp: 252°C; IR (KBr, cm−1): 2650 (SH), 1610
(C=N); 1H NMR (CDCl3) δ (ppm): 5.19 (s, 1H, CH), 7.09–
7.52 (m, 14H, ArH), 11.63 (bs, 1H, SH); 13C NMR (CDCl3)
δ (ppm): 45.47 (CH), 111.64 (CHarom), 111.95 (CHarom),
114.35 (CHarom), 115.98 (CHarom), 122.84 (2CHarom), 123.93
(4CHarom), 124.37 (4CHarom), 131.27 (CHarom), 133.98
(2CHarom), 149.76 (CHarom), 151.13 (C5/arom), 163.41
(C2/arom); MS: m/z 396 (M+), 398 (M++2); Anal. Calcd for
C21H15ClFN3S: C, 63.71; H, 3.82; N, 10.61; Found: C, 63.62;
H, 3.7; N, 10.52%.
5-(Diphenylmethyl)-2-(3-chloro-4-fluorophenyl)amino-1,3,4-
thiadiazole (5c)
5-(Diphenylmethyl)-4-(4-methylphenyl)-3-mercapto(4H)-
1,2,4-triazole (4d)
Yield: 58%; mp: 113°C; IR (KBr, cm−1): 3343 (NH), 1612
(C=N); 1H NMR (CDCl3), δ (ppm): 5.72 (s, 1H, CH), 7.41–
7.97 (m, 14H, ArH) 8.14 (s, 1H, NH); 13C NMR (CDCl3)
δ (ppm): 48.12 (CH), 112.35 (CHarom), 112.68 (CHarom),
115.63 (CHarom), 116.12 (CHarom), 123.59 (2CHarom),
124.54 (4CHarom), 124.97 (4CHarom), 132.32 (CHarom),
134.84 (2CHarom), 152.43 (CHarom), 161.57 (C5/arom), 165.21
(C2/arom); MS: m/z 396 (M+), 398 (M++2); Anal. Calcd for
C21H15ClFN3S: C, 63.71; H, 3.82; N, 10.61; Found: C, 63.56;
H, 3.71; N, 10.49%.
Yield:80%,mp:254°C;IR(KBr,cm−1):2564(SH),1623(C=N);
1H NMR (CDCl3) δ (ppm): 2.39 (s, 3H, CH3), 5.05 (s, 1H,
CH), 6.88–7.31 (m, 14H, ArH), 11.35 (bs, 1H, SH); 13C NMR
(CDCl3) δ (ppm): 20.63 (CH3), 48.42 (CH), 127.64 (2CHarom),
128.71 (4CHarom), 128.93 (4CHarom), 129.87 (2CHarom), 130.16
(2CHarom), 132.17 (CHarom), 135.84 (CHarom), 138.34 (2CHarom),
152.96(C5/arom), 168.75 (C3/arom); MS: m/z 357 (M+); Anal.
Calcd for C22H19N3S: C, 73.92; H, 5.36; N, 11.75; Found: C,
73.78; H, 5.24; N, 11.87%.
5-(Diphenylmethyl)-4-(4-methoxyphenyl)-3-mercapto(4H)-
1,2,4-triazole (4e)
5-(Diphenylmethyl)-2-(4-methylphenyl)amino-1,3,4-
thiadiazole (5d)
Yield: 81%, mp: 232°C; IR (KBr, cm−1): 2557 (SH), 1608
(C=N); 1H NMR (CDCl3) δ (ppm): 3.83 (s, 3H, OCH3), 5.05
(s, 1H, CH), 6.88–7.32 (m, 14H, ArH), 10.78 (bs, 1H, SH);
13C NMR (CDCl3) δ (ppm): 48.49 (CH), 55.57 (OCH3),
Yield: 75.6%, mp: 130°C; IR (KBr, cm−1): 3337 (NH), 1623
1
(C=N); H NMR (DMSO d6) δ (ppm): 2.29 (s, 3H, CH3),
5.62 (s, 1H, CH), 7.09–7.34 (m, 14H, ArH), 7.78 (s, 1H, NH);
13C NMR (DMSO d6) δ (ppm): 25.54 (CH3), 56.96 (CH),
Journal of Enzyme Inhibition and Medicinal Chemistry

Design, synthesis and pharmacological evaluation of novel azole derivatives
145
according to the formula: % anti-inflammatory activ-
ity = 100 × (1-Vt/Vc) where, Vt and Vc are the volume of
oedema for the test and control groups respectively.
122.88 (2CHarom), 132.05 (2CHarom), 133.46 (4CHarom), 133.5
(4CHarom), 134.3 (2CHarom), 136.43 (CHarom), 143.16 (CHarom),
146.07 (2CHarom), 166.28 (C5/arom), 170.32 (C2/arom); MS: m/z
357 (M+); Anal. Calcd for C22H19N3S: C, 73.92; H, 5.36; N,
11.75; Found: C, 73.74, H, 5.27; N, 11.59%.
Analgesic activity
Analgesic activity was evaluated by the tail immersion
method [21] using Swiss albino mice (25–30 g) of either
sex selected by a random sampling technique. e stan-
dard drug, ibuprofen and test compounds and standard
drugs were administered orally (70mg/kg body weight)
as a suspension using 0.5% w/v carboxymethyl cellulose
as a vehicle. e lower 5 cm portion of the tail was gen-
tly immersed into thermostatically controlled water at
55 0.5°C. e time for tail withdrawal from the water
(in seconds) was taken as the reaction time with a cut
of time of immersion, set at 10 seconds for both control
and treatment groups. e reaction time was measured
before and after a 4 h interval after the administration of
the test compounds and standard drugs.
5-(Diphenylmethyl)-2-(4-methoxyphenyl)amino-1,3,4-
thiadiazole (5e)
Yield: 80%; mp: 110°C; IR (KBr, cm−1 ): 3358 (NH), 1624
1
(C=N); H NMR (DMSO d6) δ (ppm): 3.81 (s, 3H, OCH3),
5.65(s, 1H, CH), 7.14–7.43(m, 14, 14ArH), 7.91(s, 1H, NH);
13C NMR (DMSO d6) δ (ppm): 54.27 (CH), 58.69 (OCH3),
118.68 (2CHarom), 129.65 (CHarom), 132.53 (2CHarom),
134.27 (4CHarom), 134.82 (4CHarom), 135.69 (2CHarom),
140.13 (2CHarom), 163.37 (C5/arom), 165.19 (C2/arom), 169.24
(CHarom); MS: m/z 373 (M+); Anal. Calcd for C22H19N3OS:
C, 70.75; H, 5.13; N, 11.25; Found: C, 70.63, H, 5.02; N,
11.13%.
Pharmacology
e synthesised compounds were evaluated for their
anti-inflammatory, analgesic, ulcerogenic and lipid-
peroxidation activities. e Wister rats and albino mice
used in the present study were housed and kept in accor-
dance with the Hamdard University Animal Care Unit,
which applies the guidelines and rules laid down by the
Committee for the Purpose of Control and Supervision
of Experiments on Animals (CPCSEA), Ministry of Social
Justice and Empowerment, Government of India. All the
test compounds and standard drug were administered in
the form of solution (0.5% w/v carboxymethyl cellulose
as a vehicle) by an oral route. Each group consisted of six
animals. All the animals were procured from the CPCSEA
and maintained in colony cages at 25 2°C, relative
humidity of 45–55%, under a 12h light and dark cycle and
were fed a standard animal feed. All the animals were
acclimatised for a week before use. e anti-inflamma-
tory activity of the test compounds were compared with
the control. e analgesic, ulcerogenic and lipid peroxi-
dation activities were compared with the standard drug
ibuprofen. Data were analysed by student’s t test for n=6.
Acute ulcerogenicity
An acute ulcerogenesis test was performed according to
Cioli et al. [22] using Wistar rats (180–200 gm) of either sex.
e animals were divided into groups, with each group
consisting of 6 rats. All the rats were fasted for 24h with
free access to water. e control groups of animals were
administered a 0.5% CMC solution intraperitoneally. One
group was administered with the standard drug ibuprofen
orally in a dose of 210mg/kg once a day for three days.
e remaining group of animals was administered with
the test compounds through the same route. e animals
were immediately fed and kept for 17 hrs after the dose
administration. After 17h they were killed and dissected
for the estimation of ulcerogenic activity. e stomach
was dissected out and washed with running water, opened
along the greater curvature and carefully observed with a
magnifying glass. e mucosal damage for each stomach
was assessed according to the following scoring system:
0.5: redness, 1: spot ulcers, 1.5: haemorrhagic streak,
2.0: ulcers >3 but ≤5, 3.0: ulcers >5. e mean score of
each treated group minus the mean score of the con-
trol group was regarded as the severity index of gastric
mucosal damage.
Anti-inflammatory activity
Anti-inflammatory activity was carried out by the carra-
geenan induced paw oedema test in the Wister albino rat
according to the method of Winter et al. [20]. e stan-
dard drug, ibuprofen and test compounds were given
orally (70mg/kg body weight) as a suspension using 0.5%
w/v carboxymethyl cellulose as a vehicle. After one hour,
foot paw oedema was induced by injecting 0.1ml of 1%
carrageenan subcutaneously into the planter portion of
the right hind paw of each rat. e initial paw volume
was measured immediately using a mercury plethys-
mometer. e paw volume was again measured after the
time intervals of 3 and 4 h. e percentage inhibition of
inflammation was calculated for the standard drugs and
other test compounds and a comparison was made. e
percentage inhibition of inflammation was calculated
Lipid peroxidation
e lipid peroxidation in the gastric mucosa was deter-
mined according to the method of Ohkawa et al [23].
After the evaluation of each stomach for ulcers, the gastric
mucosa of the glandular portion was scrapped, weighed
(100 mg), homogenised in a pestle and mortar and the
homogenate was prepared in 1.8 ml of ice cold 1.15 % KCl
solution. e homogenate was supplemented with 0.2 ml
of 8.1 % sodium dodecyl sulfate (SDS), 1.5 ml of acetate
buffer and 1.5 ml of 0.8 % thiobarbituric acid (TBA). e
mixture was incubated at 95°C for 60 minutes on a boiling
water bath then extracted with a mixture of n-butanol:
pyridine (15:1, v/v; 5 mL) by shaking vigorously for 1
minute and then kept in ice for 2 minutes. e organic
© 2011 Informa UK, Ltd.

146
Mohammed Amir et al.
layer of reaction mixture was centrifuged at 3000 rpm for
10 minutes and the absorbance was measured at 532 nm
on a UV spectrophotometer. e results were expressed
as nmol malondialdehyde /100 mg tissue.
singlet of the SH proton at δ 11.35. e mass spectrum of
the compound showed a molecular ion peak M+ at an m/z
of 357 corresponding to the molecular formula C27H19N3S.
e 5-(diphenylmethyl)-2-(4-substiued phenyl)amino-
1,3,4-thiadiazole (5a–e) were obtained by cyclisation of
2a–e with polyphosphoric acid. e IR spectrum of the
compound 5d showed absorption peak at 1623cm−1 due
Results and discussion
1
Chemistry
to the C=N stretching vibrations. In the H NMR spectra
e key intermediate N1(diphenylethanoyl)-N4-aryl thi-
osemicarbazides (2a–e) were synthesised by refluxing a
mixture of diphenyl acetic acid hydrazide and the substi-
tuted phenyl isothiocyanate in ethanol. e structure of
thiosemicarbazide 2d was confirmed by its IR spectrum
which displayed IR peaks at 3274cm−1 for NH, 1654cm−1
for C=O and 1079cm−1 corresponding to C=S stretching
vibrations. e 1H NMR spectrum showed a multiplet at δ
6.30–7.41 for 14 aromatic protons. e CSNH and CONH
protons were observed at δ 9.87 and 10.75 respectively
confirming the formation of the semicarbazide. e mass
spectrum of the compound 2d showed a molecular ion
peak M+ at an m/z of 398 corresponding to the molecular
formula C22H20N2OS. e thiosemicarbazide (2a–e) were
oxidatively cyclised to 5-(diphenylmethyl)-2-(4-substi-
tuted phenyl) amino-1,3,4-oxadiazoles (3a–e) by elimina-
tion of H2S using iodine and potassium iodide in ethanolic
sodium hydroxide. e IR spectrum of the oxadiazole 3d
showed an absorption peak at 1612cm−1 corresponding
to C=N stretching vibrations. e structure was further
supported by its 1H NMR spectrum, which showed a mul-
tiplet at δ 7.10–7.36 for fourteen aromatic protons. e
disappearance of both CSNH and CONH singlet signals of
thiosemicarbazide and the appearance of an NH signal at
δ 8.57 confirmed the formation of an oxadiazole ring. e
mass spectrum of compound 3d showed a molecular ion
peak M+ at an m/z of 323 corresponding to the molecular
formula C22H19N3O. On heating with 4N-NaOH in ethanol
the thiosemicarbazide (2a–e) underwent smooth cyclisa-
tionthroughdehydrationtoaffordthe5-(diphenylmethyl)-
4-(4-substituted phenyl)-3-mercapto (4H)-1,2,4-triazole
(4a–e). e structure of triazole 4d was confirmed by
its IR spectrum, which displayed an absorption peak at
1623cm−1 due to C=N and at 2564cm−1 corresponding to
an SH group. e formation of the triazole ring was further
supported by its 1H NMR spectrum which showed a broad
of the compound the singlet of CSNH and CONH of the
semicarbazide disappeared. e NH proton at the second
position of the thiadiazole ring appeared as a singlet at
δ 7.91 confirming the structure. e mass spectra of the
compound showed a molecular ion peak M+ at an m/z of
357 corresponding to the molecular formula C22H19N3S.
All the compounds were synthesised in a good yield of
between 62–85.4%. TLC and elemental analysis were used
to check the purity of the compounds. Both analytical and
spectral data (IR and 1H NMR) confirmed the structure of
the compounds.
Pharmacology
Anti-inflammatory activity
e anti-inflammatory activity of the synthesised com-
pounds 3a–e, 4a–e and 5a–e were evaluated by car-
rageenan induced paw edema method of Winter et al.
e compounds were tested at an equimolar oral dose
relative to 70 mg/kg of ibuprofen. e percentage inhi-
bition was calculated after 3 and 4 h, and since it was
found to be more after 4h, this was made to be the basis
of this discussion. e tested compounds showed anti-
inflammatory activity ranging from 50.82% to 82.25%
(Table 1). Whereas the standard drug ibuprofen showed
75.12% inhibition after 4h. e anti-inflammatory activ-
ity of 1,3,4 oxadiazole derivatives 3a–e were in the range
of 50.82 to 82.25%. e oxadiazole derivative 3b having a
4-fluoro phenyl amino group showed the highest activity
(82.25%) and this was more than the standard drug ibu-
profen (75.12%). When the group was replaced by a 3Cl-
4F-phenyl amino group (3c) there was a slight decrease
in activity (81.43%). It was observed that oxadiazole
derivatives having 4Cl-phenyl amino (3a), 4-methoxy
phenyl amino (3e) and 4-methyl phenyl amino (3d)
groups at the second position showed a decreasing
Table 1. Anti-inflammatory activity of compounds (3a–e, 4a–e and 5a–e).
Anti-inflammatory activity % inhibition SEM#
Anti-inflammatory activity % inhibition SEM#
Compound
After 3h
After 4h
Compound
After 3h
After 4h
Ibuprofen
72.67 3.42
58.33 3.6
81.68 1.73
75.12 3.95
62.87 3.79a
82.25 1.55c
81.43 2.17c
50.82 4.24a
51.24 4.72a
59.85 2.73a
57.95 1.87a
4c
4d
4e
5a
5b
5c
5d
5e
58.95 4.06
53.24 4.56
64.38 4.77
52.56 2.56
58.18 3.13
62.3 3.6
70.95 3.2c
65.52 4.54c
72.58 2.99c
55.29 2.47a
63.26 3.53b
67.92 1.52c
64.95 3.93c
65.11 2.24c
3a
3b
3c
3d
3e
4a
4b
77.24
4
50.81 5.64
50.16 3.35
56.81 1.94
56.38 3.34
59.68 3.78
62.41 3.58
#Relative to standard and data were analyzed by student’s t test for n=6
ap <0.01; bp <0.05; cp <0.5
Journal of Enzyme Inhibition and Medicinal Chemistry

Design, synthesis and pharmacological evaluation of novel azole derivatives
147
Table 2. Analgesic, ulcerogenic and lipid peroxidation activities of selected compounds.
Analgesic Activity#
Pre-treatment/ normal Post-treatment /after
UlcerogenicActivity
nmol MDA content
Compound
0h (s)
4h (s)
% Inhibition
85.53 2.09b
73.8 1.24
66.14 1.9c
34.4 1.27a
68.5 1.42b
59.55 0.84a
67.46 1.67e
—
(Severityindex SEM) #
SEM / 100mg tissue#
4.27 0.59c
3.41 0.03a
5.25 0.33c
—
3b
3c
4c
4d
4e
5c
5e
1.59 0.021
1.28 0.013
1.27 0.013
1.86 0.021
1.37 0.025
1.36 0.011
1.26 0.014
—
2.95 0.018
2.21 0.010
2.11 0.010
2.50 0.016
2.14 0.015
2.17 0.013
2.10 0.016
—
0.333 0.1e
0.166 0.1c
0.5 0.18
—
0.333 0.1e
4.21 0.17a
—
—
0.333 0.1e
0
5.19 0.26b
3.25 0.05
6.55 0.03
Control
Ibuprofen
1.36 0.009
2.37 0.012
74.26 1.25
0.5 0
#Relative to standard and data where analysed by student t test for n=6
ap <0.0001; bp <0.001; cp <0.01; dp <0.05; ep <0.5
order of anti-inflammatory activity of 62.87%, 51.24%
and 50.81% respectively.
index of 0.5 0. e maximum reduction in ulcerogenic
activity (0.166 0.105) was found for compound (3c) hav-
ing a 3Cl-4F-phenylamino group at the second position
of the oxadiazole ring. Rest of the compound also showed
an improved GI safety profile compared to ibuprofen, as
illustrated in Table 2. us the results showed that sub-
stitution of the carboxylic group by a 1,3,4-oxadiazole/
thiadiazole and 1,2,4-triazole, has resulted in significant
anti-inflammatory and analgesic activities along with
reduced ulcerogenic potential. As the anti-inflammatory,
analgesic and ulcerogenic activity were performed only
on a single dose, the dose related or graded pharmaco-
logical activity has not been explored.
e anti-inflammatory activity of the 1,2,4-triazole
derivatives 4a–e were found to be between 59.75%
and 72.58%. e maximum activity was found in the
triazole derivatives 4e, having a 4-methoxy phenyl
group at position 4. When this group was replaced by
a 3Cl, 4F-phenyl group (4c), the activity was slightly
decreased. e triazole derivatives showed moderate to
weak anti-inflammatory activity for this test. e 1,3,4-
thiadiazole derivatives 5a–e showed anti-inflammatory
activity between 55.29% to 67.92%. It was observed that
thiadiazole derivatives having 4F-phenyl amino (5b),
3Cl,4F-phenyl amino (5c), 4-methyl phenyl amino (5d)
and 4-methoxy phenyl amino (5e) group showed good
activity of 63.26%, 67.92%, 64.95% and 65.11% respec-
tively. Compound 5a having a 4-chloro phenyl amino
group showed weak anti-inflammatory activity. e
compounds 3b–e, 4c–e, 5b and 5e showed 65% anti-
inflammatory activity, and were further tested for their
analgesic activity at an equimolar oral dose relative to
70 mg/kg ibuprofen (Table 2). e compounds showed
analgesic activity ranging from 34.4% to 85.53% whereas
the standard drug ibuprofen showed 74.26% inhibition.
It was found that compound 3b, an oxadiazole deriva-
tive having the highest anti-inflammatory activity, also
showed the highest analgesic activity (85.53%). e com-
pound (3c) having a 3Cl-4F-phenyl amino group also
showed significant analgesic activity (73.5%). e other
oxadiazole, triazole and thiadiazole derivatives showed
moderate to good analgesic activity except compound
(4d), a triazole derivative which showed minimum anal-
gesic activity (34.4%).
Lipid peroxidation
It has been reported that compounds with a lower
ulcerogenic activity also had a reduced malondialde-
hyde (MDA) content, a by product of lipid peroxidation
[24]. erefore, an attempt was made to correlate the
decrease in ulcerogenic activity of the compounds with
that of lipid peroxidation. All the compounds screened
for ulcerogenic activity were also analysed for their effect
on lipid peroxidation. e lipid peroxidation was mea-
sured as nanomoles of malondialdehyde (MDA)/100 mg
of gastric mucosa tissue. Ibuprofen exhibited maximum
tissue lipid peroxidation 6.55 0.026, whereas the control
group showed a level of 3.25 0.05. It was found that all
the cyclise derivatives showing less ulcerogenic activity
also showed reduction in lipid peroxidation (range of
3.41–5.25, Table 2). us these studies showed that the
synthesised compounds have inhibited the induction of
gastric mucosal lesions and the results further suggested
that their protective effect might be related to the inhibi-
tion of lipid peroxidation in the gastric mucosa.
Acute ulcerogenic activity
e compounds 3b, 3c, 4c, 4e and 5e showing high
analgesic activity were further screened for their acute
ulcerogenic activity. e compounds were tested at an
equimolar oral dose relative to 210mg/kg ibuprofen.
e tested compound showed a significant reduction in
ulcerogenic activity ranging from 0.5 0 to 0.166 0.105
whereas the standard drug, ibuprofen showed a severity
Conclusion
Various derivatives of diphenyl acetic acid containing
1,3,4-oxadiazole/thiadiazole and 1,2,4-triazole nucleus
were successfully synthesised and screened for anti-
inflammatory, analgesic, ulcerogenic activities and lipid
peroxidation studies. Several of these compounds have
© 2011 Informa UK, Ltd.

148
Mohammed Amir et al.
9. Dogne JM, Supuran CT, Pratico D. Adverse Cardiovascular Effects
of the Coxibs. J Med Chem 2005;48:2251–2257.
10. Kalgutkar AS, Marnett AB, Crews BC, Remmel RP. Ester and
amide derivatives of the nonsteroidal antiinflammatory drug,
indomethacin, as selective cyclooxygenase-2 inhibitors. J Med
Chem 2000;43:2860–2870.
11. Galanakis D, Kourounakis AP, Tsiakitzis KC, Doulgkeris C, Rekka
EA, Gavala, A, Kravaritou C, Charitos C, Kourounakis PN. Synthesis
and pharmacological evaluation of amide conjugates of NSAIDs
withL-cysteineethylester,combiningpotentantiinflammatoryand
antioxidant properties with significantly reduced gastrointestinal
toxicity. Bioorg Med Chem Lett 2004;14:3639–3643.
12. Kucukguzel SG, Kucukguzel I, Tatar E, Rollas S, Sahin F, Gulluce
M, Clercq ED, Kabasakal L. Synthesis of some novel heterocyclic
compounds derived from diflunisal hydrazide as potential
anti-infective and anti-inflammatory agents. Eur J Med Chem
2007;42:893–901.
13. Metwally KA, Yasheen SH, Lashine ESM, Fayomi HME, Sadek
MME. Non-carboxylic analogues of arylpropionic acids: Synthesis,
anti-inflammatory activity and ulcerogenic potential. Eur J Med
Chem 2007;42:152–160.
14. Amir M, Javed SA, Kumar H. Synthesis of some 1,3,4-oxadiazole
derivatives as potential anti-inflammatory agents. Ind J Chem
2007;46B:1014–1019.
15. Schenone S, Brullo C, Bruno O, Bondavalli F, Ranise A, Filippeli W,
Rinaldi B, Capuano A, Falcone G. New 1,3,4-thiadiazole derivatives
endowed with analgesic and anti-inflammatory activities. Bioorg
Med Chem 2006;14:1698–1705.
16. Tozkoparan B, Kupeli E, Yesilada E, Ertan M. Preparation of
5-aryl-3-alkylthio-l,2,4-triazoles and corresponding sulfones
with antiinflammatory–analgesic activity. Bioorg Med Chem
2007;15:1808–1814.
been evaluated as potential anti-inflammatory-analgesic
agents with minimum ulcerogenic potential and lipid
peroxidation. e tested compounds were found to be
less irritating to the gastric mucosa as indicated by the
severity index. e lipid peroxidation values of the com-
pounds tested were also reduced. Among the synthesised
compounds, 3b and 3c possessed the most prominent
and consistent activity with the maximum reduction in
gastrointestinal toxicity and minimum lipid peroxida-
tion. Further studies to acquire more information about
the structure-activity relationships are in progress in our
laboratories.
Acknowledgements
eauthorswouldliketothanktheCentralDrugResearch
Institute (CDRI) and the Central Instrumentation Facility
(CIF), Hamdard University for the spectral analysis of
the compounds. e authors would also like to thank
Shaukat Shah, (in-charge of the animal house) and Jamia
Hamdard for providing the Wistar rats.
Declaration of interest
e authors report no conflicts of interest. e authors
alone are responsible for the content and writing of the
paper.
17. Amir M, Kumar H, Javed SA. Synthesis and pharmacological
evaluation of condensed heterocyclic 6-substituted-1,2,4-
triazolo[3,4-b]-1,3,4-thiadiazole derivatives of naproxen. Bioorg
Med Chem Lett 2007;17:4504–4508.
References
18. Amir M, Kumar H, Khan SA. Synthesis and pharmacological
evaluation of pyrazoline derivatives as new anti-inflammatory and
analgesic agents. Bioorg Med Chem Lett 2008;18:918–922.
19. Amir M, Kumar H, Javed SA. Condensed bridgehead nitrogen
heterocyclic system: Synthesis and pharmacological activities of
1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazolederivativesofibuprofenand
biphenyl-4-yloxy acetic acid. Eur J Med Chem 2008;43:2056–2066.
20. Winter CA, Risley EA, Nuss GW. Carrageenin-induced edema in
hind paw of the rat as an assay for anti-inflammatory drugs. Proc
Soc Exp Biol Med 1962;111:544–547.
1. Wolfe MM, Lichetenstein DR, Singh G. Gastrointestinal toxicity
of nonsteroidal antiinflammatory drugs. New Eng
1999;340:1888–1899.
J Med
2. Dannhardt G, Kiefer W. Cyclooxygenase inhibitors – current status
and future prospects. Eur J Med Chem 2001;36:109–126.
3. Carter JS. Inhibitors of cyclooxygenase-2. Expert Opin er Pathol
2000;10:1011–1022.
4. Talley JJ. Selective inhibitors of cyclooxygenase-2 (COX -2). Prog
Med Chem 1999;36:201–234.
21. Adeyemi OO, Okpo OS, Okpaka O. e analgesic effect of the
methanolic extract of acanthus montanus. J Ethnopharmacol
2004;90:45–48.
22. Cioli V, Putzolu S, Rossi V, Barcellona SP, Corradino C. e role of
direct tissue contact in the production of gastrointestinal ulcers
by anti-inflammatory drugs in rats. Toxicol Appl Pharmacol
1979;50:283–289.
5. Marnett L, Kalgutkar AS. A: Cyclooxygenase 2 inhibitors: Discovery,
selectivity and the future. Trend Pharmacol Sci 1999;20:465–469.
6. Almansa C, Alfon J, De Arriba A, Cavalcanti F, Escamilla I, Gomez
L, Miralles A, Soliva R, Bartolli J, Carceller E, Merlos M, Garcia-
Rafanell J. Synthesis and structure-activity relationship of a new
series of COX-2 selective inhibitors: 1,5- diarylimidazoles. J Med
Chem 2003;46:3463–3475.
23. Ohkawa H, Ohishi M, Yagi K. Assay for lipid peroxides in
animal tissues by thiobarbituric acid reaction. Anal Biochem
1979;95:351–358.
7. Kalgutkar AS. Selective cyclooxygenase-2 inhibitors as non-
ulcerogenic anti- inflammatory agents. Exp Opin Invest Drugs
1999;9:831–849.
24. Phole T, Brzozowski T, Becker JC, Vander Voort IR, Markman A,
Konturek SJ, Moniczewski A, Domschke W, Konturek JW. Role of
reactive oxygen metabolites in aspirin-induced gastric damage in
humans: gastroprotection by vitamin C. Aliment Pharmacol er
2001;15:677–687.
8. Tally JJ, Bertenshaw RS, Brown DL, Carter JS, Graneto MJ, Kellogg
MS, Kobolt CM, Yuan J Zhang YY, Seibert K. N-[[(5-Methyl-3-
phenylisoxazol-4-yl)- phenyl]sulfonyl]propanamide, sodium salt,
parecoxib sodium: A potent and selective inhibitor of COX-2 for
parenteral administration. J Med Chem 2000; 43:1661–1663.
Journal of Enzyme Inhibition and Medicinal Chemistry