Synthesis and pharmacological evaluation of some novel 2-(5-hydroxy-5- trifluoromethyl-4,5-dihydropyrazol-1-yl)-4-(coumarin-3-yl)thiazoles

Article abstract of DOI:10.1016/j.ejmech.2012.11.046

A series of novel 2-(5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-yl)- 4-(coumarin-3-yl)thiazoles (6) were synthesized by condensing 3-(2-bromoacetyl)coumarins (4) with various 5-hydroxy-5-trifluoromethyl-4,5- dihydropyrazol-1-thiocarboxamides (5), obtained by the reaction of thiosemicarbazide with trifluoromethyl-β-diketones. All the tested compounds displayed significant to moderate in vivo anti-inflammatory activity when compared to the standard drug indomethacin, and good broad spectrum in vitro antibacterial activity against three Gram-positive and four Gram-negative bacteria when compared with cefixime.

Full text of DOI:10.1016/j.ejmech.2012.11.046

European Journal of Medicinal Chemistry 62 (2013) 508e514
Contents lists available at SciVerse ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and pharmacological evaluation of some novel 2-(5-hydroxy-
5-trifluoromethyl-4,5-dihydropyrazol-1-yl)-4-(coumarin-3-yl)
thiazoles
,
a
b
b
c
Ranjana Aggarwal a , Sunil Kumar , Pawan Kaushik , Dhirender Kaushik , Girish Kumar Gupta
*
a Department of Chemistry, Kurukshetra University, Kurukshetra 136119, India
b Department of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 136119, India
c M. M. College of Pharmacy, M. M. University, Mullana, Ambala 133203, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of novel 2-(5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-yl)-4-(coumarin-3-yl)thiazoles (6)
weresynthesized bycondensing3-(2-bromoacetyl)coumarins(4)withvarious5-hydroxy-5-trifluoromethyl-
4,5-dihydropyrazol-1-thiocarboxamides (5), obtained by the reaction of thiosemicarbazide with tri-
Received 27 April 2012
Received in revised form
3 November 2012
Accepted 8 November 2012
Available online 26 January 2013
fluoromethyl-b-diketones. All the tested compounds displayed significant to moderate in vivo anti-
inflammatory activity when compared to the standard drug indomethacin, and good broad spectrum
in vitro antibacterial activity against three Gram-positive and four Gram-negative bacteria when compared
with cefixime.
Keywords:
Ó 2013 Elsevier Masson SAS. All rights reserved.
3-(2-Bromoacetyl)coumarins
2-(5-Hydroxy-5-trifluoromethyl-4,5-
dihydropyrazol-1-yl)-4-(coumarin-3-yl)
thiazoles
Anti-inflammatory activity
Antibacterial activity
1. Introduction
bacteria especially towards strain of Staphylococcus aureus [9,10].
Warfarin, a naturally occurring coumarin derivative and dicou-
Thiazole moiety is a prevalent scaffold in a number of naturally
occurring and synthetic molecules with attractive biological ac-
tivities such as antiviral, anticancer, antibacterial, antifungal, anti-
convulsant, antiparkinsonian and anti-inflammatory activities that
is well illustrated by the large number of drugs in the market
containing this heterocyclic moiety [1e8]. The presence of pyrazole
and pyrazoline nuclei is a common feature in the chemical struc-
ture of several COX-2 inhibitors. The most common COX-2 selective
inhibitors-celecoxib and SC-558 contain a pyrazole moiety. Many
pyrazolines like kebuzone, mefobutazone, ramifenazone and phe-
nylbutazone etc. are already reported in literature having potent
anti-inflammatory activity. Similarly, antibiotics containing cou-
marin ring exhibit antibacterial activity against Gram-positive
marol, a synthetic analogue, are used as anticoagulant to prevent
clotting of blood in veins, lungs and heart [11,12]. Phenprocoumon
shows high activity against the protease enzyme HIV-PR with an
inhibition potential of 1 mM [13].
Recently, synthesis of many substituted coumarin derivatives
having heterocyclic ring e.g. thiazole, pyrazole/pyrazoline moiety (ie
iii, Fig. 1) has been reported in the literature to possess antimicrobial,
analgesic and anti-inflammatory activities [14e16]. Maddi et al. have
described the synthesis of 5-aryl-3-(3-coumarinyl)-1-phenyl-2-
pyrazolines (iv, Fig. 1), as anti-inflammatory agents [17]. Therefore, it
was thought that the introduction of pyrazole/pyrazoline and cou-
marin moieties in thiazole derivatives may render them as useful
substances in drug research. Also, the high lipophilicity of the tri-
fluoromethyl group improves transport characteristics of the molecule
in vivo and thus allows the avoidance of undesirable metabolic trans-
formations [18,19]. In view of these observations and in continuation of
our research program on the synthesis of fluorinated heterocyclic
compounds [20e25], we herein report the syntheses of some novel
2,4-disubstituted thiazoles containing 5-trifluoromethylpyrazoline
and coumarin rings at positions 2 and 4, respectively, which have
* Corresponding author. Tel.: þ91 (1744)238734, þ91 9896740740; fax: þ91
(1744)238277.
E-mail addresses: ranjanaaggarwal67@gmail.com, ranjana67in@yahoo.com
(R. Aggarwal).
0223-5234/$ e see front matter Ó 2013 Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.ejmech.2012.11.046

R. Aggarwal et al. / European Journal of Medicinal Chemistry 62 (2013) 508e514
509
O
O
N
S
N
NH
HN
N
Ar
S
N
N
N
O
O
H
(i)
(ii)
O
O
O
NH
Br
N N
N
H
N
Ar
S
H
H
H
O
Cl
O
(iii)
(iv)
Fig. 1. Some bioactive coumarin containing heterocycles.
been found to possess an interesting profile of anti-inflammatory and
antibacterial activities.
the presence of pyrazoline ring by exhibiting signals at about
d
44
and 93 ppm as a quartet (2JCeF ¼ 30e35 Hz) attached to sp3 car-
bons due to C4 and C5 carbons, respectively. Finally, 19F NMR
spectra of 6 showed a signal in the range
which is characteristic for CF3 bound to saturated carbon. In case
of 6aec, second CF3 resonated at
a typical position of CF3 located at position-3 of hydroxypyrazo-
line. These values are in accordance with the literature value [20e
22,27e29].
d
ꢀ81 to ꢀ80 ppm,
2. Results and discussion
d
ꢀ67 to ꢀ66 ppm, which is
2.1. Chemistry
3-Acetylcoumarins (3), obtained by the reaction of salicylalde-
hydes (1) with ethyl acetoacetate (2) in presence of catalytic
amount of piperidine, were brominated in chloroform to obtain
corresponding 3-(2-bromoacetyl)coumarins (4) [26]. Synthesis of
the other precursors 5-hydroxy-5-trifluoromethylpyrazol-1-
thiocarboxamides (5) was accomplished by the condensation of
2.2. Biological evaluation
2.2.1. In vivo anti-inflammatory activity
various trifluoromethyl-
cording to literature procedure [20]. The synthetic reactions are
outlined in Scheme 1.
Synthesis of the title compounds 2-(5-hydroxy-5-trifluoromethyl-
4,5-dihydropyrazol-1-yl)-4-(coumarin-3-yl)thiazoles (6) was accom-
plished following the well known Hantzsch’s thiazole synthesis
involving the reaction of synthons 5 and 4. Thiazole formation in
ethanol was indicated by the appearance of yellow colour of the re-
action mixture and was found to be completed in 6 h (observed
by TLC).
b
-diketones with thiosemicarbazide ac-
Six synthesized compounds 6a, 6b, 6d, 6e, 6g and 6j were
evaluated for their in vivo anti-inflammatory activity using
carrageenan-induced paw oedema method described by Winter
et al. [30]. The protocol of animal experiments has been approved
by the Institutional Animal Ethics Committee (IAEC). Each test
compound was dosed orally (50 mg/kg body weight) 30 min prior
to induction of inflammation by carrageenan injection. Indome-
thacin was utilized as a reference anti-inflammatory drug at a dose
of 10 mg/kg, i.p. The results of anti-inflammatory activity of the
tested compounds and the reference non-steroidal anti-inflam-
matory drug indomethacin are listed in Table 1.
Recently, we have reported the synthesis of some fluorinated
pyrazolylthiazoles in which the synthesis of thiazole ring is accom-
panied by simultaneous dehydration of 4-phenyl-2-(3-phenyl-5-
hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-yl)thiazole to 4-
phenyl-2-(3-phenyl-5-trifluoromethylpyrazol-1-yl)thiazole under
the reaction conditions [20]. However, in the present work presence
of a strong electron withdrawing coumarin ring in 6 makes them
resistant to undergo dehydration under neutral conditions. Structure
of all the newly synthesized compounds was established by spectral
data such as IR, mass, NMR (1H, 13C and 19F) and elemental analyses.
These data are given in the Experimental part. The complete
assignment of carbon signals of the compounds 6 and NMR spectra
are given in Supplementary information.
All the tested compounds exhibited potent anti-inflammatory
activity (73e86% reduction in inflammation after
1 h), sig-
nificantly p < 0.01. Activity table shows that the synthesized
compounds act as fast acting anti-inflammatory agents and also
remain active for a long duration of 4 h. Compounds 6a (R1 ¼ CF3,
R ¼ H) and 6b (R1 ¼ CF3, R ¼ Cl) showed the highest (83 and 86%,
respectively) anti-inflammatory activity, when compared to stan-
dard anti-inflammatory drug indomethacin (94%).
There are in fact a large number of enzymes/receptors involved
in inflammatory process. Without specific tests it is quite difficult to
hypothesize the mechanism of action of active compounds. Prob-
ably, the active compounds exert their action via inhibition of the
cyclooxygenase enzymes like other non-steroidal anti-inflamma-
tory agents. Carrageenan-induced inflammation is a non-specific
inflammation resulting from a complex of diverse mediators [31].
This model is conventional, sensitive and accepted for screening of
newer anti-inflammatory agents [32]. Further, this model reliably
predicts the anti-inflammatory efficacy based on the inhibition of
prostaglandin amplification [33].
The 1H NMR spectra of 6 displayed two doublets appearing
at about
21 Hz) (about
d
3.85 (JHAeHB ¼ 18e21 Hz) and
d
3.70 ppm (JHAeHB ¼ 18e
d
3.73 and 3.55 ppm for 6aec) due to geminal
coupling of HB with HA at position-4 of hydroxypyrazoline in 6.
Also, two singlets of one proton intensity each appearing at about
d
8.10 and
d 8.35 ppm correspond to thiazole-5H and coumarin-
4H, respectively. Further, the 13C NMR spectra of 6 confirmed

510
R. Aggarwal et al. / European Journal of Medicinal Chemistry 62 (2013) 508e514
O
O
R
H
(ii)
CH3
R
OH
O
O
1
3
(iii)
S
O
O
O
O
O
(iv)
N
H2N
N
+
R1
N
S
N
HO
R
R
Br
R1
N
HA
HB
F3C
HB
HA
4a-c
CF3
HO
5
a
-
d
6a-l
(i)
O
R
O
S
H
+
H2N N
C
NH2
R1
CF3
2
Cl
-CF3
Br
F
R1
2, 5
R1
H
Cl Br
a
b
c
1, 3, 4
a
c
b
d
Comp.
6a
R1
R
Comp.
6e
R
Comp.
6i
R1
R
CF3
CF3
CF3
H
4-Cl-C6H4
4-Cl-C6H4
4-Br-C6H4
4-Br-C6H4
Cl
Br
H
4-Br-C6H4
4-F-C6H4
4-F-C6H4
4-F-C6H4
Br
H
6b
Cl
Br
H
6f
6k
6c
6g
6k
Cl
Br
6d
4-Cl-C6H4
6h
Cl
6l
Reagents and reaction conditions: (i) ethanol, reflux; (ii) ethyl acetoacetate, piperidine, 0-5 oC, (iii) liquid Br2,
chloroform; (iv) ethanol, reflux.
Scheme 1. Synthesis of 2-(5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-yl)-4-(coumarin-3-yl)thiazoles (6ael).
2.2.2. In vitro antibacterial activity
The results were recorded for each tested compound as the average
diameter of inhibition zones of bacterial growth surrounding the
well (in millimetres) (Table 2). The Minimum Inhibitory Concen-
tration (MIC) measurements were performed using a macro-
dilution tube method [34,35] (Table 3).
Nine newly synthesized compounds were evaluated for their
in vitro antibacterial activity against pathogenic S. aureus, Bacillus
subtilis, Staphylococcus epidermidis representing Gram-positive
bacteria and Klebsiella aerogenes, Escherichia coli, Proteus mirabilis
and Pseudomonas aeruginosa representing Gram-negative bacteria
by agar well diffusion method using cefixime as the reference drug.
Results revealed that in general, all the tested compounds
possessed moderate to good antibacterial activity against Gram-
Table 1
Anti-inflammatory activity of test compounds (carrageenan-induced paw oedema test in rats).
S. No.
Compound
Mean value of oedema volumea (% inhibition)b
1 h
2 h
3 h
0.48 ꢁ 0.15** (64.81)
4 h
0.78 ꢁ 0.18** (37.90)
1.
2.
3.
4.
5.
6.
7.
6a
6b
6d
6e
6g
6j
0.12 ꢁ 0.07** (83.10)
0.10 ꢁ 0.01** (85.91)
0.16 ꢁ 0.05** (77.46)
0.19 ꢁ 0.03** (73.24)
0.17 ꢁ 0.04** (76.06)
0.18 ꢁ 0.03** (74.65)
0.04 ꢁ 0.02** (94.37)
0.71 ꢁ 0.10
0.25 ꢁ 0.09** (79.17)
0.44 ꢁ 0.07** (63.33)
0.21 ꢁ 0.07** (82.50)
0.45 ꢁ 0.01** (62.5)
0.35 ꢁ 0.08** (70.83)
0.52 ꢁ 0.05** (56.67)
0.19 ꢁ 0.04** (84.17)
1.2 ꢁ 0.23
0.62 ꢁ 0.13** (54.54)
0.71 ꢁ 0.06** (47.95)
0.79 ꢁ 0.21* (42.08)
0.88 ꢁ 0.09 (35.48)
1.06 ꢁ 0.4 (22.29)
0.26 ꢁ 0.02** (80.94)
1.364 ꢁ 0.22
0.74 ꢁ 0.12** (41.08)
0.56 ꢁ 0.20** (55.41)
0.86 ꢁ 0.10** (31.52)
0.94 ꢁ 0.16** (25.16)
1.03 ꢁ 0.08** (17.99)
0.17 ꢁ 0.03** (86.46)
1.256 ꢁ 0.09
Indomethacin
Control (DMSO)
Significantly different compared to respective control values, **p < 0.01, *p < 0.05.
a
All values are expressed as mean ꢁ SEM of five rats in each group analysed by Anova followed by Dunnett’s ‘t’ test.
b
Values in parenthesis represents % inhibition.

R. Aggarwal et al. / European Journal of Medicinal Chemistry 62 (2013) 508e514
511
Table 2
Antibacterial activity of synthesized compounds using agar well diffusion method.
S. No.
Compounda
Diameter of growth of inhibition zone (mm)b
S. aureus
B. subtilis
S. epidermidis
K. aerogenes
E. coli
P. mirabilis
P. aeruginosa
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
6c
6d
6e
6f
6h
6i
6j
6k
3.13
4.50
4.13
2.00
2.07
2.03
3.96
4.93
1.87
3.90
25.00
15.74
e
20.10
15.07
11.23
12.50
11.23
13.10
14.00
14.00
14.00
22.00
10.97
10.10
e
11.93
13.10
e
17.23
15.17
e
9.13
8.10
e
10.30
e
13.00
e
e
15.06
e
8.10
e
e
e
10.47
12.07
e
10.03
13.03
e
e
e
12.00
e
17.03
e
7.87
e
6l
12.39
26.00
10.96
15.00
10.96
14.10
e
e
Cefixime
20.00
10.00
e No activity.
a
Concentration 2.0 mg/ml.
Values, including diameter of the well (8 mm), are means of three replicates.
b
positive bacteria (S. aureus, B. subtilis, S. epidermidis) as well as
Gram-negative bacteria (K. aerogenes, E. coli, P. mirabilis and
P. aeruginosa). On the basis of zone of inhibition against the test
bacterium, compound 6c was found to be most effective against
B. subtilis, S. epidermidis; compounds 6d, 6e, 6j and 6k were
found to be most effective against S. aureus (Gram-positive bac-
teria) and compounds 6c, 6d and 6j were found to be most active
against E. coli and P. aeruginosa (Gram-negative bacteria), as
compared with the standard drug cefixime. The zone of inhibi-
tion of compounds 6d, 6e, 6j and 6k against S. aureus was
4.50 mm, 4.13 mm, 3.96 mm and 4.93 mm, respectively and the
zone of inhibition of standard antibiotic cefixime was 3.90 mm.
However, in terms of MIC compounds 6d and 6j were found to be
most effective against E. coli and P. mirabilis showing a MIC of 2
4. Experimental section
4.1. General
Melting points were determined in open capillaries in electrical
apparatus and are uncorrected. IR spectra were recorded on a Buck
Scientific IR M500 instrument. The 1H and 13C NMR spectra were
recorded on a Bruker instrument at 300 MHz and 75 MHz,
respectively. D2O exchange was applied to confirm the assignment
of the signals of OH protons. 19F NMR spectra were run on DRX 300
and DPX 400 at 282 and 376 MHz, respectively, (at SAIF, CDRI,
Lucknow, India) using trichlorofluoromethane as a standard, set-
ting the CFCl3 signal at d 0.0 ppm. Mass spectra were measured in EI
mode on a Kratos MS-50 spectrometer at MS Facilities at SAIF,
Panjab University, Chandigarh, India. Elemental analyses were
performed at NIPER (Mohali), Chandigarh, India. All the compounds
gave C, H and N analysis within ꢁ0.5 of the theoretical values.
1,1,1,6,6,6-Hexafluoroacetylacetone 2awas commerciallyavailable
and other fluorinated diketones2bed were prepared according tothe
literature procedure [36,37]. 5-Hydroxy-5-trifluoromethyl-4,5-
dihydropyrazol-1-thiocarboxamides 5aed and 3-(2-bromoacetyl)
coumarins 4aec were also synthesized according to literature pro-
cedure [20,25,26].
and 4 mg/ml, respectively, when compared to the standard anti-
biotic cefixime.
3. Conclusions
In conclusion, we have described an efficient and simple
protocol for the preparation of triheterocyclic compounds 2-(5-
hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-yl)-4-(coumarin-
3-yl)thiazoles 6 by the condensation of 5-hydroxy-5-trifluoromethyl-
4,5-dihydropyrazol-1-thiocarboxamides 5 and 3-(2-bromoacetyl)
coumarins 4 in excellent yields. The newly synthesized compounds 6
displayed significant anti-inflammatory and antibacterial activities
when compared to well known reference drugs (indomethacin and
cefixime). The preliminary studies of these compounds evidenced
that coumarin ring and trifluoromethyl group at position-3 and 5 of
pyrazoline ring enhance the antibacterial as well as anti-
inflammatory activities of thiazoles, which might serve as new tem-
plates in the synthesis and development of potent therapeutics.
4.2. General procedure for the preparation of 2-(3-alkyl/aryl-5-
hydroxy-5-trifluoromethyl-4,5-dihydropyrazo-1-yl)-4-(coumarin-
3-yl)thiazoles 6ael
An ethanolic solution (30 ml) of 3-(2-bromoacetyl)coumarin (4)
(2 mmol) and 5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-
thiocarboxamide (5) (2 mmol) was refluxed on a water bath for
6 h. On completion of the reaction (observed by TLC), solvent was
Table 3
Minimum inhibitory concentration (MIC) determination using agar well diffusion method.
S. No.
Compound
Minimum inhibitory concentration (MIC) (mg/ml)
S. aureus
B. subtilis
S. epidermidis
K. aerogenes
E. coli
P. mirabilis
P. aeruginosa
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
6c
6d
6e
6f
6h
6i
6j
6k
64
16
64
128
64
128
32
32
128
2
8
512
e
16
64
512
8
128
2
16
4
128
32
e
512
512
512
512
64
64
64
2
e
e
e
16
e
e
4
e
e
2
512
e
8
e
e
128
e
e
e
512
8
256
2
e
512
e
32
e
e
e
6l
512
2
256
2
512
2
e
Cefixime
2

512
R. Aggarwal et al. / European Journal of Medicinal Chemistry 62 (2013) 508e514
evaporated. The solid thus obtained was dissolved in chloroform
(25 ml) and neutralized with saturated solution of sodium bicar-
bonate (50 ml). Organic layer was extracted and excess solvent was
distilled off. It was recrystallized from aqueous ethanol to afford the
target compounds 6.
5-H), 7.51 (dd, 1H, J ¼ 8.7 Hz, 2.4 Hz, coumarin 7-H), 7.46 (d, 2H,
J ¼ 8.7 Hz, p-chlorophenyl 3,5-H), 7.34 (d, 1H, J ¼ 8.7 Hz, coumarin
8-H), 6.85 (bs, 1H, OH, exchangeable with D2O), 3.86 (d, 1H,
J ¼ 18.2 Hz, pyrazoline 4-HA), 3.71 (d, 1H, J ¼ 18.9 Hz, pyrazoline 4-
HB); 19F NMR (CDCl3,
d
ppm): ꢀ80.40 (5-CF3); MS (m/z): 527, 526
([M þ H]þ), 525, 393, 355, 281; Anal. Calcd. for C22H12Cl2F3N3O3S: C,
4.3. Characterization data of synthesized compounds
50.20; H, 2.30; N, 7.98. Found: C, 49.87; H, 2.28; N, 7.95.
4.3.1. 2-(5-Hydroxy-3,5-bis-trifluoromethyl-4,5-dihydropyrazol-1-
yl)-4-(coumarin-3-yl)thiazole (6a)
4.3.6. 2-(3-(4-Chlorophenyl)-5-hydroxy-5-trifluoromethyl-4,5-dih-
ydropyrazol-1-yl)-4-(6-bromo-coumarin-3-yl)thiazole (6f)
Yield 87%; mp 253e254 ꢂC; IR (KBr, cmꢀ1): 2957 (OH), 1720 (C]
Yield 86%; mp 230e232 ꢂC; IR (KBr, cmꢀ1): 2974 (OH), 1720 (C]
O), 1535, 1273, 1180, 1142, 1095, 756; 1H NMR (300 MHz, CDCl3,
O),1543,1304,1173,1095,1003, 825, 787; 1H NMR (300 MHz, CDCl3,
d
ppm): 8.34 (s,1H, coumarin 4-H), 8.13 (s,1H, thiazole 5-H), 7.67 (d,
d ppm): 8.29 (s, 1H, coumarin 4-H), 8.08 (s, 1H, thiazole 5-H), 7.81
1H, J ¼ 7.5 Hz, coumarin 5-H), 7.61e7.41 (m, 3H, coumarin 6,7,8-H),
6.86 (bs, 1H, OH, exchangeable with D2O), 3.73 (d, 1H, J ¼ 19.5 Hz,
pyrazoline 4-HA), 3.55 (d, 1H, J ¼ 20.1 Hz, pyrazoline 4-HB); 19F NMR
(d, 1H, J ¼ 2.1 Hz, coumarin 5-H), 7.70 (d, 2H, J ¼ 8.4 Hz, p-chlor-
ophenyl 3,5-H), 7.65 (dd, 1H, J ¼ 8.7 Hz, 2.1 Hz, coumarin 7-H), 7.46
(d, 2H, J ¼ 8.4 Hz, p-chlorophenyl 2,6-H), 7.28 (d, 1H, J ¼ 6.9 Hz,
coumarin 8-H), 6.84 (bs, 1H, OH, exchangeable with D2O), 3.86 (d,
1H, J ¼ 18.6 Hz, pyrazoline 4-HA), 3.71 (d, 1H, J ¼ 18.9 Hz, pyrazoline
(CDCl3,
d
ppm): ꢀ80.33 (5-CF3), ꢀ67.02 (3-CF3); MS (m/z): 452, 450
([M þ H]þ), 412, 403, 355, 267; Anal. Calcd. for C17H9F6N3O3S: C,
45.44; H, 2.02; N, 9.35. Found: C, 45.23; H, 2.10; N, 9.32.
4-HB); 19F NMR (CDCl3,
d
ppm): ꢀ80.28 (5-CF3); MS (m/z): 572, 570
([M þ H]þ), 473, 355, 299, 281; Anal. Calcd. for C22H12BrClF3N3O3S:
4.3.2. 2-(5-Hydroxy-3,5-bis-trifluoromethyl-4,5-dihydropyrazol-1-
yl)-4-(6-chloro-coumarin-3-yl)thiazole (6b)
C, 46.29; H, 2.12; N, 7.36. Found: C, 46.12; H, 2.12; N, 7.35.
Yield 91%; mp 239e40 ꢂC; IR (KBr, cmꢀ1): 2948 (OH), 1720 (C]
4.3.7. 2-(3-(4-Bromophenyl)-5-hydroxy-5-trifluoromethyl-4,5-dih-
ydropyrazol-1-yl)-4-(coumarin-3-yl)thiazole (6g)
O), 1493, 1273, 1170, 1121, 1092, 767; 1H NMR (300 MHz, CDCl3,
d
ppm): 8.26 (s,1H, coumarin 4-H), 8.14 (s,1H, thiazole 5-H), 7.65 (d,
Yield 89%; mp 232e234 ꢂC; IR (KBr, cmꢀ1): 2997 (OH), 1718 (C]
1H, J ¼ 2.4 Hz, coumarin 5-H), 7.53 (dd, 1H, J ¼ 8.7 Hz, 2.4 Hz,
coumarin 7-H), 7.35 (d, 1H, J ¼ 8.7 Hz, coumarin 8-H), 6.73 (bs, 1H,
OH, exchangeable with D2O), 3.73 (d, 1H, J ¼ 19.2 Hz, pyrazoline 4-
HA), 3.55 (d, 1H, J ¼ 19.2 Hz, pyrazoline 4-HB); 19F NMR (CDCl3,
O), 1543, 1281, 1108, 949, 769; 1H NMR (300 MHz, CDCl3,
d ppm):
8.39 (s, 1H, coumarin 4-H), 8.07 (s, 1H, thiazole 5-H), 7.67 (d, 1H,
J ¼ 7.5 Hz, coumarin 5-H), 7.62 (m, 4H, p-bromophenyl), 7.57 (d, 1H,
J ¼ 7.2 Hz, coumarin 7-H), 7.41 (m, 2H, coumarin 6,8-H), 6.99 (bs,
1H, OH, exchangeable with D2O), 3.86 (d, 1H, J ¼ 18.3 Hz, pyrazoline
4-HA), 3.72 (d, 1H, J ¼ 18.3 Hz, pyrazoline 4-HB); 19F NMR (CDCl3,
d
ppm): ꢀ80.26 (5-CF3), ꢀ66.94 (3-CF3); MS (m/z): 486, 484
([M þ H]þ), 448, 355, 281. Anal. Calcd. for C17H8ClF6N3O3S: C, 42.21;
H, 1.67; N, 8.69. Found: C, 42.20; H, 1.61; N, 8.65.
d
ppm): ꢀ80.50 (5-CF3); MS (m/z): 537 ([M þ H]þ), 535, 497, 438,
355, 281; Anal. Calcd. for C22H13BrF3N3O3S: C, 49.27; H, 2.44; N,
7.83. Found: C, 49.22; H, 2.41; N, 7.85.
4.3.3. 2-(5-Hydroxy-3,5-bis-trifluoromethyl-4,5-dihydropyrazol-1-
yl)-4-(6-bromo-coumarin-3-yl)thiazole (6c)
Yield 85%; mp 250e251ꢂC;IR (KBr, cmꢀ1):2993 (OH),1728 (C]O),
4.3.8. 2-(3-(4-Bromophenyl)-5-hydroxy-5-trifluoromethyl-4,5-dih-
ydropyrazol-1-yl)-4-(6-chloro-coumarin-3-yl)thiazole (6h)
1535, 1180, 1157, 1103, 1080, 1003, 787; 1H NMR (300 MHz, CDCl3,
d
ppm): 8.24 (s, 1H, coumarin 4-H), 8.13 (s, 1H, thiazole 5-H), 7.79 (d,
Yield 87%; mp 237e238 ꢂC; IR (KBr, cmꢀ1): 3032 (OH), 1715 (C]
1H, J ¼ 2.1 Hz, coumarin 5-H), 7.66 (dd,1H, J ¼ 8.7Hz, 2.4 Hz, coumarin
7-H), 7.28 (d, 1H, J ¼ 7.5 Hz, coumarin 8-H), 6.72 (bs, 1H, OH,
exchangeablewithD2O),3.73(d,1H, J¼ 19.2Hz,pyrazoline4-HB), 3.55
O), 1548, 1287, 1149, 1018, 818, 787; 1H NMR (300 MHz, CDCl3,
d
ppm): 8.29 (s,1H, coumarin 4-H), 8.08 (s,1H, thiazole 5-H), 7.65 (s,
1H, J ¼ 2.4 Hz, coumarin 5-H), 7.61 (m, 4H, p-bromophenyl), 7.51
(dd, 1H, J ¼ 8.7 Hz, 2.4 Hz, coumarin 7-H), 7.34 (d, 1H, J ¼ 9.0 Hz,
coumarin 8-H), 6.86 (bs, 1H, OH, exchangeable with D2O), 3.86 (d,
1H, J ¼ 18.3 Hz, pyrazoline 4-HA), 3.71 (d, 1H, J ¼ 18.3 Hz, pyrazoline
(d, 1H, J ¼ 19.5 Hz, pyrazoline 4-HB); 19F NMR (CDCl3,
ppm): ꢀ78.75
d
(5-CF3), ꢀ62.42 (3-CF3); MS (m/z): 529, 528 ([M þ H]þ), 526, 512, 492,
475, 355, 281;Anal. Calcd. for C17H8BrF6N3O3S:C 38.65;H 1.53; N 7.95.
Found: C, 38.74; H, 1.14; N, 7.80.
4-HB); 19F NMR (CDCl3,
d ppm): -80.65 (5-CF3); MS (m/z): 572, 570
([M þ H]þ), 355, 281, 299, 267; Anal. Calcd. for C22H12BrClF3N3O3S:
4.3.4. 2-(3-(4-Chlorophenyl)-5-hydroxy-5-trifluoromethyl-4,5-dih-
ydropyrazol-1-yl)-4-(coumarin-3-yl)thiazole (6d)
C, 46.29; H, 2.12; N, 7.36. Found: C, 46.22; H, 2.03; N, 7.34.
Yield87%;mp207e208ꢂC;IR(KBr, cmꢀ1):2994(OH),1720(C]O),
4.3.9. 2-(3-(4-Bromophenyl)-5-hydroxy-5-trifluoromethyl-4,5-dih-
ydropyrazol-1-yl)-4-(6-bromo-coumarin-3-yl)thiazole (6i)
1532,1284,1183,1092, 765; 1H NMR (300 MHz, CDCl3,
d ppm): 8.39 (s,
1H, coumarin 4-H), 8.07 (s,1H, thiazole 5-H), 7.71 (d, 2H, J ¼ 8.4 Hz, p-
chlorophenyl 2, 6-H), 7.65 (s, 1H, coumarin 5-H), 7.59e7.54 (m, 1H,
coumarin 7-H), 7.46 (d, 2H, J ¼ 8.4 Hz, p-chlorophenyl 3,5-H), 7.41 (m,
2H, coumarin 6,8-H), 6.99 (bs, 1H, OH, exchangeable with D2O), 3.86
(d,1H, J ¼ 18.6 Hz, pyrazoline4-HA), 3.72 (d,1H, J ¼ 18.6 Hz, pyrazoline
Yield 88%; mp 255e256 ꢂC; IR (KBr, cmꢀ1): 2952 (OH), 1720 (C]
O), 1528, 1381, 1173, 1103, 1072, 1018, 787; 1H NMR (300 MHz,
CDCl3, d ppm): 8.29 (s, 1H, coumarin 4-H), 8.07 (s, 1H, thiazole 5-H),
7.80 (d, 1H, J ¼ 2.4 Hz, coumarin 5-H), 7.65 (m, 5H, p-bromophenyl
4H and coumarin 6-H), 7.28 (d, 1H, J ¼ 8.1 Hz, coumarin 8-H), 6.84
(bs, 1H, OH, exchangeable with D2O), 3.85 (d, 1H, J ¼ 18.6 Hz, pyr-
azoline 4-HA), 3.71 (d, 1H, J ¼ 18.6 Hz, pyrazoline 4-HB); 19F NMR
4-HB); 19F NMR (CDCl3,
d
ppm): ꢀ80.12 (5-CF3); MS (m/z): 494, 492
([M þ H]þ), 355, 281, 267; Anal. Calcd. for C22H13ClF3N3O3S: C, 53.72;
H, 2.66; N, 8.54. Found: C, 53.85; H, 2.35; N, 8.76.
(CDCl3,
d
ppm): ꢀ80.32 (5-CF3); MS (m/z): 614 ([M þ H]þ), 612, 518,
355, 267; Anal. Calcd. for C22H12Br2F3N3O3S: C, 42.95; H, 1.97; N,
6.83. Found: C, 42.68; H, 1.95; N, 6.80.
4.3.5. 2-(3-(4-Chlorophenyl)-5-hydroxy-5-trifluoromethyl-4,5-dih-
ydropyrazol-1-yl)-4-(6-chloro-coumarin-3-yl)thiazole (6e)
Yield 84%; mp 222e223 ꢂC; IR (KBr, cmꢀ1): 2965 (OH), 1716 (C]
4.3.10. 2-(3-(4-Fluorophenyl)-5-hydroxy-5-trifluoromethyl-4,5-
dihydropyrazol-1-yl)-4-(coumarin-3-yl)thiazole (6j)
O), 1503, 1312, 1107, 1024, 787; 1H NMR (300 MHz, CDCl3,
d ppm):
8.29 (s, 1H, coumarin 4-H), 8.07 (s, 1H, thiazole 5-H), 7.70 (d, 2H,
J ¼ 8.4 Hz, p-chlorophenyl 2,6-H), 7.65 (d, 1H, J ¼ 2.1 Hz, coumarin
Yield 78%; mp 207e208 ꢂC; IR (KBr, cmꢀ1): 2924 (OH), 1720 (C]
O), 1605, 1535, 1311, 1180, 1095, 1018, 841, 756; 1H NMR (300 MHz,

R. Aggarwal et al. / European Journal of Medicinal Chemistry 62 (2013) 508e514
513
CDCl3, d ppm): 8.39 (s, 1H, coumarin 4-H), 8.07 (s, 1H, thiazole 5-H),
Anti ꢀ inflammatory activity ð% inhibtionÞ
¼ fðVc ꢀ Vt=VcÞg ꢃ 100
7.79 (m, 2H, p-fluorophenyl 2,6-H), 7.68 (d, 1H, J ¼ 7.2 Hz, coumarin
8-H), 7.59 (s, 1H, coumarin 5-H), 7.41 (m, 2H, coumarin 6,7-H), 7.20
(m, 2H, p-fluorophenyl 3,5-H), 7.01 (bs, 1H, OH, exchangeable with
D2O), 3.87 (d, 1H, J ¼ 18.3 Hz, pyrazoline 4-HA), 3.73 (d, 1H,
where Vt and Vc are the volume of oedema in drug treated/standard
drug and control group, respectively.
J ¼ 18.6 Hz, pyrazoline 4-HB); 19F NMR (CDCl3,
d
ppm): ꢀ80.55 (5-
CF3); MS (m/z): 476 ([M þ H]þ), 429, 357, 355, 281; Anal. Calcd. for
5.2. In vitro antibacterial assay
C
22H13F4N3O3S: C, 55.58; H, 2.76; N, 8.84. Found: C, 55.63; H, 2.41;
N, 8.40.
5.2.1. Test microorganisms
Seven pathogenic bacteria, S. aureus, B. subtilis, S. epidermidis
(Gram-positive), K. aerogenes, E. coli, P. mirabilis, and P. aeruginosa
(Gram-negative) isolated from the patients in Maharishi Markan-
deshwar Medical College, M. M. University, Mullana, Haryana, were
used in the present study.
4.3.11. 2-(3-(4-Fluorophenyl)-5-hydroxy-5-trifluoromethyl-4,5-
dihydropyrazol-1-yl)-4-(6-chloro-coumarin-3-yl))thiazole (6k)
Yield 80%; mp 241e242 ꢂC; IR (KBr, cmꢀ1): 2974 (OH), 1724 (C]
O), 1528, 1295, 1161, 1088, 958, 756; 1H NMR (300 MHz, CDCl3,
d
ppm): 8.31 (s, 1H, coumarin 4-H), 8.08 (s, 1H, thiazole 5-H), 7.78
(m, 2H, p-fluorophenyl 2,6-H), 7.66 (d, 1H, J ¼ 2.1 Hz, coumarin 5-
H), 7.52 (dd, 1H, J ¼ 2.1 Hz, 8.7 Hz, coumarin 7-H), 7.36 (m, 1H,
coumarin 8-H), 7.20 (m, 2H, p-fluorophenyl 3,5-H), 6.93 (bs,1H, OH,
exchangeable with D2O), 3.87 (d, 1H, J ¼ 18.6 Hz, pyrazoline 4-HA),
3.72 (d, 1H, J ¼ 18.6 Hz, pyrazoline 4-HB); 19F NMR (CDCl3,
5.2.2. In-vitro antibacterial activity
The antibacterial activity of nine newly synthesized compounds
was evaluated by agar well diffusion method [38]. 25 ml of nutrient
agar medium was poured into each petri plate and the agar plates
were swabbed with 100 mL inocula of each test bacterium and kept
for 15 min for adsorption. Using sterile cork borer of 8 mm diam-
eter, wells were bored into seeded agar plates and these were
d
ppm): ꢀ80.76 (5-CF3); MS (m/z): 512, 510 ([M þ H]þ), 488, 464,
390, 281; Anal. Calcd. for C22H12ClF4N3O3S: C, 51.83; H, 2.37; N,
8.24. Found: C, 51.69; H, 2.46; N, 8.40.
loaded with a 50 mL volume. Solutions of the test compounds and
standard were prepared in dimethylsulphoxide (DMSO) at con-
centration of 2.0 mg/ml. From this stock solution, two-fold di-
lutions of the compounds (2, 4, 8,.512 mg/ml) were inoculated to
4.3.12. 2-(3-(4-Fluorophenyl)-5-hydroxy-5-trifluoromethyl-4,5-
dihydropyrazol-1-yl)-4-(6-bromo-coumarin-3-yl)thiazole (6l)
Yield 75%; mp 249e251 ꢂC; IR (KBr, cmꢀ1): 2942 (OH), 1715 (C]
O), 1609, 1535, 1165, 1107, 1018, 756; 1H NMR (300 MHz, CDCl3,
the corresponding wells. All the plates were incubated at 37 ꢂC for
24 h. Antibacterial activity of compounds was evaluated by meas-
uring the zone of growth inhibition and MIC against the test or-
ganisms with zone reader (Hi Antibiotic zone scale). DMSO was
used as a negative control whereas cefixime was used as a reference
drug. Minimum Inhibitory Concentration (MIC) was determined as
the lowest concentration of the compound tested that was able to
inhibit visible growth of a microorganism after overnight incuba-
tion. The experiments were performed in triplicates and the results
averaged.
d
ppm): 8.29 (s, 1H, coumarin 4-H), 8.07 (s, 1H, thiazole 5-H), 7.80
(d, 1H, J ¼ 2.1 Hz, coumarin 5-H), 7.78 (m, 2H, p-fluorophenyl 2,6-
H), 7.64 (dd, 1H, J ¼ 2.1 Hz, 8.7 Hz, coumarin 7-H), 7.25 (m, 1H,
coumarin 8-H), 7.17 (d, 2H, J ¼ 8.7 Hz, p-fluorophenyl 3,5-H), 6.86
(bs, 1H, OH, exchangeable with D2O), 3.86 (d, 1H, J ¼ 18.6 Hz, pyr-
azoline 4-HA), 3.71 (d, 1H, J ¼ 18.9 Hz, pyrazoline 4-HB); 19F NMR
(CDCl3,
d
ppm): ꢀ80.52 (5-CF3); MS (m/z): 554 ([M þ H]þ), 552, 533,
435, 355, 267; Anal. Calcd. for C22H12BrF4N3O3S: C 47.67; H 2.18; N
7.58. Found: C, 47.53; H, 2.28; N, 7.92.
Acknowledgements
5. Pharmacological assay
We thank the Council of Scientific and Industrial Research, New
Delhi for providing the financial assistance in the form of Senior
Research Fellowship to Sunil Kumar. Thanks are also due to So-
phisticated Analytical Instrument Facility, CDRI, Lucknow; National
Institute of Pharmaceutical Education and Research, Mohali,
Chandigarh and Sophisticated Analytical Instrumentation Facility,
Panjab University, Chandigarh, India for providing 19F NMR, ele-
mental analyses and mass spectra, respectively. We also thank Dr.
S.P. Singh (Emeritus Professor, Kurukshetra University, India) for his
helpful suggestions.
5.1. In vivo anti-inflammatory assay
5.1.1. Carrageenan-induced rat paw oedema assay
Male Wistar albino rats weighing 200e250 g were used
throughout the study. They were kept in the animal house under
standard conditions of light and temperature with free access to
food and water. Food was withdrawn 12 h before and during
experimental hours. The rats were divided into three groups
(control, standard drug and drugs treated) of five animals each. One
group (control group) of five rats was kept as control and received
tween 80 (95%). Standard group received indomethacin at a dose of
10 mg/kg body weight orally. Test group received test compounds
at a dose of 50 mg/kg body weight. A mark was made on the left
hind paw just beyond the tibiotarsal articulation, so that every time
the paw was dipped up to fixed mark and constant paw volume was
ensured. A freshly prepared suspension of carrageenan (1% in 0.9%
saline), 0.1 ml was injected under the planter region of the left hind
paw of each rat. Test compounds and standard drug were admin-
istered orally to the animals, respectively 30 min before the car-
rageenan injection. The paw volume (up to the tibiotarsal
articulation) of each rat was measured at 0 h (before carrageenan
injection) and after 1 h, 2 h, 3 h and 4 h of carrageenan treatment
with the help of a Plethysmometer (model 7140, Ugo Basile, Italy).
The percentage inhibition of anti-inflammatory activity was cal-
culated according to the following equation
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2012.11.046.
References
[1] O.I. El-Sabbagh, M.M. Baraka, S.M. Ibrahim, C. Pannecouque, G. Andrei,
R. Snoeck, J. Balzarini, A.A. Rashad, Eur. J. Med. Chem. 44 (2009) 3746e3753.
[2] (i) V. Zaharia, A. Ignat, N. Palibroda, B. Ngameni, V. Kuete, C.N. Fokunang,
M.L. Moungang, B.T. Ngadjui, Eur. J. Med. Chem. 45 (2010) 5080e5085;
(ii) I. Hutchinson, S.A. Jennings, B.R. Vishnuvajjala, A.D. Westwell,
M.F.G. Stevens, J. Med. Chem. 45 (2002) 744e747.
[3] A. Kamal, M.N.A. Khan, K.S. Reddy, K. Rohini, Bioorg. Med. Chem. 15 (2007)
1004e1013.
[4] R.B. Pathak, B. Jahan, S.C. Bahel, Bokin Bobai 9 (1981) 477e480.

514
R. Aggarwal et al. / European Journal of Medicinal Chemistry 62 (2013) 508e514
ꢀ
[5] D.D. Erol, U. Calis¸ , R. Demirdamar, N. Yulug, M. Ertan, J. Pharm. Sci. 84 (1995)
462e465.
W.E. Perkins, K. Seibert, A.W. Veenhuizen, Y.Y. Zhang, P.C. Isakson, J. Med.
Chem. 40 (1997) 1347e1365.
[6] F. Azam, B.A. El-Gnidi, I.A. Alkskas, M.A. Ahmed, J. Enzym. Inhib. Med. Chem.
25 (2010) 818e826.
[20] R. Aggarwal, R. Kumar, S. Kumar, G. Garg, R. Mahajan, J. Sharma, J. Fluor. Chem.
132 (2011) 965e972.
[7] Y. Kumar, R. Green, K.Z. Boryska, D.D. Wise, L.L. Wotring, L.B. Townsend,
J. Med. Chem. 36 (1993) 3843e3848.
[8] R.N. Sharma, F.P. Xavier, K.K. Vasu, S.C. Chaturvedi, S.S. Pancholi, J. Enzym.
Inhib. Med. Chem. 24 (2009) 890e897.
[21] R. Aggarwal, R. Kumar, S.P. Singh, J. Fluor. Chem. 130 (2009) 886e893.
[22] V. Kumar, S.P. Singh, R. Aggarwal, J. Fluor. Chem. 127 (2006) 880e888.
[23] D. Sanz, R.M. Claramunt, A. Saini, V. Kumar, R. Aggarwal, S.P. Singh, I. Alkorta,
J. Elguero, Magn. Reson. Chem. 45 (2007) 513e517.
[9] D. Lafitte, V. Lamour, P. Tsvetkov, A. Makarov, M. Klich, P. Deprez, D. Moras,
C. Briand, R. Gilli, Biochemistry 41 (2002) 7217e7223.
[24] R. Aggarwal, G. Sumran, R. Kumar, S.P. Singh, Arkivoc 15 (2007) 292e302.
[25] V. Kumar, R. Aggarwal, P. Tyagi, S.P. Singh, Eur. J. Med. Chem. 40 (2005) 922e927.
[26] (i) C.F. Koelsch, -, J. Am. Chem. Soc. 72 (1950) 2993e2995;
(ii) A. Gursoy, N. Karali, Turk. J. Chem. 27 (2003) 545e552.
[27] S.P. Singh, J.K. Kapoor, D. Kumar, M.D. Threadgill, J. Fluor. Chem. 83 (1997)
73e79.
[28] S.P. Singh, D. Kumar, B.G. Jones, M.D. Threadgill, J. Fluor. Chem. 94 (1999)
199e203.
[29] L. Song, S. Zhu, J. Fluor. Chem. 111 (2001) 201e205.
[30] C.A. Winter, E.A. Risley, G.W. Nuss, Proc. Soc. Exp. Biol. Med. 111 (1962)
554e557.
[31] T.Y. Shen, Nonsteroidal antiinflammatory agents, in: M.E. Wolf (Ed.), Burger’s
Medicinal Chemistry, John Wiley and Sons, New York, 1980, pp. 1217e1219.
[32] C.A. Winter, in: S. Gattini, M.N.G. Dukes (Eds.), Nonsteroidal Antiinflammatory
Drugs, Excerpta Medica, Amsterdam, 1965, p. 190.
[33] T. Kuroda, F. Suzuki, T. Tamura, K. Ohmori, H. Hosoe, J. Med. Chem. 35 (1992)
1130e1136.
[34] J.M. Andrews, J. Antimicrob. Chemother. 48 (Suppl. 1) (2001) 5e16.
[35] NCCLS, Method for Dilution Antimicrobial Susceptibility Test for Bacteria that
Grow Aerobically; Approved Standards, fifth ed., National Committee for
Clinical Laboratory Standards, Villanova, PA, 2000.
[10] D.A. Mutlu, D.E. Dilek, Turk. J. Chem. 27 (2003) 757e764.
[11] S. Thaisrivongs, P.K. Tomich, K.D. Watenpaugh, K. Chong, W. Howe, C. Yang,
J. Strohbach, S. Tureer, J. McGrath, M. Bohanon, J. Lynn, A. Mulichak,
P. Spinelli, R. Hinshaw, P. Pagano, J. Moon, M. Ruwart, K. Wilkinson, B. Rush,
G. Zipp, R. Dalga, F. Schwende, G. Howard, G. Padbury, L. Toth, Z. Zhao,
K. Koeplinger, T. Kakuk, S. Cole, R. Zaya, R. Piper, P. Jeffrey, J. Med. Chem. 37
(1994) 3200e3204.
[12] R.G. Bell, P.T. Caldwell, Biochemistry 12 (1973) 1759e1762.
[13] S. Kirkiacharian, D. Thuy, S. Sicsic, R. Bakhchinian, R. Kurkjian, T. Tonnaire, II
Farm. 57 (2002) 703e708.
[14] A. Arshad, H. Osman, M.C. Bagley, C.K. Lam, S. Mohamad, A.S.M. Zahariluddin,
Eur. J. Med. Chem. 46 (2011) 3788e3794.
[15] A.M. Vijesh, A.M. Isloor, V. Prabhu, S. Ahmad, S. Malladi, Eur. J. Med. Chem. 45
(2010) 5460e5464.
[16] R.G. Kalkhambkar, G.M. Kulkarni, H. Shivkumar, R.N. Rao, Eur. J. Med. Chem.
42 (2007) 1272e1276.
[17] S. Khode, V. Maddi, P. Aragade, M. Palkar, P. Kumar, R.S. Mamledesai,
A.H.M. Thippeswamy, D. Satyanarayana, Eur. J. Med. Chem. 44 (2009)
1682e1688.
[18] K.L. Kees, J.J. Fitzgerald Jr., K.E. Steiner, J.F. Mattes, B. Mihan, T. Tosi,
D. Mondoro, M.L. McCalebr, J. Med. Chem. 39 (1996) 3920e3928.
[19] T.D. Penning, J.J. Talley, S.R. Bertenshaw, J.S. Carter, P.W. Collins, S. Docter,
M.J. Graneto, L.F. Lee, J.W. Malecha, J.M. Miyashiro, R.S. Rogers, D.J. Rogier,
S.S. Yu, G.D. Anderson, E.G. Burton, J.N. Cogburn, S.A. Gregory, C.M. Koboldt,
[36] M.J. Uddin, P.N. Rao, K. Praveen, E.E. Knaus, Bioorg. Med. Chem. 11 (2003)
5273e5280.
[37] K.T. Potts, J. Bhattacharya, S.L. Smith, A.M. Ihrig, C.A. Girard, J. Org. Chem. 37
(1972) 4410e4415.
[38] I. Ahmad, A.J. Beg, J. Ethnopharmacol. 74 (2001) 113e123.