Synthesis, pharmacological evaluation and docking studies of coumarin derivatives

Article abstract of DOI:10.1016/j.ejmech.2011.07.013

We synthesized coumarin derivatives using various aromatic and heterocyclic amines, and tested the target compound for its analgesic, anti-inflammatory, antimicrobial activities. Compounds 3l, 3m and 3n showed significant anti-inflammatory, analgesic and

Full text of DOI:10.1016/j.ejmech.2011.07.013

European Journal of Medicinal Chemistry 46 (2011) 4696e4701
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis, pharmacological evaluation and docking studies of coumarin
derivatives
*
B. Sandhya, D. Giles , Vinod Mathew, Guru Basavarajaswamy, Rekha Abraham
Acharya & B.M Reddy College of Pharmacy, Soldevanahalli, Chikkabanavara Post, Bangalore 560090, Karnataka, India
a r t i c l e i n f o
a b s t r a c t
Article history:
We synthesized coumarin derivatives using various aromatic and heterocyclic amines, and tested the
target compound for its analgesic, anti-inflammatory, antimicrobial activities. Compounds 3l, 3m and 3n
showed significant anti-inflammatory, analgesic and antimicrobial activities. The synthesized
compounds, then docked on COX-2 to predict the binding affinity and orientation at the active site of the
receptor. It was found that the active compounds 3l, 3m and 3n intact mainly with Arg 44 amino acid,
which may be involved in COX-2 inhibition. The compounds which bind with Arg 44 have significant
anti-inflammatory activity. This could be due to the formation of more effective hydrogen bond with the
receptor. Comparing pharmacological activity and docking results, we conclude that heterocyclic
derivatives linked with nitrogen at 7-position of coumarin seem to be potentially active drug.
Ó 2011 Elsevier Masson SAS. All rights reserved.
Received 14 July 2010
Received in revised form
4 July 2011
Accepted 8 July 2011
Available online 19 July 2011
Keywords:
Docking
Analgesic
Coumarin
Antimicrobial
Anti-inflammatory
Cyclooxygenase
1. Introduction
various compounds bearing single substituent or more complicated
substituent in heterocyclic ring system mainly in 3-,4- and/or 7-
Non-steroidal anti-inflammatory drugs (NSAIDs) are mainly
used in the treatment of rheumatoid arthritis and various types of
inflammatory conditions. Most of NSAIDs exhibit their anti-
inflammatory effects by inhibiting cyclooxygenase (COX) which
catalyzes the bioconversion of arachidonic acid to prostaglandins.
However, inhibition of COXs may lead to undesirable side effects
such as gastric ulceration, bleeding and renal function suppression.
The two isozymes of COX involved in the prostaglandin biosyn-
thesis are COX-1 and COX-2. COX-2 is mainly involved in inflam-
mation condition [1e4]. Coumarin derivatives are anticoagulant
[5], and have been shown to exert its anti-inflammatory effects
through prostaglandin biosynthesis [6]. Coumarin, the potent basic
pharmacodynamic nucleus has been reported to possess a wide
variety of biological properties viz., anti-inflammatory [7e9],
analgesic [10,11] anticancer [12,13], antimicrobial [14], antifungal
[15], anthelmintic [16] and anticonvulsant activities [17,18].
position [6].
Encouraged by the above observations we synthesized newer 7-
substituted coumarin derivatives in hope of obtaining better anti-
inflammatory agents for a long period of time. We targeted to
study the structureeactivity relationship by altering different
amines and substitutions at the 7-position of the coumarin. Herein
we report the screening results of the anti-inflammatory, analgesic
and antimicrobial activity of the synthesized compounds.
2. Results and discussion
The synthetic route of the compounds is outlined in Scheme 1.
Bromination of 4-methyl-2-oxo-2H-chromene-7yl acetate (1) [19]
with bromine in acetic acid yielded 4-methyl-2-oxo-2H-chromen-
7ylbromoacetate (2). Further treatment of the compound 2 with
different
amines
yielded
4-methyl-2-oxo-2H-chromen-7yl
Due to the importance of coumarin derivatives and amino-
substituted derivatives several investigators have been investigating
substituted acetates (3aen). This reaction was carried out in pres-
ence of acetone as solvent. The progress of the reaction was being
monitored by thin layer chromatography (TLC) on silica-G (Merck)
coated glass plates, visualized by iodine vapor. IR, NMR and mass
spectral data confirmed the formation of the final compound. These
results will be reported in due course.
* Corresponding author. Dept. of Pharmaceutical Chemistry, Acharya
& B.M
Reddy College of Pharmacy, Soldevanahalli, Chikkabanavara Post, Bangalore
560090, Karnataka, India. Tel.: þ91 9448736917.
Anti-inflammatory and analgesic activity screening indicated
that some of the tested compounds showed good activity for the
E-mail address: sahayagiles@yahoo.com (D. Giles).
0223-5234/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.07.013

B. Sandhya et al. / European Journal of Medicinal Chemistry 46 (2011) 4696e4701
CH3
4697
CH3
O
Glacial CH3COOH
Br2
O
O
O
H3C
O
O
O
2
O
1
Br
1o & 2o amines
CH3
O
O
O
O
R
3a-n
Compound
R
Compound
R
h
i
j
k
l
m
n
p-OCH3-C6H5NH-
o-CH3-C6H5NH-
m-CH3-C6H5NH -
p-CH3-C6H5NH-
1,5-dihydro-4H-1,2,4-triazol-4-amino
1,3-benzothiazol-2-amino
1,3-thiazol-2-amino
a
b
c
d
e
f
C6H5NH-
o-NO2-C6H5NH-
m-NO2-C6H5NH-
p-NO2-C6H5NH-
o-Cl-C6H5NH-
p-Cl-C6H5NH-
o-OCH3-C6H5NH-
h
Scheme 1. Synthesis of coumarin derivatives.
long period. The results are specified in Tables 1 and 2. Compounds
3l, 3m and 3n showed moderate anti-inflammatory and analgesic
activities. But compound 3l is found to be active in 1 h of drug
administration then it starts decreasing after 1 h. It could be due to
metabolic instability of the compound. Derivatives 3c and 3h
showed moderate activity and started decreasing after 3 h. Results
revealed that, good anti-inflammatory and analgesic activity could
be due to the presence of heterocyclic substituent in the coumarin
In vitro study of antibacterial effects against Escherichia coli
(E. coli), Bacillus subtilis (B. subtilis) and antifungal activity against
Candida albicans (C. albicans), Aspergillus niger (A. niger) indicated
that not all the compounds exhibited good activity. Table 3 shows
the inhibitory effects of the compounds against these organisms. It
was evident from the screening results that the heterocyclic group
substituted in 7-position of coumarin nucleus increase activity.
To compare the binding affinity of the newly synthesized
compounds, we docked compounds in the empty binding site of
COX-2 (PDB entry 4COX), with its bound inhibitor indomethacin
which was shown in Fig. 1. Fig. 2 shows the compounds having
more hydrogen bonding with the receptor.
derivative. Replacement of
a heterocyclic ring with another
substituted phenyl group decreases the activity. This clearly indi-
cates that, analgesic and anti-inflammatory activity increases by
modification of heterocyclic ring in 7-position of coumarin nucleus.
Table 1
Anti-inflammatory activity of compounds (3aen).
Compound
Change in paw volume (in ml) after drug administration (ꢀSE)
Percentage inhibition of edema volume after
1 h
2 h
3 h
4 h
1 h
2 h
3 h
4 h
Standard
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
0.26 ꢀ 0.03
0.50 ꢀ 0.02
0.44 ꢀ 0.02
0.40 ꢀ 0.01
0.49 ꢀ 0.02
0.44 ꢀ 0.03
0.50 ꢀ 0.03
0.50 ꢀ 0.02
0.39 ꢀ 0.03
0.49 ꢀ 0.02
0.49 ꢀ 0.03
0.48 ꢀ 0.02
0.32 ꢀ 0.03
0.39 ꢀ 0.04
0.34 ꢀ 0.03
0.25 ꢀ 0.02
0.55 ꢀ 0.01
0.65 ꢀ 0.04
0.54 ꢀ 0.02
0.64 ꢀ 0.04
0.69 ꢀ 0.03
0.60 ꢀ 0.03
0.66 ꢀ 0.03
0.5 ꢀ 0.04
0.7 ꢀ 0.03
0.7 ꢀ 0.02
0.6 ꢀ 0.00
0.5 ꢀ 0.03
0.50 ꢀ 0.03
0.50 ꢀ 0.02
0.23 ꢀ 0.04
0.65 ꢀ 0.03
0.79 ꢀ 0.04
0.62 ꢀ 0.03
0.75 ꢀ 0.03
0.82 ꢀ 0.03
0.79 ꢀ 0.02
0.69 ꢀ 0.02
0.59 ꢀ 0.02
0.78 ꢀ 0.02
0.79 ꢀ 0.02
0.75 ꢀ 0.03
0.68 ꢀ 0.03
0.56 ꢀ 0.03
0.49 ꢀ 0.03
0.50 ꢀ 0.02
0.90 ꢀ 0.02
1.00 ꢀ 0.03
0.80 ꢀ 0.02
0.90 ꢀ 0.03
0.90 ꢀ 0.04
0.99 ꢀ 0.05
0.95 ꢀ 0.04
0.84 ꢀ 0.05
0.95 ꢀ 0.05
0.90 ꢀ 0.04
1.10 ꢀ 0.03
0.92 ꢀ 0.03
0.70 ꢀ 0.03
0.80 ꢀ 0.03
53.5
10.7
21.4
28.5
12.5
21.4
10.7
10.7
30.3
12.5
12.5
14.2
42.8
30.3
39.2
67.9
29.4
16.6
30.7
17.9
11.5
23.0
15.3
33.3
15.3
15.3
20.5
42.3
35.9
37.1
68.8
30.8
15.9
34.0
20.2
12.8
15.9
26.6
37.2
17.0
15.9
20.2
27.6
40.4
47.8
57.6
13.7
15.2
32.2
23.7
23.7
16.1
19.4
28.8
19.4
23.7
6.7
22.2
40.6
32.3

4698
B. Sandhya et al. / European Journal of Medicinal Chemistry 46 (2011) 4696e4701
Table 2
Analgesic activity of compounds (3aen).
Compounds
Mean number of
writhes in 30 min
% Decrease relative
to control
period after treatment ꢀ SE
Control
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
46.2 ꢀ 2.36
35.3 ꢀ 1.85
33.4 ꢀ 2.36
40.1 ꢀ 3.45
33.3 ꢀ 2.22
36.4 ꢀ 1.26
40.9 ꢀ 2.12
33.4 ꢀ 1.12
38.4 ꢀ 2.11
35.4 ꢀ 1.25
40.2 ꢀ 1.11
33.2 ꢀ 3.21
29.3 ꢀ 2.85
30.2 ꢀ 1.25
25.3 ꢀ 2.25
20.3 ꢀ 2.45
e
24
28
13
28
21
11
28
17
23
13
28
37
35
45
56
3m
3n
Std
Indomethacin (standard drug) reveals MolDock score
of ꢁ155.202 and form three hydrogen bonds between carboxylic
ꢀ
moiety and Tyr 130 with a bond distance of 3.20 A and another
two bonds with oxygen of methoxy group and carbonyl oxygen
ꢀ
with Asn 43 and Gln 42 with a bond distance of 3.57 and 3.29 A.
Compounds 3aen exhibited binding scores ranging from ꢁ135.58
to ꢁ159.65. Compounds 3l, 3m, and 3n with MolDock
score ꢁ135.58, ꢁ159.165 and ꢁ143.6 respectively, where they
have significant biological activities. Compound 3m is the most
active one among the series. It forms eight hydrogen bonds, three
hydrogen bonds with O-1 of coumarin moiety, two with Arg 44 of
ꢀ
ꢀ
distance 3.10 and 3.03 A and one hydrogen bond of distance 2.79 A
with Arg 469, O-2 of coumarin moiety bonded with Arg 469 with
ꢀ
a distance of 3.16 A, two hydrogen bonds between ester oxygen
and Ser 421, and Tyr 122 with a distance of 2.58 A and 3.23 A
respectively, one hydrogen bond between N of benzothiazole ring
with Asn 43 with a distance of 3.38 A, NH in aliphatic chain forms
one hydrogen bond with a distance of 2.79 A with Lys 468.
ꢀ
ꢀ
ꢀ
ꢀ
Docking studies on COX-2 reveals that the coumarin oxygen is
mainly responsible for binding with Arg 44 amino acid. Attach-
ment of nitrogen containing heterocyclic ring increases hydrogen
bond formation. Comparison of the docking result with that of
anti-inflammatory activity, heteroatom in the ring could be
responsible for the good anti-inflammatory activity.
3. Experimental
3.1. Chemistry
The reagents used in the present work were of analytical grade
and when necessary, were purified and dried by standard methods.
All melting points were determined on open capillaries using
Thermonik precision apparatus (Model-C-PMP-2, Mumbai, India)
and were uncorrected. The IR spectrum was recorded on Tensor 27
spectrophotometer, Bruker Optic (Germany) using ATR method. All
1H NMR spectra were recorded in Bruker spectrophotometer AMX-
400 (400 MHz), Bruker Optic (Germany) in CD3OD or DMSO.
Chemical shifts were reported in parts per million (
spectra were recorded using Agilent 5973n GC/MS.
d). All Mass
3.1.1. Synthesis of 4-methyl-2-oxo-2H-chromen-7yl bromo acetate
(2)
4-Methyl-2-oxo-2H-chromen-7yl acetate (2.18 g, 0.01 M) was
dissolved in 10 ml of glacial acetic acid; bromine (0.52 ml, 0.01 M)

B. Sandhya et al. / European Journal of Medicinal Chemistry 46 (2011) 4696e4701
4699
2.63 (s, 3H, CH3); 4.22 (s, 1H, NH); 4.2 (d, 2H, CH2); 6.3 (s, 1H, CH);
6.8e7.8 (m, 8H, AreH). GCeMS (m/z) 310 [M þ 1].
3.1.2.2. 4-Methyl-2-oxo-2H-chromen-7-yl
N-(o-nitrophenyl)glyci-
nate (3b). It is obtained by the reaction of bromo derivative 2 with
o-nitro aniline. Color: yellow powder, recrystallization solvent:
ethanol, yield: 83%, MP 203e205 ꢂC; IR (cmꢁ1): 3350 (NH), 3029
(CeH aryl), 2920 (CeH alkyl), 1774, 1729 (C]O), 1250 (CeO); 1H
NMR (DMSO-d6, d ppm): 2.6 (s, 3H, CH3); 4.1 (s, 1H, NH); 4.0 (d, 2H,
CH2); 6.2 (s, 1H, CH); 6.9e7.9 (m, 7H, AreH). GCeMS (m/z) 354 [Mþ].
3.1.2.3. 4-Methyl-2-oxo-2H-chromen-7-yl N-(m-nitrophenyl)glyci-
nate (3c). It is obtained by the reaction of bromo derivative 2 with
m-nitro aniline. Color: yellow powder, recrystallization solvent:
ethanol, yield: 80%, MP 210e213 ꢂC; IR (cmꢁ1): 3363 (NH), 3044
(CeH aryl), 2935 (CeH alkyl), 1772, 1710 (C]O), 1252 (CeO); 1H
Fig. 1. Binding mode of original ligand indomethacin into its binding site of COX-2. It
has MolDock score of ꢁ155.202 and forms three hydrogen bonds shown as green
dotted lines. (For interpretation of the references to color in this figure legend, the
reader is referred to the web version of this article.)
NMR (DMSO-d6,
d ppm): 2.8 (s, 3H, CH3); 4.3 (s, 1H, NH); 4.2 (d, 2H,
CH2); 6.2 (s, 1H, CH); 7.2e8.2 (m, 7H, AreH). GCeMS (m/z) 354 [Mþ].
3.1.2.4. 4-Methyl-2-oxo-2H-chromen-7-yl
N-(p-nitrophenyl)glyci-
nate (3d). It is obtained by the reaction of bromo derivative 2 with
p-nitro aniline. Color: yellow powder, recrystallization solvent:
ethanol, yield: 85%, MP 213e215 ꢂC; IR (cmꢁ1): 3352 (NH), 3030
(CeH aryl), 2921 (CeH alkyl), 1761, 1729 (C]O), 1256 (CeO); 1H
NMR (DMSO-d6, d ppm): 2.7 (s, 3H, CH3); 4.2 (s, 1H, NH); 4.0 (d, 2H,
CH2); 6.2 (s,1H, CH); 7.0e7.9 (m, 7H, AreH). GCeMS (m/z) 354 [Mþ].
3.1.2.5. 4-Methyl-2-oxo-2H-chromen-7-yl N-(o-chlorophenyl)glyci-
nate (3e). It is obtained by the reaction of bromo derivative 2 with o-
chloro aniline. Color: brown crystal, recrystallization solvent:
ethanol, yield: 66%, MP 185e187 ꢂC; IR (cmꢁ1): 3342 (NH), 3034
(CeH aryl), 2920 (CeH alkyl), 1763, 1725 (C]O), 1252 (CeO); 1H
NMR (DMSO-d6, d ppm): 2.7 (s, 3H, CH3); 4.2 (s, 1H, NH); 4.0 (d, 2H,
CH2); 6.1 (s, 1H, CH); 6.9e7.9 (m, 7H, AreH). GCeMS (m/z) 344 [Mþ].
Fig. 2. Binding mode of compound 3m into its binding site of COX-2. It has MolDock
score of 159.165 and forms eight hydrogen bonds shown as green dotted lines. (For
interpretation of the references to color in this figure legend, the reader is referred to
the web version of this article.)
3.1.2.6. 4-Methyl-2-oxo-2H-chromen-7-yl N-(p-chlorophenyl)glyci-
nate (3f). It is obtained by the reaction of bromo derivative 2 with
p-chloro aniline. Color: brown powder, recrystallization solvent:
ethanol, yield: 69%, MP 198e199 ꢂC; IR (cmꢁ1): 3344 (NH), 3033
(CeH aryl), 2922 (CeH alkyl), 1764, 1723 (C]O), 1252 (CeO); 1H
in glacial acetic acid mixture was added drop wise with constant
stirring. The reaction mixture was stirred at 40 ꢂC, for 4 h and
cooled. After cooling the reaction mixture was poured into crushed
ice. The precipitate was washed with water to remove excess of
bromine.
NMR (DMSO-d6, d ppm): 2.4 (s, 3H, CH3); 4.1 (s, 1H, NH); 4.0 (d, 2H,
CH2); 6.1 (s,1H, CH); 7.0e7.9 (m, 7H, AreH). GCeMS (m/z) 344 [Mþ].
3.1.2.7. 4-methyl-2-oxo-2H-chromen-7-yl N-(o-methoxyphenyl)gly-
cinate (3g). It is obtained by the reaction of bromo derivative 2 with
o-methoxy aniline. Color: brown crystal, recrystallization solvent:
ethanol, yield: 65%, MP 186e189 ꢂC; IR (cmꢁ1): 3346 (NH), 3034
(CeH aryl), 2924 (CeH alkyl), 1764, 1725 (C]O), 1254 (CeO); 1H
Color: pale brown, recrystallization solvent: ethanol, yield: 84%,
MP 118e120 ꢂC; IR (cmꢁ1): 3022 (CeH aryl), 2939 (CeH alkyl), 1621
(C]O), 1261 (CeO); 1H NMR (CD3OD,
d ppm): 2.0 (s, 3H, CH3); 4.0
(d, 2H, CH2); 6.0 (s, 1H, CH); 6.8e7.4 (m, 3H, AreH). GCeMS (m/z)
298 [M þ 1].
NMR (DMSO-d6,
d ppm): 2.4 (s, 3H, CH3); 3.5 (s, 3H, OCH3); 4.1 (s,
1H, NH); 4.0 (d, 2H, CH2); 6.1 (s, 1H, CH); 7.1e7.9 (m, 7H, AreH).
GCeMS (m/z) 339 [Mþ].
3.1.2. General method for the synthesis of 4-methyl-2-oxo-2H-
chromen-7yl substituted acetate (3aen)
3.1.2.8. 4-Methyl-2-oxo-2H-chromen-7-yl N-(p-methoxyphenyl)gly-
cinate (3h). It is obtained by the reaction of bromo derivative 2 with
p-methoxy aniline. Color: brown powder, recrystallization solvent:
ethanol, yield: 72%, MP 198e199 ꢂC; IR (cmꢁ1): 3344 (NH), 3033
(CeH aryl), 2922 (CeH alkyl),1764,1723 (C]O),1252 (CeO); 1H NMR
4-Methyl-2-oxo-2H-chromen-7yl bromo acetate (2.97 g,
0.01 M) and different amines (0.01 M) were dissolved in solvent
acetone. The reaction mixture was refluxed for 6 h. Finally the
reaction mixture was cooled and the contents were poured into
crushed ice. The solid separated out was filtered, washed with
water and recrystallized from ethanol.
(DMSO-d6, d ppm): 2.4 (s, 3H, CH3); 3.5 (s, 3H, OCH3); 4.1 (s,1H, NH);
4.0 (d, 2H, CH2); 6.1 (s,1H, CH); 7.0e8.0 (m, 7H, AreH). GCeMS (m/z)
339 [Mþ].
3.1.2.1. 4-Methyl-2-oxo-2H-chromen-7-yl N-phenylglycinate (3a). It
is obtained by the reaction of bromo derivative 2 with aniline.
Color: pale yellow powder, recrystallization solvent: ethanol, yield:
77%, MP 158e160 ꢂC; IR (cmꢁ1): 3341 (NH), 3031 (CeH aryl), 2923
3.1.2.9. 4-Methyl-2-oxo-2H-chromen-7-yl N-(o-methylphenyl)glyci-
nate (3i). It is obtained by the reaction of bromo derivative 2 with o-
methyl aniline. Color: yellow powder, recrystallization solvent:
ethanol, yield: 62%, MP 155e159 ꢂC; IR (cmꢁ1): 3341 (NH), 3032
(CeH alkyl), 1629 (C]O), 1266 (CeO); 1H NMR (DMSO-d6,
d ppm):

4700
B. Sandhya et al. / European Journal of Medicinal Chemistry 46 (2011) 4696e4701
(CeH aryl), 2929 (CeH alkyl),1761,1721 (C]O),1251 (CeO); 1H NMR
(DMSO-d6, ppm): 2.4 (s, 3H, CH3); 2.0 (s, 3H, CH3); 4.0 (s, 1H, NH);
3.7 (d, 2H, CH2); 6.1 (s, 1H, CH); 7.1e8.0 (m, 7H, AreH). GCeMS (m/z)
324 [M þ 1].
(‘0’ h) and after 1 h, 2 h, 3 h and 4 h, respectively, by using
plethysmograph. The amount of edema in the drug-treated groups
was compared in relation to the control group with the corre-
sponding time intervals. The results were expressed as percentage
inhibition of edema over the untreated control group and repre-
sented in Table 1.
d
3.1.2.10. 4-Methyl-2-oxo-2H-chromen-7-yl N-(m-methylphenyl)gly-
cinate (3j). It is obtained by the reaction of bromo derivative 2 with
m-methyl aniline. Color: yellow powder, recrystallization solvent:
ethanol, yield:64%, MP 168e169 ꢂC;IR (cmꢁ1): 3343(NH), 3032(CeH
aryl), 2920 (CeH alkyl), 1761, 1727 (C]O), 1251 (CeO); 1H NMR
(DMSO-d6, d ppm): 2.4 (s, 3H, CH3); 1.9 (s, 3H, CH3); 4.2 (s,1H, NH); 4.1
(d, 2H, CH2); 6.0 (s,1H, CH); 7.0e8.0 (m, 7H, AreH). GCeMS (m/z) 324
[M þ 1].
3.2.2. Analgesic activity
Acetic acid writhing test was performed on mice for calcu-
lating analgesic activity. Groups of six mice (body weight
20e30 g) of both sexes, pregnant female excluded, were given
a dose of a test compound. Thirty minutes later, the animals were
injected intraperitoneally with 0.25 ml/mouse of 0.5% acetic acid
solution and writhes were counted during the following 30 min.
The mean number of writhes for each experimental group and
percent decrease compared with control group (mice not treated
with test compounds) were calculated. The results were
expressed in percentage decrease relative to control and tabu-
lated in Table 2.
3.1.2.11. 4-Methyl-2-oxo-2H-chromen-7-yl N-(p-methylphenyl)glyci-
nate (3k). It is obtained by the reaction of bromo derivative 2 with
p-methyl aniline. Color: brownish yellow powder, recrystallization
solvent: ethanol, yield: 64%, MP 188e189 ꢂC; IR (cmꢁ1): 3345 (NH),
3035 (CeH aryl), 2923 (CeH alkyl), 1764, 1723 (C]O), 1252 (CeO);
1H NMR (DMSO-d6,
d ppm): 2.3 (s, 3H, CH3); 2.0 (s, 3H, CH3); 4.1 (s,
1H, NH); 4.0 (d, 2H, CH2); 6.1 (s, 1H, CH); 7.2e8.1 (m, 7H, AreH).
GCeMS (m/z) 324 [M þ 1].
3.2.3. Antimicrobial activity
The newly synthesized compounds were tested for their anti-
bacterial against E. coli (Gram negative), B. subtilis (Gram positive)
and antifungal activity against C. albicans, A. niger. The results were
compared to Amikacin, Vancomycin for antibacterial activity and
Griseofulvin for antifungal activity as a reference drug. Experi-
mental results were listed in Table 3.
3.1.2.12. 4-Methyl-2-oxo-2H-chromen-7-yl N-(1,5-dihydro-4H-1,2,4-
triazol-4-yl)glycinate (3l). It is obtained by the reaction of bromo
derivative
2 with 1,5-dihydro-4H-1,2,4-triazol-4-amine. Color:
reddish powder, recrystallization solvent: ethanol, yield: 62%, MP
210e212 ꢂC; IR (cmꢁ1): 3348 (NH), 3358 (NH), 3034 (CeH aryl),
2923 (CeH alkyl), 1763, 1722 (C]O), 1250 (CeO); 1H NMR (DMSO-
3.3. Molecular modeling and docking studies
d6, d ppm): 2.4 (s, 3H, CH3); 3.4 (s, 2H, CH2); 4.0 (d, 2H, CH2); 4.1 (s,
1H, NH); 4.4 (s, 1H, NH); 6.1 (s, 1H, CH); 7.2e8.1 (m, 4H, AreH).
To assess the anti-inflammatory behavior of our coumarin
derivatives on structural basis, automated docking studies were
carried out using Molegro Virtual Docker program, the scoring
functions and hydrogen bonds formed with the surrounding amino
acids are used to predict their binding modes, their binding affin-
ities and orientation of these compounds at the active site of the
COX-2 enzyme. The protein-ligand complex was constructed based
on the X-ray structure (PDB entry 4COX) COX-2 with its bound
inhibitor of Indomethacin. The scoring functions of the compounds
were calculated with reference to indomethacin.
GCeMS (m/z) 302 [Mþ].
3.1.2.13. Synthesis of 4-methyl-2-oxo-2H-chromen-7-yl N-1,3-
benzothiazole-2yl-glycinate (3m). It is obtained by the reaction of
bromo derivative 2 with 1,3-benzothiazole-2-amine. Color: yellow
powder, recrystallization solvent: ethanol, yield: 56%, MP
198e200 ꢂC; IR (cmꢁ1): 3333 (NH), 3031 (CeH aryl), 2921 (CeH
alkyl), 1752, 1722 (C]O), 1251 (CeO); 1H NMR (DMSO-d6,
d ppm):
2.1 (s, 3H, CH3); 4.0 (s, 2H, CH2); 4.3 (s, 1H, NH); 5.8 (s, 1H, CH);
6.9e8.1 (m, 7H, AreH). GCeMS (m/z) 366 [Mþ].
Acknowledgment
3.1.2.14. Synthesis of 4-methyl-2-oxo-2H-chromen-7-yl N-1,3-
thiazol-2-ylglycinate (3n). It is obtained by the reaction of bromo
derivative 2 with 1,3-thiazole-2-amine. Color: pale yellow powder,
recrystallization solvent: ethanol, yield: 67%, MP 198e200 ꢂC; IR
(cmꢁ1): 3306 (NH), 3041 (CeH aryl), 2902 (CeH alkyl), 1761, 1721
The encouragement received from the Principal and Chairman,
Acharya & B.M. Reddy College of Pharmacy is gratefully acknowl-
edged. We also thank Dr. Rene Thomsen for providing Molegro trial
license.
(C]O), 1570 (C]N) 1251 (CeO); 1H NMR (DMSO-d6,
d ppm): 2.4 (s,
3H, CH3); 4.0 (d, 2H, CH2); 4.1 (s,1H, NH); 6.1 (s,1H, CH); 7.2e8.1 (m,
5H, AreH). GCeMS (m/z) 316 [Mþ].
References
3.2. Pharmacology
[1] J.R. Vane, R.M. Botting, Inflamm. Res. 47 (1998) 78e87.
[2] J. Van Ryn, G. Trummlitz, M. Pairet, Curr. Med. Chem. 7 (2000) 1145e1161.
[3] J.S. Carter, Expert Opin. Ther. Pat. 10 (2000) 1011e1020.
[4] M. Beuck, Angew. Chem. Int. Ed. 38 (1999) 631e633.
[5] R.B. Arora, C.N. Mathur, Br. J. Pharmacol. 20 (1963) 29e35.
[6] A.A.M. Eissa, N.A.H. Farag, G.A.H. Soliman, Biorg. Med. Chem. 17 (2009)
5059e5070.
[7] K.C. Fylaktakidou, D.J. Hadjipavlou-Litina, K.E. Litinas, D.N. Nicolaides, Curr.
Pharm. Des 10 (2004) 3813e3833.
[8] M. Ghate, D. Manohar, V. Kulkarni, R. Shobha, S.Y. Kattimani, Eur. J. Med.
Chem. 38 (2003) 297e302.
[9] M. Ghate, R.A. Kusanur, M.V. Kulkarni, Eur. J. Med. Chem. 40 (2005) 882e887.
[10] L. Bonsignore, F. Cottiglia, S.M. Lavagna, G. Loy, D. Secc, Farmaco 53 (1998)
2597e2605.
[11] R.S. Keri, K.M. Hosamani, R.V. Shingalapur, M.H. Hugar, Eur. J. Med. Chem. 45
(2010) 2597e2605.
3.2.1. Anti-inflammatory activity
Anti-inflammatory activity of the synthesized compounds
(3aen) was evaluated by carrageenan-induced acute paw edema
method. Male Wistar albino rats weighing 150e200 g were
divided into six animals in each group. One group was treated with
0.1 ml of 1% gum acacia suspension orally (control), second group
was administered with a dose of 20 mg/kg of the suspension of
Indomethacin (standard) and the other groups (test compounds)
were treated with 20 mg/kg of the suspension of test compounds.
After 30 min the animals were injected with 0.1 ml of 1% carra-
geenan in normal saline subcutaneously to the sub-plantar region
of right hind paw. The paw volume was measured immediately
[12] L.S. Via, O. Gia, S.M. Magno, L. Santana, M. Teijeira, E. Uriarte, J. Med. Chem. 42
(1999) 4405e4413.

B. Sandhya et al. / European Journal of Medicinal Chemistry 46 (2011) 4696e4701
4701
[13] S.S. Bhattacharyya, S. Paul, S.K. Mandal, A. Banerjee, N. Boujedaini, A.R. Khuda-
Bukhsh, Eur. J. Pharmacol. 614 (2009) 128e136.
[16] B.H. Lee, M.F. Clothier, F.E. Dutton, G.A. Conder, S.S. Johnson, Bioorg. Med.
Chem. Lett. 8 (1998) 3317e3320.
[14] G.R. Jani, K.B. Vyas, Z. Franco, E-J. Chem 6 (2009) 1228e1232.
[15] S. Sardari, Y. Mori, K. Horita, R.G. Micetich, S. Nishibe, M. Daneshtalab, Bioorg.
Med. Chem. 7 (1999) 1933e1940.
[17] M.A. Bhat, N. Siddiqui, S.A. Khan, Indian J. Pharm. Sci. 68 (2006) 120e124.
[18] N. Siddiqui, M.F. Arshad, S.A. Khan, Acta Pol. Pharm. 66 (2009) 161e167.
[19] A. Russell, J.R. Frye, Org. Synth. 21 (1941) 22e27.