Synthesis of 6-aminomethyl derivatives of benzopyran-4-one with dual biological properties: Anti-inflammatory-analgesic and antimicrobial

Article abstract of DOI:10.1016/j.ejmech.2009.08.001

A series of 6-aminomethyl-2-aryl-1-benzopyran-4-one derivatives (10-24) were synthesized. The compounds were tested for anti-inflammatory, analgesic, ulcerogenic and lipid peroxidation actions. Among the tested compounds, six compounds 11, 13, 16, 18, 21 and 23 showed higher degree of anti-inflammatory activity (>75% activity of standard drug ibuprofen). In addition to remarkable anti-inflammatory activity, analgesic activity was found to be comparable with that of the standard drug ibuprofen. Compounds 16 and 21 showed a significant GI protection (with respect to ulcerogenesis) and a marked decrease in lipid peroxidation values whereas compounds 11 and 16 were found to possess antimicrobial activity against Staphylococcus aureus, Escherichiacoli, Rhizopus oryza and Penicillum citrum with an MIC of 10 μg/mL.

Full text of DOI:10.1016/j.ejmech.2009.08.001

European Journal of Medicinal Chemistry 44 (2009) 4896–4903
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis of 6-aminomethyl derivatives of benzopyran-4-one with dual biological
properties: Anti-inflammatory-analgesic and antimicrobial
,
b
,
,
,
,4
S.M. Hasan a, M.M. Alam b , Asif Husain 1, Suruchi Khanna c 2, Mymoona Akhtar b 3, M.S. Zaman b
*
a Department of Pharmacy, College of Health Sciences, Al Jouf University, Sakaka, Al Jouf, Saudi Arabia
b Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hamdard University, New Delhi 110 062, India
c Department of Pharmacology, Faculty of Pharmacy, Hamdard University, New Delhi 110 062, 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 6-aminomethyl-2-aryl-1-benzopyran-4-one derivatives (10–24) were synthesized. The
Received 25 March 2009
Received in revised form
15 July 2009
Accepted 3 August 2009
Available online 6 August 2009
compounds were tested for anti-inflammatory, analgesic, ulcerogenic and lipid peroxidation actions.
Among the tested compounds, six compounds 11, 13, 16, 18, 21 and 23 showed higher degree of anti-
inflammatory activity (>75% activity of standard drug ibuprofen). In addition to remarkable anti-
inflammatory activity, analgesic activity was found to be comparable with that of the standard drug
ibuprofen. Compounds 16 and 21 showed a significant GI protection (with respect to ulcerogenesis) and
a marked decrease in lipid peroxidation values whereas compounds 11 and 16 were found to possess
antimicrobial activity against Staphylococcus aureus, Escherichiacoli, Rhizopus oryza and Penicillum citrum
Keywords:
Flavone
Anti-inflammatory
Analgesic
with an MIC of 10 mg/mL.
Ó 2009 Elsevier Masson SAS. All rights reserved.
Ulcerogenic
Lipid peroxidation
Antimicrobial
1. Introduction
patients with prior history of peptic ulcer disease, patients with
impaired liver or kidney functions and patients taking anticoagu-
lants, corticosteroids, etc. concurrently. Hence, there is a pressing
need for the drugs having both anti-inflammatory and antimicro-
bial activities, both from the pharmacoeconomic as well as the
patient compliance point of view [3].
Substituted flavonoids are an important bioactive molecules
possessing antiplatelet aggregation [4], antihypertensive [5,6],
antifungal [7,8], anti-inflammatory [9,10], antitumor [11–13], anti-
malarial [14,15], anti-HIV [16], hypoglycemic [17,18], antibacterial
[19], analgesic [20], antioxidant [21,22] properties. Although not
fully understood, several cellular mechanisms have been proposed
to explain the in-vitro and in-vivo anti-inflammatory activity of
flavonoids [23]. One of the important mechanism is modulation of
the expression of pro-inflammatory genes such as cyclooxygenase
(COX), lipoxygenase (LOX), nitric oxide synthases and several
pivotal cytokines, via transcription factors (nuclear factor-kappa B
and mitogen-activated protein kinase signaling); and thus
decreasing the levels of prostanoids and leukotrienes.
Nonsteroidal anti-inflammatory drugs (NSAIDs) have been
recognized as vital therapeutic agents for the alleviation of pain and
inflammation associated with a numerous pathologic conditions
viz. arthritis, bursitis, tendinitis. However, chronic administration of
NSAIDs has been associated with clinically significant complica-
tions such as gastrointestinal (GI) symptoms including mucosal
damage, bleeding, nausea, heartburn, dyspepsia, and abdominal
pain; renal toxicity, etc. [1,2]. Polytherapy for inflammatory
conditions associated with microbial infections increases the risk
for developing NSAID-related complications especially in elderly,
* Corresponding author. Tel.: þ91 11 26059681/88x5645, þ91 9717861119
(mobile); fax: þ91 11 26059663.
E-mail addresses: misbahhasan@yahoo.com (S.M. Hasan), drmmalam@gmail.
com, hamlucky@rediffmail.com (M.M. Alam), drasifhusain@yahoo.com (A. Husain),
myzoon@rediffmail.com (M. Akhtar), shaqiq@gmail.com (M.S. Zaman).
URL: http://suranv@rediffmail.com
1
The activated inflammatory cells could be involved in the
pathogenesis of mucosal damage. Gastric mucosal cells metabolise
arachidonic acid via both the LOX and COX pathways [23] and the
presence of inflammatory cells infiltrate in the gastric mucosa
results in the production of large quantities of oxygen derived free
radicals that could cause cell damage and leads ultimately to
Tel.: þ91 11 26059681, 26059688x5647, þ91 9891116086 (mobile); fax: þ91 11
26059663.
2
Tel.: þ91 11 26059681, 26059688x5667; fax: þ91 11 26059663.
3
Tel.: þ91 11 26059681, 26059688x5645, þ91 9891369482 (mobile); fax þ91 11
26059663.
4
Tel.: þ91 11 26059681, 26059688x5660, þ91 99900663405 (mobile); fax: þ91
11 26059663.
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.08.001

S.M. Hasan et al. / European Journal of Medicinal Chemistry 44 (2009) 4896–4903
4897
R'
R'
OH
O
(i)
OH
O
O
O
(ii)
CH3
1-(2-hydroxyphenyl)-1-ethanone
1:R'=4-OCH3; 2:R'=3,4-(OCH3)2; 3:R'=2-Cl
1,3-Diaryl-2-propen-1-one (1-3)
4:R'=4-OCH3; 5:R'=3,4-(OCH3)2; 6:R=2-Cl
2-Aryl-1-benzopyran-4-one (4-6)
10:R=N(CH3)2; R'=4-OCH3
11:R=morpholine; R'=4-OCH3
12:R=toluidino; R'=4-OCH3
13:R=piperazinyl; R'=4-OCH3
14:R=sulfonamide; R'=4-OCH3
15:R=N(CH3)2; R'=3,4-(OCH3)2
(iii)
20:R=N(CH3)2; R'=2-Cl
16:R=morpholine; R'=3,4-(OCH3)2
17:R = toluidino; R'= 3,4-(OCH3)2
18:R=piperazinyl; R' = 3,4-(OCH3)2
19:R=sulfonamide; R'=3,4-(OCH3)2
21:R=morpholine; R'=2-Cl
22:R=toluidino; R' = 2-Cl.
23:R=piperazinyl; R'=2-Cl
24:R=sulfonamide; R'=2-Cl
R'
O
(iv)
R'
O
ClH2C
O
RN
7:R'=4-OCH3; 8:R'=3,4-(OCH3)2; 9:R'=2-Cl
O
6-Chloromethyl-2-aryl-1-benzopyran-4-one (7-9)
6-Aminomethyl-2-aryl-1-benzopyran-4-one (10-24)
Reagents and reaction conditions: (i) ArCHO, KOH, room temperature; (ii) DMSO, I2, reflux;
(iii) HCl, CH3COOH, HCHO, 00C; (iv) RNH2, steam bath
Scheme 1.
mucosal injury. Flavonoid’s antioxidant and free radical scavenging
activity largely depends upon their molecular structure.
The IR spectral data of all the compounds showed two peaks each
around 3060 cmꢀ1 and 1690 cmꢀ1 indicating the presence of olefinic
linkageandconjugatedcarbonylgroupofchromoneringrespectively.
1H NMR and 13C NMR spectral data of all the compounds
Compounds containing an amino group in the structure occupy
a prominent position in medicinal chemistry due to a number of
physiological actions; and its removal will lead to a virtual loss of
their activity [24]. We therefore, envisaged incorporating an amino
link attached to the flavone moiety thereby improving the known
bioactions of flavonoids. Thus, the chloromethylation (at position-6)
followed by substitution of the chlorine of the chloromethyl group
by several amines was carried out. The synthesized derivatives were
then tested for antimicrobial, anti-inflammatory and analgesic
actions; for the GI protection from ulcerogenesis and for lipid per-
oxidation (LPO) effect. The effect of molecular variations on the anti-
inflammatory and antimicrobial activities of flavonoid nucleus has
also been reported.
showed characteristic peak at appropriate d-values. Mass spectral
data of 6-aminomethyl-2-aryl-1-benzopyran-4-one gave Mþ peak
in reasonable intensities. The molecular ion or other related ions
produced the appropriate isotopic abundances due to presence of
chlorine atom(s). The analytical data has been mentioned in Table 1.
In order to support the assignments made through one-dimen-
sional NMR, HMBC was recorded for compound-8 as representative
and the noticed correlations are given inTable 2 which supports that
the chloromethylation takes placeat position-6of the flavonoid ring.
3. Pharmacological results and discussion
2. Chemistry
3.1. Anti-inflammatory activity
The method utilized for the synthesis of 6-aminomethyl-2-aryl-
1-benzopyran-4-one derivatives 10–24 has been outlined in Scheme
1. The arylketones and arylaldehydes were commercially available
and the 1,3-diaryl-2-propen-1-one 1–3 and 2-aryl-1-benzopyran-4-
one 4–6 were easily prepared by following the previously reported
methods in highyield [25]. The obtained 2-aryl-1-benzopyran-4-one
derivatives 4–6 were chloromethylated (replacement of a hydrogen
atom by a chloromethyl group) by reaction with paraformaldehyde
and hydrogen chloride in presence of acetic acid at position-6 to give
6-chloromethyl-2-aryl-1-benzopyran-4-one derivatives 7–9. Chlor-
omethylation is similar in some respect to that of Friedel Craft’s
reaction. The mechanism of chloromethylation is based upon an
electrophilic attack on an aromatic ring to give the benzylic alcohol,
which is then converted into the chloromethyl derivative by
hydrogen chloride. The chloromethylated benzopyran-4-ones
derivatives were further condensed with different amines to give
6-aminomethyl-2-aryl-1-benzopyran-4-one derivatives 10–24.
Compounds 7–24 were tested in-vivo for their anti-inflamma-
tory properties by carrageenan-induced rat paw edema method
[26]. All the compounds were administered orally (p.o.) and assayed
at the dose level of 20 mg/kg of body weight. Ibuprofen was used as
a standard drug for comparison. The results of the pharmacological
evaluation are enlisted in Table 3. Six of the eighteen tested
compounds exhibited statistically significant anti-inflammatory
activity with respect to standard drug. The maximum activity was
shown by the compounds bearing morpholine moiety as an amino
linkage i.e. compounds 16 and 21 with 81.48% and 82.51% inhibition
respectively. In addition, four compounds, 11, 13, 18 and 23 showed
75.30%, 69.13%, 72.63% and 73.86% inhibition respectively. From the
above pharmacological results following remarks can be made.
ꢁ With compounds bearing morpholine linkage at 6-position of
benzopyran-4-one the best result was shown by compound 21
with a chloro substitution at ortho position on the phenyl ring.

4898
S.M. Hasan et al. / European Journal of Medicinal Chemistry 44 (2009) 4896–4903
Table 1
Physical constants of 6-substitutedmethyl-2-aryl-1-benzopyran-4-one derivatives.
3
4
R'
Phenyl ring
2
1
5
1
8
O
Chromone ring
7
6
2
4
3
6
RH2C
5
O
Comp. no.
R
R’
M.pt. (ꢂC)
Yield (%)
Rf
Molecular formula
7
8
9
10
Cl
Cl
Cl
4-OCH3
(OCH3)3,4
2-Cl
170
171
178
156
46
52
38
44
0.91
0.70
0.82
0.68
C17H13O3Cl
C18H15O4Cl
C16H10O2Cl2
C19H19O3N
4-OCH3
CH3
CH3
N
11
12
4-OCH3
4-OCH3
146
136
48
46
0.72
0.68
C21H21O4N
N
O
C24H21O3N
N
H
CH3
13
14
4-OCH3
4-OCH3
140
160
50
52
0.84
0.92
C21H22O3N2
N
NH
C23H20O5N2S
N
H
SO2
NH2
15
(OCH3)3,4
166
42
0.88
C20H20O4N
CH3
CH3
N
16
17
(OCH3)3,4
(OCH3)3,4
156
150
54
38
0.80
0.86
C22H23O5N
N
O
C25H23O4N
N
H
CH3
18
19
(OCH3)3,4
(OCH3)3,4
150
178
42
46
0.84
0.87
C22H24O4N2
N
NH
C24H22O6N2S
N
H
SO2
NH2
20
2-Cl
156
48
0.75
C18H15O2NCl
CH3
CH3
N
21
22
2-Cl
2-Cl
148
162
52
50
0.73
0.87
C20H18O3NCl
C23H18O2NCl
N
O
N
H
CH3

S.M. Hasan et al. / European Journal of Medicinal Chemistry 44 (2009) 4896–4903
4899
Table 1 (continued)
Comp. no.
23
R
R’
M.pt. (ꢂC)
142
Yield (%)
54
Rf
Molecular formula
C20H19O2N2Cl
2-Cl
0.79
N
NH
24
2-Cl
172
48
0.81
C22H17O4N2SCl
N
SO2
NH2
H
* Rf values for compounds 2–13 in solvent system (toluene:ethylacetate:formic acid, 5:4:1) and for compound 14–18 in solvent system (petrol:toluene:ethylacetate, 10:5:3); **
The micro analysis values for C, H and N were within ꢃ4% of the theoretical values.
A para substitution on the phenyl ring with methoxy group
(compound 11) decreases activity whereas inhibition increases
with an additional methoxy group on phenyl ring (3,4 dime-
thoxy) (compound 16).
ꢁ Presence of piperazinyl moiety at 6-position of benzopyran-4-
one showed good activity. Compound 23 with a chloro
substitution at ortho position on phenyl ring showed 73.86%
inhibition. Presence of methoxy group on the phenyl ring
(compound 13) decreases the activity to 68.93% which
increases to 72.22% with an additional methoxy group on
phenyl ring (compound 16).
electrons from the lipids in cell membrane and consequently
damages the cell. It often affects polyunsaturated fatty acids
forming malondialdehyde (MDA).
The colorimetric reaction of thiobarbituric acid (TBA) with MDA,
a secondary product of LPO has been widely adopted as a sensitive
assay method for measuring LPO in animal tissues. It is used as an
index for the extent to which LPO has progressed. Since the assay
procedure estimates the amount of TBA reactive substances e.g.
MDA, it is also referred to as Thiobarbituric acid reactive substance
(TBARS) test [29].
Therefore, an attempt was made to correlate the decrease in
ulcerogenic activity of the compounds with that of lipid perox-
idation. All the compounds screened for ulcerogenic activity were
also analyzed for LPO. The LPO was measured as nmoles of MDA/mg
of protein using Ohkawa et al. method [30]. Ibuprofen exhibited
high lipid peroxidation 0.608 ꢃ 0.001 nmol MDA/mg of protein
whereas control group showed 0.238 ꢃ 0.002. It was found that all
the aminomethyl derivatives of benzopyran-4-one showing less
ulcerogenic activity also showed reduction in lipid peroxidation
(Table 4). Thus, these studies showed that synthesized compounds
have inhibited the induction of gastric mucosal lesions and the
results further suggested that their protective effect might be
related to the inhibition of lipid peroxidation in gastric mucosa.
ꢁ The presence of sulfanilamide as amino linkage showed
decrease in anti-inflammatory activity (58–60% inhibition) and
the activity decreases further when the group is replaced by
p-toluidine or dimethylamine.
Test compounds exhibiting significant anti-inflammatory
activity 11, 13, 16, 18, 21 and 23 were evaluated for their analgesic,
ulcerogenic and LPO actions.
3.2. Analgesic activity
The compounds that exhibited above 75% of anti-inflammatory
activity of ibuprofen were evaluated for analgesic effects using
acetic acid-induced writhing method [27].
3.5. Antimicrobial activity
The result of analgesic activity (Table 4) indicates that the
compounds 16 and 21 showed 53.61% and 54.81% protection
against acetic acid-induced writhing and were comparable to
standard ibuprofen (65.06%). Compounds 11 and 23 also showed
good analgesic activity (50.80% and 48.39%).
Structure–activity relationship showed that the morpholine and
piperazinyl derivatives of benzopyran-4-one were good anti-inflam-
matory agents with analgesic activity equal to that of ibuprofen.
The compounds were evaluated for their antimicrobial activity
using turbidity method [31] against Staphylococcus aureus (ATCC-
29737) representing Gram-positive bacteria, Escherichia coli (ATCC-
8739) representing Gram negative bacteria and Rhizopus oryza
(NRRL-21498) and Penicillum citrum (NCIM-768) representing
fungi. The results of antimicrobial effect of all the tested
compounds were reported as minimal inhibitory concentrations
(MICs,
mg/mL), and are shown in Table 5. The results revealed that
most of the newly synthesized compounds exhibited promising
3.3. Acute ulcerogenesis
antifungal activities. Compounds 11 and 16 were most active
against both bacterial and fungal strain with MIC of 10
However, compound 19 was active against fungal strain with MIC of
mg/mL.
The compounds which were screened for analgesic activity were
further tested for their acute ulcerogenic activity. Compounds 11,
13, 16, 18, 21 and 23 were tested according to the method reported
by Cioli et al. [28]. The tested compounds showed low ulcerogenic
activity ranging from 0.1 ꢃ0.1 to 0.4 ꢃ 0.4 whereas the standard
drug ibuprofen showed high severity index of 0.9 ꢃ 0.36. The
maximum reduction in ulcerogenic activity (0.1 ꢃ0.1) was found in
the morpholine derivatives of benzopyran-4-one. The other tested
compounds also exhibited better GI safety profile as compared to
the standard drug ibuprofen. Results are tabulated in Table 4.
10
10
m
m
g/mL. Compound 7 was active against S. aureus with MIC of
g/mL. Compounds 14 and 15 were active against R. oryza with
MIC of 10
MIC of 10
m
m
g/mL. Compound 18 was most active against E. coli with
g/mL.
4. Conclusion
Eighteen new benzopyran-4-one derivatives were synthesized
and screened for anti-inflammatory, analgesic, ulcerogenic, lipid
peroxidation and antimicrobial activities. It is interesting to note
that six aminomethyl derivatives of benzopyran-4-one were found
to have anti-inflammatory properties comparable to standard drug
ibuprofen. When these compounds were subjected to analgesic
3.4. Lipid peroxidation (LPO)
LPO refers to the oxidative degradation of lipids. This process
proceeds by free radical chain reaction in which free radicals steal

4900
S.M. Hasan et al. / European Journal of Medicinal Chemistry 44 (2009) 4896–4903
Table 2
Table 3
The data of 13C and 1H and HMBC correlations for compound-8.
Anti-inflammatory activity of the synthesized compounds 7–24.
Compound Paw volume ꢃ SEMa
% Inhibition ꢃ SEMb
12
OMe
After 2 h
After 3 h
0.81 ꢃ 0.02
After 2 h
After 3 h
13
OMe
3'
Control
Ibuprofen
7
8
10
11
12
13
14
15
16
17
18
19
20
21
22
0.75 ꢃ 0.01
–
–
2'
1'
0.14 ꢃ 0.01*** 0.085 ꢃ 0.02*** 80.88 ꢃ 2.02
89.50 ꢃ 2.56
4'
5'
0.50 ꢃ 0.03***
0.5 ꢃ 0.02***
0.48 ꢃ 0.02***
0.28 ꢃ 0.02***
0.61 ꢃ 0.02**
0.45 ꢃ 0.02***
0.56 ꢃ 0.03***
0.52 ꢃ 0.02***
0.28 ꢃ 0.00***
0.61 ꢃ 0.03**
0.34 ꢃ 0.01***
0.54 ꢃ 0.02***
0.47 ꢃ 0.01***
0.26 ꢃ 0.01***
0.60 ꢃ 0.02**
0.33 ꢃ 0.02***
0.50 ꢃ 0.02***
0.49 ꢃ 0.04*** 32.22 ꢃ 5.04*** 38.68 ꢃ 5.85***
0.41 ꢃ 0.02*** 33.33 ꢃ 3.15*** 49.38 ꢃ 2.68***
1
O
8
5
9
0.38 ꢃ 0.03*** 36 ꢃ 3.31***
53.08 ꢃ 3.96***
7
6'
2
0.2 ꢃ 0.01*** 62.66 ꢃ 3.24*** 75.30 ꢃ 2.01**
0.39 ꢃ 0.02*** 18.66 ꢃ 3.83*** 51.02 ꢃ 2.75***
0.25 ꢃ 0.01*** 39.55 ꢃ 3.27*** 68.93 ꢃ 1.75***
0.32 ꢃ 0.02*** 25.33 ꢃ 4.35*** 60.49 ꢃ 2.29***
0.39 ꢃ 0.03*** 29.77 ꢃ 3.34*** 51.02 ꢃ 4.10***
0.15 ꢃ 0.00*** 61.77 ꢃ 1.17*** 80.86 ꢃ 1.04*
0.39 ꢃ 0.01*** 18.66 ꢃ 4.10*** 50.82 ꢃ 1.36***
3
4
11
ClH2C
10
6
O
Carbon number
13C (
d
)
1H(
d
)
HMBC correlation (from C to H)
0.22 ꢃ 0.01*** 54 ꢃ 2.37***
72.22 ꢃ 1.82***
2
3
4
5
6
7
8
9
10
11
12
13
1’
2’
3’
4’
5’
6’
162.4
105.6
177.2
107.5
141.4
123.7
119.6
155.5
124.2
65.5
–
C-2/H-2’; C-2/H-6’; C-2/H-3
–
C-4/H-3; C-4/H-5
C-5/H-7; C-5/H-11
C-6/H-7; C-6/H-5; C-6/H-11
C-7/H-5; C-7/H-8; C-7/H-11
C-8/H-7
0.32 ꢃ 0.02*** 27.11 ꢃ 3.99*** 60.49 ꢃ 2.99***
0.37 ꢃ 0.03*** 36.22 ꢃ 2.58*** 54.32 ꢃ 4.01***
0.14 ꢃ 0.00*** 64.44 ꢃ 1.36*** 82.51 ꢃ 1.07*
0.38 ꢃ 0.01*** 19.77 ꢃ 3.38*** 52.67 ꢃ 1.30***
7.04 (s, 1H)
–
8.28 (d, 1H)
–
7.70 (d, 1H)
7.49 (m, 1H)
–
–
4.66 (s, 2H)
3.99 (s, 3H)
3.99 (s, 3H)
–
7.24 (d, 1H)
–
23
24
0.21 ꢃ 0.01*** 56 ꢃ 2.92***
73.86 ꢃ 1.87***
0.33 ꢃ 0.02*** 32.22 ꢃ 2.78*** 58.23 ꢃ 2.84***
C-9/H-5; C-9/H-7; C-9/H-8
C-10/H-3; C-10/H-5; C-10/H-8
C-11/H-5; C-11/H-7
C-12/H-2’
C-13/H-5’
C-1’/H-3; C-1’/H-2’; C-1’/H-6’
C-2’/H-6’
*p < 0.05; **p < 0.01; ***p < 0.001.
a
Relative to their respective control and data were analyzed by one-way ANOVA
followed by Turkey test for n ¼ 6.
b
55.3
56.8
Relative to the standard (Ibuprofen) and data were analyzed by one-way ANOVA
followed by Turkey test for n ¼ 6.
121.5
115.3
148.5
149.3
110.9
128.3
C-3’/H-2’; C-3’/H-5’; C-3’/H-12
C-4’/H-2’; C-4’/H-6’; C-4’/H-13
C-5’/H-6’
with a JMS 2000 data system at 70 eV. Spectral data are consistent
with assigned structures. The molecular ion for compounds con-
taining chloro-group was calculated according to 35Cl isotope. Thin-
layer chromatography was carried out to monitor the reactions
using silica gel (Merck No. 5554). Dry solvents were used
throughout. Compounds 1–3 and 4–6 were synthesized according
to reported literature procedures [25].
–
7.49 (m, 1H)
7.49 (m, 1H)
C-6’/H-2’; C-6’/H-5’
activity by acetic acid-induced writhing method in mice, all
compounds exhibited moderate to good activity. These compounds
were also showed superior GI safety profile along with reduction in
lipid peroxidation as compared with ibuprofen.
5.1.1. General procedure for the synthesis of 6-chloromethyl-2-aryl-
1-benzopyran-4-one derivatives 7–9
Compounds 11 and 16 were most active against both bacterial
and fungal strains with MIC of 10
was active only against fungal strain with MIC of 10
m
g/mL. However, compound 19
2-Aryl-1-benzopyran-4-one derivatives (4–6) (0.01 mol) were
dissolved in acetic acid (80%; 75 mL) and paraformaldehyde
(0.04 mol; 1.2 g) was added. The solution was maintained at
90–95 ꢂC and hydrogen chloride gas passed until a shining crys-
talline product separated (1.5 h). The reaction mixture was cooled
when more products separated which was recrystallized from
dioxane to give TLC pure 6-chloromethyl-2-aryl-1-benzopyran-4-
one derivatives.
mg/mL.
Among the newer derivatives, two compounds 11 and 16
emerged as lead compounds. It is conceivable that these derivatives
could be further modified to develop potent and safer anti-
inflammatory and analgesic agents with an additional antimicro-
bial activity. Further studies to acquire more information about
quantitative structure–activity relationship (QSAR) are in progress
in our laboratory.
5. Experimental protocols
Table 4
Analgesic effects along with ulcerogenic and lipid peroxidation effect of some
6-substitutedmethyl-2-aryl-1-benzopyran-4-one derivatives.
5.1. Chemistry
Chemicals were purchased from Merck and Sigma–Aldrich as
‘synthesis grade’ and used without further purification. Melting
points (m.p.) were determined in open capillary tubes and are
given uncorrected. Elemental analyses were performed on a Per-
kin–Elmer analyzer and were in range of ꢃ0.4% for each element
analyzed (C, H, N). The IR spectra were measured as potassium
bromide pellets using a Perkin–Elmer 1725X spectrophotometer. 1H
NMR spectra were recorded on Bruker spectropsin DPX-300 MHz
in CDCl3 with tetramethylsilane (TMS) as an internal standard;
Compound Severity
indexa
Lipid peroxidationc Peripheral analgesic activity
(Writhing test) % protection
Control
Ibuprofen
0.00 ꢃ 0.00
0.241 ꢃ 0.007b,***
0.9 ꢃ 0.36* 0.607 ꢃ 0.008a,***
65.06 ꢃ 1.39
11
13
16
18
21
23
0.2 ꢃ 0.12
0.4 ꢃ 0.4
0.1 ꢃ 0.1
0.4 ꢃ 0.29
0.1 ꢃ 0.1
0.526 ꢃ 0.023a,b,*** 50.80 ꢃ 2.14***
0.599 ꢃ 0.008a,b,**
40.36 ꢃ 1.19***
0.331 ꢃ 0.006a,b,*** 53.61 ꢃ 0.92***
0.525 ꢃ 0.017a,b,*** 45.38 ꢃ 1.01***
0.352 ꢃ 0.014a,b,*** 54.81 ꢃ 0.92***
0.3 ꢃ 0.12* 0.403 ꢃ 0.005a,b,*** 48.39 ꢃ 1.05***
*p< 0.05; **p < 0.01; ***p < 0.001.
chemical shifts (d) are reported in parts per million (ppm) down-
a
Relative to their respective control and data were analyzed by one-way ANOVA
field from TMS. The splitting pattern abbreviations are as follows: s,
singlet; bs, broad singlet; d, doublet; dd, double doublet; t, triplet;
q, quartet; m, multiplet. Mass spectroscopic analyses for
compounds were performed on a JEOL JMS-D 300 instrument fitted
followed by Turkey test for n ¼ 6.
b
Relative to the standard (Ibuprofen) and data were analyzed by one-way ANOVA
followed by Turkey test for n ¼ 6.
c
Lipid peroxidation activity is expressed as nmoles of MDA/mg of protein.

S.M. Hasan et al. / European Journal of Medicinal Chemistry 44 (2009) 4896–4903
4901
13C NMR (CDCl3)
d 153.98 (C-2),133.32 (C-3),173.91 (C-4),106.7 (C-5),
Table 5
Antibacterial and antifungal study; MIC results of 7–24.
146.09 (C-6), 128.48 (C-7), 131.18 (C-8), 145.95 (C-9), 117.21 (C-10),
131.4 (C-1’), 128.1 (C-2’,6’), 128.6 (C-3’,5’), 131.57 (C-4’), 66.42 (CH2),
29.2 (CH3), 28.8 (CH3). MS: m/z 308(Mþ), 265. IR (cmꢀ1, KBr): 3062,
1692. Anal. Calcd. for C19H19NO3: C, 73.77; H, 6.19; N, 4.53. Found: C,
73.72; H, 6.17; N, 4.54.
Compounds Staphylococcus Escherichia coli Rhizopus oryza Penicillium
aureus
(ATCC-29737)
(ATCC-8739)
(NRRL-21498)
citrum
(NCIM-768)
Norfloxacin 6.25
Fluconazole
7
8
6.25
–
50
50
50
10
50
50
50
25
10
50
10
10
50
>100
>100
>100
50
–
6.25
10
10
10
10
50
50
10
10
10
25
25
10
>100
25
50
50
–
–
10
10
50
10
50
50
25
25
10
25
25
25
>100
50
>100
>100
50
6.25
>100
>100
50
5.1.2.2. 6-Morphilinomethyl-2-(4-methoxyphenyl)-1-benzopyran-4-
one (11). Yield: 48%, m.p.146 ꢂC. 1H NMR (CDCl3)
d 2.58 (t, 4H, H-3,5,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
10
morpholine ring), 3.45 (s, 2H, CH2), 3.72 (t, 4H, H-2,6, morpholine
ring), 3.92 (s, 3H, OCH3) 7.02 and 8.12 (d each, 2 ꢄ A2B2, p-
substituted phenyl), 7.3 (m, 2H, H-3,8, chromone ring), 7.66 (d, 1H,
H-7, chromone ring), 8.27 (d, 1H, H-5, chromone ring). MS: m/z
350(Mþ), 265. IR (cmꢀ1, KBr): 3060,1688. Anal. Calcd. for C21H21NO4:
C, 71.78; H, 6.02; N, 3.99. Found: C, 71.64; H, 6.04; N, 3.97.
>100
>100
25
50
10
25
50
10
>100
25
5.1.2.3. 2-(4-Methoxyphenyl)-6-(4-toluidinomethyl)-1-benzopyran-
4-one (12). Yield: 46%, m.p. 136 ꢂC. 1H NMR (CDCl3)
d 2.20 (s, 3H,
>100
50
25
CH3), 3.87 (s, 3H, OCH3) 4.03 (s, 2H, CH2), 6.42 and 6.87 (d, each,
2 ꢄ A2B2, p-disubstituted phenyl), 6.96 and 7.23 (d, each, 2 ꢄ A2B2,
phenyl), 7.32 (m, 2H, H-3,7, chromone ring), 7.64 (m, 1H, H-8,
chromone ring), 8.12 (d,1H, H-5, chromone ring). MS: m/z 370 (Mþ),
265. IR (cmꢀ1, KBr): 3192, 3050, 1672. Anal. Calcd. for C24H21NO3: C,
77.61; H, 5.70; N, 3.77. Found: C, 77.82; H, 5.67; N, 3.78.
>100
* MIC (
m
g/mL) ¼ minimum inhibitory concentration, i.e., the lowest concentration to
completely inhibit microbial growth.
5.1.1.1. 6-Chloromethyl-2-(4-methoxyphenyl)-1-benzopyran-4-one (7).
Yield: 46%, m.p.170 ꢂC. 1H NMR (CDCl3)
d
3.91 (s, 3H, OCH3), 4.63
5.1.2.4. 2-(4-Methoxyphenyl)-6-(4-piperazinomethyl)-1-benzopyran-
(s, 2H, CH2), 7.06 and 7.84 (d each, 2 ꢄ A2B2, p-substituted phenyl),
4-one (13). Yield: 50%, m.p. 140 ꢂC. 1H NMR (CDCl3)
d 2.37 (s, 4H, H-
7.42 (m, 2H, H-7,8, chromone ring), 7.69 (s,1H, H-3, chromone ring),
3,5, piperazine ring), 2.65 (s, 4H, H-2,6, piperazine ring), 3.49 (s, 2H,
CH2), 3.78 (s, 3H, OCH3), 6.92 and 7.39 (d, each, 2 ꢄ A2B2, phenyl),
7.62 (m, 1H, H-7, chromone ring), 7.72 (m, 1H, H-8, chromone ring),
7.78 (s, 1H, H-3, chromone ring), 8.14 (d, 1H, H-5, chromone ring),
9.28 (bs,1H, NH). MS: m/z 349 (MD), 265. IR (cmꢀ1, KBr): 3360, 3058,
1676. Anal. Calcd. for C21H22N2O3: C, 71.98; H, 6.33; N, 7.99. Found: C,
71.86; H, 6.34; N, 7.97.
8.28 (d, 1H, H-5, chromone ring). 13C NMR (CDCl3)
d 154.31 (C-2),
133.21 (C-3), 174.21 (C-4), 106.5 (C-5), 146.06 (C-6), 128.44 (C-7),
131.24 (C-8), 146.15 (C-9), 117.19 (C-10), 131.29 (C-1’), 127.4 (C-2’,6’),
128.1 (C-3’,5’), 131.27 (C-4’), 66.21 (CH2). MS: m/z 300(Mþ), 265. IR
(cmꢀ1, KBr): 3060, 1690. Anal. Calcd. for C17H13ClO3: C, 67.89; H,
4.36. Found: C, 67.68; H, 4.35.
5.1.1.2. 6-Chloromethyl-2-(3,4-dimethoxyphenyl)-1-benzopyran-4-one
5.1.2.5. 4-{4-Oxo-2-(4-methoxyphenyl)-6-benzopyranylmethylamino}-
(8). Yield: 52%, m.p. 171 ꢂC. 1H NMR (CDCl3)
d
3.99 (s, 6H, 2 ꢄ OCH3),
1-benzene-sulfonamide (14). Yield: 52%, m.p. 160 ꢂC. 1H NMR (CDCl3)
4.66 (s, 2H, CH2), 7.04 (s, 1H, H-3, chromone ring) 7.24 (d, 1H, H-2,
phenyl) 7.49 (m, 3H, H-5,6, phenyl & H-8, chromone ring), 7.70 (d, 1H,
H-7, chromone ring), 8.28 (d, 1H, H-5, chromone ring). MS: m/z
330(Mþ), 295. IR (cmꢀ1, KBr): 3058, 1692. Anal. Calcd. for C18H15ClO4:
C, 65.36; H, 4.57. Found: C, 65.52; H, 4.59.
d 3.91 (s, 3H, OCH3), 4.21 (s, 2H, CH2), 4.6 (s, 2H, NH2), 6.69 and 7.78 (d,
each, 2 ꢄ A2B2, p-disubstituted phenyl), 6.716 (m, 2H, H-3,8, chro-
mone ring), 7.06 and 7.42 (d, each, 2 ꢄ A2B2, phenyl), 7.62 (d, 1H, H-7,
chromone ring), 8.19 (d, 1H, H-5, chromone ring), 9.62 (bs, 1H, NH).
MS: m/z 436 (MD), 265. IR (cmꢀ1, KBr): 3220, 3190, 3100, 3068, 1680.
Anal. Calcd. for C23H20N2O5S: C, 63.29; H, 4.62; N, 6.42. Found: C,
63.38; H, 4.64; N, 6.41.
5.1.1.3. 6-Chloromethyl-2-(2-chlorophenyl)-1-benzopyran-4-one (9).
Yield: 38%, m.p. 178 ꢂC. 1H NMR (CDCl3)
d. 4.20 (s, 2H, CH2), 7.32
(t, 1H, H-4, phenyl), 7.52 (dd, 1H, H-6, phenyl), 7.72 (m, 3H, H-3,5,
phenyl & H-7, chromone ring), 7.84 (m, 1H, H-8, chromone ring),
8.10 (s, 1H, H-3, chromone ring), 8.18 (d, 1H, H-5, chromone ring),
MS: m/z 305(Mþ), 270. IR (cmꢀ1, KBr): 3072, 1698. Anal. Calcd. for
C16H10Cl2O2: C, 62.97; H, 3.30. Found: C, 62.78; H, 3.31.
5.1.2.6. 6-Dimethylaminomethyl-2-(3,4-dimethoxyphenyl)-1-benzo-
pyran-4-one (15). Yield: 42%, m.p. 166 ꢂC. 1H NMR (CDCl3)
d 2.61 (s,
6H, 2 ꢄ NCH3) 3.98 (s, 6H, 2 ꢄ OCH3), 5.34 (s, 2H, CH2), 7.03 (d, 1H, H-
5, phenyl), 7.44 (m, 4H, H-2,6, phenyl & H-3,7, chromone ring), 7.71
(m,1H, H-8, chromone ring), 8.22 (d,1H, H-5, chromone ring). MS: m/
z 338 (MD), 295. IR (cmꢀ1, KBr): 3064, 1696. Anal. Calcd. for
C20H20NO4: C, 70.78; H, 6.24; N, 4.13. Found: C, 70.82; H, 6.25; N, 4.14.
5.1.2. Generalprocedureforthesynthesisof6-aminomethyl-2-aryl-1-
benzopyran-4-one derivatives 10–24
The appropriate amines (0.04 mol) were added to solution of
compounds 7–9 (0.01 mol) in alcohol (75 mL) and the reaction
mixture was heated on a steam bath for 6 h. The residue obtained
on removal of alcohol was treated with dilute hydrochloric acid and
filtered. The filtrate was neutralized with sodium-bi-carbonate
solution and the product obtained was crystallized from alcohol.
5.1.2.7. 2-(3,4-Dimethoxyphenyl)-6-morphilinomethyl-1-benzopyran-
4-one (16). Yield: 54%, m.p. 156 ꢂC. 1H NMR (CDCl3)
d 2.61 (s, 4H, H-
2,6, morpholine ring), 3.47 (s, 2H, CH2), 3.70 (s, 4H, H-3,5, morpholine
ring), 3.97 (s, 6H, 2 ꢄ OCH3), 6.99 (d, 1H, H-5, phenyl), 7.41 (m, 2H, H-
2, phenyl & H-7, chromone ring), 7.65 (m, 2H, H-6, phenyl & H-8,
chromone ring), 7.92 (s, 1H, H-3, chromone ring), 8.23 (d, 1H, H-5,
chromone ring). MS: m/z 381 (MD), 295. IR (cmꢀ1, KBr): 3064, 1692.
Anal. Calcd. for C22H23NO5: C, 69.28; H, 6.08; N, 3.67. Found: C, 69.34;
H, 6.06; N, 3.65.
5.1.2.1. 6-Dimethylaminomethyl-2-(4-methoxyphenyl)-1-benzopyran-
4-one (10). Yield: 44%, m.p. 156 ꢂC. 1H NMR (CDCl3)
d 2.60 (s, 6H,
2 ꢄ NCH3), 3.87 (s, 3H, OCH3), 5.32 (s, 2H, CH2), 7.23 and 7.62 (d each,
2 ꢄ A2B2, p-substituted phenyl), 7.51 (m, 2H, H-3,7, chromone ring),
7.67 (m, 1H, H-8, chromone ring), 8.23 (d, 1H, H-5, chromone ring).
5.1.2.8. 2-(3,4-Dimethoxyphenyl)-6-(4-toluidinomethyl)-1-benzo-
pyran-4-one (17). Yield: 38%, m.p. 150 ꢂC. 1H NMR (CDCl3)
d 2.21 (s,

4902
S.M. Hasan et al. / European Journal of Medicinal Chemistry 44 (2009) 4896–4903
3H, CH3), 3.75 (s, 3H, OCH3), 3.96 (s, 3H, OCH3), 4.23 (s, 2H, CH2),
6.45 and 6.91 (d, each, 2 ꢄ A2B2, p-disubstituted phenyl), 6.98 (d,
1H, H-5, phenyl), 7.38 (m, 4H, H-2,6, phenyl & H-3,7, chromone
ring), 7.64 (m, 1H, H-8, chromone ring), 8.22 (d, 1H, H-5, chromone
ring), 9.48 (bs, 1H, NH). MS: m/z 401(MD), 372, 295. IR (cmꢀ1, KBr):
3196, 3056, 1680. Anal. Calcd. for C25H23NO4: C, 74.79; H, 5.77; N,
3.49. Found: C, 74.84; H, 5.74; N, 3.48.
5.1.2.15. 4-{4-oxo-2-(2-chlorophenyl)-6-benzopyr-
anylmethylamino}-1-benzene-sulfonamide (24). Yield: 48%, m.p.
172 ꢂC. 1H NMR (CDCl3)
d 4.12 (s, 2H, CH2), 6.72 (d, 2H, H-2,6, sul-
phanilamide ring), 6.84 (s,1H, H-3, chromone ring), 6.98 (s, 2H, NH2),
7.65 (m,5H, H-4, phenyl, H-3,5, sulphanilamide ring & NH), 7.82 (m,
3H, H-3,5,6, phenyl), 7.96 (m, 1H, H-7, chromone ring), 8.18 (d, 1H, H-
8, chromone ring). MS: m/z 440(MD), 441(M D 1), 270. IR (cmꢀ1
,
KBr): 3222, 3190, 3110, 3070, 1684. Anal. Calcd. for C22H17N2O4SCl: C,
59.93; H, 3.89; N, 6.35. Found: C, 59.82; H, 3.90; N, 6.34.
5.1.2.9. 2-(3,4-Dimethoxyphenyl)-6-(4-piperazinomethyl)-1-benzo-
pyran-4-one (18). Yield: 42%, m.p. 150 ꢂC. 1H NMR (CDCl3)
d 2.37 (s,
4H, H-3,5, piperazine ring), 2.65 (s, 4H, H-2,6, piperazine ring), 3.29 (s,
2H, CH2), 3.83 (s, 3H, OCH3), 3.85 (s, 3H, OCH3), 7.11 (d,1H, H-5, phenyl),
7.46 (m, 1H, H-2, phenyl), 7.65 (m, 2H, H-6, phenyl & H-7, chromone
ring), 7.78 (m, 1H, H-8, chromone ring), 8.02 (s, 1H, H-3, chromone
ring), 8.05 (d, 1H, H-5, chromone ring), 9.42 (bs, 1H, NH). MS: m/z
380(MD), 295. IR (cmꢀ1, KBr): 3364, 3062, 1678. Anal. Calcd. for
C22H24N2O4: C, 69.46; H, 6.36; N, 7.36. Found: C, 69.58; H, 6.34; N, 7.37.
5.2. Anti-inflammatory activity
The synthesized compounds were evaluated for their anti-
inflammatory activity using carrageenan-induced paw edema
method of Winter et al. [26]. The experiment was performed on
Albino rats of Wistar strain of either sex, weighing 180–200 g. The
animals were randomly divided into groups of six. Group I was kept
as control, and received only 0.5% carboxymethyl cellulose (CMC)
solution. Groups II was kept as standard and received ibuprofen
(20 mg/kg p.o.). Carrageenan solution (0.1% in sterile 0.9% NaCl
solution) in a volume of 0.1 mL was injected subcutaneously into
the sub-plantar region of the right hind paw of each rat, 30 min
after the administration of the test compounds and standard drugs.
The paw volume was measured by saline displacement shown on
screen of digital Plethysmometer (Ugo Basile) at 2 and 3 h after
carrageenan injection. Thus the edema volume in control group (Vc)
and edema volume in groups treated with test compounds (Vt)
were measured and the percentage inhibition of edema was
calculated using the formula:
5.1.2.10. 4-{4-Oxo-2-(3,4-dimethoxyphenyl)-6-benzopyr-
anylmethylamino}-1-benzene-sulfonamide (19). Yield: 46%, m.p.
178 ꢂC.1H NMR (CDCl3)
d 3.58 (s, 3H, OCH3), 3.81 (s, 3H, OCH3), 4.10 (s,
2H, CH2), 6.611 (d, 2H, H-2,6, sulphanilamide ring), 6.716 (s, 1H, H-3,
chromone ring), 6.960 (s, 2H, NH2), 7.13 (d, 1H, H-5, phenyl), 7.422
(m,5H, H-2, phenyl, H-3,5, sulphanilamide ring, H-5, chromone ring &
NH), 7.707 (d, 1H, H-6, phenyl), 7.841 (m, 1H, H-7, chromone ring),
8.09 (d, 1H, H-8, chromone ring). MS: m/z 466(MD), 295. IR (cmꢀ1
,
KBr): 3218, 3192, 3110, 3072, 1682. Anal. Calcd. for C24H22N2O6S: C,
61.79; H, 4.75; N, 6.00. Found: C, 61.88; H, 4.74; N, 6.01.
5.1.2.11. 2-(2-Chlorophenyl)-6-dimethylaminomethyl-1-benzopyran-
Anti-inflammatory activity (% inhibition) ¼ (Vc ꢀ Vt)/Vc ꢄ 100
4-one (20). Yield: 48%, m.p. 156 ꢂC. 1H NMR (CDCl3)
d 2.62 (s, 6H,
2 ꢄ NCH3), 5.42 (s, 2H, CH2), 7.31 (t, 1H, H-4, phenyl), 7.46 (dd, 1H,
H-6, phenyl), 7.59 (d, 2H, H-3,5, phenyl), 7.67 (m, 2H, H-3,7, chro-
mone ring), 7.82 (m, 1H, H-8, chromone ring), 8.28 (d, 1H, H-5,
chromone ring). MS: m/z 313(MD), 314(M D 1), 270. IR (cmꢀ1, KBr):
3062, 1694. Anal. Calcd. for C18H15NO2Cl: C, 68.90; H, 5.14; N, 4.46.
Found: C, 68.72; H, 5.16; N, 4.44.
5.3. Analgesic activity
Compounds which showed anti-inflammatory activity above
75% of ibuprofen were screened for analgesic activity. Analgesic
activity was done by acetic acid induce writhing method [27].
Swiss albino mice (25–30 g) of either sex were divided into
group of six in each. A 1% aqueous acetic acid solution (i.p. injection
in a volume of 0.1 mL) was used as writhing induced agent. Mice
were kept individually in the test cage, before acetic acid injection
and habituated for 30 min. Screening of analgesic activity was
performed after p.o. administration of test drugs at a dose of
20 mg/kg. Group I was taken as control and received CMC
suspension only, group II received reference drug ibuprofen and
rest of the groups were treated with test drugs (20 mg/kg) sus-
pended in 1.0% CMC orally. After 1 h of drug administration
0.10 mL of 1% acetic acid solution was given to mice intraperito-
neally. Stretching movements consisting of arching of the back,
elongation of body and extension of hind limbs were counted for
5–15 min of acetic acid injection. The analgesic activity was
expressed in terms of percentage inhibition.
5.1.2.12. 2-(2-Chlorophenyl)-6-morphilinomethyl-1-benzopyran-4-
one (21). Yield: 52%, m.p. 148 ꢂC. 1H NMR (CDCl3)
d 2.60 (s, 4H, H-
2,6, morpholine ring), 3.72 (s, 4H, H-3,5, morpholine ring), 3.82 (s,
2H, CH2), 7.41 (m, 3H, H-3,4, phenyl & H-7, chromone ring), 7.65 (m,
4H, H-5,6, phenyl & H-3,8, chromone ring), 8.08 (d, 1H, H-5, chro-
mone ring). MS: m/z 355(MD), 356(M D 1), 270. IR (cmꢀ1, KBr):
3058, 1690. Anal. Calcd. for C20H18NO3Cl: C, 67.51; H, 5.10; N, 3.94.
Found: C, 67.58; H, 5.13; N, 3.96.
5.1.2.13. 2-(2-Chlorophenyl)-6-(4-toluidinomethyl)-1-benzopyran-4-
one (22). Yield: 50%, m.p. 162 ꢂC. 1H NMR (CDCl3)
d 2.48 (s, 3H, CH3),
4.38 (s, 2H, CH2), 6.74 and 6.86 (d, each, 2 ꢄ A2B2, p-disubstituted
phenyl), 7.33 (t,1H, H-4, phenyl), 7.46(dd,1H, H-6, phenyl), 7.62(d, 2H,
H-3,5, phenyl), 7.64 (m, 3H, H-3,7,8, chromone ring), 8.14 (d, 1H, H-5,
chromone ring), 9.64 (bs,1H, NH). MS: m/z 375(MD), 376(M D 1), 270.
IR (cmꢀ1, KBr): 3190, 3048, 1676. Anal. Calcd. for C23H18NO2Cl: C,
73.50; H, 4.83; N, 3.73. Found: C, 73.62; H, 4.85; N, 3.71.
%Analgesic
activity ¼ {(n ꢀ n0)/n} ꢄ 100where,
n ¼ mean
number of writhes of control group, n0 ¼ mean number of writhes
of test group.
5.4. Acute ulcerogenesis
5.1.2.14. 2-(2-Chlorophenyl)-6-(4-piperazinomethyl)-1-benzopyran-
4-one (23). Yield: 54%, m.p. 142 ꢂC. 1H NMR (CDCl3)
d
2.58 (s, 4H, H-
Acute ulcerogenesis test was done according to Cioli et al. [28].
Albino rats (150–200 g) were divided into different groups con-
sisting of six animals in each group. Ulcerogenic activity evaluated
after p.o. administration of test compounds or ibuprofen at the dose
of 60 mg/kg. Control rats received p.o. administration of vehicle
(suspension of 1% methyl cellulose). Food but not water was
removed 24 h before administration of the test compounds. After
the drug treatment the rats were fed with normal diet for 17 h and
3,5, piperazine ring), 2.75 (s, 4H, H-2,6, piperazine ring), 4.22 (s, 2H,
CH2), 7.34 (t,1H, H-4, phenyl), 7.49 (dd,1H, H-6, phenyl), 7.68 (m, 3H,
H-3,5, phenyl & H-7, chromone ring), 7.82 (m, 1H, H-8, chromone
ring), 8.02 (s, 1H, H-3, chromone ring), 8.14 (d, 1H, H-5, chromone
ring), 9.82 (bs, 1H, NH). MS: m/z 354(MD), 355(M D 1), 270. IR
(cmꢀ1, KBr): 3358, 3060, 1680. Anal. Calcd. for C20H19N2O2Cl: C,
67.70; H, 5.40; N, 7.89. Found: C, 67.86; H, 5.41; N, 7.87.

S.M. Hasan et al. / European Journal of Medicinal Chemistry 44 (2009) 4896–4903
4903
then sacrificed. The stomach was removed and opened along the
Acknowledgement
greater curvature, washed with distilled water and cleaned gently
by dipping in normal saline. The mucosal damage was examined by
means of a magnifying glass. For each stomach the mucosal damage
was assessed according to the following scoring system: 0.5:
redness, 1.0: spot ulcers, 1.5: hemorrhagic streaks, 2.0: ulcers > 3
but < 5, 3.0: ulcers > 5. The mean score of each treated group minus
the mean score of control group was regarded as severity index of
gastric mucosal damage.
The authors are thankful to Prof. M.S.Y. Khan for valuable
suggestions. Thanks are also due to Dr. (Mrs.) Shaukat Shah, In-
charge animal house, Jamia Hamdard, New Delhi, for providing
animals for pharmacological studies.
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6. Statistical analysis
Data were expressed as the mean ꢃ standard error (S.E.) of the
means. For a statistical analysis of the data, group means were
compared by one-way analysis of variance (ANOVA) with post hoc
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