Design, synthesis and evaluation of chalcone derivatives as anti- Inflammatory, antioxidant and antiulcer agents

Article abstract of DOI:10.2174/157018012800389368

In the present study, a series of chalcone derivatives were designed based on QSAR analysis. The designed compounds were synthesized by Claisen Schmidt condensation and evaluated for anti-inflammatory, antioxidant and antiulcer activities. The results of

Full text of DOI:10.2174/157018012800389368

Letters in Drug Design & Discovery, 2012, 9, 479-488
479
Design, Synthesis and Evaluation of Chalcone Derivatives as Anti-
Inflammatory, Antioxidant and Antiulcer Agents
Alka N. Choudhary*, Arun Kumar and Vijay Juyal
Medicinal Chemistry Research Laboratory, Department of Pharmaceutical Sciences, Bhimtal campus, Kumaun
University, Bhimtal-263136, Nainital, Uttarakhand, India
Received January 24, 2012: Revised February 14, 2012: Accepted February 22, 2012
Abstract: In the present study, a series of chalcone derivatives were designed based on QSAR analysis. The designed
compounds were synthesized by Claisen Schmidt condensation and evaluated for anti-inflammatory, antioxidant and
antiulcer activities. The results of the best 2D & 3D QSAR models suggested that by introducing electron releasing groups
at R2 and introducing heteroatom with increasing bulkiness at R4 in the benzylideneacetophenone nucleus will increase
the activity. The structures of the compounds were established by IR, 1H NMR and mass spectral analysis. All the
compounds were evaluated for their anti-inflammatory (carrageenan-induced rat paw edema assay), antioxidant
(inhibition of lipid peroxidation) and antiulcer activity (indomethacin-induced gastric damage). Of 10 compounds
screened, compounds 1e and 1d exhibited promising anti-inflammatory activity with 68-70% inhibition at 100mg/kg ,
inhibition of lipid peroxidation with IC50 2.47 & 3.1 µg/ml respectively. The Compounds 1e, 1j and 1d exhibited good
gastro protective action as indicated by their low ulcer score. Overall, 1e was obtained as lead compound with promising
anti-inflammatory, antioxidant and antiulcer activities.
Keywords: Antioxidants, Antiulcer, Chalcones, Inflammation, Rheumatoid Arthritis, NSAIDs.
1. INTRODUCTION
polyhydroxylated in the aryl rings. The radical quenching
properties of the phenolic groups present in many chalcones
have raised interest in using the compounds [14-15]. The aim
of the present study is to design, synthesize & evaluate
chalcone derivatives based on best QSAR model. A
Quantitative structure–activity relationship (QSAR) enables
the investigators to establish a reliable quantitative structure–
activity and structure–property relationships to derive QSAR
model [16] to predict the activity of novel molecules prior to
their synthesis.
Non-steroidal anti-inflammatory drugs (NSAIDs) still
remain among the most extensively used drugs world wide
and have been used in the treatment of inflammatory
conditions like rheumatoid arthritis, osteoarthritis,
orthopedic injuries, postoperative pain, etc [1-2]. However,
the use of conventional NSAIDs has been restricted due to
their side effects especially gastric erosion and ulcers [3-5].
Thus, there is an urgent need for new targets that are
required for the design and development of novel anti-
inflammatory agents as an alternative to NSAIDs. Reactive
-
oxygen species (ROS) in the form of super oxide anion (O2
2. EXPERIMENTAL
2.1. QSAR Analysis
.), hydroxyl radical (OH.) and hydrogen peroxide attack
various biological macromolecules (proteins, enzyme, DNA,
etc) under ‘oxidative stress’ conditions, giving rise to a
number of inflammatory, metabolic disorders, cellular aging,
reperfusion damage and cancer [6-7]. Interestingly a number
of therapeutically useful NSAIDS have been shown to act by
virtue of their free radical scavenging activity [8-10].
Antioxidants are the compounds that prevent oxidative
damage induced by free radicals and reactive oxygen
species. Thus, antioxidant therapy has also gained immense
importance in the treatment of above-mentioned diseases
[11].
Nineteen compounds belonging to chalcone derivatives
were taken from literature [17] (Table 1). All the biological
activity data had been converted to negative logarithmic
mole dose (pIC50) for QSAR analysis. The correlations were
sought between inhibitory activity and various substituents
constants at position R1, R2, R3& R4 of molecule and indicator
variable for the presence of methoxy at R5 (IV1) and presence
of hydroxy group in the ring system at R6 position (IV2).
The value of substituent constants like hydrophobic (π),
steric (molar refractivity MR), hydrogen acceptor (HA), and
hydrogen donor (HD) and electronic (field effect F,
resonance effect or R) and Hammett’s constant (σ) were
taken from literature for position R1, R2, R3 & R4. The series
was also subjected to Molecular Modeling studies and
Quantum mechanical calculations were performed using CS
Chem. Office version 10.0 (Cambridge soften ware) running
on a P-IV processor [18]. All molecules were built using
Chemdraw Ultra ver 10.0 and subjected to energy
minimization using Allinger’s MM2 force field. The
minimization is continued until the root mean square (RMS)
gradient value reaches a value smaller than 0.1 kcal/molAº.
Chalcones, or 1,3 –diaryl-2-propen-1-ones, belong to the
flavanoid family [12]. Chemically they consist of open-chain
flavanoids in which the two aromatic rings are joined by a
three-carbon α, β unsaturated carbonyl system [13]. A vast
number
of
naturally
occurring
chalcones
are
*Address correspondence to this author at the Medicinal Chemistry
Research Laboratory, Department of Pharmaceutical Sciences, Bhimtal
campus, Kumaun University, Bhimtal-263136, Nainital, Uttarakhand, India;
Tel: +919411313837; Fax: 05942-248307;
E-mail: alka_pharma@rediffmail.com
1875-628X/12 $58.00+.00
© 2012 Bentham Science Publishers

480 Letters in Drug Design & Discovery, 2012, Vol. 9, No. 5
Choudhary et al.
Table 1. Chalcone Derivatives and their Biological Activities
R3
R2
R4
R5
R1
O
R6
No
R1
R2
R3
R4
R5
R6
pIC50(BA2)
1
2
CH3O
CH3O
CH3O
CH3O
CH3O
CH3O
CH3O
CH3O
CH3O
CH3O
t-Bu
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
H
H
H
CH3
CH3O
Cl
H
H
H
H
H
H
OH
H
H
H
H
H
H
H
H
H
H
H
H
H
H
-1.25
-1.09
-1.26
-0.85
-1.17
-0.107
-0.704
-1.35
-1.31
-0.62
-0.55
-0.29
-1.29
-0.70
-0.55
-0.26
-0.29
-0.22
-0.26
3
H
H
4
H
H
5
H
H
H
6
CH3O
CH3O
H
CH3
CH3O
OH
F
H
7
H
8
CH3O
H
9
H
10
11
12
13
14
15
16
17
18
19
CH3O
t-Bu
t-Bu
H
F
H
F
H
t-Bu
OH
OH
F
CH3O
H
CH3O
i-Pr
i-Pr
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
H
t-Bu
CH3
C2H5O
CH3O
OH
Cl
H
t-Bu
H
t-Bu
H
t-Bu
H
t-Bu
H
The Hamiltonian approximations Austin model -1(AM-1)
method and RHF (restricted Hartee-Fork:closed shell) wave
function was adopted for reoptimization until the root mean
square (RMS) gradient attains a value smaller than 0.001
kcal/molAº by the use of GAMESS module. Different
combinations of descriptors were subjected to sequential
regression analysis employing VALSTAT software [19]. In
stepwise multiple linear regression analysis [20] the
independent variables are individually added or deleted from
the model at each step of the regression depending on the
Fischer ratio values selected to enter and to remove until the
‘best’ model is obtained.
solution (1g in 10ml H2O) was added drop wise to the
reaction mixture on vigorous stirring for 30 minutes when
solution became turbid. The reaction temperature was
maintained between 20-25˚ C using a cold water bath on the
magnetic stirrer. After vigorous stirring for 4-5 hours the
reaction mixture was neutralized by 0.1-0.2N HCl whereby
the precipitation occurred. On filtering off, the crude
chalcones were dried in air and recrystallized by rectified
spirit [21]] (Scheme 1).
The melting points were recorded in open capillaries with
electrical melting point apparatus and were uncorrected. IR
spectra (nujol) were recorded using Perkin-Elmer FTIR-RX1
spectrophotometer. A 1HNMR spectrum was recorded on
Bruker Avance (400 MHz) spectrometer in DMSO solutions,
with tetra methyl silane (TMS) as internal standard. Mass
spectra were recorded on a Waters Q-T of micro MS. All the
reagents and solvents used were of analytical grade and were
used as supplied unless otherwise stated. Progress of the
reactions was monitored using TLC, performed on
aluminium plates precoated with silica gel-G, using
chloroform: methanol (9:1) as the solvent systems and the
spots were visualized by exposure to iodine vapors.
2.2. Synthesis & Characterization of Designed Comp-
ounds
The designed compounds, having higher predicted pIC50
value than observed pIC50 value, were synthesized.
a. General Method of Preparation of Chalcones
A mixture of benzaldehyde derivatives (0.01 mol) and
acetophenone derivatives (0.01 mol) was dissolved in 10 ml
rectified spirit in a 250 ml round-bottomed flask equipped
with a magnetic stirrer. Then 10 ml sodium hydroxide

Design, Synthesis and Evaluation of Chalcone Derivatives
Letters in Drug Design & Discovery, 2012, Vol. 9, No. 5 481
R3
R4
R5
R3
R4
R2
R1
C2H5OH
R2
+
H3C
NaOH
rt
CH
C
O
CH
C
R5
R6
R1
CHO
R6
O
Scheme 1. Synthesis of Chalcone derivatives.
2.3. Pharmacological Evaluation
absorbance of test compound. IC50 values (concentration of
sample required to scavenge 50% of free radicals) were
calculated from the regression equation, prepared from the
concentration of the samples and % inhibition of free radical
formation
All the experiments were carried out using Wistar rats of
either sex produced from IVRI, Bareilly, U.P. India. The
animals were housed, 12 hr. light and 12 hr. dark cycle in the
departmental animal house with free access to water and
standard diet. All experiments were performed as per the
norms of the ethical committee and the studies were
approved and clearance obtained by the ‘Institutional Review
Board’.
c. Antiulcer Activity
Anti-ulcer activity was measured using indomethacin
induced gastric ulcer model [24]. The animals were starved
for 24 h, groups of 6 rats of both sexes (pregnant females
excluded) were given a dose of 100 mg/kg, i.p. of test
compounds 30 min prior to indomethacin administration
(48mg/kg). Four hours later, animals were sacrificed by
cervical dislocation and stomach quickly removed, open out
along the greater curvature, carefully cleaned out with a
gentle stream of running distilled water and ulcers formed on
the granular mucosa were counted. The percentage of
inhibition of ulcers calculated using the formula.
a. Anti-Inflammatory Activity
Anti-inflammatory activity was measured using
carrageenan-induced rat paw edema assay [22]. Groups of 6
rats of both sexes (pregnant females excluded) were given a
three doses (25, 50,100 mg/kg, i.p.) of a test compound.
After 1h, 0.1 mL of 1% carrageenan suspension in 0.9%
NaCl solution was injected into sub planer tissue of the right
hind paw. The linear paw circumference was measured at 3rd
and 4th hours. The mean paw edema value for the test group
was compared with mean value for the control group. Anti-
inflammatory activity was measured as the percentage of
reduction in edema level when drug was present, relative to
control. Indomethacin (10mg/kg, i.p.) was administered as
reference drug whereas 10% Tween 80 was used as negative
control.
% inhibition of ulcers= C-T/C X 100
2.4. Statistical Analysis
The results were subjected to statistical analysis by using
Student’s t-test comparing the control with treated group.
Statistical significance was considered at p<0.05. The result
values were expressed as mean ± S.E.M (standard error of
mean).
b. Determination of the Inhibition of Lipid Peroxidation
Rat liver was used as the source of polyunsaturated fatty
acids for determining the extent of lipid per oxidation [23].
Liver was collected immediately after sacrificing animals by
cervical dislocation under ether anesthesia. The liver was
homogenized with 40mM Tris-HCl buffer (pH7) and
centrifuged at 3000 rpm for 10 min to get a clear
supernatant. Reaction mixture (4ml) containing 0.5 ml of
supernatant (liver), 3.2 ml of synthesized chalcones (1a-1o)
in different concentrations (0.1-25.6µg/ml and 100µL of
each of 0.15 M KCl ,15mM FeSO4 and 6mM ascorbic acid
was incubated at 37˚C for 1hr.Trichloroacetic acid
(TCA)(1ml,10%) was added to the reaction mixture and the
sample was centrifuged at 3000 rpm for 20 min at 4˚C to
remove insoluble proteins. Supernatant (1ml) was removed
and 1ml Thiobarbituric acid (TBA) (0.8%) was added to this
fraction followed by heating at 90˚C for 20 min in a water
bath. After cooling the colored TBA-MDA complex
extracted with organic solvent (2ml butanol), absorbance
was measured at 532 nm. All the assays were carried out in
duplicate. Percentage inhibition was calculated using the
formula.
3. RESULTS AND DISCUSSION
3.1. QSAR Analysis
The data set was subjected to stepwise multiple linear
regression analysis, in order to develop 2D-QSAR between
inhibitory activities as dependent variables and substituent
constants as independent variable, The statistically
significant equation [Eqn.1] with coefficient of correlation (r
= 0.946) was obtained.
BA = 0.354(±0.473) R2 + 1.256(±0.073) MR4 -1.023(±0.543)
σp2- 3.865
n=19, r = 0.946, r2 = 0.894, SE = 0.159, F = 40.365 (Eqn. 1)
The model indicates that steric i.e., molar refractivity
(MR) at R4 contributed positively, while on R2 position in
parent moiety, electronic effect (R) contributed positively
and Hammet constant (σp) contributed negatively to QSAR
model. The study suggested that bulkier substitution at R4 is
favorable for the lipid peroxidation inhibitory action and
introduction of electron releasing groups at R2 position may
prove to be helpful in development of more potent inhibitors.
% inhibition =[(Acontrol – Asample)/ Acontrol] X100.
Where, Acontrol is absorbance of the control reaction
(containing all regents except test compounds) and Asample is
The correlation between different physicochemical and
topological descriptors as independent variable and

482 Letters in Drug Design & Discovery, 2012, Vol. 9, No. 5
Choudhary et al.
Table 2. Descriptors (3D) Contributing to the Lipid Peroxidation Inhibitory Activity
No
SD
MTI
CAA
CC
TOE
Ov
1
2
68
70
76
69
74
78
84
82
76
84
84
90
74
80
78
86
84
82
77
514.41
690.49
879.14
702.69
661.45
904.60
1107.5
971.00
711.00
907.99
1634.6
1672.6
608.12
1288.2
1645.0
1912.3
1783.0
1632.4
1728.2
249.69
269.83
277.73
264.42
256.38
294.95
303.77
281.91
255.14
279.47
350.02
379.44
257.44
327.4
19
20
21
20
20
22
23
22
20
22
26
28
20
24
26
28
27
26
26
-16.6644
-12.7252
-11.8878
-16.6644
-10.4083
-19.3784
-13.7152
-12.8624
-11.7541
-18.6602
-11.55
1.486
1.505
1.517
1.504
1.468
1.548
1.554
1.493
1.482
1.53
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
1.529
1.57
-13.7209
-16.6643
-17.3392
-12.86
1.497
1.549
1.551
1.585
1.562
1.535
1.542
364.60
391.73
372.63
353.96
360.61
-11.6174
-12.1718
-11.9929
-12.1419
inhibitory data as dependent variable was established via
molecular modeling using 3D-QSAR. Statistical processing
by stepwise regression method gave many QSAR equations.
Only those parameters having intercorrelation below 0.6 and
confidence interval limit >95% were considered to select the
best model. The descriptors found in the best 3D QSAR
equations of chalcone derivatives are summarized in Table 2.
n=19, r=0.907, r2=0.822, variance=0.034, SEE=0.191,
F=23.202 (Eqn. 2)
BA2= 1.567(± 0.538) CC + 0.220(± 0.088) TOE + 0.012(±
0.0006)Ov -5.265
n=19, r=0.905, r2=0.819, variance=0.037, SEE=0.202,
F=20.924
(Eqn. 3)
The best equations along with its statistical measures are
given below.
Eqns. 2 & 3 having nearly same variance i.e., 82% but
eqn 2 having intercorrelation among the physicochemical
descriptors is less than eqn 3 which is desired for robustness
of the regression expression (Table 3 & 4). The overall high
BA2 = 0.189(± 0.066) SD + 0.226(± 0.085) MTI + 0.001(±
0.0003) CAA -4.838
Table 3. Correlation Matrix for Equation-2
SD
MTI
CAA
SD
1.000
0.140
0.237
MTI
CAA
1.000
0.067
1.0000
Table 4. Correlation Matrix for Equation-3
CC
TOE
Ov
CC
TOE
Ov
1.000
0.238
0.669
1.000
0.486
1.000

Design, Synthesis and Evaluation of Chalcone Derivatives
Letters in Drug Design & Discovery, 2012, Vol. 9, No. 5 483
Table 5. General Structure of Designed Compounds
R3
R2
R1
R4
R5
O
R6
R1=R3=R5=R6=H
S.No
R2
R4
Predicted pIC50 (µM)
1
2
N(CH3)2
N(CH3)2
N(CH3)2
N(CH3)2
N(CH3)2
N(CH3)2
OC2H5
OC2H5
OC2H5
OC2H5
OC2H5
OC2H5
OCH3
OH
Cl
Br
I
1.680
2.160
1.833
2.278
2.949
0.686
1.506
1.854
1.851
2.011
2.236
0.663
0.395
0.463
0.569
0.520
0.718
0.567
3
4
OCH3
OC2H5
NH2
Cl
5
6
7
8
Br
9
I
10
11
12
13
14
15
16
17
18
OCH3
OC2H5
NH2
NH2
Cl
OH
Br
OH
I
OH
OC2H5
NH2
OH
value r-value (0.907) and low standard error of estimate
prove (Eqn 2) to be the best model describing the activity.
QSAR analyses, following compounds were designed and
their activities were predicted with the help of best equations
(Table 5).
The study revealed that topological descriptors i.e.,
molecular topological index (MTI), sum of valence degree
(SD), steric descriptor i.e., connolly’s solvent accessible area
(CAA) parameters play a significant role in the model to
explain the variance in activity. Molecular topological index
contributed positively to the model, which suggests that
increased activity can be achieved by introduction of the
heteroatom and flexibility of substituent side chain, also
supported by the positive contribution of sum of valence
degree (SD) that illustrates that presence of heteroatom is
favorable for the activity [25-26]. Connolly’s accessible area,
steric descriptors [27]. The descriptors bears positive
coefficient in this equation, suggesting increase in the
bulkiness of the substituents is favorable for the activity, also
suggested by the 2D QSAR studies that steric effect is much
important on R4 position of the parent structure so increase
of bulkiness at R4 position may prove to be helpful in
development of more potent inhibitors.
3.2. Synthesis
Derivatives
&
Characterization of Chalcone
The designed compounds, having higher predicted pIC50
value than observed pIC50 value, were synthesized. The
synthesis was based on Claisen Schmidt reaction, which is
condensation reaction of substituted benzaldehyde with
substituted acetophenones in the presence of sodium
hydroxide and ethanol. The products were characterized by
comparison of their spectral and physical data with those of
authentic samples (Table 6 & 7).
3.3. Biological Evaluation
a. Anti-Inflammatory Activity
All the synthesized compounds were evaluated for anti-
inflammatory activity by carrageenan-induced rat paw
edema assay. The basis for the determination of anti-
inflammatory activity at third and fourth hour is that with
carrageen –induced rat paw model peak inflammatory
From the results of 2D and 3D QSAR analysis, it is
concluded that by introducing electron releasing groups at R2
and introducing heteroatom with increasing bulkiness at R4
will increase the activity. Based on inference of 2D & 3D

484 Letters in Drug Design & Discovery, 2012, Vol. 9, No. 5
Choudhary et al.
Table 6. The Chemical Profile of the Synthesized Compounds
Code
R2
R4
Molecular Formula
M.Wt
Yield %
Rf
mp(˚C)
1a
1b
1c
1d
1e
1f
N(CH3)2
N(CH3)2
N(CH3)2
N(CH3)2
N(CH3)2
OC2H5
Cl
Br
C17H16ClNO
C17H16BrNO
C17H16INO
C18H19NO2
C19H21NO2
C17H15ClO2
C17H15BrO2
C17H15IO2
C18H18O3
285.092
329.219
377.211
281.141
295.370
286.076
330.025
378.204
282.125
296.141
58
55
53
18
16
74
72
72
68
67
0.45
0.41
0.39
0.52
0.51
0.61
0.58
0.54
0.74
0.71
190-192
220-222
221-223
195-197
207-209
182-184
212-215
210-213
186-188
195-198
I
OCH3
OC2H5
Cl
1g
1h
1i
OC2H5
Br
OC2H5
I
OC2H5
OCH3
OC2H5
1j
OC2H5
C19H20O3
Table 7. IR, 1HNMR and Mass Spectral Data of Synthesized Compounds
No.
IR(cm-1)
NMR (δ ppm)
Mass (ESI)
3'
3''
R2
R4
4''
5''
2''
2'
4'
5'
2
1
3
6''
6'
O
1a
1b
1647(>C=O in conjugation with C=C),
1590,1552 (>C=C< in conjugation with
C=O), 1527,1460 (C=C aromatic
stretching), 725, 1227
7.86(dd, J=8Hz, J=16Hz 2H, Ar 2'H 6'H), 7.76(d,
J=16Hz, 1H3, =CH), 7.51 (d, J=12Hz 2H, Ar 2",6"-H),
7.42(d, J=8Hz, 2H, Ar 3', 5'H), 7.25(d, J=16Hz,
1H2,=CH), 6.66 (dd, J=8Hz, J= 12HZ, 2H, Ar 3", 5"-
H), 3.04(s,6H,-N(CH3)2)
m/z(relative intensity%):
286[M+1]+(54)
(C-Cl & C-N stretching)
1647(>C=O in conjugation with
C=C),1588,1551 (>C=C< in conjugation
with C=O), 1528,1460
(C=C aromatic stretching), 665,1226
(C-Br & C-N stretching)
7.85 (dd, J=8Hz, J=4Hz, 2H, Ar 2',6'H), 7.77(d, J=12Hz, m/z(relative intensity%):
1H3, =CH), 7.60(dd, J= 8Hz, J=4Hz, 2H, Ar 3', 5'H),
7.52 (d, J=8Hz, 2H, Ar 2",6"-H),7.24(d, J=16Hz, 1H2,
=CH), 6.67 (d, J=8Hz, 2H, Ar 3", 5"- H), 3.04(s,6H,-
N(CH3)2
352[M+Na]+(74),
330[M+1]+ (20)
7.82 (d, J=12Hz, 2H, Ar 2',6'H), 7.71 (d, J=16Hz, 1H3,
m/z(relative intensity%):
1c
1648 (>C=O in conjugation with C=C),
1576,1534(>C=C< in conjugation with
=CH), 7.66(d, J=8Hz, 2H, Ar 3', 5'H), 7.54 (d, J=12Hz,
378[M+1]+ (86)
C=O), 1508,1449(C=C aromatic stretching), 2H, Ar 2",6"-H), 7.30(d,J=16Hz, 1H2,=CH), 6.69
565,1218(C-I & C-N stretching)
(d,J=8Hz, 2H, Ar 3", 5"- H) 3.06(s,6H,-N(CH3)2)
7.86 (dd, J=4Hz, J=4Hz, J=4Hz, 2H, Ar 2',6'H), 7.80(d,
J=16Hz, 1H3, =CH), 7.61(dd, J=4Hz, J=8Hz, 2H, Ar 3',
5'H), 7.58 (d, J=4Hz,2H,Ar2",6"H),7.36(d,
m/z(relative intensity%):
1d
1642 (>C=O in conjugation with C=C),
1567,1556 (>C=C< in conjugation with
C=O), 1529,1457
304[281+Na]+(100)
(C=C aromatic stretching), 1257& 1064 (C-
J=16Hz,1H2,=CH), 6.93 (dd, J=4Hz, J=8Hz, 2H, Ar 3",
O asymmetric & symmetric stretching)
5"- H),3.84(s,3H,-OCH3), 3.04(s,6H,-N(CH3)2
1e
1f
1640 (>C=O in conjugation with C=C),
1584,1566 (>C=C< in conjugation with
C=O) 1510,1461(C=C aromatic stretching)
1267 & 1070 (C-O asymmetric &
symmetric stretching)
7.85 (dd, J=4Hz, J=8Hz,2H, Ar 2',6'H),7.76(d, J=16Hz,
1H3, =CH), 7.61(dd, J=4Hz, J=8Hz, 2H, Ar 3', 5'H),
7.57 (d, J=8Hz, 2H, Ar 2",6"-H), 7.36(d, J=16Hz,
1H2,=CH), 6.90 (d, J=8Hz, 2H, Ar 3", 5"- H), 1.41-
1.45(t, 3H, -CH3), 4.05-4.10 (q, 2H, -CH2), 3.06(s,6H,-
N(CH3)2)
m/z(relative intensity%):
296[M+1]+ (100)
318 [295 +Na]+ (82)
1658 (>C=O in conjugation with
C=C),1602(>C=C< in conjugation with
C=O), 1510,1459(C=C aromatic
stretching),721(C-Cl stretching), 1269 &
1036 (C-O asymmetric & symmetric
stretching)
7.93 (dd, J=4Hz, J=8Hz, 2H, Ar 2',6'H), 7.75(d, J=16Hz, m/z(relative intensity%): 287[M+1]+
1H3, =CH), 7.56 (d, J=4Hz, 2H, Ar 2",6"-H),7.43(dd,
(65)
J=4Hz, J=8Hz 2H, Ar 3', 5'H), 7.36(d,
J=16Hz,1H2,=CH), 6.89 (dd, J=4Hz, J=8Hz 2H, Ar 3",
5"- H),1.40-1.44(t, 3H, -CH3), 4.03-4.08 (q, 2H, -CH2)
7.85 (dd, J=4Hz, J=8Hz,2H, Ar 2',6'H),7.76(d, J=16Hz,
1H3, =CH), 7.61(dd, J=4Hz, J=8Hz, 2H, Ar 3', 5'H),
7.57 (d, J=8Hz, 2H, Ar 2",6"-H), 7.36(d, J=16Hz,
1H2,=CH), 6.90 (d, J=8Hz, 2H, Ar 3", 5"- H), 1.41-
1.45(t, 3H, -CH3), 4.05-4.10 (q, 2H, -CH2)
m/z(relative intensity%):
1g
1657 (>C=O in conjugation with C=C),
1584,1566(>C=C< in conjugation with
C=O), 665(C-Br stretching), 1267 & 1070
(C-O asymmetric & symmetric stretching)
1510,1461 (C=C aromatic stretching)
331[M+1]+(24)

Design, Synthesis and Evaluation of Chalcone Derivatives
Letters in Drug Design & Discovery, 2012, Vol. 9, No. 5 485
(Table 7). Contd…..
7.88 (d,J=8Hz, 2H, Ar 2',6'H), 7.77 (d, J=8Hz, 2H, Ar
m/z(relative intensity%):
1h
1653 (>C=O in conjugation with C=C),
1591,1459 (>C=C< in conjugation with
C=O,
C=C aromatic stretching), 1254 & 1026 (C-
O asymmetric & symmetric stretching), 461
(C-I stretching)
2",6"-H), 7.71(d, J=12Hz, 1H3, =CH),7.64(d, 2H, Ar 3',
5'H), 7.45(d, J=16Hz, 1H2,=CH), 6.91 (d,J=12Hz, 2H,
Ar 3", 5"- H), 1.42-1.46(t, 3H, -CH3), 4.03-4.08 (q, 2H,
CH2)
379[M+1] + (41)
1i
1654(>C=O in conjugation with C=C),
1596,1571(>C=C< in conjugation with
8.00 (dd, J=4Hz, J=8Hz, 2H, Ar 2',6'H), 7.74 (d,
J=16Hz, 1H3, =CH), 7.56 (d, J=8Hz, 2H, Ar 2",6"-H),
m/z(relative intensity%):
305[M+Na]+(100), 283[M+1]+(17)
C=O), 1507,1461(C=C aromatic stretching), 7.39(d, J=16Hz,1H2, =CH), 6.94 (dd,J=4Hz, J=8Hz, 2H,
1256 & 1075 (C-O asymmetric &
symmetric stretching)
Ar 3', 5'H), 6.89 (d, J=4Hz, 2H, Ar3" 5"- H), 1.40-
1.43(t, 3H, -CH3), 4.02-4.07 (q, 2H, -CH2); 3.85(s,3H,-
OCH3)
8.00 (dd, J=4Hz, J=8Hz, 2H, Ar 2',6'H), 7.75(d, J=
12Hz, 1H3, =CH), 7.59 (d, 2H, Ar 2",6"-H), 7.40(d,
J=16Hz, 1H2,=CH), 6.93 (d, J= 4Hz, 2H, Ar 3', 5'H),
6.89 (d, J=4Hz, 2H, Ar 3", 5"- H); 1.40-1.45(m, 6H, -
CH3), 4.03-4.12 (m, 4H, -CH2),
m/z(relative intensity%):
297[M+1]+(15),
1j
1640 (>C=O in conjugation with C=C),
1596,1570(>C=C< in conjugation with
C=O), 1510,1458(C=C aromatic stretching)
1253 & 1045 (C-O asymmetric &
symmetric stretching)
319[M+Na]+(100), 615[2M+Na]+ (22)
Table 8. Anti-Inflammatory Activity of the Synthesized Compounds
Compound
1a
Dose mg/kg, i.p
Change in paw edema mean±SEM in mm
% Activity
3rd hour
4th hour
3rd hour
4th hour
25
50
5.15±1.93
4.62±1.72
3.95±2.56a
4.68±1.32
4.39±2.15
3.78±2.13a
4.97±1.78
4.53±1.67
3.85±2.08a
4.29±1.45a
3.40±1.83a
2.76±2.34a
4.11±2.40a
3.12±1.37a
2.64±2.41
5.23±1.32
4.79±1.63
3.98±2.04a
4.98±2.38
4.52±1.42a
3.86±2.44a
5.14±1.57
4.64±2.31a
3.90±2.34a
4.78±1.63
4.47±1.61a
3.79±2.03a
4.57±2.43
3.45±1.31a
2.89±2.49a
5.68±1.21
2.02±1.42b
5.19±2.23
4.70±1.89
2.85±1.89a
3.51±1.43a
2.92±1.67a
2.29±1.36b
4.01±1.89a
3.62±2.03a
2.85±1.48b
3.34±1.98a
2.67±2.34b
1.80±2.61b
3.37±1.56a
2.57±1.73b
1.72±2.53
5.27±1.34
4.85±1.90
2.90±1.89a
4.15±2.00a
3.66±2.13a
2.67±1.45a
4.38±1.43a
4.64±1.85a
2.81±1.38a
3.57±2.07a
2.99±1.32a
2.21±1.52b
3.47±2.04a
2.81±2.34a
2.34±2.73b
9.3
8.6
18.6
30.4
17.6
22.7
33.4
12.5
20.2
32.2
24.4
40.1
51.4
27.6
45.0
53.5
7.8
17.2
49.8
38.2
48.5
59.8
29.4
36.2
57.5
41.1
52.9
68.3
40.6
54.7
69.7
7.2
100
25
1b
1c
1d
1e
1f
50
100
25
50
100
25
50
100
25
50
100
25
50
15.6
29.9
12.2
20.3
32.0
9.5
14.6
48.9
26.9
35.5
52.9
22.8
33.8
50.5
37.1
47.5
61.8
38.9
50.5
58.8
100
25
1g
1h
1i
50
100
25
50
18.2
31.3
15.8
21.3
33.2
19.5
39.2
49.1
100
25
50
100
25
1j
50
100
Control
Indomethacin
10
2.13±2.11b
64.4
62.5
n = 6, Values are mean ± S.E.M., a =p<0.05, b= p<0.001, significantly different from control.

486 Letters in Drug Design & Discovery, 2012, Vol. 9, No. 5
Choudhary et al.
response at 3-5 h. From the results obtained (summarized in
Table 8), all the synthesized compounds show a dose
dependent inhibition of edema, with an increase in activity
from 25 mg/kg to 50 mg/kg and to 100mg/kg doses.
dimethylamino chalcone (1e &1d), predicted as active by
best QSAR model, together with 1f predicted to be low
activity, was confirmed by in vitro inhibition of lipid
peroxidation assay method. Compounds 1e & 1d exhibited
the highest lipid peroxidation inhibitory activity (IC50
2.47µg/ml,3.1 µg/ml), where as compound 1f having lowest
activity (IC50 17.6 µg/ml). For these chalcones (compounds
1d, 1e, 1i and 1j), presence of electron donating groups on p-
position of both rings A and B seems to enhance activity,
whereas the presence of electron donating groups on p-
position of rings A and electron withdrawing groups on p-
position of ring B leads to compounds 1a.1b, 1c,1f,1g, and1h
with good to moderate activity.
At 25 and 50 doses all the compounds except 1a and 1f,
showed increase in activity from third hour to fourth hour.
At 100 mg/kg, 1d and 1e at the fourth hour showed greater
activity in comparison with the reference drug. However, the
anti-inflammatory activity of the reference drug
(indomethacin) was reduced during the same time. This may
probably due to difference in the mechanism of action of
these compounds. It can be deduced from the above that the
synthesized compounds have antioxidant properties (like
other flavanoids).
The compound 1e and 1d exhibited the highest activity
(IC50 2.47µg/ml,3.1 µg/ml). The lipid per oxidation
inhibitory activity of the compound is related with their
electron donating ability to a lipid radical and converting it
to a non-radical form. These reducing compounds can
terminate radical chain reactions and reduce hydro peroxides
and epoxides to less reactive derivatives. In lipid per
oxidation assay, malondialdehyde (MDA) is formed during
the oxidative degeneration as a product of free radicals,
which is accepted as an indicator of lipid per oxidation [29].
The peroxidation of membrane lipids initiated by oxygen
radicals may lead to cell injury. The synthesized chalcones
caused a reduction in cell membrane damage by decreasing
This is evident in the increase in activities at the fourth
hour in comparison with indomethacin, which had reduced
activity at this time; indomethacin is, however, a well-known
non-specific COX enzyme inhibitor. This result points to the
conclusion that the compounds synthesized may not act in
the same manner as indomethacin. The anti-inflammatory
response of synthesized chalcones may be by scavenging of
OH or super oxide radicals, and interrupting ROS mediated
signaling pathways such as inhibiting lipid per oxidation,
inhibit the activation of NF-κB[28].
b. In Vivo Antioxidant Activity (Inhibition of Lipid
Peroxidation)
the MDA production. They showed
a concentration
dependent inhibition of the lipid per oxidation. The results
obtained in the present study may be attributed to several
reasons like inhibition of ferryl-perferryl complex formation,
scavenging of OH or super oxide radicals or by the changing
the ratio of Fe3+/Fe2+, reducing the rate of conversion of
ferrous to ferric or by chelation of iron itself[30].
All the synthesized compounds were evaluated for
antioxidant activity by ferrous sulphate induced lipid
peroxidation. It is based on the inhibition of lipid
peroxidation, provides
a measure of how efficiently
antioxidants protect against lipid peroxidation.
From the results obtained, all compounds effectively
inhibit lipid peroxidation in a concentration dependent
manner measured in terms of pink colored TBA-MDA
complex (Table 9).
c. Antiulcer Activity
All compounds were evaluated for their gastro protective
properties in the rats by indomethacin-induced gastric
damage. Gastro protective activity was measured in terms of
% anti-ulcer activity as represented in Table 10, in which all
compounds at the tested dose level exhibited varying degree
of activity against ulceration induced by indomethacin.
The experimental data concerning the effect on lipid
peroxidation of synthesized compounds was related to their
chemical structures designed by best QSAR model. Two
Table 9. Effect of Synthesized Compounds on Lipid Peroxidation Inhibition
S N
Quantity in micrograms (µg/ml), Mean ± S.E.M.
IC50(µg/ml)
0.1
0.2
0.4
0.8
1.6
3.2
6.4
12.8
25.6
*Ex
*Pr
1a
1b
1c
1d
1e
1f
0.3±0.35
0.7±0.14
0.2±0.47
1.2±0.14
1.7±0.45
0.1±0.31
0.5±0.36
0.47±1.3
0.8±0.43
0.8±0.58
1.08±1.3
1.5±0.78
1.06±0.94
2.7±1.76
4.2±2.3
1.7±0.82
2.2±1.3
1.5±1.5
4.1±2.3
9.0±2.4
1.2±1.3
2.2±0.85
2.23±2.1
2.4±2.1
3.7±1.32
4.5±1.8
6.7±1.3
4.3±1.5
18±3.2
6.1±1.7
16.2±2.4
5.8±2.6
13.5±1.9 27.2±1.3
34±2.9 51±2.1
12.7±1.6 26.8±2.1
53±1.8
-
12.02
5.70
11.84
3.1
5.95
2.27
5.71
1.46
0.32
9.86
4.62
5.29
2.82
1.78
-
-
54.3±2.4
-
39.2±3.7 73.0±3.2 85.2±2.9
-
-
25.1±2.1 58.0±1.9 88.1±4.7 93.2±2.6
-
-
2.47
17.6
5.9
0.9±1.7
4.2±1.6
6.5±0.6
6.2±1.4
7.1±2.2
9.4±1.3
5.6±2.4
15.9±2.7
11±1.8
12.1±1.7 26.5±3.2
32±2.4 51.6±2.3
21.1±1.2 45.3±1.5
48.3±2.6
64.1±3.5
1g
1h
1i
1.3±0.73
1.25±1.22
1.6±0.43
2.4±1.1
-
-
-
-
-
64.0±2.7
9.14
4.8
17.2±0.9 39.0±3.2 64.0±1.8
22.5±2.3 48.1±2.1 79.0±1.9
-
-
1j
3.87
*Ex = Experimental value, *Pr = Predicted value.

Design, Synthesis and Evaluation of Chalcone Derivatives
Letters in Drug Design & Discovery, 2012, Vol. 9, No. 5 487
Table 10. The Gastroprotective Activity of the Test Compounds
Compounds
Doses (mg/kg, p.o.)
No. of ulcer spots counted
% Anti-ulcer activity
1a
100
100
100
100
100
100
100
100
100
100
50
8.20±0.36a
11.30±0.47b
16.40±0.39b
6.10±0.87a
5.10±0.74a
10.30±0.38a
12.30±0.45b
17.00±0.31b
9.50±0.63a
5.70±0.92a
24.90±0.63
67.1
54.6
34.1
75.5
79.5
58.6
50.6
31.7
61.8
77.1
1b
1c
1d
1e
1f
1g
1h
1i
1j
Indomethacin
n = 6, Values are mean ± S.E.M., a =p<0.05, b= p<0.001, significantly different from control.
[3]
[4]
Silakari, P.; Shrivastava, S.D.; Silakari, G.; Kohli, D.V.; Rambabu
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The Compounds 1e, 1j & 1d showed excellent activity
(72-79%), whereas compounds1a &1i exhibited good to
moderate (61-69%) activity. In addition, compounds 1h and
1c showed very less gastro protective action as indicated by
their high ulcer score.
The synthesized chalcones caused a reduction in gastric
damage. The result obtained in the present study may be
attributed to their antioxidant activity through scavenging of
ROS and protection of GPO [31].
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CONCLUSION
[7]
In summary we have designed, synthesized and
evaluated novel chalcones for their biological studies. 4-
[8]
Dimethylamino-4’-ethoxychalcone
(1e)
and
4-
Dimethylamino-4’-methoxychalcone (1d) have increasing
anti-inflammatory activity than reference drug. Moreover,
the same compounds also obtained promising antioxidant
and antiulcer activities. The results of this study may find a
lead (1e) towards the development of new therapeutic agent
against inflammation.
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Rao, Y.K.; Fang, S.H.; Tzeng, Y.M. Differential effects of
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2679–2686.
Herencia, F.; Ferrandiz, M.L.; Ubeda, A.; Guillen, I.; Chan, G.M.
4-Dimethyl-amino-3′, 4′-dimethoxychalcone downregulates iNOS
expression and exerts anti-inflammatory effects. Free Radical.
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Okawa, M.; Kinjo, J.; Nohara, T.; Ono, M. DPPH radical
scavenging activity of flavanoids obtained from medicinal plants.
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CONFLICT OF INTEREST
Declared none.
ACKNOWLEDGEMENTS
Authors owe a deep sense of gratitude to Prof. V. P. S.
Arora, Honorable Vice Chancellor, Kumaun University,
Nainital for providing facilities for this work.
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