Synthesis and evaluation of antiinflammatory activity of substituted chalcone derivatives

Article abstract of DOI:10.1007/s00044-009-9202-z

In an effort to develop potent antiinflammatory agents, a series of substituted chalcone derivatives was synthesized and evaluated for antiinflammatory activity through monitoring of their ability to inhibit xylene-induced ear edema in mice. Some of the tested compounds exhibited significant activity, and compounds 3f [(E)-1-(2,4-dihydroxyphenyl)-3-(4- dimethylamino)phenyl)prop-2-en-1-one] and 3h [(E)-3-(4-chlorophenyl)-1-(2,4- dihydroxyphenyl)prop-2-en-1-one] showed the highest antiinflammatory activity (62 and 68% inhibition, respectively, 2 h before administration), comparable with or even slightly more potent than the reference drug ibuprofen (53%). Furthermore, the structure-activity relationship of these substituted chalcone derivatives was demonstrated.

Full text of DOI:10.1007/s00044-009-9202-z

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2010) 19:403–412
DOI 10.1007/s00044-009-9202-z
ORIGINAL RESEARCH
Synthesis and evaluation of antiinflammatory activity
of substituted chalcone derivatives
Xue-Wu Zhang Æ Dong-Hai Zhao Æ Ying-Chun Quan Æ
Liang-Peng Sun Æ Xiu-Mei Yin Æ Li-Ping Guan
Received: 16 August 2008 / Accepted: 20 March 2009 / Published online: 23 April 2009
¨
Ó Birkhauser Boston 2009
Abstract In an effort to develop potent antiinflammatory agents, a series of
substituted chalcone derivatives was synthesized and evaluated for antiinflamma-
tory activity through monitoring of their ability to inhibit xylene-induced ear edema
in mice. Some of the tested compounds exhibited significant activity, and com-
pounds 3f [(E)-1-(2,4-dihydroxyphenyl)-3-(4-dimethylamino)phenyl)prop-2-en-1-
one] and 3h [(E)-3-(4-chlorophenyl)-1-(2,4-dihydroxyphenyl)prop-2-en-1-one]
showed the highest antiinflammatory activity (62 and 68% inhibition, respectively,
2 h before administration), comparable with or even slightly more potent than the
X.-W. Zhang ꢀ L.-P. Guan (&)
Ministry of Education, Key Laboratory of Organism Functional Factors of the Changbai Mountain,
Yanbian University, No. 121, JuZi Street, Yanji City, Jilin Province, People’s Republic of China
e-mail: glp730@yahoo.com.cn
X.-W. Zhang
Basic Medical College, Yanbian University, No. 121, JuZi Street, Yanji City,
Jilin Province, People’s Republic of China
e-mail: zhangxuewu@ybu.edu.cn
D.-H. Zhao
Jilin Medical College, No. 5, Jilin Street, Jilin City, Jilin Province 132013,
People’s Republic of China
e-mail: zdh1027@sina.com
Y.-C. Quan ꢀ L.-P. Sun ꢀ X.-M. Yin ꢀ L.-P. Guan
College of Pharmacy, Yanbian University, No. 121, JuZi Street, Yanji City,
Jilin Province, People’s Republic of China
Y.-C. Quan
e-mail: ycquan1969@yahoo.com.cn
L.-P. Sun
e-mail: lpsun@ybu.edu.cn
X.-M. Yin
e-mail: yinxm@ybu.edu.cn

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Med Chem Res (2010) 19:403–412
reference drug ibuprofen (53%). Furthermore, the structure–activity relationship of
these substituted chalcone derivatives was demonstrated.
Keywords Antiinflammatory ꢀ Chalcone derivatives ꢀ Ibuprofen ꢀ
Synthesis
Introduction
Nonsteroidal antiinflammatory drugs (NSAIDs) are useful tools in the treatment of
acute and chronic inflammation, pain, and fever. However, long-term clinical usage
of NSAIDs is associated with significant side effects including gastrointestinal
lesions, bleeding, and nephrotoxicity (Hallas et al., 1995; Mccarthy, 1998; Raskin,
1999). Therefore, the discovery of new and safer antiinflammatory drugs represents
a challenging goal for such a research area (Van and Botting, 1995). Because
resistance to antiinflammatory drugs is widespread, there is an increasing need for
identification of novel structure leads that may be of use in designing new, potent,
and less toxic antiinflammatory agents.
Chalcone derivatives, among the large families of plant constituents, have various
therapeutic benefits including antioncogenic, antiinflammatory, analgesic, antiul-
cerative, antiviral, antibacterial, antifungal, and antimalarial properties (Bekhit et al.,
2001; Hiseh et al., 1998; Kumar et al., 2003; Liu et al., 2001; Lopez et al., 2001;
Murakami et al., 1991; Viana et al., 2003; Wu et al., 2003). Furthermore, it is
reported that 20,50-dihydroxychalcones derivatives possess antiinflammatory activity
(Won et al., 2005), and 3,4-dihydroxychalcones is reported to be a 5- or 12-
lipoxygenase and cyclooxygenase inhibitor (Sogawa et al., 1993).
Ballesteros et al. (1995) reported that two synthetic 20-hydroxychalcones exerted
topical antiinflammatory effects in mice. Lee et al. (2006) reported 20,40,60-
tris(methoxy)chalcone to be an antiinflammatory compound that reduces nitric
oxide (NO) production by inhibiting inducible NO synthase expression. The
findings suggest that some chalcones may be promising antiinflammatory agents.
In our previous studies (Guan et al., 2005), 1-(2,4-dihydroxyphenyl)-3-(3,4-
dihydroxyphenyl) prop-2-en-1-one and 1,3-bis(4-hydroxyphenyl)prop-2-en-1-one
were tested for their protective effects. Because the two compounds have a chalcone
structure, they were assumed to possess antiinflammatory activity. Therefore, in view
of the observations, we designed and synthesized a series of 20,40-dihydroxychalcones
or 40-hydroxychalcones and varied the substitution of the B ring to the screen for their
antiinflammatory effects in vivo. We discuss their structure–activity relationships.
Materials and methods
Chemistry
Melting points were determined in open capillary tubes and are uncorrected.
Infrared (IR) spectra were recorded (in KBr) on an FT-IR1730 (Bruker Biospin,

Med Chem Res (2010) 19:403–412
1
405
Switzerland), and H-NMR spectra were measured on an AV-300 (Bruker Biospin,
Switzerland). All chemical shifts are given in ppm relative to tetramethysilane.
Mass spectra were measured on an HP1100LC (Agilent Technologies, Shelton,
USA). Elemental analyses were performed on a 204Q CHN (Pekin-Elmer, Shelton,
USA). Microanalyses of C, N, and H were performed using a Heraeus CHN Rapid
Analyzer (Hanau, Hessen Land, Germany). All other chemicals were of analytical
grade. The synthesis of 1-(2,4-dihydroxyphenyl)ethanone (Fan, 1992) (1) and
1-(4-hydroxyphenyl)ethanone (Fan, 1992) (2) was as previously reported.
General procedure for the preparation of (E)-1-(2, 4-dihydroxyphenyl)-3-
phenylprop-2-en-1-one (3)
In a round-bottomed flask, substituted benzaldehyde (1.0 g, 6 mmol) and 1-(2,4-
dihydroxyphenyl)ethanone (0.46 g, 3 mmol) were dissolved in ethylene glycol.
Boric acid (0.70 g, 11.3 mmol) was added, and the mixture was refluxed at 120°C
for 6 h. Solvents were removed under reduced pressure, and the residue was
extracted three times with diethyl ether 30 mL. The diethyl ether layer was washed
three times with water (30 mL 9 3) and dried over anhydrous MgSO4. After
removal of the solvents, the product was purified by silica gel column chromatog-
raphy (petroleum benzine: acetic ether = 2:1).
(E)-1-(2,4-dihydroxyphenyl)-3-(3,4-dihydroxyphenyl)prop-2-en-1-one (3a) Yield:
32%; mp: 213–215°C. IR (KBr) cm-1: 3370 (–OH str.), 1685 (C=O str.), 3045
(Ar C–H str.), 1590, 1480, 1430 (C=C ring str), 1223 (C–O str.), 749 (C–H out of
1
plane bending); H-NMR (CDCl3): d = 6.30 (d, J = 15 Hz, 1H, =CH), 6.82–6.92
(m, 3H, –C6H3), 7.25–7.28 (m, 3H, –C6H3), 7.63 (d, J = 15 Hz, 1H, =CH), 10.58
(s, 1H, –OH), 13.60 (s, 1H, –OH); MS m/z: 273 (M?1). Anal. for C15H12O5: Calc.
C: 66.17, H: 4.44. Found C: 66.01, H: 4.15.
(E)-1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one
(3b) Yield:
32.5%; mp: 180–182°C. IR (KBr) cm-1: 3384 (–OH str.), 1685 (C=O str.), 3042
(Ar C–H str.), 1591, 1482, 1430 (C=C ring str), 1222 (C–O str.), 750 (C–H out of
plane bending); 1H-NMR (CDCl3): d = 6.72–6.97 (m, 3H, –C6H3), 7.31 (d,
J = 15 Hz, 1H, =CH), 7.73–7.79 (m, 4H, –C6H4), 8.09 (d, J = 15 Hz, 1H, =CH),
10.10 (s, 1H, –OH), 10.64 (s, 1H, –OH); MS m/z: 257 (M?1). Anal. for C15H12O4:
Calc. C: 70.31, H: 4.72. Found C: 70.21, H: 4.56.
(E)-1-(2,4-dihydroxyphenyl)-3-(4-hydroxy-3-methoxyphenyl)prop-2-en-1-one (3c)
Yield: 56%; mp: 192–194°C. IR (KBr) cm-1: 3384 (–OH str.), 1690 (C=O str.),
3041 (Ar C–H str.), 1590, 1481, 1432 (C=C ring str), 1223 (C–O str.), 748 (C–H out
of plane bending); 1H-NMR (CDCl3): d = 3.32 (s, 3H, 3-OCH3), 6.56–6.89 (m, 3H,
–C6H3), 7.52 (d, J = 15 Hz, 1H, =CH), 7.70–7.79 (m, 3H, –C6H4), 8.14 (d,
J = 15 Hz, 1H, =CH), 10.55 (s, 1H, –OH), 10.67 (s, 1H, –OH); MS m/z: 287
(M?1]). Anal. for C16H14O5: Calc. C: 67.13, H: 4.93. Found C: 67.05, H: 4.88.

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(E)-1-(2, 4-dihydroxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one (3d) Yield: 38%;
mp: 166–168°C. IR (KBr) cm-1: 3388 (–OH str.), 1690 (C=O str.), 3041 (Ar C–H str.),
1590, 1481, 1432 (C=C ring str), 1223 (C–O str.), 748 (C–H out of plane bending); 1H-
NMR (CDCl3): d = 3.87 (s, 3H, 4-OCH3), 6.44–6.95 (m, 3H, –C6H3), 7.43 (d,
J = 15 Hz, 1H, =CH), 7.85–8.06 (m, 4H, –C6H4), 7.91 (d, J = 15 Hz, 1H, =CH),
12.70 (s, 1H, –OH), 13.50 (s, 1H, –OH); MS m/z: 271 (M?1). Anal. for C16H14O4:
Calc. C: 71.10, H: 5.22. Found C: 70.98, H: 5.13.
(E)-3-(benzo[d][1,3]dioxol-5-yl)-1-(2,4-dihydroxyphenyl)prop-2-en-1-one
(3e)
Yield: 39%; mp: 168–170°C. IR (KBr) cm-1: 3384 (–OH str.), 1690 (C=O str.),
3045 (Ar C–H str.), 1590, 1480, 1435 (C=C ring str), 1223 (C–O str.), 748 (C–H out of
plane bending); 1H-NMR (CDCl3): d = 2.56 (s, 2H, 3,4-OCH2O), 6.88–6.97 (m, 3H,
–C6H3), 6.95 (d, J = 15 Hz, 1H, =CH), 7.18–7.44 (m, 3H, –C6H4), 7.42
(d, J = 15 Hz, 1H, =CH), 12.70 (s, 1H, –OH), 13.46 (s, 1H, –OH); MS m/z: 285
(M?1). Anal. for C16H12O5: Calc. C: 67.60, H: 4.25. Found C: 67.55, H: 4.18.
(E)-1-(2, 4-dihydroxyphenyl)-3-(4-dimethylamino)phenyl)prop-2-en-1-one (3f)
Yield: 53%; mp: 180–182°C. IR (KBr) cm-1: 3378(–OH str.), 1690 (C=O str.),
3045 (Ar C–H str.), 1590, 1480, 1435 (C=C ring str), 1223 (C–O str.), 748 (C–H out of
plane bending); 1H-NMR (CDCl3): d = 3.29 [s, 6H, 4-N(CH3)2], 6.44–6.89 (m, 3H,
–C6H3), 6.70(d, J = 15 Hz, 1H, =CH), 7.78–7.89(m, 4H, –C6H4), 8.09(d, J = 15 Hz,
1H, =CH), 10.61 (s, 1H, –OH), 11.62 (s, 1H, –OH); MS m/z: 284 (M?1). Anal. for
C17H17NO3: Calc. C: 72.07, H: 6.05, N 4.94. Found C: 72.01, H: 5.90, N 4.79.
(E)-1-(2,4-dihydroxyphenyl)-3-p-tolylprop-2-en-1-one (3g) Yield: 46%; mp: 184–
186°C. IR (KBr) cm-1: 3374 (–OH str.), 1691 (C=O str.), 3045 (Ar C–H str.), 1590,
1482, 1434 (C=C ring str), 1221 (C–O str.), 749 (C–H out of plane bending); H-
1
NMR (CDCl3):d = 2.16 (s, 3H, –CH3), 6.75–6.87 (m, 3H, –C6H3), 6.75 (d,
J = 15 Hz, 1H, =CH), 7.25–7.48 (m, 4H, –C6H4), 7.41 (d, J = 15 Hz, 1H, =CH),
11.70 (s, 1H, –OH), 12.36 (s, 1H, –OH); MS m/z: 255 (M?1). Anal. for C16H14O3:
Calc. C: 75.57, H: 5.55. Found C: 75.46, H: 5.40.
(E)-3-(4-chlorophenyl)-1-(2,4-dihydroxyphenyl)prop-2-en-1-one
(3h) Yield:
35.8%; mp: 156–158°C. IR (KBr) cm-1: 3374 (–OH str.), 1692 (C=O str.), 3042
(Ar C–H str.), 1591, 1482, 1435 (C=C ring str), 1221 (C–O str.), 749 (C–H out of
plane bending); 1H-NMR (CDCl3): d = 6.42–6.51 (m, 3H, –C6H3), 7.47 (d,
J = 15 Hz, 1H, =CH), 7.66–7.89 (m, 4H, –C6H4), 8.05 (d, J = 15 Hz, 1H, =CH),
12.71 (s, 1H, –OH), 13.20 (s, 1H, –OH); MS m/z: 275 (M?1). Anal. for
C15H11ClO3: Calc. C: 65.58, H: 4.04. Found C: 65.46, H: 3.95.
(E)-1-(2,4-dichlorophenyl)-3-(2,4-dihydroxyphenyl)prop-2-en-1-one (3i) Yield:
54%; mp: 154–156°C. IR (KBr) cm-1: 3480 (–OH str.), 1693 (C=O str.), 3045
(Ar C–H str.), 1590, 1484, 1435 (C=C ring str), 1223 (C–O str.), 749 (C–H out of
plane bending); 1H-NMR (CDCl3): d = 6.47–6.52 (m, 3H, –C6H3), 7.45
(d, J = 15 Hz, 1H, =CH), 7.64–7.80 (m, 3H, –C6H4), 8.21 (d, J = 15 Hz,

Med Chem Res (2010) 19:403–412
407
1H, =CH), 12.71 (s, 1H, –OH), 13.25 (s, 1H, –OH); MS m/z: 309 (M?1). Anal. for
C15H10Cl2O3: Calc. C: 58.28, H: 3.26. Found C: 58.15, H: 3.08.
(E)-1-(2,4-dihydroxyphenyl)-3-(2-nitrophenyl)prop-2-en-1-one (3j) Yield: 37%;
mp: 200–202°C. IR (KBr) cm-1: 3384 (–OH str.), 1692 (C=O str.), 3043 (Ar C–
H str.), 1591, 1480, 1435 (C=C ring str), 1223 (C–O str.), 750 (C–H out of plane
1
bending); H-NMR (CDCl3): d = 6.36–6.42 (m, 3H, –C6H3), 7.86 (d, J = 15 Hz,
1H, =CH), 7.78–8.04 (m, 4H, –C6H4), 8.06 (d, J = 15 Hz, 1H, =CH), 10.70 (s, 1H,
–OH), 10.84 (s, 1H, –OH); MS m/z: 286 (M?1). Anal. for C15H11NO5: Calc. C:
63.16, H: 3.89, N: 4.91. Found C: 63.02, H: 3.78. N: 4.84.
(E)-1-(2, 4-dihydroxyphenyl)-3-(3-nitrophenyl)prop-2-en-1-one (3k) Yield: 38%.
mp 210–212°C. IR (KBr) cm-1: 3388 (–OH str.), 1690 (C=O str.), 3043 (Ar C–H
str.), 1592, 1481, 1435 (C=C ring str), 1223 (C–O str.), 749 (C–H out of plane
1
bending). H-NMR (CDCl3): d = 7.73–7.79 (m, 3H, –C6H3), 7.93 (d, J = 15 Hz,
1H, =CH), 8.31–8.43 (m, 4H, –C6H4), 8.24 (d, J = 15 Hz, 1H, =CH), 10.66 (s, 1H,
–OH), 12.58 (s, 1H, –OH). MS: m/z 286 [M?1]. Anal. Calcd. For C15H11NO5: C
63.16, H 3.89, N 4.91. Found: C 63.01, H 3.75. N 4.82.
General Procedure for the preparation of (E)-1-(4-dihydroxyphenyl)-3-phenylprop-
2-en-1-one (4)
In a round-bottomed flask, substituted benzaldehyde (1.0 g, 6 mmol) and 1-(4-
hydroxyphenyl)ethanone (0.46 g, 3 mmol) were dissolved in ethylene glycol. Boric
acid (0.70 g, 11.3 mmol) was added, and the mixture was refluxed at 120°C for 6 h.
The solvents were removed under reduced pressure, and the residue was extracted
three times with diethyl ether 30 mL. The diethyl ether layer was washed three
times with water (30 mL 9 3) and dried over anhydrous MgSO4. After removal of
the solvents, the product was purified by silica gel column chromatography
(petroleum benzine: acetic ether = 2:1).
(E)-1,3-bis(4-hydroxyphenyl)prop-2-en-1-one (4a) Yield:36%; mp:196–198°C. IR
(KBr) cm-1: 3388 (–OH str.), 1691 (C=O str.), 3045 (Ar C–H str.), 1590, 1484, 1432
(C=C ring str), 1222 (C–O str.), 748 (C–H out of plane bending); 1H-NMR (CDCl3):
d = 6.89–6.95 (m, 4H, –C6H4), 7.33 (d, J = 15 Hz, 1H, =CH), 7.59–7.87 (m, 4H,
–C6H4), 7.99 (d, J = 15 Hz, 1H, =CH), 9.67 (s, 1H, –OH), 9.95 (s, 1H, –OH); MS m/z:
241 (M?1). Anal. for C15H12O3: Calc. C: 74.99, H: 5.03. Found C: 74.86, H: 4.90.
(E)-3-(4-dimethylamino)phenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one (4b) Yield:
48%; mp: 182–184°C. IR (KBr) cm-1: 3384 (–OH str.), 1693 (C=O str.), 3041 (Ar
C–H str.), 1590, 1482, 1433 (C=C ring str), 1222 (C–O str.), 747 (C–H out of plane
bending); 1H-NMR (CDCl3): d = 2.98 [s, 6H, 4-N(CH3)2], 6.87–6.93 (m, 4H,
–C6H4), 7.35 (d, J = 15 Hz, 1H, =CH), 7.93–8.12 (m, 4H, –C6H4), 7.82
(d, J = 15 Hz, 1H, =CH), 9.75 (s, 1H, –OH); MS m/z: 268 (M?1). Anal. for
C17H17NO2: Calc. C: 76.38, H: 6.41, N: 5.24. Found C: 76.26, H: 6.30, N: 5.13.

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(E)-3-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one (4c) Yield:
39%; mp: 216–218°C. IR (KBr) cm-1: 3384 (–OH str.), 1690 (C=O str.), 3043 (Ar C–
H str.), 1590, 1484, 1435 (C=C ring str), 1221 (C–O str.), 749 (C–H out of plane
bending); 1H-NMR (CDCl3): d = 3.79 (s, 3H, 3-OCH3), 6.89–7.01 (m, 3H, –C6H3),
7.23 (d, J = 15 Hz, 1H, =CH), 7.35–7.86 (m, 4H, –C6H4), 7.97 (d, J = 15 Hz,
1H, =CH), 9.74 (s, 1H, –OH), 10.65 (s, 1H, –OH); MS m/z: 271 (M?1). Anal. for
C16H14O4: Calc. C: 71.10, H: 5.22. Found C: 71.01, H: 5.09.
Pharmacology
The antiinflammatory activity was evaluated by an in-vivo inhibition assay
monitoring xylene-induced ear edema. All tested compounds were homogenized
with 0.5% sodium carboxymethylcellulose (CMC-Na) and administered orally to
kunming mice (body weight, 20–25 g; 10 animals per group). Control mice received
the vehicle only (0.5% sodium carboxymethylcellulose, 0.2 mL/20 g).
At a specified later time, 20 lL of xylene was applied to the surface of the right
ear of each mouse by a micropipette. The mice were killed 30 min later, and a
cylindrical plug (diameter, 7 mm) was excised from each of the treated and
untreated ears. Edema was quantified by the difference in weight between the two
plugs. The antiinflammatory activity was expressed as a percentage of edema
reduction compared with the CMC-Na-administered control group.
The NSAID drug ibuprofen was tested in parallel as an activity reference. Edema
values, expressed as mean standard deviation, were compared statistically using
Student’s t test. A p value less than 0.05 was adopted as the test of significance.
Results and discussion
The synthesis of the target compounds was accomplished according to the reaction
sequence illustrated in Scheme 1. Compound 1 was synthesized using resorcine and
acetic acid in the presence of zinc chloride as the catalyst in a good yield (Fan,
1992). Compound 2 was obtained with nitrobenzene through Fries rearrangement in
the presence of aluminium trichloride as the catalyst (Fan, 1992). Derivatives 3 and
4 were prepared by Claisen-Schmidt condensation with compounds 1 and 2,
respectively.
As shown in Table 1, the evaluation indicated that the 13 synthetic compounds
showed antiinflammatory activity at a dose of 200 mg/kg administered orally 2 h
before the inflammatory agent xylene. Among the synthesized compounds, 3f [(E)-
1-(2,4-dihydroxyphenyl-3-(4-dimethylamino)phenyl)prop-2-en-1-one] and 3h [(E)-
3-(4-chlorophenyl)-1-(2, 4-dihydroxyphenyl)prop-2-en-1-one] showed the highest
ear inflammation inhibition rate: 62.55% and 68.17%, respectively.
First, compared with the substituted 40-hydroxychalcone derivatives, the antiin-
flammatory activity of the substituted 20,40-dihydroxychalcone derivatives was
stronger than that of 40-hydroxychalcone. As shown in Table 1, compound 3f
(inhibition rate, 62.55%) showed a stronger inhibitory effect than compound 4b

Med Chem Res (2010) 19:403–412
409
B
A
O
H
O
R
R
HO
HO
OH
CH3COOH
ZnCl2
HO
COCH3
H3BO4, HOCH2CH2OH
OH
OH
O
1
3
R
3a = -3,4-(OH)2
3f = -4-N(CH3)2
3f = -3-NO2
3b = -4-OH
3g = -4-CH3
3c = -3-OCH3-4-OH
3h = -4-Cl
3d = - 4-OCH3
3i = -2,4-Cl2
3e = -3,4-OCH2O-
3j = -2-NO2
H
R
R
HO
O
AlCl3
C6H5NO2
COCH3
HO
COCH3
H3BO4, HOCH2CH2OH
O
2
4
R
4a = -4-OH
4b = -4-N(CH3)2
4c = -3-OCH3-4-OH
Scheme 1 The synthesis route of compounds 3a–j and 4a–c
(inhibition rate, 17.27%). Similarly, compounds 3b and 3c (inhibition rate, 14.86 and
25.20%, respectively) rather than compounds 4a and 4c (inhibition rate, 5.42 and
7.83%, respectively) resulted in greater antiinflammatory activity. It seemed that the
increase of the hydroxyl group on the chalcone A ring could influence the inhibitory
effect on antiinflammatory activity, but the potency depended on the variation in the
substituent of the B ring.
Second, for the substituted 20,40-dihydroxychalcone derivatives 3a–g, all except
one of these compounds (3g) had the antiinflammatory activities. Compound 3f
exhibited significantly greater activity than the reference drug ibuprofen. The
position of the substituted group on the phenyl ring greatly influenced the
antiinflammatory activity, with an activity order of –4-N(CH3)2 [ –4-OCH3 [
–3–OCH3-4-OH [ –3,4-OCH2O– [ –4-OH [ –3,4-(OH)2.
On the other hand, when the substitution was a member of atom Cl, the position
of atom Cl on the phenyl ring may have influenced the antiinflammatory activity,
with the potency order of the two Cl-substituted derivatives being 4-Cl [ 2,4-Cl2, in
which the compound 3h exhibited the most antiinflammatory activity. The
substitution was a member of the nitro group, with the potency order of the two
NO2-substituted derivatives being 3-NO2 [ 2-NO2. These results indicated that the

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Med Chem Res (2010) 19:403–412
Table 1 Antiinflammatory activity of compounds 3a–k and 4a–c administrated orally
Compound
R
Dose
(mg/kg)
No. of
mice
Edema
mean SD (mg)
Inhibition
rate (%)
CMC-Na
–
–
200
200
200
200
200
200
200
200
200
200
200
200
200
200
200
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
9.96 0.53
–
Ibuprofen
–
4.63 0.48***
8.53 0.52***
8.48 0.37***
7.45 0.24***
4.84 0.32***
7.77 0.53***
3.73 0.41***
10.92 0.64
53.51
14.36
14.86
25.20
51.41
21.99
62.55
–
3a
3b
3c
3d
3e
3f
–3,4-(OH)2
–4-OH
–3-OCH3-4-OH
–4-OCH3
–3,4-OCH2O–
–4-N(CH3)2
–4-CH3
3g
3h
3i
–4-Cl
3.17 0.33***
7.37 0.70***
7.95 0.39***
6.97 0.48***
9.42 0.34***
8.24 0.51***
9.18 0.36**
68.17
26.04
20.18
30.02
5.42
–2,4-Cl2
–2-NO2
3j
3k
4a
4b
4c
–3-NO2
–4-OH
–4-N(CH3)2
–3-OCH3-4-OH
17.27
7.83
** p \ 0.01
*** p \ 0.001 compared with the CMC-Na (control) group
character of the substitution on the B ring had a significant influence on the
antiinflammatory activity.
Based on the results of the screening shown in Table 1, two outstanding
derivatives, 3f and 3h, were chosen to be evaluated in the screening shown in the
Table 2. The dose still was 200 mg/kg administered orally, but multiple intervals
(0.5 h, 1 h, 2 h, 3 h, 4 h, and 24 h) for xylene application were assessed. As the
interval lengthened, the antiinflammatory activity of compounds 3f and 3h first
increased, then declined. The peak activity was observed at the 2-h interval.
Compound 3f showed stronger activity than compound 3h at all time points except
the 2-h point. Compound 3f showed significantly greater activity than the reference
drug ibuprofen 0.5 h after administration but comparable (1 h, 24 h) or lower (3 h,
4 h) activity at other time points, indicating its quick absorption and potential for
acute antiinflammatory action. Compound 3h showed an activity level similar to
that of the reference drug at all time points except at the 1-h time point, when it had
lower activity than ibuprofen.
Finally, as seen in Table 3, the ear inflammation inhibition rate of compounds 3f,
3h, and the reference drug ibuprofen (at lower doses of 100 and 50 mg/kg
administered 2 h before xylene application) were evaluated and compared.
Compound 3f showed effects similar to those of ibuprofen at the two lower doses,
whereas compound 3h possessed stronger antiinflammatory activity than ibuprofen
at 100 mg/kg.

Med Chem Res (2010) 19:403–412
411
Table 2 Antiinflammatory activity of compounds 3f and 3h administered at different times before the
xylene application
Time (h)
Dose (mg/kg)
Inhibition (%)
3f
3h
Ibuprofen
0.5
1
200
200
200
200
200
200
41.67a
45.81
62.55b
27.52a
25.29b
21.25
30.21
32.52a
68.17
33.56
32.26
21.46
32.54
41.62
53.51
34.51
30.10
20.59
2
3
4
24
a
p \ 0.01 compared with ibuprofen at the corresponding dose
p \ 0.01
b
Table 3 Antiinflammatory activity of compounds 3f and 3h at different doses
Time (h)
Dose (mg/kg)
Inhibition (%)
3f
3h
Ibuprofen
2
2
2
200
100
50
62.55a
32.93
15.12
68.17
48.98b
18.57
53.51
33.03
19.78
a
p \ 0.01
b
p \ 0.001 compared with ibuprofen at the corresponding dose
Conclusion
In conclusion, for a series of antiinflammatory compounds, the substitution of 20,
40-dihydroxychalcones or 40-hydroxychalcons was synthesized, and the resulting
antiinflammatory activity was evaluated by an in vivo test. Two of the compounds,
3f and 3h, exhibited antiinflammatory activity comparable with that of the reference
drug ibuprofen.
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