Synthesis of combretastatin analogs: Evaluation of in vitro anticancer activity and molecular docking studies

Article abstract of DOI:10.1007/s00044-011-9887-7

This study is based on the synthesis of a series of combretastatin analogs with different substitutions on one aryl moiety and a carboxylic group in connecting chain. Cis-configuration with respect to aryl groups was established by X-ray crystal analysis. All the synthesized compounds were evaluated for anticancer activity against a panel of cell lines. Six compounds 1a, 1b, 1c, 1k, 1n, and 1p showed marked anticancer activity against human colon (colo-205), lung (A549), ovary (IGROV-1), prostrate (PC-3), CNS (SF-295), leukemia (THP-1), and breast (MCF-7) cell lines. Out of these, 1b showed remarkable inhibitory activity comparable to paclitaxel against lung cancer cell line with IC50 3.9 μM. Importance of carboxylic group in the synthesized compounds was studied by flexible docking study of 1b which showed the importance of carboxylic group interactions with colchicine-binding site of ab-tubulin. Springer Science+Business Media, LLC 2011. Springer Science+Business Media, LLC 2011.

Full text of DOI:10.1007/s00044-011-9887-7

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2012) 21:3720–3729
DOI 10.1007/s00044-011-9887-7
ORIGINAL RESEARCH
Synthesis of combretastatin analogs: evaluation of in vitro
anticancer activity and molecular docking studies
•
Sunil Kumar Sameer Sapra Raj Kumar Manish Kumar Gupta
•
•
•
•
Surrinder Koul Tandeep Kour Ajit Kumar Saxena
•
•
•
Om Prakash Suri Kanahya Lal Dhar
Received: 26 July 2011 / Accepted: 5 November 2011 / Published online: 3 December 2011
Ó Springer Science+Business Media, LLC 2011
Abstract This study is based on the synthesis of a series
of combretastatin analogs with different substitutions on
one aryl moiety and a carboxylic group in connecting
chain. Cis-configuration with respect to aryl groups was
established by X-ray crystal analysis. All the synthesized
compounds were evaluated for anticancer activity against
a panel of cell lines. Six compounds 1a, 1b, 1c, 1k, 1n,
and 1p showed marked anticancer activity against human
colon (colo-205), lung (A549), ovary (IGROV-1), pros-
trate (PC-3), CNS (SF-295), leukemia (THP-1), and breast
(MCF-7) cell lines. Out of these, 1b showed remarkable
inhibitory activity comparable to paclitaxel against lung
cancer cell line with IC50 3.9 lM. Importance of car-
boxylic group in the synthesized compounds was studied
by flexible docking study of 1b which showed the
importance of carboxylic group interactions with colchi-
cine-binding site of ab-tubulin.
Introduction
Cancer is one of the major causes of death throughout the
world. In the U.S., the number of deaths caused by cancer is
second highest and next to that from the cardiovascular
diseases (Shewach and Kuchta, 2009). Tubulin, a validated
target in cancer chemotherapy plays an important role in the
formation of the mitotic spindle, which provides the struc-
tural framework for the physical segregation of the chro-
mosomes during the mitosis (Hadfield et al., 2003).
Combretastatin, binds to b-tubulin and strongly inhibit
tubulin polymerization by binding to the colchicine site
(Ouyang et al., 2006; Tron et al., 2006; Woods et al., 1995)
and disrupts the normal mitotic spindle function (McGown
and Fox, 1989), and its action may be through endothelial-
cadherin signaling pathway (Vincent et al., 2005). Com-
bretastatin was first isolated from the bark of African willow
tree Combretum caffrum (Pettit et al., 1987). Two synthetic
combretastatin analogs viz., D-24851 and ABT-75 are in
advanced phased clinical trials (Ouyang et al., 2006;
Stokvis et al., 2004). Plenty of combretastatin analogs
(Fig. 1) have been synthesized (Liou et al., 2004, 2008) till
date with different substituents on aryl rings. The structure–
activity relationship of these analogs reveals that methoxy
substituents in ring B are required for biological activity.
Furthermore, free hydroxyl group or other equivalent
hydrogen bonding donors at ring B are also essential for
activity (Furst et al., 2009). Combretastatin has low aqueous
solubility and Z-configured C–C double bond prone to
isomerization to E-form during storage and administration,
which results in dramatic reduction of activity (Bellina
et al., 2006). To overcome this isomerization problem
when heterocyclic rings viz., isoxazole, imidazole, triazole,
azetidinones, etc. were introduced in place of the ethene
bridge, however this also reduces activity because molecule
Keywords Anticancer ꢀ Combretastatin ꢀ
Molecular docking ꢀ Phenyl acetic acid ꢀ
Tubulin inhibitor
S. Kumar (&) ꢀ S. Sapra ꢀ R. Kumar ꢀ M. K. Gupta ꢀ
O. P. Suri ꢀ K. L. Dhar (&)
Department of Pharmaceutical Chemistry,
I.S.F. College of Pharmacy, Moga 142001, India
e-mail: suniliftm_1982@rediffmail.com
K. L. Dhar
e-mail: dharkl@yahoo.com
S. Koul ꢀ T. Kour ꢀ A. K. Saxena
Indian Institute of Integrative Medicine,
Jammu Tawi, Jammu 180001, India
123

Med Chem Res (2012) 21:3720–3729
3721
becomes planar, as molecular modeling study confirms that
combretastatin with ethene bridge has twisted geometries
preferred for binding to the colchicines binding site (Lee
et al., 2008; Kaffy et al., 2006). The structure-based mod-
eling studies have been reported to address important
structure–activity relationship for the combretastatins
(Brown et al., 1995; Nandy et al., 1991; Kong et al., 2005).
Recently, Ducki et al. (2009) described a docking model
for tubulin–combretastatin interactions and compared with
colchicine. These studies suggested that the combretastatins
show similar binding mode as colchicine and fit well at the
colchicine-binding site of tubulin and interaction energies
of the compounds with colchicine-binding sites were also
calculated (Bellina et al., 2006). The structure-based mod-
eling studies have been reported to address important
structure–activity relationship for the combretastatins
(Brown et al., 1995; Nandy et al., 1991; Kong et al., 2005).
A key structural feature is the presence of double bond
forcing the two aromatic rings to stay within an appropriate
distance is therefore responsible for tubulin affinity (Kaffy
et al., 2006).
COOH
substituted
unsubstituted
B
A
Results and discussion
Chemistry
Sixteen combretastatin analogs (1a–1p) were synthesized
by condensation of phenyl acetic acid (1) with different
substituted aldehydes (2) using triethyl amine and acetic
anhydride as reported previously (Cushman et al., 1995)
(Scheme 1). The products showed that the two phenyl rings
are cis to each other which is in tune with the classical
Pschorr reaction (The Merck Index, 2006) and it was fur-
ther confirmed by X-ray crystal analysis (Fig. 2). The
reaction was monitored by TLC. The compounds were
purified (yield 46–63%) by column chromatography using
silica gel #60–120 and characterized by spectral data (IR,
NMR, and MS). All compounds showed IR absorption
bands at around 3300–3400 for C–H str. 1680–1700 for
carbonyl, 1600 for C=C (phenyl) and about 1200 cm-1 for
C–O stretching. In 1H NMR proton at C-3 as a singlet is
With this background, we herein wish to report the
synthesis and anticancer activity of combretastatin analogs
of the following general structure:
OH
O
O
O
O
H3CO
H3CO
H3CO
H3CO
A
B
NHCOCH3
O
C
H3CO
OCH3
OH
OCH3
combretastatin A-4
H3CO
OCH3
OCH3
OCH3
podophyllotoxin
cholchicine
O
N
N
H3CO
H3CO
MeO
MeO
N
O
NH
NH
OCH3
OCH3
NH2
OCH3
OMe
azetidinone derivative
Cl
urea derivative
imidazole derivative
F
NH
N
O
O
H3CO
H3CO
H3CO
H3CO
S
OCH3
O
F
F
H3CO
NH2
OCH3
OCH3
sulfonate derivative
OH
OCH3
OCH3
trifluoroderivative
pyrazole derivative
Fig. 1 Combretastatin and its other synthetic analogs
123

3722
Med Chem Res (2012) 21:3720–3729
LogP (ClogP) values (Table 1) found no correlation,
indicating that the activity observed is not based on the
lipophilicity alone.
COOH
COOH
+
CHO
(A), (B)
reflux
R
R
Molecular docking
1
2
3
To get better interpretation of the observed activity of the
synthesized combretastatin analogs, a flexible docking
study of most potent compound 1b was performed on
colchicine-binding site of tubulin (PDB entry: 1SA0)
(Ravelli et al., 2004). All docking runs were performed
using GOLD software. To validate that the selected
docking procedure for the prediction of the correct binding
mode of ligands binding to the colchicine-binding site,
colchicine was extracted from the original X-ray structure
(1SA0) and re-docked using GOLD software (Gold et al.,
2009). The highest scoring conformation was selected and
compared with crystal structure with most stable confor-
mation. The docked conformation of colchicine using
GOLD was found to be similar to that found in the original
A, acetic anhydride; B, triethyl amine
R= different substitution/s
Scheme 1 Synthesis of combretastatin analogs
˚
X-ray structure (RMSD = 0.72 A between the best scored
conformers from docking and X-ray structure).
The GOLD scores and visual inspection allowed us to
select the most probable binding conformation of 1b
(Fig. 3). The docking study showed that 1b fits well at the
colchicine-binding site. The dimethoxy phenyl ring (ring
B) gets positioned in a hydrophobic cavity created by
Leu248b, Leu255b, and Val318b. Ring B of inhibitor
adopts similar orientation as the trimethoxy ring of col-
chicine in close proximity to Cys241b. The two methoxy
˚
groups at C2 and C3 are 5.2 and 3.8 A away from the
Cys241b, respectively. The three methoxy groups of col-
chicine also interact with the same residue. The methoxy
function at C-2 is involved in a hydrophobic interaction
with side chain of Ala250b (Fig. 3). The ring A gets
positioned in a hydrophobic cleft formed by Ala180a and
Val181a and oriented almost similar as ring C of colchi-
cine. The carbonyl function of carboxylic group of 1b is
involved in hydrogen bond interaction with free –NH2 of
Asn258b. The amino acid residue is seen in interaction
with OH of tropolone ring of colchicines and the
involvement of residue in hydrophobic cleft as well as in
hydrophilic region with involvement of H-bond are
important indication for the involvement of colchicines
binding site for this type of compounds.
Fig. 2 ORTEP derived from a single crystal X-ray analysis of 1m
(non-hydrogen atoms have been labeled using a crystallographic
numbering scheme)
highly deshielded because of being b to carbonyl with
d-value 7.8–8.2. Phenyl protons show signal around
7.2–7.7. 13C NMR carbonyl shows signal at around
165–170. Phenyl carbons show signals at around 115–132.
13C assignments have been corroborated by DEPT studies.
Biological (anticancer) activity
All compounds were evaluated for their anticancer activity
(Table 1) against human colon (colo-205), lung (A549),
ovary (IGROV-1), prostrate (PC-3), CNS (SF-295), leu-
kemia (THP-1), and breast (MCF-7) cell lines. Out of these
1a, 1b, 1c, 1k, 1n, and 1p showed anticancer activity
against colo-205 (colon), A-549 (lung), and MCF-7
(breast) cell lines. Compounds 1b and 1n showed marked
activity comparable to paclitaxel against lung cancer
cell line. A comparison of the cytotoxicity (IC50) of
compounds 1a–1p with their corresponding calculated
Conclusion
A series of combretastatin analogs have been synthesized
by condensation of phenyl acetic acid and different
substituted aldehydes. Structures were assigned with the
help of elemental analysis and spectral techniques like IR,
123

Med Chem Res (2012) 21:3720–3729
3723
Table 1 Anticancer activity data of compounds 1a–1p
Compound code
Conc. (mol)
% Growth inhibition
CLogPa
PC-3
Prostrate
IGR-OV-1
Ovary
SF-295
CNS
A-549
Lung
MCF-7
Breast
COLO-205
Colon
THP-1
Leukemia
1a
1b
1c
1d
1e
1f
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
5 9 10-5
1 9 10-4
1 9 10-6
1 9 10-5
1 9 10-5
2 9 10-5
0
4
0
0
14
25
8
52
54
60
89
21
65
0
29
41
25
52
54
63
32
39
14
24
–
–
–
–
–
3.59
3.25
2.89
3.55
2.77
3.24
3.33
4.04
3.60
2.89
4.76
4.30
4.30
4.30
2.92
2.32
2
6
–
–
4
11
0
24
13
25
15
38
0
–
–
10
22
11
39
12
23
4
–
–
1
–
–
0
–
–
32
8
45
0
–
–
–
–
17
–
12
–
20
0
–
–
5
0
28
10
22
0
–
–
20
15
25
10
43
0
–
16
32
60
15
44
0
21
0
1g
1h
1i
–
–
–
–
–
–
0
–
–
–
8
9
–
–
–
35
0
0
–
–
–
0
–
–
10
0
–
0
4
1j
0
–
–
–
0
0
7
–
–
0
–
0
0
1k
1l
26
35
36
52
30
68
14
42
53
60
31
74
–
–
–
0
–
51
70
–
0
–
–
0
–
22
–
32
42
0
–
12
14
32
40
61
74
10
20
52
82
–
5
–
10
0
–
–
1m
1n
1o
1p
–
–
–
38
0
–
0
–
–
–
10
22
6
–
–
0
–
–
–
6
–
–
–
18
15
31
–
–
20
14
26
77
65
–
–
–
–
–
–
–
–
–
Adriamycin
Mitomycin
Paclitaxel
87
–
–
–
58
–
–
–
–
–
66
–
–
67
–
–
–
5-Fluorouracil
–
–
–
74
69
IC50 of only active compounds 1a, 1b, 1c, 1k, 1n, and 1p were calculated on the basis of 5 different concentrations viz., 1 9 10-5, 3 9 10-5
,
5 9 10-5, 7 9 10-5, and 1 9 10-4 mol, found to be 85.4, 3.9, 88.0, [100, 34.0, and 96.5 lM, respectively
a
ClogP values were calculated using ChemDraw Ultra V.8.0 (Cambridge Soft Corporation)
MS, NMR (1H & 13C). All the synthesized compounds
were evaluated for anticancer activity against various cell
lines and some of them were found to be active. The
favorable binding conformation of 1b suggests its pre-
vailing role as microtubule polymerization inhibitors and
anticancer agents.
Experimental
The reagents were purchased from Sigma-Aldrich, Loba
and CDH, India and used without further purification. All
yields refer to isolated products after purification. Products
were characterized by comparison with authentic samples
123

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Med Chem Res (2012) 21:3720–3729
Fig. 3 a Overlay of colchicine (blue/dark) and 1b at the colchicine-binding site. b Docking conformation of 1b (Color figure online)
(Z)-3-(2,3-Dimethoxyphenyl)-2-phenyl-prop-2-enoic acid
(1b)
and by spectroscopic data (IR, 1H NMR, and 13C NMR
spectra). The spectra were measured in CDCl3 relative to
TMS (0.00 ppm). IR (KBr pallets) spectra were recorded
on a Fourier transform infrared (FT-IR) Thermo spectro-
photometer. Melting points were determined in open cap-
illaries and were found to be uncorrected.
M.p. 147–149; IR mmax cm-1 (KBr): 3418, 1672, 1638, 1260;
1HNMR (CDCl3) d: 3.8 (3H, s, H-200-OCH3), 3.9 (3H, s,
H-300-OCH3), 6.1 (1H, d, j = 7.7 Hz, Ar–H), 7.3–7.2 (5H, m,
5xAr–H), 8.2 (1H, s, H-3); 13C NMR (CDCl3): 52.6 (C-200-
OCH3), 53.8 (C-300-OCH3), 119.0, 121.0, 123.0, 128.4, 129.6,
130.0, 132.0, 133.9, 136.2, 138.0, 139.7, 140.0, 141.1, 146.1,
166.8;MS(ESI)m/z = 307 (M?Na)?;Anal.(C17H16O4)C,H.
General procedure for synthesis of compounds (1a–1p)
(Table 2)
(Z)-3-(3,4,5-Trimethoxyphenyl)-2-pheny-prop-2-enoic acid
(1c)
A mixture of phenyl acetic acid (7.36 mmol), different
substituted benzaldehydes (7.36 mmol) and triethylamine
(2 ml) in Ac2O (4 ml) was refluxed for 4–9 h. After com-
pletion of reaction (monitored by TLC), the reaction mixture
was cooled and acidified with 35% aqueous HCl (6 ml) and
kept at room temperature overnight. The precipitate was
collected by filtration and purified by column chromatogra-
phy using silica gel 60–120 and 30% ethyl acetate in hexane
as mobile phase to afford the pure product.
M.p. 182–184; IR mmax cm-1 (KBr): 3411, 1670, 1617,
1579, 1506, 1421; 1HNMR (CDCl3) d: 3.5 (6H, s, 2xAr-
OCH3), 3.8 (3H, s, Ar-OCH3), 6.3 (2H, s, Ar–H), 7.4–7.2
(5H, m, 5xAr0-H), 7.8 (1H, s, H-3); 13C NMR (CDCl3):
52.3, 53.0, 55.6, 121.1, 126.6, 128.0, 128.2, 128.9, 129.8,
142.2, 151.7, 152.6, 156.9, 159.7, 164.5, 174.8; MS (ESI)
m/z = 337 (M?Na)?; Anal. (C18H18O5) C, H.
Spectral analyses
(Z)-3-(3,4-Methylenedioxyphenyl)-2-phenyl-prop-2-enoic
acid (1d)
1
COOH
2"
2' 2
1'
6'
3
M.p. 188–189; IR mmax cm-1 (KBr): 3417, 1667, 1485,
1423, 1184, 1004; 1HNMR (CDCl3) d: 5.9 (2H, s,
-OCH2O–), 6.6 (3H, m, Ar00–H), 7.4–7.2 (5H, m, 5xAr0-
H), 7.8 (1H, s, H-3); 13C NMR (CDCl3): 101.6, 114.0,
119.0, 122.0, 132.4, 136.0, 166.6; MS (ESI) m/z = 291
(M?Na)?; Anal. (C16H12O4) C, H.
3'
4'
3"
4"
1"
6"
R
5'
5"
(Z)-2,3-Diphenyl-prop-2-enoic acid (1a)
M.p. 145–147°C; IR mmax cm-1 (KBr): 3450, 1674, 1615,
1269; 1HNMR (CDCl3) d; 7.3–7.0 (10H, m, 5xAr–H,
5xAr0–H), 7.95 (1H, s, H-3); 13C NMR (CDCl3):
116–128.7, 132.0, 143.7, 166.5; MS (ESI) m/z = 246.8
(M?Na)?; Anal. (C15H12O2) C, H.
(Z)-3-(3-Hydroxy-4-methoxypheny)-2-phenyl-prop-2-enoic
acid (1e)
M.p. 202–202; IR mmax cm-1 (KBr): 3511, 1670, 1607,
1459, 1267, 1135, 1005, 802, 709; 1HNMR (CDCl3)
123

Med Chem Res (2012) 21:3720–3729
3725
Table 2 Reaction time, yield, and elemental analysis data of the synthetics
HOOC
Ar
S. No.
Compound
code
Ar
Reaction
time (h)
% Yield
58
Elemental analysis (cal./found)
C
H
N
–
1
1a
1b
1c
1d
1e
1f
5
7
6
6
5
6
4
8
80.34/80.24
5.39/5.26
OCH3
H3CO
2
3
4
5
5
7
8
60
55
55
63
49
58
54
71.82/71.79
68.78/68.56
71.82/71.62
71.10/71.16
68.78/68.56
66.91/66.64
81.58/81.45
5.62/5.42
5.77/5.67
4.51/4.35
5.22/5.56
5.77/5.82
4.12/4.05
5.64/5.45
–
–
–
–
–
H3CO
H3CO
H3CO
O
O
HO
H3CO
OCH3
H3CO
H3CO
1g
1h
NO2
5.20/5.24
–
123

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Med Chem Res (2012) 21:3720–3729
Table 2 continued
S. No.
Compound
code
Ar
Reaction
time (h)
% Yield
59
Elemental analysis (cal./found)
C
H
N
–
OCH3
9
1i
6
7
9
5
6
7
6
6
71.82/71.79
5.62/5.22
H3CO
10
11
12
13
14
15
16
1j
58
53
56
54
60
48
46
68.78/68.56
83.19/83.34
69.64/69.61
69.64/69.51
69.64/69.51
72.33/72.23
70.31/70.34
5.77/5.67
5.14/5.11
4.29/4.46
4.29/4.42
4.29/4.42
5.0/5.12
–
–
–
–
–
–
–
OCH3
H3CO
H3CO
1k
1l
Cl
Cl
Cl
1m
1n
1o
1p
OH
HO
OH
4.72/4.75
d: 3.0 (Ar-OH), 3.7 (3H, s, Ar-OCH3), 6.5 (1H, s, Ar–H),
6.6 (1H, s, Ar0–H), 7.3–7.1 (6H, m, 1xAr00-H, 5xAr0-H),
7.7 (1H, s, H-3); 13C NMR (CDCl3): 43.7, 56.2,
113.2, 115.6, 120.0, 126.4, 128.0, 128.7, 132.6, 132.4,
166.5; MS (ESI) m/z = 315 (M?Na)?; Anal. (C16H14O4)
C, H.
123

Med Chem Res (2012) 21:3720–3729
3727
(Z)-3-(2,4,5-Trimethoxyphenyl)-2-phenyl-prop-2-enoic
acid (1f)
151.7, 152.6, 156.9, 159.7, 164.5, 174.5; MS (ESI)
m/z = 337 (M?Na)?; Anal. (C18H18O5) C, H.
M.p. 182–184; IR mmax cm-1 (KBr): 3477, 1668, 1603, 1506,
1264; 1HNMR (CDCl3) d: 3.18 (3H, s, Ar-OCH3), 3.87 (6H,
s, Ar-OCH3), 6.26 (H, s, Ar00–H), 6.43 (H, s, Ar00–H) 7.3–7.4
(5H, m, 5xAr0-H), 8.3 (1H, s, H-3); 13C NMR (CDCl3): 52.3,
53.0, 55.6, 121.1, 126.6, 128.0, 128.2, 128.9, 129.8, 142.2,
151.7, 152.6, 156.9, 159.7, 164.5, 174.8; MS (ESI)
m/z = 337 (M?Na)?; Anal. (C18H18O5) C, H.
(Z)-3-(Naphthalene-5yl)-2-phenyl-prop-2-enoic acid (1k)
M.p. 182–184; IR mmax cm-1 (KBr): 1677, 1614, 1579, 1506,
1260; 1HNMR (CDCl3) d: 7.4–7.2 (5H, m, Ar–H), 8.4–8.1
(7H, m, 5xAr0-H), 8.5 (1H, s, = CH); 13C NMR (CDCl3):
120, 123, 124.9, 125.3, 127.3, 127.9, 128.6, 129.3, 130,
130.4, 131.2, 131.5, 131.8, 133.5, 142.2, 146.3, 169.1; MS
(ESI) m/z = 297 (M?Na)?; Anal. (C19H14O2) C, H.
(Z)-3-(2-Nitrophenyl)-2-phenyl-prop-2-enoic acid (1g)
(Z)-3-(2-Chlorophenyl)-2-phenyl acrylic acid (1l)
M.p. 182–184; IR mmax cm-1 (KBr): 3411, 1670, 1617,
1579, 1506, 1421; 1HNMR (CDCl3) d: 6.3–6.9 (4H, m,
Ar00–H), 7.6–7.2 (5H, m, 5xAr0-H), 8.16 (1H, s, H-3); 13C
NMR (CDCl3): 123.3, 124.8, 126.6, 128.0, 128.3, 128.8,
129.1, 130.2, 130.5, 133.5, 140.4, 167.9; MS (ESI)
m/z = 292 (M?Na)?; Anal. (C15H11NO4) C, H, N.
M.p. 148–151; IR mmax cm-1 (KBr): 3421, 1663, 1619,
1589, 1516, 1411; 1HNMR (CDCl3) d: 7.0–6.8 (4H, m,
Ar00–H), 7.6–7.1 (5H, m, 5xAr0-H), 8.2 (1H, s, H-3); 13C
NMR (CDCl3): 120.3, 129.8, 126.6, 128.0, 128.3, 128.8,
129.1, 130.2, 130.5, 133.5, 140.4, 167.9; MS (ESI)
m/z = 281 (M?Na)?; Anal. (C15H11ClO2) C, H.
(2Z,4E)-2,5-Diphenylpenta-2,4-dienoic acid (1h)
(Z)-3-(3-Chlorophenyl)-2-phenyl-prop-2enoic acid (1m)
M.p. 182–184; IR mmax cm-1 (KBr): 3446, 1678, 1621, 1579,
1346; 1HNMR (CDCl3) d: 5.59 (1H, d, j = 15.2, = CH2),
5.96 (1H, dd, j = 15.2 & j = 14.8, = CH2), 6.8 (1H, d,
j = 15.2, = CH2), 7.4–7.2 (5H, m, 5xAr0-H), 7.7–7.5 (5H,
m, 5xAr0-H) 7.8 (1H, s, H-3); 13C NMR (CDCl3): 120.2,
122.1, 122.8, 123.0, 123.3, 124.2, 126.6, 128.0, 128.2, 128.9,
129.8, 135.5, 135.9, 144.2, 164.5; MS (ESI) m/z = 273
(M?Na)?; Anal. (C17H14O2) C, H.
M.p. 131–133; IR mmax cm-1 (KBr): 3421, 1663, 1619,
1589, 1516, 1411; 1HNMR (CDCl3) d: 7.0–6.8 (4H, m,
Ar00–H), 7.6–7.1 (5H, m, 5xAr0-H), 8.2 (1H, s, H-3); 13C
NMR (CDCl3): 120.3, 129.8, 126.6, 128.0, 128.3, 128.8,
129.1, 130.2, 130.5, 133.5, 140.4, 167.9; MS (ESI)
m/z = 281 (M?Na)?; Anal. (C15H11ClO2) C, H.
(Z)-3-(4-Chlorophenyl)-2-phenyl-prop-2enoic acid (1n)
M.p. 121–123; IR mmax cm-1 (KBr): 3451, 1643, 1624, 1585,
1516, 1421; 1HNMR (CDCl3) d: 6.4 (2H, d, J = 8.4, H-300 &
500)6.9 (2H, d, J = 8.4, H-200 & 600), 7.75–7.32 (5H, m, 5xAr0-
H), 7.89 (1H, s, H-3); 13C NMR (CDCl3): 119, 129.8, 126.6,
128.0, 128.3, 129.8, 126.6, 130.8, 130.5, 133.5, 145.4, 168.5;
MS (ESI) m/z = 281 (M?Na)?; Anal. (C15H11ClO2) C, H.
(Z)-3-(2,5-Dimethoxyphenyl)-2-phenyl-prop-2-enoic acid
(1i)
M.p. 147–149; IR mmax cm-1 (KBr): 3437, 1666, 1580,
1260; 1HNMR (CDCl3) d: 3.2 (3H, s, OCH3), 3.9 (3H, s,
–OCH3), 6.2 (1H, d, j = 7.9 Hz, Ar–H), 6.75 (1H, d,
j = 7.9 Hz, Ar–H) 7.3–7.2 (5H, m, Ar0–H), 8.3 (1H, s,
H-3); 13C NMR (CDCl3): 50.6, 54.3, 119.0, 121.0, 125.0,
127.5, 129.6, 130.0, 132.0, 133.8, 135.2, 138, 139.7, 139.0,
145.1, 146.7, 167.6; MS (ESI) m/z = 307 (M?Na)?; Anal.
(C17H16O4) C, H.
(Z)-3-(2-Acetoxyphenyl)-2-phenyl-prop-2enoic acid (1o)
M.p. 178–180; IR mmax cm-1 (KBr): 3396, 1643, 1589,
1411; 1HNMR (CDCl3) d: 3.47 (3H, S, OCOCH3) 7.8–7.6
(4H, m, Ar00–H), 7.5–7.3 (5H, m, 5xAr0-H), 8.26 (1H, s,
H-3); 13C NMR (CDCl3): 123.3, 129.8, 126.6, 128.0,
128.3, 124.8, 129.1, 130.2, 132.5, 133.5, 140, 167.1; MS
(ESI) m/z = 305 (M?Na)?; Anal. (C17H14O4) C, H.
(Z)-3-(2,3,4-Trimethoxyphenyl)-2-pheny-prop-2enoic acid
(1j)
M.p. 182–184; IR mmax cm-1 (KBr): 3411, 1667, 1491,
1258; 1HNMR (CDCl3) d: 3.7 (3H, s, Ar-OCH3), 3.8 (3H,
s, Ar-OCH3), 3.9 (3H, s, Ar-OCH3), 6.3 (1H, d, j = 8.8,
Ar00–H), 6.4 (1H, d, j = 8.8, Ar00–H), 7.4–7.2 (5H, m,
Ar0–H), 8.2 (1H, s, H-3); 13C NMR (CDCl3): 52.9, 53.8,
55.6, 121.1, 126.6, 128.0, 128.2, 128.9, 129.8, 140.2,
(Z)-3-(2,3-Dihydroxyphenyl)-2-phenyl-prop-2enoic acid
(1p)
M.p. 191–192; IR mmax cm-1 (KBr): 3475, 3354, 1633,
1589, 1411; 1HNMR (CDCl3) d: 3.77 (2H, S, OH, D2O
123

3728
Med Chem Res (2012) 21:3720–3729
exchangeable) 7.2–7.0 (3H, m, Ar00–H), 7.5–7.3 (5H,
m, 5xAr0-H), 8.21 (1H, s, H-3); 13C NMR (CDCl3):
123.3, 126.6, 128.0, 128.8, 124.8, 129.1, 130.2, 132.5,
133.5, 136.0, 166.0; MS (ESI) m/z = 266 (M?Na)?; Anal.
(C17H14O4) C, H.
percent growth inhibition in the presence of test material
was calculated. IC50 of only active compounds were
calculated on the basis of 5 different concentrations
viz., 1 9 10-5, 3 9 10-5, 5 9 10-5, 7 9 10-5, and 1 9
10-4 mol.
Acknowledgments The authors are grateful to ISF College of
Pharmacy, Moga for providing research facilities; IIIM, Jammu for
spectral analysis as well pharmacological activity and to Prof.
Rajnikant and Dr. Vivek Gupta, University of Jammu, Jammu Tawi,
for X-ray crystal analysis.
Materials and methods of docking study
The coordinates of colchicine were obtained from protein
data bank (PDB entry: 1sa0) (Ravelli et al., 2004). The
structure of 1b was drawn in ChemDraw and subjected to
energy minimization in the MOPAC module, using the AM1
procedure for closed shell systems, implemented in the CS
Chem3D Ultra (ChemDraw Ultra 6.0, 2000). The ligands
were docked at the colchicine-binding site of tubulin using
the GOLD 4.0.1 (Gold et al., 2009). Gold performs genetic
algorithm based ligand docking to optimize the conforma-
tion of ligand at the receptor binding site. It utilizes Gold
Score fitness function to evaluate the various conformations
of ligand at the binding site and comprises of four compo-
nents: protein–ligand hydrogen bond energy, protein–ligand
van der Waals (vdw) energy, ligand internal vdw energy, and
ligand torsional strain energy.
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