Structure-activity relationship study of growth inhibitory 2-styrylchromones against carcinoma cells

Article abstract of DOI:10.1007/s00044-012-0232-6

The structure-activity relationship study of 2-styrylchromones against carcinoma cell growth is discussed in the present report. Taking advantage of 2-styrylchromone as a molecular template, a series of structural modifications was carried out and examined on several carcinoma cell lines. Interestingly, AGS cells exhibited more sensitivity in response to methoxy-bearing compounds, of which compound 23 (3,4,5-trimethoxy group on ring B) showed the most potent activity with a GI₅₀ value of 1.3 μM. Surprisingly, as methoxy groups in 12 and 24-27 were demethylated to generate their hydroxyl counterparts 28-32, none of them displayed appreciable activity against all carcinoma cells. We further confirmed the pivotal role of rigidity for growth inhibitory activity between the rigid 12 and its flexible counterpart 33. Taken together, in the present report, we have clearly demonstrated the structure-activity relationship study of 2-styrylchromones targeting carcinoma cell growth.

Full text of DOI:10.1007/s00044-012-0232-6

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2013) 22:2385–2394
DOI 10.1007/s00044-012-0232-6
ORIGINAL RESEARCH
Structure–activity relationship study of growth inhibitory
2-styrylchromones against carcinoma cells
•
Chen Lin Pei-Jung Lu Chia-Ning Yang
•
•
•
Christopher Hulme Arthur Y. Shaw
Received: 5 April 2012 / Accepted: 11 September 2012 / Published online: 23 September 2012
Ó Springer Science+Business Media, LLC 2012
Abstract The structure–activity relationship study of
2-styrylchromones against carcinoma cell growth is dis-
cussed in the present report. Taking advantage of 2-sty-
rylchromone as a molecular template, a series of structural
modifications was carried out and examined on several car-
cinoma cell lines. Interestingly, AGS cells exhibited more
sensitivity in response to methoxy-bearing compounds, of
which compound 23 (3,4,5-trimethoxy group on ring B)
showed the most potent activity with a GI50 value of 1.3 lM.
Surprisingly, as methoxy groups in 12 and 24–27 were
demethylated to generate their hydroxyl counterparts 28–32,
none of them displayed appreciable activity against all car-
cinoma cells. We further confirmed the pivotal role of
rigidity for growth inhibitory activity between the rigid 12
and its flexible counterpart 33. Taken together, in the present
report, we have clearly demonstrated the structure–activity
relationship study of 2-styrylchromones targeting carcinoma
cell growth.
Keywords Structure–activity relationship study ꢀ
2-Styrylchromone ꢀ Carcinoma cells ꢀ Growth inhibition
Introduction
Regardless of the availability of computer-assisted strate-
gies toward drug discovery programs, drug-like core
structures stemmed from natural products are still highly
demanded due to their structural novelty and biologic rel-
evance. It can be agreed that abundant clinically used drugs
either mimic naturally occurring molecules or bear scaf-
folds that are fully or partially employed from natural
products (Balunas and Kinghorn, 2005). For instance, the
phase 2 clinical trial candidate flavopiridol (Kelland, 2000;
Senderowicz and Sausville, 2000), bearing a chromone (1)
core structure, is a cyclin-dependent kinase (CDK) inhib-
itor derived from the indigenous Indian plant Dysoxylum
binectariferum (Fig. 1). This chromone (1) core structure is
found in flavone (2), isoflavone (3), and 2-styrylchromone
(4), of which are ubiquitously distributed in several species
of higher plants (Fig. 1). It is noteworthy that 2-styrylchr-
omones (4) are a small group of chromone derivatives
specifically recognized by a styryl group appended at
2-position of the chromone (1) core structure.
C. Lin
Department of Chemistry, Tamkang University, New Taipei City
251, Taiwan
P.-J. Lu
Institute of Clinical Medicine, National Cheng Kung University,
Tainan 701, Taiwan
C.-N. Yang
Institute of Biotechnology, National University of Kaohsiung,
Kaohsiung 811, Taiwan
Naturally occurring homothamnione, 6-desmethoxyhom-
othamnione, and 5-hydroxy-2-styrylchromone have been
characterized for antitumor and neuroprotective activities
(Gerwick et al., 1986; Gerwick, 1989). Interestingly, several
2-styrylchromone derivatives have been synthesized before
the isolation of first natural compounds. 2-Styrylchromones
possess a broad spectrum of biologic activities, including
C. Hulme ꢀ A. Y. Shaw (&)
BIO5 Oro Valley, University of Arizona, 1580 E. Hanley Blvd.,
Oro Valley, AZ 85737, USA
e-mail: shaw@pharmacy.arizona.edu
C. Hulme ꢀ A. Y. Shaw
Department of Pharmacology and Toxicology, College of
Pharmacy, The University of Arizona, Tucson, AZ 85721, USA
123

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Med Chem Res (2013) 22:2385–2394
O
O
OH
O
Cl
O
O
O
5
8
4
7
6
3
2
HO
HO
O
O
1
O
O
N
Flavopiridol
Fig. 1 Schematic representation of flavopiridol, chromones (1), flavones (2), isoflavones (3), and 2-styrylchromones (4)
chromone (1)
2-styrylchromone (4)
isoflavone (3)
flavone (2)
anti-allergic (Doria et al., 1979), antitumor (Momoi et al.,
2005; Marinho et al., 2008), antiviral (Desideri et al., 2000;
Desideri et al., 2003; Conti et al., 2005), antioxidant (Filipe
et al., 2004; Gomes et al., 2007), anti-inflammatory (Gomes
et al., 2009), and to serve as antagonists of A3 adenosine
receptor (Karton et al., 1996), inhibitors of xanthine oxidase
(Fernandes et al., 2002). Recently, we embarked on the
synthesis of 2-styrylchromones with aim to examine their
antiproliferative effect on human carcinoma cell lines. Our
results indicated that the exposure of HeLa cells to 2-styrylchr-
omones lead to significant G1 phase cell cycle arrest, DNA
fragmentation, and programed cell death (Shaw et al., 2009).
To continue our effort on the elucidation of carcinoma cells
in response to 2-styrylchromones, herein, we report the
synthesis of some newly synthesized 2-styrylchromones
aimed at examining the structure–activity relationship of
growth inhibition of carcinoma cell lines.
including AGS (gastric carcinoma cell), HeLa (cervical epithe-
lioid carcinoma cell), OVCA (ovarian carcinoma cell), SKHep
(hepatocellular carcinoma cell), H460 (large lung carcinoma
cell), PC-3 (prostate carcinoma cell), SW620 (colorectal ade-
nocarcinoma cell), and BT483 (mammary gland adenocarci-
noma cell). We employed the MTT (3-[4,5-dimethylthiazol-2-
yl]-2,5-diphenyltetrazolium bromide) assay to study the growth
inhibition. The compound concentration causing 50 % cell
growth inhibition (GI50) was determined by interpolation from
dose–response curves.
As shown in Table 1, modifications of 2-styrylchromones
on ring B revealed some interesting structure–activity correla-
tions. For example, compared to their counterpart of
unsubstituted 6, upon the introduction of methoxy groups to
generate compounds 7–12, 9 (4-OMe) and 12 (3,4,5-tri-OMe)
exhibited significant improvement in potency against AGS
cells with GI50 values of 8 and 2 lM, respectively. Similarly, 9
(4-OMe, GI50, 7 lM), 8 (3-OMe, GI50, 17 lM) and 12 (3,4,5-
tri-OMe, GI50, 6 lM) displayed potent activity, while 7
(2-OMe, GI50,[40 lM), 10 (3,5-di-OMe, GI50,[40 lM) and
11 (3,4-di-OMe, GI50,[40 lM) resulted in the loss of activity
against HeLa cells. On the other hand, only 9 (4-OMe) and 12
(3,4,5-tri-OMe) showed appreciable improvement in potency
against OVCA cells with GI50 values of 6 and 8 lM, respec-
tively. Interestingly, both mono-substituted 8 (3-OMe, GI50,
8 lM)and 9 (4-OMe, GI50,5 lM) exhibited more potency than
that of tri-substituted 12 (3,4,5-tri-OMe, GI50, 14 lM) against
SKHep cells. Except for 7 and 11, without any activity, 8, 9, 10,
and 12 displayed dramatically improved activity against H460
cells with GI50 values of 16, 7, 25, and 6 lM, respectively.
Meanwhile, benzene ring was replaced with pyridine ring to
generate 14 (4-pyridyl) and 15 (3-pyridyl). Surprisingly, only
14 showed more potency against a panel of five cell lines
against HeLa, OVCA, and SKHep cells with GI50 values of
24, 10, and 15 lM, respectively. This discrepancy in activity
might be attributed to the preferred interactions between
molecular targets and 14 for favored hydrogen bond inter-
action. Compared to its counterpart 6, 16 bearing 4-N,
N-dimethylamino group on ring B exhibited more potent
activity against AGS, OVCA, and H460 cells with GI50
values of 9, 10, and 8 lM, respectively. As the benzene ring
was introduced with strong electron-withdrawing groups
such as 3,4-di-fluoro group in 18, a remarkable improvement
Results and discussion
Chemistry
As shown in Fig. 2, a series of 2-styrylchromones and their
modifications was carried out in a systematic manner. In
Route A, we incorporated various substituents on the ring B to
give 6–22 (Fig. 3, Scheme 1). The structural modifications in
Route B were mainly originated from the results of Route A.
Accordingly, ring A modification of 2-styrylchromone scaf-
fold was carried out in which the 3,4,5-trimethoxy groups on
ring B were maintained, such that analogs 23–27 were syn-
thesized (Fig. 3, Scheme 1). In Route C, methoxy groups in
23–27 were completely removed via boron tribromide
(BBr3)-mediated demethylation to yield the corresponding
polyphenol analogs28–32 (Fig. 3, Scheme 2). InRouteD, we
examined whether the styryl group in compound 12 is
essential for the activity by which hydrogenation was carried
out to generate the corresponding 33 (Fig. 3, Scheme 3).
Growth inhibition
In this study, growth inhibition of 2-styrylchromones was
examined in vitro against a panel of human carcinoma cell lines,
123

Med Chem Res (2013) 22:2385–2394
2387
Fig. 2 Overall synthetic routes
of structure–activity
O
O
O
relationship study of
2-styrylchromones
A
Route C
OMe
Route A
O
O
O
33
Ar
B
4
6-22
OMe
Route B
O
OMe
O
O
HO
Route D
MeO
O
OH
OH
OMe
OMe
23-27
28-32
OH
OMe
analogs 22–27 were synthesized and evaluated for their
growth inhibition. To our surprise, except for 23 (5-OMe)
which showed improved activity with a GI50 value of 1.3 lM
against AGS cells, all analogs exhibited decreased potency
with GI50 values between 10 and 24 lM as indicated in
Table 2. Both 24 (6-OMe) and 26 (5,7-di-OMe) displayed
equal potency against H460 cells with GI50 values of 10 lM,
which is less active than that of counterpart 22 (GI50, 6 lM).
Moreover, as polymethoxy analogs were removed in Route
D to obtain polyphenols 28–32, the activity completely
disappeared. These findings might be attributable to the
alternation of physical properties, particularly loss of
hydrophobicity for appropriate cell membrane penetration.
To examine whether the rigidity in 2-styrylchrome skeleton
plays a role for the activity, the double bond of styryl group in
analogs 12 was subjected to undergo hydrogenation which
afforded the corresponding product 33. Interestingly, the
activity of 33 was dramatically decreased in comparison to its
counterpart 12 as indicated in Table 3. Among seven cell lines,
only BT483, OVCA, and SKHep showed moderate activity in
response to 33 treatment with GI50 values of 21, 24, and 19 lM,
respectively. This finding clearly suggested that a certain level
of rigidity in the structure plays an important role for activity.
Scheme 1
O
O
R
NaOMe/MeOH
aldehydes
R
O
O
6-27
5
R
Scheme 2
O
O
R
BBr3/DCM
-40 oC to rt
R
O
O
OH
OMe
R = OH 28-32
R = OMe 23-27
OH
OMe
OH
OMe
Scheme 3
O
O
H2, Pd/C
O
MeOH
OCH3
O
OCH3
OCH3
12
33
OCH3
OCH3
OCH3
Fig. 3 Synthetic schemes employed for the structure–activity rela-
tionship of 2-styrylchromones
Conclusion
in activity against AGS, HeLa, SKHep, and H469 cells was
found with GI50 values of 15, 9.9, 9, and 18 lM, respec-
tively. According to data shown in Table 1, all five carci-
noma cell lines exhibited higher sensitivity in response to
electron-withdrawing substituents on ring B with moderate
activity.
In conclusion, we have demonstrated that modifications of
ring B exhibited certain degree of significant structure–
activity relationships than that of ring A. Particularly, AGS
cells showed more sensitivity to the tested compounds, in
which compound 23 bearing polymethoxy group exhibited
the most potent activity with a GI50 value of 1.3 lM. As
methoxy groups in 12 and 24–27 were removed to the
counterpart 28–32 with hydroxyl groups, none of them dis-
played appreciable activity against all carcinoma cells.
Moreover, we further demonstrated that the vinyl group is
We further focused on the ring A structural modifications
of 2-styrylchromone scaffold in which ring B remained
3,4,5-trimethoxy groups owing to 12 with the most potent
activity against AGS cells. As a consequence, polymethoxy
123

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Med Chem Res (2013) 22:2385–2394
Table 1 Growth inhibition of 2-styrylchromones 6–22 against carcinoma cells
O
O
Ar
6-22
No.
Ar
GI50 (lM)a
AGS
HeLa
OVCA
SKHep
H460
6
Ph
[40
[40
[40
25
2
1
21
2
3
[40
[40
[40
[40
16
7
2-OMe–Ph
3-OMe–Ph
4-OMe–Ph
3,5-Di-OMe–Ph
3,4-Di-OMe–Ph
3,4,5-Tri-OMe–Ph
2-Benzo[d][1,3]dioxol-5-yl
4-Pyridyl
[40
17
[40
21
8
8
1
1
3
4
9
8
0.4
0.2
7
1
6
1
3
5
7
2
10
[40
[40
2
[40
[40
6
[40
27
21
2
2
3
25
11
2
1
[40
14
[40
6
12
1
8
1
13
[40
[40
[40
9
14
1
2
1
2
4
[40
10
[40
15
[40
[40
[40
8
14
24
15
3-Pyridyl
16
[40
10
[40
[40
22
16
4-NMe2–Ph
4-Br–Ph
1
1
3
1
24
1
1
2
1
2
17
[40
15
24
23
2
17
3
4
3
4
5
3
18
3,4-Di-F–Ph
4-Cl–Ph
9.9
[40
29
1
23
9
1
2
18
19
[40
25
11
9
22
20
4-CF3–Ph
6
2
[40
[40
[40
14
4
1
19
21
4-OCF3–Ph
4-NO2–Ph
[40
14
16
[40
10
21
22
8
1
16
Doxorubicin
0.02 0.01
0.33 0.04
0.95 0.07
0.09 0.03
0.11 0.02
a
GI50 values are presented as the Mean SEM (standard error of the mean) from four to six separated experiments
(E)-2-Styryl-4H-chromen-4-one (6)
pivotal for activity since 33 with a rotatable single bond
between the chromone core structure and ring B significantly
decreased growth inhibitory activity. Taken together, we
have successfully synthesized a series of 2-styrylchromone
derivatives and examined their growth inhibition activity
against a panel of carcinoma cell lines for further study.
Sodium (0.69 g, 30.0 mmol) was gradually added to dry
methanol (30 ml) and the mixture was stirred until the
solution reached room temperature. 5 (0.73 g, 5.0 mmol)
and benzaldehyde (0.64 g, 6.0 mmol) were added and the
resulting mixture was allowed to stir at reflux for 18 h. After
this period, the solution was poured into iced water and the
pH was adjusted to 4 with aqueous HCl. The yellow solid was
removed by filtration, taken up in DCM, and purified with
silica gel chromatography (eluent, DCM: ethyl ace-
tate = 4:1) to give 6 (0.93 g, 75 %) as a white solid. Mp
134 °C (lit. (Silva et al., 1998) 131–133 °C). 1H NMR
(300 MHz, CDCl3) d 6.31 (s, 1H), 6.76 (d, J = 16.0 Hz,
1H), 7.43–7.34 (m, 4H), 7.58–7.50 (m, 3H), 7.59 (d,
J = 16.0 Hz, 1H), 7.66 (dd, J = 8.7, 7.2 Hz, 1H), 8.18 (d,
J = 7.9 Hz, 1H) ppm. 13C NMR (75 MHz, CDCl3) d 110.8,
118.0, 120.4, 124.3, 125.1, 125.8, 127.8, 129.1, 130.0, 133.8,
135.1, 137.1, 156.2, 161.9, 178.5 ppm. HRMS (M)? calcd.
for C17H12O2 248.0837; found 248.0834.
Experimental
Chemistry
Chemical reagents and organic solvents were purchased from
TCI and Alfa Aesar unless otherwise mentioned. Melting
points were determined by Fargo MP-2D. Nuclear magnetic
resonance spectra (1H NMR) were measured on a Bruker
AC-300 instrument. Chemical shifts (d) are reported in parts
per million relative to the TMS peak. Mass spectra were
obtained byFAB ona JeolJMS-700 instrument. Flashcolumn
chromatography was performed with silica gel (230–400 mesh).
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Med Chem Res (2013) 22:2385–2394
2389
(E)-2-(2-Methoxystyryl)-4H-chromen-4-one (7)
Table 2 Growth inhibition of 2-styrylchromones 23–32 against car-
cinoma cells
Compound 7 was synthesized from the procedure described
for compound 6
O
O
5
8
4
5
8
4
3
6
R
7
3
6
R
7
2
2
1
O
1
O
Yield 57.8 %. Mp 118.2 °C. H NMR (300 MHz, CDCl3)
1
OH
OH
OMe
OMe
d 3.92 (s, 3H), 6.31 (s, 1H), 6.85 (d, J = 16.1 Hz, 1H),
6.93 (d, J = 7.9 Hz, 1H), 6.98 (dd, J = 7.6, 7.5 Hz, 1H),
7.32 (dd, J = 7.6, 7.9 Hz, 1H), 7.37 (dd, J = 7.9, 7.0 Hz,
1H), 7.53 (d, J = 8.4 Hz, 1H), 7.56 (d, J = 7.5 Hz, 1H),
7.65 (dd, J = 7.0, 8.4 Hz, 1H), 7.90 (d, J = 16.1 Hz, 1H),
8.18 (d, J = 7.9 Hz, 1H) ppm. 13C NMR (75 MHz,
CDCl3) d 55.7, 110.4, 111.3, 118.1, 120.9, 121.0, 124.1,
124.3, 125.0, 125.7, 128.3, 131.2, 132.5, 133.6, 156.2,
158.1, 162.6, 178.6 ppm. HRMS (M?1)? calcd. for
C18H14O3 279.0976; found 279.1019.
28-32
23-27
OH
OMe
No. R
GI50 (lM)a
AGS
PC-3
H460
SW620
23 5-OMe 1.3 0.07 20
4
5
[40
10
17
26
3
3
24 6-OMe 10
25 7-OMe 12
1
1
29
2
2
[40
[40
[40
10
[40
27
26 5,7-Di- 10 0.2
OMe
4
(E)-2-(3-Methoxystyryl)-4H-chromen-4-one (8)
27 7,8-Di- 24
OMe
2
[40
[40
[40
Compound 8 was synthesized from the procedure described
for compound 6
28
H
[40
[40
[40
[40
[40
[40
[40
[40
[40
[40
[40
[40
[40
29 6-OH [40
30 7-OH [40
Yield 42.8 %. Mp 139.9 °C. 1H NMR (300 MHz, CDCl3)d
3.87(s, 3 H), 6.33 (s, 1 H), 6.77 (d, J = 16.0 Hz, 1H), 6.95
(dd, J = 7.9, 7.7 Hz, 1H), 7.10 (s, 1H), 7.18 (d, J = 7.7 Hz,
1H), 7.32 (d, J = 7.9 Hz, 1H), 7.39 (dd, J = 7.9, 7.4 Hz,
1H), 7.53 (d, J = 7.8 Hz, 1H), 7.58 (d, J = 16.0 Hz, 1H),
7.68 (dd, J = 7.8, 7.4 Hz, 1H), 8.18(d, J = 7.9 Hz,
1H) ppm. 13C NMR (75 MHz, CDCl3) d 55.5, 110.9, 112.9,
115.8, 118.0, 120.5, 120.7, 124.3, 125.1, 125.8, 130.1, 133.9,
136.5, 137.0, 156.2, 160.2, 161.8, 178.5 ppm. HRMS
(M?1)? calcd. for C18H14O3 279.0976; found 279.1017.
31 5,7-Di- [40
OH
32 7,8-Di- [40
OH
[40
[40
[40
Doxorubicin 0.02 0.01 1.76 0.71 0.11 0.02 0.03 0.005
a
GI50 values are presented as the Mean SEM (standard error of
the mean) from four to six separated experiments
Table 3 Comparison of 12 with its counterpart 33 in regard to their
growth inhibition against carcinoma cells
O
O
O
O
(E)-2-(4-Methoxystyryl)-4H-chromen-4-one (9)
Compound 9 was synthesized from the procedure described
for compound 6
OCH3
OCH3
OCH3
OCH3
12
33
Yield 43.9 %. Mp 140.3 °C (lit. (Makrandi and Kumari, 1989)
137–139 °C). 1H NMR (300 MHz, CDCl3) d 3.86(s, 3H), 6.29
(s, 1H), 6.65 (d, J = 16.0 Hz, 1H), 6.94 (d, J = 7.0 Hz, 2H),
7.38 (dd, J = 7.5, 7.6 Hz, 1H), 7.52 (d, J = 7.7 Hz, 1H), 7.54
(d, J = 7.0 Hz, 1H), 7.57 (d, J = 16.0 Hz, 1H), 7.67 (dd,
J = 7.7, 7.7 Hz, 1H), 8.20(d, J = 7.6 Hz, 1H) ppm. 13CNMR
(75 MHz, CDCl3) d 55.5, 110.9, 112.8, 115.7, 118.0, 120.5,
120.7,124.2, 125.1, 125.8, 130.1, 133.9, 136.5, 137.0, 156.1,
160.1, 161.7, 178.6 ppm. HRMS (M?1)? calcd. for C18H14O3
279.0976; found 279.1014.
OCH3
OCH3
No. GI50 (lM)a
AGS
2
BT483 HeLa OVCA SKHep H460 SW620
12
0.2 10
21
2
4
6
1
8
3
14
19
2
1
6
1
8
0.2
33 [40
[40
24
4
[40
[40
a
GI50 values are presented as the Mean SEM (standard error of
the mean) from four to six separated experiments
123

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Med Chem Res (2013) 22:2385–2394
(E)-2-(3,5-Dimethoxystyryl)-4H-chromen-4-one (10)
(s, 1H), 6.98 (d, J = 8.0 Hz, 1H), 7.07 (d, J = 16.1 Hz, 2H),
7.20 (d, J = 8.0 Hz, 1H), 7.39 (d, J = 1.28 Hz, 1H), 7.45 (dd,
J = 7.0, 7.8 Hz, 1H), 7.61(d, J = 16.1 Hz, 1H), 7.67(d,
J = 8.5 Hz, 1H), 7.80 (dd, J = 8.5, 7.0 Hz, 1H), 7.99 (d,
J = 7.8 Hz, 1H) ppm. 13C NMR (75 MHz, CDCl3) d 101.8,
106.3, 108.8, 110.3, 118.0, 118.5, 124.1, 124.3, 125.1, 125.9,
129.7, 133.8, 136.8, 148.7, 149.5, 156.2, 162.2, 178.6 ppm.
HRMS (M?1)? calcd. for C18H12O4 293.0769; found 293.0809.
Compound 10 was synthesized from the procedure
described for compound 6
Yield 45.3 %. Mp 152.9 °C. 1H NMR (300 MHz, CDCl3) d
3.83 s, 6H), 6.31 (s, 1H), 6.48 (t, J = 2.1, 2.3 Hz, 1H), 6.70
(s, 2H), 6.73 (d, J = 15.9 Hz, 1H), 7.37 (dd, J = 8.0,
7.0 Hz, 1H), 7.51 (d, J = 8.7 Hz, 1H), 7.52 (d, J = 15.9 Hz,
1H), 7.66 (dd, J = 8.7, 7.0 Hz, 1H), 8.17 (d, J = 8.0 Hz,
1H) ppm. 13C NMR (75 MHz, CDCl3) d 55.5, 102.1, 105.7,
110.8, 117.9, 120.7, 124.1, 125.1, 125.7, 133.8, 136.9, 137.0,
156.1, 161.2, 161.7, 178.5 ppm. HRMS (M?1)? calcd. for
C19H16O4 309.1082; found 309.1124.
(E)-2-(2-(Pyridin-4-yl)vinyl)-4H-dchromen-4-one (14)
Compound 14 was synthesized from the procedure
described for compound 6
Yield 35.7 %. Mp 179.7 °C. 1H NMR (300 MHz, CDCl3) d
6.38 (s, 1H), 6.95 (d, J = 16.0 Hz, 1H), 7.37–7.43 (m, 3H),
7.51 (d, J = 16.0 Hz, 1H), 7.53 (d, J = 8.6 Hz, 1H), 7.69
(dd, J = 8.6, 7.0 Hz, 1H), 8.18 (d, J = 7.9 Hz, 1H), 8.66
(d, J = 6.0 Hz, 2H) ppm. 13C NMR (75 MHz, CDCl3) d
112.2, 117.9, 118.1, 121.6, 124.2, 124.9, 125.4, 125.9,
133.8, 134.1, 142.3, 150.7, 156.1, 160.5, 178.5 ppm. HRMS
(M?1)? calcd. for C16H11NO2 250.0823; found 250.0867.
(E)-2-(3,4-Dimethoxystyryl)-4H-chromen-4-one (11)
Compound 11 was synthesized from the procedure
described for compound 6
Yield 30.2 %. Mp 166.1 °C (lit. (Cheema et al., 1932) 165 °C).
1H NMR (300 MHz, CDCl3) d 3.92 (d, J = 11.0 Hz, 6H), 6.28
(s, 1H), 6.62 (d, J = 15.9 Hz, 1H), 6.87 (d, J = 8.2 Hz, 1H),
7.08 (s, 1H), 7.14 (d, J = 8.2 Hz, 1H), 7.35 (dd, J = 7.4,
7.7 Hz, 1H), 7.49 (d, J = 8.0 Hz, 1H), 7.53 (d, J = 15.9 Hz,
1H), 7.64 (dd, J = 7.4, 8.0 Hz, 1H), 8.16 (d, J = 7.7 Hz,
1H) ppm. 13C NMR (75 MHz, CDCl3) d 56.1, 109.6, 110.1,
111.4, 117.9, 118.2, 122.2, 124.3, 125.1, 125.8, 128.2, 133.7,
137.0, 149.5, 151.1, 156.2, 162.3, 178.5 ppm. HRMS (M?1)?
calcd. for C19H16O4 309.1082; found 309.1137.
(E)-2-(2-(Pyridin-3-yl)vinyl)-4H-chromen-4-one(15)
Compound 15 was synthesized from the procedure
described for compound 6
Yield 32.2 %. Mp 175.9 °C. 1H NMR (300 MHz, CDCl3) d
6.35 (s, 1H), 6.85 (d, J = 16.1 Hz, 1H), 7.33–7.37 (m, 1H),
7.39(dd, J = 6.9, 7.9 Hz, 1H), 7.54(d, J = 8.6 Hz, 1H), 7.59
(d, J = 16.1 Hz, 1H), 7.69 (dd, J = 8.6, 6.9 Hz, 1H), 7.91 (d,
J = 8.0 Hz, 1H), 8.18 (d, J = 7.9 Hz, 1H), 8.59 (d,
J = 4.8 Hz, 1H), 8.79 (d, J = 2.0 Hz, 1H) ppm. 13C NMR
(75 MHz, CDCl3) d 111.4, 117.9, 122.4, 123.9, 124.1, 125.2,
125.7, 130.8, 133.1, 133.6, 134.1, 149.6, 150.5, 156.0, 160.9,
178.5 ppm. HRMS (M?1)? calcd. for C16H11NO2 250.0823;
found 250.0866.
(E)-2-(3,4,5-Trimethoxystyryl)-4H-chromen-4-one (12)
Compound 12 was synthesized from the procedure
described for compound 6
Yield 70 %. Mp211.2 °C. 1H NMR (300 MHz, CDCl3)d3.92d,
J = 11.5 Hz, 9H), 6.32 (s, 1H), 6.68 (d, J = 16.0 Hz, 1H), 6.80
(s,2H),7.39(dd,J = 9.0, 7.9 Hz, 1H), 7.52 (s, J = 7.7 Hz, 1H),
7.53 (d, J = 16.0 Hz, 1H), 7.67 (dd, J = 9.0, 7.7 Hz, 1H), 8.19
(d, J = 7.9 Hz, 1H) ppm. 13C NMR (75 MHz, CDCl3) d 56.2,
56.3, 61.1, 105.1, 110.5, 117.9, 119.6, 124.2, 125.1, 125.8, 130.7,
133.8, 137.0, 140.1, 153.7, 156.1, 161.8, 178.4 ppm. HRMS
(M)? calcd. for C20H18O5 338.1154; found 338.1151.
(E)-2-(4-(Dimethylamino)styryl)-4H-chromen-4-one
(16)
Compound 16 was synthesized from the procedure
described for compound 6
fYield 48.3 %. Mp 120.2 °C. 1H NMR (300 MHz, CDCl3)
d 3.02 (s, 6H), 6.25 (s, 1H), 6.56 (d, J = 15.9 Hz, 1H),
6.70 (d, J = 8.9 Hz, 2H), 7.36 (dd, J = 8.0, 6.8 Hz, 1H),
7.48 (d, J = 8.0 Hz, 1H), 7.50 (d, J = 8.9 Hz, 1H), 7.55
(d, J = 15.9 Hz, 1H), 7.65 (dd, J = 8.0, 6.8 Hz, 1H), 8.18
(d, J = 8.0 Hz, 1H) ppm. 13C NMR (75 MHz, CDCl3) d
40.3, 109.0, 112.1, 114.9, 117.8, 123.1, 124.3, 124.8,
125.7, 129.5, 133.5, 137.7, 151.6, 156.2, 163.2, 178.5 ppm.
(E)-2-(2-(Benzo[d][1,3]dioxol-5-yl)vinyl)-4H-
chromen-4-one (13)
Compound 13 was synthesized from the procedure
described for compound 6
Yield 56.4 %. Mp 211.4 °C (lit. (Momoi et al., 2005)
209–210 °C). 1H NMR (300 MHz, CDCl3) d 6.08 s, 2H), 6.37
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Med Chem Res (2013) 22:2385–2394
2391
HRMS (M)? calcd. for C19H17NO2 291.1259; found
291.1260.
J = 7.9,7.0 Hz, 1H), 7.52 (d, J = 8.2 Hz, 1H), 7.61 (d,
J = 16.0 Hz, 1H), 7.67 (s, 4H), 7.68 (dd, J = 8.2, 7.0 Hz,
1H), 8.18 (d, J = 7.9 Hz, 1H) ppm. 13C NMR (75 MHz,
CDCl3) d 111.7, 118.1, 122.9, 124.3, 125.3, 125.9, 126.1,
127.9, 134.1, 135.2, 138.5, 156.2, 161.1, 178.5 ppm.
HRMS (M?1)? calcd. for C18H11F3O2 317.0745; found
317.0784.
(E)-2-(4-Bromostyryl)-4H-chromen-4-one (17)
Compound 17 was synthesized from the procedure
described for compound 6
Yield 65.1 %. Mp 225.5 °C. 1H NMR(300 MHz,CDCl3) d 6.31
(s, 1H), 6.75 (d, J = 16.0 Hz, 1H), 7.35–7.44 (m, 3H), 7.46 (d,
J = 16.0 Hz, 1H), 7.49–7.54(m, 3H), 7.67 (dd, J = 7.0, 8.0 Hz,
1H), 8.17(d, J = 8.0 Hz, 1H) ppm. 13C NMR (75 MHz,
CDCl3) d 111.1, 118.0, 121.1, 124.1, 124.2, 125.2, 125.8, 129.2,
132.3, 133.9, 134.0, 135.6, 156.1, 161.4, 178.5 ppm. HRMS
(M)? calcd. for C17H11BrO2 325.9942; found 325.9941.
(E)-2-(4-(Trifluoromethoxy)styryl)-4H-chromen-4-one
(21)
Compound 21 was synthesized from the procedure
described for compound 6
Yield 56.1 %. Mp 170.2 °C. 1H NMR (300 MHz, CDCl3) d
6.34 (s, 1H), 6.75 (d, J = 16.1 Hz, 1H), 7.25 (d, J = 7.4 Hz,
2H), 7.37 (m, 1H), 7.52 (d, J = 7.4 Hz, 2H), 7.55 (d,
J = 16.1 Hz, 1H), 7.61 (m, 2H), 8.18 (d, J = 7.9 Hz,
1H) ppm. 13C NMR (75 MHz, CDCl3) d 110.9, 115.2, 117.7,
118.6, 119.3, 122.0, 124.1, 125.0, 128.9, 133.6, 133.7, 135.0,
149.9, 155.9, 161.1, 178.3 ppm. HRMS (M)? calcd. for
C18H11F3O3 332.0660; found 332.0667.
(E)-2-(3,4-Difluorostyryl)-4H-chromen-4-one (18)
Compound 18 was synthesized from the procedure
described for compound 6
Yield 30 %. Mp 191.3 °C. 1H NMR (300 MHz,CDCl3) d 6.31
(s, 1H), 6.85 (d, J = 16.0 Hz, 1H), 7.18 (m, 1H), 7.30 (br, 1H),
7.37 (dd, J = 8.6, 7.9 Hz, 1H), 7.40 (m, 1H), 7.48 (d,
J = 16.0 Hz, 1H), 7.49 (d, J = 7.0 Hz, 1H), 7.67 (dd, J = 8.6,
7.0 Hz, 1H), 8.16 (d, J = 7.9 Hz, 1H) ppm. 13C NMR
(75 MHz, CDCl3) d 111.3, 116.0, 116.2, 118.0, 118.2, 121.5,
124.4, 125.3, 125.9, 132.4, 134.0, 134.6, 156.1, 161.1,
178.5 ppm. HRMS (M?1)? calcd. for C17H10F2O2 285.0682;
found 285.0734.
(E)-2-(4-Nitrostyryl)-4H-chromen-4-one (22)
Compound 22 was synthesized from the procedure
described for compound 6
Yield 61.2 %. Mp 288.7 °C. 1H NMR (300 MHz, CDCl3) d
6.5 5 s, 1H), 7.46 (d, J = 16.0 Hz, 1H), 7.48 (dd, J = 8.0,
6.7 Hz, 1H), 7.71 (d, J = 8.2 Hz, 1H), 7.81 (d,
J = 16.0 Hz, 1H), 7.83 (dd, J = 8.2, 6.7 Hz, 1H), 7.98 (d,
J = 8.9 Hz, 2H), 8.02 (d, J = 8.0 Hz, 1H), 8.29 (d,
J = 8.7 Hz, 2H) ppm. 13C NMR (75 MHz, CDCl3) d 29.9,
112.4, 118.1, 124.4, 124.5, 124.8, 125.5, 126.1, 128.4,
134.2, 134.3, 141.4, 148.3, 156.2, 160.5, 178.5 ppm. HRMS
(M?1)? calcd. for C17H11NO4 294.0722; found 294.0766.
(E)-2-(4-Chlorostyryl)-4H-chromen-4-one (19)
Compound 19 was synthesized from the procedure
described for compound 6
Yield 67.7 %. Mp 232.4 °C (lit. (Silva et al., 1998)
181–183 °C). 1H NMR (300 MHz, CDCl3) d 6.32 (s, 1H), 6.74
(d, J = 16.0 Hz, 1H), 7.36–7.41 (m, 3H), 7.48–7.52 (m, 3H),
7.54 (d, J = 16.0 Hz, 1H), 7.66 (dd, J = 8.3, 8.0 Hz, 1H), 8.18
(d, J = 8.0 Hz, 1H) ppm. 13C NMR (75 MHz, CDCl3) d
111.1, 118.0, 121.1, 124.3, 125.2, 125.9, 129.0, 129.4, 133.7,
133.9, 135.6, 135.9, 156.1, 161.5, 178.5 ppm. HRMS (M)?
calcd. for C17H11ClO2 282.0448; found 282.0441.
(E)-5-Methoxy-2-(3,4,5-trimethoxystyryl)-4H-
chromen-4-one(23)
Compound 23 was synthesized from the procedure
described for compound 6
1
Yield 34.7 %. Mp 201.3 °C. H NMR (300 MHz, CDCl3)
(E)-2-(4-(Trifluoromethyl)styryl)-4H-chromen-4-one
(20)
d 3.90d, J = 10.72 Hz, 9H), 3.99 (s, 3H), 6.22 (s, 1H), 6.60
(d, J = 15.9 Hz, 1H), 6.77 (s, 2H), 6.78 (d, J = 8.5 Hz,
1H), 7.07 (d, J = 8.2 Hz, 1H), 7.44 (d, J = 15.9 Hz, 1H),
7.54 (dd, J = 8.5, 8.2 Hz, 1H) ppm. 13C NMR (75 MHz,
CDCl3) d 56.4, 56.6, 61.1, 104.9, 106.5, 110.1, 112.2,
114.9, 119.4, 130.8, 133.8, 136.4, 139.9, 153.7, 158.2,
159.7, 160.0, 178.4 ppm. HRMS (M?1)? calcd. for
C21H20O6 369.1293; found 369.1298.
Compound 20 was synthesized from the procedure
described for compound 6
1
Yield 53.5 %. Mp 175 °C. H NMR(300 MHz,CDCl3) d
6.36 (s, 1H), 6.85 (d, J = 16.0 Hz, 1H), 7.39 (dd,
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Med Chem Res (2013) 22:2385–2394
(E)-6-Methoxy-2-(3,4,5-trimethoxystyryl)-4H-
chromen-4-one(24)
1H), 6.78 (s, 2H), 7.00 (d, J = 9.0 Hz, 1H), 7.51 (d,
J = 15.9 Hz, 1H), 7.91 (d, J = 9.0 Hz, 1H) ppm. 13C
NMR (75 MHz, CDCl3) d 56.4, 56.6, 61.1, 61.8, 105.1,
109.8, 110.0, 119.1, 119.9, 121.2, 130.8, 136.9, 140.1,
145.0, 153.7, 156.8, 161.6, 178.1 ppm. HRMS (M?1)?
calcd. for C22H22O7 399.1399; found 399.1409.
Compound 24 was synthesized from the procedure
described for compound 6
Yield 36.1 %. Mp 194–195 °C. 1H NMR (300 MHz, CDCl3)
d 3.92 m, 12H), 6.31 (s, 1H), 6.68 (d, J = 15.9 Hz, 1H), 6.80
(s, 2H), 7.28 (d, J = 3.1 Hz, 1H), 7.46 (d, J = 9.1 Hz, 1H),
7.51 (d, J = 15.9 Hz, 1H), 7.56 (d, J = 3.1 Hz, 1H) ppm.
13C NMR (75 MHz, CDCl3) d 56.0, 56.4, 61.1, 105.0, 105.1,
109.8, 119.3, 119.7, 123.7, 124.8, 130.7, 136.8, 140.0, 150.9,
153.7, 157.0, 161.6, 178.3 ppm. HRMS (M?1)? calcd. for
C21H20O6 369.1293; found 369.1308.
(E)-2-(3,4,5-Trihydroxystyryl)-4H-chromen-4-one(28)
A solution of 12 (0.338 g, 1.0 mmol) in CH2Cl2 (10 ml) was
cooled to -40 °C under argon atmosphere, and boron tribromide
(1.98 g, 8.0 mmol) was added. The mixture was allowed to
warm up to room temperature over a period of 16 h and was then
cooled to -40 °C. Methanol (10 ml) was added to the reaction
mixture, the solution was evaporated in vacuo, and purified with
silica gel chromatography (ethyl acetate/hexane = 1:4) to afford
(E)-7-Methoxy-2-(3,4,5-trimethoxystyryl)-4H-
chromen-4-one(25)
1
28 (0.159 g, 54 %). Mp 170–180 °C. H NMR (300 MHz,
CDCl3) d 6.42 (s, 1H), 6.65 (s, 2H), 6.77 (d, J = 16.0 Hz, 1H),
7.44 (dd, J = 6.0, 7.5 Hz, 1H), 7.45 (d, J = 16.0 Hz, 1H), 7.70
(d, J = 8.2 Hz, 1H), 7.78 (dd, J = 8.2, 6.0 Hz, 1H), 7.99 (d,
J = 7.5 Hz, 1H) ppm. 13C NMR (75 MHz, CDCl3) d 107.5,
109.1, 116.9, 118.3, 123.7, 124.9, 125.3, 125.7, 134.2, 136.2,
137.8, 146.4, 155.6, 162.5, 177.1 ppm. HRMS (M)? calcd. for
C17H12O5 296.0685; found 296.0684.
Compound 25 was synthesized from the procedure
described for compound 6
1
Yield 75 %. Mp 203.9 °C. H NMR (300 MHz, CDCl3) d
3.91(m, 12H), 6.24 (s, 1H), 6.64 (d, J = 15.9 Hz, 1H), 6.78
(s, 2H), 6.93 (d, J = 8.7 Hz, 1H), 6.95 (d, J = 2.3 Hz, 1H),
7.46 (d, J = 15.9 Hz, 1H), 8.07 (d, J = 8.7 Hz, 1H) ppm.
13C NMR (75 MHz, CDCl3) d 29.87, 55.9, 56.4, 61.1,
100.5, 105.0, 110.6, 114.1, 118.2, 119.7, 127.2, 130.8,
136.4, 140.0, 153.7, 157.8, 161.4, 164.3, 177.9 ppm. HRMS
(M?1)? calcd. for C21H20O6 369.1293; found 369.1306.
(E)-6-Hydroxy-2-(3,4,5-trihydroxystyryl)-4H-chromen-
4-one (29)
Compound 29 was synthesized from the procedure
described for compound 28
(E)-5,7-Dimethoxy-2-(3,4,5-trimethoxystyryl)-4H-
chromen-4-one(26)
1
Yield 47.2 %. Mp 173.2 °C. H NMR (300 MHz, CDCl3)
d 6.33 (s, 1H), 6.62 (s, 2H), 6.73 (d, J = 16.0 Hz, 1H),
7.19 (d, J = 9.0 Hz, 1H), 7.26 (d, J = 2.9 Hz, 1H), 7.39
(d, J = 16.0 Hz, 1H), 7.56 (d, J = 9.0 Hz, 1H) ppm. 13C
NMR (75 MHz, CDCl3) d 15.1, 102.5, 104.7, 105.6, 107.5,
108.8, 114.9, 115.1, 117.1, 125.9, 126.8, 136.1, 143.9,
146.4, 157.4, 162.9, 179.5 ppm. HRMS (M)? calcd. for
C17H12O7 328.0583; found 328.0586.
Compound 26 was synthesized from the procedure
described for compound 6
1
Yield 66.3 %. Mp 204.2 °C. H NMR (300 MHz, CDCl3)
d 3.91 (m, 15H), 6.17 (s, 1H), 6.35 (d, J = 2.3 Hz, 1H),
6.53 (d, J = 2.3 Hz, 1H), 6.59 (d, J = 15.9 Hz, 1H), 6.77
(s, 1H), 7.41 (d, J = 15.9 Hz, 1H) ppm. 13C NMR
(75 MHz, CDCl3) d 55.8, 56.3, 56.4, 61.1, 92.9, 96.0,
104.8, 109.5, 112.1, 119.3, 130.9, 135.8, 139.7, 153.6,
159.2, 159.7, 161.0, 164.2, 177.7 ppm. HRMS (M?1)?
calcd. for C22H22O7 399.1399; found 399.1418.
(E)-7-Hydroxy-2-(3,4,5-trihydroxystyryl)-4H-chromen-
4-one (30)
Compound 30 was synthesized from the procedure
described for compound 28
(E)-7,8-Dimethoxy-2-(3,4,5-trimethoxystyryl)-4H-
chromen-4-one (27)
Yield 34.7 %. Mp 130–140 °C. 1H NMR (300 MHz, CDCl3)
d 6.27(s, 1H), 6.63(s, 2H), 6.70(d, J = 16.0 Hz, 1H), 6.87(d,
J = 8.6 Hz, 1H), 6.93 (d, J = 1.9 Hz, 1H), 7.37 (d,
J = 16.0 Hz, 1H), 7.81 (d, J = 8.6 Hz, 1H) ppm.13C NMR
(75 MHz, CDCl3) d 100.8, 104.5, 105.5, 107.9, 116.1, 117.0,
119.9, 123.8, 124.8, 133.1, 134.7, 143.9, 146.3, 157.3, 162.8,
Compound 27 was synthesized from the procedure
described for compound 6
1
Yield 48.8 %. Mp 185.8 °C. H NMR (300 MHz, CDCl3)
d 3.88–4.04 m, 15H), 6.25 (s, 1H), 6.68 (d, J = 15.9 Hz,
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Med Chem Res (2013) 22:2385–2394
2393
176.2 ppm. HRMS (M)? calcd. for C17H12O6 312.0634;
found 312.0633.
maintained in the standard medium and grown as a monolayer
in Dulbecco’s modified eagle medium (DMEM) containing
10 % fetal bovine serum, 2 mM glutamine, 100 units/ml
penicillin, and 100 g/ml streptomycin. Cultures were main-
tained at 37 °C with 5 % CO2 in a humidified atmosphere.
(E)-5,7-Hydroxy-2-(3,4,5-trihydroxystyryl)-4H-
chromen-4-one(31)
Compound 31 was synthesized from the procedure
described for compound 28
MTT assay for cell viability
Yield 29.1 %. Mp 140–150 °C. 1H NMR (300 MHz, CDCl3)
d 6.34d, J = 16.0 Hz, 1H), 6.45 (s, J = 1.92 Hz, 1H), 6.64
(d, 2H), 6.66 (d, J = 16.0 Hz, 1H), 6.72 (m, 1H), 7.42 (m,
1H) ppm. 13C NMR (75 MHz, CDCl3) d 56.04, 92.59, 97.83,
104.89, 107.10, 107.39, 116.13, 125.37, 136.32, 138.38,
146.23, 157.16, 161.24, 163.34, 165.17, 181.82 ppm. HRMS
(M)? calcd. for C17H12O7 328.0583; found 328.0587.
Cell proliferation and viability were measured by MTT
assay. Compound stock solution (10 mM in DMSO) was
prepared and stored at -20 °C, and was diluted with DMSO
to 0.1–1 mM range at room temperature before experiment.
The final percentage of DMSO in the reaction mixture was
\1 % (v/v). Cancer cells (1 9 104 cells/well) were plated
in the 96-well plates and incubated in medium for 24 h,
followed by the addition of serial dilutions of individual
compounds. Treated cells were further incubated for 48 h.
Cell survival is expressed as percentage of control cell
growth. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltet-
razolium bromide (MTT, 2 mg/ml) dye reduction assay in
96-well microplates was used. The assay is dependent on
the reduction of MTT by mitochondrial dehydrogenases of
viable cell to a blue formazan product, which come be
measured spectrophotometrically. Tumor cells were incu-
bated in each well with serial dilutions of the tested com-
pounds. After 2 days of incubation (37 °C, 5 % CO2 in a
humid atmosphere) 100 ll of MTT (2 mg/ml in PBS) was
added to each well and the plate was incubated for a further
2 h (37 °C). The resulting formazan was dissolved in 100 ll
DMSO and read at 570 nm. The percentage of growth
inhibition was calculated by the following equation: per-
centage growth inhibition = (1 9 At/Ac) 9 100, where At
and Ac represent the absorbance in treated and control
cultures, respectively. The drug concentration causing a
50 % cell growth inhibition (GI50) was determined by
interpolation from dose–response curves. All determina-
tions were carried out in four to six separated experiments.
(E)-7,8-Dihydroxy-2-(3,4,5-trihydroxystyryl)-4H-
chromen-4-one (32)
Compound 32 was synthesized from the procedure
described for compound 28
Yield 42.6 %. Mp 149–157 °C. 1H NMR (300 MHz,
CDCl3) d 6.24 (s, 1H), 6.61 (s, 2H), 6.71 (d, J = 15.9 Hz,
1H), 6.88 (d, J = 8.6 Hz, 1H), 7.32 (d, J = 8.6 Hz, 1H),
7.60 (d, J = 15.9 Hz, 1H) ppm. 13C NMR (75 MHz,
CDCl3) d 107.1, 108.3, 113.7, 115.1, 117.1, 125.8, 132.8,
135.7, 137.4, 146.2, 150.4, 161.6, 176.8 ppm. HRMS (M)?
calcd. for C17H12O7 328.0583; found 328.0583.
2-(3,4,5-Trimethoxyphenethyl)-4H-chromen-4-one (33)
To a solution of 12 (0.338, 1.0 mmol) in MeOH (10 ml), Pd/C
(5 mg, 10 % on charcoal) was added to the mixture. The reaction
mixture was degassed and filled with H2 balloon. The mixture
was stirred at room temperature for 16 h. The solid was filtered
and the filtrate was evaporated in vacuo, followed by silica gel
chromatography purification to give 33 (0.208 g, 56.4 %). Mp
133.4 °C. 1H NMR (300 MHz, CDCl3) d 2.93 (t, J = 7.4 Hz,
2H), 2.99 (t, J = 7.4 Hz, 2H), 3.81 (d, J = 10.8 Hz, 9H), 6.18
(s,1H),6.40(s,2H),7.37(d,J = 7.0 Hz, 1H), 7.42 (dd, J = 8.0,
9.0 Hz, 1H), 7.65 (dd, J = 9.0, 7.0 Hz, 1H), 8.17 (d,
J = 8.0 Hz, 1H) ppm. 13C NMR (75 MHz, CDCl3) d 29.9,
33.7, 36.4, 56.3, 61.1, 105.5, 110.5, 117.9, 123.9, 125.2, 125.9,
133.7, 135.6, 136.9, 153.5, 156.6, 168.5, 178.4 ppm. HRMS
(M)? calcd. for C20H20O5 341.1389; found 341.1387.
Statistical analysis
Data are presented as the Mean SEM (standard error of the
mean) from four to six separated experiments. Statistical
analyses were performed by Bonferroni t test method after
ANOVA for multigroup comparison and Student’s t test
method for two-group comparison. P = 0.05 was considered
significant. Analysis of linear regression (at least five data
within 20–80 % inhibition) was used to calculate GI50 value.
Cell culture
Acknowledgments Financial support from the National Science
Council of the Republic of China and Tamkang University to
A. Y. Shaw is gratefully acknowledged.
Cancer cells were purchased from Bioresource Collection and
Research Center in Hsinchu, Taiwan. Each cell line was
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Med Chem Res (2013) 22:2385–2394
strong scavengers of reactive oxygen and nitrogen species.
Bioorg Med Chem 15:6027–6036
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