Synthesis and anticancer activity of chromone-based analogs of lavendustin A

Article abstract of DOI:10.1016/j.ejmech.2010.06.030

Lavendustin A and hormothamnione were reported to exhibit cytotoxic effects on tumor cell lines. In the present studies, a series of chromone-based lavendustin analogs were synthesized as a simplified hybrid of hormothamnione and lavendustin A by the reductive-amination of formyl-chromone 5 with various amines followed by aminoalkylation. Most compounds synthesized showed significantly improved potencies compared to the standard compound 3 against most of cancer cell lines tested indicating that the removal of styryl group enhanced cancer cell growth inhibitory activities. Compound 4h and 4k showed the most potent inhibitory activities with GI₅₀ values in the range of 6.01-9.92 μg/ml on A-549 and HCT-15 cells. Chromone-based lavendustin A analogs were synthesized as a simplified hybrid of hormothamnione and lavendustin

Full text of DOI:10.1016/j.ejmech.2010.06.030

European Journal of Medicinal Chemistry 45 (2010) 4288e4292
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and anticancer activity of chromone-based analogs of lavendustin A
,
Dong Hyuk Nam a, Ki Yong Lee a, Chang Sang Moon b, Yong Sup Lee a
*
a Department of Life and Nanopharmaceutical Science & Department of Pharmaceutical Science, College of Pharmacy, Kyung Hee University,
1 Hoegi-Dong, Seoul 130-701, Republic of Korea
b Division of Life Sciences, Korea Institute of Science & Technology, P.O. Box 131 Cheongryang, Seoul 130-650, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Lavendustin A and hormothamnione were reported to exhibit cytotoxic effects on tumor cell lines. In the
present studies, a series of chromone-based lavendustin analogs were synthesized as a simplified hybrid
of hormothamnione and lavendustin A by the reductive-amination of formyl-chromone 5 with various
amines followed by aminoalkylation. Most compounds synthesized showed significantly improved
potencies compared to the standard compound 3 against most of cancer cell lines tested indicating that
the removal of styryl group enhanced cancer cell growth inhibitory activities. Compound 4h and 4k
Received 6 May 2010
Received in revised form
21 May 2010
Accepted 20 June 2010
Available online 25 June 2010
showed the most potent inhibitory activities with GI50 values in the range of 6.01e9.92 mg/ml on A-549
and HCT-15 cells.
Keywords:
Chromone
Lavendustin A
Growth inhibition
A-431
Ó 2010 Elsevier Masson SAS. All rights reserved.
KB
1. Introduction
as HCT-15 indicating that the styryl group in this series of the
compounds affects the tumor cell type specificity. Accordingly, to
test if the styryl moiety is responsible for the altered tumor spec-
ificity, we designed a series of the simplified chromone-based
lavendustin analogs, which have no styryl group in the structure,
and evaluated their growth inhibitory activities on various human
cancer cell lines (Fig. 1).
Some 2-styrylchromones including hormothamnione (1) have
been identified from the blue-green algae species and reported to
exhibit cytotoxic effect on KB tumor cell line [1,2]. Due to the
unique structure and cytotoxic effects, syntheses of 1 and its
derivatives have been reported [3,4]. Lavendustin A (2), a metabo-
lite of Streptomyces griseolavendus, has also been known to have
cytotoxic effect especially on A-431 cell line [5]. Stilbene and ben-
zylanilines derivatives of this compound were synthesized to
reduce polarity or simplify the structure of 2 [6e8]. Bis-hydrox-
yquinoline-substituted benzylamine derivatives, which have
similar structure to 2, were also identified from house chemical
library as potent antitumor agents on KB cell lines [9]. We recently
reported the synthesis and cytotoxic activities of a series of styr-
ylchromones as analogs of hormothamnione [10] or hybrids of
2. Chemistry
Chromone-based lavendustin analog 4 were synthesized by the
slight modification of the previous procedures [11] used in the
synthesis of styrylchromone derivatives (Scheme 1). To investigate
the effects of nitrogen substituents on cytotoxicities, we designed
a series of compounds 4, where a chromone ring is fixed, while
substituents on nitrogen were varied. Two amine substituents on
chromone ring were introduced by reductive-amination followed
by aminoalkylation reaction.
The formyl group in compound 5 was reacted with benzyl or
phenethyl amine derivatives in methanol followed by treatment of
NaBH4 to provide 6 [12]. The second amine substituents were
introduced by the aminoalkylation of 8 with various alkyl or benzyl
halides using DBU as a base in DMSO to obtain compound 7. Finally,
PMB protecting group in compounds 7 was removed by treatment
of trifluoroacetic acid (TFA) in CH2Cl2 to provide chromone deriv-
atives 4.
hormothamnione and lavendustin
A [11]. Although hormo-
thamnione (1) was known to have potent cytotoxic effects on KB
cell lines, the synthesized styrylchromones (e.g. 3) exhibited
moderate to no cytotoxicities on KB cell line under the concentra-
tion of 100
mg/ml. Interestingly, some of those synthesized
compounds exhibited potent cytotoxicities on other cell line such
* Corresponding author. Tel.: þ82 2 961 0370; fax: þ82 2 966 3885.
E-mail address: kyslee@khu.ac.kr (Y.S. Lee).
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.06.030

D.H. Nam et al. / European Journal of Medicinal Chemistry 45 (2010) 4288e4292
4289
group (4f, 4g, 4j, 4k) decreased inhibitory activities on these
cell lines.
2-Styrylchromones including hormothamnione (1) have been
reported to exhibit cytotoxic effect on KB tumor cell line [1,2].
However, the hybridization of 1 with lavendustin A (2) leading to 3,
which bearing styryl group, decreased cytotoxic effect in 1 against
KB cell line [11]. Interestingly, in this work, the removal of styryl
group in 3, thus decreased the structural character of 1, increased
cytotoxic effects on KB cell line while retaining cytotoxic effect on
HCT-15. Furthermore, compounds 4a, 4c and 4h exhibited
moderate cytotoxic effects on A-431 as was observed in lavendustin
A and its mimics [5e8]. These results revealed that the simplifi-
cation of 3 by the removal of styryl group to lead 4 improved
cytotoxic effects on all cell lines tested including KB cell line. Our
study on the extended synthesis of derivatives of 4 for detailed
structureeactivity relationship as well as mechanism study is in
progress.
4. Conclusion
In this report, we synthesized chromone-based lavendustin
analogs 4 by the reductive-amination of formyl-chromone 5 with
various amines followed by aminoalkylation and tested their
cytotoxic effects on six human cancer cell lines. Most compounds
synthesized in this study showed significantly improved potencies
compared to the standard compound 3 against most of cancer cell
lines tested. This observation supports that the structural simpli-
fication of 3 by the removal of styryl group can enhance the
inhibitory activities against cancer cell growth. Compound 4h and
4k showed the most potent inhibitory activities with GI50 values in
Fig. 1. Structures of homothamnione (1), lavendustin A (2) and their hybrids 3e4.
3. Biological studies and discussion
The synthesized compounds 4 were evaluated for their ability to
inhibit the growth of cancer cell lines. Six human cancer cell lines
were used: epidermoid carcinoma (A-431), lung carcinoma (A-
549), colon (HCT-15), oral epidermoid carcinoma (KB), malignant
melanoma (SK-MEL-2) and ovary malignant (SK-OV3). The results
are shown as GI50 values in Table 1, which are mean values from
three independent experiments. To compare these data with that of
standard, we inserted the growth inhibitory activity of styr-
ylchromone 3 into the data set.
the range of 6.01e9.92 mg/ml on A-549 and HCT-15 cells.
5. Experimental section
Most compounds synthesized showed improved cytotoxicities
against all cancer cell lines tested with varied potencies when
compared to those of the standard compound 3. Compounds 4a
and 4c exhibited broad spectrum of cell growth inhibitory activi-
ties, while compound 4h and 4k showed the most potent growth
5.1. Instrumentation and chemicals
1H and 13C NMR spectra were recorded on a Gemini Varian-300
(300 and 75 MHz, respectively). Analytical thin layer chromatog-
raphies (TLC) were carried out by precoated silica gel (E. Merck
Kiesegel 60F254 layer thickness 0.25 mm). Flash column chroma-
tographies were performed with Merck Kiesegel 60 Art 9385
(230e400 mesh). All solvents used were purified according to
standard procedures.
inhibition activities with GI50 values in the range of 6.01e9.92 mg/
ml on specific cell lines, A-549 and HCT-15. It is evident that the
growth inhibitory activities of 4 were increased against A-549 and
KB cells. They also showed moderate activities against A-431 and
SK-MEL-2 cells, however, the introduction of ethyl or 4-nitrobenzyl
Scheme 1. Synthesis of chromone-based lavendustin A analogs 4.

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D.H. Nam et al. / European Journal of Medicinal Chemistry 45 (2010) 4288e4292
Table 1
The growth inhibition activity of 4ae4k on cancer cell lines in vitro.
Entry
R1
R2
Growth inhibition activity of 4 (IC50 mg/mL)
A-431
A-549
HCT-15
KB
SK-MEL-2
SK-OV3
4a
4b
4c
4d
4e
4f
4g
4h
4i
Benzyl
Benzyl
Benzyl
Benzyl
Benzyl
4-Methoxybenzyl
Phenethyl
4-Methoxyphenethyl
3,4-Dimethoxyphenethyl
Ethyl
4-Nitrobenzyl
2-Naphthylmethyl
4-Methoxybenzyl
Ethyl
19.51 ꢁ 0.7
44.67 ꢁ 5.8
18.51 ꢁ 1.6
25.21 ꢁ 2.3
>100
11.91 ꢁ 3.7
14.13 ꢁ 4.1
12.33 ꢁ 1.8
16.62 ꢁ 2.4
26.11 ꢁ 5.6
38.72 ꢁ 9.5
24.47 ꢁ 8.6
6.01 ꢁ 2.7
11.32 ꢁ 1.0
10.72 ꢁ 1.2
11.71 ꢁ 1.7
15.80 ꢁ 6.4
31.50 ꢁ 11.5
22.45 ꢁ 4.3
28.60 ꢁ 7.8
6.89 ꢁ 2.6
15.10 ꢁ 1.5
42.66 ꢁ 8.7
14.50 ꢁ 1.3
16.05 ꢁ 2.2
24.35 ꢁ 3.5
47.41 ꢁ 14.2
24.40 ꢁ 9.1
17.62 ꢁ 4.9
17.78 ꢁ 32
32.60 ꢁ 6.9
10.84 ꢁ 3.3
34.98 ꢁ 6.6
17.78 ꢁ 2.6
78.60 ꢁ 4.1
17.38 ꢁ 2.7
19.95 ꢁ 4.5
21.88 ꢁ 3.5
60.26 ꢁ 10.8
>100
18.98 ꢁ 1.7
24.55 ꢁ 5.6
21.58 ꢁ 1.3
65.04 ꢁ 8.7
41.69 ꢁ 3.8
57.54 ꢁ 5.2
>100
>100
>100
>100
>100
Benzyl
4-Methoxybenzyl
4-Methoxybenzyl
4-Methoxybenzyl
4-Methoxybenzyl
Phenethyl
41.95 ꢁ 5.6
>100
16.40 ꢁ 3.1
38.9 ꢁ 8.2
>100
>100
62.46 ꢁ 9.7
32.67 ꢁ 6.3
9.92 ꢁ 3.6
53.70 ꢁ 4.8
43.21 ꢁ 9.8
7.68 ꢁ 2.2
31.65 ꢁ 3.5
57.54 ꢁ 6.9
74.13 ꢁ 8.3
>100
4j
4k
3
Phenethyl
4-Nitrobenzyl
61.01 ꢁ 12.1
e
17.91 ꢁ 2.9
49.37 ꢁ 1.1
e
5.2. Synthesis
5.2.1. General procedure for the synthesis of (6aee)
To a stirred solution of 5 (1.0 eq.) and amine (2.0 eq.) in MeOH
was added portionwise NaBH4 (2.0 eq.) at 0 ꢀC. After 30 min, the
mixture was warmed up to room temperature and further stirred
for 1 h. The reaction mixture was poured into water and extracted
with EtOAc. The organic layer was dried over MgSO4, concentrated,
and purified by flash column chromatography (CH2Cl2/
CH3OH ¼ 98:2) to afford 6.
procedure from the compound 5 and 3,4-dimethoxyphenethyl-
amine. Yield: 75%; 1H NMR (300 MHz, CDCl3)
8.07 (1H, d,
J ¼ 8.8 Hz), 7.23 (2H, d, J ¼ 8.6 Hz), 7.02 (2H, d, J ¼ 8.9 Hz), 6.90 (1H,
d, J ¼ 8.8 Hz), 6.70 (2H, d, J ¼ 8.9 Hz), 6.60 (2H, d, J ¼ 8.6 Hz), 6.07
(1H, s), 5.05 (2H, s), 4.06 (3H, s), 3.81 (3H, s), 3.77 (2H, s), 2.82e2.71
(4H, br s), 2.28 (3H, s).
d
5.2.2. General procedure for the synthesis of 7aek and 4aek
To a solution of 6 (1.0 eq.) in DMSO was added (R2-Br or R2-I,
1.2 eq.) and DBU (1.0 eq.) and stirred at rt for 1.5 h. The reaction
mixture was diluted with EtOAc and washed with water. The
organic layer was dried over MgSO4, concentrated, and purified by
silica gel column chromatography (CH2Cl2/MeOH ¼ 98:2) to afford
7aek. A solution of 7 (1.0 eq.) in 20% trifluoroacetic acid in CH2Cl2
(5.0 mL) was stirred at rt for 1 h. The mixture was washed by 10%
HaHCO3 aqueous solution and the organic layer was dried over
MgSO4, concentrated, and purified by silica gel column chroma-
tography (CH2Cl2/CH3OH ¼ 98:2) to afford 4aek.
5.2.1.1. 8-((Benzylamino)methyl)-7-(4-methoxybenzyloxy)-2-
methyl-4H-chromen-4-one (6a). The compound 6a (85 mg,
0.21 mmol) was obtained according to the above general procedure
from the compound 5 and benzylamine. Yield: 66%; 1H NMR
(300 MHz, CDCl3)
d
8.11 (1H, d, J ¼ 9.0 Hz), 7.30 (2H, d, J ¼ 8.7 Hz),
7.20e7.18 (4H, m), 7.07 (1H, d, J ¼ 9.0 Hz), 6.90 (2H, d, J ¼ 8.7 Hz),
6.09 (1H, s), 5.12 (2H, s), 4.02 (2H, s), 3.83 (3H, s), 3.71 (2H, s), 2.29
(3H, s).
5.2.2.1. 8-((Dibenzylamino)methyl)-7-hydroxy-2-methyl-4H-chro-
men-4-one (4a). Compound 4a was obtained according to the
above procedure from the compound 6a and benzyl bromide. 7a:
5.2.1.2. 8-((4-Methoxybenzylamino)methyl)-7-(4-methox-
ybenzyloxy)-2-methyl-4H-chromen-4-one (6b). Compound 6b was
prepared as described previously [11].
Yield: 64%; 1H NMR (300 MHz, CDCl3)
d
8.08 (1H, d, J ¼ 8.8 Hz),
7.44e6.97 (15H, m), 6.11 (1H, s), 5.14 (2H, s), 3.93 (2H, s), 3.87 (3H,
5.2.1.3. 7-(4-Methoxybenzyloxy)-2-methyl-8-((phenethylamino)
methyl)-4H-chromen-4-one (6c). Compound 6c was prepared as
described previously [11].
s), 3.63 (4H, s), 2.28 (3H, s). 4a: Yield: 73%; 1H NMR (300 MHz,
CDCl3)
d
7.99 (1H, d, J ¼ 8.8 Hz), 7.36e7.29 (10H, m), 6.85 (1H, d,
J ¼ 8.8 Hz), 6.07 (1H, s), 4.01 (2H, s), 3.70 (4H, s), 2.34 (3H, s); 13C
NMR (75 MHz, CDCl3)
d 177.85, 164.86, 163.30, 155.55, 136.15,
5.2.1.4. 7-(4-Methoxybenzyloxy)-8-((4-methoxyphenethylamino)
methyl)-2-methyl-4H-chromen-4-one (6d). The compound 6d
(1.98 g, 4.31 mmol) was obtained according to the above general
procedure from the compound 5 and 4-methoxyphenenylamine.
129.75, 128.85, 128.11, 126.10, 116.42, 115.05, 110.23, 108.05, 58.27,
48.99, 20.47.
5.2.2.2. 8-((Benzyl(4-methoxybenzyl)amino)methyl)-7-hydroxy-2-
methyl-4H-chromen-4-one (4b). Compound 4b was obtained
according to the above procedure from the compound 6b and
Yield: 70%; 1H NMR (300 MHz, CDCl3)
d
8.12 (1H, d, J ¼ 8.8 Hz),
7.34e6.80 (12H, m), 6.92 (1H, d, J ¼ 8.8 Hz), 6.11 (1H, s),5.15 (2H, s)
4.06 (2H, s), 3.84e3.80 (6H, m), 3.62 (2H, s), 2.33 (3H, s).
benzyl bromide. 7b: Yield: 85%, 1H NMR (300 MHz, CDCl3)
d 8.02
(1H, d, J ¼ 8.8 Hz), 7.35 (2H, d, J ¼ 8.7 Hz), 7.29e7.17 (6H, m),
6.98e6.91 (4H, m), 6.74 (2H, d, J ¼ 8.7 Hz), 6.05 (1H, s), 5.08 (2H, s),
3.85 (2H, s), 3.81 (3H, s), 3.74 (3H, s), 3.58 (2H, s), 2.58 (3H, s). 4b:
5.2.1.5. 8-((3,4-Dimethoxyphenethylamino)methyl)-7-(4-methox-
ybenzyloxy)-2-methyl-4H-chromen-4-one (6e). The compound 6e
(2.26 g, 4.62 mmol) was obtained according to the above general
Yield: 72.7%; 1H NMR (300 MHz, CDCl3)
d
8.01 (1H, d, J ¼ 8.8 Hz),

D.H. Nam et al. / European Journal of Medicinal Chemistry 45 (2010) 4288e4292
4291
7.40e7.24 (7H, m), 6.94e6.87 (3H, m), 6.11 (1H, s), 4.04 (2H, s), 3.83
obtained according to the above procedure from the compound 6b
and 4-nitrobenzyl bromide. 7g: Yield: 53%; 1H NMR (300 MHz,
(3H, s), 3.73 (2H, s), 3.69 (2H, s), 2.38 (3H, s); 13C NMR (75 MHz,
CDCl3)
d
177.94, 164.78, 163.36, 159.51, 155.58, 136.08, 131.06,
CDCl3)
d
8.05 (1H, d, J ¼ 8.7 Hz), 7.97 (2H, d, J ¼ 9.0 Hz), 7.40e7.33
129.77, 128.87, 128.13, 127.85, 126.20, 115.14, 114.25, 110.30, 107.96,
58.16, 57.58, 55.38, 48.76, 20.49.
(4H, m), 7.17 (2H, d, J ¼ 9.0 Hz), 7.02 (1H, d, J ¼ 8.7 Hz), 6.94 (2H, d,
J ¼ 8.4 Hz), 6.77 (2H, d, J ¼ 8.4 Hz), 6.09 (1H, s), 5.10 (2H, s), 3.91 (2H,
s), 3.86 (3H, s), 3.75 (3H, s), 3.61 (2H, s), 3.53 (2H, s), 2.29 (3H, s). 4g:
5.2.2.3. 8-((Benzyl(phenethyl)amino)methyl)-7-hydroxy-2-methyl-
4H-chromen-4-one (4c). Compound 4c was obtained according to
the above procedure from the compound 6c and benzyl bromide.
Yield: 86%; 1H NMR (300 MHz, CDCl3)
d
8.24 (2H, d, J ¼ 8.4 Hz), 8.01
(1H, d, J ¼ 8.8 Hz), 7.52 (2H, d, J ¼ 8.4 Hz), 7.29e7.22 (2H, m),
6.94e6.86 (3H, m), 6.11 (1H, s), 4.05 (2H, s), 3.82 (3H, s), 3.81 (2H, s),
7c: Yield: 76%; 1H NMR (300 MHz, CDCl3)
d
8.06 (1H, d, J ¼ 9.0 Hz),
3.68 (2H, s), 2.39 (3H, s); 13C NMR (75 MHz, CDCl3)
d 177.63, 164.69,
7.31e7.10 (7H, m), 6.99 (1H, d, J ¼ 9.0 Hz), 6.94e6.05 (3H, m), 6.05
162.72, 159.53, 155.38, 147.62, 143.88, 130.84, 130.26, 127.17, 126.36,
123.93, 116.47, 114.95, 114.24, 110.22, 107.45, 57.78, 57.44, 55.24,
49.01, 20.36.
(1H, s), 5.08 (2H, s), 3.91 (2H, s), 3.77(3H, s), 3.69(2H, s), 2.20 (3H, s).
4c: Yield: 81%; 1H NMR (300 MHz, CDCl3)
d
8.02 (2H, d, J ¼ 8.8 Hz),
7.38e7.09 (10H, m), 6.87 (1H, d, J ¼ 1.6 Hz), 6.10 (1H, s), 4.14 (2H, s),
3.81 (2H, s), 2.97 (4H, br s), 2.37 (3H, s); 13C NMR (75 MHz, CDCl3)
5.2.2.8. 7-Hydroxy-8-(((4-methoxybenzyl)(naphthalen-2-ylmethyl)
amino)methyl)-2-methyl-4H-chromen-4-one (4h). Compound 4h
was obtained according to the above procedure from the
compound 6b and naphthyl bromide. Yield: 62%; 1H NMR
d
177.73, 164.60, 163.38, 155.38, 138.57, 135.61, 129.55, 128.67,
128.54, 128.50, 127.99, 126.46, 126.06, 116.18, 115.05, 110.12, 107.57,
58.29, 54.91, 49.72, 32.725, 20.31.
(300 MHz, CDCl3)
d
8.00 (1H, d, J ¼ 8.8 Hz), 7.76e7.65 (4H, m),
5.2.2.4. 8-((Benzyl(4-methoxyphenethyl)amino)methyl)-7-hydroxy-
2-methyl-4H-chromen-4-one (4d). Compound 4d was obtained
according to the above procedure from the compound 6d and
7.42e7.34 (5H, m), 7.22 (2H, d, J ¼ 8.7 Hz), 6.95e6.89 (2H, m), 6.75
(2H, d, J ¼ 8.7 Hz), 6.03 (1H, s), 5.06 (2H, s), 3.89 (2H, s), 3.80 (3H, s),
3.73 (3H, s), 3.68 (2H, s), 3.54 (2H, s), 2.16 (3H, s). 4h: Yield: 76%; 1H
benzyl bromide. 7d: Yield: 92%; 1H NMR (300 MHz, CDCl3)
d
8.11
NMR (300 MHz, CDCl3)
d
8.01 (1H, d, J ¼ 8.8 Hz), 7.91e7.75 (4H, m),
(1H, d, J ¼ 8.8 Hz), 7.37e7.23 (7H, m), 7.05 (1H, d, J ¼ 8.8 Hz),
6.94e6.86 (4H, m), 6.75e6.70 (2H, m), 6.10 (1H, s), 5.14 (1H, s), 3.96
(2H, s), 3.83 (3H, s), 3.77 (3H, s), 3.73 (2H, s), 2.72 (3H, s), 2.27 (3H,
7.54e7.45 (3H, m), 7.30e7.26 (2H, m), 6.95e6.88 (3H, m), 6.10 (1H,
s), 4.07 (2H, s), 3.89 (2H, s), 3.83 (3H, s), 3.73 (2H, s), 2.34 (3H, s); 13C
NMR (75 MHz, CDCl3)
d 177.94, 164.81, 163.33, 159.51, 155.57,
s), 2.20 (1H, s). 4d: Yield: 64%; 1H NMR (300 MHz, CDCl3)
d
8.02
133.48, 133.31, 133.07, 129.09, 128.83, 127.87, 127.82, 127.18, 126.54,
126.38, 126.22, 116.44, 115.16, 114.26, 110.30, 107.96, 58.30, 57.71,
55.39, 48.68, 29.82, 20.50.
(1H, d, J ¼ 8.4 Hz), 7.38e6.80 (6H, m), 6.11 (1H, s), 4.14 (2H, s), 3.82
(3H, s), 3.79 (2H, s), 2.90 (4H, br s), 2.36 (3H, s),1.28 (1H, s); 13C NMR
(75 MHz, CDCl3)
d 177.97, 164.83, 163.63, 158.39, 155.61, 135.61,
130.62, 129.78, 129.60, 128.87, 128.22, 126.33, 116.33, 115.32, 114.16,
110.30, 107.67, 58.51, 55.35, 55.31, 49.81, 31.99, 29.79, 20.49.
5.2.2.9. 8-((Bis(4-methoxybenzyl)amino)methyl)-7-hydroxy-2-
methyl-4H-chromen-4-one (4i). Compound 4i was obtained
according to the above procedure from the compound 6b and 1-
(chloromethyl)-4-methoxybenzene. 7i: Yield: 74%; 1H NMR
5.2.2.5. 8-((Benzyl(3,4-dimethoxyphenethyl)amino)methyl)-7-
hydroxy-2-methyl-4H-chromen-4-one (4e). Compound 4e was
obtained according to the above procedure from the compound 6e
and benzyl bromide. 7e: Yield: 87%; 1H NMR (300 MHz, CDCl3)
(300 MHz, CDCl3)
7.29e7.20 (5H, m), 7.04e6.95 (4H, m), 6.81e6.77 (5H, m), 6.10 (1H,
d
8.01 (1H, d, J ¼ 8.8 Hz), 7.39 (2H, d, J ¼ 8.4 Hz),
s), 5.32 (3H, s), 5.14 (2H, s), 3.87 (6H, s), 3.79 (6H, s), 3.51 (4H, s),
d
8.11 (1H, d, J ¼ 8.4 Hz), 7.37e7.22 (8H, m), 7.06 (1H, m), 6.91(2H,
2.30 (3H, s). 4i: Yield: 71%; 1H NMR (300 MHz, CDCl3)
d 7.99 (1H, d,
m), 6.68 (1H, d J ¼ 8.4 Hz), 6.48 (2H, m), 6.10 (1H, s), 5.14 (1H, s),
J ¼ 8.8 Hz), 7.26e7.22 (4H, m), 6.93e6,84 (6H, m), 6.10 (1H, s), 4.01
3.96 (2H, s), 3.84 (3H, s), 3.83 (3H, s), 3.76 (3H, s), 3.73 (3H, s), 2.72
(2H, s), 3.81 (6H, s), 3.66 (4H, s), 2.37 (3H, s); 13C NMR (75 MHz,
(4H, s), 2.28 (3H, s). 4e: Yield: 84%; 1H NMR (300 MHz, CDCl3)
d
8.01
CDCl3) d 177.91, 164.74, 163.42, 159.45, 155.55, 131.02, 127.96, 126.11,
(1H, d, J ¼ 8.8 Hz), 7.37e7.29 (5H, m), 6.90e6.57 (4H, m), 6.10 (1H,
116.36, 115.12, 114.21, 110.27, 108.01, 57.41, 55.37, 48.56, 20.49.
s), 4.14 (2H, s), 3.86 (2H, s), 3.80 (6H, s), 2.90 (4H, br s), 2.36 (3H, s),
1.28 (2H, s); 13C NMR (75 MHz, CDCl3)
d
177.90, 164.80, 163.54,
5.2.2.10. 8-((Ethyl(phenethyl)amino)methyl)-7-hydroxy-2-methyl-
4H-chromen-4-one (4j). Compound 4j was obtained according to
the above procedure from the compound 6c and iodoethane. 7j:
155.60, 149.13, 147.83, 135.75, 131.26, 129.75, 128.84, 128.18, 126,30,
120.64, 116.36, 115.23, 111.87, 111.45, 110.30, 107.69, 58.58, 56.02,
55.89, 55.25, 49.91, 32.58, 29.79, 20.48.
Yield: 65%; 1H NMR (300 MHz, CDCl3)
d
8.09 (1H, d, J ¼ 9.3 Hz), 7.31
(2H, d, J ¼ 8.7 Hz), 7.21e7.02 (2H, m), 6.86 (2H, d, J ¼ 8.1 Hz), 6.08
(1H, s), 5.09 (2H, s), 3.87(2H, s), 3.77 (3H, s), 2.74 (4H, br s), 2.68 (2H,
q, J ¼ 7.2 Hz), 2.31 (3H, s), 1.25 (3H, t, J ¼ 7.2 H). 4j: Yield: 68%; 1H
5.2.2.6. 8-((Ethyl(4-methoxybenzyl)amino)methyl)-7-hydroxy-2-
methyl-4H-chromen-4-one (4f). Compound 4f was obtained
according to the above procedure from the compound 6b and
NMR (300 MHz, CDCl3)
d
8.01 (1H, d, J ¼ 8.8 Hz), 7.36e7.17 (6H, m),
iodoethane. 7f: Yield: 80%; 1H NMR (300 MHz, CDCl3)
d
8.00 (1H, d,
6.86 (1H, d, J ¼ 8.8 Hz), 6.10 (1H, s), 4.14 (2H, s), 2.93 (4H, br s), 2.82
J ¼ 7.9 Hz), 7.35 (2H, d, J ¼ 8.7 Hz), 7.16 (2H, d, J ¼ 8.1 Hz), 7.00 (1H, d,
J ¼ 7.9 Hz), 6.92 (2H, d, J ¼ 2.7 Hz), 6.80 (2H, d, J ¼ 2.7 Hz), 6.72 (2H,
d, J ¼ 11.4 Hz), 6.08 (1H, s), 5.11 (2H, s), 3.85 (2H, s), 3.81 (3H, s), 3.75
(3H, s), 3.54 (2H, s), 2.50 (2H, q J ¼ 6.6 Hz), 2.30 (3H, s), 1.04 (3H, t
(2H, q, J ¼ 7.2 Hz), 2.37 (3H, s) 1.22 (3H, t, J ¼ 7.2 Hz); 13C NMR
(75 MHz, CDCl3)
d 177.82, 164.63, 163.97, 155.45, 138.70, 128.63,
128.54, 126.54, 126.02, 116.00, 115.24, 110.15, 107.29, 54.84, 49.95,
47.46, 32.85, 20.37.
J ¼ 6.6 Hz). 4f: Yield: 57%; 1H NMR (300 MHz, CDCl3)
d 8.00 (1H, d,
J ¼ 8.8 Hz), 7.27 (2H, d, J ¼ 7.6 Hz), 6.93e6.85 (3H, m), 6.10 (1H, s),
5.2.2.11. 7-Hydroxy-2-methyl-8-(((4-nitrobenzyl)(phenethyl)amino)
methyl)-4H-chromen-4-one (4k). Compound 4k was obtained
according to the above procedure from the compound 6c and 4-
nitrobenzyl bromide. 7k: Yield: 70%; 1H NMR (300 MHz, CDCl3)
4.06 (2H, s), 3.82 (3H, s), 3.71 (2H, s), 2.72 (2H, q, J ¼ 8.2 Hz), 2.37
(3H, s), 1.23 (3H, t, J ¼ 8.2 Hz); 13C NMR (75 MHz, CDCl3)
d 177.94,
164.71, 163.95, 159.46, 130.98, 127.77, 126.11, 116.19, 115.29, 114.19,
110.27, 107.68, 57.16, 55.37, 49.09, 47.13, 29.79, 20.49.
d
8.09 (1H, d, J ¼ 9.0 Hz), 7.95 (2H, d, J ¼ 8.7 Hz), 7.30 (4H, d,
J ¼ 8.7 Hz), 7.16 (3H, d, J ¼ 7.2 Hz), 7.03 (1H, d, J ¼ 9.0 Hz), 6.95e6.87
(4H, m), 6.09 (1H, s), 5.08 (2H, s), 3.96 (2H, s), 3.79 (3H, s), 3.75 (2H,
s), 2.73 (4H, s), 2.27 (3H, s). 4k: Yield: 89%, 1H NMR (300 MHz,
5.2.2.7. 7-Hydroxy-8-(((4-methoxybenzyl)(4-nitrobenzyl)amino)
methyl)-2-methyl-4H-chromen-4-one (4g). Compound 4f was

4292
D.H. Nam et al. / European Journal of Medicinal Chemistry 45 (2010) 4288e4292
CDCl3)
d
8.20 (2H, d, J ¼ 8.8 Hz), 8.03 (1H, d, J ¼ 8.8 Hz), 7.44 (2H, d,
solution and plates were left on a plate shaker for at least 10 min.
The optical density was measured using a microplate reader (Ver-
samax, Molecular Devices) with a 520 nm wavelength. The inhib-
itor concentration, which inhibits cell growth by 50%, was assigned
as GI50 value.
J ¼ 4.4 Hz), 7.30e7.25 (3H, m), 7.12e7.07 (2H, m), 6.89 (1H, d,
J ¼ 8.8 Hz), 6.16 (1H, s), 4.18 (2H, s), 3.86 (2H, s), 2.95 (4H, br s), 2.38
(3H, s); 13C NMR (75 MHz, CDCl3)
d 177.61, 164.69, 162.83, 155.43,
147.61, 143.43, 138.16, 130.16, 128.70, 128.50, 126.72, 126.49, 123.88,
116.46, 115.05, 110.27, 107.20, 57.63, 55.30, 49.98, 32.83, 20.37.
Acknowledgements
5.3. Biological test
This work was supported by the Basic Science Research Program
through the National Research Foundation of Korea (NRF) funded
by MEST (2010-0016080).
RPMI 1640 medium (Gibco BRL), fetal bovine serum (FBS),
penicillin, and streptomycin were purchased from Life Technologies
Inc.(Grand Island, NY). Sulforhodamine B, and dimethyl sulfoxide
(DMSO) were purchased from Sigma Chemical Co.(MO, U.S.A.).
Human epidermoid carcinoma (A-431), human lung cancer (A-
549), human oral epidermoid carcinoma (KB), human colon (HCT-
15), human melanoma (SK-MEL-2) and ovary malignant (SK-OV3)
cancer cell limes were supplied from the Korean Cell Line Bank,
Seoul National University. Growth inhibition activity of the
synthesized compounds against human cancer cell lines was
investigated using the SRB assay as described previously [13].
Briefly, all cell lines were grown in RPMI 1640 supplemented with
10% (v/v) heat inactivated FBS and maintained at 37 ꢀC in
a humidified atmosphere with 5% CO2. The cells (5 ꢂ 103 cells/well
for A-431, KB, SK-MEL-2, HCT-15 and 2 ꢂ 103 cells/well for A-549)
were seeded into 96-well plate. Various concentrations of samples
were added to each well in triplicate, then incubated at 37 ꢀC with
5% CO2 for 72 h such that time cells are in the exponential phase of
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