Design, synthesis and evaluation of cytotoxicity of novel chromeno[4,3-b]quinoline derivatives

Article abstract of DOI:10.1002/ardp.201000196

In the present work 15 new 1,4-dihydropyridines (DHPs) bearing a coumarin ring were synthesized and assessed on 4 different human cancer cell lines (HeLa, K562, LS180, and MCF-7). Although, all the derivatives were inactive on LS180 cell line, the results

Full text of DOI:10.1002/ardp.201000196

Arch. Pharm. Chem. Life Sci. 2011, 2, 111–118
111
Full Paper
Design, Synthesis and Evaluation of Cytotoxicity of Novel
Chromeno[4,3-b]quinoline Derivatives
Ramin Miri1, Radineh Motamedi2, Mohammad Reza Rezaei2, Omidreza Firuzi1, Azita Javidnia3, and
Abbas Shafiee3
1 Medicinal & Natural Products Chemistry Research Center, Shiraz University of Medical Sciences, Shiraz,
Iran
2 Department of Chemistry, Payam Noor University, Delijan, Iran
3 Department of Medicinal Chemistry, Faculty of Pharmacy, and Pharmaceutical Sciences Research Center,
Tehran University of Medical Sciences, Tehran, Iran
In the present work 15 new 1,4-dihydropyridines (DHPs) bearing a coumarin ring were synthesized
and assessed on 4 different human cancer cell lines (HeLa, K562, LS180, and MCF-7). Although, all the
derivatives were inactive on LS180 cell line, the results on other cells showed that these compounds
had weak to moderate antitumoral activities and their IC50 ranged from 25 to >100 mM. Among the
synthesized compounds, 7-(2-nitrophenyl)-8,9,10,12-tetrahydro-7H-chromeno[4,3-b]quinoline-6,8-
dione (6a) demonstrated the highest activity (IC50 range in different cell lines: 25.4–58.6 mM).
Furthermore, the calcium channel antagonist activity of the derivatives, an undesired effect when
these compounds are used as antitumoral agents, was much lower than nifedipine, a reference
antagonist. In conclusion, this group of compounds seems to have promising biological properties
and further investigation on this group could potentially lead to the discovery of cytotoxic agents with
low calcium channel blocking activity.
Keywords: Calcium channel antagonist activity / Cytotoxicity / 1,4-Dihydropyridines / 4-Hydroxycoumarins
Received: July 6, 2010; Revised: August 16, 2010; Accepted: August 20, 2010
DOI 10.1002/ardp.201000196
Introduction
synthetic community in the 1,4-dihydropyridine core [7]. It
is well established that slight structural modifications on the
DHP ring may result in remarkable changes in pharmaco-
logical effects [8–10]. For this reason, considerable effort has
been focused on the synthesis of new 1,4-DHPs with wider
applicability and higher efficiency. Hantzsch esters and acri-
dines are two important DHPs’ generation and NADH models
(Fig. 1).
1,4-Dihydropyridines (DHPs), particularly 4-aryl-substituted-
1,4-dihydropridines, exhibit a wide range of biological prop-
erties such as calcium channel blocking activity [1]. Recently,
DHPs were recognized as reversing agents of multidrug resis-
tance in cancer [2, 3]. Furthermore, there are some reports
about their possible cytotoxic activity. Mainly, some deriva-
tives including dexniguldipine and some dibenzoyl ones
have shown significant cytotoxicity [4, 5]. There are also some
reports on the effects of DHPs on the potentiation of anti-
tumoral and antimetastatic activity of some common cyto-
toxic drugs [6]. This finding revitalized the interest of
Hantzsch esters, first reported by Hantzsch in 1882 [11]
were typically synthesized by the one-pot condensation of an
aldehyde with alkyl acetoacetate and ammonia either in
acetic acid or in alcohol [12]. Improved methods for the
Hantzsch esters synthesis have been achieved by the use of
an autoclave [13] and by microwave irradiation [14, 15]. A
recent work on the thermal solvent free synthesis of
Hantzsch esters has been reported [16]. The next group of
DHPs, acridine-1,8-diones have been synthesized by the reac-
tions of aldehyde with two equivalents of derivatives 1,3-
cyclohexadione and appropriate amines via various methods
Correspondence: Abbas Shafiee, Department of Medicinal Chemistry,
Faculty of Pharmacy and Pharmaceutical Sciences Research Center,
Tehran University of Medical Sciences, Tehran 14176, Iran
E-mail: ashafiee@asms.ac.ir
Fax: þ98-21-66461178
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112
R. Miri et al.
Arch. Pharm. Chem. Life Sci. 2011, 2, 111–118
5
CHO
O
Ar
O
H
R2
4
3
6
1
R3OOC
COOR3
+
R
O
O
2
Reflux in benzene
O
O
6/
3
5/
4/
1/
2/
N
H
R
R1
R1
N
R
4
5a-m
3/
NH2
OH
Hantzsch esters
Acridines
Ammonium acetate
Figure 1. Structure of Hantzsch esters and acridines.
°
C
200-210
Heat
O
O
O
O
°
200-220 C
2
1
[17]. Asymmetrical acridines have been reported less than
symmetrical acridinones, which contain two identical cyclo-
hexadione rings fused to the DHP [18].
10
11
9
11a
Moreover, 4-hydroxycoumarin constitutes the structural
nucleus of many natural products, drugs and pesticides [19–
21]. It is the key intermediate for various widely used oral anti-
coagulants and rodenticides [22]. Moreover, some natural and
synthetic derivatives of coumarins have demonstrated prom-
ising cytotoxic activity [23, 24]. These findings together with
our interest in 1,4-dihydropyridines [25], prompted us to syn-
thesize and study the cytotoxicity of some new DHPs hetero-
analogues in which one of the 1,3-cyclohexadiones is replaced
by a coumarin ring leading to the chromeno[4,3-b]quinoline or
7-aryl-8,9,10,12-tetrahydro-7H-chromeno[4,3-b]quinoline-6,11-
dione (6a–m). Additionally, the calcium channel antagonistic
activity of the DHP derivatives was examined due to the
known potential Ca2þ channel blocking activity of these
molecules.
12
8
HN
12a
O
7a
1
H
1a
14
2
7
13
6a
15
R
3
6
O
O
18
4a
4
5
16
17
6a-m
Scheme 1. Preparation of chromeno[4,3-b]quinoline 6a–m.
chromatography and were characterized by 1H-NMR, FT-IR,
and EI-MS experiments. The 1H-1H shift COSY, HSQC, and
HMBC of one of the product 6c, were performed to establish
the interfragment relationship and to assign the proton and
carbon signals of compound 6 as shown in Scheme 1. This
structure also correlated with 1H-NMR experiments that have
a singlet associated with the C7-H between d 4.8–5.1 ppm and
multiple signals between d 6.7–8.3 ppm and d 1.8–2.9 ppm
corresponding to aromatic and aliphatic protons. A broad
Chemistry
1
Scheme 1 outlines the synthetic pathway followed for the
synthesis of the desired new ring system. 4-Aminocoumarin
was obtained in 90% yield by melting 4-hydroxycoumarin in the
presence of excess ammonium acetate for 30 min. This method
compared to the ones using boiling acetic acid or ethoxyethanol
has more yields and needs less time [26–29]. It seems 4-amino-
coumarin was converted to 4-hydroxycoumarin in the presence
of both solvents and heating, making to decrease yield.
Condensation of 1,3-cyclohexadione 3 and arylaldehydes 4,
in boiling dry benzene for 5 h yielded the 2-benzylidene-cyclo-
hexane-1,3-dione derivatives 5a–m (80–90%). These compounds
signal between d 9.6–9.7 ppm in the H-NMR spectra and a
strong absorption band at 3200–3300 cmꢀ1 in FT-IR analysis
confirmed the secondary amine functional group.
The IR spectrum of product 6 showed a strong peak at 1701–
1720 cmꢀ1which is typical for a coumarin carbonyl group. A
mechanism for the formation of 6a–m is outlined in Scheme 2.
The Micheal addition of 4-aminocoumarin 2 with a,b unsatu-
rated ketones 5a–m give the intermediates A. Isomerization of
A to B followed by intermolecular cycloadditions and sub-
sequent dehydrations afford compounds 6a–m.
were characterized by 1H-NMR and EI-MS experiments [18]. The Results and discussion
reaction of 4-aminocoumarin 2 with 2-benzylidene-cyclohex-
ane-1,3-dione derivatives (5a–m) proceeded in solvent free sys-
tem at 200–2208C, affording 7-aryl-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6a–m) in 30–50% yield
after completion monitoring by TLC (Scheme 1).
Pharmacology
The in vitro calcium channel antagonist activities of novel
derivatives were evaluated and their IC30 and IC50 values were
calculated. IC30 and IC50 values were defined as the molar
concentration of the test compounds required producing 30
or 50% inhibition of guinea pig ileal longitudinal smooth
muscle (GPLISM) contractions. Results are summarized in
the Table 1.
In our protocol, no organic solvents or additives were used
during the reaction process. The crude products were solid
and the work up procedure was just washing by acetone.
Desired products of high purity were obtained by column
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Arch. Pharm. Chem. Life Sci. 2011, 2, 111–118
Cytotoxicity of Novel Chromeno[4,3-b]quinoline Derivatives
113
NH2
-H+
O
O
O
O
O
+
+ NH2
CH
O
O
CH
2
Ar
O
R
A
5a-m
O
O
O
HO
HN
NH2
O
O
CH
O
H
HN
CH
CH
Ar
Ar
Ar
Scheme 2. Possible mechanism pathway for
the formation of 6.
O
O
O
O
B
6a-m
These compounds demonstrated weak calcium channel
As the Ca2þ-channel antagonist activity was evaluated as an
undesired effect for these compounds; their much
lower activity in comparison with nifedipine would be a
positive point in the future designs of similar
derivatives.
antagonist activities (IC50 ¼ 10ꢀ4–10ꢀ7 M) compared to the
reference drug nifedipine (IC50 ¼ 9.14 ꢁ 10ꢀ8 M). The most
active compound 6f, which is at least 3 folds stronger
than the others, is nearly 7 times weaker than nifedipine.
Table 1. Physical properties of compounds 6a–m and their calcium channel antagonist activity assessed in the ileum of guinea-pigs.
R
O
O
O
N
H
Compound
R
M. p.
Yield (%)
Formula
IC30 (Mean ꢂ SE)a
IC50 (Mean ꢂ SE)a
N
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
2-nitro
4-nitro
>300
260–262
267–269
294–296
>310
208–210
214–216
>310
280–281
276–278
188–190
310
304–305
–
35
45
60
65
50
50
55
75
55
75
45
74
72
–
C22H16N2O5
C22H16N2O5
(7.07 ꢂ 5.03) ꢁ 10ꢀ5
(2.96 ꢂ 1.33) ꢁ 10ꢀ6
(2.79 ꢂ 1.73) ꢁ 10ꢀ6
(7.69 ꢂ 4.82) ꢁ 10ꢀ7
(6.06 ꢂ 2.12) ꢁ 10ꢀ6
(8.69 ꢂ 7.11) ꢁ 10ꢀ8
(1.39 ꢂ 0.91) ꢁ 10ꢀ6
(5.30 ꢂ 3.58) ꢁ 10ꢀ6
Inactive
(6.36 ꢂ 6.13) ꢁ 10ꢀ8
(9.16 ꢂ 5.21) ꢁ 10ꢀ6
(4.10 ꢂ 2.96) ꢁ 10ꢀ6
(2.97 ꢂ 0.70) ꢁ 10ꢀ6
(1.49 ꢂ 0.83) ꢁ 10ꢀ8
(8.00 ꢂ 6.00) ꢁ 10ꢀ4
(7.55 ꢂ 2.17) ꢁ 10ꢀ6
(6.55 ꢂ 4.20) ꢁ 10ꢀ6
(2.29 ꢂ 1.03) ꢁ 10ꢀ6
(9.50 ꢂ 3.34) ꢁ 10ꢀ6
(5.99 ꢂ 4.00) ꢁ 10ꢀ7
(3.23 ꢂ 1.57) ꢁ 10ꢀ6
(2.00 ꢂ 2.00) ꢁ 10ꢀ4
Inactive
(1.83 ꢂ 1.79) ꢁ 10ꢀ6
(4.99 ꢂ 3.78) ꢁ 10ꢀ5
(1.02 ꢂ 0.48) ꢁ 10ꢀ5
(8.93 ꢂ 1.48) ꢁ 10ꢀ6
(9.14 ꢂ 4.83) ꢁ 10ꢀ8
3
3
3
3
4
2
3
5
2
2
4
3
4
4
3-bromo
4-bromo
2-chloro
3-chloro
4-chloro
2-methoxy
3-methoxy
4-methoxy
2-methyl
3-methyl
4-methyl
–
C22H16BrNO3
C22H16BrNO3
C22H16ClNO3
C22H16ClNO3
C22H16ClNO3
C23H19NO4
C23H19NO4
C23H19NO4
C23H19NO3
C23H19NO3
C23H19NO3
C19H22N2O6
6l
6m
Nifedipine
a
Molar concentration.
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114
R. Miri et al.
Arch. Pharm. Chem. Life Sci. 2011, 2, 111–118
Table 2. Cytotoxic activity of synthetic compounds assessed by the MTT reduction assay.
Compound
IC50 (mM)
HeLa
K562
LS180
MCF-7
6a
6b
6c
6d
29.8 ꢂ 7.7
88.2 ꢂ 35.4
83.6 ꢂ 18.9
47.3 ꢂ 11.1
>100
25.4 ꢂ 4.4
43.8 ꢂ 8.6
38.8 ꢂ 4.3
47.5 ꢂ 9.6
>100
>100
>100
>100
>100
>100
58.6 ꢂ 14.1
>100
31.4 ꢂ 9.8
46.2 ꢂ 10.5
>100
6e
6f
6g
6h
6i
6j
6k
6l
6m
>100
37.7 ꢂ 11.0
50.7 ꢂ 10.0
37.5 ꢂ 5.1
>100
>100
>100
>100
>100
>100
>100
>100
>100
71.7 ꢂ 17.0
41.8 ꢂ 10.1
>100
>100
>100
>100
>100
>100
>100
62.0 ꢂ 20.4
98.5 ꢂ 74.9
>100
>100
>100
57.4 ꢂ 10.9
56.2 ꢂ 23.8
0.137 ꢂ 0.045
52.2 ꢂ 12.6
66.7 ꢂ 16.6
0.180 ꢂ 0.031
43.6 ꢂ 15.0
Doxorubicin
0.256 ꢂ 0.057
0.157 ꢂ 0.117
Values represent the mean ꢂ S.D. of 3 to 4 different experiments.
Cytotoxicity activity
cells did not show a strong correlation. These correlations
may be a sign of possible similar cytotoxic mechanisms on
different cancer cell lines that we used in this study. On the
other hand, we did not find any significant correlation
between the cytotoxic activity and the calcium channel
antagonist action of the synthetic compounds.
The cytotoxic activity of synthesized compounds was eval-
uated in 4 human cancer cell lines and the data are demon-
strated in Table 2. The lowest activity was observed over LS180
cells, since the IC50 values of all compounds were higher than
100 mM in this cell line. Compounds seemed to have similar
effects on the other 3 cell lines (HeLa, K562, and MCF-7).
Among these compounds, 7-(2-nitrophenyl)-8,9,10,12-tetrahy-
dro-7H-chromeno[4,3-b]quinoline-6,8-dione (6a) was the most
potent derivative with an IC50 range of 25–58 mM. Although,
7-(4-chlorophenyl)-8,9,10,12-tetrahydro-7H-chromeno[4,3-b]
quinoline-6,8-dione (6g) showed to some extent similar
activity (IC50: 37–41 mM). On the other hand, four com-
pounds, 6e, 6h, 6i, and 6k, were the weakest ones showing
no activity at concentrations lower than 100 mM.
Conclusion
In this study, we synthesized 15 new compounds having the
features of 1,4-dihydropyridines and 4-hydroxycoumarins and
tested for their cytotoxic activity on human cancer cell lines.
Some of these derivatives showed moderate cytotoxic capacity
and at the same time very low calcium channel antagonist
activity, an undesirable effect when these compounds are used
as antitumoral agents. This group of compounds seems to have
promising properties and further investigation on this group
could potentially lead to the discovery of potent cytotoxic
agents with low calcium channel blocking activity.
A survey on the basis of changing moieties showed that the
methoxy group confers the lowest cytotoxic activity, since
compounds 6h and 6i were among the weakest derivatives.
Interestingly, the analysis of the correlation between cyto-
toxic activity in different cell lines demonstrated clear
relationship between cytotoxic efficiency of these com-
pounds in various cell lines (Table 3); HeLa and K562 data
had the best correlation, while IC50 values of HeLa and MCF-7
Experimental
General
All chemicals and all solvents used in this study were purchased
from Merck Company (Darmstadt, Germany) and Sigma-Aldrich
Chemical Company (Steinhein, Germany). RPMI 1640, fetal
bovine serum (FBS), trypsin and phosphate buffered saline
(PBS) were purchased from Biosera (Ringmer, UK). Doxorubicin
was obtained from EBEWE Pharma (Unterach, Austria). Melting
points were determined on a Kofler hot stage apparatus
(Reichert, Vienna, Austria) and are uncorrected. 1H-NMR spectra
were measured using a Bruker 500 spectrometer (Bruker,
Rheinstetten, Germany) and chemical shifts are expressed as d
(ppm) with tetramethylsilane as internal standard. The IR spectra
Table 3. Correlation coefficients (R2) between IC50 values of
synthesized compounds obtained by the MTT assay in various cell
lines and Ca channel antagonist activity (CCA).
HeLa
K562
MCF-7
CCA
HeLa
K562
MCF-7
CCA
1
0.720
0.471
0.246
1
0.640
S0.289
1
0.061
1
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Arch. Pharm. Chem. Life Sci. 2011, 2, 111–118
Cytotoxicity of Novel Chromeno[4,3-b]quinoline Derivatives
115
were acquired on a Nicollet FT-IR magna 550 spectrographs (KBr
disks) (Nicollet, Madison, WI, USA). MS spectra were obtained
with a Finnegan MAT TSQ-70 spectrometer (Finnegan Mat,
Bremen, Germany). The purity of a compound was confirmed
by TLC using different mobile phases. The results of elemental
analyses (C, H, N) were within ꢂ0.4% of theoretical values for C,
H, and N.
NH). 13C-NMR (DMSO-d6): d 20.69 (C10), 26.59 (C9), 35.02 (C7),
36.56 (C11), 95.4–100.6 (C12a, C6a), 110.93 (C1a, C7a), 116.93 (C4),
123.22–123.30 (C15, C17, C1), 124.06 (C2), 129.14 (C14, C18), 132.19
(C3), 145.92 (C13), 152.19 (C4a, C1a), 153.27 (C16), 160.29 (C6), 194.87
(C8). EI-MS: m/z (%), 389 (Mþ þ 1, 30), 388 (Mþ, 10), 370 (17), 342
(22), 267 (100), 149 (15), 83 (30). Anal. calcd. for C22H16N2O5: C,
67.04; H, 4.15; N, 7.21. Found: C, 67.26; H, 4.34; N, 7.03.
4-Aminocoumarin (2)
7-(3-Bromophenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6c)
A mixture of 4-hydroxycoumarin 1 (1 mmol) and ammonium
acetate (2 mmol) were stirred after melting 4-hydroxycoumarin
in 2118C for 30 min to complete the reaction (monitored by TLC),
then cooled to room temperature. The crude was washed with
ethyl acetate and dried in vacuo to give the pure compound 2, a
colorless solid (90%). Mp 232–2338C, reported 232–2348C [26].
Yield 60%: m.p. 267–2698C. IR (KBr) cmꢀ1: n 3436 (NH), 3078 (C–H
1
–
aromatic), 2924 (C–H aliphatic), 1671 (C O). H-NMR (DMSO-d ): d
–
6
1.88–1.99 (m, 2H, H10), 2.24–2.40 (m, 2H, H11), 2.51–2.81 (m,
1H, H9), 2.83–2.89 (m, 1H, H9), 4.97 (s, 1H, H7), 7.18–7.41 (m,
5H, H4, H14, H16, H17, H18), 7.46 (t, 1H, J ¼ 8.0 Hz, H2), 7.64 (t, 1H,
J ¼ 8.0 Hz, H3), 8.33 (d, 1H, J ¼ 8.0 Hz, H1), 9.95 (s, 1H, NH). EI-MS:
m/z (%), 423 (Mþ þ 2, 24), 421 (Mþ, 25), 342 (34), 267 (100), 144
(20), 76 (8), 56 (15). Anal. calcd. for C22H16BrNO3: C, 62.57; H, 3.82;
N, 3.32. Found: C, 62.38; H, 3.96; N, 3.54.
Typical procedure for the preparation of 2-benzylidene-
cyclohexane-1,3-dione derivatives (5a–m)
A mixture of 1,3-cyclohexadione 3 (1 mmol) and arylaldehyde 4
(1.0 mmol) were refluxed in dry benzene (50 mL) for 5 h. The
mixture was cooled to room temperature and the solvent was
evaporated to dryness under reduced pressure, and the crude
product was washed with cold ethyl acetate and dried in vacuo to
give pure product 5 (70–90% yield). The products are known
compounds and were identified by comparison of spectral and
physical data [18].
7-(4-Bromophenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6d)
Yield 65%: m.p. 294–2968C. IR (KBr) cmꢀ1: n 3334 (NH), 3025 (C–H
1
–
aromatic), 2934 (C–H aliphatic), 1675 (C O). H-NMR (DMSO-d ) d:
–
6
1.84–1.89 (m, 1H, H10), 1.97–2.02 (m, 1H, H10), 2.24–2.31 (m, 2H, H11),
2.65–2.72 (m, 1H, H9), 2.80–2.85 (m, 1H, H9), 4.95 (s, 1H, H7), 7.18 (d,
2H, J ¼8.5 Hz, H14, H18), 7.36 (d, 2H, J ¼ 8.5 Hz, H15, H17), 7.41 (dd,
1H, J ¼ 8.0, 1.0 Hz, H4), 7.45 (td, 1H, J ¼8.0, 1.0 Hz, H2), 7.64 (td, 1H,
J ¼ 8.0, 1.5 Hz, H3), 8.33 (dd, 1H, J ¼ 8.0, 1.5 Hz, H1), 9.79 (s, 1H, NH).
EI-MS: m/z (%), 423 (Mþ þ 2, 15), 422 (Mþ, 15), 266 (100), 211 (25), 155
(38), 56 (27). Anal. calcd. for C22H16BrNO3: C, 62.57; H, 3.82; N, 3.32.
Found: C, 62.76; H, 3.95; N, 3.14.
General procedure for the preparation of 7-aryl-8,9,10,12-
tetrahydro-7H-chromeno[4,3-b]quinoline-6,8-dione (6a–m)
4-Aminocoumarin 2 (1mmol) and 2-benzylidene-cyclohexane-1,3-
dione derivatives 5a–m (1 mmol) were thoroughly mixed in a
beaker using spatula. Then the beaker is placed in an autoclave
(200–2208C) for 45 min to complete the reaction (monitored by
TLC). The solid crude was washed with acetone (50 mL) and
purified by column chromatography using ethyl acetate/
petroleum ether (20:80) to give 6.
7-(2-Chlorophenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6e)
Yield 50%: m.p. >3108C. IR (KBr) cmꢀ1: n 3370 (NH), 3067 (C–H
1
–
aromatic), 2934 (C–H aliphatic), 1685 (C O). H-NMR (DMSO-d ) d:
–
6
1.84–1.86 (m, 1H, H10), 1.95–1.99 (m, 1H, H10), 2.24–2.30 (m,
2H, H11), 2.63–2.69 (m, 1H, H9), 2.78–2.84 (m, 1H, H9), 5.21 (s,
1H, H7), 7.07 (t, 1H, J ¼ 7.6 Hz, H16), 7.14 (t, 1H, J ¼ 7.6 Hz, H17),
7.20 (d, 1H, J ¼ 7.6, H18), 7.32 (m, 2H, H4, H15), 7.40 (t, 1H,
8.0 Hz, H2), 7.60 (t, 1H, J ¼ 8.0 Hz, H3), 8.29 (d, 1H,
J ¼ 8.0 Hz, H1), 9.85 (s, 1H, NH). EI-MS: m/z (%), 379 (Mþ þ 2,
8), 377 (Mþ, 25), 342 (23), 266 (100), 56 (25). Anal. calcd.
for C22H16ClNO3: C, 69.94; H, 4.27; N, 3.71. Found: C, 69.75; H,
4.09; N, 3.53.
7-(2-Nitrophenyl)-8,9,10,12-tetrahydro-7H-chromeno
[4,3-b]quinoline-6,8-dione (6a)
Yiled 35%: m.p. >3008C. IR (KBr) cmꢀ1: n 3313 (NH), 3088 (C–H
1
aromatic), 2945 (C–H aliphatic), 1670 (C O), 1526, 1352 (NO ). H-
–
–
2
NMR (DMSO-d6): d 2.05–2.14 (m, 2H, H10), 2.43–2.40 (m, 2H, H11),
2.72–2.79 (m, 1H, H9), 2.83–2.89 (m, 1H, H9), 5.75 (s, 1H, H7), 7.39
(d, 1H, J ¼ 8.0 Hz, H4), 7.49 (t, 1H, J ¼ 8.0 Hz, H2), 7.54 (t, 1H,
J ¼ 8.0 Hz, H16), 7.64–7.73 (m, 3H, H17, H18, H3), 8.00 (d, 1H,
J ¼ 8.0 Hz, H15), 8.35 (d, 1H, J ¼ 8.0 Hz, H1), 9.90 (s, 1H, NH).
EI-MS: m/z (%), 388 (Mþ, 51), 358 (34), 342 (17), 266 (100), 228 (74),
146 (20), 126 (40), 70 (48). Anal. calcd. for C22H16N2O5: C, 67.04; H,
4.15; N, 7.21. Found: C, 67.28; H, 4.02; N, 7.45.
7-(3-Chlorophenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6f)
Yield 50%: m.p. 208–2108C. IR (KBr) cmꢀ1: n 3324 (NH), 3073 (C–H
1
7-(4-Nitrophenyl)-8,9,10,12-tetrahydro-7H-chromeno
[4,3-b]quinoline-6,8-dione (6b)
–
aromatic), 2939 (C–H aliphatic), 1675 (C O). H-NMR (DMSO-d ): d
–
6
1.83–1.99 (m, 2H, H10), 2.25–2.32 (m, 2H, H11), 2.62–2.72 (m,
1H, H9), 2.82–2.89 (m, 1H, H9), 4.97 (s, 1H, H7), 7.11–7.27 (m,
4H, H14, H16, H17, H18), 7.39 (d, 1H, J ¼ 8.0 Hz, H4), 7.45 (t, 1H,
J ¼ 8.0 Hz, H2), 7.65 (t, 1H, J ¼ 8.0 Hz, H3), 8.33 (d, 1H,
J ¼ 8.0 Hz, H1), 9.82 (s, 1H, NH). EI-MS: m/z (%), 379 (Mþ þ 2,
2), 377 (Mþ, 7), 342 (30), 266 (100), 111 (10), 56 (5). Anal. calcd.
for C22H16ClNO3: C, 69.94; H, 4.27; N, 3.71. Found: C, 70.15; H,
4.49; N, 3.52.
Yield 45%: m.p. 260–2628C. IR (KBr) cmꢀ1: n 3336 (NH), 3100 (C–H
1
aromatic), 2934 (C–H aliphatic), 1685 (C O), 1520, 1362 (NO ). H-
–
–
2
NMR (DMSO-d6): d 1.83–2.02 (m, 2H, H10), 2.20–2.43 (m, 2H, H11),
2.72–2.79 (m, 1H, H9), 2.83–2.87 (m, 1H, H9), 5.10 (s, 1H, H7), 7.39
(d, 1H, J ¼ 8.0 Hz, H4), 7.45 (t, 1H, J ¼ 8.0 Hz, H2), 7.52 (d, 2H,
J ¼ 9.0 Hz, H14, H18), 7.65 (t, 1H, J ¼ 8.0 Hz, H3), 8.08 (d, 1H,
J ¼ 9.0 Hz, H15, H17), 8.34 (d, 2H, J ¼ 8.0 Hz, H1), 9.90 (s, 1H,
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Arch. Pharm. Chem. Life Sci. 2011, 2, 111–118
7.07 (d, 1H, J ¼ 7.5 Hz, H18), 7.29 (t, 1H, J ¼ 7.5 Hz, H16), 7.34 (d,
1H, J ¼ 8.0 Hz, H4), 7.43 (t, 1H, J ¼ 8.0 Hz, H2), 7.60 (t, 1H,
J ¼ 8.0 Hz, H3), 8.31 (d, 1H, J ¼ 8.0 Hz, H1), 9.67 (s, 1H, NH). EI-
MS: m/z (%), 357 (Mþ, 21), 342 (15), 266 (100), 224 (32), 196 (10).
Anal. calcd. for C23H19NO3: C, 77.29; H, 5.36; N, 3.92. Found: C,
77.48; H, 5.08; N, 4.15.
7-(4-Chlorophenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6g)
Yield 55%: m.p. 214–2168C. IR (KBr) cmꢀ1: n 3390 (NH), 3206 (C–H
1
–
aromatic), 2939 (C–H aliphatic), 1675 (C O). H-NMR (DMSO-d ): d
–
1.86–1.87 (m, 1H, H10), 1.97–2.01 (m, 1H, H10), 2.26–2.31 (m,
6
2H, H11), 2.65–2.71 (m, 1H, H9), 2.80–2.85 (m, 1H, H9), 4.97 (s,
1H, H7), 7.12 (d, 2H, J ¼ 8.5 Hz, H14
, H18), 7.30 (d, 2H,
7-(3-Methylphenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6l)
J ¼8.5 Hz, H15, H17), 7.36 (d, 1H, J ¼ 8.0 Hz, H4), 7.43 (t, 1H,
J ¼ 8.0 Hz, H2), 7.63 (t, 1H, J ¼ 8.0 Hz, H3), 8.30 (d, 1H,
J ¼ 8.0 Hz, H1), 9.77 (s, 1H, NH). EI-MS: m/z (%), 379 (Mþ þ 2,
17), 377 (Mþ, 41), 344 (15), 321 (30), 266 (100), 216 (75), 112
(65), 68 (38). Anal. calcd. for C22H16ClNO3: C, 69.94; H, 4.27; N,
3.71. Found: C, 69.73; H, 4.48; N, 3.95.
Yield 74%: m.p. 3108C. IR (KBr) cmꢀ1: n 3339 (NH), 3052 (C–H
1
–
aromatic), 2909 (C–H aliphatic), 1680 (C O). H-NMR (DMSO-d ): d
–
6
1.84–1.88 (m, 1H, H10), 1.98–2.01 (m, 1H, H10), 2.20 (s, 3H, CH3),
2.24–2.31 (m, 2H, H11), 2.65–2.72 (m, 1H, H9), 2.80–2.85 (m,
1H, H9), 4.95 (s, 1H, H7), 6.89 (d, 1H, J ¼ 8.0 Hz, H16), 6.98 (d,
1H, J ¼ 8.0 Hz, H18), 7.03 (s, 1H, H14), 7.07 (d, 1H, J ¼ 8.0 Hz, H17),
7.36 (d, 1H, J ¼ 8.0 Hz, H4), 7.41 (t, 1H, J ¼ 8.0 Hz, H2), 7.63 (t, 1H,
J ¼ 8.0 Hz, H3), 8.31 (d, 1H, J ¼ 8.0 Hz, H1). EI-MS: m/z (%), 357
(Mþ, 5), 266 (100), 224 (23), 111 (45), 196 (40). Anal. calcd.
for C23H19NO3: C, 77.29; H, 5.36; N, 3.92. Found: C, 77.06; H,
5.53; N, 3.75.
7-(2-Methoxyphenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6h)
Yield 75%: m.p. >3108C. IR (KBr) cmꢀ1: n 3359 (NH), 3053 (C–H
1
–
aromatic), 2863 (C–H aliphatic), 1670 (C O). H-NMR (DMSO-d ): d
–
6
1.76–1.79 (m, 1H, H10), 1.93–1.95 (m, 1H, H10), 2.10–2.23 (m,
2H, H11), 2.54–2.65 (m, 1H, H9), 2.72–2.75 (m, 1H, H9), 3.63 (s,
3H, CH3), 5.06 (s, 1H, H7), 6.7 (t, 1H, J ¼ 8.0 Hz, H17), 6.85 (d, 1H,
J ¼ 8.0 Hz, H15), 7.06 (td, 1H, J ¼ 8.0, 1.5 Hz, H16), 7.23 (dd, 1H,
J ¼ 8.0, 1.5 Hz, H18), 7.32 (d, 1H, J ¼ 8.0 Hz, H4), 7.41 (t, 1H,
J ¼ 8.0 Hz, H2), 7.59 (t, 1H, J ¼ 8.0 Hz, H3), 8.30 (d, 1H,
J ¼ 8.0 Hz, H1), 9.68 (s, 1H, NH). EI-MS: m/z (%), 373 (Mþ, 36), 342
(10), 266 (100), 167 (25), 87 (30), 56 (12). Anal. calcd. for C23H19NO4:
C, 73.98; H, 5.13; N, 3.75. Found: C, 74.15; H, 5.01; N, 3.57.
7-(4-Methylphenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6m)
Yield 72%: m.p. 304–3058C. IR (KBr) cmꢀ1: n 3272 (NH), 3062 (C–H
1
–
aromatic), 2950 (C–H aliphatic), 1710 (C O). H-NMR (DMSO-d ): d
–
6
1.82–1.88 (m, 1H, H10), 1.98–2.03 (m, 1H, H10), 2.17 (s, 3H, CH3),
2.15–2.34 (m, 2H, H11), 2.72 (m, 1H, H9), 2.80–2.85 (m, 1H, H9),
4.94 (s, 1H, H7), 7.00 (d, 2H, J ¼ 8.0 Hz, H15, H17), 7.11 (d, 2H,
J ¼ 8.0 Hz, H14, H18), 7.37 (d, 1H, J ¼ 8.0 Hz, H4), 7.43 (t, 1H,
J ¼ 8.0 Hz, H2), 7.62 (t, 1H, J ¼ 8.0 Hz, H3), 8.29 (d, 1H,
J ¼ 8.0 Hz, H1), 9.73 (s, 1H, NH). EI-MS: m/z (%), 357 (Mþ, 8),
343 (50), 266 (100), 224 (25), 83(23), 65 (35). Anal. calcd.
for C23H19NO3: C, 77.29; H, 5.36; N, 3.92. Found: C, 77.43; H,
5.18; N, 3.76.
7-(3-Methoxyphenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6i)
Yield 55%: m.p. 280–2818C. IR (KBr) cmꢀ1: n 3324 (NH), 3100 (C–H
1
–
aromatic), 2945 (C–H aliphatic), 1670 (C O). H-NMR (DMSO-d ): d
–
6
1.46–1.57 (m, 1H, H10), 1.59–1.65 (m, 1H, H10), 2. 05–2.24 (m,
2H, H11), 2.48–2.59 (m, 1H, H9), 2.67–2.70 (m, 1H, H9), 3.68 (s, 3H,
CH3), 4.97 (s, 1H, H7), 6.68 (d, 1H, J ¼ 7.5 Hz, H18), 6.76–6.79 (m,
2H, H14, H16), 7.11 (t, 1H, J ¼ 7.5 Hz, H17), 7.29 (d, 1H, J ¼ 8.0 Hz, H4),
7.43 (t, 1H, J ¼ 8.0 Hz, H2), 7.58 (t, 1H, J ¼ 8.0 Hz, H3), 8.30 (d, 1H,
J ¼ 8.0 Hz, H1), 9.77 (s, 1H, NH). EI-MS: m/z (%), 373 (Mþ, 45), 342 (22),
266 (100), 93 (85), 76 (50). Anal. calcd. for C23H19NO4: C, 73.98; H,
5.13, N, 3.75. Found: C, 73.72; H, 5.35; N, 3.56.
Pharmacology
Calcium channel antagonist activity
Male albino guinea pigs (300–450 g) were purchased from
Animal House Department of the Shiraz University of
Medical Sciences. They had free access to standard rodent
chow and tap water. The animals were housed in a room
maintained at 23 ꢂ 28C, 55 ꢂ 10% of humidity, and on a
12 h dark/light cycle. Feeding was stopped one day before
starting the in-vitro tests. Guinea pigs were sacrificed and
their intestines were removed above the ileocecal junction.
Smooth muscle segments of about 1 cm length were
mounted under a resting tension of 500 mg and were main-
tained at 378C in a 20 mL jacketed organ bath containing
oxygenated (95% O2 and 5% CO2) physiological saline solution
of the following compositions: 137 mM NaCl, 1.8 mM CaCl2,
2.7 mM KCl, 1.1 mM MgSO4, 0.4 mM NaHPO4, 12 mM
NaHCO3, and 5 mM glucose. The muscle was equilibrated
for 1 h with a solution changing every 15 min. The contrac-
tions were recorded with a forced displacement transducer
7-(4-Methoxyphenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6j)
Yield 75%: m.p. 276–2788C. IR (KBr) cmꢀ1: n 3441 (NH), 3073 (C–H
1
–
aromatic), 2934 (C–H aliphatic), 1670 (C O). H-NMR (DMSO-d ): d
–
6
1.92–2.04 (m, 2H, H10), 2.35–2.41 (m, 2H, H11), 2.45–2.55 (m, 1H, H9),
2.56–2.63 (m, 1H, H9), 3.64 (s, 3H, CH3), 5.25 (s, 1H, H7), 6.68 (d, 2H,
J ¼ 8.5 Hz, H15, H17), 7.23–7.27 (m, 2H, H4, H2),7.30 (d, 2H,
J ¼ 8.5 Hz, H14, H18), 7.50 (t, 1H, J ¼ 7.5 Hz, H3), 7.86 (d, 1H,
J ¼ 7.5 Hz, H1), 8.28 (s, 1H, NH). EI-MS: m/z (%), 373 (Mþ, 25),
266 (100), 211 (10), 77 (10). Anal. calcd. for C23H19NO4: C, 73.98;
H, 5.13, N, 3.75. Found: C, 73.76; H, 5.02; N, 3.96.
7-(2-Methylphenyl)-8,9,10,12-tetrahydro-7H-
chromeno[4,3-b]quinoline-6,8-dione (6k)
Yield 45%: m.p. 188–1908C. IR (KBr) cmꢀ1: n 3405 (NH), 3057 (C–H
1
–
aromatic), 2929 (C–H aliphatic), 1700 (C O). H-NMR (DMSO-d ): d
–
1.81–1.97 (m, 2H, H10), 2.18–2.27 (m, 2H, H11), 2.50 (s, 3H, CH3),
6
2.65–2.90 (m, 2H, H9), 5.03 (s, 1H, H7), 6.94–6.99 (m, 2H, H15, H17),
(Hugo Sachs, March-Hugstetten and Germany) on
a
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Arch. Pharm. Chem. Life Sci. 2011, 2, 111–118
Cytotoxicity of Novel Chromeno[4,3-b]quinoline Derivatives
117
This work was supported by research council of Tehran University of
Medical Sciences, and INSF (Iran National Sciences Foundation).
Financial support of the Research Council of Shiraz University of
Medical Sciences is also acknowledged.
physiograph (Hugo Sachs). All compounds were dissolved in
DMSO and the same volume of solvent was used as the
negative control. Nifedipine was used as the positive control.
The contraction was elicited with 80 mM KCl. The contractile
response was taken as the 100% value for the tonic (slow)
component of the response. Test compounds were added in
cumulative doses after the dose response for KCl. Test com-
pound-induced relaxation of contracted muscle was
expressed as the percent of inhibition of the control. The
IC50 values were determined from the concentration–
response curves [30, 31].
The authors have declared no conflict of interest.
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