Synthesis and biological evaluation of 1,9-disubstituted β-carbolines as potent DNA intercalating and cytotoxic agents

Article abstract of DOI:10.1016/j.ejmech.2011.08.027

A series of novel 1,9-disubstituted β-carbolines was designed, synthesized and evaluated as cytotoxic and DNA intercalating agents. Compounds 7b, 7c, 8b and 8c exhibited the most potent cytotoxic activities with IC ₅₀ values of lower than 20 μM against ten human tumor cell lines. The results indicated that (1) the 3-chlorobenzyl and 3-phenylpropyl substituents in position-9 of β-carboline nucleus were the suitable pharmacophoric group giving rise to significant antitumor agents; (2) the length of the alkylamino side chain moiety affected their cytotoxic potencies, and three CH₂ units were more favorable. In addition, these compounds were found to exhibit remarkable DNA intercalating effects.

Full text of DOI:10.1016/j.ejmech.2011.08.027

European Journal of Medicinal Chemistry 46 (2011) 5127e5137
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European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and biological evaluation of 1,9-disubstituted
DNA intercalating and cytotoxic agents
b-carbolines as potent
,
b
c
c
c
c
b,
*
Zhiyong Chen a, Rihui Cao b , Buxi Shi , Liang Guo , Jie Sun , Qin Ma , Wenxi Fan , Huacan Song
*
a Guangdong Provincial Public Laboratory of Analysis and Testing Technology, China National Analytical Center, Building 34, 100 Xianlie Middle Road, Guangzhou, 510070, PR China
b School of Chemistry and Chemical Engineering, Sun Yat-sen University, 135 Xin Gang West Road, Guangzhou 510275, PR China
c Xinjiang Huashidan Pharmaceutical Co. Ltd., 45 He Nan East Road, Urumqi 830011, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of novel 1,9-disubstituted b-carbolines was designed, synthesized and evaluated as cytotoxic and
Received 13 February 2010
Received in revised form
15 August 2011
Accepted 19 August 2011
Available online 26 August 2011
DNA intercalating agents. Compounds 7b, 7c, 8b and 8c exhibited the most potent cytotoxic activities
with IC50 values of lower than 20 M against ten human tumor cell lines. The results indicated that (1)
the 3-chlorobenzyl and 3-phenylpropyl substituents in position-9 of -carboline nucleus were the
suitable pharmacophoric group giving rise to significant antitumor agents; (2) the length of the alky-
lamino side chain moiety affected their cytotoxic potencies, and three CH2 units were more favorable. In
addition, these compounds were found to exhibit remarkable DNA intercalating effects.
Ó 2011 Elsevier Masson SAS. All rights reserved.
m
b
Keywords:
b
-Carboline
Synthesis
Cytotoxic
Intercalating
Tm
1. Introduction
[7,14,15], CDK [16e18], MK-2 [19,20], PLK1 [21], kinesin Eg5 [22]
and IKK [19].
DNA is one of the most important pharmacological targets of
many drugs currently in clinical use. Small molecules that bind
genomic DNA have proven to be effective antitumor, antivirus and
antibacterial therapeutic agents. It is well-known that small
molecules can interact with DNA through multiple modes including
(i) intercalation; (ii) surface binding; (iii) minor groove binding and
(iv) major groove binding. DNA intercalating agents form an
important class of drugs in antitumor therapy [1]. To investigate the
interaction of such agents with DNA, in particular, effects of
structural requirement of them on the interaction, could offer novel
insights into the design of new DNA targeting antitumor drugs [2].
To promote the antitumor activity and DNA intercalating
potency of such compounds, previous attempt [5,11] were focused
on incorporating substituents into position-1 and 3 of
nucleus. The introduction of amino group into position-1 or the
presence of a flexible amino side chain in position-3 of -carboline
b-carboline
b
nucleus was proved to improve the affinity of the intercalator for
the DNA molecule, consequently to a greater cytotoxic activity. We
have ever reported that a series of 9-alkyl or arylated alkyl
substituted harmine derivatives as efficient DNA intercalating and
potent cytotoxic agents [23]. In addition, our previous investigation
[24e29] on the synthesis of a variety of
the evaluation of their antitumor activities unraveled that b
b
-carboline derivatives and
-car-
The
b-carboline alkaloids are a large group of natural and
synthetic indole alkaloids associated with a broad spectrum of
biochemical effects and pharmaceutical properties [3]. Recent
bolines had potent antitumor activities and the activities was
correlated to both the planarity of the molecule and the presence of
the ring substituents. Structureeactivity relationships (SARs)
analysis suggested that the introduction of appropriate substitu-
reports [4e12] have pointed out
b-carbolines as a new class of
potential antitumor agents, which were discovered to exert their
antitumor effects through multiple mechanisms of action, such as
intercalating into DNA [5,10,13], inhibiting topoisomerase I and II
ents into position-9 of b-carboline nucleus played a vital role in
determining their antitumor potencies, and the n-butyl and phe-
nylpropyl substituents in position-9 was suitable pharmacophoric
group giving rise to some potent antitumor agents.
More recently, our group reported that
a flexible alkylamino side chain at position-3 and a alkyl or arylated
alkyl substituent at position-9, exhibited significant antitumor
b-carbolines, bearing
* Corresponding authors. Tel.: þ86 20 84110918; fax: þ86 20 84112245.
E-mail addresses: caorihui@mail.sysu.edu.cn (R. Cao), yjhxhc@mail.sysu.edu.cn
(H. Song).
0223-5234/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.08.027

5128
Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
activities in vitro, and the N9-arylated alkyl substituted
represented the most interesting cytotoxic activities [31,32]. In
addition, previous literature described that the complex polycyclic
ring system at postion-1 of b-carboline nucleus in manzamine A
can be replaced with simpler amino substituents to provide active
compounds [11].
b
-carbolines
corresponding carboxaldehyde by SeO2 in anhydrous dioxane to
provide compounds 2aef in 62e78% yield. The reaction of
compounds 2aef with the corresponding diamines to form schiff
bases took place readily at room temperature in good yield. The
crude schiff bases without further purification were directly
reduced with NaBH3CN in anhydrous methanol to give the target
In our continued efforts for simple but efficient antitumor and
DNA intercalating agents, we report here, the molecular design and
chemical synthesis of a series of novel b-carbolines bearing a flex-
ible alkylamino side chain at position-1 and a alkyl or arylated alkyl
substituent at position-9, respectively. These compounds were
expected to intercalate into DNA more strongly and to exhibit
efficient medical and biological use due to the improved water
solubility and the increased flexibility of the aminoalkyl side chains.
b-carbolines 3aed, 4aed, 5aed, 6aed, 7aed and 8aed (Table 1) in
35e65% yield. The chemical structures of all the synthesized new
compounds were characterized by MS, IR, 1H NMR, and 13C NMR
spectra.
3. Results and discussion
3.1. Cytotoxic activity in vitro
2. Chemistry
The cytotoxic potencies of novel b-carbolines bearing a N,N-
dialkylaminoalkylamino moiety against a panel of human tumor
cell lines were investigated and compared with the reference drugs
cisplatin, paclitaxel and adriamycin. The tumor cell line panel
consisted of renal carcinoma (769-P, 786-0 and OS-RC-2), epider-
moid carcinoma of the nasopharynx (KB), gastric carcinoma (BGC-
823), liver carcinoma (HepG2), melanoma (A375), colon carcinoma
(HT-29), prostate carcinoma (22RV1) and breast carcinoma (MCF-
7). As shown in Table 1, compounds 3aed, 4aed, 5aed and 6aed
only demonstrated moderate cytotoxic activities, whereas
The synthetic routes of novel
6aed, 7aed and 8aed are outlined in Scheme 1. The 1-methyl
-carboline, prepared by the condensation of -tryptophan with
b-carbolines 3aed, 4aed, 5aed,
b
L
acetaldehyde in acid solution and followed by aromatization,
oxidation and decarboxylation in a single step through the action of
potassium dichromate according to the method previously
described by Synder et al. [30], was alkylated or arylated by the
action of sodium hydride in anhydrous DMF followed by the
addition of the relevant appropriate alkylating and arylating agents
to afford intermediates 1aef [24e26] in 65e76% yield. The methyl
group in position-1 of compounds 1aef was oxidized to its
compounds 7aed and 8aed, bearing
3-phenylpropyl substituents in position-9 of
respectively, exhibited significant cytotoxic potencies. Of all 9-(3-
a
3-chlorobenzyl and
b-carboline nucleus,
O
O
DMF/NaH
N
N
N
SeO2
R9Br
N
R9
N
N
R9
CHO
CH3
H
CH3
2a R9=n-C4H9
1a R9=n-C4H9
2b R9=i-C4H9
1b R9=i-C4H9
2c R9=CH2C6H5
2d R9=CH2C6H4(4-F)
2e R9=CH2C6H4(3-Cl)
2f R9=(CH2)3C6H5
1c R9=CH2C6H5
1d R9=CH2C6H4(4-F)
1e R9=CH2C6H4(3-Cl)
1f R9=(CH2)3C6H5
1)
2)
CH3OH/CH2Cl2 (2:1 V:V)
H2N
N
n
NaBH3CN/CH3OH
4N HCl/CH3CH2OH
m
3)
.4HCl
N
n
n
H
N
N
m
N
R9
6a R9=CH2C6H4(4-F) m=0 n=1
6b R9=CH2C6H4(4-F) m=1 n=0
6c R9=CH2C6H4(4-F) m=1 n=1
6d R9=CH2C6H4(4-F) m=2 n=1
7a R9=CH2C6H4(3-Cl) m=0 n=1
7b R9=CH2C6H4(3-Cl) m=1 n=0
7c R9=CH2C6H4(3-Cl) m=1 n=1
7d R9=CH2C6H4(3-Cl) m=2 n=1
8a R9=(CH2)3C6H5 m=0 n=1
8b R9=(CH2)3C6H5 m=1 n=0
8c R9=(CH2)3C6H5 m=1 n=1
8d R9=(CH2)3C6H5 m=2 n=1
3a R9=n-C4H9 m=0 n=1
3b R9=n-C4H9 m=1 n=0
3c R9=n-C4H9 m=1 n=1
3d R9=n-C4H9 m=2 n=1
4a R9=i-C4H9 m=0 n=1
4b R9=i-C4H9 m=1 n=0
4c R9=i-C4H9 m=1 n=1
4d R9=i-C4H9 m=2 n=1
5a R9=CH2C6H5 m=0 n=1
5b R9=CH2C6H5 m=1 n=0
5c R9=CH2C6H5 m=1 n=1
5d R9=CH2C6H5 m=2 n=1
Scheme 1. Synthesis of b-carbolines 3aed, 4aed, 5aed, 6aed, 7aed and 8aed.

Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
5129
Table 1
Cytotoxicity of
a
b
-carboline derivatives in vitroc (IC50
,
m
M).
.4HCl
N
n
H
N
N
m
n
N
R9
Compd
R9
m
n
769-Pb
KB
BGC-823
786e0
HepG2
A375
HT-29
OS-RC-2
22RV1
MCF-7
3a
3b
3c
3d
4a
4b
4c
4d
5a
5b
5c
5d
6a
6b
6c
6d
7a
7b
7c
7d
8a
8b
8c
8d
n-C4H9
n-C4H9
n-C4H9
n-C4H9
i-C4H9
i-C4H9
i-C4H9
i-C4H9
CH2C6H5
CH2C6H5
CH2C6H5
CH2C6H5
CH2C6H4(p-F)
CH2C6H4(p-F)
CH2C6H4(p-F)
CH2C6H4(p-F)
CH2C6H4(m-Cl)
CH2C6H4(m-Cl)
CH2C6H4(m-Cl)
CH2C6H4(m-Cl)
(CH2)3C6H5
(CH2)3C6H5
(CH2)3C6H5
(CH2)3C6H5
0
1
1
2
0
1
1
2
0
1
1
2
0
1
1
2
0
1
1
2
0
1
1
2
1
0
1
1
1
0
1
1
1
0
1
1
1
0
1
1
1
0
1
1
1
0
1
1
43.7
75.6
14.9
69.2
25.4
>100
>100
>100
34.9
15.1
19.2
71.7
23.9
11.7
19.6
13.3
26.7
24.5
11.4
28.5
14.8
1.7
>100
53.3
>100
41.0
40.0
32.6
99.2
44.7
72.8
56.2
>100
41.0
66.9
33.8
>100
28.8
34.6
29.7
38.9
12.0
10.8
9.3
>100
22.4
56.7
19.9
28.7
20.2
33.5
18.6
68.6
39.3
39.6
16.7
65.5
30.1
36.3
17.7
28.1
7.5
9.3
8.8
18.2
4.4
5.0
10.0
4.9
<0.08
>100
26.2
27.1
20.4
>100
28.3
53.8
27.2
59.5
23.5
22.0
27.0
61.1
20.0
22.8
20.7
16.4
9.3
18.0
7.2
10.6
4.6
3.5
8.5
16.0
<0.08
<1.3
31.3
52.9
54.4
56.9
84.6
82.9
68.3
75.8
28.0
26.9
25.8
56.2
25.2
28.6
34.5
51.8
14.6
13.1
11.9
14.6
14.7
18.1
11.6
4.7
>100
10.1
41.4
9.3
31.9
31.3
26.4
14.8
50.9
21.3
47.0
26.3
32.5
12.5
22.5
20.4
34.6
10.9
18.1
12.6
29.8
10.2
10.1
9.9
112
17.2
40.3
12.6
16.5
17.9
23.0
19.3
73.2
24.5
34.3
12.8
65.9
29.9
32.9
19.1
28.6
6.1
5.7
5.9
21.9
5.3
6.9
10.2
4.6
0.08
<1.3
59.6
66.2
75.8
55.6
96.0
72.2
61.7
64.4
73.0
62.6
92.8
74.6
8.4
12.1
17.0
19.5
63.8
32.7
33.4
12.3
58.8
27.8
29.5
18.8
27.0
6.1
5.7
5.6
16.3
3.9
3.7
3.7
85.7
0.38
4.2
>100
83.1
62.3
53.6
51.6
58.2
58.8
44.2
53.1
52.0
17.2
14.7
17.6
20.8
25.7
17.7
16.6
27.4
12.4
1.3
>100
44.2
60.0
39.9
>100
32.5
32.9
30.0
57.9
14.0
12.4
10.3
9.2
3.2
3.1
9.7
4.6
14.7
5.9
7.5
20.7
13.4
1.5
8.1
11.1
10.0
51.1
3.4
<0.08
<1.3
2.4
12.4
19.2
7.1
Cisplatin
Paclitaxel
Adriamycin
9.4
0.81
17.2
0.08
0.6
11.5
<1.3
3.1
5.1
a
Cytotoxicity as IC50 for each cell line is the concentration of compound, which reduced by 50% the optical density of treated cells with respect to untreated using the MTT
assay.
b
Cell lines include renal carcinoma (769-P, 786-0 and OS-RC-2), epidermoid carcinoma of the nasopharynx (KB), gastric carcinoma (BGC-823), liver carcinoma (HepG2),
melanoma (A375), colon carcinoma (HT-29), prostate carcinoma (22RV1) and breast carcinoma (MCF-7).
c
The data represent the mean values of three independent determinations.
chloro)benzyl and 9-(3-phenyl)propyl substituted
derivatives, compounds 7b, 7c, 8b and 8c, having
diethylamino propylamino moiety in position-1, were found to be
the most potent cytotoxic agents with IC50 value of lower than
b
-carboline
N,N-
from melting curves (not shown) and the results of Tm analysis
performed with CT-DNAwere shown in Fig. 2. CT-DNAwhich melt at
a low temperature (53.2 ꢀC in PE buffer) afforded a sensitive deter-
mination of the DNA binding capacity of the studied molecules. As
indicated in Fig. 2, compound 3c, bearing a N,N-diethylamino pro-
pylamino group and n-butyl subsituent in position-1 and 9,
respectively, markedly stabilized CT-DNA against heat denaturation
a
20
indicated that (1) the 3-chlorobenzyl and 3-phenylpropyl substit-
uents in position-9 of -carboline nucleus were the suitable phar-
mM against 10 human tumor cell lines investigated. These results
b
macophoric group giving rise to potent antitumor agents; (2) the
length of the alkylamino side chain moiety also affected their
cytotoxic potencies, and three CH2 units were more favorable.
with
D
Tm value (
D
Tm ¼ TmdrugeDNA complex ꢁ TDmNA alone) of 19.2 ꢀC.
Whereas, 9-isobutyl (compound 4c) and 9-benzyl (compound 5c)
substituted
DNA thermal stability with
b
-carboline congeners exhibited weaker effects on CT-
D
Tm value of 16.1 and 14.8 ꢀC, respec-
tively. Unexpectedly, replacement of the n-butyl substituent in
position-9 of compound 3c with 4-fluorobenzyl group afforded
compound 6c, which displayed the poorest DNA binding capacity
3.2. UV spectral absorbance
The interaction of the selected compounds 3e8c with calf
thymus DNA (CT-DNA) was examined by UV spectroscopy. Fig. 1
illustrates the absorption spectra of compounds 3e8c in the PE
buffer (1 mM Na2HPO4, 0.1 mM EDTA, pH 7.4) in the presence of
increasing amounts of CT-DNA. In all cases, the binding of the drugs
to CT-DNA results in considerable spectral changes, characterized
by a slight bathochromic shift and a marked hypochromism. These
results suggested that these compounds had a significant interac-
tion with CT-DNA double helix.
with
6
Tm value of 8.1 ꢀC. Interestingly, compounds 7c and 8c,
bearing 3-chlorobenzyl and 3-phenylpropyl group in position-9,
respectively, were found to be the most potent compounds with
6
Tm value of 19.9 and 21.5 ꢀC, respectively. The results suggested
that (1) such compounds could significantly stabilize the double
helixof CT-DNA; (2) the introduction of appropriate substituent into
position-9 of b-carboline nucleus played a vital role in determining
their DNA binding potency, and 3-chlorobenzyl and 3-phenylpropyl
group were more favorable.
3.3. DNA thermal denaturation studies
3.4. Fluorescence studies
Melting temperature (Tm) measurements were deployed to
evaluate relative affinity for DNA of compounds 3e8c. The Tm of CT-
DNA in the presence and absence of compounds 3e8c were obtained
b
-Carboline alkaloids present intrinsic fluorescence properties
which could be used to evaluate their DNA binding potencies. The

5130
Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
effect of CT-DNA on the fluoresence intensity of the selected
-carbolines 3e8c was determined by the use of fluoresence
decreased with the increasing concentrations of added CT-DNA.
When the concentration of added CT-DNA was increased to
b
spectroscopy. From the titration of compounds 3e8c (Fig. 3), the
fluorescence intensity of all investigated compounds gradually
90 mM, the fluorescence intensity of all investigated compounds
was lowered to their minimum. In addition, over the course of the
0.6
0.6
0.5
0.4
0.3
0.2
0.1
0.0
3c
6c
0 uM
0.5
30 uM
0 uM
30 uM
60 uM
90 uM
120 uM
150 uM
180 uM
210 uM
0.4
0.3
0.2
0.1
0.0
60 uM
90 uM
120 uM
150 uM
180 uM
250
300
350
400
250
300
350
400
Wavelength (nm)
Wavelength (nm)
0.6
0.6
0.4
0.2
0.0
7c
0 uM
0 uM
4c
30 uM
60 uM
90 uM
120 uM
150 uM
180 uM
210 uM
30 uM
60 uM
90 uM
120 uM
150 uM
180 uM
210 uM
0.5
0.4
0.3
0.2
0.1
0.0
250
300
350
400
250
300
350
400
Wavelength (nm)
Wavelength (nm)
0.7
0.7
5c
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0 uM
8c
0 uM
30 uM
60 uM
90 uM
120 uM
150 uM
180 uM
210 uM
30 uM
60 uM
90 uM
120 uM
150 uM
180 uM
210 uM
250
300
350
400
250
300
350
400
Wavelength (nm)
Wavelength (nm)
Fig. 1. Absorption spectra for compounds 3e8c in 1 ml PE buffer (1 mM Na2HPO4, 0.1 mM EDTA, pH 7.4) at different molarities of CT-DNA: top curve (0.0) and bottom curve
(210 M) were recorded in quartz cells (10 mm path length) by a UVevisible spectrophotometer at room temperature.
m

Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
5131
silica gel (Kieselgel 60 F254, Merck). 9-n-Butyl-1-methyl-
line (1a) [26], 9-benzyl-1-methyl-
phenyl)propyl-1-methyl- -carboline (1f) [26] are known
b-carbo-
b-carboline (1c) [26] and 9-(3-
b
compounds. NMR spectra were recorded on a Varian Mercury-Plus
300 spectrometer, Bruker AVANCE 400 and Varian INOVA500NB in
D2O or DMSO-d6 or D2O þ DMSO-d6 at 25 ꢀC. All chemical shifts (
d)
are quoted in parts per million downfield from TMS and coupling
constants (J) are given in Hertz. Mass spectra were obtained from
VG ZAB-HS and LCMS-2010A. High-resolution mass spectrometry
(HRMS); was performed on MAT95XP. Infrared (IR) spectra were
measured on VECTOR 22 spectrometer using a potassium bromide
(KBr) disk, scanning from 400 to 4000 cmꢁ1
.
5.2. General procedures for the synthesis of 9-alkyl substituted
b-carbolines 1b, 1d and 1e
A mixture of 1-methyl-b-carboline (1.82 g, 10 mmol) and
Fig. 2. Variation of the
6Tm of the complexes between the tested compounds and CT-
anhydrous DMF (50 ml) was stirred at room temperature until
clear, and then 60% NaH (0.6 g, 15 mmol) and halogenated alkane
(15 mmol) were added. The mixture was stirred at room temper-
ature. After completion of the reaction as indicated by TLC, the
solution was poured into H2O (50 ml) and extracted with ethyl
acetate. The organic phase was washed with water and brine, then
dried over anhydrous sodium sulfate, filtered and evaporated. The
resulting oil was purified by silica column chromatography with
ethyl acetate as the eluent. Upon recrystallization, white solid were
obtained.
DNA. Melting temperature measurements were performed in PE buffer (1 mM
Na2HPO4, 0.1 mM EDTA) at pH 7.4 with a drug/DNA ration of 0.2. Adr is abbreviation of
adriamycin (Doxorubicin Hydrochloride).
fluorescence quenching of all investigated compounds, a slight
bathochromic shift was also observed. These results suggested that
such b-carbolines could effectively interact with DNA.
4. Conclusion
With the aim of elucidating the structureeactivity relationship
studies and probing the structural requirement for the potent
5.2.1. 9-Isobutyl-1-methyl-
b-carboline (1b)
Yield 65%; 1H NMR (300 MHz, CDCl3):
d
8.30 (d, J ¼ 5.1 Hz,1H, H-
antitumor activity of
b-carbolines, a series of novel 1-(N,N-dia-
3), 8.08 (d, J ¼ 7.8 Hz,1H, H-4), 7.82 (d, J ¼ 5.1 Hz,1H, H-8), 7.22e7.57
(m, 3H, H-5, H-6, H-7), 4.33 (d, J ¼ 7.5 Hz, 2H, NCH2CH(CH3)2), 3.03 (s,
3H, CH3), 2.22e2.31(m, 1H, NCH2CH(CH3)2), 0.94 (s, 3H, CH(CH3)2),
lkylaminoalkylamino)- and 9-alkyl substituted
b
-carbolines has
been synthesized and evaluated as potent cytotoxic and DNA
intercalating agents. Their cytotoxic potencies and DNA inter-
calating capacities evidenced the importance of the length of N,N-
dialkylaminoalkylamino group in position-1 and the nature of alkyl
0.92 (s, 3H, CH(CH3)2).13C NMR (75 MHz, CDCl3):
d 142.0,141.4,138.1,
135.4, 129.1, 127.9, 121.4, 121.2, 119.6, 113.0, 110.6, 51.9, 30.9, 24.2(d),
20.5; FAB-MS m/z (M þ 1) 239.
substituent in position-9 of
b-carboline nucleus. The
3-chlorobenzyl and 3-phenylpropy substituents in position-9 were
the suitable pharmacophore giving rise to potent antitumor agents
and the optimal length of the alkylamino side chain moiety were
three CH2 units.
5.2.2. 9-(4-Fluorobenzyl)-1-methyl-
b
-carboline (1d)
Yield 72%; 1H NMR (300 MHz, CDCl3):
d
8.33 (d, J ¼ 5.1 Hz, 1H, H-
3), 8.13 (d, J ¼ 7.8 Hz,1H, H-4), 7.86 (d, J ¼ 5.1 Hz,1H, H-8), 7.50e7.55
(m, 1H, H-7), 7.25e7.34 (m, 2H, H-5, H-6), 6.96 (d, 4H, J ¼ 7.2 Hz, Ph-
H), 5.75 (s, 2H, NCH2-4-fluorophenyl), 2.87 (s, 3H, CH3). 13C NMR
An overview of the cytotoxic activities data of all new synthe-
sized
position-1 and of the earlier reported
ible alkylamino side chain at position-3 [31,32] clearly indicated
that (i) the N9-arylated alkyl substituted
-carbolines represented
b
-carbolines bearing a flexible alkylamino side chain at
(75 MHz, CDCl3):
d 163.8, 160.5, 141.8, 141.6, 138.7, 135.5, 133.8,
b
-carbolines bearing a flex-
129.2, 128.6, 127.2, 127.1, 121.7, 121.5, 120.3, 116.2, 115.9, 113.1, 109.8,
47.7, 23.5(d); FAB-MS m/z (M þ 1) 305.
b
the most interesting cytotoxic activities; (ii) the optimal length of
the alkylamino side chain moiety were three CH2 units and (iii)
5.2.3. 9-(3-Chlorobenzyl)-1-methyl-
b
-carboline (1e)
8.34 (d, J ¼ 5.1 Hz, 1H, H-
Yield 76%; 1H NMR (300 MHz, CDCl3):
d
their cytotoxic potencies had no difference between
bearing a flexible alkylamino side chain at C-1 and C-3.
An attempt to include all of the 1,9-disubstituted
into a correlation of cytotoxic potency with
b
-carbolines
3), 8.14e8.16 (m,1H, H-4), 7.86 (d, J ¼ 5.1 Hz,1H, H-8), 7.50e7.56 (m,
1H, H-7), 7.15e7.32 (m, 3H, H-5, H-6, Ph-H), 7.03 (s, 1H, Ph-H), 6.81
(d, J ¼ 7.2 Hz, 2H, Ph-H), 5.74 (s, 2H, CH2), 2.87 (s, 3H, CH3). 13C NMR
b
-carbolines
6
Tm values was
(75 MHz, CDCl3):
d 141.8, 141.5, 140.3, 138.8, 135.5, 135.1, 130.5,
unsuccessful, but this result has been observed for other DNA
binding agents. Because the DNA binding process is complicated
and dependent on many structural factors, undoubtedly, a more
detailed molecular mechanics study on the DNA binding of these
compounds is needed.
129.3, 128.7, 128.0, 125.8, 123.7, 121.7, 121.6, 120.4, 113.2, 109.8, 47.9,
23.5(d); FAB-MS m/z (M þ 1) 321.
5.3. General procedures for the synthesis of 9-alkyl substituted
b-carboline-1-carboxaldehydes 2aef
5. Experimental protocols
To a solution of 1aef (5 mmol) in dioxane (100 ml) was added
5.1. Reagents and general procedures
SeO2 (10 mmol). The suspension was refluxed for 2 h. After
completion of the reaction as indicated by TLC, the mixture was
cooled and filtered through Celite. The filtrate was evaporated
under reduced pressure. The residue was crystallized from acetone
or acetoneepetroleum ether to afford white solid.
All solvents were of reagent grade and, when necessary, were
purified and dried by standard methods. Reactions and products
were routinely monitored by thin-layer chromatography (TLC) on

5132
Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
700
600
500
400
300
200
100
0
3c
300
6c
250
0 uM
15uM
30uM
45uM
60uM
75uM
90uM
0 uM
200
15 uM
30 uM
45 uM
60 uM
75 uM
90 uM
150
100
50
0
400
450
500
/ nm
550
400
450
500
/ nm
550
700
600
500
400
300
200
100
0
600
4c
500
400
300
200
100
0
7c
0 uM
15uM
30uM
45uM
60uM
75uM
90uM
0 uM
15 uM
30 uM
45 uM
60 uM
75 uM
90 uM
400
450
500
/ nm
550
400
450
500
/ nm
550
800
500
400
300
200
100
0
5c
700
600
500
400
300
200
100
0
8c
0 uM
15 uM
30 uM
45 uM
60 uM
75 uM
90 uM
0 uM
15 uM
30 uM
45 uM
60 uM
75 uM
90 uM
400
450
500
/ nm
550
400
450
500
/ nm
550
Fig. 3. Fluorescence spectra of the various
b-carbolines upon incubation with graded concentration of CT-DNA. A fixed concentration of the various
b-carbolines (10 mM) was
incubated with increasing concentration of CT-DNA from 0 to 90
m
M in PE buffer (1 mM Na2HPO4, 0.1 mM EDTA, pH 7.4).

Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
5133
5.3.1. 9-n-Butyl-
b
-carboline-1-carboxaldehyde (2a)
10.31 (s, 1H, CHO); 8.63
(50 mL) and washed with aqueous Na2CO3 (pH 10, 50 mL). The
organic layer was separated, dried over anhydrous Na2SO4, filtered,
and concentrated under vacuum. The residue was purified by flash
chromatography on silica gel (CH2Cl2/CH3OH/NH4OH, 95:5:1) to
gain yellow oil. The oil was dissolved in 4N HCl/ethanol (20 mL) and
stirred at room temperature for 30 min, then removed the solvent
under reduced pressure to obtain yellow solid. The solid were dried
in vacuo at 100 ꢀC for 3 days to remove the residual ethanol.
Yield 65%; 1H NMR (300 MHz, CDCl3):
d
(d, J ¼ 4.8 Hz, 1H, H-3); 8.13e8.17 (m, 2H, H-4, H-8); 7.62e7.68 (m,
1H, H-7); 7.53 (d, J ¼ 8.4 Hz, 1H, H-5); 7.24e7.32 (m, 1H, H-6); 4.86
(t,
J
¼
7.5 Hz, 2H, NCH2CH2CH2CH3); 1.70e1.80 (m, 2H,
NCH2CH2CH2CH3); 1.26e1.41 (m, 2H, NCH2CH2CH2CH3); 0.93 (t,
J ¼ 7.2 Hz, 3H, NCH2CH2CH2CH3). 13C NMR (75 MHz, CDCl3):
d 193.9,
142.5, 138.3, 137.7, 135.1, 132.5, 129.3, 121.4, 120.9, 120.8, 118.6, 110.7,
46.8, 32.1, 20.3, 14.2; FAB-MS m/z (M þ 1) 253.
5.4.1. 1-[N-(2-diethylamino)-ethyl]-methylamino-9-n-butyl-b-
5.3.2. 9-Isobutyl-
b
-carboline-1-carboxaldehyde (2b)
carboline hydrochloride salt (3a)
Yield 62%; 1H NMR (300 MHz, CDCl3):
d
10.31 (s, 1H, CHO), 8.63
Yield 40%; IR (KBr, cmꢁ1) v: 2947, 2792, 2581, 1623, 1494, 1443,
(d, J ¼ 4.8 Hz, 1H, H-3), 8.14e8.19 (m, 2H, H-4, H-8), 7.31e7.66 (m,
3H, H-5, H-6, H-7), 4.78 (t, J ¼ 7.5 Hz, 2H, NCH2CH(CH3)2), 2.04e2.17
(m, 1H, NCH2CH(CH3)2), 0.83 (s, 3H, CH3), 0.80 (s, 3H, CH3). 13C NMR
(75 MHz, CDCl3):
121.4, 120.8, 118.7, 111.3, 109.9, 53.4, 30.0, 29.4, 20.1; FAB-MS m/z
(M þ 1) 253.
1389, 1292, 1198, 1134, 1026, 758; 1H NMR (300 MHz, DMSO-
d6 þ D2O): 8.41 (d, J ¼ 5.1 Hz, 1H, H-3), 8.30e8.33 (m, 2H, H-4, H-
d
8), 7.78 (d, J ¼ 8.1 Hz, 1H, H-5), 7.64e7.69 (m, 1H, H-7), 7.33 (t,
J ¼ 7.5 Hz, 1H, H-6), 4.99 (s, 2H, CH2NHCH2CH2N), 4.56 (t, J ¼ 7.2 Hz,
2H, NCH2CH2CH2CH3), 3.64e3.66 (m, 4H, NHCH2CH2N), 3.18e3.25
(m, 4H, N(CH2CH3)2), 1.70e1.80 (m, 2H, NCH2CH2CH2CH3),
1.25e1.37 (m, 8H, NCH2CH2CH2CH3, N(CH2CH3)2), 0.89 (t, J ¼ 7.2 Hz,
d 193.9, 142.9, 138.3, 138.0, 135.3, 132.5, 129.2,
5.3.3. 9-Benzyl-
b
-carboline-1-carboxaldehyde (2c)
10.20 (s, 1H, CHO), 8.65
3H, NCH2CH2CH2CH3); 13C NMR (75 MHz, D2O):
d 144.3, 135.1,
Yield 78%; 1H NMR (300 MHz, CDCl3):
d
132.6, 132.4, 130.8, 129.7, 122.5, 121.9, 118.6, 116.9, 110.9, 49.2, 48.3,
(d, J ¼ 5.1 Hz, 1H, H-3), 8.18e8.23 (m, 2H, H-4, H-8), 7.34e7.63 (m,
46.7, 45.4, 43.5, 32.2, 19.8, 13.5, 8.6; ESI-MS m/z: 353.4 (M þ 1)þ.
3H, H-5, H-6, H-7), 7.16e7.19 (m, 3H, Ph-H), 6.92e6.95 (m, 2H, Ph-
H), 6.18 (s, 2H, NCH2). 13C NMR (75 MHz, CDCl3):
d
193.9, 143.0,
5.4.2. 1-[N-(3-dimethylamino)-propyl]-methylamino-9-n-butyl-b-
138.9, 138.1, 137.7, 135.8, 132.8, 129.7, 128.8, 127.4, 126.3, 121.6, 121.3,
121.1, 118.8, 111.2, 50.4; FAB-MS m/z (M þ 1) 287.
carboline hydro-chloride salt (3b)
Yield 48%; IR (KBr, cmꢁ1) v: 3013, 2956, 2869, 2611, 1625, 1524,
1462, 1382, 1338, 1243, 1170, 1058, 774, 752; 1H NMR (300 MHz,
5.3.4. 9-(4-Fluorobenzyl)-
b
-carboline-1-carboxaldehyde (2d)
DMSO-d6 þ D2O): 8.49 (d, J ¼ 5.4 Hz, 1H, H-3), 8.43 (d, J ¼ 5.4 Hz,
d
Yield 72%; 1H NMR (300 MHz, CDCl3):
d
10.20 (s, 1H, CHO), 8.66
1H, H-4), 8.37 (d, J ¼ 8.1 Hz, 1H, H-8), 7.82 (d, J ¼ 8.4 Hz, 1H, H-5),
7.70 (t, J ¼ 7.5 Hz, 1H H-7,), 7.36 (t, J ¼ 7.2 Hz, 1H, H-6), 4.95 (s, 2H,
CH2NHCH2CH2CH2N), 4.60 (t, J ¼ 6.6 Hz, 2H, NCH2CH2CH2CH3), 3.32
(t, J ¼ 7.2 Hz, 2H, NHCH2CH2CH2N), 3.22 (t, J ¼ 7.2 Hz, 2H,
NHCH2CH2CH2N), 2.76 (s, 6H, N(CH3)2), 2.18e2.27 (m, 2H,
NHCH2CH2CH2N), 1.69e1.79 (m, 2H, NCH2CH2CH2CH3), 1.31e1.40
(m, 2H, NCH2CH2CH2CH3), 0.89 (t, J ¼ 7.2 Hz, 3H, NCH2CH2CH2CH3);
(d, J ¼ 5.1 Hz, 1H, H-3), 8.17e8.23 (m, 2H, H-4, H-8), 7.35e7.64 (m,
3H, H-5, H-6, H-7), 6.84e6.95 (m, 4H, 4-fluorophenyl-H), 6.14 (s,
2H, NCH2). 13C NMR (75 MHz, CDCl3):
d 194.0, 163.6, 160.4, 142.8,
139.0, 138.0, 135.6, 133.5, 132.8, 129.8, 128.1, 128.0, 121.6, 121.4,
121.2, 118.9, 115.8, 115.5, 111.1, 49.8; FAB-MS m/z (M þ 1) 305.
5.3.5. 9-(3-Chlorobenzyl)-
b
-carboline-1-carboxaldehyde (2e)
10.20 (s, 1H, CHO), 8.67
13C NMR (75 MHz, D2O):
d 144.7, 136.3, 133.4, 132.7, 131.1, 126.1,
Yield 76%; 1H NMR (300 MHz, CDCl3):
d
122.7, 122.0, 118.7, 117.7, 110.9, 54.5, 45.9 (2C), 45.4, 43.3, 31.8, 21.8,
(d, J ¼ 4.8 Hz, 1H, H-3), 8.18e8.23 (m, 2H, H-4, H-8), 7.58e7.64 (m,
1H, H-7), 7.36e7.44 (m, 2H, H-5, H-6), 7.09e7.17 (m, 2H, 3-
chlorophenyl-H), 6.81e6.97 (m, 2H, 3-chlorophenyl-H), 6.16 (s,
19.8, 13.5; ESI-MS m/z: 339.4 (M þ 1)þ.
5.4.3. 1-[N-(3-diethylamino)-propyl]-methylamino-9-n-butyl-b-
2H, NCH2). 13C NMR (75 MHz, CDCl3):
d
194.1, 142.7, 140.0, 139.1,
carboline hydro-chloride salt (3c)
138.0, 135.7, 134.7, 132.8, 130.1, 129.9, 127.7, 126.5, 124.5, 121.6, 121.5,
121.2, 118.9, 111.0, 50.1; FAB-MS m/z (M þ 1) 321.
Yield 46%; IR (KBr, cmꢁ1) v: 2958, 2685, 1624, 1496, 1461, 1383,
1337, 1201, 1135, 1044, 758; 1H NMR (300 MHz, DMSO-d6 þ D2O):
d
8.49 (d, J ¼ 5.1 Hz, 1H, H-3), 8.42 (d, J ¼ 5.4 Hz, 1H, H-4), 8.36 (d,
5.3.6. 9-(3-Phenylpropyl)-
b
-carboline-1-carboxaldehyde (2f)
J ¼ 8.1 Hz, 1H, H-8), 7.81 (d, J ¼ 8.4 Hz, 1H, H-5), 7.70 (t, J ¼ 7.5 Hz,
Yield 68%; 1H NMR (300 MHz, CDCl3):
d
10.30 (s, 1H, CHO), 8.62
1H, H-7), 7.35 (t, 7.2 Hz, 1H, H-6), 4.94 (s, 2H,
J
¼
(d, J ¼ 4.8 Hz, 1H, H-3), 8.12e8.16 (m, 2H, H-4, H-8), 7.58e7.63 (m,
1H, H-7), 7.13e7.37 (m, 7H, H-5, H-6, Ph-H), 4.89 (t, J ¼ 7.8 Hz, 2H,
NCH2CH2CH2Ph), 2.71 (t, J ¼ 7.5 Hz, 2H, NCH2CH2CH2Ph), 2.07e2.18
CH2NHCH2CH2CH2N), 4.59 (t, J ¼ 6.9 Hz, 2H, NCH2CH2CH2CH3), 3.31
(t, J ¼ 6.9 Hz, 2H, NHCH2CH2CH2N), 3.20 (t, J ¼ 7.5 Hz, 2H,
NHCH2CH2CH2N), 3.08e3.15 (m, 4H, N(CH2CH3)2), 2.16e2.26 (m,
2H, NHCH2CH2CH2N), 1.69e1.79 (m, 2H, NCH2CH2CH2CH3),
1.30e1.37 (m, 2H, NCH2CH2CH2CH3), 1.23 (t, J ¼ 7.2 Hz, 6H,
N(CH2CH3)2), 0.88 (t, J ¼ 7.2 Hz, 3H, NCH2CH2CH2CH3); 13C NMR
(m, 2H, NCH2CH2CH2Ph). 13C NMR (75 MHz, CDCl3):
d 194.0, 142.3,
141.3, 138.4, 137.7, 135.1, 132.5, 129.4, 128.6, 128.5(2C), 126.2, 121.5,
120.9, 118.7, 110.6, 46.5, 33.1, 31.5; FAB-MS m/z (M þ 1) 315.
(75 MHz, DMSO-d6 þ D2O):
d 144.2, 133.9, 133.9, 133.2, 131.9, 131.5,
5.4. General procedures for the synthesis of
4aed, 5aed, 6aed, 7aed and 8aed
b
-carbolines 3aed,
123.6, 122.0, 120.0, 117.6, 111.8, 48.6, 47.1, 46.4, 45.6 (2C), 32.6, 21.0,
20.3, 14.6, 9.3; ESI-MS m/z: 367.4 (M þ 1)þ.
A mixture of
b
-carboline-1-carboxaldehydes (1 mmol), diamine
5.4.4. 1-[N-(4-diethylamino)-butyl]-methylamino-9-n-butyl-b-
(1.2 mmol), anhydrous methanol (6 mL) and anhydrous CH2Cl2
(3 mL) was stirred at room temperature overnight. The solvent was
evaporated under vacuum to give the crude schiff base, which was
used directly in the next step without further purification.
NaBH3CN (10 mmol) was added to a solution of the above-
mentioned crude schiff base in anhydrous CH3OH (10 mL) at 0 ꢀC.
The mixture was stirred at room temperature for 24 h and then
concentrated under vacuum. The residue was dissolved in CH2Cl2
carboline hydro-chloride salt (3d)
Yield 50%; IR (KBr, cmꢁ1) v: 2958, 2693, 1625, 1545, 1496, 1462,
1337, 1296, 1201, 1136, 1040, 759; 1H NMR (300 MHz, DMSO-
d6 þ D2O): 8.63 (d, J ¼ 5.4 Hz,1H, H-3), 8.57 (d, J ¼ 5.4 Hz,1H, H-4),
d
8.39 (d, J ¼ 8.1 Hz, 1H, H-8), 7.91 (t, J ¼ 7.5 Hz, 1H, H-7), 7.84 (d,
J ¼ 8.4 Hz, 1H, H-5), 7.53 (t, J ¼ 7.2 Hz, 1H, H-6), 5.09 (s, 2H,
CH2NHCH2CH2CH2CH2N), 4.62 (t, J ¼ 7.5 Hz, 2H, NCH2CH2CH2CH3),
3.47 (t, J ¼ 7.5 Hz, 2H, NHCH2CH2CH2CH2N), 3.23e3.31 (m, 6H,

5134
Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
NHCH2CH2CH2CH2N), 1.91e1.97 (m, 4H, NHCH2CH2CH2CH2N),
1.81e1.87 (m, 2H, NCH2CH2CH2CH3), 1.38e1.42 (m, 2H,
NCH2CH2CH2CH3), 1.34 (t, J ¼ 7.5 Hz, 6H, N(CH2CH3)2), 0.94 (t,
134.0, 132.4, 132.1, 127.4, 122.9, 122.2, 119.2, 117.7, 111.9, 52.2, 51.2,
48.3, 47.8, 46.5, 30.1, 23.4, 21.2,19.5, 8.7; ESI-MS m/z: 381.4 (M þ 1)þ.
J ¼ 7.5 Hz, 3H, NCH2CH2CH2CH3); 13C NMR (75 MHz, D2O):
d
144.9,
5.4.9. 1-[N-(2-diethylamino)-ethyl]-methylamino-9-benzyl-b-
136.4, 133.6, 132.8, 131.3, 126.4, 122.9, 122.2, 118.9, 117.8, 111.1, 51.2,
48.4, 47.7, 45.9, 45.5, 31.8, 23.3, 21.1, 19.9, 13.5, 8.7; ESI-MS m/z:
381.4 (M þ 1)þ.
carboline hydro-chloride salt (5a)
Yield 45%; IR (KBr, cmꢁ1) v: 2977, 2660, 1624, 1495, 1460, 1389,
1336, 1297, 1134, 1025, 753; 1H NMR (300 MHz, DMSO-d6 þ D2O):
d
8.46 (d, J ¼ 5.1 Hz, 1H, H-3), 8.39 (br s, 1H, H-4), 8.37 (br s, 1H, H-8),
5.4.5. 1-[N-(2-diethylamino)-ethyl]-methylamino-9-isobutyl-
b-
7.72 (d, J ¼ 8.4 Hz, 1H, H-5), 7.63 (t, J ¼ 7.2 Hz, 1H, H-7), 7.35 (t,
J¼ 7.2Hz,1H, H-6), 7.22e7.29(m, 3H, Ph-H), 6.96e6.99 (m, 2H, Ph-H),
5.93 (s, 2H, NCH2-Ph), 4.79 (s, 2H, CH2NHCH2CH2N), 3.45e3.49 (m,
4H, NHCH2CH2N), 3.12e3.19 (m, 4H, N(CH2CH3)2), 1.23 (t, J ¼ 7.2 Hz,
carboline hydro-chloride salt (4a)
Yield 55%; CH2Cl2/CH3OH, 95:5; 2963, 2672, 1623, 1497, 1464,
1384, 1335, 1135, 1042, 777; 1H NMR (300 MHz, DMSO-d6 þ D2O):
d
8.45 (d, J ¼ 5.4 Hz, 1H, H-3), 8.32e8.36 (m, 2H, H-4, H-8), 7.83 (d,
6H, CH3); 13C NMR (75 MHz, DMSO-d6 þ D2O):
d 143.6, 138.1, 135.6,
J ¼ 8.7 Hz, 1H, H-5), 7.63e7.69 (m, 1H, H-7), 7.33 (t, J ¼ 7.8 Hz,1H, H-
134.2, 133.3, 132.4, 131.1, 129.7, 128.3, 126.3, 123.2, 121.9, 120.6, 117.0,
6), 4.96 (s, 2H, CH2NHCH2CH2N), 4.42 (d, 7.5 Hz, 2H,
J
¼
111.7, 48.7, 47.8, 47.5, 46.9, 42.1, 9.4; ESI-MS m/z: 387.4 (M þ 1)þ.
NCH2CH(CH3)2), 3.66e3.68 (m, 4H, NHCH2CH2N), 3.18e3.25 (m, 4H,
N(CH2CH3)2), 2.11e2.20 (m, 1H, NCH2CH(CH3)2), 1.28 (t, J ¼ 7.2 Hz,
6H, N(CH2CH3)2), 0.86 (d, J ¼ 6.6 Hz, 6H, NCH2CH(CH3)2); 13C NMR
5.4.10. 1-[N-(3-dimethylamino)-propyl]-methylamino-9-benzyl-b-
carboline hydro-chloride salt (5b)
(75 MHz, D2O,):
d
145.0,135.8,133.1,132.4, 130.0, 129.4,122.6, 122.0,
Yield 65%; IR (KBr, cmꢁ1) v: 2976, 2661, 1624, 1494, 1458, 1336,
1297, 1199, 1134, 1027, 749; 1H NMR (300 MHz, DMSO-d6 þ D2O):
118.6, 117.3, 111.6, 52.0, 48.5, 48.3, 46.6, 43.3, 30.1, 19.4, 8.6; ESI-MS
m/z: 353.4 (M þ 1)þ.
d
8.46 (d, J ¼ 5.4 Hz, 1H, H-3), 8.36e8.39 (m, 2H, H-4, H-8), 7.75 (d,
J ¼ 8.4 Hz, 1H, H-5), 7.61e7.67 (m, 1H, H-7), 7.36 (t, J ¼ 7.5 Hz, 1H, H-
6), 7.20e7.31 (m, 3H, Ph-H), 6.94e6.97 (m, 2H, Ph-H), 5.92 (s, 2H,
NCH2-Ph), 4.69 (s, 2H, CH2NHCH2CH2CH2N), 3.05e3.15 (m, 4H,
NHCH2CH2CH2N), 2.79 (s, 6H, CH3), 2.02e2.12 (m, 2H,
5.4.6. 1-[N-(3-dimethylamino)-propyl]-methylamino-9-isobutyl-b-
carboline hydro-chloride salt (4b)
Yield 36%; IR (KBr, cmꢁ1) v: 3049, 2957, 2673, 2485, 1623, 1459,
1338, 1289, 1207, 1139, 1045, 749; 1H NMR (300 MHz, DMSO-
NHCH2CH2CH2N); 13C NMR (75 MHz, D2O):
d 144.8, 136.3, 135.5,
d6 þ D2O):
d
8.50 (d, J ¼ 5.4 Hz,1H, H-3), 8.42 (d, J ¼ 5.4 Hz,1H, H-4),
134.0, 132.7, 132.5, 129.6, 128.5, 127.1, 125.6, 123.1, 122.5, 119.1, 117.9,
8.37 (d, J ¼ 7.8 Hz, 1H, H-8), 7.86 (d, J ¼ 8.7 Hz, 1H, H-5), 7.69 (t,
J ¼ 7.5 Hz, 1H, H-7), 7.35 (t, J ¼ 7.2 Hz, 1H, H-6), 4.91 (s, 2H,
CH2NHCH2CH2CH2N), 4.44 (d, J ¼ 7.2 Hz, 2H, NCH2CH(CH3)2), 3.32
(t, J ¼ 7.2 Hz, 2H, NHCH2CH2CH2N), 3.23 (t, J ¼ 7.5 Hz, 2H,
NHCH2CH2CH2N), 2.77 (s, 6H, N(CH3)2), 2.20e2.28 (m, 2H,
NHCH2CH2CH2N), 2.11e2.18 (m, 1H, NCH2CH(CH3)2), 0.87 (d,
110.4, 54.3, 48.4, 45.6 (2C), 43.3, 21.5; ESI-MS m/z: 373.4 (M þ 1)þ.
5.4.11. 1-[N-(3-diethylamino)-propyl]-methylamino-9-benzyl-b-
carboline hydro-chloride salt (5c)
Yield 42%; IR (KBr, cmꢁ1) v: 2977, 2661, 1624, 1495, 1459, 1336,
1297, 1199, 1134, 1026, 751; 1H NMR (300 MHz, DMSO-d6 þ D2O):
J ¼ 6.6 Hz, 6H, NCH2CH(CH3)2); 13C NMR (75 MHz, D2O):
d
145.3,
d
8.45 (d, J ¼ 5.1 Hz, 1H, H-3), 8.35 (m, 2H, H-4, H-8), 7.73 (d,
136.3, 133.8, 132.5, 131.6, 126.7, 122.9, 122.1, 118.9, 117.8, 111.8, 54.5,
J ¼ 8.4 Hz,1H, H-5), 7.63 (t, J ¼ 7.5 Hz,1H, H-7), 7.35 (t, J ¼ 7.5 Hz,1H,
H-6), 7.22e7.30 (m, 3H, Ph-H), 6.93e6.95 (m, 2H, Ph-H), 5.91 (s, 2H,
NCH2-Ph), 4.68 (s, 2H, CH2NHCH2CH2CH2N), 3.04e3.13 (m, 8H,
NHCH2CH2CH2N(CH2CH3)2), 2.00e2.10 (m, 2H, NHCH2CH2CH2N),
52.1, 46.3, 45.9, 43.3, 30.0, 21.8, 19.6; ESI-MS m/z: 339.4 (M þ 1)þ.
5.4.7. 1-[N-(3-diethylamino)-propyl]-methylamino-9-isobutyl-b-
carboline hydro-chloride salt (4c)
1.20 (t, J ¼ 7.5 Hz, 6H, CH3); 13C NMR (75 MHz, D2O):
d 144.0, 136.2,
Yield 39%; IR (KBr, cmꢁ1) v: 2926, 2685, 1624, 1495, 1463, 1385,
1335, 1289, 1137, 1044, 758; 1H NMR (300 MHz, DMSO-d6 þ D2O):
134.6, 134.1, 133.9, 131.8, 129.6, 129.1, 128.4, 125.65, 122.7, 122.0,
119.5, 117.1, 110.3, 48.6, 48.2, 47.9, 46.6, 45.4, 21.0, 8.7; ESI-MS m/z:
401.4 (M þ 1)þ.
d
8.49 (d, J ¼ 5.4 Hz, 1H, H-3), 8.42 (d, J ¼ 5.4 Hz, 1H, H-4), 8.36 (d,
J ¼ 7.5 Hz,1H, H-8), 7.85 (d, J ¼ 8.4 Hz,1H, H-5), 7.65e7.71 (m,1H, H-
7), 7.34 (t, J ¼ 7.2 Hz,1H, H-6), 4.90 (s, 2H, CH2NHCH2CH2CH2N), 4.43
(d, J ¼ 7.5 Hz, 2H, NCH2CH(CH3)2), 3.31 (t, J ¼ 7.2 Hz, 2H,
NHCH2CH2CH2N), 3.20 (t, J ¼ 7.5 Hz, 2H, NHCH2CH2CH2N), 3.07e3.15
(m, 4H, N(CH2CH3)2), 2.19e2.27 (m, 2H, NHCH2CH2CH2N), 2.10e2.17
(m, 1H, NCH2CH(CH3)2), 1.24 (t, J ¼ 7.2 Hz, 6H, N(CH2CH3)2), 0.86 (d,
J ¼ 6.3 Hz, 6H, NCH2CH(CH3)2); 13C NMR (75 MHz, DMSO-d6 þ D2O):
5.4.12. 1-[N-(4-diethylamino)-butyl]-methylamino-9-benzyl-b-
carboline hydro-chloride salt (5d)
Yield 61%; IR (KBr, cmꢁ1) v: 2941, 2677, 1624, 1459, 1338, 1199,
1038, 746; 1H NMR (C300 MHz, DMSO-d6 þ D2O):
d 8.55e8.60 (m,
2H, H-3, H-4), 8.47 (d, J ¼ 7.8 Hz, 1H, H-8), 7.80 (d, J ¼ 8.4 Hz, 1H, H-
5), 7.70 (t, J ¼ 7.5 Hz, 1H, H-7), 7.40 (t, J ¼ 7.5 Hz, 1H, H-6), 7.23e7.29
(m, 3H, Ph-H), 7.01 (d, J ¼ 6.3 Hz, 2H, Ph-H), 6.01 (s, 2H, NCH2-Ph),
4.73 (s, 2H, CH2NHCH2CH2CH2CH2N), 3.00e3.10 (m, 8H,
NHCH2CH2CH2CH2N(CH2CH3)2), 1.72 (br s, 4H, NHCH2CH2C
H2CH2N), 1.21 (t, J ¼ 7.2 Hz, 6H, CH3); 13C NMR (75 MHz, DMSO-
d
144.5,134.1,133.9,133.5,132.1,131.4,123.4,121.8,120.0,117.3,112.4,
52.1, 48.6, 47.1, 46.7, 45.6, 30.7, 21.0, 20.5, 9.3; ESI-MS m/z: 367.4
(M þ 1)þ.
5.4.8. 1-[N-(4-diethylamino)-butyl]-methylamino-9-isobutyl-
b-
d6 þ D2O):
d 143.9, 138.0, 135.3, 134.3, 132.9, 132.8, 131.5, 129.7,
128.3, 126.2, 123.4, 122.0, 120.4, 117.1, 111.6, 50.6, 48.7, 47.3, 46.9,
carboline hydro-chloride salt (4d)
Yield 40%; IR (KBr, cmꢁ1) v: 2928, 2677, 1623, 1550, 1461, 1335,
46.7, 23.4, 21.1, 9.3; ESI-MS m/z: 415.4 (M þ 1)þ.
1211, 1138, 1041, 767; 1H NMR (300 MHz, DMSO-d6 þ D2O):
d 8.48 (d,
J ¼ 5.4 Hz,1H, H-3), 8.39 (d, J ¼ 5.4 Hz,1H, H-4), 8.35 (d, J ¼ 7.8 Hz,1H,
H-8), 7.85 (d, J ¼ 8.1 Hz, 1H, H-5), 7.67 (t, J ¼ 8.1 Hz, 1H, H-7), 7.34 (t,
J ¼ 7.2 Hz, 1H, H-6), 4.87 (s, 2H, CH2NHCH2CH2CH2CH2N), 4.42 (d,
5.4.13. 1-[N-(2-diethylamino)-ethyl]-methylamino-9-(4-
fluorobenzyl)-b-carboline hydrochloride salt (6a)
Yield 60%; IR (KBr, cmꢁ1) v: 2976, 2662, 1624, 1494, 1457, 1337,
J
¼
7.5 Hz, 2H, NCH2CH(CH3)2), 3.22 (t,
J
¼
6
Hz, 2H,
1297, 1246, 1199, 1134, 1029, 749; 1H NMR (300 MHz, DMSO-
NHCH2CH2CH2CH2N), 3.05e3.12 (m, 6H, NHCH2CH2CH2CH2N),
2.07e2.20(m, 1H, NCH2CH(CH3)2), 1.81 (br s, 4H,
d6 þ D2O): 8.45 (d, J ¼ 5.1 Hz, 1H, H-3), 8.35e8.39 (m, 2H, H-4, H-
d
8), 7.72 (d, J ¼ 8.4 Hz, 1H, H-5), 7.63 (t, J ¼ 7.5 Hz, 1H, H-7), 7.36 (t,
J ¼ 7.5 Hz, 1H, H-6), 7.08e7.14 (m, 2H, 4-fluorophenyl-H), 6.99e7.04
(m, 2H, 4-fluorophenyl-H), 5.91 (s, 2H, NCH2-4-fluorophenyl), 4.79
NHCH2CH2CH2CH2N), 1.21 (t, J ¼ 7.2 Hz, 6H, N(CH2CH3)2), 0.86 (d,
J¼ 6.3 Hz,6H,NCH2CH(CH3)2);13CNMR(75 MHz, D2O):
d 145.3,136.1,

Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
5135
(s, 2H, CH2NHCH2CH2N), 3.49 (m, 4H, NHCH2CH2N) 3.13e3.20 (m,
4H, N(CH2CH3)2), 1.24 (t, J ¼ 7.2 Hz, 6H, CH3); 13C NMR (75 MHz,
J ¼ 5.4 Hz, 1H, H-3), 8.37e8.39 (m, 2H, H-4, H-8), 7.70 (d, J ¼ 8.4 Hz,
1H, H-5), 7.64 (t, J ¼ 8.1 Hz, 1H, H-7), 7.36 (t, J ¼ 6.9 Hz, 1H, H-6),
7.28e7.29 (m, 2H, 3-chlorophenyl-H), 6.98 (s, 1H, 3-chlorophenyl-
H), 6.83e6.87 (m, 1H, 3-chlorophenyl-H), 5.92 (s, 2H, NCH2-
3-chlorophenyl), 4.68 (s, 2H, CH2NHCH2CH2CH2N), 3.07e3.14 (m,
4H, NHCH2CH2CH2N), 2.73 (s, 6H, CH3), 2.01e2.11 (m, 2H,
D2O):
d 163.5, 160.2, 144.1, 134.8, 133.3, 133.1, 132.1, 131.0, 127.5,
127.4, 122.8, 122.2, 119.2, 116.9, 116.1, 115.8, 110.4, 49.4, 48.2, 47.9,
46.8, 43.1, 8.6; ESI-MS m/z: 405.4 (M þ 1)þ.
5.4.14. 1-[N-(3-dimethylamino)-propyl]-methylamino-9-(4-
NHCH2CH2CH2N); 13C NMR (75 MHz, DMSO-d6 þ D2O):
d 144.2,
fluorobenzyl)-
b
-carboline hydrochloride salt (6b)
140.1,134.4,134.3,134.2,133.9,132.2,131.6,131.1,128.4,126.3,125.0,
123.8, 122.5, 120.1, 118.0, 111.7, 54.1, 48.4, 45.9, 45.4, 42.8, 21.5; ESI-
MS m/z: 407.4 (M þ 1)þ.
Yield 35%; IR (KBr, cmꢁ1) v: 2950, 2692, 1625, 1547, 1505, 1466,
1384, 1332, 1290, 1222, 1158, 1130, 1047, 1019, 751; 1H NMR
(300 MHz, DMSO-d6 þ D2O):
d
8.49 (d, J ¼ 5.1 Hz, 1H, H-3),
8.38e8.42 (m, 2H, H-4, H-8), 7.77 (d, J ¼ 8.4 Hz, 1H, H-5), 7.63e7.69
(m, 1H, H-7), 7.37 (t, J ¼ 7.2 Hz, 1H, H-6), 7.08e7.14 (m, 2H,
4-fluorophenyl-H), 6.99e7.04 (m, 2H, 4-fluorophenyl-H), 5.93 (s,
2H, NCH2-4-fluorophenyl), 4.70 (s, 2H, CH2NHCH2CH2CH2N),
3.11e3.18 (m, 4H, NHCH2CH2CH2N), 2.74 (s, 6H, CH3), 2.06e2.16 (m,
5.4.19. 1-[N-(3-diethylamino)-propyl]-methylamino-9-(3-
chlorobenzyl)-b-carboline hydrochloride salt (7c)
Yield 55%; IR (KBr, cmꢁ1) v: 2971, 2927, 2881, 2752, 2534, 2447,
1623, 1562, 1468, 1432, 1341, 1288, 1195, 1137, 1092, 1040, 772; 1H
NMR (300 MHz, DMSO-d6 þ D2O): 8.66e8.67 (d, J ¼ 5.7 Hz, 1H, H-
d
2H, NHCH2CH2CH2N); 13C NMR (75 MHz, DMSO-d6 þ D2O):
d
163.7,
3), 8.60 (d, J ¼ 5.7 Hz, 1H, H-4), 8.49 (d, J ¼ 7.8 Hz, 1H, H-8), 7.80 (d,
J ¼ 8.4 Hz,1H, H-5), 7.71 (t, J ¼ 7.8 Hz, 1H, H-7), 7.41 (t, J ¼ 7.5 Hz,1H,
H-6), 7.28e7.29 (m, 2H, 3-chlorophenyl-H), 7.14 (s, 1H, 3-
chlorophenyl-H), 6.93 (t, J ¼ 3.9 Hz, 1H, 3-chlorophenyl-H), 6.06
(s, 2H, NCH2-3-chlorophenyl), 4.77 (s, 2H, CH2NHCH2CH2CH2N),
3.16e3.27 (m, 4H, NHCH2CH2CH2N), 3.05e3.13 (m, 4H,
NHCH2CH2CH2N(CH2CH3)2), 2.13e2.23 (m, 2H, NHCH2CH2CH2N),
1.22 (t, J ¼ 7.2 Hz, 6H, CH3); 13C NMR (75 MHz, DMSO-d6 þ D2O):
160.4, 144.1, 134.5, 134.3, 134.0, 133.7, 132.0, 131.9, 128.6, 128.5,
123.6, 122.3, 120.4, 117.6, 116.7, 116.4, 111.7, 54.2, 48.2, 46.3, 45.4,
42.8, 21.5; ESI-MS m/z: 391.4 (M þ 1)þ.
5.4.15. 1-[N-(3-diethylamino)-propyl]-methylamino-9-(4-
fluorobenzyl)-b-carboline hydrochloride salt (6c)
Yield 40%; IR (KBr, cmꢁ1) v: 2944, 2683, 1625, 1506, 1465, 1385,
1336, 1290, 1224, 1159, 1134, 1045, 754; 1H NMR (300 MHz, DMSO-
d 144.0, 140.4, 134.8, 134.4, 134.3, 133.5, 132.3, 131.8, 131.6, 128.3,
d6 þ D2O):
d
8.44 (d, J ¼ 5.1 Hz,1H, H-3), 8.31e8.37 (m, 2H, H-4, H-8),
126.3, 125.0, 123.6, 122.3, 120.4, 117.5, 111.7, 48.5, 48.3, 47.1, 46.4,
7.72(d, J¼ 8.4Hz,1H, H-5), 7.63(t,J¼ 7.5Hz,1H, H-7), 7.35(t, J¼ 7.5 Hz,
1H, H-6), 7.09e7.13 (m, 2H, 4-fluorophenyl-H), 6.96e7.00 (m, 2H, 4-
fluorophenyl-H), 5.89 (s, 2H, NCH2-4-fluorophenyl), 4.68 (s, 2H,
CH2NHCH2CH2CH2N), 3.05e3.14 (m, 8H, NHCH2CH2CH2N(CH2CH3)2),
45.5, 20.9, 9.3; ESI-MS m/z: 435.4 (M þ 1)þ.
5.4.20. 1-[N-(4-diethylamino)-butyl]-methylamino-9-(3-
chlorobenzyl)-b-carboline hydrochloride salt (7d)
2.03e2.09 (m, 2H, NHCH2CH2CH2N), 1.21 (t, J ¼ 7.2 Hz, 6H, CH3); 13
C
Yield 50%; IR (KBr, cmꢁ1) v: 2939, 2671,1624,1464,1337,1197,1041,
NMR (75 MHz, D2O):
d
163.5, 160.3, 144.3, 135.6, 134.0, 133.3, 132.3,
770; 1H NMR (300 MHz, DMSO-d6 þ D2O):
d 8.55 (br s, 2H, H-3, H-4),
131.7, 128.0, 127.6, 127.5, 122.9, 122.3, 119.4, 117.6, 116.3, 116.0, 110.4,
8.43 (d, J ¼ 7.8 Hz, 1H, H-8), 7.75 (d, J ¼ 8.4 Hz, 1H, H-5), 7.69 (t,
J ¼ 6.9 Hz, 1H, H-7), 7.39 (t, J ¼ 7.2 Hz, 1H, H-6), 7.28e7.30 (m, 2H, 3-
chlorophenyl-H), 7.09 (s, 1H, 3-chlorophenyl-H), 6.90e6.91 (m, 1H,
3-chlorophenyl-H), 6.00 (s, 2H, NCH2-3-chlorophenyl), 4.72 (s, 2H,
CH2NHCH2CH2CH2CH2N), 3.01e3.09 (m, 8H, NHCH2CH2CH2CH2
N(CH2CH3)2), 1.73 (br s, 4H, NHCH2CH2CH2CH2N), 1.20 (t, J ¼ 6.9 Hz,
48.7, 47.9, 47.6, 46.1, 45.7, 21.1, 8.7; ESI-MS m/z: 419.4 (M þ 1)þ.
5.4.16. 1-[N-(4-diethylamino)-butyl]-methylamino-9-(4-
fluorobenzyl)-b-carboline hydrochloride salt (6d)
Yield 38%; IR (KBr, cmꢁ1) v: 2946, 2683, 1625, 1504, 1462, 1337,
1221, 752; 1H NMR (300 MHz, DMSO-d6 þ D2O):
d
8.51 (br s, 2H, H-3,
6H, CH3); 13C NMR (75 MHz, DMSO-d6 þ D2O):
d 143.5, 140.6, 135.7,
H-4), 8.37 (d, J ¼ 7.8 Hz,1H, H-8), 7.63e7.74 (m, 2H, H-5, H-7), 7.36 (t,
J ¼ 7.5 Hz,1H, H-6), 7.00e7.10 (m, 4H, 4-fluorophenyl-H), 5.92 (s, 2H,
NCH2-4-fluorophenyl), 4.71 (s, 2H, CH2NHCH2CH2CH2CH2N),
3.00e3.10 (m, 8H, NHCH2CH2CH2CH2N(CH2CH3)2), 1.72 (br s, 4H,
NHCH2CH2CH2CH2N),1.81 (t, J ¼ 6.9 Hz, 6H, CH3); 13C NMR (75 MHz,
134.3, 134.2, 133.1, 132.7, 131.7, 131.4, 128.3, 126.2, 124.9, 123.3, 122.1,
120.5,117.0,111.5, 50.7, 48.2, 47.4, 46.9 (2C), 23.4, 21.1, 9.3; ESI-MS m/z:
449.4 (M þ 1)þ.
5.4.21. 1-[N-(2-diethylamino)-ethyl]-methylamino-9-(3-
DMSO-d6 þ D2O):
d
163.6, 160.4, 143.6, 135.6, 134.1, 132.8, 131.4,
phenylpropyl)-
Yield 56%; IR (KBr, cmꢁ1) v: 2932, 2615, 1622, 1571, 1490, 1451,
1386, 1336, 1208, 1135, 1042, 773; 1H NMR (500 MHz, D2O):
8.18
b-carboline hydrochloride salt (8a)
128.4, 128.3, 123.3, 122.1, 120.5, 117.0, 116.7, 116.4, 111.4, 50.8, 48.0,
47.4, 47.0 (2C), 23.4, 21.1, 9.3; ESI-MS m/z: 433.4 (M þ 1)þ.
d
(d, J ¼ 7.5 Hz,1H, H-3), 8.12 (d, J ¼ 7.5 Hz, 1H, H-4), 7.89 (d, J ¼ 10 Hz,
1H, H-8), 7.52 (t, J ¼ 9.5 Hz, 1H, H-7), 7.13e7.19 (m, 5H, H-5, H-6, Ph-
H), 6.95 (d, J ¼ 8.5 Hz, 2H, Ph-H), 4.13 (s, 2H, CH2NHCH2CH2N), 4.03
(t, J ¼ 9.5 Hz, 2H, NCH2CH2CH2Ph), 3.37 (t, J ¼ 8.5 Hz, 2H,
NHCH2CH2N), 3.24e3.27 (m, 4H, N(CH2CH3)2), 3.10 (t, J ¼ 8.5 Hz,
2H, NHCH2CH2N), 2.48 (t, J ¼ 8 Hz, 2H, NCH2CH2CH2Ph), 1.74e1.79
(m, 2H, NCH2CH2CH2Ph), 1.30 (t, J ¼ 9 Hz, 6H, CH3); 13C NMR
5.4.17. 1-[N-(2-diethylamino)-ethyl]-methylamino-9-(3-
chlorobenzyl)-b-carboline hydrochloride salt (7a)
Yield47%;IR(KBr, cmꢁ1)v:2971, 2649,1623,1465,1434,1336,1195,
772; 1H NMR (300MHz, DMSO-d6 þ D2O):
d 8.43e8.49 (m, 2H, H-3, H-
4), 8.29 (d, J ¼ 7.8 Hz,1H, H-8), 7.55e7.63 (m, 2H, H-5, H-7), 7.29e7.34
(m, 1H, H-6), 7.17e7.25 (m, 2H, 3-chlorophenyl-H), 6.89e6.93 (m, 2H,
3-chlorophenyl-H), 5.88 (s, 2H, NCH2-3-chlorophenyl), 4.77 (s, 2H,
CH2NHCH2CH2N), 3.47e3.54 (m, 4H, NHCH2CH2N), 3.13e3.20 (m, 4H,
NHCH2CH2N(CH2CH3)2), 1.21 (d, J ¼ 7.2 Hz, 6H, CH3); 13C NMR
(125 MHz, D2O): d 143.8, 140.7, 134.5, 134.1, 132.1, 131.9, 129.0, 128.7,
128.5, 126.4, 122.6, 121.9, 119.1, 116.3, 110.7, 50.1, 47.8, 46.6, 44.3,
43.2, 31.7, 30.6, 8.1; ESI-MS m/z: 415.4 (M þ 1)þ.
(75 MHz, DMSO-d6 þ D2O):
d 143.4, 140.1, 135.3, 134.3, 133.9, 132.9
(2C),131.6 (2C),128.4,125.9,124.9,123.2,122.3,120.4,117.0,111.3, 48.1,
5.4.22. 1-[N-(3-dimethylamino)-propyl]-methylamino-9-(3-
47.6, 47.5, 42.3, 9.3; ESI-MS m/z: 421.1 (M þ 1)þ.
phenylpropyl)-b-carboline hydrochloride salt (8b)
Yield 40%; IR (KBr, cmꢁ1) v: 2924, 2684, 1625, 1458, 1383, 1338,
5.4.18. 1-[N-(3-dimethylamino)-propyl]-methylamino-9-(3-
1052, 752; 1H NMR (500 MHz, DMSO-d6 þ D2O):
d 8.47 (d,
chlorobenzyl)-
b
-carboline hydrochloride salt (7b)
J ¼ 5.4 Hz, 1H, H-3), 8.34e8.40 (m, 2H, H4, H-8), 7.65e7.74 (m, 2H,
H-5, H-7), 7.32e7.38 (m, 1H, H-6), 7.16e7.27 (m, 5H, Ph-H), 4.86 (s,
2H, CH2NHCH2CH2CH2N), 4.62 (t, J ¼ 7.5 Hz, 2H, NCH2CH2CH2Ph),
Yield 41%; IR (KBr, cmꢁ1) v: 2969, 2648, 1622, 1463, 1336, 1196,
1038, 771; 1H NMR (300 MHz, DMSO-d6 þ D2O):
d 8.47 (d,

5136
Z. Chen et al. / European Journal of Medicinal Chemistry 46 (2011) 5127e5137
3.19e3.25 (m, 4H, NHCH2CH2CH2N), 2.69e2.77 (m, 8H, CH3,
NCH2CH2CH2Ph), 2.16e2.26 (m, 2H, NCH2CH2CH2Ph), 2.02e2.10 (m,
excess of DNA by means of a dispenser equipped with a 25ul
syringe and adequate Teflon tubing.
2H, NCH2CH2CH2Ph); 13C NMR (100 MHz, D2O):
d 144.5, 140.5,
136.2, 133.5, 132.5, 131.7, 128.7, 128.3, 126.8, 126.4, 123.0, 122.2,
119.4, 117.7, 111.0, 54.2, 46.0, 45.2, 44.4, 42.9, 31.8, 29.8, 21.5; ESI-MS
m/z: 401.4 (M þ 1)þ
5.7. Determination of
6Tm
Tm measurements were performed using a Shimadzu UV
2501PC Spectrometer and following the methods described by Xiao
et al. [5] with slight modification. Experiments were carried out in
PE buffer (1 mM Na2HPO4, 0.1 mM EDTA, pH 7.4) in a thermostati-
cally controlled cell hold, and the quartz cuvette (1 cm path length)
was heated by circulating water at a heating rate of 0.5 ꢀC/min from
25 to 95 ꢀC. Doxorubicin Hydrochloride was used as standards. In
all cases, the ratio of compound to CT-DNA is 0.2.
5.4.23. 1-[N-(3-diethylamino)-propyl]-methylamino-9-(3-
phenylpropyl)-
Yield 55%; IR (KBr, cmꢁ1) v: 2933, 2669, 1624, 1493, 1457, 1385,
1337,1042, 753; 1HNMR (500 MHz, D2O):
8.45e8.49 (m, 2H H-3, H-
b-carboline hydrochloride salt (8c)
d
4), 8.30 (d, J ¼ 8 Hz, 1H, H-8), 7.84 (t, J ¼ 7 Hz, 1H, H-7), 7.65 (d,
J ¼ 8.5 Hz, 1H, H-5), 7.49 (t, J ¼ 8 Hz, 1H, H-6), 7.25e7.32 (m, 3H, Ph-
H), 7.12 (d, J ¼ 6.5 Hz, 2H, Ph-H), 4.65 (s, 2H, CH2NHCH2CH2CH2N),
4.49 (t, J ¼ 7.5 Hz, 2H, NCH2CH2CH2Ph), 3.27e3.33 (m, 6H,
NHCH2CH2CH2N(CH2CH3)2), 3.13 (t, J ¼ 7.5 Hz, 2H, NHCH2CH2CH2N),
5.8. Fluorescence spectroscopy
2.71 (t,
J
¼
7 Hz, 2H, NCH2CH2CH2Ph), 2.13e2.24 (m, 4H,
NCH2CH2CH2Ph, NHCH2CH2CH2N), 1.35 (t, J ¼ 7 Hz, 6H, CH3); 13C
Fluorescence spectral measurement was recorded using 10 mM
of the fluorescent drugs incubated in 1 ml of PE buffer in the
NMR (125 MHz, D2O): d 144.4, 140.6, 135.8, 133.5, 132.3, 131.9, 128.7,
presence or absence of increasing concentrations of CT-DNA (0, 15,
30, 45, 60, 75 and 90 mM) in a quartz cuvette of 10 mm path length.
The corresponding changes in the fluorescence intensity of the
selected compounds were observed on a Shimadzu RF-5310PC
spectrofluorometer at a fluorescence excitation wavelength of
372 nm.
128.4, 127.2, 126.4, 122.9, 122.1, 119.5, 117.5, 110.9, 48.4, 47.7, 46.2,
45.3, 44.4, 31.8, 29.8, 21.0, 8.3; ESI-MS m/z: 429.4 (M þ 1)þ.
5.4.24. 1-[N-(4-diethylamino)-butyl]-methylamino-9-(3-
phenylpropyl)-b-carboline hydrochloride salt (8d)
Yield 59%; IR (KBr, cmꢁ1) v: 2938, 2667, 1625, 1455, 1337, 1292,
1143, 1041, 762; 1H NMR (300 MHz, DMSO-d6 þ D2O):
d 8.43e8.48
(m, 2H, H-3, H-4), 8.31 (d, J ¼ 7.8 Hz, 1H, H-8), 7.63e7.70 (m, 2H,
Acknowledgment
H-5, H-7), 7.31e7.36 (m, 1H, H-6), 7.11e7.22 (m, 5H, Ph-H), 4.77 (s,
2H, CH2NHCH2CH2CH2CH2N), 4.56 (t,
J
¼
6.9 Hz, 2H,
This work was supported by MEGA-Project (2009ZX09102-004)
and the Fundamental Research Funds for the Central Universities.
NHCH2CH2CH2Ph), 3.05e3.12 (m, 8H, NHCH2CH2CH2CH2N
(CH2CH3)2), 2.65 (t, J ¼ 7.2 Hz, 2H, NCH2CH2CH2Ph), 1.97e2.06 (m,
2H, NCH2CH2CH2Ph), 1.77 (br s, 4H, NHCH2CH2CH2CH2N), 1.19 (t,
J ¼ 7.2 Hz, 6H, CH3); 13C NMR (75 MHz, DMSO-d6 þ D2O):
d 143.5,
References
141.4,134.5,133.6,133.0,132.0,131.4,129.1,129.0,126.7,123.2,121.9,
120.3, 117.0, 111.4, 51.0, 47.7, 47.2 (2C), 45.2, 32.7, 31.9, 23.5, 21.2, 9.3;
ESI-MS m/z: 443.5 (M þ 1)þ.
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