Design and synthesis of novel 5,6-disubstituted pyridine-2,3-dione-3- thiosemicarbazone derivatives as potential anticancer agents

Article abstract of DOI:10.1016/j.ejmech.2014.05.001

A series of 5,6-disubstituted pyridine-2,3-dione-3-thiosemicarbazone derivatives(2a-2n) and 5,6-disubstituted pyridine-2,3-dione S-benzyl-3- thiosemicarbazones(3a-3g) were synthesized starting from 2,3-dihydroxypyridine via oxidation-Michael additions, co

Full text of DOI:10.1016/j.ejmech.2014.05.001

European Journal of Medicinal Chemistry 81 (2014) 22e27
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Preliminary communication
Design and synthesis of novel 5,6-disubstituted pyridine-2,3-dione-3-
thiosemicarbazone derivatives as potential anticancer agents
,
b
,
c
,
d
a
,
b
,
,
b
,
,b,c
Wenlin Xie a
, Shimin Xie , Ying Zhou c, Xufu Tang a c, Jian Liu e, Wenqian Yang a
,
*
Minghua Qiu a
,
b
,
c
a School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China
b Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education, Hunan University of Science and Technology, China
c Hunan Provincial University Key Laboratory of QSAR/QSPR, China
d Hunan University of Humanities, Science and Technology, Loudi 417000, China
e Shenzhen Hanyu Pharmaceutical Co., Ltd., Shenzhen 518057, 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 5,6-disubstituted pyridine-2,3-dione-3-thiosemicarbazone derivatives(2a-2n) and 5,6-
Received 6 October 2013
Received in revised form
29 April 2014
Accepted 1 May 2014
Available online 4 May 2014
disubstituted pyridine-2,3-dione S-benzyl-3-thiosemicarbazones(3a-3g) were synthesized starting
from 2,3-dihydroxypyridine via oxidation-Michael additions, condensations and nucleophilic sub-
stitutions. The structures of the compounds were established by IR, 1H NMR, 13C NMR, and HRMS. All
newly synthesized compounds were screened for their anticancer activity against Breast cancer (MCF-7),
Colon cancer (HCT-116) and hepatocellular cancer (BEL7402) cell lines. Bioassay results indicated that
most of the prepared compounds exhibited cytotoxicity against various cancer cells in vitro. Some of the
compounds exhibited promising antiproliferative activity, which were comparable to the positive control
(5-fluorouracil). The structureeactivity relationship was discussed.
Keywords:
2,3-Dihydroxypyridine
Pyridine-2,3-diones
Anticancer activity
Thiosemicarbazone
Ó 2014 Elsevier Masson SAS. All rights reserved.
1. Introduction
part of the skeletal backbone of many therapeutic agents. Of these
heterocycles, pyridinone derivatives possess important biological
Following cardiovascular disease, cancer is the second leading
cause of death in both developed and developing countries [1,2],
the treatment of cancer still remains an important and challenging
problem. For the majority of cancers, chemotherapy has become
one of the methods that are being adopted to treat cancer. Many
compounds have been synthesized with this aim, but their clinical
use has been limited by their relatively high risk of toxicity, because
they lack specificity and produce adverse effects related to the
impact on rapidly dividing noncancerous cells [2,3]. Therefore, to
improve efficacy and decrease the adverse effect potential is one of
the goals in developing new anticancer drugs. Another major goal
for developing new anticancer agents is to overcome cancer resis-
tance to drug treatment that has made many of the currently
available chemotherapeutic agents ineffective [4]. Nitrogen-
containing heterocycles have always constituted a subject of great
interest due to their ubiquity in nature and extensive presence as
activity such as anti-tumor activity [5], leukemia activity [6], anti-
inflammatory activity [7], antimicrobial activity [8], HIV Reverse
Transcriptase inhibitor [9] and antimalarial activity [10], pyridinone
also is found applications in the preparation of deferiprone [11].
pyridinone-fused heterocycles including 4-(phenylthio)-2(1H)-
pyridinones [12], [2R-trans,5Z(E,E)]-1,4-dihydroxy-5-phenyl-3-
[tetrahydro-3-methyl-5-(6-methyl-2,4-octadienylidene)-2H-py-
ran-2-yl]-2(1H)-pyridinone(TMC-69) [13], and 3-amino-4-(pyri-
dine-4-yl)-2(1H)- pyridinone (Amrinone) [14](Fig.1) have attracted
considerable attention.
On the other hand, thiosemicarbazide also exhibits various
biological activities and have attracted considerable pharmaceu-
tical interest [15]. They have been evaluated as antiviral [16],
antibacterial [17], anti-inflammatory [18], antimalarial [19], anti-
leukemic [20] and anticancer [21e23] activities, therefore, the
thiosemicarbazide is a highly efficient pharmacophore in drug
molecular design. Recently, several kinds of thiosemicarbazone
derivatives have been synthesized and their antitumor activities
were also reported [15]. In order to find novel potent pyridinone
antitumor agents, we focused on designing and synthesizing some
new pyridinone derivatives, wherein the active pharmacophores
* Corresponding author. School of Chemistry and Chemical Engineering, Hunan
University of Science and Technology, Xiangtan 411201, China.
E-mail address: xwl2000zsu@163.com (W. Xie).
http://dx.doi.org/10.1016/j.ejmech.2014.05.001
0223-5234/Ó 2014 Elsevier Masson SAS. All rights reserved.

W. Xie et al. / European Journal of Medicinal Chemistry 81 (2014) 22e27
23
Fig. 1. Chemical structure of compound TMC-69 and Amrinone.
thiosemicarbazide has been attached at the 3-position of the pyr-
idine ring, and the antitumor activity of these novel pyridinone
derivatives was screened in vitro in order to get more potent and
selective anticancer agents.
2. Results and discussion
2.1. Chemistry
Scheme 1. Synthesis of the 5,6-disubstituted pyridine-2,3-dione-3-thiosemicarbazone
derivatives(2,3). Reagent and conditions: (a) NaIO3, rt; (b) NH2NHCSNH2, EtOH, H2SO4,
reflux; (c) EtOH, Et3N, reflux.
The synthetic route for 5,6-disubstituted pyridine-2,3-dione-3-
thiosemicarbazone derivatives 2,3 is represented in Scheme 1.
Commercially available 2,3-dihydroxypyridine reacting with aro-
matic amine in the presence of oxidant NaIO3 in one pot via
oxidation-Michael additions gave compound 1. The compounds 1
were characterized by using IR, NMR, and MS techniques. Their
analytical and spectroscopic data agreed with those reported in the
literature [24] for the same compounds. Subsequently, the
condensation of the obtained 5,6-disubstituted pyridine-2,3-
diones 1 with thiosemicarbazide afforded compounds 2aen, and
then the compounds 2 reacted with benzyl bromide in ethanol
medium in the presence of Et3N by nucleophilic substitution re-
action to give 3aeg with good yields. The structures of all the newly
synthesized compounds 2aen and 3aeg were confirmed by 1H
NMR, 13C NMR, IR and HRMS. At the same time, we also observed
that the thiosemicarbazones 2 existed thione and thioltautomeric
from 2A to 2B, because the 1H NMR spectra of thiosemicarbazones 2
exhibit two sets peaks (integral ratio is 1: 0.3). Further evidence for
the existence of thione and thioltautomeric in thiosemicarbazones
2 was obtained from their 13C NMR spectra, which showed a signal
at 178.07e179.86 ppm assigned to (C]S), after the thio-
semicarbazones 2 reacted with benzyl bromide converted to
compound 3, the signals at 178.07e179.86 ppm disappeared.
0.634 ꢀ 0.06
m
M, 1.37 ꢀ 0.04
m
M and 1.12 ꢀ 0.22
mM, respectively.
For HCT-116 cell line, the compounds 2a and 2f displayed the best
inhibitory activity with IC50 1.52 ꢀ 0.18
mM and 0.19 ꢀ 0.02
mM
respectively. For BEL-7402 cell line, the compounds 2a and 2f
exhibited more potent inhibitory activity with corresponding IC50
1.71 ꢀ 0.26
m
M and 0.82 ꢀ 0.03
mM respectively.
From the antitumor activity against three human cancer cell
lines, preliminary structureeactivity relationships of the synthe-
sized compounds were achieved. In general, compared with com-
pounds 2a-2n, substituent on 5, 6-position benzene ring of the
pyridine ring had great effect on the cytotoxicity, for example, the
compounds 2a, 2b, 2c, 2d, 2e, 2f, 2k and 2l displayed the more
Table 1
In vitro antiproliferative activity of 5,6-disubstituted pyridine-2,3-dione-3-
thiosemicarbazone derivatives.
a
Compound
R
IC50
(m
M)
MCF-7b
HCT-116b
BEL-7402b
2a
2b
2c
2d
2e
2f
2g
2h
2i
o-CH3
m-CH3
p-CH3
o-Cl
m-Cl
p-Cl
o-CH3O
m-CH3O
p-CH3O
p-CH3CH2O
p-F
p-Br
m-NO2
H
o-CH3
m-CH3
p-CH3
m-Cl
p-Cl
p-F
0.58 ꢀ 0.06
0.15 ꢀ 0.02
3.06 ꢀ 0.29
3.49 ꢀ 0.11
0.63 ꢀ 0.06
1.37 ꢀ 0.04
10.16 ꢀ 0.98
>50
10.37 ꢀ 0.85
13.69 ꢀ 0.95
1.12 ꢀ 0.22
2.58 ꢀ 0.22
11.11 ꢀ 0.02
7.11 ꢀ 0.11
16.33 ꢀ 0.94
9.34 ꢀ 0.98
13.42 ꢀ 0.94
15.16 ꢀ 0.91
7.72 ꢀ 0.97
7.58 ꢀ 0.97
8.34 ꢀ 0.96
7.08 ꢀ 0.92
1.52 ꢀ 0.18
8.65 ꢀ 0.98
7.04 ꢀ 0.44
3.54 ꢀ 0.25
3.38 ꢀ 0.97
0.19 ꢀ 0.02
20.76 ꢀ 0.85
NTd
22.37 ꢀ 0.37
21.32 ꢀ 0.89
3.72 ꢀ 0.34
2.15 ꢀ 0.029
19.37 ꢀ 0.88
24.65 ꢀ 1.71
13.80 ꢀ 1.26
12.85 ꢀ 0.96
8.27 ꢀ 0.98
11.69 ꢀ 0.93
9.60 ꢀ 0.97
11.45 ꢀ 0.96
14.47 ꢀ 0.83
10.54 ꢀ 1.06
1.71 ꢀ 0.26
2.73 ꢀ 0.26
4.33 ꢀ 0.37
3.42 ꢀ 0.23
2.19 ꢀ 0.18
0.82 ꢀ 0.03
13.39 ꢀ 0.96
NTd
17.76 ꢀ 1.76
31.01 ꢀ 0.87
3.66 ꢀ 0.12
5.84 ꢀ 0.31
8.11 ꢀ 0.99
11.87 ꢀ 1.70
17.09 ꢀ 0.91
8.72 ꢀ 0.97
7.68 ꢀ 0.98
7.16 ꢀ 0.98
17.30 ꢀ 0.74
7.69 ꢀ 0.98
13.13 ꢀ 0.95
11.12 ꢀ 0.72
2.2. Biological activity
The in vitro antitumor activity of the newly synthesized com-
pounds 2aen and 3aeg was evaluated against a panel of three
human cancer cell lines, including MCF-7 (breast adenocarcinoma
cell), HCT116 (colon carcinoma cell) and BEL-7402 (hepatoma car-
2j
2k
2l
cinoma
cell)
by
MTT
(3-(4,5-dimethylthiazol-2-yl)-2,5-
diphenyltetrazolium bromide) method [25]. The inhibitory activ-
ities (IC50) are summarized in Table 1 and the well-known anti-
cancer drug 5-fluorouracil was used as positive control [26,27].
From the screening results in Table 1, it was observed that most of
the synthesized compounds exhibited more potent cytotoxic ac-
2m
2n
3a
3b
3c
3d
3e
3f
tivities (IC50 < 7.0 mM) against the three human cancer cell lines in
comparison with 5-FU. Special compounds 2a, 2b, 2c, 2d, 2e, 2f, 2k
and 2l displayed higher cytotoxicity activity than 5-FU against all
three human cancer cell lines, the compound 2f showed promising
antiproliferative activity with IC50 values in the range of 0.19e
3g
5-FU
o-CH3O
a
IC50 is the concentration of compound required to inhibit the cell growth by
50% compared to an untreated control.
1.37
mM. Although most compounds showed potent antitumor ac-
tivity (IC50 < 7.0
m
M), some compounds exhibited selectivity be-
b
MCF-7 cells were the human breast adenocarcinoma cells, HCT-116 cells were
tween the three human cancer cell lines. For MCF-7 cell line, the
compounds 2a, 2b, 2e, 2f and 2k, showed the more potent inhibi-
the human colon carcinoma cells and BEL-7402 cells were the human hepatoma
carcinoma cells.
d
tory activity with IC50 0.58
ꢀ
0.06
mM, 0.15
ꢀ
0.02
m
M,
NT means not tested.

24
W. Xie et al. / European Journal of Medicinal Chemistry 81 (2014) 22e27
potent antitumor activity than the compound with no substituent
(2n) against the three human cancer cell lines. Among these
compounds, compounds with methyl group substituent (2a, 2b and
2c) and halogen substituent (2d, 2e, 2f, 2k and 2l) on the benzene
ring showed stronger inhibitory activity than the compound with
methoxyl, ethyoxyl and nitryl substituent on the benzene ring (2g,
2h, 2i, 2j and 2m). In comparison to compounds 2a, 2b and 2c, the
compound 2g, 2h, 2i and 2j (R ¼ p-CH3CH2O), with bulky group on
the benzene ring, exhibited greater reduction in the inhibitory ac-
tivity. On the other hand, the introduction of benzyl group on sulfur
atom of thiosemicarbazones (3ae3g) also lowered the inhibitory
activity. We found that most of the compounds 2 without substit-
uent on sulfur atom of thiosemicarbazone have higher cytotoxicity
than the compounds 3 with benzyl groups. Furthermore, from the
above-mentioned analysis, it can be concluded that the benzylation
of the thiosemicarbazones reduced the biological activity, and
methyl or chloro or fluoro or bromo substituted benzene ring in
compounds 2 were found to be the most favorable for the anti-
tumor activity.
4.3. General procedure for the synthesis of 5,6-disubstituted
pyridine-2,3-dione-3-thiosemicarbazone derivatives (2)
To
a solution of 5,6-disubstituted pyridine-2,3-diones 1
(4 mmol) in anhydrous ethanol (60 ml) were added thio-
semicarbazide (4.2 mmol) and sulfuric acid (0.04 mmol). The re-
action mixture was refluxed and the reaction monitored by TLC,
after the completion of the reaction, 200 ml water was added, and
the precipitate formed was isolated by filtration. The resulting
crude product was purified by recrystallization with ethanol to
afford the desired compounds 2.
4.3.1. (Z)-5,6-di(o-methylanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2a
Yellow solid; yield 76.3%; mp. 208e209 ꢂC; 1H NMR (DMSO-d6,
500 MHz)
d: 2.14 (s, 3H, eCH3), 2.25 (s, 3H, eCH3), 6.86 (d,
J ¼ 8.0 Hz, 1H, AreH), 7.04e7.33(m, 8H, AreH, pyridine-H), 7.95 (s,
1H, eNH2), 8.30 (s, 1H, eNH2), 8.65 (s, 1H, eNHe), 10.65 (s, 1H, e
NHe), 12.86 (s, 1H, ]NeNHe); 13C NMR (DMSO-d6, 125 MHz)
d:
17.96, 18.19, 101.35, 120.22, 124.65, 125.70, 125.84, 127.12, 127.30,
129.50, 130.93, 131.48, 133.65, 137.06, 138.45, 141.43, 145.31, 159.70,
160.44, 178.14; IR (KBr) v: 3321, 2971, 2924, 2857, 1695, 1648, 1613,
1596, 1517, 1484, 1461, 1387, 1317, 1245, 1156, 1107, 1045 cmꢁ1; MS
(ESI, m/z): 393 (M þ H)þ. HRMS (ESI, m/z) calcd for [C20H21N6OS]þ
(M þ H)þ 393.1492, found 393.1501.
3. Conclusions
In summary, a series of novel 5,6-disubstituted pyridine-2,3-
dione-3-thiosemicarbazone derivatives (2ae2n; 3ae3g) were
synthesized and screened for antiproliferative activity against MCF-
7, HCT-116 and BEL-7402 three human cancer cell lines. The pre-
liminary investigation showed most of them displayed higher ac-
tivity against all three human cancer cell lines than 5-FU. The
results of the structureeactivity relationships indicated that the
benzylation of the thiosemicarbazones reduced the biological ac-
tivity, and methyl or chloro or fluoro or bromo substituted benzene
ring in compounds 2 were found to be the most favorable for the
antitumor activity, which will encourage us to further design more
potent antitumor agents. These findings also have conducted us to
further investigate their detailed pharmacological mechanisms.
4.3.2. (Z)-5,6-di(m-methylanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2b
Orange solid; yield 78.6%; mp. 145e146 ꢂC; 1H NMR (DMSO-d6,
500 MHz) d: 2.32 (s, 3H, eCH3), 2.33 (s, 3H, eCH3), 6.46 (s, 1H, Are
H), 6.76 (d, J ¼ 8.0 Hz, 2H, AreH), 6.90e7.29 (m, 6H, AreH, pyridine-
H), 8.05 (s, 1H, eNH2), 8.29 (s, 1H, eNH2), 8.67 (s, 1H, eNHe), 10.39
(s, 1H, eNHe), 12.87 (s, 1H, ]NeNHe); 13C NMR (CDCl3, 125 MHz)
d: 21.56, 21.60, 94.43, 118.48, 122.90, 123.04, 124.47, 124.89, 125.47,
126.29, 129.55, 129.68, 130.58, 135.65, 136.77, 139.17, 145.19, 156.09,
161.45, 179.02; IR (KBr) v: 3301, 3256, 3172, 3026, 2921, 1660, 1643,
1620, 1602, 1588, 1522, 1459, 1333, 1328, 1281, 1258, 1237,
1119 cmꢁ1; MS (ESI, m/z): 393 (M þ H)þ. HRMS (ESI, m/z) calcd for
[C20H21N6OS]þ (M þ H)þ 393.1492, found 393.1510.
4. Experimental section
4.1. General
4.3.3. (Z)-5,6-di(p-methylanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2c
Melting points were determined in open capillaries and were
uncorrected. IR spectra were recorded on a PE-2000 spectrometer
in KBr pellets and are reported in cmꢁ1. All NMR spectra were
recorded on a Bruker AV-II 500 MHz NMR spectrometer, operating
at 500 MHz for 1H, and 125 MHz for 13C, TMS was used as an in-
ternal reference for 1H and 13C chemical shifts and CDCl3 and DMSO
were used as solvent. Mass spectra were collected on a Waters Xevo
Q-TOF HRMS instrument. 2,3-dihydroxypyridine was purchased
from Aldrich; other commercially available materials were pur-
chased from Aladdin-Reagent and Sinopharm Chemical Reagent,
and were used without further purification.
Chinese red solid; yield 85.6%; mp. 168e169 ꢂC; 1H NMR(DMSO-
d6, 500 MHz) d: 2.32 (s, 6H, eCH3), 6.36 (s, 1H, AreH), 6.87e7.32 (m,
8H, AreH, pyridine-H), 8.12 (s, 1H, eNH2), 8.32 (s, 1H, eNH2), 8.69
(s, 1H, eNHe), 10.47 (s, 1H, eNHe), 12.87 (s, 1H, ]NeNHe); 13C
NMR (DMSO-d6, 125 MHz) d: 20.94, 21.10, 93.60, 102.10, 121.35 (2C),
122.87 (2C), 130.20 (2C), 133.35 (2C), 133.65, 134.56, 136.97, 143.09,
143.86, 159.59, 160.22, 179.86; IR (KBr) v: 3235, 3393, 3235, 3154,
2920, 2861, 1667, 1634, 1606, 1520, 1467, 1394, 1325, 1308, 1239,
1114 cmꢁ1; MS (ESI, m/z): 393 (M þ H)þ. HRMS (ESI, m/z) calcd for
[C20H21N6OS]þ (M þ H)þ 393.1492, found 393.1499.
4.2. Synthesis of 5,6-disubstituted pyridine-2,3-dione (1)
4.3.4. (Z)-5,6-di(o-chloroanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2d
According to the literature method [24], sodium iodate (1.38 g,
7.0 mmol) was added to a solution of 2,3-dihydroxypyridine (0.70 g,
6.3 mmol) in 0.5 mol/L phosphate-buffered saline (35.0 ml, pH 6.0)
and 125 ml methanol. After stirring for 15 min, the appropriate
aromatic amine (12.6 mmol) was added and the resulting mixture
was stirred at room temperature. The progress of the reaction was
monitored by TLC. After completion of the reaction, 150 ml water
was added, and the precipitate formed was isolated by filtration.
The resulting crude product was purified by column chromatog-
raphy on silica gel to afford the corresponding 1.
Red solid; yield 80.1%; mp. 247e248 ꢂC; 1H NMR (DMSO-d6,
500 MHz)
d
: 6.34 (s, 1H, AreH), 7.06 (d, J ¼ 8.0 Hz, 1H, AreH), 7.34e
7.63 (m, 7H, AreH, pyridine-H), 8.09 (s, 1H, eNH2), 8.30 (s, 1H, e
NH2), 8.51 (s, 1H, eNHe), 11.32 (s, 1H, eNHe), 12.84 (s, 1H, ]Ne
NHe); 13C NMR (DMSO-d6, 125 MHz)
d: 95.89, 115.36, 122.72,
124.95, 125.37, 126.73, 127.21, 130.10, 130.92, 131.12, 132.47, 132.81,
134.73, 141.75, 149.54, 157.38, 160.27, 178.07; IR (KBr) v: 3333, 3275,
3170, 1602, 1591, 1533, 1468, 1448, 1323, 1286, 1236, 1120 cmꢁ1; MS
(ESI, m/z): 433 (M
þ
H)þ. HRMS (ESI, m/z) calcd for
[C18H15Cl2N6OS]þ (M þ H)þ 433.0400, found 433.0408.

W. Xie et al. / European Journal of Medicinal Chemistry 81 (2014) 22e27
25
4.3.5. (Z)-5,6-di(m-chloroanilino) pyridine-2,3-dione-3-
139þ0, 1356, 1291, 1245, 1182, 1106 cmꢁ1; MS (ESI, m/z): 425
(M
thiosemicarbazone 2e
H)þ. HRMS (ESI, m/z) calcd for [C20H21N6O3S]þ (M þ H)þ
Yellow solid; yield 75.8%; mp. 249e250 ꢂC; 1H NMR (DMSO-d6,
425.1390, found 425.1398.
500 MHz) d: 6.55 (s, 1H, AreH), 7.01e7.39 (m, 8H, AreH, pyridine-
H), 8.37 (s, 1H, eNH2), 8.44 (s, 1H, eNH2), 8.81 (s, 1H, eNHe), 11.04
4.3.10. (Z)-5,6-di(p-ethoxyanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2j
(s, 1H, eNHe), 12.92 (s, 1H, ]NeNHe); 13C NMR (DMSO-d6,
125 MHz)
d
: 96.21, 105.27, 120.00, 120.31, 120.65, 121.27, 121.79,
Red solid; yield 80.1%; mp. 124e125 ꢂC; 1H NMR (DMSO-d6,
122.87, 124.30, 130.17, 131.25, 131.34, 134.01, 134.07, 142.38, 148.45,
160.44, 178.46; IR (KBr) v: 3324, 3297, 3253, 3170, 3024, 2824, 1664,
1620, 1589, 1513, 1463, 1395, 1327, 1271, 1239, 1123 cmꢁ1; MS (ESI,
m/z): 433 (M þ H)þ. HRMS (ESI, m/z) calcd for [C18H15Cl2N6OS]þ
(M þ H)þ 433.0400, found 433.0405.
500 MHz)
d
: 1.24 (t, J ¼ 8.0 Hz, 3H, eCH3), 1.27 (t, J ¼ 8.0 Hz, 3H, e
CH3), 3.99 (q, J ¼ 8.5 Hz, 2H, eCH2e), 4.07 (q, J ¼ 8.5 Hz, 2H, eCH2e
), 6.23 (s, 1H, AreH), 7.14e7.33 (m, 8H, AreH, pyridine-H), 8.69 (s,
1H, eNH2), 8.84 (s, 1H, eNH2), 9.43 (s, 1H, eNHe), 11.03 (s, 1H, e
NHe), 12.80 (s, 1H, ]NeNHe); 13C NMR (DMSO-d6, 125 MHz)
d:
21.21, 21.50, 32.25, 33.73, 94.98, 115.45(2C), 122.72(2C), 122.84(2C),
125.34, 126.70, 127.76(2C), 130.21, 131.48, 133.09, 136.57, 143.17,
160.27, 178.48; IR (KBr) v: 3334, 3247, 2979, 2809, 1700, 1600, 1510,
147þ4, 1393, 1301, 1243, 1114, 1045 cmꢁ1; MS (ESI, m/z): 453
4.3.6. (Z)-5,6-di(p-chloroanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2f
Yellow solid; yield 86.4%; mp. 226e227 ꢂC; 1H NMR (DMSO-d6,
(M
500 MHz)
d
: 6.47 (s, 1H, AreH), 6.98e7.41 (m, 8H, AreH, pyridine-
H)þ. HRMS (ESI, m/z) calcd for [C22H25N6O3S]þ (M þ H)þ
H), 8.29 (s, 1H, eNH2), 8.32 (s, 1H, eNH2), 8.74 (s, 1H, eNHe), 10.85
453.1703, found 453.1710.
(s, 1H, eNHe), 12.91 (s, 1H, ]NeNHe); 13C NMR (DMSO-d6,
125 MHz)
d
: 95.03, 123.27 (2C), 123.80 (2C), 124.34 (2C), 126.57,
4.3.11. (Z)-5,6-di(p-fluoroanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2k
127.18, 128.78, 129.56 (2C), 130.32, 135.31, 139.63, 157.17, 159.75,
178.55; IR (KBr) v: 3372, 3302, 3233, 3046, 2830, 1668, 1655, 1607,
1539, 1504, 1489, 1345, 1392, 1356, 1301, 1282, 1235, 1118, 1091,
1011 cmꢁ1; MS (ESI, m/z): 433 (M þ H)þ. HRMS (ESI, m/z) calcd for
[C18H15Cl2N6OS]þ (M þ H)þ 433.0400, found 433.0406.
Yellow solid; yield 86.7%; mp. 205e206 ꢂC; 1H NMR (DMSO-d6,
500 MHz)
d
: 6.32 (s, 1H, AreH), 7.20 (d, J ¼ 8.0 Hz, 2H, AreH), 7.26e
7.67 (m, 6H, AreH, pyridine-H), 8.17 (s, 1H, eNH2), 8.27 (s, 1H, e
NH2), 8.68 (s, 1H, eNHe), 10.89 (s, 1H, eNHe), 12.81 (s, 1H, ]Ne
NHe); 13C NMR (DMSO-d6, 125 MHz)
d: 93.83, 100.94, 116.47(2C),
4.3.7. (Z)-5,6-di(o-methoxyanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2g
123.08(2C), 125.00(2C), 127.16(2C), 130.54, 134.24, 136.97, 137.54,
142.61, 158.16,158.50, 160.35, 160.77, 178.90; IR (KBr) v : 3404, 3247,
2979, 2809, 1700, 1600, 1510, 1474, 1393, 1301, 1243, 1114,
1045 cmꢁ1; MS (ESI, m/z): 401 (M þ H)þ. HRMS (ESI, m/z) calcd for
[C18H15F2N6OS]þ (M þ H)þ 401.0991, found 401.0996.
Yellow solid; yield 83.4%; mp. 234e235 ꢂC; 1H NMR (DMSO-d6,
500 MHz) d: 3.76 (s, 3H, eCH3), 3.85 (s, 3H, eCH3), 6.49 (s, 1H, Are
H), 6.89e7.69 (m, 8H, AreH, pyridine-H), 8.00 (s, 1H, eNH2), 8.40 (s,
1H, eNH2), 8.77 (s, 1H, eNHe), 10.75 (s, 1H, eNHe), 12.90 (s, 1H, ]
NeNHe); 13C NMR (DMSO-d6, 125 MHz)
d
: 56.23, 56.29, 94.31,
4.3.12. (Z)-5,6-di(p-bromoanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2l
111.70, 112.01, 119.79, 121.20, 122.55, 123.93, 124.11, 125.84, 128.23,
128.91, 130.36, 133.94, 142.46, 150.29, 150.63, 160.05, 178.32; IR
(KBr) v: 3318, 3233, 2964, 2923, 2853, 1680, 1656, 1625, 1598, 1524,
1491, 1460, 1349, 1322, 1299, 1251, 1219, 1206 cmꢁ1; MS (ESI, m/z):
425 (M þ H)þ. HRMS (ESI, m/z) calcd for [C20H21N6O3S]þ (M þ H)þ
425.1390, found 425.1392.
Yellow solid; yield 80.1%; mp. 191e192 ꢂC; 1H NMR (DMSO-d6,
500 MHz)
d
: 6.47 (s, 1H, AreH), 6.91 (d, J ¼ 8.0 Hz, 2H, AreH), 7.15e
7.56 (m, 6H, AreH, pyridine-H), 8.27 (s, 2H, eNH2), 8.66 (s, 1H, e
NHe), 10.71 (s, 1H, eNHe), 13.02 (s, 1H, ]NeNHe); 13C NMR
(DMSO-d6, 125 MHz) d: 95.17, 114.95, 116.78, 123.70(2C), 124.02(2C),
124.70,130.63, 132.48(2C),135.35(2C), 139.22, 140.13,146.18, 161.01,
178.47; IR (KBr) v: 3372, 3300, 3235, 3049, 2925, 1668, 1654, 1606,
1583, 1537, 1504, 1488, 1345, 1390, 1357, 1302, 1283, 1262, 1233,
1177, 1118, 1071 cmꢁ1; MS (ESI, m/z): 522 (M þ H)þ. HRMS (ESI, m/z)
calcd for [C18H15Br2N6OS]þ (M þ H)þ 520.9389, found 522.9395.
4.3.8. (Z)-5,6-di(m-methoxyanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2h
Orange solid; yield 80.4%; mp. 234e235 ꢂC; 1H NMR (DMSO-d6,
500 MHz) d: 3.75 (s, 3H, eCH3), 3.87 (s, 3H, eCH3), 6.52 (s, 1H, Are
H), 6.71e7.33 (m, 8H, AreH, pyridine-H), 8.05 (s, 1H, eNH2), 8.21 (s,
1H, eNH2), 8.75 (s, 1H, eNHe), 10.61 (s, 1H, eNHe), 12.90 (s, 1H, ]
4.3.13. (Z)-5,6-di(m-nitroanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2m
NeNHe); 13C NMR (DMSO-d6, 125 MHz)
d: 55.53, 55.54, 95.68,
107.80, 109.04, 110.51, 110.56, 113.53, 114.05, 114.33, 130.34, 130.47,
130.67, 133.23, 135.27, 143.33, 147.83, 159.53, 160.38, 178.29; IR
(KBr) v: 3255, 3339, 3571, 3339, 3255, 3166, 2921, 2853, 1681, 1635,
Red solid; yield 80.1%; mp. 273e274 ꢂC; 1H NMR (DMSO-d6,
500 MHz) d: 6.63 (s, 1H, AreH), 7.39e7.97 (m, 8H, AreH, pyridine-
H), 8.09 (s, 1H, eNH2), 8.48 (s, 1H, eNH2), 8.85 (s, 1H, eNHe), 11.27
1608,1590,1519,1473,1333,1321,1265,1218,1172,1150, 1107 cmꢁ1
;
(s, 1H, eNHe), 12.90 (s, 1H, ]NeNHe); 13C NMR (DMSO-d6,
MS (ESI, m/z): 425 (M
þ
H)þ. HRMS (ESI, m/z) calcd for
125 MHz) d: 95.57, 115.44, 117.11, 119.16, 127.03, 128.15, 129.87,
[C20H21N6O3S]þ (M þ H)þ 425.1390, found 425.1396.
130.33, 130.98, 133.35, 134.46, 135.36, 143.67, 148.93, 149.09, 157.79,
160.49, 178.50; IR (KBr) v : 3366, 3333, 1698, 1608, 1522, 1393, 1351,
1298, 1122 cmꢁ1; MS (ESI, m/z): 455 (M þ H)þ. HRMS (ESI, m/z)
calcd for [C18H15N8O5S]þ (M þ H)þ 455.0881, found 455.0888.
4.3.9. (Z)-5,6-di(p-methoxyanilino) pyridine-2,3-dione-3-
thiosemicarbazone 2i
Yellow solid; yield 85.8%; mp. 204e205 ꢂC; 1H NMR (DMSO-d6,
500 MHz)
d
: 3.75 (s, 3H, eCH3), 3.78 (s, 3H, eCH3), 6.16 (s, 1H, Are
4.3.14. (Z)-5,6-dianilino pyridine-2,3-dione-3-thiosemicarbazone
H), 6.92e7.03 (m, 5H, AreH), 7.24 (d, J ¼ 8.5 Hz, 2H, AreH), 7.34 (d,
J ¼ 8.5 Hz, 1H, pyridine-H), 8.07 (s, 1H, eNH2), 8.28 (s, 1H, eNH2),
8.64 (s, 1H, eNHe), 10.53 (s, 1H, eNHe), 12.85 (s, 1H, ]NeNHe);
2n
Chinese red solid; yield 83.4%; mp. 162e163 ꢂC; 1H NMR
(DMSO-d6, 500 MHz)
d
: 6.47 (s, 1H, AreH), 6.97(d, J ¼ 7.5 Hz, 2H,
13C NMR (DMSO-d6, 125 MHz)
d
: 55.67, 55.75, 94.55, 122.76 (2C),
AreH), 7.14e7.47 (m, 8H, AreH, pyridine-H), 8.24 (s, 1H, eNH2),
8.37 (s, 1H, eNH2), 8.73 (s, 1H, eNHe), 10.64 (s, 1H, eNHe), 12.88 (s,
125.06 (2C), 125.45 (2C), 130.98 (2C), 132.33, 132.95, 138.14, 139.08,
156.24, 156.50, 159.84, 160.31, 178.08; IR (KBr) v: 3331, 3264, 3045,
2993, 2931, 2831, 1667, 1655, 1605, 1560, 1537, 1506, 1466, 1354,
1H, ]NeNHe); 13C NMR (DMSO-d6, 125 MHz)
d: 95.92, 121.44(2C),
122.35(2C), 129.70(2C), 129.83(2C), 130.59, 133.37, 135.73, 136.70,

26
W. Xie et al. / European Journal of Medicinal Chemistry 81 (2014) 22e27
139.70, 143.18, 158.77, 160.32, 178.24; IR (KBr) v: 3378, 3310, 3209,
3150, 2973, 2926, 1623, 1594, 1527, 1486, 1454, 1396, 1333, 1310,
1236, 1210, 1091, 1049 cmꢁ1; MS (ESI, m/z): 365 (M þ H)þ. HRMS
(ESI, m/z) calcd for [C18H17N6OS]þ (M þ H)þ 365.1179, found
365.1183.
4.4.4. (3Z, 20E)-5,6-di(m-chloroanilino) pyridine-2,3-dione S-
benzyl-3-isothiosemicarbazone 3d
Yellow solid; yield 72.7%; mp. 156e157 ꢂC; 1H NMR (CDCl3,
500 MHz) d: 4.42 (s, 2H, eCH2e), 6.05 (brs, 2H, eNH2), 6.83 (d,
J ¼ 7.5 Hz, 1H, AreH), 6.97e7.00 (m, 2H, AreH), 7.13e7.20 (m, 3H,
AreH), 7.26e7.38 (m, 7H, AreH), 7.58 (s, 1H, eNHe), 7.67 (s, 1H,
pyridine-H), 8.00 (s,1H, eNHe); 13C NMR (CDCl3, 125 MHz)
d: 34.37,
4.4. General procedure for the synthesis of 5,6-disubstituted
97.54, 118.97, 119.14, 120.78, 121.18, 123.80, 125.51, 127.60, 128.70
(2C), 129.02 (2C), 130.54, 131.27, 133.30, 135.20, 135.87, 136.84,
140.47, 143.79, 143.87, 146.61, 160.48, 165.48; IR (KBr) v: 3301, 2924,
1684, 1518, 1468, 1358, 1386, 1319, 1092 cmꢁ1; MS (ESI, m/z): 523
(M þ H)þ. HRMS (ESI, m/z) calcd for [C25H21Cl2N6OS]þ (M þ H)þ
523.0869, found 523.0879.
pyridine-2,3-dione S-benzyl-3-isothiosemicarbazone derivatives (3)
To
a solution of 5,6-disubstituted pyridine-2,3-dione-3-
thiosemicarbazone 2 (1.0 mmol) in ethanol (30 ml) were added
triethylamine (0.1 ml). The reaction mixture was refluxed for
30 min at 60 ꢂC, followed by immediate addition of benzyl
bromide(1.1 mmol). The reaction mixture was continue to refluxing
for 4h. TLC monitor the reaction process, after the completion of the
reaction, concentrated under vacuum, the precipitate was redis-
solved in ethyl acetate, and The solution was successively washed
with aqueous sodium hydroxide, saturated salt water, dried over
anhydrous sodium sulfate, and evaporated. The resulting crude
product was purified by recrystallization with ethyl acetate to
afford the desired compounds 3.
4.4.5. (3Z, 20E)-5,6-di(p-chloroanilino) pyridine-2,3-dione S-
benzyl-3-isothiosemicarbazone 3e
Yellow solid; yield 85.2%; mp. 165e166 ꢂC; 1H NMR (CDCl3,
500 MHz) d: 4.48 (s, 2H, eCH2e), 6.15 (brs, 2H, eNH2), 6.92 (d,
J ¼ 8.5 Hz, 2H, AreH), 7.15 (s, 1H, AreH), 7.22e7.32 (m, 6H, AreH),
7.38e7.43 (m, 4H, AreH), 7.44 (s, 1H, eNHe), 7.79 (s, 1H, pyridine-
H), 8.23 (s, 1H, eNHe); 13C NMR (DMSO-d6, 125 MHz)
d: 35.06,
114.22, 122.52 (2C), 125.00 (2C), 127.21, 128.22, 129.44 (2C), 129.60
(2C), 130.14 (2C), 130.46 (2C), 134.44, 138.39, 138.43, 141.30, 142.00,
147.74, 155.49, 168.88, 171.35; IR (KBr) v: 3231, 3062, 1604, 1589,
1560, 1491, 1335, 1385, 1251 cmꢁ1; MS (ESI, m/z): 523 (M þ H)þ.
HRMS (ESI, m/z) calcd for [C25H21Cl2N6OS]þ (M þ H)þ 523.0869,
found 523.0876.
4.4.1. (3Z, 20E)-5,6-di(o-methylanilino) pyridine-2,3-dione S-
benzyl-3-isothiosemicarbazone 3a
Yellow solid; yield 58.7%; mp. 122e123 ꢂC; 1H NMR (CDCl3,
500 MHz) d: 2.18 (s, 3H, eCH3), 2.32 (s, 3H, eCH3), 4.29 (s, 2H, e
CH2e), 5.89 (brs, 2H, eNH2), 6.85 (d, J ¼ 7.5 Hz, 1H, AreH), 7.00e
7.14 (m, 3H, AreH), 7.22e7.30 (m, 9H, AreH), 7.43 (s, 1H, eNHe),
7.52 (s, 1H, pyridine-H), 7.94 (s, 1H, eNHe); 13C NMR (CDCl3,
4.4.6. (3Z, 20E)-5,6-di(p-fluoroanilino) pyridine-2,3-dione S-benzyl-
3-isothiosemicarbazone 3f
125 MHz) d: 17.82, 17.87, 33.98, 95.59, 119.66, 122.83, 124.94, 125.35,
Yellow solid; yield 78.9%; mp. 155e156 ꢂC; 1H NMR (CDCl3,
126.74, 127.34, 127.40, 128.58 (2C), 128.82 (2C), 129.20, 129.50,
131.17, 131.45, 131.48, 135.10, 137.27, 142.87, 143.85, 144.76, 160.81,
164.00; IR (KBr) v: 3269, 2921, 2851, 1687, 1584, 1506, 1348, 1393,
1332, 1302, 1145 cmꢁ1; MS (ESI, m/z): 483 (M þ H)þ. HRMS (ESI, m/
z) calcd for [C27H27N6OS]þ (M þ H)þ 483.1962, found 483.1972.
500 MHz) d: 4.49 (s, 2H, eCH2e), 5.98 (brs, 2H, eNH2), 6.94e7.05
(m, 3H, AreH), 7.13e7.18 (m, 4H, AreH), 7.24e7.33 (m, 5H, Are
H),7.41 (s, 1H, AreH), 7.43 (s, 1H, eNHe), 7.71 (s, 1H, pyridine-H),
8.22 (s, 1H, eNHe); 13C NMR (CDCl3, 125 MHz)
d: 34.01, 95.65,
116.19,119.70,122.33,123.77,123.84,127.43 (2C),127.57 (2C),128.62
(2C), 128.68 (2C), 131.48, 134.98, 137.33, 142.91, 143.73, 143.90,
144.21, 144.75, 164.10, 164.78; IR (KBr) v: 3302, 1690, 1639, 1587,
1518, 1469, 1359, 1385, 1319 cmꢁ1; MS (ESI, m/z): 491 (M þ H)þ.
HRMS (ESI, m/z) calcd for [C25H21F2N6OS]þ (M þ H)þ 491.1460,
found 491.1462.
4.4.2. (3Z, 20E)-5,6-di(m-methylanilino) pyridine-2,3-dione S-
benzyl-3-isothiosemicarbazone 3b
Yellow solid; yield 81.9%; mp. 143e144 ꢂC; 1H NMR (CDCl3,
500 MHz) d: 2.24 (s, 3H, eCH3), 2.38 (s, 3H, eCH3), 4.38 (s, 2H, e
CH2e), 5.94 (brs, 2H, eNH2), 6.75e6.82 (m, 3H, AreH), 7.01e7.13
(m, 4H, AreH), 7.25e7.34 (m, 6H, AreH), 7.61 (s, 2H, eNHe,
4.4.7. (3Z, 20E)-5,6-di(o-methoxyanilino) pyridine-2,3-dione S-
benzyl-3-isothiosemicarbazone 3g
pyridine-H), 8.04 (s,1H, eNHe); 13C NMR (CDCl3, 125 MHz)
d: 21.42,
Yellow solid; yield 62.5%; mp. 168e169 ꢂC; 1H NMR (CDCl3,
21.53, 34.16, 96.18, 117.67, 118.39, 121.21, 121.87, 124.76, 126.11,
127.53, 128.67, 128.97 (2C), 129.27 (2C), 130.00, 134.49, 137.10,
139.15, 139.44, 140.20, 143.33, 144.63, 145.40, 160.79, 164.28; IR
500 MHz) d: 3.82 (s, 3H, eOCH3), 3.86 (s, 3H, eOCH3), 4.39 (s, 2H, e
CH2e), 6.06 (brs, 2H, eNH2), 6.71 (t,1H, J ¼ 7.5 Hz, AreH), 6.88e7.01
(m, 5H, AreH), 7.15e7.38 (m, 6H, AreH), 7.50 (d, J ¼ 7.5 Hz, 1H, Are
H), 7.63 (s, 1H, eNHe), 7.92 (s, 1H, pyridine-H), 8.08 (s, 1H, eNHe);
(KBr) v: 3269, 2974, 2923, 1683, 1598, 1461, 1396, 1311, 1202 cmꢁ1
;
MS (ESI, m/z): 483 (M
þ
H)þ. HRMS (ESI, m/z) calcd for
[C27H27N6OS]þ (M þ H)þ 483.1962, found 483.1970.
13C NMR (CDCl3, 125 MHz)
d: 34.10, 34.12, 55.74, 96.33, 110.88,
112.17, 119.35, 120.62, 121.63, 122.82, 123.40, 126.24, 127.48, 128.67
(2C), 128.84, 128.92 (2C), 133.95, 134.04, 137.41, 143.75, 144.84,
149.59, 150.46, 160.89, 164.21; IR (KBr) v: 3283, 2936, 2838, 1692,
1646, 1591, 1532, 1466, 1331, 1323, 1246, 1120 cmꢁ1; MS (ESI, m/z):
515 (M þ H)þ. HRMS (ESI, m/z) calcd for [C27H27N6O3S]þ (M þ H)þ
515.1860, found 515.1868.
4.4.3. (3Z, 20E)-5,6-di(p-methylanilino) pyridine-2,3-dione S-
benzyl-3-isothiosemicarbazone 3c
Yellow solid; yield 83.2%; mp. 169e170 ꢂC; 1H NMR (CDCl3,
500 MHz) d: 2.24 (s, 3H, eCH3), 2.37 (s, 3H, eCH3), 4.36 (s, 2H, e
CH2e), 5.89 (brs, 2H, eNH2), 6.84 (d, J ¼ 8.0 Hz, 2H, AreH), 7.03 (d,
J ¼ 8.5, 2H, AreH), 7.17 (d, J ¼ 8.5, 2H, AreH), 7.22e7.35 (m, 7H, Are
H), 7.49 (s, 1H, eNHe), 7.55 (s, 1H, pyridine-H), 8.06 (s, 1H, eNHe);
4.5. Anticancer activity
13C NMR (CDCl3, 125 MHz)
d: 20.79, 20.89, 33.98, 95.56, 120.51 (2C),
121.68 (2C), 127.37, 128.54 (2C), 128.81 (2C), 129.88 (2C), 130.62
(2C), 133.71, 133.87, 133.94, 135.63, 136.33, 137.27, 143.28, 144.74,
160.70, 163.85; IR (KBr) v: 3296, 3227, 2921, 2855, 1702, 1581, 1519,
1506, 1470, 1348, 1326, 1308, 1238, 1102 cmꢁ1; MS (ESI, m/z): 483
(M þ H)þ. HRMS (ESI, m/z) calcd for [C27H27N6OS]þ (M þ H)þ
483.1962, found 483.1971.
The anticancer activities of the prepared compounds against
MCF-7, HCT-116 and BEL-7402 cells were evaluated as described
elsewhere with some modifications [25]. Target tumor cell lines
were grown to log phase in RPMI 1640 medium supplemented with
10% fetal bovine serum. Cells were harvested during logarithmic
growth phase and seeded in 96 well plates at a density of

W. Xie et al. / European Journal of Medicinal Chemistry 81 (2014) 22e27
27
2 ꢃ 104 cells/ml, and incubated at 37 ꢂC in a 5% CO2 incubator. After
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24 h incubation at 37 ꢂC, 10
ml tested compounds was added to 96-
well plates and cultured at 37 ꢂC for 72 h. 20
ml of MTT (5 mg/ml)
was added to each well and incubated for 4 h at 37 ꢂC. Discarded the
suspension and added 150 ml of dimethyl sulfoxide (DMSO) to each
well and shook the plates to dissolve the dark blue crystals (for-
mazan); the absorbance was measured using a microplate reader at
a wavelength of 570 nm. Each concentration was analyzed in
triplicate and the experiment was repeated three times. The
average 50% inhibitory concentration (IC50) was determined from
the doseeresponse curves according to the inhibition ratio for each
concentration. There was a good reproducibility between replicate
wells with standard errors below 10%. The results were summa-
rized in Table 1.
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We are grateful for the financial support from the Scientific
Research Fund of Hunan Provincial Education Department (No.
13A028) and Science and Technology Project of Hunan Province
(No. 2013SK3161). In carrying out this work, we thank Dr. Zhiliang
Xu for helping in doing biological assay.
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