Design, synthesis and biological evaluations of novel pyridone-thiazole hybrid molecules as antitumor agents

Article abstract of DOI:10.1016/j.ejmech.2017.12.038

A hybrid pharmacophore approach was adopted to design and synthesize new series of pyridone-thiazole hybrid compounds. The structures of the compounds were established by IR, ¹H NMR, ¹³C NMR, and HRMS. All the newly prepared compound

Full text of DOI:10.1016/j.ejmech.2017.12.038

Accepted Manuscript
Design, synthesis and biological evaluations of novel pyridone-thiazole hybrid
molecules as antitumor agents
Wenlin Xie, Yiqiang Wu, Jingai Zhang, Qihong Mei, Yahan Zhang, Ning Zhu, Renzhi
Liu, Huilin Zhang
PII:
S0223-5234(17)31050-4
10.1016/j.ejmech.2017.12.038
EJMECH 10016
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 23 September 2017
Revised Date: 11 November 2017
Accepted Date: 12 December 2017
Please cite this article as: W. Xie, Y. Wu, J. Zhang, Q. Mei, Y. Zhang, N. Zhu, R. Liu, H. Zhang, Design,
synthesis and biological evaluations of novel pyridone-thiazole hybrid molecules as antitumor agents,
European Journal of Medicinal Chemistry (2018), doi: 10.1016/j.ejmech.2017.12.038.
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ACCEPTED MANUSCRIPT
R
R
R
R
O
O
S
O
N
OH
OH
NH2
HN
HN
N
O
HN
HN
O
O
HN
HN
N
O
NH2NHCSNH2
NaIO3
S
N
NH2
Cl
ethanol
N
+
2
R
H
H
N
H2SO4
N
N
N
R
R
3b R= o-Cl, IC50 (µM) = 3.15 (MGC803)
IC50 (µM) = 8.17 (HCT116)

ACCEPTED MANUSCRIPT
Design, synthesis and biological evaluations of novel pyridone-
thiazole hybrid molecules as antitumor agents
Wenlin Xiea,b,c*, Yiqiang Wua, Jingai Zhanga, Qihong Meia, Yahan Zhang a, Ning Zhua, Renzhi Liua,
Huilin Zhanga
aSchool of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China
bKey Laboratory of Theoretical Organic Chemistry and Function Molecule of Ministry of Education, Hunan University of
Science and Technology, Xiangtan 411201, China
cHunan Provincal Key Laboratory of Controllable Preparation and Functional Application of Fine Polymers, Xiangtan
411201, China
Abstract: A hybrid pharmacophore approach was adopted to design and synthesize new series of
1
pyridone-thiazole hybrid compounds. The structures of the compounds were established by IR, H NMR,
13C NMR, and HRMS. All the newly prepared compounds (3a-3m) were in vitro evaluated for their
antiproliferative activity against three human cancer cell lines, namely Colon cancer (HCT-116), gastric
carcinoma (MGC803) and hepatocellular cancer (Huh7). Bioassay results demonstrated that most of the
tested compounds showed potent anti-tumor activities against various cancer cells in vitro, and some
compounds exhibited stronger effects than positive control 5-Fluorouracil (5-FU). Compound 3b showed
the best anti-tumor activity with IC50 values of 8.17 µM and 3.15 µM against HCT116 and MGC803 cell
lines, respectively, which was 1.4-8.1 times more potent than 5-Fluorouracil (IC50 = 11.29 µM and 25.54
µM against HCT116 and MGC803 respectively). These findings suggest that compound 3b may have
potential to be developed as a promising lead for the design of novel anticancer small-molecule drugs.
Keywords: Pyridone Thiazole Hybrids Synthesis Antitumor activity
1. Introduction
Molecular hybridization is a valuable structural modification approach that comprises the incorporation of
two or more pharmacophores into a single entity. In the last few years, hybrid drug design has emerged as
a prime tool for the discovery of innovative anticancer therapies that can potentially overcome most of the
pharmacokinetic drawbacks encountered when using conventional anticancer drugs.
The pyridin-2(1H)-one ring system present in various natural active substances [1,2]. The existence of a
pyridin-2(1H)-one structural unit is a key to the pharmacological activities of many natural and synthetic
*Corresponding authors. Wenlin Xie: Tel./fax: +86 0731 58290045.
E-mail address: xwl2000zsu@163.com (W. L. Xie)

ACCEPTED MANUSCRIPT
drugs. A large number of compounds having pyridin-2(1H)-one ring system has been reported to possess
different kind of biological activities like anti-tumor [3], cardiotonic [4], antituberculosis [5], antibacterial
[6] and antihepatitis B virus [7]. Recently, pyridin-2(1H)-ones include 5-ethyl-1-phenyl-2-(1H)-pyridone
[8], Camptothecin [9] and 3-(4,5,6,7-tetrahydro-3H-imidazo[4,5-c]pyridin-2-yl)-1H-quinolin-2-one [10]
have been reported to show strong cytotoxicity against several human cancer cell lines.
Heterocycles containing the thiazole moiety are important targets in synthetic and medicinal chemistry
because this fragment is a key moiety in a number of natural and synthetic biologically active agents
[11,12]. In the last few decades, the clinical efficacy of tiazofurin and its analogs, and bleomycins (BLMs)
has pointed out the importance of thiazole moiety for anticancer drug design. Bleomycins, glycopeptide
antitumor antibiotics produced and isolated from Streptomyces sp have been clinically used to treat several
types of cancers, like squamous cell carcinomas, malignant lymphomas and testicular cancers. In view of
these reports and in continuation with the previous work, we therefore envisaged that integrating
pyridin-2(1H)-one and thiazole moieties in one molecular platform could potentially produce novel
compounds with significant synergistic antitumor properties (Fig. 1). These new pyridin-2(1H)-ones
analogues bearing thiazole moiety (3a-3m) were prepared to verify their efficacy as potential anticancer
agents.
2

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Cl
O
N
O
MeO
O
N
H
N
O
O
Cl
S
R
N
O
N
O
N
O
H
N
Me
Pyridone L-697
N
Me
N
SMART
N
N
F
N
O
H
NH
N
F
N
Me
AMG 337
HN
Me
N
N
N
H
N
N
S
N
N
N
H
O
Cl
N
HO
Cl
Dasatinib, BMS-354825
BMS-695735
Structures of some important thiazole derivatives
Structures of some important pyridone derivatives
Molecular
Hybridization
R
O
N
HN
N
O
S
N
H
HN
R
N
pyridone-thiazole hybrid molecules
Fig. 1. Design of pyridone-thiazole hybrid compounds
2. Results and discussion
2.1. Chemistry
The synthetic pathways employed to prepare the new targeted derivatives are depicted in Scheme 1. The
key intermediate 2 was prepared according to the procedure described in the literature [13]. First,
2,3-dihydroxypyridine was treated with appropriate aromatic amine in the presence of oxidant NaIO3 in
one pot via oxidation-Michael additions to yield 5,6-disubstituted pyridine-2,3-diones 1, in the next step,
5,6-disubstituted pyridine-2,3-diones 1 was reacted with thiosemicarbazide through refluxing in anhydrous
EtOH to afford the desired intermediate 2. Subsequently, the intermediate 2 was reacted with
3

ACCEPTED MANUSCRIPT
3-chloro-2,4-pentanedione via substitution-condensation reaction in refluxing ethanol to obtain the
corresponding target compound 3a-3m with good yields. The structures of all new synthesized compounds
1
3a-3m were confirmed by H NMR, 13C NMR, IR and HRMS. IR spectra of the compounds 3 showed
absorption bands due to the NH groups in the region 3140-3447 cm-1, in addition to a carbonyl band in the
1
region 1602-1657 cm-1. In the H NMR spectrum of 3a, six singlet was observed (δ = 13.48, 7.98, 7.80,
6.68, 2.60, 2.47 ppm) for three NH group, pyridone-H, O=C-CH3 and CH3 respectively. The 13C NMR
spectrum of 3a showed characteristic signals at δ 30.14 ppm (generated by the CH3 of the acetyl group),
18.63 ppm (due to the CH3 of thiazole ), and 189.83, 167.85 ppm (arising from two carbonyl groups).
2.2. Biological activity
The in vitro antitumor activity of the newly synthesized compounds 3a-3m was evaluated against a panel
of three human cancer cell lines, including HCT116 (colon carcinoma cell), MGC803 (gastric carcinoma
cell) and Huh7 (hepatoma carcinoma cell) by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide) method. 5-Fluorouracil was used as positive control, and the results expressed as half-maximal
inhibitory concentration (IC50) values and are presented in Table 1, as mean values of experiments
performed in triplicate. From the screening results in Table 1, it was observed that most of the synthesized
compounds exhibited potent cytotoxic activities against the three human cancer cell lines. Special
compounds 3a, 3b and 3c displayed higher cytotoxicity activity than 5-FU against HCT116 and MGC803
cell lines. The IC50 values of the most promising compound 3b were 3.15 μM, and 8.17 μM against
MGC803 and HCT116 cell lines, respectively, these values indicated that this compound was 8.1 and 1.4
times more active than 5-FU (IC50 values: 25.54 μM and 11.29 μM, respectively). Although most
compounds showed potent antitumor activity, some compounds exhibited selectivity between the three
human cancer cell lines. Such as compounds 3a, 3c and 3j showed the more potent inhibitory activity
against HCT116 and MGC803 cell line and less inhibitory activity against Huh7 cell line.
From the antitumor activity against three human cancer cell lines, preliminary structure-activity
relationships of the synthesized compounds were achieved. In general, compared with compounds 3a-3m,
substituent on benzene ring had great effect on the cytotoxic activity. Introduction of electron-withdrawing
groups (such as Cl, Br and F) on the phenyl ring improved the activity. For example, the compound 3a, 3b,
3c, 3j, 3k and 3l displayed the more potent antitumor activity than the compound (3m) with no substituent
on the phenyl ring against MGC803 and HCT116 cell lines. However, introduction of electron-donating
4

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group (such as methyl and methoxyl group) on the phenyl ring reduced the inhibitory activity. For
example, the compounds 3d, 3e, 3f, 3g, 3h and 3i displayed the lower antitumor activity than the
compound (3m) against the three human cancer cell lines. These data also suggested that compound 3b is
a promising antitumor agent.
R
R
S
OH
OH
NH2
HN
HN
O
O
HN
HN
N
O
b
N
NH2
a
+
2 R
H
N
N
N
R
R
1
2
R
O
O
O
N
HN
HN
N
O
S
Cl
N
H
c
N
R
3
Scheme 1. Synthesis of the pyridone-thiazole hybrids derivatives (3). Reagent and conditions: (a) NaIO3,
rt; (b) NH2NHCSNH2, EtOH, H2SO4, reflux; (c) EtOH, heat to reflux
Table 1 In vitro antiproliferative activity of 3-(2-(4-acetyl-5-methylthiazol-2-yl)hydrazono)-
5,6-disubstituted pyridin-2(1H)-one (3)
IC50a (µM)
Compound
R
HCT-116
10.59±1.49
8.17±1.89
8.28±2.44
52.66±9.73
＞128
MGC803b
5.18±1.62
3.15±1.68
8.56±0.64
75.45±1.69
45.02±2.09
＞128
Huh7b
3a
3b
3c
3d
3e
3f
m-Cl
＞128
o-Cl
21.47±1.97
＞128
p-Cl
p-CH3
o-CH3
m-CH3
p-CH3O
o-CH3O
m-CH3O
m-Br
72.01±2.95
＞128
＞128
＞128
3g
3h
3i
＞128
82.64±1.77
51.05±1.28
＞128
＞128
85.40±1.47
＞128
20.62±2.43
＞128
3j
22.17±1.28
13.21±1.26
21.56±1.33
9.12±1.45
＞128
3k
p-Br
17.87±1.86
5

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3l
m-F
H
22.84±1.18
21.39±1.39
58.84±2.18
3m
25.34±5.93
11.29±1.06
13.54±1.16
25.54±0.05
19.05±1.69
5.63±0.14
5-FU
a
IC50 is the concentration of compound required to inhibit the cell growth by 50% compared to an untreated control. Each
value represents the mean ± S.E. of three experiments.
b HCT116 cells were the human colon carcinoma cells, MGC80 cells were the human gastric carcinoma cell and Huh7 cells
were the human hepatocellular carcinoma cell.
3. Conclusions
In summary, in order to develop potent antitumor agents, we have designed and synthesized a series of
novel hybrid molecules containing pyridone bearing thiazole moiety, and evaluated their in vitro antitumor
activities against HCT116, MGC803 and Huh7 human tumor cell lines by MTT assay. Some of the
compounds inhibited the proliferation better than positive control 5-Fluorouracil. In particular, compound
3b showed the best inhibitory effect against MGC803 snd HCT116 cells, with IC50 value of 3.15±1.68 µM
and 8.17±1.89 µM, respectively. Therefore, the results laid a foundation for further improving the potency
and the selectivity of this series of compounds.
4. Experimental
4.1. General
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 cm-1. 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
1
was used as an internal reference for H and 13C chemical shifts and CDCl3 was 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 purchased from Aladdin-Reagent and
Sinopharm Chemical Reagent, and were used without further purification.
4.2. Synthesis of 5,6-disubstituted pyridine-2,3-dione-3- thiosemicarbazone derivatives (2)
According to the literature method [13,14], sodium iodate (1.38g, 7.0 mmol) was added to a solution of
2,3-dihydroxypyridine (0.70g, 6.3 mmol) in 0.5 mol/L phosphate-buffered saline (35.0 mL, pH 6.0) and
125mL 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, 150mL water was added, and the precipitate formed was isolated by
6

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filtration. The resulting crude product was purified by column chromatography on silica gel to afford the
corresponding 1.
To a solution of 5,6-disubstituted pyridine-2,3-diones 1 (4 mmol) in anhydrous ethanol (60 mL) were
added thiosemicarbazide (4.2 mmol) and sulfuric acid (0.04 mmol). The reaction mixture was refluxed and
the reaction monitored by TLC，after the completion of the reaction, 200mL 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. General procedure for the synthesis of 3-(2-(4-acetyl-5-methylthiazol-2-yl)hydrazono)-
5,6-disubstituted pyridin-2(1H)-ones (3)
Compound 2 (1 mmol) and 3-chloro-2,4-pentanedione (0.148 g, 1.1 mmol) were added to absolute ethanol
(15 mL). The reaction mixture was heated at reflux for 12 h. After removal of solvent under reduced
pressure, the residue was purified by silica gel chromatography using hexanes–ethyl acetate (7:3) to
provide the desired compounds 3.
4.3.1 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(3-chlorophenylamino)
pyridin-2(1H)-one 3a
1
Red solid; yield 71.8%; mp. 235-236 ; H NMR (500 MHz, CDCl3) δ: 13.48 (s, 1H, NH), 7.98 (s, 1H,
NH), 7.80 (s, 1H, NH), 7.53-7.46 (m, 3H, PhH), 7.37-7.31 (m, 2H, PhH), 7.15 (t, J = 7.5 Hz, 1H, PhH),
7.07 (t, J = 8.0 Hz, 1H, PhH), 6.98 (d, J = 7.5 Hz, 1H, PhH), 6.68 (s, 1H, pyridone-H), 2.60 (s, 3H, CH3),
2.47 (s, 3H, CH3); 13C NMR (125 MHz, CDCl3) δ: 189.83, 167.85, 158.86, 157.61, 142.28, 142.26, 136.31,
132.01, 130.86, 130.36, 130.27, 128.27, 127.76, 126.46, 126.19, 125.82, 125.69, 124.3, 121.91, 121.30,
104.64, 30.14, 18.63; IR(KBr) ν: 3424, 3287, 3020, 2981, 1649, 1623, 1587, 1522, 1403, 1364, 1316,
1242, 1139, 1052 cm-1; HRMS (ESI, m/z) calcd for [C23H19Cl2N6O2S]+ (M+H)+ 513.0662, found
513.0668.
4.3.2 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(2-chlorophenylamino)
pyridin-2(1H)-one 3b
Red powder; yield 67.0%; mp. 136-137 ; 1H NMR (500 MHz, CDCl3) δ: 13.49 (s, 1H, NH), 7.95 (s, 1H,
NH), 7.80 (s, 1H, NH), 7.54-7.46 (m, 3H, PhH), 7.38-7.31 (m, 2H, PhH), 7.16 (t, J = 7.5 Hz, 1H, PhH),
7.07 (t, 1H, J = 7.5 Hz, PhH), 6.98 (d, J = 8.0, Hz, 1H, PhH), 6.69 (s, 1H, pyridone-H), 2.61 (s, 3H, CH3),
2.48 (s, 3H, CH3); 13C NMR (125 MHz, CDCl3) δ: 189.79, 167.84, 158.83, 157.36, 142.27, 142.24,
7

ACCEPTED MANUSCRIPT
136.30, 132.07, 130.86, 130.36(2C), 128.27, 127.76, 126.46, 126.22, 125.82, 125.67, 124.34, 121.91,
121.33, 104.60, 30.12, 18.57; IR(KBr) ν: 3427, 3215, 3012, 2973, 1622, 1609, 1525, 1320, 1243, 1138,
1052 cm-1; HRMS (ESI, m/z) calcd for [C23H19Cl2N6O2S]+ (M+H)+ 513.0662, found 513.0659.
4.3.3 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(4-chlorophenylamino)
pyridin-2(1H)-one 3c
1
Black powder; yield 55.0%; mp. 147-148 ; H NMR (500 MHz, CDCl3) δ: 13.45 (s, 1H, NH), 8.11 (s,
1H, NH), 7.41-7.36 (m, 4H, PhH), 7.33 (s, 1H, NH), 7.19 (d, J = 6.5 Hz, 2H, PhH), 6.88 (d, J = 7.0 Hz, 2H,
13
PhH), 6.60 (s, 1H, pyridone-H), 2.60 (s, 3H, CH3), 2.47 (s, 3H, CH3); C NMR (125 MHz, CDCl3) δ:
189.81, 167.85, 158.86, 157.67, 143.57, 142.01, 137.80, 132.68, 131.07, 130.42, 130.40, 129.80, 129.15,
125.51, 122.71, 122.10, 103.86, 29.71, 18.59; IR(KBr) ν: 3238, 3142, 3010. 2924, 1635, 1616, 1497, 1401,
1364, 1315, 1235, 1128, 970, 819, 637cm-1; HRMS (ESI, m/z) calcd for [C23H19Cl2N6O2S]+ (M+H)+
513.0662, found 513.0663.
4.3.4 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(4-methylphenylamino)
pyridin-2(1H)-one 3d
1
Red solid; yield 62.0%; mp. 177-178 ; H NMR (500 MHz, CDCl3) δ: 13.44 (s, 1H, NH), 8.17 (s, 1H,
NH), 7.33 (s, 1H, NH), 7.21 (t, J = 7.5 Hz,4H, PhH), 7.14 (d, J = 8.0 Hz, 2H, PhH), 6.82 (d, J = 8.0 Hz,
13
2H, PhH), 6.54 (s, 1H, pyridone-H), 2.59 (s, 3H, CH3), 2.45 (s, 3H, CH3), 2.36 (s, 6H, CH3); C NMR
(125 MHz, CDCl3) δ: 189.80, 168.17, 159.17, 157.80, 142.57, 141.65, 136.55, 135.15, 133.94, 133.82,
131.13, 130.79, 130.20, 125.01, 121.99, 120.51, 102.28, 30.15, 29.71, 20.94, 18.63; IR(KBr) ν: 3435,
3151, 3012, 2923, 1643, 1605, 1519, 1399, 1364, 1316, 1241, 1134 cm-1; HRMS (ESI, m/z) calcd for
[C25H25N6O2S]+ (M+H)+ 473.1754, found 473.1756.
4.3.5 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(2-methylphenylamino)
pyridin-2(1H)-one 3e
Purple powder; yield 68.0%; mp. 147-148 ℃; 1H NMR (500 MHz, CDCl3) δ: 13.45 (s, 1H, NH), 8.01 (s,
1H, NH), 7.38 (s, 1H, NH), 7.32-7.25 (m, 5H, PhH), 7.16-7.12 (m, 2H, PhH), 6.83 (d, J = 7.5 Hz, 1H,
PhH), 6.32 (s, 1H, pyridone-H), 2.60 (s, 3H, CH3), 2.45 (s, 3H, CH3), 2.32 (s, 3H, CH3), 2.18 (s, 3H,
CH3); 13C NMR (125 MHz, CDCl3) δ: 189.77, 168.11, 159.22, 157.74, 143.69, 141.20, 137.43, 134.01,
131.90, 131.60, 131.35, 131.11, 129.61, 127.45, 127.10, 125.56, 125.19, 125.03, 123.34, 119.52, 102.31,
8

ACCEPTED MANUSCRIPT
30.14, 18.59, 17.82, 17.81; IR(KBr) ν: 3445, 3310, 3020, 2931, 1657, 1627, 1519, 1459, 1401, 1363, 1326,
1221, 1123, 752cm-1; HRMS (ESI, m/z) calcd for [C25H25N6O2S]+ (M+H)+ 473.1754, found 473.1758.
4.3.6 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(3-methylphenylamino)
pyridin-2(1H)-one 3f
Red powder; yield 64.2%; mp. 242-243 ; 1H NMR (500 MHz, CDCl3) δ: 13.48 (s, 1H, NH), 8.07 (s, 1H,
NH), 7.37 (s, 1H, NH), 7.33-7.29 (m, 2H, PhH), 7.09-7.02 (m, 3H, PhH), 6.96 (d, J = 7.5 Hz, 1H, PhH),
6.74-6.72 (m, 2H, PhH), 6.64 (s, 1H, pyridone-H), 2.61 (s, 3H, CH3), 2.47 (s, 3H, CH3), 2.40 (s, 3H,
CH3), 2.38 (s, 3H, CH3); 13C NMR (125 MHz, CDCl3) δ: 189.83, 168.12, 159.13, 157.75, 145.19, 141.61,
140.38, 139.69, 139.20, 133.31, 131.00, 130.11, 129.46, 126.28, 125.20, 124.92, 122.26, 121.09, 118.51,
117.51, 102.94, 30.16, 21.56, 21.49, 18.64; IR(KBr) ν: 3363, 3165, 3018, 2923, 1647, 1612, 1530, 1401,
1365, 1328, 1130, 930, 640cm-1; HRMS (ESI, m/z) calcd for [C25H25N6O2S]+ (M+H)+ 473.1754, found
473.1757.
4.3.7 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(4-methoxyphenylamino)
pyridin-2(1H)-one 3g
1
Purple powder; yield 69.7%; mp. 202-203 ; H NMR (500 MHz, CDCl3) δ: 13.44 (s, 1H, NH), 8.17 (s,
1H, NH), 7.21-7.19 (m, 3H, NH, PhH), 6.98-6.95 (m, 4H, PhH), 6.89 (d, J = 8.5 Hz, 2H, PhH), 6.38 (s, 1H,
13
pyridone-H), 3.84 (s, 3H, CH3), 3.83 (s, 3H, CH3), 2.60 (s, 3H, CH3), 2.45 (s, 3H, CH3); C NMR (125
MHz, CDCl3) δ: 189.78, 168.19, 159.22, 157.82, 157.36, 156.81, 141.57, 138.02, 134.84, 131.91, 131.24,
124.94, 124.53, 121.88, 115.54, 114.91, 101.58, 55.60, 55.57, 30.14, 18.62; IR(KBr) ν: 3361, 3198, 3013,
2925, 1638, 1602, 1512, 1399, 1364, 1290, 1241, 1137, 1031, 918, 777, 643cm-1; HRMS (ESI, m/z) calcd
for [C25H25N6O4S]+ (M+H)+ 505.1653, found 505.1658.
4.3.8 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(2-methoxyphenylamino)
pyridin-2(1H)-one 3h
1
Purple powder; yield 62.0%; mp. 179-180 ; H NMR (500 MHz, CDCl3) δ: 13.49 (s, 1H, NH), 8.14 (s,
1H, NH), 7.39 (s, 1H, NH), 7.35-7.29 (m, 2H, PhH), 6.85 (d, J = 8.0 Hz, 1H, PhH), 6.79-6.75 (m, 2H,
PhH), 6.70-6.67 (m, 2H, PhH), 6.50 (d, J = 8.0 Hz, 1H, PhH), 6.48 (s, 1H, pyridone-H), 3.84 (s, 3H, CH3),
3.83 (s, 3H, CH3), 2.61 (s, 3H, CH3), 2.47 (s, 3H, CH3); 13C NMR (125 MHz, CDCl3) δ: 189.84, 168.09,
161.19, 160.72, 159.03, 157.72, 146.48, 141.83, 140.51, 132.88, 131.16, 130.80, 130.42, 125.22, 113.68,
112.52, 111.02, 109.09, 107.44, 106.56, 103.76, 55.43, 55.41, 30.15, 18.58; IR(KBr) ν: 3322, 3195, 3015,
2925, 1654, 1621, 1528, 1401, 1364, 1238, 1140 cm-1; HRMS (ESI, m/z) calcd for [C25H25N6O4S]+
(M+H)+ 505.1653, found 505.1656.
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4.3.9 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(3-methoxyphenylamino)
pyridin-2(1H)-one 3i
Red powder; yield 72.0%; mp. 164-165 ℃; 1H NMR (500 MHz, CDCl3) δ: 13.49 (s, 1H, NH), 8.13 (s, 1H,
NH), 7.39 (s, 1H, NH), 7.36-7.30 (m, 2H, PhH), 6.87-6.75 (m, 4H, PhH), 6.70 (s, 1H, PhH), 6.50 (d, J =
8.0 Hz, 1H, PhH), 6.48 (s, 1H, pyridone-H), 3.85 (s, 3H, CH3), 3.83 (s, 3H, CH3), 2.61 (s, 3H, CH3), 2.47
(s, 3H, CH3); 13C NMR (125 MHz, CDCl3) δ: 189.85, 168.07, 161.18, 160.71, 159.04, 157.75, 146.49,
141.83, 140.51, 132.88, 131.15, 130.79, 130.42, 125.23, 113.67, 112.54, 111.01, 109.08, 107.43, 106.57,
103.76, 55.43, 55.41, 30.14, 18.59; IR(KBr) ν: 3435, 3171, 3011, 2935, 1652, 1618, 1528, 1400, 1319,
1263, 1136, 1043, 694, 642cm-1; HRMS (ESI, m/z) calcd for [C25H25N6O4S]+ (M+H)+ 505.1653, found
505.1651.
4.3.10 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(3-bromophenylamino)
pyridin-2(1H)-one 3j
Red solid; yield 58.2%; mp. 136-137 ℃; 1H NMR (500 MHz, CDCl3) δ: 13.49 (s, 1H, NH), 8.11 (s, 1H,
NH), 7.39 (s, 1H, NH), 7.36-7.28 (m, 5H, PhH), 7.19 (d, J = 6.5 Hz, 1H, PhH), 7.11 (s, 1H, PhH), 6.86 (d,
J = 7.5 Hz, 1H, PhH), 6.67 (s, 1H, pyridone-H), 2.61 (s, 3H, CH3), 2.48 (s, 3H, CH3); 13C NMR (125 MHz,
CDCl3) δ: 189.86, 167.81, 158.86, 157.61, 146.54, 142.15, 140.71, 132.14, 131.55, 130.95, 130.12, 128.52,
126.89, 125.62, 124.06, 123.92, 123.82, 123.31, 119.59, 119.33, 104.68, 30.16, 18.56; IR(KBr) ν: 3433,
3140, 3010, 2931,1634, 1615, 1586, 1522, 1400, 1366, 1319, 1238, 1138, 776, 637cm-1; HRMS (ESI, m/z)
calcd for [C23H19Br2N6O2S]+ (M+H)+ 600.9651, found 600.9656.
4.3.11 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(4-bromophenylamino)
pyridin-2(1H)-one 3k
1
Red solid; yield 51.0%; mp. 154-155 ℃; H NMR (500 MHz, CDCl3) δ: 13.51 (s, 1H, NH), 8.03 (s, 1H,
NH), 7.58-7.52 (m, 4H, PhH), 7.32 (s, 1H, NH), 7.14 (d, J = 8.0 Hz, 2H, PhH), 6.82 (d, J = 7.5 Hz, 2H,
PhH), 6.63 (s, 1H, pyridone-H), 2.62 (s, 3H, CH3), 2.48 (s, 3H, CH3); 13C NMR (125 MHz, CDCl3) δ:
189.95, 167.99, 158.99, 157.81, 143.71, 142.15, 137.93, 132.81, 131.21, 130.56, 130.40, 129.93, 129.29,
125.65, 122.85, 122.23, 103.99, 30.29, 18.72; IR (KBr ) ν: 3447, 3168, 3012, 2929, 1634, 1609, 1524,
1340, 1325, 1260, 1129 cm-1; HRMS (ESI, m/z) calcd for [C23H19Br2N6O2S]+ (M+H)+ 600.9651, found.
600.9652.
4.3.12 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(3-fluorophenylamino)
pyridin-2(1H)-one 3l
1
Black powder; yield 65.5%; mp. 153-153 ℃; H NMR (500 MHz, CDCl3) δ: 13.50 (s, 1H, NH), 8.05 (s,
1H, NH), 7.44-7.40 (m, 2H, NH, PhH), 7.36 (t, J = 7.5 Hz, 1H, PhH), 7.03-6.98 (m, 2H, PhH), 6.94 (t, J =
8.0 Hz, 1H, PhH), 6.83 (t, J = 8.0 Hz, 1H, PhH), 6.74 (s, 1H, PhH), 6.72-6.67 (m, 2H, PhH, pyridone-H),
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2.62 (s, 3H, CH3), 2.48 (s, 3H, CH3); 13C NMR (125 MHz, CDCl3) δ: 189.82, 167.79, 163.85 (d, J =
248.75 Hz), 163.52 (d, J = 245.00 Hz), 158.82, 157.68, 146.80 (d, J = 8.8 Hz), 142.09, 140.98 (d, J = 10.0
Hz), 132.05, 131.70 (d, J = 8.8 Hz), 130.94 (d, J = 8.8 Hz), 130.12, 125.54, 116.52 (d, J = 3.8 Hz), 116.20
(d, J = 2.5 Hz), 112.45 (d, J = 21.3 Hz), 110.58 (d, J = 21.3 Hz), 108.48 (d, J = 22.5 Hz ), 107.97 (d, J =
25.0 Hz), 104.79, 30.17, 18.57; IR(KBr) ν: 3446, 3158, 3015, 2926, 1638, 1609, 1499, 1401, 1363, 1316,
1228, 1115 cm-1; HRMS (ESI, m/z) calcd for [C23H19F2N6O2S]+ (M+H)+ 481.1253, found 481.1251.
4.3.13 (Z)-3-(2-(4-Acetyl-5-methylthiazol-2-yl)hydrazono)-5,6-bis(phenylamino)pyridin-2(1H)-one 3m
Brown powder; yield 56.2%; mp. 237-238 ; 1H NMR (500 MHz, CDCl3) δ: 13.47 (s, 1H, NH), 8.10 (s,
1H, NH), 7.46-7.40 (m, 5H, NH, PhH), 7.27 (d, J = 5.5 Hz, 2H, PhH), 7.22 (t, J = 7.5 Hz, 1H, PhH), 7.15
(t, J = 7.0 Hz, 1H, PhH), 6.94 (d, J = 7.5 Hz, 2H, PhH), 6.67 (s, 1H, pyridone-H), 2.61 (s, 3H, CH3), 2.47
(s, 3H, CH3); 13C NMR (125 MHz, CDCl3) δ: 189.80, 168.08, 159.08, 157.74, 145.20, 141.69, 139.28,
133.15, 130.85, 130.28, 129.69, 125.49, 125.22, 124.01, 121.47, 120.63, 103.13, 30.14, 18.61; IR(KBr) ν:
3442, 3167, 3020, 2925, 1632, 1612, 1494, 1401, 1313, 1233, 1110 cm-1; HRMS (ESI, m/z) calcd for
[C23H21N6O2S]+ (M+H)+ 445.1441, found 445.1443.
4.4. Anti-proliferative assay
The anticancer activities of the prepared compounds against HCT-116, MGC803 and Huh7 cells were
evaluated as described elsewhere with some modifications [15]. 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 2×104 cells/mL, and incubated at
37 in a 5% CO2 incubator. After 24 h incubation at 37 , 10 μl tested compounds was added to 96-well
plates and cultured at 37 for 72 h, 20 μl of MTT (5 mg/mL) was added to each well and incubated for 4
h at 37 . Discarded the suspension and added 150 mL of dimethyl sulfoxide (DMSO) to each well and
shook the plates to dissolve the dark blue crystals (formazan); 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 dose-response 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 summarized in
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Table 1.
Acknowledgments
The authors thank the National Natural Science Foundation of China (No. 21571058), the Natural Science
Foundation of Hunan Province (2015JJ4026), and the Scientific Research Fund of Hunan Provincial
Education Department (No. 17K032) for the financial support of this work.
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►
►
We explored synthetic methods of novel pyridone-thiazole hybrid molecules
All newly synthesized compounds were screened for their anticancer activities.
► Most of the prepared compounds exhibited cytotoxicity against various cancer cells in
vitro. (3b: IC50 (µM) = 3.15 (MGC803); 8.17 (HCT116))
►
The structure-activity relationship was discussed.