Synthesis, characterization and cytotoxicity of the gold(III) complexes of 4,5-dihydropyrazole-1-carbothioamide derivatives

Article abstract of DOI:10.1016/j.ejmech.2011.02.031

Eight new gold(III) complexes (1-8) of 5-aryl-3-(pyridin-2-yl)-4,5- dihydropyrazole-1-carbothioamide have been synthesized and characterized by elemental analysis, molar conductivity, IR, UV, ¹H NMR, ¹³C NMR, MS, and thermal analysis

Full text of DOI:10.1016/j.ejmech.2011.02.031

European Journal of Medicinal Chemistry 46 (2011) 1914e1918
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis, characterization and cytotoxicity of the gold(III) complexes
of 4,5-dihydropyrazole-1-carbothioamide derivatives
,
a
a
a
b
a,
Shuxiang Wang a , Wenqing Shao , Hongdong Li , Cui Liu , Ke Wang , Jinchao Zhang
*
*
a Chemical Biology Key Laboratory of Hebei Province, College of Chemistry and Environmental Science, Hebei University, Baoding 071002, Hebei, PR China
b Shijiazhuang Center for Disease Control and Prevention, Shijiazhuang 050011, Hebei, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Eight new gold(III) complexes (1e8) of 5-aryl-3-(pyridin-2-yl)-4,5-dihydropyrazole-1-carbothioamide
have been synthesized and characterized by elemental analysis, molar conductivity, IR, UV, 1H NMR, 13
C
Received 8 November 2010
Received in revised form
6 February 2011
Accepted 13 February 2011
Available online 22 February 2011
NMR, MS, and thermal analysis techniques. The cytotoxicity was tested by MTT assay. The results indicate
that the complexes 1e8 exert cytotoxic effects against HeLa and A549 cell lines. Moreover, the complexes
1, 4, 5, 7 and 8 have higher cytotoxicity than cisplatin against HeLa cell line. It suggests that the
substituent groups on benzene have important effect on cytotoxicity.
Crown Copyright Ó 2011 Published by Elsevier Masson SAS. All rights reserved.
Keywords:
Gold(III) complex
Dihydropyrazole derivative
Cytotoxicity
1. Introduction
complexes, such as the preference for square-planar coordination
and the typical d8 electronic configuration. Surprisingly, despite
The landmark discovery of cisplatin by Rosenberg in 1965 her-
alded a new area of anticancer drug research based on metal-
lopharmaceuticals [1]. To date, cisplatin and its analogues are some
of the most effective chemotherapeutic agents in clinical use as the
first line of treatment in testicular and ovarian cancers. Unfortu-
nately, they have several major drawbacks. Common problems
include cumulative toxicities of nephrotoxicity and ototoxicity
[2e5]. In addition to the serious side effects, the therapeutic effi-
cacy is also limited by inherent or treatment-induced resistant
tumor cells. These drawbacks have provided the motivation for
alternative chemotherapeutic strategies.
Metals, in particularly, transition metals offer potential advan-
tages over the more common organic-based drugs. For example,
a wide range of coordination numbers and geometries, accessible
redox states, ‘tune-ability’ of the thermodynamics and kinetics of
ligand substitution. Gold(III) complexes show chemical features
that are very close to those of clinically employed platinum(II)
this strict similarity, little literature data exist on the use of gold(III)
complexes as anticancer drugs. The paucity of data on gold(III)
complexes probably derives from their high redox potential and
relatively poor stability, which make their use rather problematic
under physiological conditions. In recent years, gold(III) complexes
with polyamines, polypyridines [6], porphyrins [7,8] and dithio-
carbamate [9e11], have been synthesized and characterized, and
showed sufficient stability under physiologically relevant condi-
tions by introducing chelating ligands. Intriguingly, some of these
gold(III) compounds displayed in vitro cytotoxicity comparable to or
even greater than cisplatin toward a series of established human
tumor cell lines, and only a minimal cross-resistance with the
reference drug was observed. The ligands generally coordinated to
metal ions by nitrogen or sulfur atom in these stable complexes.
Guo et al. reported the cytotoxicity of three gold complexes [Au
(Quinpy)Cl]Cl, [Au(Quingly)Cl]Cl and [Au(Quinala)Cl]Cl with three
AueN bonds. The cytotoxicity of [Au(Quinpy)Cl]Cl against A549
cells is about 3 times higher than that of cisplatin. [Au(Quinala)Cl]Cl
is active against B16-BL6 with an inhibition rate of 67.52% at
a concentration of 10ꢀ7 $ mol Lꢀ1 [12]. Ronconi et al. synthesized
a series of gold(III) complexes with AueS bonds, most of them are
much more cytotoxic in vitro than cisplatin [9]. In our present work,
a series of gold(III) complexes with one AueS and two AueN bonds
were synthesized, all of them have cytotoxicity against HeLa cell
line, especially the complexes 1, 4, 5, 7 and 8 show higher cyto-
toxicity than cisplatin.
Abbreviations: HQuinpy, N-(8-quinolyl)pyridine-2-carboxamide; HQuingly,
N-(8-quinolyl)glycine-carboxamide; HQuinala, N-(8-quinolyl)-l-alanine-carbox-
amide; py, pyridine dhpy dihydropyrazole; DMSO, dimethyl sulfoxide; MTT, 3-(4,5-
dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; OD, optical density; SD,
standard deviation.
* Corresponding authors. Tel./fax: þ86 0312 5079361.
E-mail addresses: wsx@hbu.edu.cn (S. Wang), jczhang6970@yahoo.com.cn
(J. Zhang).
0223-5234/$ e see front matter Crown Copyright Ó 2011 Published by Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.02.031

S. Wang et al. / European Journal of Medicinal Chemistry 46 (2011) 1914e1918
1915
2. Results and discussion
complexes. The d of the C atom (C]S) shifted to down filed after
metallation (See Supporting Information Fig S3 and S4), which is
due to the thione/thiol evolution (in which a C]S double bond
changes to a more shielding C]N double bond [16]).
The complexes 1e8 were prepared by the reaction of K[AuCl4]$
H2O with 5-aryl-3-(pyridin-2-yl)-4,5-dihydropyrazole-1-carbo-
thioamide (L1eL8) in CH3CN (as shown in Scheme 1).
The elemental analysis data of the complexes 1e8 are in good
agreement with the calculated values. The molar conductances
(80.3e101.3 Uꢀ1 cm2 molꢀ1) for the complexes 1e8 correspond to
1:1 electrolytes [13].
As listed in Table 1, the thermal behaviour of the complexes 1e8
are similar. The mass loss (5.88e7.76 and 5.05e7.37%) in the first
two stages (79e220 and 155e245 ꢂC) corresponds to the loss of
two HCl molecules. The 51.09e54.96% mass loss in the last stage at
225e940 ꢂC coincides with the organic ligands of the complexes.
The 64.57e68.66% total mass loss suggests the residue may be gold.
Based on all the above physical and spectral studies and relative
literatures [13e17], we propose a tentative coordination mode for
the complexes (Fig. 1).
As listed in Table 2, it can be seen that the complexes 1e8 exert
cytotoxic effects against tested carcinoma cell lines with a lower IC50
value. The cytotoxicities of the complexes 1e8 are less active than
that of cisplatin against A549 cell line. The complexes 2, 3 and 6 have
weaker cytotoxicity than cisplatin, but the complexes 1, 4, 5, 7 and 8
have higher cytotoxicity than cisplatin against HeLa cell line.
In addition, the position and electronic effects of substituent
group (R) on benzene of complexes shows important influence on
cytotoxicity. For A549 cell line, when R is electron-withdrawing
groups on meta-position (2 and 4) or electron-donating groups on
para-position (5), the complexes show higher cytotoxicity. For HeLa
cell line, when R are electron-withdrawing groups on ortho-posi-
tion or meta-position (1 and 4) or R are electron-donating groups
on para-position (5 and 7) have higher cytotoxicity, the complex
whose benzene is unsubstituted (8) also exhibits high cytotoxicity
toward the HeLa cell line. The effect of substituent groups on py and
dhpy remained to be further studied.
The IR spectra of the complexes 1e8 are similar. The band of yNH
in the complexes 1e8 shifted to lower frequencies than those of
free amide group, the band of yC
] disappeared and a new band
S
appeared at 1593e1614 cmꢀ1 (C]NeH), indicating that the thione
have evolved to thiol. After complexation, the strong and sharp
band of yCeH (py) in 3139e3167 cmꢀ1 became to a weak broad band
in 3035e3092 cmꢀ1, the bands of yC
]
(py) in 1585e1606 cmꢀ1
N
and yC
]
(dhpy) in 1526e1566 cmꢀ1 shifted to 1612e1620 and
N
1531e1593 cmꢀ1, a new band corresponding to yAueN appeared in
410e424 cmꢀ1 [14], suggesting that py and dhpy coordinated with
gold through nitrogen atom. The bands of yAueS and yAueCl are not
observed for being in far-infrared region [15].
The UVeVis spectra of ligands and complexes in methanol were
measured. At a concentration of 1 ꢁ10ꢀ4 M, three main absorption
peaks at about 209, 230 and 329 nm for ligands are assigned to
internal p-p
* type transition of substituted benzene, C]S and the
conjugated system of py with C]N (dhpy), respectively. After the
formation of complexes, the peak at about 209 nm has little change,
confirming that the coordination has negligible effect on the UV
characteristic of substituted benzene. The disappearance of the
peak at about 230 nm may be caused by ligands stabilisation in the
thiol form. The peak at 329 nm blue shifts by 7 nm, indicates that py
and dhpy coordinate with gold through nitrogen atom. A shoulder
peak appears at about 334 nm may be caused by charge transfer
3. Conclusion
transition (metal w ligand) from gold d-orbital to a p
* orbital of
In conclusion, the gold(III) complexes of 5-aryl-3-(pyridin-2-yl)-
4,5-dihydropyrazole-1-carbothioamide derivatives have showed
cytotoxicity against HeLa and A549 cell lines. It is to be pointed that,
some of the complexes (1, 4, 5, 7, and 8) show higher cytotoxicity
against HeLa cells than cisplatin. In addition, the position and
electronic effects of substituent group (R) on benzene of complexes
shows important influence on cytotoxicity. The results indicated
that gold(III) complexes with 4,5-dihydropyrazole derivative might
be a promising source of metal-based antitumor agents. Current
studies are ongoing in our laboratory in order to gain a better
insight in the mechanism of action of these gold(III) complexes,
the conjugated system of py with C]N (dhpy). Then the concen-
tration is raised to 8 ꢁ 10ꢀ4 M, a new peak is found at about 407 nm
which could be assigned to ded transition of gold(III).
In 1H NMR spectra, the
d of protons of the complexes 1e8 shifts
to down field compared to free ligands. The two broad singlets in
8.13e8.24 and 6.94e8.09 ppm regions of eNH2 (2H) are shifted to
8.09e9.04 and 8.76e8.87 ppm regions attributed to pC]NH (1H),
which indicated that the thione of ligand tautomerized to thiol after
complexation (See Supporting Information Fig. S1 and S2). The 13C
NMR spectra further provide support for the structure of the
Scheme 1. The synthetic routes of the complexes (1e8).

1916
S. Wang et al. / European Journal of Medicinal Chemistry 46 (2011) 1914e1918
Table 1
Thermal analytical data of the complexes (1e8) with increasing rate of temperature of 10 ꢂC minꢀ1
.
Complex Temp. range (ꢂC) Mass loss/% Found temp. range (ꢂC) Mass loss/% Found Temp. range (ꢂC) Mass loss/% Found Total mass loss/% Found Residue
(calc.)
(calc.)
(calc.)
(calc.)
1
2
3
4
5
6
7
8
79e210
95e155
90e205
84e220
100e155
83e215
85e190
90e190
5.88 (6.08)
5.91 (6.08)
6.69 (6.08)
6.23 (5.98)
7.76 (6.13)
6.40 (5.99)
6.54 (6.31)
6.06 (6.44)
210e240
155e225
205e225
220e235
155e245
215e235
190e235
190e235
6.68 (6.08)
7.11 (6.08)
5.53 (6.08)
5.05 (5.98)
5.16 (6.13)
7.43 (5.99)
7.37 (6.31)
6.94 (6.44)
240e940
225e625
225e930
235e870
245e920
235e800
235e635
235e620
53.81 (54.07)
54.96 (54.07)
52.64 (54.07)
57.38 (54.88)
51.63 (53.71)
53.97 (54.81)
51.09 (52.40)
53.98 (51.18)
66.37 (66.23)
67.98 (66.23)
64.86 (66.23)
68.66 (66.84)
64.57 (65.97)
67.80 (66.79)
65.00 (65.02)
66.98 (64.06)
Au
Au
Au
Au
Au
Au
Au
Au
which may be helpful for the design of new metal-based antitumor
agents.
thiosemicarbazide is refluxed in 5 mL ethanol under vigorous
stirring. After complete dissolution of the reactants, a solution of
0.112 g (0.002 mol) KOH in 2 mL ethanol is added dropwise. The
solution is refluxed for a further 1 h. A precipitate is formed when
the solution is cool, which is filtered off and crystallized from
4. Experimental section
ethanol to give L1 as
a pure product. L1: yield: 88.5%;
4.1. Materials
m.p:221e223 ꢂC; yellow solid; IR (KBr, cmꢀ1): 3403e3260 (NeH),
3148 (CeH, py), 1593 (C]N, py), 1563 (C]N, dhpy), 1349 (C]S); 1H
All chemicals and reagents were of analytical grade. RPMI-1640
medium, trypsin and fetal bovine serum were purchased from
Gibco. MTT, penicillin and streptomycin were from sigma. Two
different human carcinoma cell lines: HeLa (cervix carcinoma) and
A549 (lung cancer) were obtained from American Type Culture
Collection.
NMR (600 MHz, DMSO-d6)
d 8.58e8.59 (m, 1H, py-H), 8.28 (d, 2H,
py-H), 8.13 (br s, 1H, NH), 7.89e7.92 (m, 1H, py-H), 7.44e7.49 (m,
2H, ph-H), 7.26e7.29 (m, 2H, ph-H), 6.94 (br s, 1H, NH), 6.15 (dd,1H,
JAx ¼ 3.8 Hz, JBx ¼ 11.6 Hz, Hx), 4.03 (dd,1H, JBx ¼ 11.6 Hz,
JAB ¼ 18.4 Hz, HB), 3.04 (dd,1H, JAx ¼ 3.8 Hz, JAB ¼ 18.4 Hz, HA); 13
C
NMR (150 MHz, DMSO-d6)
d 41.6, 61.5, 122.0, 125.5, 127.9, 129.2,
130.2, 130.7, 137.2, 140.0, 150.0, 150.3, 156.3, 177.0; ESI-MS: 339.0
4.2. Instrumentation and measurement
[M þ Na]þ.
L2 was carried out in an identical manner to L1. L2: yield: 85.9%;
m.p:168e169 ꢂC; light yellow solid; IR (KBr, cmꢀ1): 3425e3260
(NeH), 3152 (CeH, py), 1593 (C]N, py), 1563 (C]N, dhpy), 1349
Melting points were determined on an XT-4 microscopic
melting-point spectrometer and are uncorrected. Elemental anal-
yses were determined on an Elementar Vario EL III elemental
analyzer. Molar conductances at room temperature were measured
in 10ꢀ3 M methanol solutions using a DDS-12DW type conductivity
meter. The IR spectra were recorded using KBr pellets and a Per-
kineElmer Model-683 spectrophotometer. The UVeVis spectra at
room temperature were measured in methanol solutions using
a TU-1901 double beam UVeVis spectrophotometer (Beijing Pur-
kinje General Instrument Co., Ltd). The 1H NMR and 13C NMR
spectra were recorded on a Bruker AVIII 600 NMR spectrometer.
The mass spectra were measured by LC-MS apparatus Agilent
1200e6310. The thermal analysis was conducted using Netzsch
(Germany) TG209c (N2, 10 ꢂC minꢀ1, Al2O3). The OD was measured
on a microplate spectrophotometer (Bio-Rad Model 680, USA).
(C]S); 1H NMR (600 MHz, DMSO-d6)
d 8.59e8.61 (m, 1H, py-H),
8.29 (d, 1H, py-H), 8.24 (br s, 1H, NH), 8.09 (br s, 1H, NH),7.90e7.93
(m, 1H, py-H), 7.45e7.47 (m, 1H, py-H), 7.36 (t, 1H, ph-H), 7.29e7.31
(m, 1H, ph-H), 7.17 (t, 1H, ph-H), 7.10e7.11 (m, 1H, ph-H), 5.94
(dd,1H, JAx ¼ 3.7 Hz, JBx ¼ 11.6 Hz, Hx), 4.03 (dd,1H, JBx ¼ 11.6 Hz,
JAB ¼ 18.7 Hz, HB), 3.04 (dd,1H, JAx ¼ 3.7 Hz, JAB ¼ 18.7 Hz, HA); 13
C
NMR (150 MHz, DMSO-d6)
d 42.3, 62.6, 121.6, 123.9, 124.9, 125.2,
126.9, 130.6, 133.0, 136.7, 145.3, 149.5, 149.9, 155.7, 176.5; ESI-MS:
339.1 [M þ Na]þ.
L3 was carried out in an identical manner to L1. L3: yield: 91.0%;
m.p:185e187 ꢂC; white solid; IR (KBr, cmꢀ1): 3414e3270
(NeH),3156 (CeH, py), 1602 (C]N, py), 1565 (C]N, dhpy), 1343
(C]S); 1H NMR (600 MHz, DMSO-d6)
d 8.60e8.61 (m,1H, py-H), 8.29
(d,1H, py-H), 8.24 (br s,1H, NH), 8.08 (br s,1H, NH),7.90e7.93 (m,1H,
py-H), 7.45e7.47 (m, 1H, py-H), 7.36e7.39 (m, 2H, ph-H), 7.15e7.18
(m, 2H, ph-H), 5.93(dd,1H, JAx ¼ 3.7 Hz, JBx ¼ 11.6 Hz, Hx), 3.95 (dd,1H,
JBx ¼ 11.6 Hz, JAB ¼ 18.6 Hz, HB), 3.13 (dd,1H, JAx ¼ 3.7 Hz, JAB ¼ 18.6 Hz,
4.3. Synthesis of ligands
The azachalcones have been prepared as described in the liter-
ature [18].
The ligands L1eL8 was prepared as described in the literature
[19]. A mixture of 0.243 g (0.001 mol) of (E)-3-(2-chlorophenyl)-1-
HA); 13C NMR (150 MHz, DMSO-d6)
d 42.2, 62.5, 121.6, 124.9, 127.3,
128.5, 131.4, 136.7, 141.8, 149.5, 149.9, 155.7, 176.5; ESI-MS: 339.0
[M þ Na]þ.
(pyridin-2-yl) prop-2-en-1-one and 0.182
g
(0.002 mol) of
Table 2
The cytotoxicity of the complexes (1e8) against A549 and HeLa cell lines.
+
Complex
IC50
(
mM) ðx ꢃ SDÞ
A549
HeLa
6.86 ꢃ 0.18
N
-
cisplatin
4.66 ꢃ 0.07
36.23 ꢃ 1.04
7.18 ꢃ 0.22
34.21 ꢃ 0.38
10.04 ꢃ 0.39
12.69 ꢃ 0.30
12.73 ꢃ 0.13
29.22 ꢃ 0.76
51.18 ꢃ 3.21
Cl
N
1
2
3
4
5
6
7
8
3.86 ꢃ 0.13
8.60 ꢃ 0.15
8.70 ꢃ 0.49
3.91 ꢃ 0.10
2.55 ꢃ 0.08
13.82 ꢃ 0.42
5.14 ꢃ 0.18
4.41 ꢃ 0.37
N
R
Au
Cl
S
NH
R=2-Cl, 3-Cl, 4-Cl, 3-NO2, 4-OCH3, 3, 4-OCH2O, 4-CH3,
H
Fig. 1. Tentative coordination mode of the complexes.

S. Wang et al. / European Journal of Medicinal Chemistry 46 (2011) 1914e1918
1917
L4 was carried out in an identical manner to L1. L4: yield:
69.7%; m.p:226e227 ꢂC; yellow solid; IR (KBr, cmꢀ1): 3416e3295
(NeH), 3167 (CeH, py), 1596 (C]N, py), 1526 (C]N, dhpy), 1344
NH), 8.87 (s, 0.5H, NH), 8.66 (d, 1H, py-H), 8.37 (d, 1H, py-H),
8.11e8.17 (m, 1H, py-H), 8.01e8.04 (m, 1H, py-H), 7.56e7.58 (m, 1H,
ph-H), 7.53e7.55(m,1H, ph-H), 7.34e7.39 (m, 2H, ph-H),6.14 (dd,1H,
JAx ¼ 3.6 Hz, JBx ¼ 11.4 Hz, Hx), 4.19 (dd,1H, JBx ¼ 11.4 Hz, JAB ¼ 19.2 Hz,
HB), 3.22 (dd,1H, JAx ¼ 3.6 Hz, JAB ¼ 19.2 Hz, HA); 13C NMR (150 MHz,
(C]S); 1H NMR (600 MHz, DMSO-d6)
d 8.60e8.61 (m,1H, py-H), 8.31
(d, 1H, py-H), 8.16 (br s,1H, NH), 8.10e8.13 (m, 1H, py-H), 7.99 (t,1H,
py-H), 7.92e7.94 (t, 1H, ph-H), 7.69 (br s, 1H, NH), 7.63e7.66 (m, 2H,
ph-H), 7.46e7.48 (m, 1H, ph-H), 6.10 (dd,1H, JAx ¼ 4.2 Hz,
JBx ¼ 11.8 Hz, Hx), 3.95 (dd, 1H, JBx ¼ 11.8 Hz, JAB ¼ 18.8 Hz, HB), 3.13
(dd,1H, JAx ¼ 4.2 Hz, JAB ¼ 18.8 Hz, HA); 13C NMR (150 MHz, DMSO-d6)
DMSO-d6)
d 42.3, 61.8, 122.6, 125.9, 127.9, 129.5, 130.2, 130.5, 137.7,
148.5, 149.2, 149.3, 151.0, 197.5; Anal. Calc. for C15H12N4AuCl3S: C,
30.84; H, 2.06; N, 9.59. Found: C, 30.81; H, 1.77; N, 9.41.
The synthesis of 2 was carried out in an identical manner to 1. 2:
Yield: 61.6%; IR (KBr, cmꢀ1): 3088 (CeH, py), 1619 (C]N, py), 1591
(C]N, dhpy), 1614 (C]N, pC]NeH), 414 (AueN); 1H NMR
d
42.1, 62.5, 120.2, 121.6, 122.0, 125.0, 130.2, 132.3, 136.7, 145.0, 147.8,
149.5, 149.8, 155.8, 176.6; ESI-MS: 350.0 [M þ Na]þ.
L5 was carried out in an identical manner to L1. L5: yield: 66.9%;
m.p:197e199 ꢂC; light yellow solid; IR (KBr, cmꢀ1): 3397e3262
(NeH), 3162 (CeH, py), 1606 (C]N, py), 1559 (C]N, dhpy), 1345
(600 MHz, DMSO-d6) d 8.94 (s, 0.5H, NH), 8.75 (s, 0.5H, NH), 8.68 (d,
1H, py-H), 8.37 (d,1H, py-H), 8.06 (t,1H, py-H), 7.60 (t,1H, py-H), 7.41
(t,1H, ph-H), 7.36 (d,1H, ph-H), 7.27 (s, 1H, ph-H), 7.15 (d,1H, ph-H),
5.95 (dd,1H, JAx ¼ 3.6 Hz, JBx ¼ 11.4 Hz, Hx), 4.10 (dd,1H, JBx ¼ 11.4 Hz,
(C]S); 1H NMR (600 MHz, DMSO-d6)
d 8.60e8.61 (m,1H, py-H), 8.29
(d,1H, py-H), 8.12 (br s,1H, NH), 7.99 (br s,1H, NH), 7.90e7.93 (m,1H,
py-H), 7.45e7.47 (m, 1H, py-H), 7.05e7.08 (m, 2H, ph-H), 6.86e6.88
(m, 2H, ph-H), 5.89 (dd, 1H, JAx ¼ 3.7 Hz, JBx ¼ 11.5 Hz, Hx), 3.90 (dd,
1H, JBx ¼ 11.5 Hz, JAB ¼ 18.6 Hz, HB), 3.72 (s, 3H, OCH3), 3.13 (dd,1H,
JAB ¼ 18.6 Hz, HB), 3.22 (dd,1H, JAx ¼ 3.6 Hz, JAB ¼ 18.6 Hz, HA); 13
C
NMR (150 MHz, DMSO-d6)
d 43.3, 63.5, 122.8, 124.0, 125.4, 125.9,
127.7, 130.9, 133.4, 138.06, 138.1, 148.2, 148.8, 206.6; Anal. Calc. for
C15H12N4AuCl3S: C, 30.84; H, 2.06; N, 9.59. Found: C, 30.38; H, 2.24;
N, 9.50.
The synthesis of 3 was carried out in an identical manner to 1. 3:
Yield: 58.2%; IR (KBr, cmꢀ1): 3082 (CeH, py), 1619 (C]N, py), 1593
(C]N, dhpy), 1613 (C]N, pC]NeH), 410 (AueN); 1H NMR
JAx ¼ 3.7 Hz, JAB ¼ 18.6 Hz, HA); 13C NMR (150 MHz, DMSO-d6)
d 42.9,
55.5, 63.1, 114.3, 122.0, 125.3, 127.1, 135.4, 137.2, 150.0, 150.6, 156.3,
158.7, 177.0; ESI-MS: 335.1 [M þ Na]þ.
L6 was carried out in an identical manner to L1. L6: yield: 90.8%;
m.p:178e179 ꢂC; white solid; IR (KBr, cmꢀ1): 3431e3253 (NeH),
3139 (CeH, py), 1585 (C]N, py), 1567 (C]N, dhpy), 1350 (C]S); 1H
(600 MHz, DMSO-d6) d 9.01 (s, 0.5H, NH), 8.84 (s, 0.5H, NH), 8.69 (d,
1H, py-H), 8.38 (d,1H, py-H), 8.06 (t,1H, py-H), 7.59e7.61 (m,1H, py-
H), 7.44 (d, 2H, ph-H), 7.23 (d, 2H, ph-H), 5.94 (dd,1H, JAx ¼ 3.6 Hz,
JBx ¼ 11.4 Hz, Hx), 4.11 (dd, 1H, JBx ¼ 11.4 Hz, JAB ¼ 19.2 Hz, HB), 3.29
(dd,1H, JAx ¼ 3.6 Hz, JAB ¼ 19.2 Hz, HA); 13C NMR (150 MHz, DMSO-d6)
NMR (600 MHz, DMSO-d6) d 8.60e8.61 (m,1H, py-H), 8.28 (d,1H, py-
H), 8.18 (br s, 1H, NH), 8.03 (br s, 1H, NH), 7.90e7.93 (m, 1H, py-H),
7.45e7.47 (m, 1H, py-H), 6.84 (d, 1H, ph-H), 6.67 (d, 1H, ph-H), 6.61
(dd, 1H, ph-H), 5.98 (d, 2H, OCH2O), 5.85 (dd, 1H, JAx ¼ 3.8 Hz,
JBx ¼ 11.5 Hz, Hx), 3.83 (dd, 1H, JBx ¼ 11.5 Hz, JAB ¼ 18.6 Hz, HB), 3.12
(dd,1H, JAx ¼ 3.8 Hz, JAB ¼ 18.6 Hz, HA); 13C NMR (150 MHz, DMSO-d6)
d
43.4, 63.5,122.8,125.9,127.4,128.9,132.3,137.9,138.0,148.3,148.9,
149.0, 203.2; Anal. Calc. for C15H12N4AuCl3S: C, 30.84; H, 2.06; N,
9.59. Found: C, 30.39; H, 2.31; N, 9.33.
The synthesis of 4 was carried out in an identical manner to 1. 4:
Yield: 62.3%; IR (KBr, cmꢀ1): 3090 (CeH, py), 1620 (C]N, py), 1531
(C]N, dhpy), 1594 (C]N, pC]NeH), 412 (AueN); 1H NMR
d
42.4, 62.9, 100.9, 105.9, 108.2, 118.3, 121.5, 124.8, 136.7, 136.8, 146.1,
147.3, 149.5, 150.0, 155.8, 176.5; ESI-MS: 349.0 [M þ Na]þ.
L7 was carried out in an identical manner to L1. L7: yield: 81.1%;
m.p:153e154 ꢂC; white solid; IR (KBr, cmꢀ1): 3407e3276 (NeH),
3155 (CeH, py), 1597 (C]N, py), 1566 (C]N, dhpy), 1342 (C]S); 1H
(600 MHz, DMSO-d6) d 9.04 (s, 0.5H, NH), 8.87 (s, 0.5H, NH), 8.69 (d,
1H, py-H), 8.19 (d,1H, py-H), 8.16e8.18 (m,1H, py-H), 8.06e8.07 (m,
2H, a py-H and a ph-H), 7.67e7.70 (m, 2H, ph-H), 7.59e7.62 (m, 1H,
ph-H), 6.12 (dd,1H, JAx ¼ 3.6 Hz, JBx ¼ 11.4 Hz, Hx), 4.14 (dd, 1H,
JBx ¼ 11.4 Hz, JAB ¼ 18.6 Hz, HB), 3.36 (dd,1H, JAx ¼ 3.6 Hz,
NMR (600 MHz, DMSO-d6) d 8.59e8.60 (m,1H, py-H), 8.29 (d,1H, py-
H), 8.16 (br s, 1H, NH), 8.03 (br s, 1H, NH), 7.90e7.93 (m, 1H, py-H),
7.44e7.46 (m, 1H, py-H), 7.11 (d, 2H, ph-H), 7.02 (d, 2H, ph-H), 5.90
(dd, 1H, JAx ¼ 3.7 Hz, JBx ¼ 11.5 Hz, Hx), 3.91 (dd, 1H, JBx ¼ 11.5 Hz,
JAB ¼ 18.6 Hz, HB), 3.11 (dd,1H, JAx ¼ 3.7 Hz, JAB ¼ 18.6 Hz, HA), 2.26 (s,
JAB ¼ 18.6 Hz, HA); 13C NMR (150 MHz, DMSO-d6)
d 43.0, 63.2, 115.1,
120.5, 122.6, 122.7, 122.9, 125.9, 130.6, 130.8, 132.3, 148.0, 148.2,
148.3, 203.4; Anal. Calc. for C15H12O2N5AuCl2S: C, 30.33; H, 2.02; N,
11.78. Found: C, 30.43; H, 2.06; N, 11.55; ESI-MS: 635.4
[M þ H2O þ Na]þ.
3H, CH3); 13C NMR (150 MHz, DMSO-d6)
d 20.6, 42.4, 62.8, 121.5,
124.8, 125.1, 129.0, 136.0, 136.7, 139.9, 149.0, 150.0, 155.7, 176.5; ESI-
MS: 319.1 [M þ Na]þ.
L8 was carried out in an identical manner to L1. L8: yield: 94.3%;
m.p:210e211 ꢂC; light yellow solid; IR (KBr, cmꢀ1): 3378e3269
(NeH), 3156 (CeH, py), 1604 (C]N, py), 1565 (C]N, dhpy), 1345
The synthesis of 5 was carried out in an identical manner to 1. 5:
Yield: 55.3%; IR (KBr, cmꢀ1): 3092 (CeH, py), 1612 (C]N, py), 1577
(C]N, dhpy), 1595 (C]N, pC]NeH), 421 (AueN); 1H NMR
(C]S); 1H NMR (600 MHz, DMSO-d6)
d
8.59e8.60 (m,1H, py-H), 8.29
(600 MHz, DMSO-d6) d 8.92 (s, 0.5H, NH), 8.76 (s, 0.5H, NH), 8.68 (d,
(d,1H, py-H), 8.17 (br s,1H, NH), 8.04 (br s,1H, NH), 7.90e7.93 (m,1H,
py-H), 7.44e7.46 (m,1H, py-H),, 7.31 (t, 2H, ph-H), 7.23 (t,1H, ph-H),
7.14 (d, 2H, ph-H), 5.95 (dd, 1H, JAx ¼ 3.6 Hz, JBx ¼ 11.4 Hz, Hx), 3.94
(dd, 1H, JBx ¼ 11.4 Hz, JAB ¼ 18.6 Hz, HB), 3.13 (dd,1H, JAx ¼ 3.6 Hz,
1H, py-H), 8.38 (d,1H, py-H), 8.03 (t,1H, py-H), 7.57e7.59 (m,1H, py-
H), 7.12 (d, 2H, ph-H), 6.92 (d, 2H, ph-H), 5.86 (dd,1H, JAx ¼ 3.6 Hz,
JBx ¼ 10.8 Hz, Hx), 4.08 (dd,1H, JBx ¼ 10.8 Hz, JAB ¼ 18.6 Hz, HB), 3.76 (s,
3H, OCH3),3.27 (dd,1H, JAx ¼ 3.6 Hz, JAB ¼ 18.6 Hz, HA); 13C NMR
JAB ¼ 18.6 Hz, HA); 13C NMR (150 MHz, DMSO-d6)
d
42.9, 63.6, 122.0,
(150 MHz, DMSO-d6) d 43.5, 55.1, 63.6, 114.2, 122.6, 125.8, 126.8,
125.4, 125.7, 127.4, 129.0, 137.2, 143.3, 150.0, 156.2, 177.0; ESI-MS:
137.7, 148.6, 149.1, 149.2, 154.7, 158.7, 187.1; Anal. Calc. for
C16H15ON4AuCl2S: C, 33.16; H, 2.59; N, 9.67. Found: C, 32.86; H, 2.78;
N, 9.47.
305.1 [M þ Na]þ.
4.4. Synthesis of gold(III) complexes
The synthesis of 6 was carried out in an identical manner to 1. 6:
Yield: 56.7%; IR (KBr, cmꢀ1): 3036 (CeH, py), 1620 (C]N, py), 1569
(C]N, dhpy), 1593 (C]N, pC]NeH), 413 (AueN); 1H NMR
To a rapidly stirred solution of K[AuCl4]$H2O (40 mg, 0.1 mmol) in
3 mL CH3CN, the solution of L1 (31 mg, 0.1 mmol) in 3 mL CH3CN was
added in room temperature. After further 6 h, the resulting yellow
precipitate was filtered. The collected solid was washed with cold
CH3CN (3 ꢁ 3 mL) and dried to give 1.1: Yield: 51.4%; IR (KBr, cmꢀ1):
3089 (CeH, py),1617 (C]N, py),1590 (C]N, dhpy),1612 (C]N, pC]
(600 MHz, DMSO-d6) d 9.02 (s, 0.5H, NH), 8.83 (s, 0.5H, NH), 8.67 (d,
1H, py-H), 8.38 (d,1H, py-H), 8.00e8.03 (m,1H, py-H), 7.56e7.58 (m,
1H, py-H), 6.89 (d, 1H, ph-H), 6.75 (d, 1H, ph-H), 6.67(dd, 1H, ph-H),
6.02 (d, 2H, OCH2O), 5.82 (dd,1H, JAx ¼ 3.6 Hz, JBx ¼ 11.4 Hz, Hx), 4.08
(dd, 1H, JBx ¼ 11.4 Hz, JAB ¼ 18.6 Hz, HB), 3.28 (dd, 1H, JAx ¼ 3.6 Hz,
NeH), 412 (AueN); 1H NMR (600 MHz, DMSO-d6)
d
9.04 (s, 0.5H,
JAB ¼ 18.6 Hz, HA); 13C NMR (150 MHz, DMSO-d6)
d 43.7, 63.1, 101.2,

1918
S. Wang et al. / European Journal of Medicinal Chemistry 46 (2011) 1914e1918
105.9,106.8,108.2,118.8,122.6,125.8,137.4,137.5,146.8,147.8,148.7,
149.3, 149.4, 178.8; Anal. Calc. for C16H14N4O2AuCl2S: C, 32.38; H,
2.19; N, 9.44. Found: C, 31.92; H, 2.47; N, 9.14; ESI-MS: 634.3
[M þ H2O þ Na]þ.
described by Mosmann [20]. Upon completion of the incubation for
44 h, stock MTT dye solution (20 mL, 5 mg/mL) was added to each
well. After 4 h incubation, 2-propanol (100 mL) was added to
solubilize the MTT formazan. The OD of each well was measured on
a microplate spectrophotometer at a wavelength of 570 nm. The
IC50 value was determined from plot of % viability against dose of
compounds added.
The synthesis of 7 was carried out in an identical manner to 1. 7:
Yield: 64.1%; IR (KBr, cmꢀ1): 3080 (CeH, py), 1620 (C]N, py), 1593
(C]N, dhpy), 1614 (C]N, pC]NeH), 410 (AueN); 1H NMR
(600 MHz, DMSO-d6) d 8.99 (s, 0.5H, NH), 8.83 (s, 0.5H, NH), 8.69 (d,
1H, py-H), 8.39 (d,1H, py-H), 8.07 (t,1H, py-H), 7.60e7.62 (m,1H, py-
H), 7.17 (d, 2H, ph-H), 7.08 (d, 2H, ph-H), 5.89 (dd,1H, JAx ¼ 3.6 Hz,
JBx ¼ 11.4 Hz, Hx), 4.09 (dd, 1H, JBx ¼ 11.4 Hz, JAB ¼ 18.6 Hz, HB), 3.27
(dd,1H, JAx ¼ 3.6 Hz, JAB ¼ 18.6 Hz, HA); 13C NMR (150 MHz, DMSO-d6)
Acknowledgements
This work was supported by the Special Foundation for State
Major New Drug Research Program of China (Grant No.
2009ZX09103-139), the National Basic Research 973 Program
(Grant No. 2010CB534913), Natural Science Foundation of Hebei
Province (Grant No. B2011201135), Nature Science Foundation for
Distinguished Young Scholars of Hebei Province (Grant No.
B2011201164), the Key Research Project Foundation of Departe-
ment of Education of Hebei Province (Grant No. ZD2010142).
d
19.6, 42.3, 62.8, 121.8, 124.3, 124.8, 125.2, 128.3, 136.0, 137.1, 137.2,
147.0, 147.6, 203.0; Anal. Calc. for C16H15N4AuCl2S: C, 34.10; H, 2.66;
N, 9.95. Found: C, 34.44; H, 3.11; N, 10.25.
The synthesis of 8 was carried out in an identical manner to 1. 8:
Yield: 54.7%; IR (KBr, cmꢀ1): 3035 (CeH, py), 1620 (C]N, py), 1591
(C]N, dhpy),1614 (C]N, pC]NeH), 412 (AueN); 1H NMR (600 MHz,
DMSO-d6)
d 9.00 (s, 0.5H, NH), 8.83 (s, 0.5H, NH), 8.69 (d, 1H, py-H),
8.39 (d, 1H, py-H), 8.07 (t, 1H, py-H), 7.60e7.62 (m, 1H, py-H), 7.38 (t,
2H, ph-H), 7.31(t, 1H, ph-H), 7.20 (d, 2H, ph-H), 5.94 (dd,1H,
JAx ¼ 3.6 Hz, JBx ¼ 11.4 Hz, Hx), 4.12 (dd,1H, JBx ¼ 11.4 Hz, JAB ¼ 18.6 Hz,
HB), 3.29 (dd, 1H, JAx ¼ 3.6 Hz, JAB ¼ 18.6 Hz, HA); 13C NMR (150 MHz,
Appendix. Supplementary material
Supplementary data related to this article can be found online at
doi:10.1016/j.ejmech.2011.02.031.
DMSO-d6)
d 43.5, 64.1, 122.8, 125.3, 125.9, 126.3, 127.8, 128.9, 138.1,
140.2, 148.2, 148.9, 202.8; Anal. Calc. for C15H13N4AuCl2S: C, 32.79; H,
2.37; N, 10.20. Found: C, 32.43; H, 2.54; N, 9.86.
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The cells harvested from exponential phase were seeded
equivalently into a 96-well plate, and then the complexes were
added to the wells to achieve final concentrations. Control wells
were prepared by addition of culture medium. Wells containing
culture medium without cells were used as blanks. All experiments
were performed in quintuplicate. The MTT assay was performed as