Design, synthesis and biological evaluation of novel estrogen-derived steroid metal complexes

Article abstract of DOI:10.1016/j.bmcl.2013.04.088

A new series of estrogen-derived metal complexes were synthesized and characterized. The functionalized estrogen receptor ligands were prepared by a four-step synthetic strategy, and then three transition metal Pd, Ni, Zn were introduced readily to give t

Full text of DOI:10.1016/j.bmcl.2013.04.088

Accepted Manuscript
Design, Synthesis and Biological Evaluation of Novel Estrogen-derived Steroid
Metal Complexes
Xinlong Zhang, ZiqingZuo, Juan Tang, Kai Wang, Caihua Wang, Weiyan Chen,
Changhao Li, Wen Xu, Xiaolin Xiong, Kangxiang Yuntai, Jian Huang, Xiaoli
Lan, Hai-Bing Zhou
PII:
S0960-894X(13)00580-5
DOI:
http://dx.doi.org/10.1016/j.bmcl.2013.04.088
BMCL 20455
Reference:
To appear in:
Bioorganic & Medicinal Chemistry Letters
Received Date:
Revised Date:
Accepted Date:
18 October 2012
26 April 2013
30 April 2013
Please cite this article as: Zhang, X., Zuo, Z., Tang, J., Wang, K., Wang, C., Chen, W., Li, C., Xu, W., Xiong, X.,
Yuntai, K., Huang, J., Lan, X., Zhou, H-B., Design, Synthesis and Biological Evaluation of Novel Estrogen-derived
Steroid Metal Complexes, Bioorganic & Medicinal Chemistry Letters (2013), doi: http://dx.doi.org/10.1016/j.bmcl.
2013.04.088
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Design, Synthesis and Biological Evaluation of Novel
Estrogen-derived Steroidal Metal Complexes
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Xinlong Zhang,a Ziqing Zuo,a Juan Tang,a Kai Wang,a Caihua Wang,b Weiyan Chen,a
Changhao Li,b Wen Xu,b Xiaolin Xiong,a Kangxiang Yuntai,a Jian Huang,b Xiaoli Lan,c Hai-Bing Zhoua*

Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com
Design, Synthesis and Biological Evaluation of Novel Estrogen-derived Steroid
Metal Complexes
Xinlong Zhang,a Ziqing Zuo,a Juan Tang,a Kai Wang,a Caihua Wang,b Weiyan Chen,a Changhao Li,b Wen
Xu,b Xiaolin Xiong,a Kangxiang Yuntai,a Jian Huang,b Xiaoli Lan,c Hai-Bing Zhoua*
a State Key Laboratory of Virology, Key Laboratory of Combinatorial Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education, Wuhan
University School of Pharmaceutical Sciences, Wuhan, 430071, China
b College of Life Sciences, Wuhan University, Wuhan, 430072, China
c Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430000, China
ARTICLE INFO
ABSTRACT
A new series of estrogen-derived metal complexes were synthesized and characterized. The
functionalized estrogen receptor ligands were prepared by a four-step synthetic strategy, and
then three transition metal Pd, Ni, Zn were introduced readily to give the title metal complexes,
in which the squaramide was introduced as ion acceptor for the first time in the development of
estrogen-derived metal complexes for estrogen receptor. Upon binding to estrogen receptors,
all of the estrogen conjugates exhibited acceptable binding affinity (up to 2.3% relative to
Estradiol), and in transcription assays, all the compounds are agonists on ERα. Molecular
modeling studies suggest a structural basis for the agonist activity of these compounds.
Article history:
Received
Revised
Accepted
Available online
Keywords:
breast cancer
estrogen
squaric acid
metal complex
2012 Elsevier Ltd. All rights reserved.
The steroid hormone estrogens play key roles not only in the
maintenance of normal sexual and reproductive function but also
in the progression of numerous diseases through regulation of the
transcriptional activity of its cognate receptors[1]. Classically,
most of the actions of estrogens appear to be exerted via two
estrogen receptor (ER) subtypes, denoted ERa and ER, which
bind as dimers to estrogen-response elements in the regulatory
regions of the estrogen-responsive genes and associate with basal
transcription factors and coregulators to alter gene expression[2],
though recently much evidence has shown some other
pathways[3]. Ever since the link between human breast cancer and
estrogen emerged over a century ago, people have realized that
hormones are key contributors to carcinogenesis in specific
cancers[4]. An association between the risk of breast cancer and
persistently elevated blood level of estrogen has been
consistently found in many studies[5]. Estrogen stimulates the
proliferation of breast epithelial cells, and both endogenous and
exogenous estrogens have been implicated in the pathogenesis of
breast cancer[6].
prolonged imaging. Moreover, the ability of these metal
complexes to deliver metal centers across the cellular membrane
and into specific cells especially tumor cells is consequently an
important goal.
Concerning the metal chelating strategies, a variety of
conjugating scaffolds have been reported before[7a-c]. With a good
knowledge of the estrogen receptors and theirs ligands, we are
very interested in the linkage between the metal ion and the 17α-
position of E2. Previous studies shown that the 17α-position of E2
can tolerate bulky organometallic species without much loss of
the binding affinity to ER[9]. At the same time, an ethynyl linker
group between the estrogen 17α-position and the organometallic
moiety was proven to maintain an effective ER binding
affinity[10]
. Estrogenic steroid conjugates containing metal
chelates at 17α-position represent an attractive delivery vector for
such targeting strategy[11]. Especially, a pyridine ring linked to
the ethynyl group at the estrogen 17α-position is often utilized as
the key component of the metal chelating groups for either
potential imaging agents or SERMs (Selective Estrogen Receptor
Modulators, examples shown in Scheme 1)[12]. These design
ideas are also taken into consideration in our work.
Meanwhile, transition metal centers have been being widely
utilized as agents for diagnostic imaging and medical therapeutic
treatment both in the clinic and in research programs[7]. In recent
decades, a variety of estrogen derivatives labeled with transition
metal Pt, Re, Tc, Ru, etc[8] have been investigated as targeting
agents into ER-positive cells. In addition, metal complex as a
radionuclide which has several advantages and played a central
role in diagnostic medical imaging for several years. They can be
produced using commercially available generator systems
Our recent work, described in this report, focuses on the
search for more potent estrogen-derived metal complexes which
may have higher binding affinity and desired characteristics
including the redox properties, stability and lipophilicity. And
also, we are very interested in incorporating the squaramide
moiety into the metal complexes. It is known that the squaric acid
derivatives have been applied in a wide variety of chemistry
fields including bioconjugate chemistry, medicinal chemistry,
combined with other favorable characteristics such as
a
convenient half-life, which allows for complex synthesis and

molecular
recognition,
organometallic
chemistry
and
organocatalysis due to its unique properties [13]. Therefore, we
apply the squaramide structure as the core of metal binding unit
in our molecular design. On the other hand, since the first
application of Oxaliplatin (the first effective platinum-based
agent for the treatment of colorectal cancer[13]), great attention
has been paid on the complexes containing 1,2-
diaminocyclohexane (1,2-DACH) moiety regarding to their
anticancer activities[15,16]. It proved to be particularly convenient
to use the 1,2-cyclohexane and squaramide as metal chelating
moieties. The synthetic accessibility of the title compound is
feasible with the advantages of 1,2-diaminocyclohexane and
squaramide as building blocks.
Based on the facts above, we designed and prepared estradiol
derived squaramide ligand 6 and its metal complexes 7a-c. Their
binding affinities to the ER-LBD (estrogen receptor-ligand
binding domain) were also examined. All of the synthesized
compounds exhibited effective binding to the estrogen receptors.
The results suggested the promising application of this series of
estrogen-derived metal complexes as a novel type of targeting
agents for estrogen receptors.
Scheme 2 Synthesis of the neutral ligand 6
With the ligand 6 in hand, we tried to prepare a variety of
metal complexes 7 (Scheme 3)[12a]. For complex 7a, mixture of
ligand 6 and Pd(MeCN)2Cl2 in anhydrous CH2Cl2 solution under
argon atmosphere was stirred at ambient temperature overnight.
Then the solution was filtered and washed with CH2Cl2, which
afforded the complex 7a in 51% yield without further
purification. Compounds 7b-c were synthesized under similar
procedures in anhydrous MeOH instead of CH2Cl2 with metal
source NiCl2 and ZnCl2, respectively. The structures of
complexes 7a-c have been confirmed by IR, NMR and mass
spectrometry[20]
.
Scheme 1 Representative steroidal-derived metal complexes and
title compound 7
As shown in Scheme 2, compounds
1 and 2 were
conveniently prepared from squaric acid and 1,2-
cyclohexanediamine respectively with moderate yield (Scheme
2A and 2B)[17]. These two compounds comprised the major part
of metal chelate moiety. Sonogashira coupling reaction of 17α-
Scheme 3 Synthesis of the complexes 7a-c
ethynylestradiol
with
p-bromobenzaldehyde
afforded
Having successfully obtained the complexes 7a-c, we
wondered whether these steroidal compounds would retain
binding affinity and transcription activation for the estrogen
receptor. The estrogen receptor binding affinities of complexes
7a-c were measured by a competitive fluorescence polarization
binding assay, using both purified human ER/ER-LBD (details
shown in Supporting Information)[21]. The binding affinities of
the compound 6 and the complexes 7 in this study were
summarized in Table 1. The lipophilicity value (expressed in
logPo/w) of the compounds 6 and 7 was also calculated with the
Molecular Operating Environment (MOE) package[22]. The
logPo/w values of complexes 7a-c were calculated to be 5.38,
6.85 and 6.95, respectively. The compounds 7b and 7c were
more lipophilic than the free ligand 6 (ca. 6.16), however, 7a is
slightly less hydrophobic than 6 possibly due to its cationic
nature. The high lipophilicity of these molecules is anticipated to
be a good compromise for a potential pharmaceutical product.
corresponding product 3 in good yield. Subsequent reductive
amination of compound 3 with compound 2 produced compound
4 in 76% yield[18]. Hydrolysis of 4 with 50% TFA/CH2Cl2[19] led
to compound 5 which then reacted with 2 in EtOH to give rise to
the target neutral ligand 6 in 95% yield (Scheme 2C).

Table 1. Relative Binding Affinity (RBA) of compounds 6 and
7a-c for ERα and ERβa
force field parameters for Ni and Pd, we only modeled the
ligands of 6, 7c and estradiol into the ligand binding pocket of
both activation (PDB code: 2YAT [12d]) and inhibition (PDBcode:
2OUZ[23]) conformations of ERα. Ligand 6 can dock well with
Compoundb
ERα (%)
100
ERβ (%)
100
both the ERα conformations[24]
. The estradiol moiety in
Estradiol
compound 6 can superimpose well with estradiol (data not show).
As a result, a similar binding model achieved—the A ring forms
hydrogen bonding with Glu 353 and Arg 394, the hydroxyl group
at 17β position forms a hydrogen bond with His 524 (Figure 1
A). The rest part of ligand 6 orients to the beta sheets which
opposite to and far from helix 12 (Figure 1 A). It seems that
ligand 6 has no effect on helix 12. There are four nitrogen atoms
near Zn in complex 7c, after energy minimization in MMFF94
force field, we found that three coordination bonds were formed.
Ligand 7c can dock well with ERα activation conformation
(2YAT), but no reasonable orientation was found with ERα
inhibitory conformation (2OUZ). The estradiol moiety in
compound 7c binds with ERα activation conformation in the
same manner with compound 6 (Figure 1 B/C). The binding site
of ERα inhibitory conformation getting narrow near the β-sheet
and the introduction of Zn making the substitute moiety more
rigid, both of the reasons make compound 7c fail to dock with
ERα inhibitory conformation (Figure 1 D). Larger molecules
tend to receive higher free energy during modeling in autodock,
so we adopt energy-mass ratio (energy-mass ratio = 100 * free
energy / mass) to represent the binding affinity, and the result
show in Table 3. Compound 6 got an energy-mass ratio of -2.27
to 2YAT, while -2.31 to 2OUZ and 7c got -1.81 to 2YAT. It
reveals that both compound 6 and 7c can dock with ER very
well.
6
0.65 ± 0.01
0.95 ± 0.1
2.3 ± 0.5
0.88 ± 0.03
4.04 ± 0.38
0.85 ± 0.05
0.57 ± 0.15
< 0.1
7a
7b
7c
aRelative binding affinity (RBA) values were determined by
competitive binding assay based on fluorescence polarization
(Estradiol = 100%). bMean of three experiments ± range.
From the Table 1 we could see that all synthesized complexes
still retained essential binding affinity to both ER and
ERexcept 7c. The conjugation of metal ions into the neutral
ligand 6 indeed influences their RBA, but the effect can be either
positive or negative. Additionally, among the complexes 7a-c, 7b
(Ni) showed the highest RBA to ER, but 7a (Pd) had the best
RBA to ER. This binding preference may be related to the
distinct characteristics of the three transition metal ions.
Compared to the neutral free ligand 6, the binding affinity of
7a-c for ER increased (the highest is 4 fold), while the binding
affinity of 7a-c for ERall decreased. Some works reported that
the binding affinity of a cationic complex was very likely to drop
to some degree when compared to its neutral metal-free ligand[10a]
But Jackson et al reported some estrogen derived metal
complexes showed higher ER binding affinity than the neutral
.
Table 3. Energy-mass ratio estradiol and compound 6a
metal-free ligands[12a]
.
2YAT
-3.99a
-2.27
-1.81
2OUZ
-3.48
-2.31
--
The transcriptional activity of these compounds was tested by
a Luciferase reporter gene assays in human embryonic kidney
293T (HEK-293T) cells (details shown in Supporting
Information). The transcriptional activities were summarized in
Table 3.
ES
6
7c
aenergy-mass ratio = 100*free energy/mass.
From the Table 2 we could conclude that in HEK-293T cells,
all synthesized compounds were agonists on ERCompound 7a
and 7c showed greater agonist activity than the neutral free
ligand 6. It was clear that this series of compounds could not or
just have low efficacy acting as antagonist on ER.
Table 2. Transcription Activation of compounds 6 and 7a-c
through ERa
a
Cells were transfected with full-length human ER and an
estrogen responsive reporter gene. Compounds were tested at 10-5
to 10-11 M alone (as agonists) or in the presence of 10-8
M
Figure 1. The binding model of compound 6 and 7c with 2YAT
and 2OUZ. A) The binding model of compound 6 with2OUZ; B)
His 524, Glu 353 and Arg 394 can form hydrogen bonds with 7c
(the same with compound 6, data not shown). C) The binding
model of compound 7c with 2YAT. D) Conformation difference
estradiol (as antagonists). In all cases, 10-8 M estradiol alone was
set as 100% activation ability.
To further investigate the structure-binding affinity
correlations and how those ligands oriented, we performed
molecular docking by autodock software. Because of lacking of

Pais, A.; Gunanathan, C.; Milstein, D.; Degani, H.; Sussman, J.L. J Med
Chem. 2011, 54, 3575.
13. (a) Alemn, J.; Parra, A; Jiang, H.; Jørgensen, K.A. Chem Eur J. 2011,
17, 6890; (b) Ian Storer, R.; Aciro, C.; Jones, L.H. Chem Soc Rev. 2011,
40, 2330.
of 2OUZ (green) and 2YAT (yellow), the loop between helix 8
and β-sheet make 7c failed to dock with 2OUZ.
In this study, we have described the synthesis and biological
evaluation of a series of estradiol-derived metal complexes
containing an unique squaramide moiety. Three metal ions in the
first and second row of transition metal have been incorporated
into the neutral ligand. All the designed complexes retain low but
effective binding affinity to estrogen receptors, and in
transcription assays, all the compounds are agonists on ERα.
Molecular modeling studies suggest a structural basis for the
agonist activity of these compounds.
14. Lebwohl, D.; Canetta, R. Eur J Cancer 1998, 34, 1522.
15. (a) Sun, Y.Y.; Yin, Runting, Gou, S.H.; Zhao, J. J Inorg Biochem. 2012,
55, 68; (b) Sun, Y.Y.; Liu, F.; Gou, S.H.; Cheng, L.; Fang, L.; Yin,
Runting. Eur J Med Chem. 2012, 55, 297; (c) Said S. Al-Jaroudi,
Mohammed Fettouhi, Mohammed I.M. Wazeer, Anvarhusein A. Isab,
Saleh Altuwaijri. Polyhedron 2013, 50, 434.
16. (a) Salam Al-Baker, Shaikh Shamsuddin, Zahid H. Siddik, Abdul R.
Khokhar. J Med Chem. 1997, 40, 112; (b) Chun-Wing Yu, Kay K. W.
Li, Siu-Kwong Pang, Steve C. F. Au-Yeung, Yee-Ping Ho. Bioorg Med
Chem Lett. 2006, 16, 1686.
17. (a) Zhou, H.B.; Zhang, J.; Lu, S.M.; Xie, R.G.; Zhou, Z.Y.; Choi,
M.C.K.; Chan, A.S.C.; Yang, T.K. Tetrahedron 2001, 57, 9325; (b)
Dahan, A.; Ashkenazi, T.; Kuznetsov, V.; Makievski, S.; Drug, E.;
Fadeev, L.; Bramson, M.; Schokoroy, S.; Rozenshine-Kemelmakher, E.;
Gozin, M. J Org Chem. 2007, 72, 2289.
18. Kim, S.H.; Katzenellenbogen, J.A. Angew Chem Int Ed. 2006, 45, 7243.
19. Nettles, K.W.; Bruning, J.B.; Gil, G.; Nowak, J.; Sharma, S.K.; Hahm,
J.B.; Kulp, K.; Hochberg, R.B.; Zhou, H.B.; Katzenellenbogen, J.A.;
Katzenellenbogen, B.S.; Kim, Y.C.; Joachmiak, A.; Greene, G.L. Nat
Chem Biol. 2008, 4, 241.
Acknowledgments
We are grateful to the NSFC (81172935, 91017005,
30970914), the Program for New Century Excellent Talents in
University (NCET-10-0625), Key Project of Ministry of
Education (313040), the Scientific and Technological innovative
Research Team of Wuhan (2013070204020048), and the
Fundamental Research Funds for the Central Universities for
support of this research.
20. Experimental: Melting points were obtained on X-4 melting point
apparatus (Beijing TECH Instruments, Co., Ltd.) and are uncorrected.IR
spectra were measured on a Nicolet 470FT-IR spectrophotometer in
the range of 400–4000 cm-1. 1H NMR and 13C NMR spectra were
obtained on Bruker Biospin AV400 (400 MHz) instrument. The
chemical shifts are reported in ppm and are referenced to either TMS or
the solvent. MS data were obtained on IonSpec 4.7 Tesla FTMS.
Compound 6: A solution of compound 5 (97.2 mg, 0.195 mmol),
compound 1 (53.0 mg, 0.243 mmol) and Et3N (0.2 mL) in CH2Cl2 (10
mL) was stirred at room temperature overnight. After completion, the
reaction was concentrated under reduced pressure and purified by flash
column chromatography to give compound 6 as a white solid (124.2 mg,
95%). m.p: 158-162 ℃. IR(KBr) νmax 3387, 2921, 2852, 1798, 1678,
1606, 1578, 1535, 1456, 1262, 1104 CM-1. 1H NMR (400 MHz,
Acetone-d6) δ 10.14 (s, 1H), 8.88 (t, J = 9.5 Hz, 1H), 8.16 (d, J = 14.7
Hz, 1H), 7.83–7.70 (m, 1H), 7.30 (dd, J = 11.3, 7.4 Hz, 1H), 7.23 (d, J =
7.7 Hz, 2H), 7.19–7.13 (m, 1H), 7.13–7.05 (m, 2H), 7.00 (dd, J = 9.7,
5.7 Hz, 1H), 6.64 (dd, J = 8.5, 5.5 Hz, 1H), 6.59–6.50 (m, 1H), 6.05 (s,
1H), 5.42 (s, 1H), 3.94 (dd, J = 19.9, 9.1 Hz, 2H), 3.77 (t, J = 13.3 Hz,
1H), 2.92–2.34 (m, 6H), 2.22 (ddd, J = 30.4, 19.0, 13.6 Hz, 5H), 2.10
(d, J = 6.8 Hz, 1H), 2.03–1.81 (m, 3H), 1.75 (s, 3H), 1.65 (dd, J = 13.2,
8.8 Hz, 1H), 1.59–1.22 (m, 8H), 1.17 (d, J = 9.5 Hz, 2H), 0.90 (s, 3H);
13C NMR (100 MHz, Acetone-d6) δ 186.51, 183.23, 172.07, 162.71,
156.21, 153.10, 148.33, 140.42, 139.80, 138.39, 132.02, 128.75, 126.76,
118.73, 116.14, 113.59, 113.13, 98.87, 96.24, 81.58, 80.05, 61.18,
60.65, 58.34, 57.40, 50.53, 45.75, 42.96, 41.79, 40.97, 40.60, 40.06,
39.53, 38.08, 34.26, 31.93, 30.69, 28.26, 27.85, 27.69, 26.52, 25.43,
25.35, 23.98, 23.14, 14.56. MS (ESI) m/z: 670 (M)+. HRMS calcd for
C42H46N4O4 [M] + 670.35191, found 670.35211.
References and notes
1. (a) Deroo, B.J.; Korach, K.S. J Clin Invest. 2006, 116, 561; (b) Heldring,
N.; Pike, A.; Andersson, S.; Matthews, J.; Cheng, G.; Hartman, J.;
Tujague, M.; Strom, A.; Treuter, E.; Warner, M.; Gustafsson, J. A.
Physiol Rev. 2007, 87, 905.
2. (a) Katzenellenbogen, B.S.; Katzenellenbogen, J.A. Chem Biol. 1996, 3,
529–536; (b) Kuiper, G.G.J.M.; Carlquist, M.; Gustafson, J.A. Sci Med.
1998, 5, 36.
3. Wang, P.H. Taiwan J Obstet Gynecol. 2005, 44, 16.
4. Howell, S.J.; Stephen, R.D.; Johnston, A.H. Best Pract Res Cl En. 2004,
18, 47.
5. Yager, J.D.; Davidson, N.E. N Engl J Med. 2006, 354, 270.
6. (a) Wang, P.H.; Cheng, M.H.; Chao, H.T.; Chao, K.C. Taiwan J Obstet
Gynecol. 2007, 46, 121; (b) Lee, W.L.; Chao, H.T.; Cheng, M.H.; Wang,
P.H. Maturitas 2008, 60, 92.
7. (a) Yam, V.W.W.; Lo, K.K.W. Coord Chem Rev. 1998, 184,157; (b)
Reichert, D.E.; Lewis, J.S.; Anderson, C.J. Coord Chem Rev. 1999, 184,
3; (c) Thunus, L.; Lejeune, R. Coord Chem Rev. 1999, 184, 125; (d)
Sava, G.; Gagliardi, R.; Bergam, A.; Alessio, E.; Mestroni, G.
Anticancer Res. 1999, 19, 969. (e) Guo, Z. J.; Sadler, P. J. Adv Inorg
Chem. 2000, 49, 183; (f) Verhaar-Langereis, M. J.; Zonnenberg, B. A.;
de Klerk, J.M.H.; Blijham, G.H. Cancer Treat Rev. 2000, 26, 3; (g)
Zhang, C.X.; Lippard, S.J. Curr Opin Chem. Biol. 2003, 7, 481; (h)
Rafique, S.; Idrees, M.; Nasim, A.; Akbar, H.; Athar, A. Biotechnol Mol
Biol Rev. 2010, 5, 38.
8. Biersack, B. and Schobert, R. Curr Med Chem. 2009, 16, 2324.
9. (a) Lee, C.Y.; Hanson, R. N. Tetrahedron 2000, 56, 1623; (b) Jackson,
A.; Davis, J.; Pither, R.J.; Rodger, A.; Hannon M.J. Inorg Chem. 2001,
40, 3964; (c) Bideau, F.L.; Salmain, M.; Top, S.; Jaouen, G. Chem Eur
J. 2001, 7, 2289.
10. (a) Amouri, H. I.; Vessières, A.; Vichard, D.; Top, S.; Gruselle, M.;
Jaouen, G. J Med Chem. 1992, 35, 3130; (b) Top, S.; El Hafa, H.;
Vessières, A.; Quivy, J.; Vaissermann, J.; Hughes, D. W.; McGlinchey,
M. J.; Mornon, J.P.; Thoreau, E.; Jaouen, G. J Am Chem Soc. 1995, 117,
8372.
11. (a) Lo, K.-W., Zhang, K., Chung, C.-K.; Kwok, K. Chem Eur J. 2007,
13, 7110; (b) Lo, K.K.; Lee, T.K.; Lau, J.S.; Poon, W.L.; Cheng, S.H.
Inorg Chem. 2008, 47, 200; (c) Huang, L.L.; Zhu, H.; Zhang, Y.Q.; Xu,
X.P.; Cui, W.; Yang G.; Shen, Y.M. Steroids 2010, 75, 905; (d) Hanson,
R.N.; Kirss, R.; McCaskill, E.; Hua, E.; Tongcharoensirikul, P.;
Olmsted, S.L.; Labaree, D.; Hochberg, R.B. Bioorg Med Chem Lett.
2011, 22, 1670.
General Procedure for Synthesis of 7a-c:
A solution of [Pd(MeCN)2Cl2] (44.1 mg, 0.170 mmol) in anhydrous
CH2Cl2 (10 mL) was added dropwise with stirring to a solution of
compound 6 (110.0 mg, 0.164 mmol) in anhydrous CH2Cl2 (10 mL).
After completion, the solution was concentrated, filtered and washed
with CH2Cl2 to give compound 7a (67.9 mg, 51%). m.p: 260-265 ℃. IR
(KBr) νmax 3369, 2927, 2851, 1728, 1611, 1537, 1451, 1410, 1277, 1106
1
cm-1. H NMR (400 MHz, DMSO-d6) δ 10.14 (s, 1H), 8.88 (t, J = 9.5
Hz, 1H), 8.16 (d, J = 14.7 Hz, 1H), 7.83–7.70 (m, 1H), 7.30 (dd, J =
11.3, 7.4 Hz, 1H), 7.23 (d, J = 7.7 Hz, 2H), 7.19–7.13 (m, 1H), 7.13–
7.05 (m, 2H), 7.00 (dd, J = 9.7, 5.7 Hz, 1H), 6.64 (dd, J = 8.5, 5.5 Hz,
1H), 6.59–6.50 (m, 1H), 6.05 (s, 1H), 5.42 (s, 1H), 3.94 (dd, J = 19.9,
9.1 Hz, 2H), 3.77 (t, J = 13.3 Hz, 1H), 2.92–2.34 (m, 6H), 2.22 (ddd, J
= 30.4, 19.0, 13.6 Hz, 5H), 2.10 (d, J = 6.8 Hz, 1H), 2.03–1.81 (m, 3H),
1.75 (s, 3H), 1.65 (dd, J = 13.2, 8.8 Hz, 1H), 1.59–1.22 (m, 8H), 1.17
(d, J = 9.5 Hz, 2H), 0.90 (s, 3H). HRMS Calcd for C42H46Cl2N4O4Pd
[M] + 846.1913, found 846.19111.
12. (a) Jackson, A.; Davis, J.; Pither, R. J.; Rodger, A.; Hannon, M.J. Inorg
Chem. 2001, 40, 3964; (b) Arterburn, J.B.; Corona, C.; Venkateswara
Rao, K.; Carlson, K.E.; Katzenellenbogen, J.A. J Org Chem. 2003, 68,
7063; (c) Hannon, M.J.; Green, P.S.; Fisher, D.M.; Derrick, P.J.; Beck,
J.L.; Watt, S.J.; Ralph, S.F.; Sheil, M.M.; Barker, P.R.; Alcock, N.W.;
Price, R.J.; Sanders, K.J.; Pither, R.; Davis, J.; Rodger, A. Chem Eur J.
2006, 12, 8000; (d) Li, M.J.; Greenblatt, H.M.; Dym, O.; Albeck, S.;
21. Zheng, Y.; Wang, C.; Li, C.; Qiao, J.; Zhang, F.; Huang, M.; Ren, W.;
Dong, C.; Huang, J.; Zhou, H.B. Org Biomol Chem. 2012, 10, 9689.
22. Molecular Operating Environment (MOE), Molecular Operating
Environment 2010.10, Chemical Computing Group Inc., 1010
Sherbooke St. West, Suite #910, Montreal, QC, Canada, H3A 2R7,
2010.

23. Shiau, A.K.; Barstad, D.; Radek, J.T.; Meyers, M.J.; Nettles, K.W.;
K.W.; Katzenellenbogen, B.S.; Katzenellenbogen, J.A.; Agard, D.A.;
Greene, G.L. Nat Struct Biol. 2002, 9, 359.
21 Å in X, Y, Z dimension respectively (a grid spacing of 0.375 Å),
which encompassed the whole active site, was used throughout
docking. On the basis of the Lamarckian genetic algorithm (LGA), 100
runs were performed for each ligand with 500 individuals in the
population. The maximum numbers of energy evaluations and of
generations were 2.5e7 and 2.7e4, respectively. Other parameters were
set as default. The resulting docking solutions were subsequently
clustered with a root-mean square deviation (rmsd) tolerance of 2.0 Å
and were ranked by binding energy values.
24. Molecular-docking: Estradiol and compound 6 were docked into the
into the three-dimensional structure of ERα/β-LBD with the AutoDock
software package (version 4.2)[25]. Crystallographic coordinates of
small molecules were created by Biochemoffice. The crystal structures
of ERα/β-LBD (PDB code: 2YAT, 2OUZ) were obtained from the
Protein Data Bank (PDB) and all water molecules were removed.
Preparations of all ligands and the protein were performed with
AutoDockTools (ADT). A docking cube with the edge of 22.5 Å, 24 Å,
25. (a) Audie, J. Biophys Chem. 2009, 139, 84. (b) Huey, R.; Morris, G.M.;
G.M.; Olson, A.J.; Goodsell, D.S. J Comput Chem. 2007, 28, 1145.

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Design, Synthesis and Biological Evaluation of Novel
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Estrogen-derived Steroidal Metal Complexes
Xinlong Zhang,a Ziqing Zuo,a Juan Tang,a Kai Wang,a Caihua Wang,b Weiyan Chen,a
Changhao Li,b Wen Xu,b Xiaolin Xiong,a Kangxiang Yuntai,a Jian Huang,b Xiaoli Lan,c Hai-Bing Zhoua*