Design, synthesis and molecular docking studies of sinomenine derivatives

Article abstract of DOI:10.1016/j.bmcl.2012.07.087

In order to search for drugs with excellent anti-inflammatory activities, a series of novel sinomenine derivatives were designed, synthesized, and evaluated for their inhibition activities against NF-κB activation induced by lipopolysaccharide (LPS). Compared with the natural parent sinomenine, compounds 2a-w showed higher activity, while compounds 1a-o showed similar activity against NF-κB. Moreover, a molecular model for the binding between compound 2v and the active site of p50 was provided on the basis of the computational docking results.

Full text of DOI:10.1016/j.bmcl.2012.07.087

Bioorganic & Medicinal Chemistry Letters 22 (2012) 5849–5852
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Design, synthesis and molecular docking studies of sinomenine derivatives
Xiaoyun Chai a, , Zhongjun Guan a,c, , Shichong Yu a, Qingjie Zhao a, Honggang Hu a, Yan Zou a, Xia Tao b,
,
⇑
Qiuye Wu a,
⇑
a Department of Organic Chemistry, School of Pharmacy, Second Military Medical University, No. 325 Guohe Road, Shanghai 200433, China
b Department of Pharmacy, Changzheng Hospital, Second Military Medical University, No. 415 Fengyang Road, Shanghai 200003, China
c Department of Pharmacognosy, School of Pharmacy, Fudan University, No. 826 Zhangheng Road, Shanghai 201203, China
a r t i c l e i n f o
a b s t r a c t
Article history:
In order to search for drugs with excellent anti-inflammatory activities, a series of novel sinomenine
derivatives were designed, synthesized, and evaluated for their inhibition activities against NF- B activa-
tion induced by lipopolysaccharide (LPS). Compared with the natural parent sinomenine, compounds
2a–w showed higher activity, while compounds 1a–o showed similar activity against NF- B. Moreover,
a molecular model for the binding between compound 2v and the active site of p50 was provided on the
basis of the computational docking results.
Received 10 May 2012
Revised 14 July 2012
Accepted 24 July 2012
Available online 1 August 2012
j
j
Keywords:
Sinomenine
Design
Ó 2012 Elsevier Ltd. All rights reserved.
Synthesis
NF-jB
Molecular docking
Rheumatoid arthritis (RA) is a systemic inflammatory disease
characterized by chronic and erosive synovitis that involves periph-
eral joints.1 Three major classes of drugs used for RA are currently in
clinical use: nonsteroidal anti-inflammatory drugs (NSAIDs) (such
as indomethacin), antirheumatic drugs (such as methotrexate),
and corticosteroids (such as dexamethasone) (Fig. 1). However,
the long-term use of anti-inflammatory drugs has led to serious
health hazards, such as interstitial pneumonitis, pulmonary fibrosis,
nephritis, and neurocognitive impairment.2 Thus, these have
emphasized the urgent need for new, effective, and safe anti-inflam-
matory agents.
For many decades, numerous bioactive products isolated from
various natural resources have influenced modern drug discovery
across the therapeutic spectrum.3 Therefore, great efforts have
been made to discover lead compound from natural product in
an attempt to obtain new anti-inflammatory drugs.
an active role in inflammatory responses. The family of NF-jB tran-
scription factors is intimately involved in the regulation of expres-
sion of numerous genes in the setting of the inflammatory
response. In mammals, the NF-
RelA (p65), RelB, c-Rel, NF- B1 (p50 and its precursor p105), and
NF- B2 (p52 and its precursor p100). They form a variety of homo-
dimers and heterodimers. The most prevalent activated form is the
heterodimer p65–p50. Normally, NF- B is present in the cyto-
plasm of almost all mammalians cells in an inactive form (I Ba-
p50-p65) associated with the inhibitory B proteins (I
B).7–9
jB family consists of five members:
j
j
j
j
j
j
However, few applications have been developed due to sinom-
enine’s unsatisfactory immunomodulating activity and short bio-
logical half-life.4,10,11 After comprehensive analysis of the natural
structure of sinomenine and its previous modifications, we intro-
duced nitrogen-containing heterocycles to sinomenine, which are
frequently employed in modern drug design. 1, 2, 3-Triazole pos-
sess favorable properties for medicinal chemistry such as a moder-
ate dipole character, hydrogen bonding capability, rigidity and
stability under in vivo conditions.12 A series of sinomenine deriva-
tives (Fig. 3) have been designed and synthesized by introducing
substituted 1, 2, 3-triazole group (1a–o) or substituted benzyl
group (2a–w) into skeleton of sinomenine to test their in vitro inhi-
Sinomenine (7, 8-didehydro-4-hydroxy-3, 7-dimethoxy-17-
methylmorphinan-6-one) (Fig. 2), a naturally abundant alkaloid
isolated from the traditional chinese medicinal plant Sinomenium
acutum, has been demonstrated to have variety of pharmacological
effects, including anti-inflammation, immunosuppression, and
anti-angiogenesis.4–6 Pharmacology reveals that sinomenine de-
crease the mRNA expression of TNF-
a
by inhibiting the Nuclear
bition activities against NF-jB activation induced by LPS.
Factor-
j
B (NF-
j
B) binding activity.4 NF-kB has been found to play
The synthetic route of the target compounds 1a–o and 2a–w
was outlined in Scheme 1. Compound 4 was synthesized by the
reaction of sinomenine (3) with sodium hydroxide in CH3CN at
room temperature. The target compounds 1a–o were synthesized
in good yields by reacting compound 4 with substituted benzyl
bromide in CH3CN at room temperature. Compound 5 was synthe-
⇑
Corresponding authors. Tel./fax: +86 21 81871225.
E-mail addresses: huhonggang_fox@msn.com (X. Tao), wuqy6439@sohu.com
(Q. Wu).
contributed equally to this work.
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.07.087

5850
X. Chai et al. / Bioorg. Med. Chem. Lett. 22 (2012) 5849–5852
Figure 1. Agents used for RA in clinical therapy
The control group was measured without stimulated by LPS
(with the relative NF- B activity (NF- B/TK, fold): 1.18 0.22).
The LPS group was defined as the stimulated group (with the rela-
tive NF- B activity (NF- B/TK, fold): 5.18 0.98). The inhibition val-
ues indicate that almost all the sinomenine derivatives could more
effectively inhibit the NF- B activation induced by LPS. Especially,
compound 2c, 2m, and 2v exhibited excellent activities (respec-
tively with the relative NF- activity (NF- B/TK, fold):
j
j
j
j
j
jB
j
1.98 0.12, 1.96 0.58 and 1.80 0.17). Compared with the natural
parent sinomenine, compounds 2a–w showed higher activities
Figure 2. Structure of the sinomenine
while compounds 1a–o showed similar activity against NF-jB.
The high activity data of compounds 2a–w suggests that the strat-
egy of embedding a rigid nitrogen-containing heterocyclic moiety
into the A-ring of sinomenine generally improves the inhibition
activity against NF-jB. The introduction of 1, 2, 3-triazole between
phenolic hydroxyl group and benzyl group is significant. It may act
sized from sinomenine (3) via reacting with propargyl bromide in
CH3CN in the presence of potassium tert-butyl alcohol. And the ti-
tle compounds (2a–w) were accomplished in the presence of NaN3
and substituted benzyl bromide, using CuSO4Á5H2O and ascorbate
sodium as catalyst in DMF, at room temperature. All the new com-
pounds (1a–o, 2a–w) described above were characterized by NMR,
LC-MS and Elemental analyses.13
as H-bond acceptors.
To explain the results, we proposed a likely binding mode for 2v
to the active site of p50 based on computational docking results
(Fig. 4). From Figure 4, we observed that the skeleton of sinome-
nine could be placed into the hydrophobic pocket formed by
Tyr57, Lys59, Glu60, His141, Ser240 and Lys241. The substituted
1, 2, 3-triazole was oriented into a hydrophobic pocket formed
by Lys144, Asp206, Leu207, Ser208, Ala242, Pro243 and Asn244.
Besides, the N-2 of 1, 2, 3-triazole heterocyclic moiety formed
hydrogen bond with His141. The oxygen atom of the carbonyl
could also form hydrogen bond with the amino group of Lys272.
In addition, heterocyclic moiety itself could generate indirect non-
bonding interactions with the amino residues.
The mis-regulation of the NF-jB signal pathway is involved in a
variety of inflammatory diseases that leads to the production of
inflammatory mediators.14 We assessed the effects of sinomenine
and sinomenine derivatives on NF-jB transcriptional activity in
LPS-stimulated RAW264.7 cells using a reporter gene assay.15
RAW264.7 cells (2 Â 105) co-transfected for 24 h with the mixture
of pGL3.5Â
jB-luciferase, and pRL-TK-Renilla-luciferase were pre-
treated with sinomenine or sinomenine derivatives (100
lM) for
30 min and then stimulated with LPS (1 g/mL) for 6 h. NF-jB
l
luciferase activities were measured using the Dual-Luciferase Re-
porter Assay System (Promega) according to the manufacturer’s
instructions. Data are normalized for transfection efficiency by
dividing firefly luciferase activity with that of Renilla luciferase.
Thirty-eight sinomenine derivatives (1a–o, 2a–w) were evalu-
A series of novel sinomenine derivatives were successfully de-
signed and synthesized. And their inhibition activities against
NF-
sinomenine, some of these derivatives showed improved activities,
while others exhibited similar activity against NF- B. Our present
results clearly showed that the introduction of substituted 1, 2, 3-
jB activation induced by LPS were evaluated. Compared with
ated for their inhibition activities against NF-jB activation induced
j
by LPS. The results of assays are summarized in Table 1.
Figure 3. All the compounds we designed and synthesized

X. Chai et al. / Bioorg. Med. Chem. Lett. 22 (2012) 5849–5852
5851
Scheme 1. Synthesis of sinomenine derivatives Conditions: (a) sodium hydroxide, CH3CN, rt, 3 h; (b) CH3CN, substituted benzyl bromide, rt, 4 h, in 77.0–84.0% yield; (c)
propargyl bromide, potassium tert-butyl alcohol, CH3CN, rt, 4 h, in 66.3% yield; (d) DMF, NaN3, substituted benzyl bromide, CuSO4 .5H2O, Vc-Na, rt, 6 h, in 87.5–93.0% yield.
Table 1
Effects of sinomenine derivatives on NF-jB transcriptional activity in LPS-stimulated RAW264.7 cells
Treatment
Relative NF-jB activity (NF-
jB/TK, fold)
Treatment
Relative NF-jB activity (NF-jB/TK, fold)
1a
1b
1c
1d
1e
1f
1g
1h
1i
4.71 1.53##
4.53 1.29##
4.22 1.18##
5.03 0.09##
4.51 1.41##
4.82 0.65##
4.91 1.76##
4.71 2.11##
5.24 0.45##
4.70 0.71##
4.18 1.18##
4.37 1.28##
5.09 0.23##
4.28 1.21##
4.85 0.31##
3.13 0.36##
3.04 0.89##
1.98 0.12##
2.39 0.20##
2.88 0.83##
2.22 1.01##
2g
2h
2i
2j
2k
2.08 0.08##
2.46 0.20##
4.19 1.07##
3.00 0.71##
2.98 0.58##
3.37 1.08##
1.96 0.58##
2.86 1.60##
3.61 0.08##
2.32 0.85##
3.17 0.40##
3.63 0.67##
3.12 0.44##
3.44 1.38##
2.74 2.18##
1.80 0.17##
3.26 2.67##
1.18 0.22
2l
2m
2n
2o
2p
2q
2r
1j
1k
1l
1m
1n
1o
2a
2b
2c
2d
2e
2f
2s
2t
2u
2v
2w
control
LPS
Sin
5.18 0.98**
4.41 1.55##
N = 3.
**
P <0.01 vs control.
P <0.01 vs LPS.
##
Figure 4. Binding mode picture of the compound 2v with the surface of p50 (The molecule is compound 2v with the highest inhibition to NF-kB transcriptional activation

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X. Chai et al. / Bioorg. Med. Chem. Lett. 22 (2012) 5849–5852
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triazole group with a proper length greatly enhanced the activity of
these title compounds against the NF- B. And the introduction of
j
the substituted benzyl group is not necessary to improve their
activities. The obtained result demonstrates that our effort which
maintains the pharmacophores, inserts the substituted 1, 2, 3-tria-
zole group into C-4 is encouraging. This observation was explain-
able by a molecular model resulting from the computational
docking simulation. This research help us discover compound 2v
to be worthy of further optimization. Further evaluations are nec-
essary to determine the activities of these title compounds in vivo
and help us to optimize these new leading compounds.
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13. Representative analytical data for compound 2v: 7,8-didehydro-4-[(1-benzyl-
1H-1, 2, 3-triazol-4-yl)methoxy]-3,7-dimethoxy-17-methyl-morphinan-6-one
(2v) Mp: 195.6–196.7 °C; Brown solid; 1H NMR (300 MHz, CDCl3): 7.81 (1H, s,
H-19), 7.27–7.41 (5H, m, Ar-H), 6.77–6.80 (2H, d, J = 8.4 Hz, H-1, H-2), 5.50–
5.59 (2H, m, H-18), 5.45 (1H, s, H-8), 5.13–5.38 (2H, d, J = 11.4 Hz, H-20), 2.36–
4.12 (2H, d, J = 15.9 Hz, H-5), 3.78 (3H, s, CH3O-3), 3.48 (3H, s, CH3O-7), 3.07–
3.11 (2H, m, H-16), 2.94–3.05 (2H, m, H-10), 2.75–2.79 (1H, m, H-9), 2.54 (3H,
s, H-17), 1.96–2.02 (1H, m, H-14), 1.84–1.92 (2H, m, H-15); 13C NMR (75 MHz,
CDCl3): 193.6, 152.2, 144.9, 144.6, 143.1, 134.4, 131.8, 130.2, 129.6, 129.1,
128.7, 128.2, 126.3, 122.5, 118.1, 115.0, 108.8, 71.6, 56.4, 55.8, 54.7, 51.1, 49.0,
46.9, 45.5, 42.4, 40.3, 35.6, 24.1; LC-MS, m/z: 501.2 (M+H)+; Anal. Calcd for
C29H32N4O4: C, 69.58; H, 6.44; N, 11.19. Found: C, 69.53; H, 6.41; N, 11.12.
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Acknowledgment
This work was supported by a grant from Science & Technology
Commission of Shanghai (Nos. 08431903003), and by Shanghai
Leading Academic Discipline Project Number: B906.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2012.07.087.
15. Qiu, L.; Ding, L.; Huang, J.; Wang, D.; Zhang, J.; Guo, B. Immunology 2009, 128,
325.
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