Synthesis and vasodilative activity of tanshinone IIA derivatives

Article abstract of DOI:10.1016/j.bmcl.2010.06.076

A series of 2,2′-(substituted methylene)bis-(1,6,6-trimethyl-6,7,8,9- tetrahydrophenanthro[1,2-b]furan-10,11-dione) derivatives were synthesized by the reaction of tanshinone IIA (D₁) and aromatic aldehyde in the presence of p-TsOH. Bromination derivative of D₁ and hydrolysis product of cryptotanshinone (D₂) were also prepared in this work. Vasodilation activity in vitro of them was valuated on the contractile response of vascular thoracic aorta smooth muscle from Wistar rats for the first time. Most of them exhibited a concentration-dependent inhibition on the contractile response of norepinephrine.

Full text of DOI:10.1016/j.bmcl.2010.06.076

Bioorganic & Medicinal Chemistry Letters 20 (2010) 4892–4894
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis and vasodilative activity of tanshinone IIA derivatives q
Yue-Feng Bi a,b, Hai-Wei Xu a,b,c, Xiao-Qing Liu a, Xiao-Juan Zhang a, Zhen-Ji Wang a, Hong-Min Liu a,b,
*
a School of Pharmaceutical Science, Zhengzhou University, Ke Xue Da Dao 100, Zhengzhou 450001, PR China
b New Drug Research & Development Center, Zhengzhou University, Zhengzhou 450001, PR China
c Furen Science and Technology Pharmaceutical Weiwu Road, Zhengzhou 450003, PR China
a r t i c l e i n f o
a b s t r a c t
A series of 2,20-(substituted methylene)bis-(1,6,6-trimethyl-6,7,8,9-tetrahydrophenanthro[1,2-b]furan-
10,11-dione) derivatives were synthesized by the reaction of tanshinone IIA (D1) and aromatic aldehyde
in the presence of p-TsOH. Bromination derivative of D1 and hydrolysis product of cryptotanshinone (D2)
were also prepared in this work. Vasodilation activity in vitro of them was valuated on the contractile
response of vascular thoracic aorta smooth muscle from Wistar rats for the first time. Most of them
exhibited a concentration-dependent inhibition on the contractile response of norepinephrine.
Ó 2010 Elsevier Ltd. All rights reserved.
Article history:
Received 23 February 2010
Revised 9 June 2010
Accepted 14 June 2010
Available online 17 June 2010
Keywords:
Synthesis
Vasodilative activity
Tanshinone
Salvia miltiorrhiza (SM) has been widely used in the treatment
of cardiovascular and coronary artery disease in traditional Chinese
medicine practice.1–4 It has been reported that the relaxation by
SM in rat aorta ring is endothelium dependent and is possibly med-
iated by the nitric oxide–guanylyl cyclase pathway.5–7 Tanshinone
IIA (D1), which is the major bioactive lipophilic ingredient of SM,
shows anti-cancer, anti-bacterial, cardiovascular system activities
and could reduce inflammatory reaction of cerebral ischemia
tissue.8–11 Cryptotanshinone (D2), another bioactive natural
ingredient in the SM, has been fully proved anti-inflammatory
and anti-oxidative (Fig. 1). But there were few reports about the
vasodilation activity of vascular thoracic aorta smooth muscle of
tanshinones and their derivatives.
ran ring was opened in the reaction. However, hydrolysis reaction
of D1 was failed.
2,20-(Substituted methylene)bis-(1,6,6-trimethyl-6,7,8,9-tetra-
hydrophenanthro[1,2-b]furan-10,11-dione) derivatives (2–13)
were synthesized by the reactions of D1 and aldehydes at the pres-
O
O
O
O
O
O
In the study, tanshinone derivatives were synthesized by the
reactions of D1 with some aromatic aldehydes.12 Bromination
derivative of D1 and hydrolysis product of cryptotanshinone (D2)
were also prepared. Vasodilation activity of them was investigated
in vitro and compounds 1, 2, 10 and 11 reveal remarkable vasodi-
lation activity.
D1
D2
Figure 1. Structures of tanshinone IIA (D1) and cryptotanshinone (D2).
Compound 1 was synthesized by the hydrolysis of D2 in the
presence of sodium hydroxide (Scheme 1). In the 1H NMR spec-
tra,13 the shift of two hydrogen protons in the C1 of the dihydrofu-
O
0
OH
ran ring of compound 1 were upfield at dH 3.95 and dH 3.84 in
O
O
comparison to that of D2 at dH 4.98 and dH 4.43. In the 13C NMR
OH
0
spectra, the shift of C1 in compound 1 at d 65.4, was upfield in
OH-
1'
O
O
comparison to that of D2 at d 81. It was concluded that dihydrofu-
q
D2
Supported by the National Nature Science Foundation of China.
1
* Corresponding author. Tel./fax: +86 371 67781739.
E-mail address: liuhm@zzu.edu.cn (H.-M. Liu).
Scheme 1. Reagents and conditions: 2 mol/l NaOH, anhydrous CH3CH2OH, rt 12 h.
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.06.076

Y.-F. Bi et al. / Bioorg. Med. Chem. Lett. 20 (2010) 4892–4894
4893
Table 1
ence of p-TsOH (Scheme 2). In order to avoid oxidation of protocat-
echualdehyde, the reaction carried out under the nitrogen protec-
tion. In the reaction, the solvent, chloroform was purified by the
process of washing with water to remove EtOH, followed by dry-
ing, refluxing and distilling, which could improved the reaction
yield. In addition, 2-bromo-1,6,6-trimethyl-6,7,8,9-tetrahydro-
phenanthro[1,2-b]furan-10,11-dione (14) was prepared by the
reaction of D1 and bromine liquid in the carbon tetrachloride
(Scheme 2).
The relaxant effects of norepinephrine (10ꢁ6 mol/l) induced contraction in rat
thoracic aorta (X SEM) (n, the number of cases used)
Compd
% Inhibition of norepinephrine contraction in rat thoracic aorta
10ꢁ4
M
n
1
2
3
4
5
6
7
8
9
10
11
12
13
14
D1
59.18 9.09
42.78 6.14
10.31 3.73
15.22 4.35
1.00 1.00
5
6
5
3
3
6
3
6
3
3
3
6
4
9
6
Vasodilation activity for the synthesized tanshinones deriva-
tives was investigated in vitro using thoracic aortic rings of male
10.98 6.21
2.95 2.22
18.84 5.71
11.37 0.78
54.98 14.20
56.04 15.53
ꢁ0.86 7.63
ꢁ29.17 7.9
4.24 2.18
O
O
O
O
Br
O
O
ii
2.92 1.61
D
14
1
Wistar rats pre-contracted with norepinephrine bitartrate
(1 ꢀ 10ꢁ6 mM) according to the known standard procedure.14,15
The result was presented in terms of percentage of the maximal
control norepinephrine-induced responses. Most of the com-
pounds showed a concentration-dependent inhibition on the con-
tractile response of norepinephrine (Fig. 2, Table 1). Especially, 1, 2,
10 and 11 (IC50, 0.48, 0.13, 0.2 and 0.26 mM, respectively) were
exhibited better activity than that of D1.16
i
O
Ar
O
O
O
O
O
The structure–activity relationship showed that meta-substi-
tuted derivatives greatly affect the activity than para-substituted
derivatives. The methoxyl-substituting group in the meta position
of aromatic aldehydes, presented better pharmacological vasodila-
tion properties than that of nitro substitution derivative (Table 1).
The bioactivity of two methoxyl-substituting derivatives in the
meta position of 10 was better than that of monomethoxyl substi-
tution derivative. In addition, chloro-substituting group in the meta
position of aromatic aldehydes 11 produced far better activity than
that of the ortho position and para position. It was interesting that
chloro-substituting derivative in the ortho position of 13 presented
obvious vasoconstriction responses. The basic hydrolysis product 1
of D2 exhibited good bioactivity with IC50 of 0.48 mM.
In summary, a series of tanshinone IIA derivatives have been
synthesized and vasodilation activity in vitro of them was valuated
on the contractile response of vascular thoracic aorta smooth mus-
cle from Wistar rats. The results revealed that the synthetic prod-
ucts exhibited good activity. It is valuable to develop potent
vasodilation activity tanshinone IIA derivatives. Interactions of dif-
ferent substituent groups of aromatic aldehydes for pharmacolog-
ical vasodilation bioactivity are currently underway, which will be
reported in due course.
2-13
Comp.
Ar
Comp.
Ar
OH
OCH3
2
3
4
8
NO2
NO2
O
9
S
CH3
OCH3
OCH3
OCH3
OH
10
Cl
Cl
5
11
12
13
612
712
OH
OH
OCH3
Cl
Scheme 2. Reagents and conditions: (i) 1 equiv aromatic aldehyde, p-TsOH,
anhydrous CHCl3, 50–60 °C, 12 h; (ii) 1 equiv Br2, CCl4, rt 20 min.
Compound 2
Compound 1
120
100
80
60
40
20
0
120
100
80
60
40
20
0
Acknowledgment
0
1
2
0
0.05
0.1
0.15
0.2
We gratefully acknowledge support from the National Nature
Science Foundation of China.
Concentration (mM)
Concentration (mM)
Compound 10
Compound 11
References and notes
120
100
80
60
40
20
0
120
100
80
60
40
20
0
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0
0.1 0.2 0.3 0.4 0.5
Concentration (mM)
0
0.1
0.2
0.3
0.4
Concentration (mM)
Figure 2. Influence of synthesized compounds on contracture induced by norepi-
nephrine bitartrate in thoracic aortic rings of rats.

4894
Y.-F. Bi et al. / Bioorg. Med. Chem. Lett. 20 (2010) 4892–4894
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and dislocated in the cervical. Then thoracic aortas were immediately
dislodged from Wistar rats and placed in a Krebs–Henseleit solution which
was composed of (in mM): NaCl, 118.0; KCl, 4.7; NaHCO3, 25.0; CaCl2, 2.5;
NaH2PO4, 1.2; MgSO4, 1.2; EDTA, 0.016; glucose, 12 and was saturated in a gas
of 95% O2/5% CO2 at 4 °C. After surface tissues were removed, the aortas were
cut in 2–3 mm ring and fastened in 10 mL organ baths, which maintained at
37 °C in a gas of 95% O2/5% CO2. The preparations were allowed to balance for
2 h under 1.5 g basal tensions and the Krebs–Henseleit solution in the organ
baths was changed every 20 min.
The integrality of aorta’s endothelium was checked before synthesized
compounds were added to the organ baths. If the percentage of relaxation of
pre-contracted aorta by norepinephrine bitartrate (1 ꢀ 10ꢁ6 mmol) by
acetylcholine (1 ꢀ 10ꢁ5 mmol) was greater than 80%, endothelium was
deemed to be intact. Removal of functional endothelium was confirmed by
the lack of relaxation (<10%) in the presence of acetylcholine. The tested
compounds were dissolved in dimethylsulfoxide (DMSO) as stock solution
(50 mg/mL). Contrast tests were performed in the presence of DMSO alone, at
the same concentrations as those used with the synthesized compounds, in
order to check contractile response of aorta rings was not affected. All the
results were performed as mean the standard error of the mean (SEM). Dose–
response curves were used to exhibit different effects of compounds.
Differences between different concentrations were considered statistically
significant when paired Student’s t-test was under the condition of P <0.05.
13. All newly synthesized compounds have adequate spectral data, for example,
compound 11, IR (KBr, cmꢁ1): 3439, 2927, 2856, 1673, 1581, 1467, 1381, 1274,
1199. 1H NMR (400 MHz, CDC13, TMS): d 7.62 (d, 2H, J = 8.2 Hz, H-5,50), 7.47 (d,
2H, J = 8.1 Hz, H-4,40), 7.16–7.32 (m, 4 H, H-200,400,500,600), 5.61 (s, 1H, –CH), 3.18
(t, 4H, J = 6.2 Hz, H-9,90), 2.22 (s, 6 H, –CH3 ꢀ 2), 1.77–1.80 (m, 4 H, H-8,80),
1.64–1.66 (m, 4H, H-7,70), 1.30 (s, 12 H, –CH3 ꢀ 4). 13C NMR (400 MHz, CDC13
,
TMS): d 183.27 (C-10, C-100), 175.67 (C-11, C-110), 160.70 (C-3a, C-30a0), 150.40
(C-5a, C-50a0), 149.45 (C-2, C-20), 144.68 (C-9a, C-90a0), 139.03 (C-300), 134.88 (C-
100), 133.54 (C-5, C-50), 130.18 (C-200), 128.08 (C-400, C-500), 127.00 (C-3b, C-30b0),
126.48 (C-9b, C-90b0), 126.12 (C-600), 120.48 (C-4, C-40), 120.23 (C-11a, C-110a0),
117.98 (C-1, C-10), 40.13 (–CH), 37.74 (C-7, C-70), 34.67 (C-6, C-60), 31.83 (–
CH3 ꢀ 4), 29.70 (C-9, C-90), 19.06 (C-8, C-80), 8.86 (–CH3 ꢀ 2). EIMS: 711.38
[M+H]+.
14. Silva, A. G.; Zapata-Sudo, G.; Kummerle, A. E.; Fraga, C. A. M.; Barreiro, E. J.;
Sudo, R. T. Bioorg. Med. Chem. 2005, 13, 3431.
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Sudo, G. Eur. J. Pharmacol. 2006, 530, 117.
16. Screening of vasodilatiory activity synthesized compounds was carried out on
the thoracic aortic rings of male Wistar rats (200–300 g), which were stunned