Synthesis and biological study of 3-butyl-1-(2,6-dichlorophenyl)-1H-[1,2,4] triazol-5(4H)-one derivatives as anti-hypertension drugs

Article abstract of DOI:10.2174/157018010789869370

A series of nitric oxide-donating derivatives of [1,2,4]triazol-5(4H)-one (9a-f and 15a-f) as a novel class of angiotensin II receptor AT1 antagonists have been designed and synthesized by coupling furoxan and nitric oxide with lead compound 1. The synthe

Full text of DOI:10.2174/157018010789869370

18
Letters in Drug Design & Discovery, 2010, 7, 18-22
Synthesis and Biological Study of 3-Butyl-1-(2,6-dichlorophenyl)-1H-[1,2,4]tria-
zol-5(4H)-one Derivatives as Anti-hypertension Drugs
Yanchun Zhang1, Jinpei Zhou*,1, Weihong Pan1, Xiaoming Wu*,1 and Shuai Wang1
1Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China
Received: July 17, 2009; Revised: September 14, 2009; Accepted: September 14, 2009
Abstract: A series of nitric oxide-donating derivatives of [1,2,4]triazol-5(4H)-one (9a-f and 15a-f) as a novel class of angiotensin
II receptor AT1 antagonists have been designed and synthesized by coupling furoxan and nitric oxide with lead compound 1. The
synthesized compounds were evaluated for their antagonism of AT1 receptor with induced contraction in the rabbit tho-
racic aortic ring and the results showed that compounds 9b, 15b and 15d exhibited potent antagonistic activity of AT1 re-
ceptor. Moreover 9b, 15b, 15d, 15e had good maximum NO release amount of this series.
Keywords: AT1 antagonist, Nitric oxide-donating, Anti-hypertension, Synthesis.
INTRODUCTION
The physiological levels of endogenous NO mediate multiple
fundamental processes in the cardiovascular system, such as dilat-
ing blood vessels, inhibiting platelet adhesion and aggregation, and
attenuating leukocyte adhesion and activation. NO donors are
pharmacologically active substances that release NO spontaneously
or through enzymatic pathways [8]. Organic nitrate and nitrite es-
ters represent a class of NO-donor agents used in cardiovascular
diseases since the 19th century. The effectiveness of treatment with
these conventional esters is limited by their therapeutic half-life,
systematic absorption with potentially adverse hemodynamic ef-
fects, and problems of drug tolerance. To overcome these limita-
tions, novel NO donors have been developed, offering selectivity, a
prolonged half-life, and a reduced incidence of drug intolerance. In
the past few years, we have witnessed the flourishing of studies on
several hybrid drugs, in which a well-known molecule with a par-
ticular pharmacological pattern has been linked to an NO-donor
group, pursuing to improve the pharmacological profile or reduce
the adverse effects [9-11]. Calderon reported that adding NO-donor
side chain to losartan may improve its antiischemic car-
dio-protective properties and antiplatelet effects [12, 13]. It was
also found that the NO-donor derivative of telmisartan may be a
potent anti-hypertensive drug for treatment of hypertension and
diabetes-related cardiovascular diseases in the clinic [14].
The renin-angiotensin system (RAS) is a complex, highly regu-
lated pathway that is integral in the regulation of blood volume,
electrolyte balance, and arterial blood pressure. The primary pur-
pose of angiotensin converting enzyme (ACE), one of the main
enzymes of RAS, is to release angiotensin II from its endogenous
precursor [1]. Angiotensin II, a potent vasoconstrictor, produces the
majority of the effects contributing to the RAS pathway, such as
direct vasoconstriction, enhancement of both catecholamine release
and neurotransmission within the peripheral nervous system, and
regulation of renal function [2].
ACE inhibitors (ACEI) are the first class of marketing drugs
targeting to the RAS system, yet all ACEI can cause hypotension,
hyperkalemia, and dry cough. Afterwards, research efforts on an-
giotensin receptor blocks which can replace ACE inhibitors as
anti-hypertension with less adverse effects have led to the discovery
of angiotensin II antagonists [3].
Angiotensin receptor blocks (ARBs), the second class to treat
hypertension and related cardiovascular disorders, are non-peptide
compounds that specifically block the binding of angiotensin II to
the AT1 receptor, by occupying the space among the seven trans-
membrane helices of the receptor protein and interacting with the
amino-acid residues in this region of the receptor molecule. The
ARBs effectively prevent or reverse all of the known effects of
angiorensin II, including rapid and slow pressor responses, stimu-
latory effects on the peripheral sympathetic nervous system, CNS
effects, release of catechol amines, secrestion of aldosterone, both
lower blood pressure and protect tissues from oxidative stress and
resultant CVD [4, 5]. Eight compounds have been marketed, in-
cluding losartan, valsartan, candesartan, irbesartan, olmesartan and
telmisartan [6].
In the previous work of our group, we have synthesized a series
of [1,2,4]triazole derivatives based on the SAR of losartan and
found that the compound biphenylmethyl [1,2,4]triazole (1) showed
potent AT1 antagonist activity (IC50 = 1.99 nM) [15]. On the basis
of the above study, compound 1 was chosen as the template in the
attempt to find new satisfactory anti-hypertension drugs. By conju-
gating 1 with NO-donor group, such as nitrooxy and substituted
furoxan moieties, a series of hybrid drugs were designed. As a re-
sult, the NO-sartan analogs 9a-f and 15a-f were synthesized and
their activities were evaluated.
Compared with ACEI, ARBs have fewer side effects, as they do
not inhibit the catabolism of bradykinin carried out by ACE enzyme
and, therefore, do not induce cough and angioedema. However, this
biopharmacological characteristic is also responsible for the weaker
effectiveness of this class of drugs, due to their inability to increase
the bradykinin level, leading to the decline of NO-induced vasore-
laxing activity. The importance of NO not only lies in its vasore-
laxing action, but also in its potent inhibition of platelet and neu-
trophil aggregation in the endothelium [7].
Cl
Cl
N
N
COOH
O
C4H9
N
*Address correspondence to these authors at the Department of Medicinal Chemistry,
China Pharmaceutical University, Nanjing 210009, People’s Republic of China; Tel:
+86-(0)25-83242366; Fax: +86-(0)25-83271480; E-mail: jpzhou668@163.com,
xmwu@cpu.edu.cn
Fig. (1). The structure of compound 1.
1570-1808/10 $55.00+.00
© 2010 Bentham Science Publishers Ltd.

Synthesis and Biological Study
Letters in Drug Design & Discovery, 2010, Vol. 7, No. 1
19
NH
NCOOEt
EtOH
Ether
ClCOOEt
CH2Cl2 /Et3N
CH3CH2CH2CH2COEt
CH3CH2CH2CH2CN
CH3CH2CH2CH2COEt
4
2
3
Cl
Cl
NHNH2
Cl
Cl
Cl
NaH/DMF
N
N
N
N
N
Cl
O
COOCH3
O
Et3N / Tol
COOCH3
N
C4H9
C4H9
H
BrH2C
5
6
7
Cl
Cl
N
Cl
Cl
N
N
N
N
COOH
NaOH/MeOH
O
COORBr
BrRBr
K2CO3/DMF/rt
O
C4H9
N
C4H9
1
8a-f
Cl
Cl
N
N
AgNO3
CH3CN
COORONO2
O
a: R=CH2CH2,
b: R=CH2CH2CH2,
C4H9
N
c: R=CH(CH3)CH2, d: R=CH2(CH2)2CH2,
e: R=CH2(CH2)3CH2, f: R=CH2(CH2)4CH2
9a-f
Scheme 1. Synthetic route of nitrooxy derivative 9a-f.
hibited Ang II (10－ mol/L)-induced contraction in a contrac-
tion-related. The results reported in Table 1 showed that the com-
pounds 9b (IC50 =1.98nM), 15b (IC50 =1.58nM) and 15d (IC50
=2.04nM) exhibited potent antagonistic activity of AT1 receptor,
which were similar to the marketed AT1 receptor antagonist losar-
tan (IC50 = 1.99 nM). The NO production in vitro were determined
by Greiss assay. The result showed that these compounds have
different levels of NO release. 9b, 15b, 15d, 15e had good maxi-
mum NO release amount of this series.
10
RESULTS AND DISCUSSION
Chemistry
Compounds 9a-f, 15a-f were prepared as shown in Scheme 1
and Scheme 2. The intermediate 5 was synthesized according to
reported methods [15]. Then 5 was converted to 7 with methyl
4'-(bromomethyl)biphenyl-2-carboxylate 6 and NaH in DMF.
Through saponification of 7 with NaOH, we obtained the key
compound 1. Then 1 was esterized with alkyl dibromide to give
8a-f which were further converted into their corresponding target
nitrooxy derivatives 9a-f by reaction with silver nitrate in acetoni-
trile under refluxing and in the darkness. In Scheme 2, the furoxans
14a-f were synthesized as described previously in which thiophenol
11 was used as the starting material. Then 1 was condensed with
14a-f respectively in CH2Cl2 in the presence of N,
N-dicyclohexylcarbodiimide (DCC) and a catalytic amount of N,
N-(dimethylamino)pyridine (DMAP) to afford the corresponding
target compounds 15a-f.
EXPERIMENTAL SECTION
General
Melting points were determined using a capillary apparatus
(RDCSY-I) and are reported directly. All of the compounds synthe-
sized were purified by column chromatography (CC) on silica gel
60 (200-300 mesh) and thin-layer chromatography (TLC) on silica
gel 60 F254 plates (250 μm; Qingdao Ocean Chemical Company,
China). Subsequently, they were routinely analyzed by IR (Shima-
dzu FTIR-8400S), 1H-NMR (Bruker ACF-300Q, 300 MHz), MS
(Hewlett-Packard 1100 LC/MSD spectrometer), and elemental
analysis (Elementar Vario EL III instrument).
Biological Activity
The synthesized compounds were evaluated for their antago-
nism of Ang II induced contraction in the rabbit thoracic aortic ring
with isolated rabbit aortic strips. Losartan was taken as a positive
control drug in the assays. The target compounds and losartan in-

20
Letters in Drug Design & Discovery, 2010, Vol. 7, No. 1
Zhang et al.
SH
SO2CH2COOH
HNO3
SCH2COOH
PhO2S
SO2Ph
O
H2O2
ClCH2COOH
N
N
O
13
10
11
12
Cl
HORO
Cl
SO2Ph
1/THF
N
N
O
HOROH
S
N
O
COORO
O
N
N
DCC/DMAP
O
O
N
O
N
O
14a-f
I5a-f
a: R=CH2CH2,
b: R=CH2CH2CH2,
c: R=CH(CH3)CH2,
d: R=CH2(CH2)2CH2, e: R=CH(CH3)CH2CH2, f: R=CH2CH=CHCH2
Scheme 2. Synthetic route of substituted furoxan derivatives 15a-f.
－10
Table 1. Inhibitory Activities of Ang II (10
the New Compounds
mol/L)-Induced Contraction in a Contraction-Related and Maximum NO Release Amount in vitro of
Compd.
R
IC50(nM)
NOmax(μM)
9a
9b
CH2CH2
CH2CH2CH2
3.79
1.98
4.93
6.55
12.02
13.13
5.97
1.58
7.65
2.04
4.53
8.31
1.99
1.99
5.6ꢁꢂꢃꢄꢅ
6.2ꢁꢂꢃꢄꢅ
4.7ꢁꢂꢃꢄꢅ
3.8ꢁꢂꢃꢄꢅ
2.3ꢁꢂꢃꢄꢅ
1.5ꢁꢂꢃꢄꢅ
5.8ꢁꢂꢃꢄꢅ
6.3ꢁꢂꢃꢄꢅ
4.0ꢁꢂꢃꢄꢅ
6.0ꢁꢂꢃꢄꢅ
6.1ꢁꢂꢃꢄꢅ
5.2ꢁꢂꢃꢄꢅ
NT
9c
CH (CH3)CH2
CH2(CH2)2CH2
CH2(CH2)3CH2
CH2(CH2)4CH2
CH2CH2
9d
9e
9f
15a
15b
15c
15d
15e
15f
losartan
1
CH2CH2CH2
CH(CH3)CH2
CH2(CH2)2CH2
CH(CH3)CH2CH2
CH2CH=CHCH2
NT
4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-[1,2,4]triazol-4(5
The intermediates
5 that were used to introduce the
H)-yl)methyl)biphenyl-2-carboxylic acid (1)
[1,2,4]triazole moieties were synthesized according to reported
methods [15].
7(0.205g, 0.5mmol) was stirred for 40 min in alcohol (10 mL)
and 10%NaOH (8 mL). The mixture was stirred for 3h under re-
fluxed. Then the solvent was evaporated in vacuo and the residue
taken up in diethyl ether. The resulting white solid was filtered,
washed with diethyl ether, and dried (0.139g, yield: 56.6%), white
solid, mp: 172～174ꢀ; MS(ESI, m/z): 496.2[M+1]+ ; IR(KBr,
cm-1): 2925.27, 1716.11, 1629.36, 1568.36, 1480.17, 1218.01,
1082.94; 1H-NMR(DMSO-d6), ꢀ(ppm): 0.80(t, 3H, CH3),
1.26-1.32(m, 2H, CH2), 1.48-1.53(m, 2H, CH2), 2.54(t, 2H, CH2),
5.00(s, 2H, CH2), 7.27-7.30(d, 2H, ArH), 7.35-7.39(m, 3H, ArH),
7.45-7.48(m, 1H, ArH), 7.54-7.62(m, 2H, ArH), 7.69-7.75(m, 3H,
ArH), 12.51(s, 1H, COOH).
Methyl-4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-[1,2,4]tri
azol-4(5H)-yl)methyl)biphenyl-2-carboxylate (7).
Sodium hydride (0.03g, 1.25mmol) was added to a stirred solu-
tion of 5 (0. 97g, 5 mmol) in dry DMF (10 mL) under nitrogen.
After 30 min the bromo derivative 6 (0.315g, 1.1mmol) was added,
and the resulting mixture was stirred for 3.5 h at 30ꢀ. The solvent
was removed in vacuo and the residue taken up in ethyl acetate and
water. The organic phase was separated, washed with brine, dried
(Na2SO4), and then concentrated. The residue was chromatographed
over silica gel in 4:1 petroleum ether-ethyl acetate to give an oil
which crystallized (0.43g, yield: 85.0%), white solid, mp:
128-130ꢀ. ESI-MS: 510[M+1]+
2-(nitrooxy)ethyl-4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H
-[1,2,4]triazol-4(5H)-yl)methyl)biphenyl-2-carboxylate (9a)

Synthesis and Biological Study
Letters in Drug Design & Discovery, 2010, Vol. 7, No. 1
21
A solution of 8a（0.271g，0.45mmol) in a small amount of
CH3CN (10 mL) was added to a stirred solution of AgNO3 (0.1g,
0.6mmol) in CH3CN (19 mL). Stirring was continued over 2 h at
room temperature in the dark, and then the precipitate was filtered
off, and the solvent was evaporated. The crude product was tritu-
rated with CHCl3 (20 mL) and filtered off to remove the unreacted
silver nitrate and AgBr. The solvent was evaporated to give 9a
(0.233g, yield: 89%).
CH2), 4.40(t, J=5.22Hz,2H,CH2), 5.02(s, 2H, CH2), 7.34-7.40(q,
4H, ArH), 7.43-7.47(d, 1H, ArH), 7.47-7.52(t, 1H, ArH),
7.56-7.59(m, 2H, ArH), 7.68-7.75(d, 2H, ArH), 7.77-7.79(d, 1H,
ArH).
5-(nitrooxy)pentyl-4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1
H-[1,2,4]triazol-4(5H)-yl)methyl)biphenyl-2-carboxylate (9e）
Colorless oil, MS(ESI, m/z): 649.1[M+K]+; IR(KBr, cm-1):
2960.85, 1720.12, 1627.23, 1438.39, 1278.34, 1050.95, 1027.34,
Compound 9b-f was synthesized from following the same pro-
cedure described above for the preparation of 9a.
1
862.56, 791.47, 759.48; H-NMR(DMSO-d6), ꢀ(ppm): 0.82(t, 3H,
CH3), 1.13-1.16(m, 2H, CH2), 1.30-1.34(m, 4H, CH2), 1.50-1.54(m,
4H, 2CH2), 2.56(t, 2H, CH2), 3.98(t, J=6.59Hz, 2H, CH2),4.435(t,
J=6.34Hz, 2H, CH2), 5.02(s, 2H, CH2), 7.32(s, 4H, ArH),
7.40-7.43(d, 1H, ArH), 7.46-7.52(t, 1H, ArH), 7.56-7.66(m, 2H,
ArH), 7.68-7.75(m, 3H, ArH).
4-(2-(4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-[1,2,4]triaz
ol-4(5H)-yl)methyl)biphenylcarbonyloxy)ethoxy)-3-(phenylsulfony
l)- [1,2,5]oxadiazole 2-oxide（15a）
A solution of 1 (0.228g, 0.5mmol), DCC (0.103g, 0.5mmol)
and DMAP (5.1 mg, 0.042mmol) in dry tetrahydrofuran (20 mL)
was stirred at room temperature for 10 h. After filtration, the filtrate
was evaporated to dryness in vacuo, and the crude product was
purified by column chromatography (petroleum ether /EtOAc 4:1 to
3:1) to yield the compounds (0.11g, yield: 38%).
6-(nitrooxy)hexyl-4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H
-[1,2,4]triazol-4(5H)-yl)methyl)biphenyl-2-carboxylate (9f）
Colorless oil, MS(ESI, m/z): 641.19[M+H]+; IR(KBr, cm-1):
2953.74, 1719.74, 1626.15, 1452.61, 1279.08, 1050.95, 1027.34,
1
866.11, 791.47, 763.03; H-NMR(DMSO-d6), ꢀ(ppm): 0.82(t, 3H,
Compound 15b-f was synthesized from 1 following the same
procedure described above for the preparation of 15a.
CH3), 1.13-1.16 (m, 2H, CH2), 1.30-1.34 (m, 6H, 3CH2), 1.50-1.54
(m, 4H, 2CH2), 2.55(t, 2H, CH2), 3.97(t, J=6.41Hz, 2H, CH2),
4.44(t, J=6.59Hz, 2H, CH2), 5.00(s, 2H, CH2), 7.32(s, 4H, ArH),
7.40-7.43(d, 1H, ArH), 7.46-7.52(t, 1H, ArH), 7.56-7.66(m, 2H,
ArH), 7.68-7.75(m, 3H, ArH).
Spectra Data
2-(nitrooxy)ethyl-4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H
4-(2-(4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-[1,2,4]triaz
ol-4(5H)-yl)methyl)biphenylcarbonyloxy)ethoxy)-3-(phenylsulfony
l)-[1,2,5]-oxadiazole 2-oxide (15a）
-[1,2,4]triazol-4(5H)-yl)methyl)biphenyl-2-carboxylate (9a）
Colorless oil, MS(ESI, m/z): 583.89[M-1]-; IR (KBr, cm-1):
2958.34, 1720.62, 1636.94, 1566.36, 1479.85, 1441.25, 1270.05,
Colorless oil, MS(ESI, m/z): 763.91; IR(KBr, cm-1):2953.74,
1721.34, 1616.56, 1552.30, 1450.41, 1360.19, 1246.45, 1169.77,
1086.49, 757.58, 597.43, 556.87; 1H-NMR(DMSO-d6), ꢀ(ppm):
0.79(t, 3H, CH3), 1.25-1.29(m, 2H, CH2), 1.45-1.49(m, 2H, CH2),
2.54(t, 2H, CH2), 4.44(S, 4H, 2CH2), 4.97(s, 2H, CH2), 7.25-7.33(q,
4H, ArH), 7.43-7.51(d, 1H, ArH), 7.54-7.55(m, 4H, ArH),
7.65-7.71(m, 3H, ArH), 7.74-7.84(m, 2H, ArH), 7.93-7.96(m, 2H,
ArH).
1
1242.96, 1132.75, 1090.12, 858.53, 791.71; H-NMR(DMSO-d6),
ꢀ(ppm): 0.81(t,3H,CH3), 1.28-1.32(m, 2H, CH2), 1.49-1.54(m, 2H,
CH2), 2.54(t, 2H, CH2), 3.42(t, J=5.14Hz, 2H, CH2), 4.00(t,
J=5.14Hz, 2H, CH2), 5.00(s, 2H, CH2), 7.27-7.30(q, 4H, ArH),
7.36-7.41(d, 1H, ArH), 7.43-7.49(t, 1H, ArH), 7.56-7.62(m, 2H,
ArH), 7.69-7.72(d, 2H, ArH), 7.77-7.79(d, 1H, ArH).
3-(nitrooxy)propyl-4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1
H-[1,2,4]triazol-4(5H)-yl)methyl)biphenyl-2-carboxylate (9b）
4-(3-(4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-[1,2,4]triaz
ol-4(5H)-yl)methyl)biphenylcarbonyloxy)propoxy)-3-(phenylsulfon
yl)-[1,2,5]-oxadiazole 2-oxide (15b）
Colorless oil, MS(ESI, m/z): 621.1[M+Na]+; IR(KBr, cm-1):
2960.85, 1719.70, 1630.27, 1477.49, 1441.31, 1276.92, 1125.59,
862.56; 1H-NMR(DMSO-d6), ꢀ(ppm): 0.82(t, 3H, CH3),
1.30-1.34(m, 2H, CH2), 1.49-1.55(m, 2H, CH2), 1.74-1.79(m, 2H,
CH2), 2.54(t, 2H, CH2), 4.07(t, J=6.17Hz, 2H, CH2), 4.27(t,
J=6.35Hz, 2H, CH2), 4.99(s, 2H, CH2), 7.27-7.30(q, 4H, ArH),
7.40(d, 1H, ArH), 7.47(t, 1H, ArH), 7.56-7.62(m, 2H, ArH), 7.70(d,
2H, ArH), 7.78(d, 1H, ArH).
Colorless oil, MS(ESI, m/z): 800.3[M+Na]+; IR(KBr, cm-1):
2960.85, 1716.90, 1614.64, 1552.81, 1450.39, 1168.25, 1086.49,
1
759.79, 597.43, 556.87; H-NMR(DMSO-d6), ꢀ(ppm): 0.79(t, 3H,
CH3), 1.28-1.33(m, 2H, CH2), 1.48-1.53(m, 2H, CH2), 1.82-1.86(m,
2H, CH2), 2.54(t, 2H, CH2), 4.11-4.16(m, 4H, 2CH2), 4.98(s, 2H,
CH2), 7.25-7.33(q, 4H, ArH), 7.43-7.51(d, 1H, ArH), 7.54-7.55(m,
4H, ArH), 7.65-7.71(m, 3H, ArH), 7.74-7.84(m, 2H, ArH),
7.93-7.96(m, 2H, ArH).
1-(nitrooxy)propan-2-yl4'-((3-butyl-1-(2,6-dichlorophenyl)-5-o
xo-1H-[1,2,4]triazol-4(5H)-yl)methyl)biphenyl-2-carboxylate (9c）
Colorless oil, MS(ESI, m/z): 621.3[M+Na]+; IR(KBr, cm-1):
2960.85, 1716.85, 1632.21, 1452.61, 1272.22, 1050.95, 1027.34,
4-(2-(4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-[1,2,4]triaz
ol-4(5H)-yl)methyl)biphenylcarbonyloxy)propoxy)-3-(phenylsulfon
yl)-[1,2,5]oxadiazole 2-oxide (15c）
1
1005.95, 763.71; H-NMR(DMSO-d6), ꢀ(ppm): 0.82(t, 3H, CH3),
1.07(dd, J=15.21, 6.55Hz, 3H, CH3), 1.30-1.34(m, 2H, CH2),
1.50-1.54(m, 2H, CH2), 2.57(t, 2H, CH2), 4.13-4.15(m, 1H, CH),
4.32-4.36(m, 1H, CH), 4.56-4.59(m, 1H, CH), 5.01(s, 2H, CH2),
7.27-7.30(q, 4H, ArH), 7.39(d, 1H, ArH), 7.47(t, 1H, ArH),
7.56-7.62(m, 2H, ArH), 7.69-7.72(d, 2H, ArH), 7.77-7.79(d, 1H,
ArH).
Colorless oil, MS(ESI, m/z): 800.4[M+Na]+; IR(KBr, cm-1):
2960.85, 1716.90, 1614.64, 1552.81, 1450.39, 1168.25, 1086.49,
1
759.79, 597.43, 556.87; H-NMR(DMSO-d6), ꢀ(ppm): 0.79(t, 3H,
CH3), 1.11-1.13(m, 3H, CH3), 1.30(m, 2H, CH2), 1.56(m, 2H, CH2),
2.54(t, 2H, CH2), 4.23(d, 1H, CH), 4.38(d, 1H, CH), 4.99(s, 2H,
CH2), 5.25(m, 1H, CH), 7.25-7.33(q, 4H, ArH),7.43-7.51(d, 1H,
ArH), 7.54-7.55(m, 4H, ArH), 7.65-7.71(m, 3H, ArH),
7.74-7.84(m, 2H, ArH), 7.93-7.96(m, 2H, ArH).
4-(nitrooxy)butyl-4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H
-[1,2,4]triazol-4(5H)-yl)methyl)biphenyl-2-carboxylate (9d）
Colorless oil, MS(ESI, m/z): 613.11[M+H]+; IR(KBr, cm-1):
2953.74, 1719.62, 1626.48, 1438.39, 1278.52, 1278.52, 1129.15,
4-(4-(4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-[1,2,4]triaz
ol-4(5H)-yl)methyl)biphenylcarbonyloxy)butoxy)-3-(phenylsulfony
l)-[1,2,5]oxadiazole 2-oxide (15d)
1
862.56, 791.47, 763.03; H-NMR(DMSO-d6), ꢀ(ppm): 0.82(t, 3H,
Colorless oil, MS(ESI, m/z): 814.3[M+Na]+; IR(KBr, cm-1):
2960.85, 1716.96, 1613.79, 1552.23, 1449.56, 1168.25, 1085.33,
CH3), 1.26-1.30(m, 2H, CH2), 1.41-1.45(m, 4H, 2CH2),
1.54-1.58(m, 2H, CH2), 2.57(t, 2H, CH2), 4.01(t, J=5.55Hz, 2H,

22
Letters in Drug Design & Discovery, 2010, Vol. 7, No. 1
Zhang et al.
759.79, 597.43; 1H-NMR(DMSO-d6), ꢀ(ppm): 0.79(t, 3H, CH3),
1.05(d, 3H, CH3), 1.28-1.33(m, 2H, CH2), 1.47-1.51(m, 2H, CH2),
1.80-1.84(m, 2H, CH2), 2.54(t, 2H, CH2), 4.06-4.28(m, 1H, CH),
5.00(s, 2H, CH2), 7.25-7.33(q, 4H, ArH), 7.43-7.51(d, 1H, ArH),
7.54-7.55(m, 4H, ArH), 7.65-7.71(m, 3H, ArH), 7.74-7.84(m, 2H,
ArH), 7.93-7.96(m, 2H, ArH).
4-(3-(4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-[1,2,4]triaz
ol-4(5H)-yl)methyl)biphenylcarbonyloxy)butoxy)-3-(phenylsulfony
l)-[1,2,5]oxadiazole 2-oxide (15e)
Colorless oil, MS(ESI, m/z): 814.3[M+Na]+; IR(KBr, cm-1):
2960.85, 1718.96, 1613.79, 1552.23, 1449.56, 1168.25, 759.79;
1H-NMR(DMSO-d6), ꢀ(ppm): 0.79(t, 3H), 1.28-1.33(m, 2H, CH2),
1.47-1.54(m, 6H, 3CH2), 2.54(t, 2H, CH2), 4.06(t, 2H, CH2), 4.28(t,
2H, CH2), 5.00(s, 2H, CH2), 7.25-7.33(q, 4H, ArH), 7.43-7.51(d,
1H, ArH), 7.54-7.55(m, 4H, ArH), 7.65-7.71(m, 3H, ArH),
7.74-7.84(m, 2H, ArH), 7.93-7.96(m, 2H, ArH).
CONCLUSION
In conclusion, we have obtained a new series of oxide-donating
derivatives of [1,2,4]triazol-5(4H)-one derivatives. These new
compounds were confirmed that NO-sartans are actually pharma-
codynamic hybrids possessing both the AT1-antagonist activity of
sartans and a “slow NO donor”. In addition, they seemed to possess
antihypertensive properties not inferior to those of the “native”
sartans. Further biological evaluations on these compounds, such as
the beneficial roles played by NO in the cardiovascular system are
currently in progress.
ACKNOWLEDGEMENT
The work was supported by the key project of Chinese Ministry
of Education (No. 103089).
REFERENCES
4-(4-(4'-((3-butyl-1-(2,6-dichlorophenyl)-5-oxo-1H-1,2,4-triazo
l-4(5H)-yl)methyl)biphenylcarbonyloxy)but-2-enyloxy)-3-(phenyls
ulfonyl)-[1,2,5]oxadiazole 2-oxide (15f)
[1]
Mohammad, A. Z.; Suzanne, O.; David, A. C. Drugs targeting the
renin-angiotensin-aldosterone system. Nat. Rev. Drug Discov., 2002, 1,
621-636.
Conlin, P. R. Angiotensin II Antagonists in the Treatment of Hypertension:
More Similarities than Differences. J. Clin. Hypertens., (Greenwich), 2000,
2(4), 253-257.
[2]
Colorless oil, MS(ESI, m/z): 805.3[M+NH4]+; IR(KBr, cm-1):
2932.38, 1715.94, 1613.79, 1547.83, 1440.90, 1368.69, 1168.25,
1085.33, 759.79, 597.43; 1H-NMR(DMSO-d6), ꢀ(ppm): 0.80(t, 3H,
CH3), 1.28-1.33 (m, 2H, CH2), 1.47-1.54 (m, 2H, CH2),
2.25-2.29(m, 2H, CH2), 4.86(s, 2H, CH2), 5.00(s, 2H, CH2), 5.25(s,
2H, 2CH), 7.25-7.33(q, 4H, ArH), 7.43-7.51(d, 1H, ArH),
7.54-7.55(m, 4H, ArH), 7.65-7.71(m, 3H, ArH), 7.74-7.84(m, 2H,
ArH), 7.93-7.96(m, 2H, ArH).
[3]
[4]
Ito, M. ACE: gene, biosynthesis and functions. Nippon Rinsho, 2005,
63(Suppl 3), 22-27.
Perret-Guillaume, C.; Joly, L.; Jankowski, P.; Benetos, A. Benefits of the
RAS blockade: clinical evidence before the ONTARGET study. J. Hyper-
tens., 2009, 27(Suppl 2), S3-S7.
Mathur, G.; Noronha, B.; Rodrigues, E.; Davis, G. The role of angiotensin II
type 1 receptor blockers in the prevention and management of diabetes mel-
litus. Diabetes Obes. Metab., 2007, 9(5), 617-629.
[5]
[6]
[7]
[8]
Burnier, M.; Brunner, H. R. Angiotensin II receptor antagonists - antihyper-
tensive agents. Expert Opin. Investig. Drugs, 1997, 6, 489-500.
Millatt, L. J.; Abdel-Rahman, E. M.; Siragy, H. M. Angiotensin II and nitric
oxide: a question of balance. Regul. Pept., 1999, 81(1-3), 1-10.
Wessler, C.; Homann, A.; Fricke, U.; Lehmann, J. NO donors, part 8 [1]:
synthesis and vasodilating activities of substituted benzylnitrates compared
to cyclohexylmethylnitrate and GTN. Eur. J. Med. Chem., 2003, 38, 581-586.
Engelhardt, F. C.; Shi, Y. J.; Cowden, C. J.; Conlon, D. A.; Pipik, B.; Zhou,
G.; McNamara, J. M.; Dolling, U. H. Synthesis of a NO-releasing prodrug of
rofecoxib. J. Org. Chem., 2006, 71(2), 480-491.
Buonsanti, M. F.; Bertinaria, M.; Stilo, A. D.; Cena, C.; Fruttero, R.; Gasco,
A. Nitric oxide donor beta2-agonists: furoxan derivatives containing the
fenoterol moiety and related furazans. J. Med. Chem., 2007, 50(20),
5003-5011.
Chen, L.; Zhang, Y.; Kong, X.; Peng, S.; Tian, J. Synthesis and biological
evaluation of nitric oxide-releasing derivatives of oleanolic acid as inhibitors
of HepG2 cell apoptosis. Bioorg. Med. Chem. Lett., 2007, 17(11), 2979-2982.
Breschi, M. C.; Calderone, V.; Digiacomo, M.; Martelli, A.; Martinotti, E.;
Minutolo, F.; Rapposelli, S.; Balsamo, A. NO-sartans: a new class of phar-
macodynamic hybrids as cardiovascular drugs. J. Med. Chem., 2004, 47(23),
5597-5600.
Breschi, M. C.; Calderone, V.; Digiacomo, M.; Macchia, M.; Martelli, A.;
Martinotti, E.; Minutolo, F.; Rapposelli, S.; Rossello, A.; Testai, L.; Bal-
samo, A. New NO-releasing pharmacodynamic hybrids of losartan and its
active metabolite: design, synthesis, and biopharmacological properties. J.
Med. Chem., 2006, 49(8), 2628-2639.
Li, Y. Q.; Ji, H.; Zhang, Y. H.; Shi, W. B.; Meng, Z. K.; Chen, X. Y.; Du, G.
T. WB1106, a novel nitric oxide-releasing derivative of telmisartan, inhibits
hypertension and improves glucose metabolism in rats. Eur. J. Pharmacol.,
2007, 577(1-3), 100-108.
Xu, J.Y.; He, Q. H.; Wei, Z. Synthesis and Biological Activities of
4-Substituted-3-alky-4,5-dihydro-1-(3-chloro-4-fluorophenyl)-1,2,4-triazol-5
-one. Chin. J. Org. Chem., 2006, 26(1), 123-128.
Kubo, K.; Inada, Y.; Kohara, Y.; Sugiura, Y.; Ojima, M.; Itoh, K.; Furukawa,
Y.; Nishikawa, K.; Naka, T. Nonpeptide angiotensin II receptor antagonists.
Synthesis and biological activity of benzimidazoles. J. Med. Chem., 1993,
36(12), 1772-1784.
BIOLOGY
AT1-Antagonist Activity
The compounds were tested for antagonist activity in rabbit
aortic rings [16]. Male New Zealand white rabbits (2-2.5kg) were
sacrificed using an overdose of pentobarbital and exsanguinated via
the carotid arteries. The thoracic aorta was removed, cleaned of
adherent fat and connective tissue, and then cut into 3-mm ring
segments. For the measurement of antagonistic activity, paired
rings from the same rabbits were used; one was exposed to increas-
ing concentrations of AII, (at 30-min intervals), and a second ring
was exposed to increasing concentrations of AII in the presence of
the test compound which was added 5 min prior to the addition of
AII. The concentration-response curves for AII in the presence of
the antagonist were evaluated in terms of the percent of the maxi-
mal contraction of the control ring exposed only to AII values for
AII were calculated from the AII concentration-response curves
while IC50 were determined.
[9]
[10]
[11]
[12]
[13]
[14]
Measurement of NO Release
The different levels of NO production in vitro were determined
by Greiss assay [17]. Culture medium, after the treatment period,
was removed and the compound (100μl) was reacted with 50μl
sulfanilamide (10mg/ml in 5% orthophosphoric acid) and 50μl
N-(1-naphthyl)ethylenediamine (1mg/ml) in a multiwell microtiter
plate. Similarly, different concentrations of sodium nitrite were
reacted with sulfanilamide and N-(1-naphthyl)ethylenediamine to
produce a standard curve for determining the nitrite (NO) concen-
tration in each sample. The absorbance was measured at a wave-
length of 570nm on a multiwell plate reader and the nitrite concen-
tration in each sample was determined.
[15]
[16]
[17]
Villarroya, M.; Herrero, C. J.; Ruiz-Nuno, A.; de Pascual, R.; del Valle, M.;
Michelena, P.; Grau, M.; Carrasco, E.; Lopez, M. G.; Garcia, A. G.
PF9404C, a new slow NO donor with beta receptor blocking properties. Br.
J. Pharmacol., 1999, 128(8), 1713-1722.