Synthesis and bioactivity of substituted indan-1-ylideneaminoguanidine derivatives

Article abstract of DOI:10.1016/j.ejmech.2009.04.036

In our efforts to discover more potent and lasting NHE1 inhibitors, we designed and synthesized a series of substituted indan-1-ylidene aminoguanidine derivatives (5). NHE1 inhibitory activity of twenty-one compounds 5 was evaluated in a rat platelet swelling assay. It is found that most of the tested compounds possess NHE1 inhibitory effects. 2-(5-methoxybenzimidazol-2-ylthio)-5-chloro-2,3-dihydroinden-1-ylidene aminoguanidine hydrobromide (5m) proved to be sixty-nine times more potent than cariporide. Furthermore, when tested in vivo, compound 5m also displayed superior cardioprotective effects against SD rat myocardial ischemic-reperfusion injury over those of cariporide.

Full text of DOI:10.1016/j.ejmech.2009.04.036

European Journal of Medicinal Chemistry 44 (2009) 3771–3776
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis and bioactivity of substituted indan-1-ylidene
aminoguanidine derivatives
,
a
b
a
Rui Zhang a, Jin Dong a, Yun-gen Xu a , Wei-yi Hua , Na Wen , Qi-dong You
*
a Department of Medicinal Chemistry, China Pharmaceutical University, Tongjiaxiang 24, Nanjing 210009, China
b Department of Pharmacology, China Pharmaceutical University, Nanjing 210009, China
a r t i c l e i n f o
a b s t r a c t
Article history:
In our efforts to discover more potent and lasting NHE1 inhibitors, we designed and synthesized a series
of substituted indan-1-ylidene aminoguanidine derivatives (5). NHE1 inhibitory activity of twenty-one
compounds 5 was evaluated in a rat platelet swelling assay. It is found that most of the tested compounds
possess NHE1 inhibitory effects. 2-(5-methoxybenzimidazol-2-ylthio)-5-chloro-2,3-dihydroinden-1-yli-
dene aminoguanidine hydrobromide (5m) proved to be sixty-nine times more potent than cariporide.
Furthermore, when tested in vivo, compound 5m also displayed superior cardioprotective effects against
SD rat myocardial ischemic–reperfusion injury over those of cariporide.
Received 25 July 2008
Received in revised form
20 April 2009
Accepted 23 April 2009
Available online 5 May 2009
Keywords:
NHE1 inhibitors
Ó 2009 Elsevier Masson SAS. All rights reserved.
Alkylene aminoguanidine derivatives
Indan-1-one derivatives
Synthesis
1. Introduction
[15,16], encouraged us to identify a novel NHE1 inhibitor with an
aminoguanidine group. Previously, we found that the inhibitory
The Naþ/Hþ exchangers (NHE) comprise a family of membrane
proteins that are involved in the transport of Hþ in exchange for
Naþ [1–3]. To date, nine NHE isoforms (NHE1–NHE9) have been
identified in various organs in the human body. NHE1 is involved in
numerous physiological processes in mammals, including regula-
tion of intracellular pH, cell-volume control, cytoskeletal organi-
zation, heart disease and cancer [4–7]. During ischemia and
reperfusion of the myocardium, NHE1 activity catalyzes increased
uptake of intracellular sodium. This in turn is exchanged for
extracellular calcium by the Naþ/Ca2þ exchanger resulting in
calcium overload and damage to the myocardium, such as
myocardial infarction activation, stunning and tissue necrosis [8,9].
NHE1 inhibitors, which competitively inhibit NHE1 function and
reduce Naþ and Ca2þ influx, would prevent damage to the
myocardium in ischemia–reperfusion [3,10].
effect of 2-benzimidazol-2-ylthio-1-(4-nitro phenylethylidene)
aminoguanidine (CPU-X-050519, IC50 ¼ 1.17 nM) (Fig. 2) on rat
platelet NHE1 is fifty-five times more potent than that of cariporide
[17]. As the extension of our efforts to increase the NHE1 inhibitory
activity and improve the stability due to the imine structure of CPU-
X-050519, we designed a series of substituted indan-1-ylidene
aminoguanidine derivatives 5a–u (Fig. 2). This paper describes the
synthesis and preliminary results of biological evaluation.
2. Results and discussion
2.1. Synthesis
Synthetic routes of target compounds are depicted in Scheme 1.
2-Bromo-indan-1-ones 2, obtained by bromination of indan-1-
ones 1 with copper (II) bromide [18], were reacted with benzimi-
dazol-(or benzothiazol)-2-thiols 3 to offer 2-(benzimidazol-(or
benzothiazol)-2-ylthio)-indan-1-ones 4, which were then treated
with aminoguanidine hydrochloride to give target compounds 5
(Table 1).
When compounds 1 were brominated with copper (II) bromide
according to a modified method [19], compounds 2 were obtained
in good yields with only small amounts of dibrominated by-prod-
ucts. The reaction between compounds 2 and compounds 3 could
be carried out in dimethylformamide (DMF) in the absence of an
While most known NHE1 inhibitors are acylguanidines based on
diverse aryl ring templates including benzene, pyrazole, quinoline,
etc. [9–14], few studies have been carried out on the non-acyl-
guanidine NHE1 inhibitors. T-162559 (Fig. 1), an aminoguanidine
derivative with a more potent NHE1 inhibitory effect against
ischemia and reperfusion injury than cariporide and eniporide
* Corresponding author. Tel.: þ86 25 83322067; fax: þ86 25 83271487.
E-mail address: xu_yungen@hotmail.com (Y.-g. Xu).
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.04.036

3772
R. Zhang et al. / European Journal of Medicinal Chemistry 44 (2009) 3771–3776
NH
H
.2CH SO H
3
3
CH
N
N
N
NH
2
3
CH
3
CH
3
CH
3
H C
3
H
N
NH
2
NH
2
N
H CO S
.CH SO H
3 3
3
2
H CO S
3
2
O
NH
2
O
NH
2
F
T-162559
Cariporide
Eniporide
Fig. 1. The structure of cariporide, T-162559 and CPU-X-050519.
alkali metal catalyst. Using such catalysts brought about the
formation of undesirable side reactions. When compounds 4
reacted with aminoguanidine hydrochloride in the presence of
a methanol solution saturated with hydrogen chloride (HCl) gas,
compounds 5 could be obtained as their hydrochloride salt.
injury of compound 5m at high (1 mg/kg), medium (0.5 mg/kg) and
low (0.25 mg/kg) dose levels were comparable with cariporide
(1 mg/kg). Further pharmacological studies are in progress.
4. Experiment protocol
Melting points were determined on a RDCSY- I capillary appa-
ratus and were uncorrected. The IR spectra (in KBr pellets) were
recorded on a Nicolet Impact 410 spectrophotometer. The 1H NMR
spectra were recorded on a Brucker AV-300 or AV-500 NMR spec-
trometer using TMS as an internal standard and chemical shifts
2.2. Biological activity
The NHE1 inhibitory activities of twenty-one target compounds
5a–u and cariporide were evaluated by rat platelet swelling assay
(PSA). The experimental procedure was similar to the literature
[20,21], with minor modifications. The PSA results (Table 2) showed
that most of the tested compounds inhibited rat platelet NHE1 in
a concentration-dependent manner. Compounds 5a, 5g, 5m, 5o and
5p were markedly superior to cariporide in NHE1 inhibition. The
IC50 value of compound 5m was 0.94 nM, making it sixty-nine
times more potent than cariporide (IC50 ¼ 65.0 nM).
were given in
d ppm with tetramethylsilane (TMS). Mass spectra
were recorded on an Agilent 1100 series LC/MSD Tarp (SL). All
solvents were purchased from commercial sources and used as
received unless otherwise stated.
4.1. General procedure for synthesis of compounds 2
In comparison with the compounds possessing the same
substituent in the indane ring, introduction of a benzothiazole ring
instead of a benzimidazole ring led to an improvement of the in
vitro activity (5p vs 5b, 5q vs 5c, 5s vs 5d, and 5t vs 5e). This may be
due to the sulfur atom in the benzimidazole ring which favors the
interaction with the docking site in NHE1.
The compounds showing good NHE1 inhibitory activity were
further investigated for their cardioprotective effects against
ischemia–reperfusion injury in SD rat hearts [22]. The infarct size
and the CK level of cariporide were 45.74 ꢀ 3.33% and 3.53 ꢀ
0.97 U/ml, respectively. Compounds 5a, 5m and 5o exhibited
a good cardioprotective efficacy both in vitro and in vivo (Table 3).
Especially, compound 5m significantly reduced the infarct size to
36.16 ꢀ 2.58% and the CK level to 2.82 ꢀ 0.87 U/ml at a dose of
1 mg/kg.
To a solution of (un)substituted indan-1-ones (1) (26 mmol) in
chloroform/ethyl acetate (1:1, 100 ml), cupric bromide (52 mmol)
was added portionwise with stirring under reflux (60%, 24% and
16% each portion), the second and third parts of cupric bromide
were added after black cupric bromide was transformed into white
cuprous bromide. After completion of addition of cupric bromide,
the reaction mixture was stirred and refluxed for 0.5–2 h. The
mixture was filtered, and the filtrate was decolorized and filtered.
The filtrate was concentrated to dryness under reduced pressure,
and the residue was recrystallised from methanol to give
(un)substituted 2-bromo-1-indanones (2) as crystals in 67–91%
yield [19].
4.2. General procedure for synthesis of compounds 4
3. Conclusion
A mixture of (un)substituted 2-mercaptobenzimidazoles (3)
(10 mmol) and (un)substituted 2-bromo-1-indanones (2) (10 mmol)
in DMF (20 ml) was stirred at 50 ꢁC for 4 h. After cooling, the
mixture was poured into ice-water (300 ml) and filtered, washed
with water. The residue was purified by silica gel column chroma-
tography (petroleum/EtOAC ¼ 2:1).
We investigated a series of substituted indan-1-ylidene amino-
guanidine derivatives 5 on the basis of the structure of an initial
lead compound CPU-X-050519. It is found that seven compounds
showed more potent NHE1 inhibitory activity than cariporide
among the twenty-one tested compounds in vitro. Four of the
seven compounds were selected for in vivo testing, and the car-
dioprotective effect against SD rat myocardial ischemic–reperfusion
2-(Benzimidazol-2-ylthio)-2,3-dihydroinden-1-one hydrobromide
(4a): Yield 80.8%, gray solid, m.p. 199–202 ꢁC. 1H NMR (CDCl3,
300 MHz)
d: 3.10 (dd, 1H, J1 ¼4.3 Hz, J2 ¼17.6 Hz, indanone 3-H),
NH2
N
NH2
N
N
N
NH2
NH2
R2
N
S
N
N
S
n HCl
X
NO2
R1
H
5a-u
CPU-X-050519
Fig. 2. Synthetic design of compounds 5a–u.

R. Zhang et al. / European Journal of Medicinal Chemistry 44 (2009) 3771–3776
3773
R2
N
O
O
SH
CuBr2
X
3a-d
Br
EtOAc / CHCl3
R1
R1
1a-i
DMF
2a-i
compds R2
X
compds
R1
H
compds
R1
3a
3b
3c
3d
H
NO2
OCH3 NH
H
NH
NH
1a, 2a
1b, 2b
6-OCH3
1c, 2c 5,6-(OCH3)2 1d, 2d 4,5,6-(OCH3)3
1e, 2e
1g, 2g
1i, 2i
4-Cl
6-Cl
6-F
1f, 2f
5-Cl
4,6-Cl2
S
1h, 2h
NH2
NH2
N
O
NH
N C NH2
R2
N
H
N
X
R2
H2N
N
X
S
S
n HCl
HCl / MeOH
R1
R1
4a-u
5a-u
R1 = H, 4-Cl, 5-Cl, 6-Cl, 6-F, 6-OCH3,
4,6-Cl2, 5,6-(OCH3)2, 4,5,6-(OCH3)3
R2 = H, OCH3, NO2
X = NH, S
Scheme 1. Synthesis of compounds 5.
4.03 (dd, 1H, J1 ¼8.2 Hz, J2 ¼17.6 Hz, indanone 3-H), 5.43 (dd, 1H,
J1 ¼4.3 Hz, J2 ¼ 8.2 Hz, indanone 2-H), 7.37–7.45 (m, 5H, ArH), 7.63–
7.70 (m, 3H, ArH).
J2 ¼ 8.3 Hz, indanone 2-H), 6.97 (s, 1H, indanone 4-H), 7.20 (s, 1H,
indanone 7-H), 7.49–7.52 (m, 2H, ArH), 7.82–7.85 (m, 2H, ArH). MS
(ESI(þ), 70 V) m/z: 341 [M þ H]þ.
2-(Benzimidazol-2-ylthio)-5,6-dimethoxy-2,3-dihydroinden-1-
one hydrobromide (4b): Yield 42.9%, white solid, m.p. 242–245 ꢁC.
2-(Benzimidazol-2-ylthio)-4,5,6-trimethoxy-2,3-dihydroinden-1-
one (4c): Yield 52.1%, white solid, m.p. 70–74 ꢁC. 1H NMR (CDCl3,
1H NMR (CDCl3, 300 MHz)
indanone 3-H), 3.89 (dd, 1H, J1 ¼8.3 Hz, J2 ¼ 17.4 Hz, indanone 3-H),
3.95 (s, 3H, OCH3), 4.04 (s, 3H, OCH3), 4.71 (dd, 1H, J1 ¼4.2 Hz,
d
: 3.06 (dd, 1H, J1 ¼4.2 Hz, J2 ¼ 17.4 Hz,
300 MHz)
d
: 3.00 (dd, 1H, J1 ¼3.6 Hz, J2 ¼18.0 Hz, indanone 3-H),
3.77 (dd, 1H, J1 ¼8.1 Hz, J2 ¼18.0 Hz, indanylidene 3-H), 3.92 (s, 3H,
OCH3), 3.97 (s, 3H, OCH3), 3.99 (s, 3H, OCH3), 4.40 (dd, 1H,
Table 1
NH2
Characterization table of compounds 5.
N
N
1
3'
N
NH2
4'
7'
R2
7
6
5
5'
S
HCl
n
2'
2
X
1'
6'
3
R1
4
Compd. no.
R1
R2
X
n
Mol. formula
m.p. (ꢁC)
Analysis (%)
Found (calculated)
C
H
N
5a
5b
5c
5d
5e
5f
5g
5h
5i
H
H
H
H
H
H
H
NO2
NO2
NO2
NO2
NO2
OCH3
OCH3
OCH3
H
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
NH
S
2
2
1
–
1
–
1
1
1
1
1
2
1
1
1
2
1
2
1
1
2
C17H16N6S$2HCl$3H2O
C19H20N6O2S$2HCl$H2O
C20H22N6O3S$HCl$H2O
181 (dec.)
165 (dec.)
169–171
178–179
158–160
177–178
193–195
180–182
177–179
177–180
176–178
196–198
160–163
158–160
138–140
172 (dec.)
153–155
133–135
168–170
149–152
145–147
43.93 (44.06)
46.82 (46.82)
48.92 (49.03)
53.85 (53.75)
46.36 (46.05)
49.88 (49.82)
46.68 (46.84)
45.65 (45.67)
44.18 (44.26)
43.18 (43.41)
45.45 (45.44)
46.18 (46.35)
47.39 (47.48)
49.16 (49.26)
49.57 (49.36)
45.50 (45.24)
46.68 (46.55)
43.65 (43.46)
47.17 (47.11)
45.29 (45.23)
44.45 (44.16)
5.26 (5.22)
4.83 (4.96)
5.10 (5.35)
4.37 (4.25)
4.49 (4.55)
3.49 (3.57)
4.16 (4.16)
4.70 (4.60)
3.54 (3.50)
3.68 (3.64)
3.57 (3.70)
4.89 (4.97)
4.51 (4.43)
4.65 (4.59)
4.42 (4.60)
4.65 (4.60)
4.90 (5.08)
3.52 (3.65)
3.63 (3.72)
3.85 (4.02)
3.85 (3.92)
17.89 (18.14)
16.96 (17.24)
17.10 (17.15)
21.93 (22.12)
19.07 (18.96)
20.46 (20.51)
22.34 (22.49)
18.35 (18.64)
20.99 (21.25)
20.89 (20.85)
21.75 (21.82)
18.17 (18.02)
18.29 (18.46)
18.78 (19.15)
15.74 (15.99)
14.02 (13.88)
13.61 (13.57)
14.63 (14.91)
16.49 (16.16)
15.26 (15.51)
15.04 (15.15)
5,6-(OCH3)2
4,5,6-(OCH3)3
5-Cl
6-Cl
4,6-Cl2
H
4,5,6-(OCH3)3
5-Cl
6-Cl
6-F
H
5-Cl
C17H15ClN6S$0.5H2O
C17H15ClN6S$HCl$2H2O
C17H14Cl2N6S$0.25H2O
C17H15N7O2S$HCl$H2O
C20H21N7O5S$HCl$H2O
C17H14ClN7O2S$HCl$0.5H2O
C17H14ClN7O2S$HCl$H2O
C17H14FN7O2S$HCl$0.75H2O
C18H18N6OS$2HCl$1.5H2O
C18H17ClN6OS$HCl$H2O
C18H17FN6OS$HCl$H2O
C18H17N5OS2$HCl$H2O
C19H19N5OS2$2HCl$H2O
C20H21N5OS2$HCl$2H2O
C17H14ClN5S2$2HCl$0.5H2O
C17H14ClN5S2$HCl$0.5H2O
5j
5k
5l
5m
5n
5o
5p
5q
5r
5s
5t
6-F
6-OCH3
5,6-(OCH3)2
4,5,6-(OCH3)3
4-Cl
5-Cl
6-Cl
H
H
H
H
H
H
S
S
S
S
S
S
C17H14ClN5S2$HCl$1.5H2O
5u
6-F
C17H14FN5S2$2HCl$H2O

3774
R. Zhang et al. / European Journal of Medicinal Chemistry 44 (2009) 3771–3776
Table 2
7.54 (d, 1H, J ¼ 7.6 Hz, indanone 4-H), 7.70 (d, 1H, J ¼ 7.6 Hz, ArH),
NHE1 inhibitory activities of compounds 5.
7.68 (d, 1H, J ¼ 8.9 Hz, ArH), 8.00 (dd, 1H, J1 ¼ 2.2 Hz, J2 ¼ 8.9 Hz,
ArH), 8.17 (d, 1H, J ¼ 2.2 Hz, ArH).
Compd.
PSA
Compd.
PSA
Compd.
PSA
2-(5-Nitrobenzimidazol-2-ylthio)-4,5,6-trimethoxy-2,3-dihy-
droinden-1-one hydrobromide (4h): Yield 41.9%, yellow solid, m.p.
IC50 (nM)a
IC50 (nM)a
IC50 (nM)a
5a
5b
5c
5d
5e
5f
1.73
11.2
10.8
5h
5i
5j
5k
5l
5m
5n
31.5
12.2
38.9
38.0
16.8
0.94
25.5
5o
5p
5q
5r
5s
5t
1.90
2.44
1.98
20.3
2.34
181–183 ꢁC. 1H NMR (CDCl3, 300 MHz,)
d
: 3.02 (dd, 1H, J1 ¼3.6 Hz,
J2 ¼ 18.0 Hz, indanone 3-H), 3.80 (dd, 1H, J1 ¼8.1 Hz, J2 ¼18.0 Hz,
indanone 3-H), 3.95 (s, 3H, OCH3), 3.97 (s, 3H, OCH3), 3.98 (s, 3H,
OCH3), 4.44 (dd, 1H, J1 ¼3.6 Hz, J2 ¼ 8.1 Hz, indanone 2-H), 7.10 (s,
1H, indanone 7-H), 7.62 (d, 1H, J ¼ 8.7 Hz, ArH), 8.19 (dd, 1H,
J1 ¼ 2.1 Hz, J2 ¼ 8.8 Hz, ArH), 8.50 (d, 1H, J ¼ 2.1 Hz, ArH).
21.4
326.2
653.8
1.74
34.6
287.3
5g
5u
a
The IC50 value of cariporide in the same testing was 65.0 nM.
2-(5-Nitrobenzimidazol-2-ylthio)-5-chloro-2,3-dihydroinden-1-
one hydrobromide (4i): Yield 57.4%, white solid, m.p. 186–188 ꢁC. 1H
NMR (CDCl3, 300 MHz)
d
: 3.21 (dd, 1H, J1 ¼4.2 Hz, J2 ¼18.3 Hz,
J1 ¼3.6 Hz, J2 ¼ 8.1 Hz, indanone 2-H), 7.08 (s, 1H, indanone 7-H),
7.26–7.29 (m, 2H, ArH), 7.59–7.62 (m, 2H, ArH).
2-(Benzimidazol-2-ylthio)-5-chloro-2,3-dihydroinden-1-one
hydrobromide (4d): Yield 59.9%, light yellow solid, m.p. 158–161 ꢁC.
indanone 3-H), 3.88 (dd,1H, J1 ¼8.4 Hz, J2 ¼18.3 Hz, indanone 3-H),
4.43 (dd, 1H, J1 ¼4.2 Hz, J2 ¼ 8.4 Hz, indanone 2-H), 7.44–7.55 (m,
2H, ArH), 7.67 (d, 1H, J ¼ 7.5 Hz, ArH), 7.85 (d, 1H, J ¼ 8.4 Hz, ArH),
8.18 (d, 1H, J ¼ 8.5 Hz, ArH), 8.54 (s, 1H, ArH).
1H NMR (CDCl3, 300 MHz)
d
: 3.14 (dd, 1H, J1 ¼4.2 Hz, J2 ¼18.3 Hz,
2-(5-Nitrobenzimidazol-2-ylthio)-6-chloro-2,3-dihydroinden-1-
one hydrobromide (4j): Yield 37.1%, yellow solid. It was used directly
in the next step without further purification.
indanone 3-H), 3.83 (dd,1H, J1 ¼8.4 Hz, J2 ¼ 18.3 Hz, indanone 3-H),
4.34 (dd, 1H, J1 ¼4.2 Hz, J2 ¼ 8.4 Hz, indanone 2-H), 7.24–7.28 (m,
2H, ArH), 7.44 (d, 1H, J ¼ 8.1 Hz, indanone 6-H), 7.48 (s, 1H, inda-
none 4-H), 7.56–7.59 (m, 2H, ArH), 7.78 (d, 1H, J ¼ 8.1 Hz, indanone
7-H).
2-(5-Nitrobenzimidazol-2-ylthio)-6-fluoro-2,3-dihydroinden-1-
one hydrobromide (4k): Yield 56.6%, yellow solid, m.p. 172–
174 ꢁC. 1H NMR (CDCl3, 300 MHz)
d
: 3.19 (dd, 1H, J1 ¼4.2 Hz,
2-(Benzimidazol-2-ylthio)-6-chloro-2,3-dihydroinden-1-one
J2 ¼ 18.0 Hz, indanone 3-H), 3.87 (dd, 1H, J1 ¼8.4 Hz, J2 ¼ 17.4 Hz,
indanone 3-H), 4.47 (dd, 1H, J1 ¼4.2 Hz, J2 ¼ 8.4 Hz, indanone 2-
H), 7.46 (m, 1H, ArH), 7.52 (dd, 1H, J1 ¼5.4 Hz, J2 ¼ 8.4 Hz, ArH),
7.55 (dd, 1H, J1 ¼2.4 Hz, J2 ¼ 8.6 Hz, ArH), 7.58 (d, 1H, J ¼ 8.9 Hz,
ArH), 8.18 (dd, 1H, J1 ¼ 2.1 Hz, J2 ¼ 9.0 Hz, ArH), 8.45 (d, 1H,
J ¼ 2.1 Hz, ArH).
hydrobromide (5e): Yield 61.4%, light yellow solid, m.p. 160 ꢁC. 1H
NMR (CDCl3, 300 MHz)
d
: 3.16 (dd, 1H, J1 ¼4.2 Hz, J2 ¼18.2 Hz,
indanone 3-H), 3.81 (dd,1H, J1 ¼8.4 Hz, J2 ¼ 18.2 Hz, indanone 3-H),
4.43 (dd, 1H, J1 ¼4.2 Hz, J2 ¼ 8.4 Hz, indanone 2-H), 7.22–7.28 (m,
2H, ArH), 7.45 (d, 1H, J ¼ 8.1 Hz, indanone 4-H), 7.51–7.61 (m, 2H,
ArH), 7.66 (dd, 1H, J1 ¼ 2.1 Hz, J2 ¼ 8.1 Hz, indanone 5-H), 7.83 (d,
1H, J ¼ 2.1 Hz, indanone 7-H).
2-(5-Methoxybenzimidazol-2-ylthio)- 2,3-dihydroinden-1-one hydr-
obromide (4l): Yield 47.7%, white solid, m.p. 189–192 ꢁC. 1H NMR
2-(Benzimidazol-2-ylthio)-4,6-dichloro-2,3-dihydroinden-1-one
hydrobromide (4f): Yield 51.1%, white solid, m.p. 200–203 ꢁC. 1H
(CDCl3, 300 MHz)
d
: 3.15 (dd, 1H, J1 ¼4.4 Hz, J2 ¼18.0 Hz, indanone
3-H), 3.85 (dd, 1H, J1 ¼8.2 Hz, J2 ¼ 18.0 Hz, indanone 3-H), 3.87 (s,
3H, OCH3), 4.39 (dd, 1H, J1 ¼4.5 Hz, J2 ¼ 8.2 Hz, indanone 2-H), 6.91
(dd, 1H, J1 ¼1.7 Hz, J2 ¼ 8.3 Hz, ArH), 7.08 (d, 1H, J ¼ 1.8 Hz, ArH),
7.46–7.51 (m, 3H, ArH), 7.69–7.74 (m, 1H, ArH), 7.86 (d, 1H,
J ¼ 7.5 Hz, ArH).
NMR (CDCl3, 300 MHz)
d
: 3.29 (dd, 1H, J1 ¼3.6 Hz, J2 ¼ 17.8 Hz,
indanone 3-H), 3.77 (dd, 1H, J1 ¼8.0 Hz, J2 ¼ 17.8 Hz, indanone 3-H),
4.88 (dd, 1H, J1 ¼3.6 Hz, J2 ¼ 8.0 Hz, indanone 2-H), 7.15–7.50 (m,
4H, ArH), 7.76 (d, 1H, J ¼ 1.5 Hz, indanone 5-H), 8.04 (d, 1H,
J ¼ 1.5 Hz, indanone 7-H).
2-(5-Methoxybenzimidazol-2-ylthio)-5-chloro-2,3-dihydroinden-
1-one hydrobromide (4m): Yield 58.5%, yellow solid. It was used
directly in the next step without further purification.
2-(5-Nitrobenzimidazol-2-ylthio)-2,3-dihydroinden-1-one hydro-
bromide (4g): Yield 33.8%, white solid, m.p. 232–235 ꢁC. 1H NMR
(CDCl3, 300 MHz)
d
: 3.38 (dd, 1H, J1 ¼4.8 Hz, J2 ¼ 17.6 Hz, indanone
2-(5-Methoxybenzimidazol-2-ylthio)-6-fluoro-2,3-dihydroinden-
1-one hydrobromide (4n): Yield 42.9%, white solid. It was used
directly in the next step without further purification.
3-H), 3.87 (dd, 1H, J1 ¼8.1 Hz, J2 ¼ 17.6 Hz, indanone 3-H), 4.80 (dd,
1H, J1 ¼4.8 Hz, J2 ¼ 8.1 Hz, indanone 2-H), 7.42–7.47 (m, 2H, ArH),
2-(Benzothiazol-2-ylthio)- 6-dimethoxy-2,3-dihydroinden-1-one
(4o): Yield 45.0%, white solid, m.p. 112–114 ꢁC. 1H NMR (CDCl3,
300 MHz)
d
: 3.34 (dd, 1H, J1 ¼3.9 Hz, J2 ¼ 18.0 Hz, indanone 3-H),
Table 3
3.85 (dd, 1H, J1 ¼8.1 Hz, J2 ¼18.0 Hz, indanone 3-H), 3.87 (s, 3H,
OCH3), 4.73 (dd, 1H, J1 ¼4.1 Hz, J2 ¼ 8.1 Hz, indanone 2-H), 7.25 (dd,
1H, J1 ¼2.4 Hz, J2 ¼ 8.4 Hz, ArH), 7.27 (d, 1H, J ¼ 8.4 Hz, ArH), 7.33–
7.37 (m, 2H, ArH), 7.39 (d, 1H, J ¼ 2.4 Hz, ArH), 7.66–7.78 (m, 2H,
ArH).
Cardioprotective activity of compounds 5a, 5g, 5m and 5o against ischemic–reper-
fusion injury in SD rat hearts.
Compd.a
Dosage (mg/kg)
CKb (U/ml)
Infarct sizec (%)
Ischemia–reperfusion
Cariporide
5a
5g
–
5.69 ꢀ 1.18
69.36 ꢀ 3.98
45.74 ꢀ 3.33**
42.89 ꢀ 3.43**
49.18 ꢀ 3.62*
36.16 ꢀ 2.58**
40.87 ꢀ 2.48**
42.27 ꢀ 3.41**
43.24 ꢀ 2.84**
1.0
1.0
1.0
1.0
0.5
0.25
1.0
3.53 ꢀ 0.97**
3.02 ꢀ 1.26**
4.12 ꢀ 1.34*
2.82 ꢀ 0.87**
3.34 ꢀ 1.05**
3.72 ꢀ 1.21**
3.38 ꢀ 0.96**
2-(Benzothiazol-2-ylthio)-5,6-dimethoxy-2,3-dihydroinden-1-one
(4p): Yield 37.3%, white solid, m.p. 127–129 ꢁC. 1H NMR (CDCl3,
5m
500 MHz)
d
: 3.32 (dd, 1H, J1 ¼4.0 Hz, J2 ¼17.5 Hz, indanone 3-H),
3.87 (dd, 1H, J1 ¼7.5 Hz, J2 ¼17.5 Hz, indanone 3-H), 3.93 (s, 3H,
OCH3), 3.98 (s, 3H, OCH3), 4.74 (dd, 1H, J1 ¼4.0 Hz, J2 ¼ 7.5 Hz,
indanone 2-H), 6.87 (s, 1H, indanone 4-H), 7.25 (s, 1H, indanone
7-H), 7.27–7.78 (m, 4H, ArH).
5o
*p < 0.05, **p < 0.01 compared with ischemia–reperfusion group.
a
Cariporide and the tested compounds were injected intravenously 5 min before
2-(Benzothiazol-2-ylthio)-4,5,6-trimethoxy-2,3-dihydroinden-1-
LAD occlusion.
b
one (4q): Yield 55.7%, white solid, m.p. 129.5–132 ꢁC. 1H NMR
The amount of creatine kinase (CK) was determined using a CK-NAC kit (Nanjing
Jiancheng Bioengineering Institute, Nanjing, China) and 722 grating photo-
spectrometer (Shanghai Precision & Scientific Instrument Co., Ltd., Shanghai, China).
a
(CDCl3, 500 MHz)
d
: 3.43 (dd, 1H, J1 ¼4.0 Hz, J2 ¼17.5 Hz, indanone
3-H), 4.04 (dd, 1H, J1 ¼8.0 Hz, J2 ¼ 17.5 Hz, indanone 3-H), 4.07 (s,
3H, OCH3), 4.10 (s, 3H, OCH3), 4.14 (s, 3H, OCH3), 4.87 (dd, 1H,
J1 ¼4.0 Hz, J2 ¼ 8.0 Hz, indanone 2-H), 7.42 (s, 1H, indanone 7-H),
Serum CK activity was expressed as U/ml. Values are means ꢀ SD, n ¼6 or higher.
c
Infarct size was expressed as the ratio of myocardial infarct weight to weight of
ventricle at risk. Values are means ꢀ SD, n ¼ 6 or higher.

R. Zhang et al. / European Journal of Medicinal Chemistry 44 (2009) 3771–3776
3775
Table 4
IR, MS and 1H NMR data of compounds 5a–5u.
No. IR (cmꢂ1
)
MS (m/z)a 1H NMR (
d)
5a 3458, 3068, 2912,
1663, 1607, 1547,
1271, 854, 743
5b 3454, 3003, 2962,
1673, 1622, 1591,
1330, 1266, 828, 755
5c 3429, 3128, 2951,
1668, 1626, 1545,
1350, 1093, 860, 750
5d 3362, 3146, 2972,
1678, 1618, 1545,
337.0
b,d3.08 (d, 1H, J ¼ 17.7 Hz, H-3), 3.64 (dd, 1H, J1 ¼7.2 Hz, J2 ¼17.7 Hz, H-3), 5.22 (d, 1H, J ¼ 7.2 Hz, H-2), 6.25 (bs, 6H, NH),
[M þ H]þ 7.07–7.11 (m, 2H, ArH), 7.25–7.30 (m, 3H, ArH), 7.48–7.51 (m, 2H, ArH), 7.72 (dd, 1H, J1 ¼ 2.3 Hz, J2 ¼ 8.1 Hz, H-7), 11.80 (s, 1H, NH)
397.1
b,e2.95 (dd, 1H, J ¼ 17.3 Hz, H-3), 3.56 (dd, 1H, J1 ¼7.2 Hz, J2 ¼17.3 Hz, H-3), 3.76 (s, 3H, OCH3), 3.80 (s, 3H, OCH3),
[M þ H]þ 5.19 (d, 1H, J ¼ 7.2 Hz, H-2), 6.30 (bs, 6H, NH), 6.92 (s, 1H, H-4), 7.10–7.12 (m, 2H, ArH), 7.30 (s, 1H, H-7), 7.47–7.49
(m, 2H, ArH), 12.05 (s, 1H, NH)
427.1
b,d3.28 (dd, 1H, J1 ¼6.0 Hz, J2 ¼ 17.7 Hz, H-3), 3.67 (s, 3H, OCH3), 3.70–3.87 (m, 1H, H-3), 3.77 (s, 3H, OCH3),
[M þ H]þ 3.84 (s, 3H, OCH3), 5.24 (d, 1H, J ¼ 6.0 Hz, H-2), 7.27–7.30 (m, 2H, ArH), 7.33 (s, 1H, H-7), 7.95 (bs, 5H, NH), 11.70 (s, 1H, NH)
371.1
b,d3.29 (d, 1H, J ¼ 18.3 Hz, H-3), 3.84 (dd, 1H, J1 ¼6.9 Hz, J2 ¼ 18.3 Hz, H-3), 5.26 (d, 1H, J ¼ 6.9 Hz, H-2), 7.12–7.19 (m, 2H, ArH),
[M þ H]þ 7.43–7.49 (m, 3H, ArH), 7.51 (s, 1H, H-4), 7.81 (bs, 4H, NH), 7.94 (d, 1H, J ¼ 8.1 Hz, H-7), 12.50 (s, 1H, NH)
1401, 1134, 829, 744
5e 3366, 3140, 2974, 1680, 371.1
b,d3.29 (d, 1H, J ¼ 18.0 Hz, H-3), 3.85 (dd, 1H, J1 ¼6.9 Hz, J2 ¼ 18.0 Hz, H-3), 5.26 (d, 1H, J ¼ 6.0 Hz, H-2), 7.11–7.20 (m, 3H, ArH),
1618, 1541, 1267, 1130, [M þ H]þ 7.30 (bs, 2H, NH), 7.41–7.48 (m, 3H, ArH), 7.50 (bs, 3H, NH), 8.06 (d, 1H, J ¼ 1.8 Hz, H-7), 11.50 (s, 1H, NH)
812, 742
5f 3462, 3331, 1676,
1605, 1542, 1263,
1147, 848, 736
5g 3435, 3121, 1684,
405.0
b,d3.27 (d, 1H, J ¼ 18.0 Hz, H-3), 3.84 (dd, 1H, J1 ¼6.0 Hz, J2 ¼18.0 Hz, H-3), 5.27 (d, 1H, J ¼ 6.0 Hz, H-2), 7.07–7.18 (m, 4H, ArH),
[M þ H]þ 7.48 (bs, 4H, NH), 7.62 (d, 1H, J ¼ 1.8 Hz, H-5), 8.07 (d, 1H, J ¼ 1.8 Hz, H-7), 12.50 (bs, 1H, NH)
382.1
b,d3.36 (dd, 1H, J ¼ 18.0 Hz, H-3), 3.94 (dd, 1H, J1 ¼6.6 Hz, J2 ¼18.0 Hz, H-3), 5.38 (d, 1H, J ¼ 6.6 Hz, H-2), 7.36–7.50 (m, 3H, ArH),
1618, 1587, 1524, 1336, [M þ H]þ 7.68 (d, 1H, J ¼ 8.6 Hz, H-70), 7.80 (bs, 5H, NH), 7.96 (d, 1H, J ¼ 7.6 Hz, H-7), 8.12 (dd, 1H, J1 ¼2.3 Hz, J2 ¼ 8.6 Hz, H-60),
1062, 819, 740
5h 3411, 3155, 2939,
1680, 1618, 1521,
8.41 (d, 1H, J ¼ 2.3 Hz, H-40), 12.30 (bs, 1H, NH)
472.0
b,d3.17 (d, 1H, J ¼ 17.7 Hz, H-3), 3.75 (s, 3H, OCH3), 3.80 (s, 3H, OCH3), 3.84 (s, 3H, OCH3), 3.74–3.9 (m, 1H, H-3),
[M þ H]þ 5.26 (d, 1H, J ¼ 6.3 Hz, H-2), 7.35 (s, 1H, H-7), 7.63 (d, 1H, J ¼ 8.7 Hz, H-70), 7.85 (bs, 5H, NH),
8.05 (dd, 1H, J1 ¼ 2.1 Hz, J2 ¼ 8.7 Hz, H-60), 8.39 (d, 1H, J ¼ 2.1 Hz, H-40)
1352, 1109, 820, 737
5i
5j
3416, 3172, 2941,
1680, 1619, 1520,
1336, 1109, 821, 734
3393, 3151, 1680,
1616, 1521, 1336,
1068, 820, 737
416.1
b,e3.26 (d, 1H, J ¼ 18.2 Hz, H-3), 3.86 (dd, 1H, J1 ¼6.8 Hz, J2 ¼18.1 Hz, H-3), 5.31 (d, 1H, J ¼ 6.8 Hz, H-2),
[M þ H]þ 7.42 (d, 1H, J ¼ 8.2 Hz, H-6), 7.49 (s, 1H, H-4), 7.63 (d, 1H, J ¼ 8.9 Hz, H-70), 7.70 (bs, 5H, NH), 7.90 (d, 1H, J ¼ 8.2 Hz, H-7),
8.06 (dd, 1H, J1 ¼ 2.2 Hz, J2 ¼ 8.8 Hz, H-60), 8.38 (d, 1H, J ¼ 2.2 Hz, H-40), 12.60 (bs, 1H, NH)
416.0
b,d3.30 (d, 1H, J ¼ 18.2 Hz, H-3), 3.89 (dd, 1H, J1 ¼6.8 Hz, J2 ¼ 18.0 Hz, H-3), 5.35 (d, 1H, J ¼ 6.7 Hz, H-2),
[M þ H]þ 7.42 (d, 1H, J ¼ 8.2 Hz, H-4), 7.47 (dd, 1H, J1 ¼ 2.1 Hz, J2 ¼ 8.2 Hz, H-5), 7.66 (d, 1H, J ¼ 8.9 Hz, H-70),
7.75 (bs, 5H, NH), 8.06 (s, 1H, H-7), 8.09 (dd, 1H, J1 ¼ 2.2 Hz, J2 ¼ 8.9 Hz, H-60), 8.39 (d, 1H, J ¼ 2.2 Hz, H-40),
12.80 (bs, 1H, NH)
5k 3442, 3114, 1687,
1622, 1589, 1521,
1335, 820, 742
400.1
b,d3.25 (d, 1H, J ¼ 18.0 Hz, H-3), 3.84 (dd, 1H, J1 ¼6.6 Hz, J2 ¼ 18.0 Hz, H-3), 5.34 (d, 1H, J ¼ 6.5 Hz, H-2),
[M þ H]þ 7.25 (m, 1H, H-5), 7.47 (m, 1H, H-4), 7.50 (bs, 5H, NH), 7.64 (d, 1H, J ¼ 8.9 Hz, H-70),
7.74 (dd, 1H, J1 ¼ 2.5 Hz, J2 ¼ 8.9 Hz, H-7), 8.07 (dd, 1H, J1 ¼ 2.1 Hz, J2 ¼ 8.9 Hz, H-60),
8.39 (d, 1H, J ¼ 2.1 Hz, H-40), 12.60 (bs, 1H, NH)
5l
3400, 3176, 2954,
1678, 1616, 1595,
1122, 829, 734
367.1
c,d3.15 (dd, 1H, J1 ¼4.3 Hz, J2 ¼ 18.0 Hz, H-3), 3.84 (dd, 1H, J1 ¼7.0 Hz, J2 ¼ 18.0 Hz, H-3),
[M þ H]þ 3.86 (s, 3H, OCH3), 4.40 (dd, 1H, J1 ¼4.5 Hz, J2 ¼ 7.2 Hz, H-2), 6.92 (dd, 1H, J1 ¼ 2.3 Hz, J2 ¼ 8.9 Hz, H-60),
7.08 (d, 1H, J ¼ 1.75 Hz, H-40), 7.20–7.50 (bs, 6H, NH), 7.46–7.51 (m, 3H, ArH), 7.72 (m, 1H, ArH),
7.86 (d, 1H, J ¼ 7.5 Hz, H-7), 12.40 (bs, 1H, NH)
5m 3420, 3147, 1680,
401.1
b,d3.27 (d, 1H, J ¼ 17.7 Hz, H-3), 3.76 (s, 3H, OCH3), 3.80 (d, 1H, J ¼ 17.7 Hz, H-3), 5.19 (d, 1H, J ¼ 6.3 Hz, H-2),
1620, 1151, 1070, 825
[M þ H]þ 6.78 (dd, 1H, J1 ¼ 2.4 Hz, J2 ¼ 8.7 Hz, H-60), 7.37–7.43 (m, 2H, ArH), 7.49 (s, 1H, H-4), 7.70 (bs, 5H, NH),
7.93 (m, 2H, ArH), 12.35 (bs, 1H, NH)
5n 3412, 3155, 2959,
1680, 1622, 1151,
818, 758
5o 3402, 3144, 2955,
1676, 1618, 1595,
1230, 1126, 817, 758
385.1
b,d3.24 (d, 1H, J ¼ 17.7 Hz, H-3), 3.72 (d, 1H, J ¼ 17.7 Hz, H-3), 3.78 (s, 3H, OCH3), 5.19 (d, 1H, J ¼ 6.2 Hz, H-2),
[M þ H]þ 6.80 (dd, 1H, J1 ¼ 2.4 Hz, J2 ¼ 8.8 Hz, H-60), 7.02 (s, 1H, H-40), 7.23–7.29 (m, 1H, H-5), 7.40–7.44 (m, 2H, ArH),
7.76 (dd, 1H, J1 ¼ 2.4 Hz, J2 ¼ 8.9 Hz, H-7), 7.93 (bs, 5H, NH), 12.30 (bs, 1H, NH)
384.1
b,d3.26 (d, 1H, J ¼ 17.5 Hz, H-3), 3.81 (s, 3H, OCH3), 3.89 (dd, 1H, J1 ¼6.5 Hz, J2 ¼ 17.7 Hz, H-3),
[M þ H]þ 5.43 (d, 1H, J ¼ 6.0 Hz, H-2), 7.03 (dd, 1H, J1 ¼ 2.4 Hz, J2 ¼ 8.4 Hz, H-5), 7.29 (d, 1H, J ¼ 8.4 Hz, H-4),
7.37–7.52 (m, 2H, ArH), 7.54 (d, 1H, J ¼ 2.4 Hz, H-7), 7.85 (d, 1H, J ¼ 8.0 Hz, H-40), 7.90 (bs, 5H, NH),
8.04 (d, 1H, J ¼ 7.9 Hz, H-70)
5p 3400, 3076, 1702,
1603, 1585, 1310,
1110, 832, 747
5q 3398, 3154, 2994,
1676, 1607, 1556,
1107, 1035, 839, 758
5r 3405, 3144, 2959,
1678, 1610, 1587,
1132, 993, 794, 756
5s 3398, 3144, 1678,
1607, 1567, 1236,
1130, 993, 827, 758
5t 3396, 3144, 1678,
1616, 1589, 1130,
414.1
c,d3.31 (d, 1H, J ¼ 18.0 Hz, H-3), 3.77 (dd, 1H, J1 ¼6.5 Hz, J2 ¼ 18.0 Hz, H-3), 3.86 (s, 3H, OCH3),
[M þ H]þ 3.90 (s, 3H, OCH3), 5.26 (d, 1H, J ¼ 6.0 Hz, H-2), 6.70 (s, 1H, H-4), 7.17 (s, 1H, H-7), 7.24–7.39 (m, 2H, ArH),
7.60 (bs, 5H, NH), 7.72 (d, 1H, J ¼ 7.9 Hz, H-40), 7.83 (d, 1H, J ¼ 8.1 Hz, H-70), 11.30 (bs, 1H, NH)
444.1
c,e3.27 (d, 1H, J ¼ 17.8 Hz, H-3), 3.75 (s, 3H, OCH3), 3.79 (s, 3H, OCH3), 3.84 (s, 3H, OCH3),
[M þ H]þ 3.86 (dd, 1H, J1 ¼6.7 Hz, J2 ¼17.8 Hz, H-3), 5.36 (d, 1H, J ¼ 6.0 Hz, H-2), 7.37 (s, 1H, H-7),
7.40–7.43 (m, 1H, H-50), 7.49–7.52 (m, 1H, H-60), 7.88 (d, 1H, J ¼ 8.0 Hz, H-40), 8.04 (d, 1H, J ¼ 7.9 Hz, H-70)
388.1
b,e3.37 (d, 1H, J ¼ 18.0 Hz, H-3), 3.96 (dd, 1H, J1 ¼6.7 Hz, J2 ¼ 18.0 Hz, H-3), 5.42 (d, 1H, J ¼ 6.5 Hz, H-2),
[M þ H]þ 7.38–7.52 (m, 4H, ArH), 7.76 (d, 1H, J ¼ 8.0 Hz, H-40), 7.85 (bs, 5H, NH), 7.92 (d, 1H, J ¼ 7.7 Hz, H-7),
8.03 (d, 1H, J ¼ 8.0 Hz, H-70), 11.50 (bs, 1H, NH)
388.1
b,d3.38 (d, 1H, J ¼ 18.3 Hz, H-3), 3.91 (dd, 1H, J1 ¼6.6 Hz, J2 ¼ 18.3 Hz, H-3), 5.41 (d, 1H, J ¼ 6.0 Hz, H-2),
[M þ H]þ 7.36–7.50 (m, 4H, ArH), 7.70 (bs, 5H, NH), 7.82 (d, 1H, J ¼ 8.1 Hz, H-40), 7.92 (d, 1H, J ¼ 8.1 Hz, H-70),
8.02 (d, 1H, J ¼ 7.8 Hz, H-7)
387.9
b,d3.36 (d, 1H, J ¼ 18.3 Hz, H-3), 3.89 (dd, 1H, J1 ¼6.9 Hz, J2 ¼ 18.3 Hz, H-3), 5.41 (d, 1H, J ¼ 6.0 Hz, H-2),
[M þ H]þ 7.38–7.52 (m, 4H, ArH), 7.65 (bs, 5H, NH), 7.82 (d, 1H, J ¼ 7.7 Hz, H-40), 8.03–8.05 (m, 2H, ArH)
993, 811, 758
5u 3446, 3180, 1680, 1618, 372.1
b,d3.30 (d, 1H, J ¼ 17.7 Hz, H-3), 3.89 (dd, 1H, J1 ¼7.4 Hz, J2 ¼17.8 Hz, H-3), 5.41 (d, 1H, J ¼ 6.1 Hz, H-2),
1597, 1527, 1135, 993,
814, 758
[M þ H]þ 7.26–7.33 (m, 1H, ArH), 7.38–7.51 (m, 2H, ArH), 7.60 (bs, 5H, NH), 7.75 (d, 1H, J ¼ 8.5 Hz, H-7),
7.85 (d, 1H, J ¼ 7.8 Hz, H-40), 8.05 (d, 1H, J ¼ 7.8 Hz, H-70)
a
b
c
ESI(þ), 70 V.
DMSO-d6.
CDCl3.
300 MHz.
500 MHz.
d
e

3776
R. Zhang et al. / European Journal of Medicinal Chemistry 44 (2009) 3771–3776
7.43–7.55 (m, 2H, ArH), 7.88 (d, 1H, J ¼ 8.0 Hz, ArH), 7.91 (d, 1H,
J ¼ 8.0 Hz, ArH).
4.5. Cardioprotective effects in rat model of ischemic heart
2-(Benzothiazol-2-ylthio)-4-chloro-2,3-dihydroinden-1-one (4r):
Yield 58.7%, yellow solid, m.p. 121–123 ꢁC. 1H NMR (CDCl3,
Adult male and female Sprague–Dawley rats (280–300 g) were
anesthetized with sodium pentobarbital (60 mg/kg, i.p.). Coronary
artery occlusion was produced by ligating the left anterior
descending coronary artery (LAD) for 1 h. After that, the coronary
artery was reperfused by loosing the ligature. After 2 h of reper-
fusion, the coronary artery was reoccluded and 2 ml of a 1% Evans
blue was injected via tail vein. Then the heart was removed and
blood sample was collected.
The left ventricle of the removed heart was dissected free from
other structures and sliced transversely into 1-mm thick sections.
The sections were then incubated in 1% triphenyltetrazolium
chloride for 15 min at 37 ꢁC and then fixed for 20–24 h in a 10%
formalin solution to determine the infarct size. The infarct size was
calculated by the formula as follows:
500 MHz)
d
: 3.40 (dd, 1H, J1 ¼4.5 Hz, J2 ¼18.0 Hz, indanone 3-H),
3.93 (dd, 1H, J1 ¼8.0 Hz, J2 ¼ 18.0 Hz, indanone 3-H), 4.66 (dd, 1H,
J1 ¼4.5 Hz, J2 ¼ 18.0 Hz, indanone 2-H), 7.27–7.36 (m, 2H, ArH),
7.41–7.44 (m, 1H, ArH), 7.58 (d, 1H, J ¼ 7.5 Hz, ArH), 7.65–7.75 (m,
2H, ArH), 7.78 (d, 1H, J ¼ 7.5 Hz, ArH).
2-(Benzothiazol-2-ylthio)-5-chloro-2,3-dihydroinden-1-one (4s):
Yield, 49.8%, yellow solid, m.p. 123–125 ꢁC. 1H NMR (CDCl3,
300 MHz,)
d
: 3.45 (dd, 1H, J1 ¼4.8 Hz, J2 ¼ 17.7 Hz, indanone 3-H),
3.90 (dd, 1H, J1 ¼8.1 Hz, J2 ¼17.7 Hz, indanone 3-H), 4.63 (dd, 1H,
J1 ¼4.8 Hz, J2 ¼ 8.1 Hz, indanone 2-H), 7.26–7.48 (m, 4H, ArH), 7.59
(d, 1H, J ¼ 7.6 Hz, ArH), 7.75 (d, 1H, J ¼ 7.8 Hz, ArH), 7.79 (d, 1H,
J ¼ 8.1 Hz, ArH).
2-(Benzothiazol-2-ylthio)-6-chloro-2,3-dihydroinden-1-one (4t):
Yield 42.9%, yellow solid, m.p. 128–130 ꢁC. 1H NMR (CDCl3,
Myocardial infarct size% ¼ ðthe weight of undyed myocardium=
the weight of left ventricleÞꢃ100%
300 MHz,)
d
: 3.42 (dd, 1H, J1 ¼4.5 Hz, J2 ¼ 17.4 Hz, indanone 3-H),
3.88 (dd, 1H, J1 ¼8.4 Hz, J2 ¼ 17.7 Hz, indanone 3-H), 4.64 (dd, 1H,
J1 ¼4.5 Hz, J2 ¼ 8.4 Hz, indanone 2-H), 7.26–7.38 (m, 2H, ArH), 7.42
(d, 1H, J ¼ 8.1 Hz, indanone 4-H), 7.59 (d, 1H, J ¼ 7.9 Hz, ArH), 7.62
(dd, 1H, J1 ¼ 2.1 Hz, J2 ¼ 8.1 Hz, ArH), 7.75 (d, 1H, J ¼ 7.9 Hz, ArH),
7.82 (d, 1H, J ¼ 2.1 Hz, ArH).
The blood samples were centrifuged at 3000 g for 10 min. The
supernatant serum was removed and stored in liquid nitrogen until
the biochemical analysis was performed. Creatine kinase (CK) in
serum was measured by TU-1800 (Purkinje general instrument Co.,
Ltd., China) using commercial kits (Jiancheng Bioengineering
Institute, China).
2-(Benzothiazol-2-ylthio)-6-fluoro-2,3-dihydroinden-1-one (4u):
Yield 37.4%, yellow solid, m.p. 149–152 ꢁC. 1H NMR (CDCl3,
300 MHz,)
d
: 3.41 (dd, 1H, J1 ¼4.0 Hz, J2 ¼ 17.2 Hz, indanone 3-H),
Target compounds 5a, 5g, 5m, 5o and cariporide were intrave-
nously given 5 min before reperfusion.
3.89 (dd, 1H, J1 ¼8.2 Hz, J2 ¼ 17.2 Hz, indanone 3-H), 4.66 (dd, 1H,
J1 ¼4.2 Hz, J2 ¼ 8.2 Hz, indanone 2-H), 7.28–7.51 (m, 5H, ArH), 7.60
(d, 1H, J ¼ 7.9 Hz, ArH), 7.74 (d, 1H, J ¼ 7.8 Hz, ArH).
Acknowledgment
This work is supported by the National Natural Science Foun-
dation of China (No. 30672512). The authors are grateful to Center
for Instrumental Analysis at China Pharmaceutical University for
providing 1H NMR, IR, mass spectra and elemental analysis.
4.3. General procedure for the synthesis of compounds 5
To a solution of (un)substituted 2-[benzimidazol (benzothiazol)-
2-ylthio]-2,3-dihydroinden-1-one hydrobromide (4) (2 mmol) in
methanol (30 ml) was added 5% HCl in methanol solution (0.5 mL)
at 40 ꢁC. To the resulting mixture was then added aminoguanidine
hydrochloride (0.3 g, 2.7 mmol) and heated to reflux for 2 h. After
decolorizing, the residue was purified by silica gel column chro-
matography (CHCl3/CH3OH ¼ 10:1) to afford a solid product 5.
For the physicochemical characters and spectral data of
compounds 5a–5u, see Tables 1 and 4.
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