Synthesis and anticonvulsant activity of N-(2-hydroxyethyl) cinnamamide derivatives

Article abstract of DOI:10.1016/j.ejmech.2009.02.015

A series of novel N-(2-hydroxyethyl) cinnamamide derivatives were synthesized and screened for their anticonvulsant activities by the maximal electroshock (MES) test and their neurotoxicity was evaluated by the rotarod neurotoxicity test (Tox). The MES test showed that compounds I(N-(2-hydroxyethyl) cinnamamide) and 1d ((E)-3-(3-fluorophenyl)-N-(2-hydroxyethyl)acrylamide) were found to possess better anticonvulsant activity but also had lower toxicity. In the anti-MES potency test, these compounds exhibited median effective dose (ED₅₀) of 17.7 and 17.0 mg/kg, respectively, and median toxicity dose (TD₅₀) of 154.9 and 211.1, respectively, resulting in a protective index (PI) of 8.8 and 12.4, respectively, which is much greater than the PI of the marked antiepileptic drug carbamazepine. To further investigate the effects of the anticonvulsant activity in several different models, compounds I and 1d were tested against convulsions induced by chemical substances, including pentylenetetrazole (PTZ), isoniazid, 3-mercaptopropionic acid, and thiosemicarbazide.

Full text of DOI:10.1016/j.ejmech.2009.02.015

European Journal of Medicinal Chemistry 44 (2009) 3654–3657
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and anticonvulsant activity of N-(2-hydroxyethyl) cinnamamide
derivatives
,
,b,
*
Li-Ping Guan a b, Cheng-Xi Wei b, Xian-Qing Deng b, Xin Sui b, Hu-Ri Piao b, Zhe-Shan Quan a
a Key Laboratory of Organism Functional Factors of the Changbai Mountain (Yanbian University), Ministry of Education, Yanji, Jilin 133002, PR China
b College of Pharmacy, Yanbian University, No. 121, JuZi Street, Yanji, Jilin 133000, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of novel N-(2-hydroxyethyl) cinnamamide derivatives were synthesized and screened for their
anticonvulsant activities by the maximal electroshock (MES) test and their neurotoxicity was evaluated
by the rotarod neurotoxicity test (Tox). The MES test showed that compounds I(N-(2-hydroxyethyl)
cinnamamide) and 1d ((E)-3-(3-fluorophenyl)-N-(2-hydroxyethyl)acrylamide) were found to possess
better anticonvulsant activity but also had lower toxicity. In the anti-MES potency test, these compounds
exhibited median effective dose (ED50) of 17.7 and 17.0 mg/kg, respectively, and median toxicity dose
(TD50) of 154.9 and 211.1, respectively, resulting in a protective index (PI) of 8.8 and 12.4, respectively,
which is much greater than the PI of the marked antiepileptic drug carbamazepine. To further investigate
the effects of the anticonvulsant activity in several different models, compounds I and 1d were tested
against convulsions induced by chemical substances, including pentylenetetrazole (PTZ), isoniazid,
3-mercaptopropionic acid, and thiosemicarbazide.
Received 23 July 2008
Received in revised form
1 February 2009
Accepted 12 February 2009
Available online 21 February 2009
Keywords:
Cinnamamide derivatives
Maximal electroshock (MES)
Chemical induced models
Neurotoxicity
Ó 2009 Elsevier Masson SAS. All rights reserved.
1. Introduction
new compounds were evaluated as anticonvulsant agents in
experimental epilepsy models, i.e., maximal electroshock test
Epilepsy is one of the most common neurological disorders,
affecting about 1% of the world’s population. The currently
available anticonvulsants (AEDs) are effective in reducing the
severity and number of seizures in less than 70% of patients.
Moreover, their usage is associated with undesirable side effects
ranging from cosmetic (gingival hyperplasia) to life threatening
(hepatotoxicity, megaloblastic anemia) [1–3]. Therefore,
continued search for safer and more effective AEDs is urgently
necessary.
The cinnamamide derivatives exhibit a variety of biological
activities, such as central nervous depression, sedative-hypnosis,
antidepression, muscle relaxant, local anesthesia, inhibit fungal,
and anticonvulsant activities [4–12]. In our search for new
compounds with anticonvulsant activity, N-(2-hydroxyethyl) cin-
(MES) and neurotoxicity was evaluated by using the rotarod test.
The most active compounds (I and 1d) were tested in pentyle-
netetrazole (sc-PTZ), isoniazid, 3-mercaptopropionic acid, and
thiosemicarbazide test, and the possible mechanism of action was
conjectured.
2. Results and discussion
2.1. Chemistry
Target compounds were prepared according to Scheme 1.
Compounds 1a–1p were obtained in high yield through a one-step
reaction using substituted carboxylic acid, methyl chloroformate,
triethylamine, and ethanolamine as the starting materials. The
reaction mixture was maintained at room temperature for 8–10 h.
All the compounds were identified by spectral data. In general, IR
spectra showed the C]O peak at 1658–1706, the NH stretching
vibrations at 3016–3217 cmꢀ1, and the OH stretching vibrations at
namamide (compound I) showed
a positive anticonvulsant
activity with an effective dose of 30 mg/kg in the anti-MES test. In
order to obtain compounds with better anticonvulsant activity, we
synthesized N-(2-hydroxyethyl) cinnamamide derivatives using
N-(2-hydroxyethyl) cinnamamide (I) as the lead compound. The
3307–3323 cmꢀ1
. In the nuclear magnetic resonance spectra
(1H NMR) the signals of the respective protons of the synthesized
compounds were verified on the basis of their chemical shifts,
multiplicities and coupling constants. The spectra showed the
hydrazide (NH) proton as a singlet at 5.56–6.25 ppm and the
hydroxyethyl proton (OH) at 2.21–2.83 ppm.
* Corresponding author. College of Pharmacy, Yanbian University, No. 121, JuZi
Street, Yanji, Jilin 133000, PR China. Tel.: þ86 433 2660606; fax: þ86 433 2660568.
E-mail address: zsquan@ybu.edu.cn (Z.-S. Quan).
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.02.015

L.-P. Guan et al. / European Journal of Medicinal Chemistry 44 (2009) 3654–3657
3655
O
OH
N
H
I
O
O
r.t.
ClCOOCH3
+
Et3N
H2NCH2CH2OH
+
+
OH
R
OH
R
N
8-10h
H
R:
1a: -CH=CHC6H4(p-F)
1b: -CH=CHC6H4(p-Cl)
1f: -CH=CHC6H4(o-F)
1c: -CH=CHC6H4(p-Br)
1g: -CH=CHC6H4(o-Cl)
1d: -CH=CHC6H4(m-F)
1h: -CH=CHC6H4(o-Br)
1l: -CH=CHC6H4(p-CH3)
1p: -C6H5CH2CH2
1e: -CH=CHC6H4(m-Cl)
1i: -CH=CHC6H3 (2,4-Cl2)
1m: -CH=CHC6H4(p-N(CH3)2)
1j: -CH=CHC6H4(p-CH3O) 1k: -CH=CHC6H3(3,4-OCH2O-)
1n: -C6H5 1o: -C6H5CH2
Scheme 1. Synthesis of compounds 1a–1p.
2.2. Pharmacology
Four electron-donor derivatives were also designed and
prepared, containing p-OCH3, 3,4-OCH2O–, p-CH3, and p-N(CH3)2.
The pharmacology test revealed that their activities were lower
than compound I and the activity order was 3,4-OCH2O– >
p-N(CH3)2 > p-OCH3 > p-CH3.
Compounds 1n, 1o, and 1p were obtained when the phenyl-
propylene group of compound I was substituted with phenyl group,
benzyl group, and phenethyl group, respectively. They exhibited
anti-MES effect only under the high dose of 300 mg/kg. This result
illustrated that the ethylenic linkage of compound I might be an
essential structure for the anticonvulsant activity, we reason that
the decrease in the anti-MES activity of compounds 1n, 1o, and 1p
might be due to lack of conjugation between phenyl ring and amide
linkage.
The results of preliminary (phase I) screening of compounds I
and 1a–1p are summarized in Table 1. All synthesized compounds
exhibited anticonvulsant activity, among which five compounds
1d–1f, 1k, and the lead compound I possessed anticonvulsant
activity against MES-induced seizure at the dose of 30 mg/kg, and
then eight compounds 1a–1c, 1g–1h, 1j, and 1l–1m, were active at
the dose of 100 mg/kg. The remaining four compounds 1n–1p, and
1i exhibited anti-MES effect only under the high dose of 300 mg/kg.
However, none of these compounds exhibited any potency towards
anti-MES activity at 4 h after administration.
As a result of preliminary screening, compounds I, 1a–1h, 1k,
and 1m were subjected to phase II trials for quantification of their
anticonvulsant activity (indicated by ED50) and neurotoxicity
(indicated by TD50) in mice (Table 2). Among these derivatives, the
most potent compound 1d ((E)-3-(3-fluorophenyl)-N-(2-hydrox-
yethyl)acrylamide) exhibited similar activity with ED50 value of
17.0 mg/kg to the lead compound I with ED50 value of 17.7 mg/kg in
the MES test, furthermore, it had lower neurotoxicity
(TD50 ¼ 211.1 mg/kg) than compound I (TD50 ¼ 154.9 mg/kg), and
was weaker than the marked antiepileptic drug carbamazepine
(ED50 ¼ 8.8 mg/kg). But its neurotoxicity and PI value (PI ¼ 12.4)
were superior to that of carbamazepine (TD50 ¼ 71.6 mg/kg,
PI ¼ 8.1) in the MES test. And the remaining 10 compounds 1,1a–1c,
1e–1k, and 1m exhibited comparatively weaker activity than car-
bamazepine, but these compounds possessed lower neurotoxicity
ranging from 98.3 to 304.3 mg/kg.
To further investigate the effects of the anticonvulsant activity in
several different models, compounds I and 1d were tested against
convulsions induced by chemical substances, including PTZ, isoni-
azid,
3-mercaptopropionic
acid,
and
thiosemicarbazide.
Compounds I and 1d were administered into mice i.p. at a dose of
50 mg/kg, which was slightly higher than their 3ED50 value and far
below their TD50 value. The reference drug carbamazepine was also
administered i.p. at a dose of 50 mg/kg.
In the sc-PTZ model, compounds I and 1d, and the reference
drug carbamazepine did not inhibit the clonic seizures induced by
sc-PTZ but they inhibited the tonic seizures and reduced lethality in
Table 1
Phase I evaluation of anticonvulsant activity in mice (i.p.).
Analyzing the activities of the synthesized compounds the
following structure–activity relationships (SAR) were obtained.
Generally, the anticonvulsant activity of an organic compound
might be increased remarkably after the introduction of
a halogen atom. So, some halogen substituted derivatives were
designed and synthesized in this paper. Comparison of the
halogen substituted derivatives indicated that different halogen
atoms contributed to the anticonvulsant activity in the order of
F > Cl > Br; the introduction of F atom on the benzyl ring led to
stronger activity.
Comparing the derivatives with different F-substitution
positions on the benzyl ring, their activity order was m-F > o-F > p-F.
m-F substituted derivative 1d ((E)-3-(3-fluorophenyl)-N-(2-hydr
oxyethyl)acrylamide) was the strongest in all tested compounds
with ED50 value of 17.0 mg/kg, and exhibited the lowest neurotox-
icity with TD50 value of 211.1 mg/kg, a higher protective index
(PI ¼ 12.4) was achieved than the reference drug carbamazepine,
and activity order of the Cl- and Br atom-substituted derivatives was
m-Cl > o-Cl > p-Cl > 2,4-Cl2, and o-Br > p-Br.
Compound
R
Dosage (mg/kg)
MESa
0.5 h
4 h
I
–CH]CHC6H5
30
100
100
100
30
4/5
5/5
4/5
2/5
5/5
4/5
2/5
5/5
3/5
2/5
2/5
2/5
1/5
4/5
2/5
2/5
1/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
1a
1b
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
1m
1n
1o
1p
–CH]CHC6H4 (p-F)
–CH]CHC6H4 (p-Cl)
–CH]CHC6H4 (p-Br)
–CH]CHC6H4 (m-F)
–CH]CHC6H4 (m-Cl)
–CH]CHC6H4 (o-F)
–CH]CHC6H4 (o-Cl)
–CH]CHC6H4 (o-Br)
–CH]CHC6H3 (2,4-Cl2)
–CH]CHC6H4 (p-CH3O)
–CH]CHC6H3 (3,4-OCH2O–)
–CH]CHC6H4 (p-CH3)
–CH]CHC6H4 (p-N(CH3)2)
–C6H5
30
30
100
100
300
100
30
100
100
300
300
300
–C6H5CH2
–C6H5CH2CH2
a
Maximal electroshock test (number of animals protected/number of animals
tested), the number of mice is five.

3656
L.-P. Guan et al. / European Journal of Medicinal Chemistry 44 (2009) 3654–3657
Table 2
Table 4
Phase II quantitative anticonvulsant data in mice (test drug administered i.p.).
Effect of compounds on isoniazid-induced convulsion in mice.
Compound
Rotarod toxicity
Compound
Doses
Test time Clonic seizures Tonic seizures Lethality
(mg/kg) (h)
(%)
(%)
(%)
a
b
MES, ED50
TD50
PIc (TD50/ED50
)
DMSO:
CMC-Na
0.5
100
100
0
I
1a
1b
1c
1d
1e
1f
1g
17.7 (14.8–21.2)d
45.6 (37.9–54.8)
73.4 (61.0–88.1)
76.0 (63.2–91.4)
17.0 (14.1–20.4)
25.0 (20.8–30.0)
35.3 (29.4–42.3)
59.0 (49.0–70.8)
68.2 (56.9–81.8)
32.4 (27.0–38.8)
66.1 (55.1–79.3)
8.8 (5.5–14.1)
154.9 (137.6–174.4)
98.3 (84.2–114.7)
98.4 (64.6–148.7)
98.3 (84.2–114.7)
211.1 (175.6–253.8)
126.8 (105.5–152.4)
219.1 (182.2–263.4)
152.1 (126.5–182.9)
228.2 (203.4–256.0)
105.4 (87.7–126.7)
304.3 (271.2–341.4)
71.6 (45.9–135)
8.8
2.2
1.3
1.3
12.4
5.1
6.2
2.6
3.3
3.3
4.6
8.1
Carbamazepine 50
0.5
0.5
0.5
50
100
100
0
70
80
0
20
20
I
1e
50
50
decreased GABA level in the brain [16]. Compounds I and 1d
showed moderate antagonism to 3-mercaptopropionic acid-
induced seizures and thiosemicarbazide-induced seizures, sug-
gesting that they might activate GAD or inhibit aminotransferase
(GABA-T) in the brain.
In conclusion, the results of this study demonstrated that
N-(2-hydroxyethyl) cinnamamide derivatives have potent anti-
convulsant activity. Especially, compounds I and 1d showed better
anticonvulsant activity but also much lower toxicity than
a benchmark marketed drug. In addition, compounds I and 1d
demonstrated antagonistic activity against seizures induced by
3-mercaptopropionic acid and thiosemicarbazide, but failed to
control those induced by PTZ and isoniazid. These experiments
suggested that compounds I and 1d might activate glutamate
decarboxylase (GAD) or inhibit GABA alpha-oxogluturate amino-
transferase (GABA-T).
1h
1k
1m
Carbamazepine
a
ED50 – median effective dose required to assure anticonvulsant protection in
50% animals, the number of mice is ten.
b
TD50 – median toxic dose eliciting minimal neurological toxicity in 50% animals.
PI – protective index (TD50/ED50).
95% Confidence limits given in parentheses.
c
d
significant degrees (Table 3). In the isoniazid model, carbamazepine
inhibited the clonic seizures, tonic seizures and death induced by
isoniazid at the rate of 50%, 100% and 100%, respectively; and
compounds I and 1d did not affect the clonic seizures and showed
partial inhibition of the tonic seizures and death induced by
isoniazid (Table 4). PTZ and isoniazid have been reported to
produce seizures by inhibiting
g-aminobutyric acid (GABA)
neurotransmission [13,14]. GABA is the main inhibitory neuro-
transmitter substance in the brain, and is widely implicated in
epilepsy. Inhibition of GABAergic neurotransmission or activity has
been shown to promote and facilitate seizures [15], while
enhancement of GABAergic neurotransmission is known to inhibit
or attenuate seizures. The findings of the present study suggest that
the newly synthesized compounds I and 1d might have not
inhibited or attenuated PTZ-induced and isoniazid-induced
seizures in mice by enhancing GABAergic neurotransmission.
In the 3-mercaptopropionic acid-induced seizure model, car-
bamazepine inhibited the clonic seizures, tonic seizures and death
at the rate of 0%, 100%, and 100%, respectively. In comparison,
compounds I and 1d showed the effect pattern similar to that of
carbamazepine in inhibiting the clonic seizures, and showed partial
inhibition of the tonic seizures and death induced by 3-mercapto-
propionic acid. Compound I showed inhibition at the rate of 0%, 90%
and 90%, respectively, and compound 1d showed inhibition of at
the rate of 0%, 70% and 50%, respectively (Table 5). In the thio-
semicarbazide-induced convulsion, the effect pattern is similar to
that of the 3-mercaptopropionic acid-induced seizure model
where, compared to the reference drug, compound I showed
inhibition at the rate of 0%, 60% and 70%, respectively of the clonic
seizures, tonic seizures and death. And compound 1d showed
inhibition at the rate of 0%, 50% and 60%, respectively (Table 6).
3-Mercaptopropionic acid and thiosemicarbazide were competitive
inhibitors of GABA synthesis enzyme glutamate decarboxylase
(GAD), and they inhibit the synthesis of GABA resulting in
3. Experimental section
3.1. Chemistry
Melting points were determined in open capillary tubes and
were uncorrected. IR spectra were recorded (in KBr) on an FT-
IR1730 (Bruker, Switzerland), 1H NMR spectra were measured on an
AV-300 (Bruker, Switzerland), and all chemical shifts were given in
ppm relative to tetramethylsilane. Mass spectra were measured on
an HP1100LC (Agilent Technologies, USA). The major chemicals
were purchased from Aldrich Chemical Corporation. All other
chemicals were of analytical grade.
3.2. General procedure for the preparation of I, 1a–1p
In a three-necked round-bottomed flask containing substituted
carboxylic acid 2 g (0.05 mol), 50 ml dichloromethane and trie-
thylamine (0.1 mol), methyl chloroformate (0.1 mol) was added
dropwise slowly under an ice bath with stirring, the mixture was
stirred 2 h at room temperature. Then ethanolamine (0.1 mol) was
added dropwise slowly under an ice bath with stirring, the mixture
was stirred 6–8 h at room temperature. The solvents were removed
under reduced pressure. The residue was poured into 100 ml ice
water and stirred for 10 min. The solid obtained after filtration was
recrystallized in water to afford a white solid.
Table 3
Table 5
Effect of compounds on PTZ-induced convulsion in mice.
Effect of compounds on 3-mercaptopropionic acid-induced convulsion in mice.
Compound
Doses
Test time Clonic seizures Tonic seizures Lethality
Compound
Doses
Test time Clonic seizures Tonic seizures Lethality
(mg/kg) (h)
(%)
(%)
(%)
(mg/kg) (h)
(%)
(%)
(%)
DMSO:
–
0.5
100
100
0
DMSO:
0.5
100
100
80
CMC-Na
CMC-Na
Carbamazepine 50
0.5
0.5
0.5
100
100
100
0
20
40
10
10
20
Carbamazepine 50
0.5
0.5
0.5
100
100
100
0
10
30
0
10
50
I
50
50
I
50
50
1d
1d

L.-P. Guan et al. / European Journal of Medicinal Chemistry 44 (2009) 3654–3657
3657
Table 6
number of clonic and tonic seizures as well as the number of
deaths was noted.
Effect of compounds on thiosemicarbazide-induced convulsion in mice.
Compound
Doses
Test time
Clonic seizures Tonic seizures Lethality
(mg/kg) (h)
(%)
(%)
(%)
3.4.3. Isoniazid-induced seizures test [21]
DMSO:
CMC-Na
Carbamazepine 50
I
2.5
100
100
100
At 30 min after the administration of the compounds at various
doses, the animals were given an i.p. dose of isoniazid (250 mg/kg),
a dose at which 100% of the animals showed convulsive reactions.
The mice were placed in individual cages and observed for 1 h. The
dose which prevented 50% of the treated animals from tonic
convulsions (ED50) was calculated.
2.5
2.5
2.5
100
100
100
0
40
50
20
30
40
50
50
1d
3.3. Analytical data for compounds I, 1d, and 1k
3.4.4. 3-Mercaptopropionic acid-induced seizures test [22]
At 30 min after the administration of the compounds, 60 mg/kg
of 3-mercaptopropionic acid in saline solution was injected sc.
Latency and duration of convulsions as well as latency and
percentage of lethality were recorded during the 1 h following 3-
mercaptopropionic acid administration. The dose which prevented
50% of the treated animals from tonic convulsions (ED50) was
calculated.
3.3.1. N-(2-Hydroxyethyl) cinnamamide (I)
Yield: 82%; m.p.:100–102 ꢁC.1H NMR (CDCl3):
d
2.61 (s,1H, –OH),
3.54 (t, 2H, –CH2OH), 3.80 (t, 2H, –CH2NHCO), 6.19 (s,1H, –NH), 6.47
(dd,1H, J ¼ 15 Hz, ]CHCO), 7.66 (dd,1H, J ¼ 15 Hz, CH]C), 7.34–7.47
(m, 5H, –C6H5). MS m/z: 192 (M þ 1). Anal. Calcd for C11H13NO2: C,
69.09; H, 6.85; N, 7.32. Found: C, 68.91; H, 6.72; N, 7.20.
3.3.2. (E)-3-(3-Fluorophenyl)-N-(2-hydroxyethyl)acrylamide (1d)
3.4.5. Thiosemicarbazide-induced seizures test [23]
Yield: 78%; m.p.:98–100 ꢁC. 1H NMR (CDCl3):
d 2.19 (s, 1H, –OH),
At 30 min after the administration of compounds, the animals
were given an i.p. dose of thiosemicarbazide (50 mg/kg). The mice
were placed in individual cages and observed for 2.5 h. The time of
onset of the seizure, the number of clonic seizures, tonic seizures
and the lethality were recorded.
3.57 (t, 2H, –CH2OH), 3.81 (t, 2H, –CH2NHCO), 6.25 (s, 1H, –NH),
6.45 (dd, 1H, J ¼ 15 Hz, ]CHCO), 7.63 (dd, 1H, J ¼ 15 Hz, CH]C),
7.05–7.37 (m, 5H, –C6H5). MS m/z: 210 (M þ 1). Anal. Calcd for
C11H12FNO2: C, 63.15; H, 5.78; N, 6.69. Found: C, 63.02; H, 5.65; N,
6.58.
Acknowledgment
3.3.3. (E)-3-(Benzo[d][1,3]dioxol-5-yl)-N-(2-
hydroxyethyl)acrylamide (1k)
This work was supported by the National Natural Science
Foundation of China (No. 30460151 and No. 30760290) and
Important Item Foundation of Ministry of Education, PR China (No.
20070422029).
Yield: 85%; m.p.: 96–99 ꢁC. 1H NMR (CDCl3):
d 2.18 (s, 2H,
–OCH2O–), 2.57 (s, 1H, –OH), 3.57 (t, 2H, –CH2OH), 3.83 (t, 2H,
–CH2NHCO), 6.21 (s, 1H, –NH), 6.33 (dd,1H, J ¼ 15 Hz, ]CHCO), 7.63
(dd, 1H, J ¼ 15 Hz, CH]C), 6.89–7.46 (m, 5H, –C6H5). MS m/z: 236
(M þ 1). Anal. Calcd for C12H13NO4: C, 61.27; H, 5.57; N, 5.95. Found:
C, 61.15; H, 5.49; N, 5.87.
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3.4. Pharmacology
All compounds were tested for anticonvulsant activity with
Kunming mice in the 18–25 g weight range purchased from the
Laboratory of Animal Research, College of Pharmacy, Yanbian
University. The tested compounds were prepared as a suspension
in a mixture of 1:19 (vol/vol) dimethylsulfoxide/saline (0.9% NaCl)
containing 0.5% methylcellulose. All compounds were tested by
the MES test; otherwise, compounds I and 1d were tested by sc-
PTZ, isoniazid, 3-mercaptopropionic acid, and thiosemicarbazide
tests.
3.4.1. Anticonvulsant effects in the maximal electroshock seizure
(MES) test [17,18]
[13] R. Okada, N. Negishi, H. Nagaya, Brain Res. 480 (1989) 383–387.
[14] R.W. Olsen, J. Neurochem. 37 (1981) 1–13.
Seizures were elicited with a 60 Hz alternating current of 50 mA
intensity in mice. The current was applied via corneal electrodes for
0.2 s. Protection against the spread of MES-induced seizures was
defined as the abolition of the hind leg and tonic maximal exten-
sion component of the seizure. At 30 min after the administration
of the compounds, the activities were evaluated in MES test.
[15] K. Gale, Epilepsia 33 (1992) S3–S12.
[16] W. Loscher, Biochem. Pharmacol. 28 (1979) 1397–1407.
[17] J.B. Hester Jr., P. Von Voigtlander, J. Med. Chem. 22 (1979) 1390–1398.
[18] J.B. Hester Jr., A.D. Rudzik, P. Von Voigtlander, J. Med. Chem. 23 (1980)
402–405.
[19] R.L. Krall, J.K. Penry, B.G. White, H.J. Kupferberg, E.A. Swinyard, Epilepsia 9
(1978) 409–428.
[20] R.J. Porter, J.J. Cereghino, G.D. Gladding, B.J. Hessie, H.J. Kupferberg, B. Scoville,
B.G. White, Cleve. Clin. Q. 51 (1984) 293–305.
[21] R. Bernasconi, M. Klein, P. Martin, P. Christen, T. Hafner, C. Portet, M. Schmutz,
J. Neural. Transm. 72 (1988) 213–233.
[22] A. Arnoldi, A. Bonsignori, P. Melloni, L. Merlini, M. Luisa Quisadri, A.C. Rossi,
M. Valsecchi, J. Med. Chem. 33 (1990) 2865–2869.
3.4.2. sc-PTZ-induced seizures [19,20]
At 30 min after the administration of the test compounds,
85 mg/kg PTZ dissolved in saline was administered sc. The
animals placed in individual cages and observed for 30 min. The
[23] W. Lo¨scher, D. Schmidt, Epilepsy Res. 2 (1988) 145–181.