Synthesis and Anticonvulsant Activity of 1-(2-(8-(benzyloxy)quinolin-2-yl)-1-butyrylcyclopropyl)-3-Substituted Urea Derivatives

Article abstract of DOI:10.1111/j.1747-0285.2012.01352.x

In the present study on the development of new anticonvulsants, 16 new1-(2-(8-(benzyloxy)quinolin-2-yl)-1-butyrylcyclopropyl)-3-substituted urea derivatives were synthesized and tested for anticonvulsant activity using the maximal electroshock seizure, su

Full text of DOI:10.1111/j.1747-0285.2012.01352.x

ª 2012 John Wiley & Sons A/S
doi: 10.1111/j.1747-0285.2012.01352.x
Chem Biol Drug Des 2012; 79: 771–779
Research Article
Synthesis and Anticonvulsant Activity of
1-(2-(8-(benzyloxy)quinolin-2-yl)-1-
butyrylcyclopropyl)-3-Substituted Urea
Derivatives
Xianran He1, Min Zhong2, Jin Yang3,
Zhongyuan Wu1, Yuling Xiao1, Hao Guo1
and Xianming Hu1,*
Quinoline derivatives show several beneficial heterogenous and var-
ied pharmacological properties, for example, antibacterial (4), immu-
nosuppressive (5), analgesic (6), vasorelaxing (7), antiplasmodial (8),
anticancer (9), PDE4 inhibitory (10), and anticonvulsant (11,12) activi-
ties. On the other hand, thioureas and ureas group belong to bio-
logically highly active skeletons. Various urea and thiourea
derivatives were extensively studied for their antitubercular (13),
antifungal (14), anti-HIV (15), and antihypertensive activities (16,17).
Recently, compounds containing urea group have emerged as struc-
turally novel anticonvulsants (18). It has been hypothesized that thi-
oureas and ureas displaying anticonvulsant activity interact at
locations on the putative binding site designed as aryl binding site,
a hydrogen-bonding domain, and an auxiliary aryl or other hydro-
phobic binding site (19).
1State Key Laboratory of Virology, Ministry of Education Laboratory
of Combinatorial Biosynthesis and Drug Discovery, Wuhan University
School of Pharmaceutical Science, Wuhan 430071, China
2Hubei Research Institute of Chemistry, Wuhan 430074, China
3Hubei University for Nationalities School of Medicine, Enshi
445000, Hubei, China
*Corresponding author: Xianming Hu, hexianran@yahoo.com.cn
In the present study on the development of new
anticonvulsants, 16 new1-(2-(8-(benzyloxy)quino-
lin-2-yl)-1-butyrylcyclopropyl)-3-substituted
urea
derivatives were synthesized and tested for anti-
convulsant activity using the maximal electro-
shock seizure, subcutaneous pentylenetetrazole
screens, which are the most widely employed sei-
zure models for early identification of candidate
anticonvulsants. Their neurotoxicity was deter-
mined by applying the rotorod test. Three com-
pounds 7a, 7e, and 7m showed promising
anticonvulsant activities in both models employed
for anticonvulsant evaluation. The most active
compound 7e showed the maximal electroshock
seizure-induced seizures with ED50 value of
14.3 mg ⁄ kg and TD50 value of 434 mg/kg after
intraperitoneal injection to mice, which provided
Above these facts and in continuation of our research program on
design and synthesis of new anticonvulsant agents, the urea phar-
macophore has been attached to 2-propane-quinoline ring and to
an aryl or alkyl group in order to develop new potent and safe
AEDs. We synthesized and comparatively evaluated the anticonvul-
sant activity and neurotoxicity of 16 new 1-(2-(8-(benzyloxy)quinolin-
2-yl)-1-butyrylcyclopropyl)-3-substituted urea derivatives. Compounds
7a, 7e, and 7m were quantitatively evaluated for its anticonvul-
sant activity (ED50) and neurotoxicity (TD50).
Materials and Methods
compound 7e with a protective index (TD50/ED50
of 30.3 in the maximal electroshock seizure test.
)
All chemicals and solvents were purchased from Aldrich, or Fluka
(St. Louis, MO, USA). Solvents and reagents were dried and purified
according to the literature methods. Melting points were uncor-
rected and measured on an XT-4 apparatus.1H and 13C NMR spectra
were obtained on a Bruker AV400 apparatus in DMSO-d6 and CDCl3
with TMS as internal standard. The elemental analysis (C, H, N)
data were obtained from a VarioEL III (German) elemental analyzer.
The mass spectra (MS) were recorded on AMD-604 Mass Spec-
trometer operating at 70 eV.
Key words: 1-(2-(8-(benzyloxy)quinolin-2-yl)-1-butyrylcyclopropyl)-3-
substituted urea derivatives, anticonvulsant activity, maximal electro-
shock seizure test, subcutaneous pentylenetetrazole test
Received 14 June 2011, revised 7 January 2012 and accepted for publi-
cation 8 January 2012
Epilepsy is a common neurological disorder characterized by recur-
rent seizures that affect about 1% of the world's population (1,2).
In spite of the apparent success of the current discovery process, a
significant need persists for more effective and less toxic anti-epi-
leptic drugs (AEDs). Besides, about 30% of epileptic patients are
not seizure-free from current AEDs (3).
Synthesis of 8-(benzyloxy)-2-methylquinoline (1)
To a mixture of 2-methylquinoline-8-ol (8.00 g, 50.3 mmol) and
Na2CO3 (6.30 g, 59.4 mmol) in ethanol (100 mL), a solution of ben-
zyl bromide (10.1 g, 59.4 mmol) in acetone (20 mL) was added. In
the dark, the reaction mixture was stirred at r.t. for 12 h. After
filtration, the resulting solution was evaporated. Short-column
771

He et al.
chromatography on silica gel with chloroform and recrystallization
from PE–EtOAc (6:1) gave 1 (11.22 g, 90%) as a white solid: 1H
NMR (400 MHz, CDCl3): d 2.81 (s, 3H, CH3), 5.46 (s, 2H, PhCH2O),
6.98 (d, 1H, J = 7.60 Hz), 7.26–7.52 (m, 6H), 7.54 (d, 2 H,
J = 7.20 Hz), 8.03(d, 1H, J = 8.40 Hz).13C NMR (100 MHz, CDCl3): d
24.82, 70.91, 110.83, 118.72, 123.41, 126.45, 126.88, 127.12,
127.95, 128.67, 136.64, 137.27, 139.54, 154.34, 157.36.
suspension was cooled to 15 ꢀC, and to this mixture was added
with stirring a solution of 16.22 g (0.04 mol) of 3 in 25 mL of
DMSO in one portion. The stirring was continued for 10 min at
15 ꢀC, overnight at room temperature and 4 h at 50–60 ꢀC. After it
was cooled and 400 mL of ice-water was added to it, the mixture
was extracted with ether, and the combined ether fractions were
washed with brine, dried over anhydrous sodium sulfate (Na2SO4),
and evaporated to give a pale yellow oil. The residue was purified
via a chromatography eluting with 6:1, hexanes ⁄ EtOAc to give 4
1
Synthesis of 8-(benzyloxy)quinoline-2-
(15.0 g, 65%) as a colorless oil: H NMR (400 MHz, CDCl3): d 0.74
carbaldehyde (2)
(t, 3H, J = 7.12 Hz, CH3), 1.28 (t, 3H, J = 7.12 Hz, CH3), 1.89–1.93
(m, 1H, Cpr-H), 2.68–2.70 (m, 1H, Cpr-H), 3.30–3.35(m, 1H, Cpr-H),
3.83 (q, 2H, J = 7.12 Hz, CH2), 4.23 (q, 2H, J = 7.12Hz, CH2), 5.34
(s, 1H, PhCH2O), 7.07 (d, 1H, J = 8.48 Hz), 7.25–7.45 (m, 6H), 7.58
(d, 2H, J = 7.56 Hz), 8.04 (d, 1H, J = 8.44 Hz). 13C NMR (100 MHz,
CDCl3): d 12.45, 13.01, 19.11, 32.45, 35.94, 59.96, 60.79, 70.05,
110.65, 119.08, 121.35, 125.09, 125.71, 125.98, 126.57, 127.39,
134.96, 136.27, 139.00, 153.17, 153.64, 165.41, 168.80.
8-(Benzyloxy)-2-methylquinoline (9.20 g, 0.035 mmol) was added to
a dry flask under nitrogen, followed by dry dioxane (300 mL) and
molecular sieves (4 ꢀ, 60 mg). Selenium dioxide (4.65 g,
0.042 mmol) was added, and the reaction was stirred at 95 ꢀC for
12 h and then cooled to room temperature. The reaction mixture
was filtered through celite to remove the black residue and molecu-
lar sieves. The dioxane was removed by rotary evaporation, and the
yellow oil was redissolved in ethyl acetate (500 mL), washed with
brine (100 mL), water (100 mL), saturated potassium carbonate solu-
tion (100 mL), and dried (MgSO4). Rotary evaporation of the solvent
and recrystallization from PE–EtOAc (4:1) give 2 (9.02 g, 98%) as a
white solid: 1H NMR (400 MHz, CDCl3): d 5.46 (s, 2 H, PhCH2O),
7.16 (d, 1H, J = 8.40 Hz), 7.32–7.56 (m, 6H), 8.07 (d, 2H,
J = 8.44 Hz), 8.28 (d, 1H, J = 8.56 Hz), 10.32 (s, 1H, CHO). 13C
NMR (100 MHz, CDCl3): d 71.32, 111.88, 118.43, 123.32, 126.71,
126.89, 127.54, 128.33, 128.76, 136.54, 138.43, 139.90, 154.33,
155.78, 193.23.
2-(8-(benzyloxy)quinolin-2-yl)-1-
(ethoxycarbonyl)cyclopropanecarboxylic acid
(5)
To a solution of compound 4 (10 mmol) in anhydrous ethanol
(50 mL) was added 1 N sodium hydroxide (25 mL, 1.1 equiv,
25 mmol), and the resulting mixture was stirred art room tempera-
ture for 12 h. EtOH was removed under reduced pressure, water
was added to the residue, and the mixture was acidified by means
of a saturated KHSO4 and extracted with ethyl acetate (3 · 30 mL).
The combined extracts were dried over Na2SO4 and evaporated to
give products 5 as a colorless oil: 1H NMR (400 MHz, CDCl3): d
0.51 (t, 3H, J = 7.12 Hz, CH3), 2.02–2.06(m, 1H, Cpr-H), 2.43–2.46
(m, 1H, Cpr-H), 3.67 (q, 2H, J = 7.12 Hz, CH2), 3.74–3.80 (m, 1H,
Cpr-H), 5.32 (s, 1H, PhCH2O), 7.1 1(d, 1H, J = 7.16 Hz), 7.33–7.55
(m, 6H), 7.54 (d, 2H, J = 7.32 Hz), 8.09 (d, 1H, J = 8.48 Hz). 13C
NMR (100 MHz, CDCl3): /d 13.16, 19.02, 31.95, 37.24, 60.15, 69.95,
111.41, 119.90, 122.65, 126.10, 126.98, 127.47, 127.94, 128.26,
136.00, 137.43, 139.19, 153.55, 154.82, 165.97, 170.63.
Synthesis of diethyl 2-((8-(benzyloxy)quinoline-
2-yl)methylene)malonate (3)
To a solution of compound 2 (10.0 g, 93.0 mmol) and diethyl malo-
nate (17.94 g, 112.0 mmol), in toluene (200 mL) was added piperi-
dine (7.95 g, 93 mmol) followed by acetic acid (5.61 g,
93 mmol).The reaction mixture was heated to reflux for 20 h, and
the distillate was collected in a Dean–Stark apparatus. It was
cooled to room temperature and concentrated in vacuo. The dark
brown residue was dissolved in ethyl acetate and washed succes-
sively with NaHCO3 (saturated) and NaCl (saturated), dried over
Na2SO4, and concentrated in vacuo. The residue was purified via a
flash chromatography eluting with 4:1, hexanes: EtOAc to give 3
General procedure for the synthesis of
compounds (7a–7p)
1
(15.0 g, 65%) as a white solid: H NMR (400 MHz, CDCl3): d 1.04
Compound 5 (10 mmol) was dissolved in dry THF (30 mL) and
cooled to )15 ꢀC. After the addition of EtOCOCl (11 mmol) and
Et3N (12 mmol), the mixture was stirred for 20 min. A solution of
NaN3 (25 mmol) in H2O was added and stirred for 1 h at )10 ꢀC.
The solution was then diluted with H2O and extracted with EtOAc.
The organic layers were washed with brine, dried over Na2SO4, and
concentrated under reduced pressure to give crude acyl azide. This
crude acyl azide could be further purified by a flash column chroma-
tography (PE-EtOAc, 4:1, Rf = 0.7). Purified acyl azide was dissolved
in toluene (30 mL), and the resulting solution was heated to 75 ꢀC
under stirring. After gas evolution had stopped, toluene was
removed under reduced pressure to afford a-carboethoxyisocyanate
6 as clear oil. This a-carboethoxyisocyanate 6 was directly used in
the next step without further purification. Various amines (10 mmol)
were added to a stirred suspension of isocyanate 6 in appropriate
solvent (40 mL) at r.t. The solvent was removed under reduced
(t, 3H, J = 7.12 Hz, CH3), 1.25 (t, 3H, J = 7.12 Hz, CH3), 4.11 (q, 2H,
J = 7.12 Hz, CH2), 4.23 (q, 2H, J = 7.12 Hz, CH2), 5.27 (s, 1H,
PhCH2O), 6.96 (d, 1H, J = 8.42 Hz), 7.21–7.49 (m, 8H), 7.76 (s, 1H,
CH=C), 8.03 (d, 1H, J = 8.44 Hz). 13C NMR (100 MHz, CDCl3): d
13.99, 14.11, 61.40, 61.76, 71.01, 110.74, 119.71, 123.34, 127.66,
127.95, 128.62, 129.33, 129.76, 136.65, 139.84, 140.63, 150.09,
154.95, 164.11, 166.14.
Synthesis of diethyl 2-(8-(benzyloxy)quinoline-2-
yl)cyclopropane-1,1-dicarboxylate (4)
To a stirred suspension of sodium hydride (2.12 g, 0.044 mol, 57%
in oil dispersion) in dry dimethyl sulfoxide (DMSO) (100 mL) under
nitrogen was added of trimethylsulfoxonium iodide (9.66 g,
0.044 mol) in a single portion. After frothing ceased, the gray-white
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Chem Biol Drug Des 2012; 79: 771–779

Synthesis and Anticonvulsant Activity of Urea Derivatives
pressure when the reaction was completed (detected by TLC) and
the products 7 were purified by a column chromatography.
PhCH2O), 5.86 (br s, 1H, NH), 7.07–7.09 (m, 1H), 7.29–7.43 (m,
6H), 7.56 (d, 1H, J = 7.44 Hz), 8.03 (d, 1H, J = 8.48 Hz). 13C-
NMR (CDCl3, 100 Hz), d 13.14, 20.11, 22.58, 22.77, 34.94, 38.17,
41.87, 60.86, 70.93, 111.06, 119.92, 122.72, 126.40, 127.09,
127.75, 128.30, 128.49, 136.03, 137.16, 139.87, 154.08, 155.28,
161.95, 170.99. MS m ⁄ z 448.5 (M+ + 1). Anal. Calcd. For
C26H29N3O4: C, 69.78; H, 6.53; N, 9.39. Found: C, 69.88; H, 6.47;
N, 9.27.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-
ureidocyclopropanecarboxylate (7a)
1
Mp: 151–153 ꢀC, yield = 85%. H-NMR (CDCl3, 400 MHz), d0.51 (t,
3H, J = 7.12 Hz, CH3), 2.28–2.32 (m, 1H, Cpr-CH), 2.58–2.61 (m, 1H,
Cpr-CH), 3.53 (q, 2H, J = 7.12 Hz, CH2), 3.71–3.76 (m, 1H, Cpr-CH),
5.01–5.13 (m, 1H, NH2), 5.39 (s, 2H, PhCH2O), 5.66 (br s, 1H, NH),
7.07–7.09 (m, 1H), 7.30–7.44 (m, 6H), 7.56 (d, 2H, J = 7.40 Hz), 8.04
(d, 1H, J = 8.44 Hz). 13C-NMR (CDCl3, 100 Hz), d 13.07, 18.34,
33.41, 38.37, 60.41, 69.98, 111.35, 119.86, 122.49, 126.16, 127.10,
127.52, 127.89, 128.28, 135.89, 137.40, 139.25, 153.58, 154.99,
159.83, 172.02. MS m ⁄ z 406.4 (M+ + 1). Anal. Calcd. For
C23H23N3O4: C, 68.13; H, 5.72; N, 10.36. Found: C, 68.21; H, 5.81;
N, 10.47.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-(1-
hydroxybutan-2-yl)ureido)cyclopropane
carboxylate (7e)
1
Mp: 148–150 ꢀC, yield = 85%. H-NMR (CDCl3, 400 MHz), d 0.52 (t,
3H, J = 7.12 Hz, CH3), 1.02 (t, 3H, J = 7.44 Hz, CH3), 1.55–1.71 (m,
2H, CH2), 2.25–2.28 (m, 1H, Cpr-CH), 2.52–2.55 (m, 1H, Cpr-CH),
3.32 (br s, 1H, OH), 3.52–3.54 (m, 2H, CH2), 3.58–3.63 (m, 1H, CH),
3.70–3.75 (m, 2H, CH2), 3.90–3.95 (m, 1H, Cpr-CH), 5.33 (br s, 1H,
NH), 5.38 (s, 2H, PhCH2O), 5.89 (br s, 1H, NH), 7.08–7.09 (m, 1H),
7.30–7.44 (m, 6H), 7.55 (d, 1H, J = 7.40 Hz), 8.05 (d, 1H,
J = 8.44 Hz). 13C-NMR (CDCl3, 100 Hz), d 13.13, 13.81, 20.24,
19.69, 31.47, 34.89, 38.41, 39.80, 60.89, 71.02, 111.27, 119.95,
122.71, 126.37, 127.05, 127.71, 128.32, 128.48, 136.00, 137.25,
139.99, 154.16, 155.23, 160.83, 171.08. MS m ⁄ z 478.4 (M+ + 1).
Anal. Calcd. For C27H31N3O5: C, 67.91; H, 6.54; N, 8.80. Found: C,
67.85; H, 6.44; N, 8.63.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-
methylureido)cyclopropanecarboxylate (7b)
1
Mp: 134–136 ꢀC, yield = 83%. H-NMR (CDCl3, 400 MHz), d 0.50 (t,
3H, J = 7.16 Hz, CH3), 2.30–2.33 (m, 1H, Cpr-CH), 2.52–2.55 (m, 1H,
Cpr-CH), 2.90 (s, 3H, NCH3), 3.51 (q, 2H, J = 7.16 Hz, CH2), 3.71–
3.75 (m, 1H, Cpr-CH), 4.56 (br s, 1H, NH), 5.34 (br s, 1H, NH), 5.40
(s, 2H, PhCH2O), 7.06–7.08 (m, 1H), 7.30–7.43 (m, 6H,), 7.55 (d, 2H,
J = 7.40 Hz), 8.04 (d, 1H, J = 8.44 Hz). 13C-NMR (CDCl3, 100 Hz), d
12.14, 19.05, 25.72, 33.87, 37.49, 59.92, 70.01, 110.32, 118.94,
121.69, 125.40, 126.06, 126.72, 127.35, 127.48, 135.04, 136.26,
139.00, 153.15, 154.18, 158.63, 171.06. MS m ⁄ z 420.2 (M+ + 1).
Anal. Calcd. For C24H25N3O4: C, 68.72; H, 6.01; N, 10.02. Found: C,
68.81; H, 6.07; N, 10.07.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-
cyclohexylureido)cyclopropanecarboxylate (7f)
1
Mp: 163–165 ꢀC, yield = 80%. H-NMR (CDCl3, 400 MHz), d 0.41 (t,
3H, J = 7.12 Hz, CH3), 1.22–1.88 (m, 10H), 2.28–2.31 (m, 1H, Cpr-
CH), 2.51–2.54 (m, 1H, Cpr-CH), 3.53 (q, 2H, J = 7.12 Hz, CH2),
3.71–3.76 (m, 1H, Cpr-CH), 3.73–3.82 (m, 1H), 4.89 (br s, 1H, NH),
5.22 (br s, 1H, NH), 5.29 (s, 2H, PhCH2O), 7.07–7.09 (m, 1H), 7.29–
7.44 (m, 6H), 7.92(d, 1H, J = 7.48 Hz), 8.38(d, 1H, J = 8.44 Hz). 13C-
NMR (CDCl3, 100 Hz), d 12.12, 19.15, 23.66, 24.64, 31.69, 31.91,
33.93, 37.22, 47.54, 52.44, 59.82, 69.99, 110.19, 118.93, 121.67,
125.34, 126.04, 126.68, 127.27, 127.45, 134.95, 136.19, 138.92,
153.11, 154.27, 159.74, 169.98. MS m ⁄ z 488.6 (M+ + 1). Anal.
Calcd. For C29H33N3O4: C, 71.44; H, 6.82; N, 8.62. Found: C, 71.51;
H, 6.79; N, 8.55.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-
butylureido)cyclopropanecarboxylate (7c)
1
Mp: 143–145 ꢀC, yield = 78%. H-NMR (CDCl3, 400 MHz), d 0.51 (t,
3H, J = 7.16 Hz, CH3), 0.95 (t, 3H, J = 7.32 Hz, CH3), 1.25–1.43 (m,
2H, CH2), 1.53–1.58 (m, 2H, CH2), 2.28–2.31 (m, 1H, Cpr-CH), 2.51–
2.54 (m, 1H, Cpr-CH), 3.29–3.40 (m, 2H, CH2), 3.53 (q, 2H,
J = 7.16 Hz, CH2), 3.71–3.76 (m, 1H, Cpr-CH), 4.62 (br s, 1H, NH),
4.99 (br s, 1H, NH), 5.39 (s, 2H, PhCH2O), 7.07–7.09 (m, 1H), 7.29–
7.44 (m, 6H), 7.56 (d, 1H, J = 7.48 Hz), 8.04 (d, 1H, J = 8.44 Hz).
13C-NMR (CDCl3, 100 Hz), d 12.48, 13.16, 19.55, 29.03, 30.79,
34.26, 37.68, 39.13, 60.23, 70.33, 110.52, 119.27, 122.05, 125.72,
126.42, 127.07, 127.65, 127.83, 135.36, 136.54, 139.27, 153.46,
154.57, 157.18, 170.38. MS m ⁄ z 462.3 (M+ + 1). Anal. Calcd. For
C27H31N3O4: C, 70.26; H, 6.77; N, 9.10. Found: C, 70.33; H, 6.57; N,
9.17.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-
phenylureido)cyclopropanecarboxylate (7g)
1
Mp: 117–120 ꢀC, yield = 85%. H-NMR (CDCl3, 400 MHz), d 0.40 (t,
3H, J = 7.16 Hz, CH3), 2.31–2.34 (m, 1H, Cpr-CH), 2.51–2.53 (m, 1H,
Cpr-CH), 3.47 (q, 2H, J = 7.16 Hz, CH2), 3.62–3.68 (m, 1H, Cpr-CH),
5.27 (s, 2H, PhCH2O), 6.01(br s, 1H, NH), 6.62 (br s, 1H, NH), 6.96–
7.01 (m, 2H), 7.19–7.29 (m, 7H), 7.33 (d, 1H, J = 8.44 Hz), 7.46 (d,
2H, J = 7.44 Hz), 7.53 (d, 2H, J = 8.00 Hz), 7.93 (d, 1H,
J = 8.44 Hz). 13C-NMR (CDCl3, 100 Hz), d 12.06, 19.48, 34.15,
38.51, 60.19, 69.90, 110.13, 118.88, 119.04, 121.60, 123.05, 125.51,
126.05, 126.71, 127.30, 127.45, 127.85, 135.12, 136.08, 137.16,
138.87, 153.06, 153.75, 158.06, 171.23. MS m ⁄ z 482.6 (M+ + 1).
Anal. Calcd. For C29H27N3O4: C, 72.33; H, 5.65; N, 8.73. Found: C,
72.45; H, 5.54; N, 8.66.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-
isopropylureido)cyclopropanecarboxylate (7d)
Mp: 123–125 ꢀC, yield = 80%. 1H-NMR (CDCl3, 400 MHz), d 0.52
(t, 3H, J = 7.12 Hz, CH3), 1.22 (dd, 6H, J1 = 16.04 Hz,
J2 = 6.60 Hz, 2 · CH3), 2.26–2.29 (m, 1H, Cpr-CH), 2.50–2.52 (m,
1H, Cpr-CH), 3.46–3.50 (m, 1H, Cpr-CH), 3.72 (q, 2H, J = 7.12 Hz,
CH2), 4.13 (m, 1H, Cpr-CH), 5.52 (br s, 1H, NH), 5.38 (s, 2H,
Chem Biol Drug Des 2012; 79: 771–779
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He et al.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-
benzylureido)cyclopropanecarboxylate (7h)
Mp: 101–103 ꢀC, yield = 88%. H-NMR (CDCl3, 400 MHz), d 0.33 (t,
125.82, 126.72, 126.98, 130.43, 134.87, 136.32, 137.92, 143.44,
152.34, 152.98, 156.72, 172.33. MS m ⁄ z 527.6 (M+ + 1). Anal.
Calcd. For C29H26N4O6: C, 66.15; H, 4.98; N, 10.64. Found: C, 66.22;
H, 4.87; N, 10.78.
1
3H, J = 7.16 Hz, CH3), 2.21–2.25 (m, 1H, Cpr-CH), 2.43–2.46 (m, 1H,
Cpr-CH), 3.39 (q, 2H, J = 7.16 Hz, CH2), 3.52–3.60 (m, 1H, Cpr-CH),
4.42 (s, 2H, PhCH2), 5.23 (s, 2H, PhCH2O), 6.44 (br s, 1H, NH), 6.91–
6.95 (m, 1H), 7.06–7.24 (m, 11H), 7.41 (d, 2H, J = 7.24 Hz), 7.87 (d,
1H, J = 8.48 Hz), 8.41 (br s, 1H, NH). 13C-NMR (CDCl3, 100 Hz), d
13.14, 20.38, 34.91, 38.68, 44.15, 60.98, 70.93, 111.16, 119.96,
122.72, 126.50, 127.06, 127.34, 127.77, 128.35, 128.45, 128.52,
128.69, 136.11, 137.19, 138.35, 139.94, 154.12, 155.09, 158.12,
170.90. MS m ⁄ z 496.6 (M+ + 1). Anal. Calcd. For C30H29N3O4: C,
72.71; H, 5.90; N, 8.48. Found: C, 72.85; H, 5.97; N, 8.53.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-(4-
fluorophenyl)ureido)cyclopropanecarboxylate
(7l)
1
Mp: 159–160 ꢀC, yield = 82%. H-NMR (CDCl3, 400 MHz), d 0.53 (t,
3H, J = 7.12 Hz, CH3), 2.39–2.42 (m, 1H, Cpr-CH), 2.58–2.61 (m, 1H,
Cpr-CH), 3.56 (q, 2H, J = 7.12 Hz, CH2), 3.74–3.80 (m, 1H, Cpr-CH), 5.23
(s, 2H, PhCH2O), 7.03–7.11 (m, 3H), 6.55 (br s, 1H, NH), 7.30–7.59 (m,
10H), 8.08 (d, 1H, J = 8.48 Hz), 8.27 (br s, 1H, NH). 13C-NMR (CDCl3,
100 Hz), d 11.98, 18.65, 31.88, 37.44, 59.34, 70.68, 108.48, 113.66,
117.88, 119.33, 122.34, 124.76, 125.43, 125.88, 126.74, 126.88,
131.56, 133.46, 136.77, 137.99, 144.46, 153.41, 156.66, 161.54,
172.56. MS m ⁄ z 500.6 (M+ + 1). Anal. Calcd. For C29H26FN3O4: C,
69.73; H, 5.25; N, 8.41. Found: C, 69.93; H, 5.14; N, 8.55.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-p-
tolylureido)cyclopropanecarboxylate (7i)
1
Mp: 159–160 ꢀC, yield = 80%. H-NMR (CDCl3, 400 MHz), d 0.52 (t,
3H, J = 7.16 Hz, CH3), 2.32 (s, 3H, CH3), 2.40–2.44 (m, 1H, Cpr-CH),
2.61–2.64 (m, 1H, Cpr-CH), 3.57 (q, 2H, J = 7.16 Hz, CH2), 3.75–3.79
(m, 1H, Cpr-CH), 5.39 (s, 2H, PhCH2O), 7.07–7.14 (m, 2H), 6.15 (s,
1H, NH), 7.30–7.39 (m, 6H), 7.45 (d, 1H, J = 8.44 Hz), 7.50 (d, 2H,
J = 8.16 Hz), 7.56 (d, 2H, J = 7.56 Hz), 8.05 (d, 1H, J = 8.48 Hz),
8.27 (s, 1H, NH). 13C-NMR (CDCl3, 100 Hz), d 11.48, 20.21, 20.93,
35.40, 39.23, 61.25, 70.98, 111.17, 115.25, 119.98, 126.60, 127.23,
127.42, 127.84, 128.39, 128.56, 129.44, 133.60, 135.82, 136.22,
137.14, 139.91, 154.12, 154.93, 155.97, 171.22. MS m ⁄ z 496.6
(M+ + 1). Anal. Calcd. For C30H29N3O4: C, 72.71; H, 5.90; N, 8.48.
Found: C, 72.62; H, 6.04; N, 8.55.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-(4-
(trifluoromethyl)phenyl)
ureido)cyclopropanecarboxylate (7m)
1
Mp: 159–160 ꢀC, yield = 78%. H-NMR (CDCl3, 400 MHz), d 0.54 (t,
3H, J = 7.12 Hz, CH3), 1.88–1.92 (m, 1H, Cpr-CH), 2.75–2.78 (m, 1H,
Cpr-CH), 3.38 (q, 2H, J = 7.12 Hz, CH2), 3.75–3.79 (m, 1H, Cpr-CH),
5.20 (s, 2H, PhCH2O), 6.43 (br s, 1H, NH), 7.08–7.12 (m, 2H), 7.11–
7.55 (m, 11H), 8.05 (d, 1H, J = 8.56 Hz), 8.62 (br s, 1H, NH). 13C-
NMR (CDCl3, 100 Hz), d 13.22, 20.35, 20.96, 35.38, 39.43, 61.62,
71.04, 111.74, 115.89, 119.88, 124.34, 126.76, 127.73, 127.79,
127.84, 128.36, 128.66, 129.34, 133.50, 135.87, 136.80, 137.34,
139.98, 154.22, 154.98, 165.45, 171.71. MS m ⁄ z 550.5 (M+ + 1).
Anal. Calcd. For C30H26F3N3O4: C, 65.57; H, 4.77; N, 7.65. Found: C,
65.42; H, 4.67; N, 7.43.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-(4-
methoxyphenyl)
ureido)cyclopropanecarboxylate (7j)
1
Mp 124–126 ꢀC, yield = 78.7%. H-NMR (CDCl3, 400 MHz), d 0.45
(t, 3H, J = 7.16 Hz, CH3), 2.33–2.37 (m, 1H, Cpr-CH), 2.54–2.56 (m,
1H, Cpr-CH), 3.50 (q, 2H, J = 7.16 Hz, CH2), 3.68–3.73 (m, 1H, Cpr-
CH), 3.75 (s, 3H, OCH3), 5.33 (s, 2H, PhCH2O), 6.72 (br s, 1H, NH),
6.80 (d, 2H, J = 8.96 Hz), 7.00–7.50 (m, 11H), 7.99 (d, 1H,
J = 8.44 Hz), 8.66 (br s, 1H, NH). 13C-NMR (CDCl3, 100 Hz), d 11.00,
18.42, 32.91, 37.40, 53.36, 59.09, 68.92, 109.19, 111.94, 117.83,
119.64, 120.60, 124.40, 124.94, 125.62, 126.26, 126.39, 129.33,
134.01, 135.10, 137.89, 152.07, 152.81, 154.12, 159.74, 171.32. MS
m ⁄ z 482.6 (M+ + 1). Anal. Calcd. For C30H29N3O4: C, 72.71; H, 5.90;
N, 8.48. Found: C, 72.62; H, 6.04; N, 8.53.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-(4-
chlorophenyl)ureido)cyclopropanecarboxylate
(7n)
1
Mp: 118–120 ꢀC, yield = 80%. H-NMR (CDCl3, 400 MHz), d 0.53 (t,
3H, J = 7.12 Hz, CH3), 2.39–2.42 (m, 1H, Cpr-CH), 2.58–2.61 (m, 1H,
Cpr-CH), 3.58 (q, 2H, J = 7.12 Hz, CH2), 3.76–3.80 (m, 1H, Cpr-CH),
5.39 (s, 2H, PhCH2O), 6.71 (br s, 1H, NH), 7.09–7.11 (m, 2H), 7.26–
7.58 (m, 11H), 8.08 (d, 1H, J = 8.44 Hz), 8.55 (br s, 1H, NH). 13C-
NMR (CDCl3, 100 Hz), d 13.11, 20.64, 20.93, 35.11, 39.69, 61.33,
70.97, 111.11, 116.21, 119.92, 121.31, 122.64, 126.63, 127.18,
127.83, 128.39, 128.94, 136.24, 136.83, 137.08, 139.89, 144.96,
154.10, 154.73, 156.71, 171.30. MS m ⁄ z 516.5 (M+ + 1). Anal.
Calcd. For C29H26ClN3O4: C, 67.50; H, 5.08; N, 8.41. Found: C, 67.62;
H, 5.16; N, 8.55.
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-(4-
nitrophenyl)ureido)cyclopropanecarboxylate
(7k)
1
Mp: 114–116 ꢀC, yield = 85%. H-NMR (CDCl3, 400 MHz), d 0.62 (t,
3H, J = 7.12 Hz, CH3), 1.90–1.94 (m, 1H, CH), 2.73–2.76 (m, 1H,
CH), 3.29–3.33 (q, 2H, J = 7.16 Hz, CH2), 3.75–3.79 (m, 1H, CH),
5.23 (s, 2H, PhCH2O), 6.33 (br s, 1H, NH), 7.07–7.14 (m, 2H), 7.30–
7.39 (m, 6H), 7.45 (d, 1H, J = 8.44 Hz), 7.50 (d, 2H, J = 8.16 Hz),
7.56(d, 2H, J = 7.56 Hz), 8.05 (d, 1H, J = 8.48 Hz), 8.64 (br s, 1H,
NH). 13C-NMR (CDCl3, 100 Hz), d12.10, 19.35, 31.83, 37.66, 60.04,
69.88, 109.45, 112.43, 117.76, 119.43, 121.64, 124.88, 124.96,
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-(4-
bromophenyl)ureido)cyclopropanecarboxylate
(7o)
Mp: 105–107 ꢀC, yield = 88%. H-NMR (CDCl3, 400 MHz), d 0.42 (t,
3H, J = 7.16 Hz, CH3), 2.20–2.46 (m, 1H, Cpr-CH), 2.31–2.49 (m, 1H,
1
774
Chem Biol Drug Des 2012; 79: 771–779

Synthesis and Anticonvulsant Activity of Urea Derivatives
Cpr-CH), 3.46 (q, 2H, J = 7.16 Hz, CH2), 3.63–3.69 (m, 1H, Cpr-CH),
Pentylenetetrazole (PTZ)-induced seizure test
(23)
5.26 (s, 2H, PhCH2O), 6.26 (br s, 1H, NH), 6.39–6.41 (m, 2H), 6.89–
7.46 (m, 11H), 7.96 (d, 1H, J = 8.46 Hz), 8.74(br s, 1H, NH). 13C-
NMR (CDCl3, 100 Hz), d 13.70, 18.12, 34.21, 38.39, 60.31, 69.88,
109.94, 115.63, 118.85, 120.60, 121.57, 125.62, 126.77, 127.79,
129.90, 130.77, 135.25, 135.93, 136.30, 138.72, 144.48, 152.98,
153.68, 156.66, 170.10. MS m ⁄ z 561.4 (M+ + 1). Anal. Calcd. For
C30H29N3O4: C, 62.15; H, 4.68; N, 7.50. Found: C, 62.23; H, 4.82; N,
7.38.
Pentylenetetrazole was dissolved in sufficient 0.9% saline to allow
subcutaneous injections to mice or rat. Standard drug in this model
was ethosuximide. After 0.5 and 4.0 h of drug administration,
the failure to observe even a threshold seizure (a single episode
of clonic spasms of at least 5 seconds duration) is defined as
protection.
Neurotoxicity screening (24)
Ethyl 2-(8-(benzyloxy)quinolin-2-yl)-1-(3-(3,5-
dichlorophenyl)ureido)cyclopropanecarboxylate
(7p)
The mouse was placed on a 1-in.-diameter knurled plastic rod rotat-
ing at 6 rpm. Trained animals were given an ip injection of the test
compounds in doses of 30, 100, and 300 mg ⁄ kg. Neurotoxicity was
indicated by the inability of the animal to maintain equilibrium on
the rod for at least 1 min in each of the four trials.
1
Mp: 131–133 ꢀC, yield = 82%. H-NMR (CDCl3, 400 MHz), d 0.44 (t,
3H, J = 7.12 Hz, CH3), 2.18–2.34 (m, 1H, Cpr-CH), 2.33–2.51 (m, 1H,
Cpr-CH), 3.48 (q, 2H, J = 7.12 Hz, CH2), 3.72–3.75 (m, 1H, Cpr-CH),
5.23 (s, 2H, PhCH2O), 6.05 (br s, 1H, NH), 6.43–6.51 (m, 2H), 6.84–
7.55 (m, 10H), 8.05 (d, 1H, J = 8.56 Hz), 8.43 (br s, 1H, NH). 13C-
NMR (CDCl3, 100 Hz), d 13.88, 20.56, 21.03, 35.87, 39.41, 61.44,
70.98, 110.91, 115.46, 120.28, 126.74, 127.53, 127.76, 127.82,
128.43, 128.76, 129.42, 133.61, 134.84, 136.76, 137.24, 140.94,
154.33, 154.87, 166.91, 171.62. MS m ⁄ z 551.4 (M+ + 1). Anal.
Calcd. For C29H25Cl2N3O4: C, 63.28; H, 4.58; N, 7.63. Found: C,
63.36; H, 4.74; N, 7.47.
Quantification studies (25)
Anticonvulsant activity was expressed in terms of the median effec-
tive dose (ED50), that is, the dose of drug required to produce the
biological responses in 50% of animals, and neurotoxicity was
expressed as the median toxic dose (TD50). For the determination of
the ED50 and TD50, groups of 10 mice were given a range of ip
doses of the test drug until at least three points were established
in the range of 10–90% seizure protection or minimal observed
neurotoxicity. From the plot of these data, the respective ED50 and
TD50 values, 95% confidence intervals, slope of the regression line,
and standard error of the slope were calculated by means of a
computer program written at NINDS, NIH.
Pharmacology
Male Kunming mice (20 € 2.0 g) were used as experimental ani-
mals in this study. Animals of the same age and weight have been
selected in order to minimize biological. The present study was per-
formed in accordance with the guidelines of the National Institutes
of Health Guide for the Care and Use of Laboratory Animals (NIH
Pub. No. 85-23, revised 1996) and was approved by the Animal
Care Committee of Wuhan University. All the animals were pur-
chased from Wuhan University Laboratory Animal Center (Wuhan
China). The tested compounds were injected intraperitoneally to
mice as a suspension in 0.5% methylcellulose at a dose of 30, 100,
and 300 mg ⁄ kg to one to four mice. The anticonvulsant activity of
the tested compounds was evaluated by two models namely maxi-
mal electroshock seizure (MES) and subcutaneous pentylenetetraz-
ole (scPTZ) models. Phenytoin and ethosuximide were used as the
standard drugs for the comparison. The neurological toxicity was
determined in the rotorod test. Procedures employed for the evalua-
tion of anticonvulsant activity and neurotoxicity were described
elsewhere (20,21).
Results and Discussion
The synthesis of target compounds 7a–p was accomplished as pre-
sented in Scheme 1. We have succeeded in a simple and conve-
nient preparation of compound
1 by the reaction of 2-
methylquinoline-8-ol with benzyl bromide in anhydrous ethanol in
the presence of NaOC2H5 in 90% yield (26). Compound 1 was
reacted with SeO2 in anhydrous dioxane to afford the compound 2
in high yield (98%) (27). Then, compound 3 was prepared by con-
densation of diethyl malonate with compound 2. Compound 3
underwent cyclopropane formation with trimethylsulphoxoniumylide
to afford compound 4 (28). Then, monoester compound 5 was
obtained after monosaponification in a 1 N NaOH ⁄ ethanol (1.1
equiv) solution at room temperature for 12 h (29). This was then
converted to acyl azide by using ethyl chloroformate in the presence
of triethylamine (Et3N) followed by reaction with sodium azide in a
one-pot synthesis. a-Carboethoxyisocyanate 6 was successfully gen-
erated by a Curtius reaction in situ on heating the acyl azide in
anhydrous toluene solution at 75 ꢀC. Isocyanate 6 was allowed to
react directly with various amines without isolation. The desired a-
carboethoxyureas7a–p was readily obtained in good yields
(yield ‡ 90%).
MES-maximal electroshock seizure pattern test
(22)
In experiments with mice, a 60-Hz current of 50-mA intensity was
applied through corneal electrodes for a 0.25 seconds duration;
with rats, seizure activity was induced by delivery of a 150-mA cur-
rent (0.2 seconds) to the cornea. Both procedures caused immediate
hindlimb tonic extension. After 0.5 and 4.0 h of drug administration,
electroshocks were via corneal electrodes. Absence of tonic exten-
sion suggests that the tested compound was considered as positive
criteria.
The anticonvulsant activity and neurotoxicity of the synthesized
compounds were evaluated following the standard procedures pro-
posed by the NIH anticonvulsant drug development program, via the
Chem Biol Drug Des 2012; 79: 771–779
775

He et al.
C2H5ONa
PhCH2Br
CH2(COOC2H5)2
SeO2
N
N
OCH2Ph
1
N
OCH2Ph
2
CHO
OH
COOC2H5
COOC2H5
COOH
COOC2H5
COOC2H5
NaH, TMSOI
DMSO
1N, NaOH
N
N
N
COOC2H5
OCH2Ph
OCH2Ph
OCH2Ph
5
3
4
O
1) C2H5OCOCl
Et3N, NaN3
NCO
NHCNHR
RNH2
r.t.
N
N
COOC2H5
COOC2H5
2) toluene, 75°C
OCH2Ph
OCH2Ph
7a-p
6
R
R
a: R=H
i: R=4-CH3C6H4
j: R=4-OCH3C6H4
k: R=4-NO2C6H4
l: R=4-FC6H4
m: R=4-CF3C6H4
n: R=4-ClC6H4
b: R=CH3
c: R=C4H9
d: R=(CH3)2CH
e: R=CH3CH2(CH2OH)CH
f: R=C6H11
g: R=C6H5
h: R=CH2C6H5
o: R=4-BrC6H4
p: R=3,5-diClC6H3
Scheme 1: General method for the synthesis of compounds 7a–p.
anticonvulsant screening project (30). The initial evaluation (Phase I)
included the MES, the scPTZ, and neurotoxicity.
In the neurotoxicity screen, compounds that did not show any neu-
rotoxicity at the highest dose (300 mg ⁄ kg) included 7c, 7e, 7h,
and 7k. These compounds did not cause any motor impairment at
the three doses at the two time periods. Compounds 7a and 7g
were less neurotoxic than phenytoin and exhibited motor impair-
ment at the dose of 300 mg ⁄ kg at 0.5 h and also 4.0 h (7g). Com-
pounds 7d, 7j, 7n, and 7o revealed neurotoxicity at a dose of
100 mg ⁄ kg at 0.5 h.
The MES test is associated with the electrical induction of the
seizure, whereas PTZ test involves a chemical induction to gener-
ate the convulsion. Neurotoxicity is primarily determined in the
minimal motor impairment-rotorod screen. The calculated LogP(-
Clogp) values were calculated using the software in ACDLabs 8.0
version.
Compounds 7a, 7e, and 7m were selected for quantification of
the pharmacological parameters (ED50 and TD50). Results of the
quantitative test for the compounds, along with the data on the
standard drugs (phenytoin, carbamazepine, phenobarbital, and val-
proate), are reported in Table 2. In the mice ip MES screen, com-
pounds 7a, 7e, and 7m showed a higher protective index (PI)
than all the standard drugs. In the mice ip scPTZ screen, compound
7e gave an ED50 of 89.3 mg ⁄ kg and a TD50 of 434 mg ⁄ kg, result-
ing in a high protection index (PI), that is, TD50 ⁄ ED50, of 4.9 when
compared to phenobarbital and valproate.
The compounds 7a–p were administrated intraperitoneally (ip) into
the mice using dose of 30, 100, and 300 mg ⁄ kg, and the observa-
tions were taken at two different time intervals (0.5 and 4.0 h).
Neurotoxicity was measured by the rotorod test. The results are
shown in Table 1.
In the MES test, compounds 7a, 7e, and 7m were active against
MES test at a dose of 30 mg ⁄ kg at 0.5 h. The most active com-
pound was 7e, which presented 50% of protection at a dose of
30 mg ⁄ kg at 0.5 h. Interestingly, compound 7e continued to protect
from the seizures at a dose of 30 mg ⁄ kg at 4.0 h also. It indicates
that 7e have rapid onset and long duration of anticonvulsant at
lower dose. Compounds 7a and 7m were active at 4.0 h but at
the higher dose of 100 mg ⁄ kg.
In the present studies, we have synthesized a library of compounds
with 2-quionlincyclopropaneurea as a core fragment, and at the
position-N' of urea, we have introduced different substituents. In
the preliminary anticonvulsant screen, all of the alkyl- and aryl-
substituted 2-quionlincyclopropaneurea showed better protection
against ip MES test but less response toward scPTZ test.
Compounds that were active at a dose of 100 mg ⁄ kg only at 0.5 h
in MES screen included 7c and 7l, indicating that they have rapid
onset and short duration of anticonvulsant activity. Compound 7i
did not show any activity at two time periods in MES screen.
All the compounds with alkyl substituents at N¢ (7a, 7b, 7c, 7d,
7e) were active against MES screen at 0.5 h, which showed more
rapid onset than aryl-substituted derivatives. On the other hand, the
most active compound was 7e in which introduction of hydrophilic
group at branch of alkyl chain resulted in increased anticonvulsant
activity; therefore, the presence of the hydrophilic group seems to
be important, however, not crucial for anticonvulsant activity. When
the alkyl groups were replaced by a phenyl ring, substitution of
electron-donating groups like methoxy and methyl at the para posi-
In the scPTZ screen, compounds that showed protection at 0.5 h
were 7a, 7d, 7e, 7f, 7h, and 7k. Among these compounds, 7d
and 7e showed anti-scPTZ activity at the dose of 100 mg ⁄ kg at
time periods 0.5 h. Compounds 7b, 7c, and 7m were active only
at 4.0 h at a dose of 300 mg ⁄ kg indicative of the long duration of
action of these compounds.
776
Chem Biol Drug Des 2012; 79: 771–779

Synthesis and Anticonvulsant Activity of Urea Derivatives
Table 1: Anticonvulsant activity and neurotoxicity of compounds 7a–7o administered intraperitoneally to mice
Intraperitoneal injection in mice (h)a
MESc
scPTZd
Neurotoxicitye
0.5
Compounds
0.5
4.0
0.5
4.0
4.0
Clog Pb
7a
7b
30
300
100
300
30
300
–
–
–
–
–
100
–
–
100
30
300
300
300
–
300
300
–
100
–
300
300
30
300
–
–
100
100
300
–
300
–
–
300
–
–
–
–
300
–
–
100
–
–
300
–
–
100
–
–
–
300
–
–
–
300
300
–
300
–
2.18 € 0.40
2.39 € 0.44
3.99 € 0.44
3.27 € 0.45
2.64 € 0.48
4.45 € 0.45
4.52 € 0.43
4.17 € 0.47
4.98 € 0.43
4.16 € 0.62
4.97 € 0.46
4.96 € 0.51
5.53 € 0.49
5.47 € 0.54
5.68 € 0.51
6.65 € 0.52
2.52 € 0.38
0.38 € 0.46
300
300
–
–
–
–
–
–
–
7c
7d
7e
7f
7g
7h
7i
7j
7k
–
–
300
–
7l
7m
100
30
300
–
300
300
300
300
300
100
–
–
7n
7o
100
100
–
100
–
–
–
–
100
–
–
–
7p
Phenytoinf
Ethosuximideg
30
–
–
300
MES, maximal electroshock seizure; scPTZ, subcutaneous pentylenetetrazole.
a30, 100, and 300 mg ⁄ kg of doses were administered ip. The figures in the table indicate the minimal dose whereby bioactivity was demonstrated in half or
more of the mice. The animals were examined at 0.5 and 4.0 h after injection was administered. A dash indicates an absence of activity at maximum dose
administered (300 mg ⁄ kg).
bClog P was calculated using software ACD Labs 8.0 version.
cMaximal electroshock test.
dSubcutaneous pentylenetetrazole test.
eNeurotoxicity screening (rotorod test).
fData from Reference (38).
gData from Reference (39).
Table 2: Phase-II quantitative anticonvulsant evaluation in mice (test drug administered i.p.)
PIc
a
ED50
b
Compound
MES
scPTZ
215 (172)
89.3 (66.4)
203.3 (168.3)
>300
>100
13.2 (5.8–15.9)
149 (123–177)
TD50
MES
scPTZ
7a
7e
24.3 (19.8)
14.3 (9.9)
28.4 (22.6)
9.5 (8.1–10.4)
8.8 (5.5–14.1)
21.8 (21.8–25.5)
272 (247–338)
365 (353
434 (389
270 (202
65.5 (52.5–72.9)
71.6 (45.9–135)
69 (62.8–72.9)
426 (369–450)
15.0
30.3
9.5
6.9
8.1
1.7
4.9
1.3
<0.22
<0.22
5.2
7m
Phenytoind
Carbamazepined
Phenobarbitald
Valproated
3.2
1.6
2.9
MES, maximal electroshock seizure; scPTZ, subcutaneous pentylenetetrazole.
Number of animals used: 10; solvent used: polyethylene glycol (0.1 mL, i.p.).
aDose in milligrams per kilogram body mass.
bMinimal toxicity which was determined by rotorod test 30 min after the test drug was administered.
cProtection index (TD50 ⁄ ED50).
dDate from reference (40).
Date in parentheses are the 95% confidence limits.
tion of phenyl ring resulted in decreased anticonvulsant activity. For
example, the 4-methyl (7i) and 4-methoxy (7j) substituent deriva-
tives were less potent than 4-nitro (7k) and 4-trifuloro (7m) deriva-
tives. Compounds 7i, 7n, and 7o did not show apparent activity in
MES and scPTZ screen, and the ClogP of these compounds were
far from 2.0, which is considered to be the optimum lipophilicity for
the congeners that act on the central nervous system (CNS) (31).
Clog P values may be indicated the importance of lipophilicity as
Chem Biol Drug Des 2012; 79: 771–779
777

He et al.
well as electronic properties of the substituents on the activity of
these compounds. It was previously shown that there is a correla-
tion between anticonvulsant activity and Clog P values, where an
increase in ClogP is correlated with increased anticonvulsant prop-
erties (32,33). The antiepileptic candidate drug must work at CNS
level, the lipophilicity seriously affects the capability of the com-
pound to be able to cross the blood–brain barrier, and relatively
favorable anticonvulsant activity was indicated in one study for
compounds displaying Clog P values between 1.84 and 2.64 (34),
which is in agreement with the optimal physical–chemical parame-
ters for targeting CNS drugs (35). The sulfonylurea and thiourea
functions of 1-(2-(8-(benzyloxy)quinolin-2-yl)-1-butyrylcyclopropyl)-3-
substituted urea derivatives could be regarded chemically as bio-
isosteres of the cyclic acylurea moiety of phenytoin. So, the inhibi-
tion of electrically induced seizures that is characteristic for
sulfonylureas and thioureas may indicate the influence of com-
pounds on Na+ 2 HCI) K+ cotransporter as the most plausible
mechanism of anticonvulsant action (36,37). The anticonvulsant
properties of 1-(2-(8-(benzyloxy)quinolin-2-yl)-1-butyrylcyclopropyl)-3-
substituted urea derivatives could perhaps be mediated by a similar
pathway. Further experiments in binding and electrophysiology are
clearly necessary to elucidate the mechanism of action of these
novel anticonvulsants.
3. Perucca E., French J., Bialer M. (2007) Development of new an-
tiepileptic drugs: challenges, incentives, and recent advances.
Lancet Neurol;6:793–804.
4. Chen Y.L., Fang K.C., Shen J.Y., Hsu S.L., Tzeng C.C. (2001) Syn-
thesis and antibacterial evaluation of certain quinolone deriva-
tives. J Med Chem;44:2374–2386.
5. Liu G., Xu J., He C., Chen G., Xu Q., Xu H., Li J. (2009) Synthe-
sis and evaluation of a novel series of quinoline derivatives with
immunosuppressive activity. Bioorg Med Chem;17:5433–5441.
6. Shinkai H., Ito T., Ida T., Kitao Y., Yamadu H., Uchida I. (2000) 4-
Aminoquinolines: novel nociceptinantagonists with analgesic
activity. J Med Chem;43:4667–4672.
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9. Joseph B., Darro F., Behard A., Lesur B., Collignon F., Decaestec-
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Conclusion
10. Billah M.H., Cooper N., Minnicozzi M., Warneck J., Wang P.,
Hey J.A., Kreutner W. et al. (2002) Pharmacology of N-(3,5-Di-
chloro-1-oxido-4-pyridinyl)-8-methoxy-2- (trifluoromethyl)-5-quino-
In summary, the present studies revealed that number of 1-(2-(8-
(benzyloxy)quinolin-2-yl)-1-butyrylcyclopropyl)-3-substituted
urea
line carboxamide (SCH 351591), a novel, orally active
derivatives was effective in the MES and ⁄ or scPTZ screens. In
the neurotoxicity studies, some of the active compounds were
devoid of toxicity. The most active was ethyl 2-(8-(benzyloxy)quino-
lin-2-yl)-1-(3-ethyl-3-(hydroxymethyl)ureido)cyclopropanecarboxylate
(7e) that showed ED50 value of 14.3 mg ⁄ kg and a protective
index (TD50 ⁄ ED50) of 30.3 in the MES test in mice. This compound
showed good Clog P value (2.64 € 0.48) for the congeners that
act on the CNS and greater ED50 and lower TD50 to standard
drugs.
phosphodiesterase 4 Inhibitor. J Pharmacol Exp Ther;302:127–
137.
11. Neha G., Trilok C., Ashok K. (2010) Synthesis and anticonvulsant
activity of substituted quinoline derivatives. Int J Pharm Pharm
Sci;2(Suppl.2):88–92.
12. Guo L., Wei C., Jia J., Zhao L., Quan Z. (2009) Design and syn-
thesis of 5-alkoxy-[1,2,4]triazolo[4,3-a] quinoline derivatives with
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Acknowledgments
14. Jiang L., Liu F., Zhang D.K., Wang H.B. (2010) Synthesis and
antifungal activity of 1-(substituted phenyl)-3-(5-halobenzimidazol-
2-yl)acyl urea. J Pestic Sci;35:33–35.
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This investigation was made possible through the financial support
of the Important National Science & Technology Specific Projects,
China (Grant No. 2009ZX09301-14-1) and Key Project of Science &
Technology of HuBei Province, China (Grant NO. 2008CDA057).
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