Design, synthesis and antidepressant activity evaluation 2′-hydroxy-4′,6′-diisoprenyloxychalcone derivatives

Article abstract of DOI:10.1007/s00044-013-0517-4

In this study, 14 2′-hydroxy-4′,6′-diisoprenyloxychalcone compounds were synthesized and their antidepressant activities were evaluated using the forced swimming test. The pharmacological results showed that six compounds significantly reduced immobility times during the forced swimming test at a dose of 10 mg/kg, indicative of antidepressant activity. Among these, three compounds (4d, 4e, and 4g) exhibited better antidepressant activity, with reduced immobility time by 38.3, 34.0, and 27.4 %, respectively. For explanation of the putative mechanism of action, compounds 4e, 4g were tested in chemical induced models.

Full text of DOI:10.1007/s00044-013-0517-4

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-013-0517-4
ORIGINAL RESEARCH
Design, synthesis and antidepressant activity evaluation
20-hydroxy-40,60-diisoprenyloxychalcone derivatives
•
•
•
•
•
Li-Ping Guan Dong-Hai Zhao Yue Chang Yu Sun Xiao-Li Ding
Jing-Fei Jiang
Received: 19 December 2012 / Accepted: 29 January 2013
Ó Springer Science+Business Media New York 2013
Abstract In this study, 14 20-hydroxy-40,60-diisoprenyl-
oxychalcone compounds were synthesized and their anti-
depressant activities were evaluated using the forced
swimming test. The pharmacological results showed that
six compounds significantly reduced immobility times
during the forced swimming test at a dose of 10 mg/kg,
indicative of antidepressant activity. Among these, three
compounds (4d, 4e, and 4g) exhibited better antidepressant
activity, with reduced immobility time by 38.3, 34.0, and
27.4 %, respectively. For explanation of the putative
mechanism of action, compounds 4e, 4g were tested in
chemical induced models.
Introduction
Depression is one of the most prevalent psychopathologies.
Symptoms of depression include lowered mood and
reduced interest and pleasure. It is predicted by the World
Health Organization to become the second leading cause of
disease-related disability by the year 2020 (Meyer, 2004;
Lopez and Murray, 1998). Therefore, there is an unmet
need for new antidepressant drugs.
Chalcones are the biogenetic precursors of all known
flavonoids and are abundant in edible plants (Go et al.,
2005). They comprise open-chain flavonoids in which
the two aromatic rings are joined by a three-carbon a,
b-unsaturated carbonyl system. They have a broad spectrum
of biological activities, such as anticancer, anti-inflamma-
tory, antimalarial, antifungal, and antiviral(Batovska et al.,
2007; Lahtchev et al., 2008; Trivedi et al., 2007; Chimenti
et al., 2009).
Keywords 20-Hydroxy-40,60-diisoprenyloxychalcone ꢀ
Synthesis ꢀ Antidepressant activity ꢀ Chemical induced test
In recent years, it has been reported that flavonoids pos-
sessed the antidepressant activities (Yi et al., 2008; Wang
et al., 2008; Machado et al., 2008; Paulke et al., 2008; An
et al., 2008; Zhao et al., 2011a). In our previous study, several
differently substituted flavanone and chalcone deriva-
tives exhibited the antidepressant activities. Among these,
(40-methoxy-5,7,30-trihydroxyflavanone (compound 1) and
2-bromo-20,40,60-trihydroxychalcone (compound 2) showed
maximum antidepressant activity with significantly reduced
times during the forced swimming test (FST) at a dose of
10 mg/kg (Zhao et al., 2011a; Sui et al., 2012) (Fig. 1).
The prenyl fragment is featured widely in many drugs
and natural products (Zhao et al., 2011b; Winans et al.,
1999).The isoamyl alkenyl group is an important group that
exhibits a wide variety of pharmacological effects, for
instance, anti-oxidative, anti-inflammatory, and anti-tumor
(Vogel et al., 2008, 2010; Rao et al., 2009). In our search
L.-P. Guan (&) ꢀ Y. Chang ꢀ Y. Sun ꢀ J.-F. Jiang
Food and Pharmacy College, Zhejiang Ocean University,
Zhoushan 316000, Zhejiang, People’s Republic of China
e-mail: glp730@yahoo.com.cn
D.-H. Zhao (&)
Jilin Medical College, Jilin City 132013, Jilin,
People’s Republic of China
e-mail: zdh1027@sina.com
Y. Chang
College of Pharmacy, Yanbian University,
Yanji 133000, Jilin, People’s Republic of China
X.-L. Ding
Department of Chemical and Environmental Science,
Kashigar Teacher’s College, Kashigar 844007,
People’s Republic of China
123

Med Chem Res
OH
HP1100LC (Agilent Technologies, USA). The major
chemicals were purchased from Aldrich Chemical Corpo-
ration. All other chemicals were of the analytical grade.
HO
OH
O
HO
O
O
OCH3
OH
Br
OH
General procedure for the preparation
of compounds (4a–4n)
2
1
In a 100 mL round-bottomed flask, to a stirred solution of
compounds 3a–3n (substituted-2,4,6-trihydroxychalcone)
(0.4 mmol) in 30 mL methanol and added to anhydrous
K2CO3 (1.60 mmol) methanol solution. The mixture was
stirred at 50 °C for 1 h, then was slowly added to prenyl
bromide (0.58 mmol and 4 mL anhydrous acetone). The
mixture was refluxed for 8–10 h after the completion of the
reaction (monitored by TLC). K2CO3 was filtered and washed
with acetone. After concentration under reduced pressure, the
resultant was recrystallized from ethanol. The yield, melting
point, and spectral data of each compound are given below.
O
OH
O
A
B
R
O
4a-4n
Fig. 1 Previous work compounds 1, 2 and present study
for the new compounds with the antidepressant effects,
introduction of an isoprenyl group to the 40,60-position on
A-ring of compound 2 was carried out and led to the
production of compounds 4a–4n. The underlying hypoth-
esis was that introduction of a substituted isoprenyloxy
group would increase the lipophilic property of these
compounds and increase their permeability across the
blood–brain barrier, which would probably enhance their
antidepressant activity (Fig. 1).
20-Hydroxy-40,60-diisoprenyloxychalcone (4a) Mp 76.4 °C;
yield = 78.4 %; 1H-NMR (CDCl3, 300 MHz): d 1.60
(s, 3H, –CH3), 1.69 (s, 3H, –CH3), 1.74 (s, 3H, –CH3), 1.77
(s, 3H, –CH3), 4.47 (d, 2H, –CH2), 4.54 (d, 2H, –CH2), 5.41
(t, 1H, =CH), 5.55 (t, 1H, =CH), 6.04–6.08 (m, 2H, –C6H2),
7.52 (d, 1H, J = 15 Hz, =CH), 7.19–7.36 (m, 5H, –C6H5),
8.02 (d, 1H, J = 15 Hz, =CH), 14.18 (s, 1H, –OH); 13C-
NMR (CDCl3, 300 MHz): 18.7, 18.9, 25.2, 25.4, 65.3, 65.6,
95.3, 97.1, 102.9, 121.6, 123.5, 123.9, 126.5, 126.8, 128.1,
128.4, 128.8, 132.1, 132.3, 135.4, 145.2, 163.5, 163.6,
168.6, 190.5; IR (KBr) cm-1: 3314, 1645, 1589, 1220, 968;
MS m/z 393 (M?1).
Reports on the antidepressant-like effects of the structural
derivatives of 20-hydroxy-40,60-diisoprenyloxychalcone are
lacking. So a series of 20-hydroxy-40,60-diisoprenyloxychal-
cone derivatives were designated and synthesized in this
paper. The antidepressant activities of the synthesized
compounds were also determined using the FST (Porsolt
et al., 1977; Porsolt, 1981) and the tail suspension test (TST)
(Steru et al. 1985). The monoaminergic system is one of the
most important targets in the pathophysiology and thera-
pies for depression (Elhwuegi, 2004; Millan, 2004). Two
behavioral models were used to investigate the possible
monoaminergic participation in the antidepressant effect of
the compounds 4e, 4g.
4-Fluoro-20-hydroxy-40,60-diisoprenyloxychalcone (4b) Mp
101.2–102.1 °C; yield = 67.5 %; 1H-NMR (CDCl3,
300 MHz): d1.60 (s, 3H, –CH3), 1.69 (s, 3H, –CH3), 1.74
(s, 3H, –CH3), 1.76 (s, 3H, –CH3), 4.49 (d, 2H, –CH2), 4.53
(d, 2H, –CH2), 5.39 (t, 1H, =CH), 5.52 (t, 1H, =CH),
5.93–6.96 (m, 2H, –C6H2), 7.48 (d, 1H, J = 15 Hz, =CH),
7.02–7.76 (m, 4H, –C6H4), 7.80 (d, 1H, J = 15 Hz, =CH),
14.13 (s, 1H, –OH); 13C-NMR (CDCl3, 300 MHz): 18.5,
18.7, 25.1, 25.5, 65.6, 65.8, 95.1, 96.9, 102.5, 114.9, 115.1,
121.2, 123.3, 123.7, 128.2, 128.5, 130.2, 132.1, 132.3, 145.5,
162.3, 163.6, 163.7, 168.7, 191.5; IR (KBr) cm-1: 3313,
1645, 1586, 1220, 969; MS m/z411 (M?1).
Experimental methods
Chemistry
4–Chloro-20-hydroxy-40,60-diisoprenyloxychalcone (4c) Mp
117.5–119.2 °C; yield = 81.3 %; 1H-NMR (CDCl3,
300 MHz): d1.60 (s, 3H, –CH3), 1.70 (s, 3H, –CH3), 1.74
(s, 3H, –CH3), 1.77 (s, 3H, –CH3), 4.50 (d, 2H, –CH2), 4.53
(d, 2H, –CH2), 5.39 (t, 1H, =CH), 5.52 (t, 1H, =CH), 5.93-
7.19 (m, 2H, –C6H2), 7.58 (d, 1H, J = 15 Hz, =CH),
7.20–7.43 (m, 4H, –C6H4), 7.94 (d, 1H, J = 15 Hz, =CH),
14.10 (s, 1H, –OH); 13C-NMR (CDCl3, 300 MHz): 19.0,
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 and 13C-NMR
spectras were measured on an AV-300 (Bruker, Switzer-
land), and all chemical shifts were given in ppm relative
to tetramethylsilane. Mass spectra were measured on an
123

Med Chem Res
19.1, 25.4, 25.7, 65.2, 65.3, 94.5, 95.6, 102.3, 121.5, 123.2,
123.9, 127.3, 127.5, 128.6, 128.8, 132.4, 132.6, 133.4,
114.7, 121.2, 123.5, 123.8, 127.4, 127.6, 132.3, 132.6,
145.7, 159.6, 163.5, 163.7, 168.7, 190.7; IR (KBr) cm-1
:
133.9, 145.4, 163.3, 163.5, 168.8, 190.3; IR (KBr) cm-1
:
3314, 1645, 1585, 1221, 970; MS m/z 423 (M?1).
3312, 1644, 1585, 1220, 970; MS m/z 427 (M?1).
4-Dimethylamine-20-hydroxy-40,60-diisoprenyloxychalcone
1
4-Bromo-20-hydroxy-40,60-diisoprenyloxychalcone (4d) Oil;
yield = 85 %; 1H-NMR (CDCl3, 300 MHz): d1.59 (s, 3H,
–CH3), 1.68 (s, 3H, –CH3), 1.74 (s, 3H, –CH3), 1.78 (s, 3H,
–CH3), 4.46 (d, 2H, –CH2), 4.51 (d, 2H, –CH2), 5.45 (t, 1H,
=CH), 5.54 (t, 1H, =CH), 5.92–6.03 (m, 2H, –C6H2), 7.56
(d, 1H, J = 15 Hz, =CH), 7.19–7.44 (m, 4H, –C6H4), 7.94
(d, 1H, J = 15 Hz, =CH), 14.11 (s, 1H, –OH); 13C-NMR
(CDCl3, 300 MHz): 19.1, 19.3, 25.6, 25.8, 65.1, 65.4, 93.5,
94.6, 102.5, 121.4, 122.5, 123.4, 123.6, 128.4, 128.6, 131.4,
131.7, 132.2, 132.4, 134.6, 145.6, 163.5, 163.7, 168.7,
190.2; IR (KBr) cm-1: 3314, 1647, 1589, 1221, 970; MS
m/z 471 (M?1).
(4h) Oil; yield = 75.7 %; H-NMR (CDCl3, 300 MHz):
d1.63 (s, 3H, –CH3), 1.72 (s, 3H, –CH3), 1.75 (s, 3H,
–CH3), 1.78 (s, 3H, –CH3), 2.98 (s, 3H, –NCH3), 2.99 (s,
3H, –NCH3), 4.29 (d, 2H, –CH2), 4.48 (d, 2H, –CH2), 4.87
(t, 1H, =CH), 4.90 (t, 1H, =CH), 6.58–7.19 (m, 2H,
–C6H2), 7.76 (d, 1H, J = 15 Hz, =CH), 7.20-7.52 (m, 4H,
–C6H4), 7.93 (d, 1H, J = 15 Hz, =CH), 13.29 (s, 1H,
–OH);13C-NMR (CDCl3, 300 MHz): 18.7, 18.9, 25.6, 25.8,
40.4, 40.6, 65.0, 65.3, 94.2, 95.4, 102.3, 114.1, 114.4,
121.7, 123.6, 123.7, 127.1, 127.4, 132.0, 132.4, 145.1,
148.6, 163.0, 163.3, 168.9, 189.7; IR (KBr) cm-1: 3316,
1652, 1586, 1221, 969; MS m/z 436 (M?1).
2,4-Dichloro-20-hydroxy-40,60-diisoprenyloxychalcone (4e) Mp
98.9–99.4 °C; yield = 76 %; 1H-NMR (CDCl3, 300 MHz):
d1.60 (s, 3H, –CH3), 1.67 (s, 3H, –CH3), 1.69 (s, 3H,
–CH3), 1.73 (s, 3H, –CH3), 4.48 (d, 2H, –CH2), 4.53 (d, 2H,
–CH2), 5.40 (t, 1H, =CH), 5.49 (t, 1H, =CH), 5.92-7.14
(m, 2H, –C6H2), 7.53 (d, 1H, J = 15 Hz, =CH), 7.20–7.43
(m, 3H, –C6H3), 7.93 (d, 1H, J = 15 Hz, =CH), 13.97 (s, 1H,
–OH); 13C-NMR (CDCl3, 300 MHz): 19.5, 19.6, 25.2, 25.6,
65.3, 65.5, 93.3, 94.9, 102.1, 121.6, 123.2, 123.7, 126.4,
129.6, 130.2, 131.3, 132.1, 132.3, 132.7, 134.8, 145.3, 163.6,
163.9, 168.8, 189.9; IR (KBr) cm-1: 3313, 1645, 1587, 1220,
968; MS m/z 461 (M?1).
3-Methoxyl-20,4-dihydroxy-40,60-diisoprenyloxychalcone
(4i) Mp 70.5–72.9 °C; yield = 70.4 %; 1H-NMR
(CDCl3, 300 MHz): d1.62 (s, 3H, –CH3), 1.68 (s, 3H,
–CH3), 1.72 (s, 3H, –CH3), 1.79 (s, 3H, –CH3), 3.89 (s, 3H,
–OCH3), 4.49 (d, 2H, –CH2), 4.86 (d, 2H, –CH2), 5.23 (t,
1H, =CH), 5.37 (t, 1H, =CH), 6.67-7.15 (m, 2H, –C6H2),
7.56 (d, 1H, J = 15 Hz, =CH), 6.89-7.07 (m, 3H, –C6H3),
7.88 (d, 1H, J = 15 Hz, =CH), 13.11 (s, 1H, –OH);13C-
NMR (CDCl3, 300 MHz): 19.3, 19.5, 25.3, 25.5, 55.8,
64.9, 65.3, 93.6, 94.9, 102.5, 112.1, 116.3, 120.8, 121.4,
123.3, 123.5, 128.4, 132.4, 132.6, 144.6, 145.6, 151.6,
163.2, 163.5, 168.8, 190.7; IR (KBr) cm-1: 3310, 1648,
1587, 1220, 969; MS m/z 439 (M?1).
4-Methyl-20-hydroxy-40,60-diisoprenyloxychalcone (4f) Mp
95.2–96.3 °C; yield = 80.4 %; 1H-NMR (CDCl3, 300 MHz):
d1.61 (s, 3H, –CH3), 1.71 (s, 3H, –CH3), 1.74 (s, 3H, –CH3),
1.77 (s, 3H, –CH3), 2.30 (s, 3H, –CH3), 4.53 (d, 2H, –CH2),
4.57(d, 2H, –CH2), 5.32 (t, 1H, =CH), 5.51 (t, 1H, =CH), 5.93-
7.14 (m, 2H, –C6H2), 7.55 (d, 1H, J = 15 Hz, =CH),
7.18–7.50 (m, 4H, –C6H4), 7.91 (d, 1H, J = 15 Hz, =CH),
13.15 (s, 1H, –OH);13C-NMR (CDCl3, 300 MHz): 19.4, 19.6,
24.4, 25.5, 25.8, 65.4, 65.7, 93.8, 94.5, 102.4, 121.6, 123.6,
123.7, 126.4, 126.6, 129.4, 129.6, 132.1, 132.2, 132.5, 137.6,
145.3, 163.2, 163.6, 168.9, 190.4; IR (KBr) cm-1: 3314, 1653,
1594, 1221, 970; MS m/z 407 (M?1).
3-Nitro-20-hydroxy-40,60-diisoprenyloxychalcone (4j) Mp
68.4–70.1 °C; yield = 64 %; 1H-NMR (CDCl3, 300 MHz):
d1.61 (s, 3H, –CH3), 1.68 (s, 3H, –CH3), 1.75 (s, 3H, –CH3),
1.78 (s, 3H, –CH3), 4.48 (d, 2H, –CH2), 4.52 (d, 2H, –CH2),
5.42 (t, 1H, =CH), 5.54 (t, 1H, =CH), 5.94–7.07 (m, 2H,
–C6H2), 7.54 (d, 1H, J = 15 Hz, =CH), 7.48–8.17 (m, 4H,
–C6H4), 8.22 (d, 1H, J = 15 Hz, =CH), 14.15 (s, 1H, –OH);
13C-NMR (CDCl3, 300 MHz): 18.6, 19.0, 25.3, 25.5, 65.3,
65.5, 93.5, 94.8, 102.5, 120.4, 121.2, 121.5, 123.6, 123.8,
129.7, 132.1, 132.3, 132.5, 136.6, 145.3, 148.7, 163.3, 163.5,
169.1, 191.4; IR (KBr) cm-1: 3313, 1653, 1594, 1220, 965;
MS m/z 438 (M?1).
4-Methoxyl-20-hydroxy-40,60-diisoprenyloxychalcone (4g)
1
Oil; yield = 69.8 %; H-NMR (CDCl3, 300 MHz): d1.63
20-Hydroxy-4,
40,60-triisoprenyloxychalcone
(4k) Mp
(s, 3H, –CH3), 1.71 (s, 3H, –CH3), 1.75 (s, 3H, –CH3), 1.79
(s, 3H, –CH3), 3.79 (s, 3H, –OCH3), 4.48 (d, 2H, –CH2),
4.56 (d, 2H, –CH2), 4.93 (t, 1H, =CH), 5.54 (t, 1H, =CH),
6.63-7.19 (m, 2H, –C6H2), 7.57 (d, 1H, J = 15 Hz, =CH),
7.20-7.50 (m, 4H, –C6H4), 7.80 (d, 1H, J = 15 Hz, =CH),
13.10 (s, 1H, –OH); 13C-NMR (CDCl3, 300 MHz): 19.1,
19.4, 25.2, 25.5, 55.5, 65.2, 65.5, 94.0, 95.1, 102.7, 114.3,
102.4–104.8 °C; yield = 83.2 %; 1H-NMR (CDCl3,
300 MHz): d1.60–1.92 (m, 18H, –CH3), 4.42–4.50 (m, 6H,
–CH2), 5.40–5.45 (m, 3H, =CH), 5.93–7.19 (m, 2H, –C6H2),
7.46 (d, 1H, J = 15 Hz, =CH), 6.82–6.91 (m, 4H, –C6H4),
7.63 (d, 1H, J = 15 Hz, =CH), 14.13 (s, 1H, –OH); 13C-
NMR (CDCl3, 300 MHz): 18.6, 18.8, 19.3, 25.4, 25.6, 25.9,
65.0, 65.2, 65.7, 94.6, 95.8, 102.5, 114.3, 114.4, 121.5, 123.1,
123

Med Chem Res
123.3, 123.6, 127.2, 127.4, 127.6, 132.0, 132.1, 132.4, 145.3,
159.6, 163.3, 163.6, 170.1, 191.3; IR (KBr) cm-1: 3312,
1652, 1590, 1221, 967; MS m/z 477 (M?1).
water. They were housed in groups of six. On the test day, mice
were dropped one at a time into a plexiglass cylinder (height
25 cm, diameter 10 cm) containing 10 cm of water at
22–25 °C. When testing, mice were assigned into different
groups (n = 10 for each group). The synthesized compounds
(10 mg/kg) and fluoxetine as a reference antidepressant drug
(10 mg/kg) were dissolved in DMSO through injection intra-
peritoneally (ip) in a standard volume of 0.05 mL/20 g body
weight, 30 min prior to the test. Then, the mice were dropped
individually into the plexiglass cylinder and left in the water
for 6 min. After the first 2 min of the initial vigorous strug-
gling, the animals were immobile. A mouse was judged
immobile if it floated in the water in an upright position and
made only slight movements in order to prevent sinking. The
duration of immobility was recorded during the last 4 min of
the 6 min test. Immobility period was regarded as the time
spent by the mouse floating in the water without struggling and
making only those movements necessary to keep its head
above the water. Following swimming sessions, they were
then towel dried and returned to their housing condition. The
animals were used only once in this test. All FSTs were per-
formed between 10:00 a.m. and 18:00 p.m.
20-Hydroxy-3,4,40,60-treisoprenyloxychalcone
(4l) Oil;
yield = 79 %; 1H-NMR (CDCl3, 300 MHz): d1.60–1.97
(m, 24H, –CH3), 4.51–4.82 (m, 8H, –CH2), 5.42–5.54 (m,
4H, =CH), 5.93–7.19 (m, 2H, –C6H2), 7.61 (d, 1H,
J = 15 Hz, =CH), 6.78–7.09 (m, 3H, –C6H3), 7.82 (d, 1H,
J = 15 Hz, =CH), 14.15 (s, 1H, –OH); 13C-NMR (CDCl3,
300 MHz): 18.6, 18.7, 19.0, 19.3, 25.3, 25.5, 25.6, 25.8,
65.0, 65.3, 65.5, 70.2, 94.0, 95.1, 102.2, 111.4, 115.3,
119.6, 121.3, 123.0, 123.0, 123.7, 123.9, 128.6, 132.0,
132.1, 132.4, 132.6, 145.3, 148.3, 149.1, 149.8, 163.5,
163.7, 170.3, 191.6; IR (KBr) cm-1: 3314, 1648, 1589,
1222, 966; MS m/z 561 (M?1).
3-(Furan-2-yl)-1-(20-hydroxy-40,60-diisoprenyloxy)phenyl)
prop-2-en-1-one (4m) Oil; yield = 61 %; 1H-NMR (CDCl3,
300 MHz): d1.61 (s, 3H, –CH3), 1.69 (s, 3H, –CH3), 1.73
(s, 3H, –CH3), 1.76 (s, 3H, –CH3), 4.47 (d, 2H, –CH2), 4.50
(d, 2H, –CH2), 5.45 (t, 1H, =CH), 5.56 (t, 1H, =CH),
6.07–7.14 (m, 2H, –C6H2), 7.48 (d, 1H, J = 15 Hz, =CH),
7.08–7.75 (m, 3H, –furan), 7.87 (d, 1H, J = 15 Hz, =CH),
14.10 (s, 1H, –OH); 13C-NMR (CDCl3, 300 MHz): 18.3,
18.7, 24.7, 24.9, 65.1, 65.2, 94.6, 98.7, 101.2, 103.1, 111.1,
112.8, 123.1, 123.6, 127.5, 130.9, 131.4, 144.5, 152.6,
162.3, 163.8, 167.4, 190.2; IR (KBr) cm-1: 3312, 1656,
1565, 1220, 961; MS m/z 383 (M?1).
Tail suspension test (TST)
The TST was based on the method of Steru (Steru et al.
1985). Briefly, each mouse was individually suspended by
its tail using a clamp (2 cm from the end) for 6 min in a
box (25 9 25 9 30 cm) with the head 5 cm from the
bottom. Testing was carried out in a darkened room with
minimal background noise. On testing, mice were assigned
into different groups (n = 10 for each group). The syn-
thesized compounds (10 mg/kg) and fluoxetine as a refer-
ence antidepressant drug (10 mg/kg) were dissolved in
DMSO injected ip in a standard volume of 0.05 mL/20 g
body weight, 30 min prior to the test. After the first 2 min
of the initial vigorous struggling, the animals were
immobile. The duration of immobility was recorded during
the last 4 min of the 6 min test. All test sessions were
recorded by a video camera positioned directly above the
box. Two competent observers blind to treatment scored
the videotapes. Mice were considered immobile only when
they hung passively and were completely motionless. The
animals were used only once in this test. All TSTs were
performed between 13:00 p.m. and 15:00 p.m.
1-(20-Hydroxy-40,60-diisoprenyloxy)phenyl)-3-(naphthalen-
2-yl)prop-2-en-1-one (4n) Mp 131.5–132.5 °C; yield =
84.7 %; 1H-NMR (CDCl3, 300 MHz): d1.61 (s, 3H, –CH3),
1.69 (s, 3H, –CH3), 1.71 (s, 3H, –CH3), 1.75 (s, 3H, –CH3),
4.04 (d, 2H, –CH2), 4.48 (d, 2H, –CH2), 5.42 (t, 1H, =CH),
5.54 (t, 1H, =CH), 5.93-7.07 (m, 2H, –C6H2), 8.06 (d, 1H,
J = 15 Hz, =CH), 7.38–7.87 (m, 7H, –naphthalen), 8.55
(d, 1H, J = 15 Hz, =CH), 14.42 (s, 1H, –OH); 13C-NMR
(CDCl3, 300 MHz): 19.1, 19.3, 25.1, 25.0, 65.6, 65.4, 93.4,
96.4, 103.3, 120.6, 121.5, 123.1, 123.4, 123.7, 125.5,
126.5, 126.8, 127.3, 128.3, 128.6, 132.4, 132.7, 133.4,
133.6, 145.5, 163.5, 163.7, 168.7, 190.4; IR (KBr) cm-1
:
3316, 1647, 1589, 1220, 965; MS m/z 443 (M?1).
Pharmacology
Forced swimming test (FST)
5-Hydroxytryptophan (5-HTP) induced mouse head-twitch
test
The FST used was the same as described in detail elsewhere by
Porsolt (Porsolt et al., 1977; Porsolt, 1981). The synthesized
compounds were screened for their antidepressant activities.
Local breed, male Kunming mice (20–24 g) were used in the
FST under standard conditions with free access to food and
To investigate whether the serotonergic system was
involved in the antidepressant-like effect of compounds 4e,
4g, we performed a 5-HTP-induced head-twitch test (Hanna
123

Med Chem Res
Statistical analysis
et al., 2007; Goodwin et al., 1984). Totally 24 male Kun-
ming (20–25 g) mice were randomly chosen and divided
into three groups as normal control group, group of com-
pounds 4e, 4g, and fluoxetine. Mice were administered an ip
injection with compounds 4e, 4g (30 mg/kg), fluoxetine
(30 mg/kg) and were dissolved in DMSO injected ip in a
standard volume of 0.05 mL/20 g body weight, 60 min
before 5-HTP (100 mg/kg, ip). Immediately after the sec-
ond injection, mice were placed into plastic cages. Ten
minutes later, the cumulative number of head twitches
(rapid movements of the head with little or no involvement
of the trunk) was recorded for 6 min. All test sessions were
recorded by a video camera. The animals were used only
once in this test; the head-twitch tests were performed
between 13:00 p.m. and 16:00.
Results are expressed as mean SEM; n represents the
number of animals. Data obtained from pharmacological
experiments were analyzed with one-way analysis of var-
iance (ANOVA) followed by Dunnet’s post hoc test, using
Pharmacologic Calculation System Version 4.1. (Micro-
computer Specialists). A p value of less than 0.05 was
considered statistically significant.
Results and discussion
Chemistry
The target compounds 4a–4n were synthesized according
to Scheme 1. Compound 1 was a key substrate for the
subsequent reactions and was prepared by an established
procedure (Sui et al., 2012). Briefly, the starting material
1-(2,4,6-trihydroxyphenyl)ethanone reacted with chol-
oro(methoxy)methane in acetone to yield compound 1.
Then, the intermediates 2a–2n were synthesized by the
Claisen–Schmidt condensation reaction from compound 1,
with appropriate aromatic aldehydes, protected as chloro-
methyl methyl ether in (Nishida et al., 2007). Compounds
3a–3n were obtained through the intermediates 2a–2n
reacted with 3 M HCl in methanol (Zhao et al., 2005;
2010). Finally, the latter compounds subsequently under-
went a substitution reaction with prenyl bromide in acetone
on heating under reflux to give the title compounds 4a–4n.
Yohimbine toxicity potentiation test
To reveal whether the noradrenergic system is involved in
the antidepressant-like effect of compounds 4e, 4g, the
yohimbine toxicity potentiation test was performed (Hanna
et al., 2007). Totally 40 male Kunming (20–25 g) mice
were randomly chosen and divided into four groups: nor-
mal control group, group of compounds 4e, 4g, and clo-
mipramine; compounds 4e, 4g, and clomipramine (30 mg/
kg) were dissolved in DMSO injected ip in a standard
volume of 0.05 mL/20 g body weight, 1 h prior to
yohimbine administration (20 mg/kg, s.c.). The number of
dead mice was calculated during a 24 h period after the
injection of yohimbine.
OH
Scheme 1 Synthesis routes of
target compounds 4a–4n
O
O
O
HO
OH
O
O
O
O
OH
O
ii
R
i
CH3
CH3
O
O
OH
O
1
2a-2n
O
OH
OH
HO
R
iiii
iii
R
O
O
OH
O
4a-4n
3a-3n
R:
4a = H
4b = 4-F
4g = 4-OCH3
4l = 3,4-[OCH2CH=C(CH3)2]2
4c =4-Cl
4d = 4-Br
4e = 2,4-Cl2
4f = 4-CH3
4h = 4-N(CH3)2
4i = 3-OCH3-4-OH 4j = 3-NO2
4k = 4-OCH2CH=C(CH3)2
O
4m =
4n =
Reagents and conditions:
(i) ClCH2OCH3, K2CO3, acetone; (ii) aromatic aldehyde, KOH, EtOH; (iii) 3 M HCl, MeOH; (iv) prenyl
bromide, K2CO3 anhydrous, acetone.
123

Med Chem Res
150
100
Pharmacology
The FST and the TST were designed by Porsolt et al. and
Steru et al. as primary screening tests for antidepressant
activity and are behavioral tests used to predict the efficacy
of antidepressant treatment (Porsolt et al., 1977; Porsolt,
1981; Steru et al., 1985). It remains one of the best models
for this purpose for several reasons. It is used effectively in
predicting the activity of a wide variety of antidepressant
activities and is a low-cost, fast and reliable model to test
potential antidepressant treatments with a strong predictive
validity. The immobility time observed in the test reflects a
state of lowered mood or hopelessness in animals; thus,
these models are the most widely used tool for preclinical
screening of the putative antidepressant agents and have
good predictive value for antidepressant potency in humans
(Bourin et al., 2005; Petit-Demouliere et al., 2005).
50
0
Control FLU
4b
4c
4h
4i
4j
4k
4l
4m
Fig. 3 Effects of the acute treatment with compounds (10 mg/kg)
and FLU (10 mg/kg ip) on the immobility time in the forced
swimming test. Each column represents the mean SEM. *p \ 0.05
as compared to control (all comparisons were made by ANOVA
followed by Dunnett’s test)
The performance of compounds 4a–4n and the reference
drug fluoxetine in the FST test are presented in Figs. 2 and
3. The pharmacological results exhibited that six com-
pounds significantly reduced the duration of the immobility
time at 10 mg/kg, compared with the control group
showing better antidepressant activity. Acute treatment
with compounds 4a, 4d–4g, and 4n promoted a significant
decrease in the immobility time in the FST at 10 mg/kg, as
depicted in Fig. 2. (control = 116.7 12.3; 4a = 78.7
18.8; 4d = 72 11; 4e = 77.0 8.9; 4f = 79.3 16.8;
4g = 84.7 8.3; 4n = 73.3 16.6; fluoxetine = 68.6
8.3). The immobility time of mice treated with com-
pounds 4b, 4c, 4h–4l, and 4m did not statistically differ
from the control values as shown in Fig. 3 (control =
116.7 12.3; 4b = 97.7 16.4; 4c = 92.2 16.2; 4h =
Among the derivatives, three compounds, 4d (4-bromo-
20-hydroxy-40,60-diisoprenyloxychalcone), 4e (2,4-dichloro-20-
hydroxy-40,60-diisoprenyloxychalcone), 4g (4-methoxyl-
20-hydroxy-40,60-diisoprenyloxychalcone) were found to
possess maximum antidepressant activity, and significantly
reduced the duration of immobility times to 10 mg/kg dose
levelwhencomparedtothecontrol(p\0.001), which reduced
immobility time by 38.3, 34.0, and 27.4 %, respectively.
The structure–activity relationship of compounds 4a–4n
was analyzed using their activity in the FST test. Generally,
the activity of an organic compound might be increased after
the introduction of a halogen atom. So, some halogen-
substituted derivatives were designed and synthesized in this
paper. Analyzing the antidepressant activity of the synthe-
sized compounds 4b–4e, the following SAR was gained.
The halogen-substituted derivatives (4b–4e), compounds
except 4b, 4e displayed the antidepressant activity in the
FST. The atom Br gave more contribution to the antide-
pressant activity than atoms F and Cl, the rank of the activity
order of halogen-substituted derivatives was Br[ F[Cl.
Among these, compounds 4d and 4e showed maximum
antidepressant activity in FST, with reduced immobility time
by 38.3 and 34.0 % at 10 mg/kg, respectively. Next, the
position of halogen substituted on the phenyl ring greatly
influenced the antidepressant activity, compared with
compounds with different Cl-substituted positions on phenyl
ring; the rank of activity order was 2,4–Cl2 [ 4–Cl.
The contribution order of the electron-donor group to the
antidepressant activity (Fig. 2), is 4–OCH3 [ 4–CH3 [
–H[ 4-N(CH3)2. However, introduction of an isoprenyl
group to the 3,4-position on B-ring led to the production of
compounds 4k, 4l, which did not show the antidepressant
activity. In addition, compared with two aromatic hetero-
cyclic compounds (4m, 4n) were also designed and
110.8 19.8;
4i = 102.0 15.5;
4j = 98.5 16.8;
4k = 110.5 16.8; 4l = 96.8 14.9; 4m = 103.8 15.6;
fluoxetine = 68.6 8.3).
150
100
50
0
Control FLU
4a
4d
4e
4f
4g
4n
Fig. 2 Effects of the acute treatment with compounds (10 mg/kg)
and FLU (10 mg/kg ip) on the immobility time in the forced
swimming test. Each column represents the mean SEM.
**p \ 0.01, ***p \ 0.001 as compared to control (all comparisons
were made by ANOVA followed by Dunnett’s test)
123

Med Chem Res
150
100
50
synthesized. The pharmacological test revealed that the
compound 4n had better antidepressant activity at 10
mg/kg dose level compared with the control (p \ 0.01)
(Figs. 2, 3).
The immobility in the FST was significantly reduced
after treatment with better activity compounds 4d, 4e, and
4g, similar to the positive fluoxetine, as shown in Fig. 4,
indicating a significant antidepressant-like effect. The
decrease in immobility time in the TST showed similarity
to that seen in the FST. Compounds 4d, 4e, and 4g showed
significantly the antidepressant activity and promoted a
significant decrease in the immobility time at 10 mg/kg
(control = 130.5 9.6; 4d = 106.3 19.2; 4e = 88.0
16.6; 4g = 86.7 18.7; fluoxetine = 75.6 8.3). Both
FST and TST are the accepted stress models of depression.
Immobility has been shown to reflect a state of ‘behavioral
despair and variants’ or ‘failure to adapt to stress’ (Bourin
et al., 2005). Immobility displayed in both of these
behavioral despair models has been hypothesized to reflect
behavioral despair which in turn may reflect depressive
disorders in human. There was a significant correlation
between clinical potency and the potency of antidepressant
in both models. The compounds 4d, 4e, and 4g, produced
significantly antidepressant-like activity in both the FST
and TST in mice, which indicates that compounds 4d, 4e,
and 4g possess some antidepressant effects.
0
Control
FLU
4d
4e
4g
Fig. 4 Immobility time of compounds 4d, 4e, and 4g in mouse TST.
Data expressed as mean SEM (n = 10). Statistical analysis of data
was carried out by one-way analysis of variance followed by the t test.
*p \ 0.05, ***p \ 0.001 vs. control
Table 1 Effects of compound 4e, 4g and fluoxetine on the number of
5-HTP-induced head twitches in mice
Compounds
Dose
(mg/kg)
5-HTP
(mg/kg)
Number of
head twitches
4e
30
30
30
–
100
100
100
100
36.5 12.4*
38.1 10.7*
42.7 11.3**
15.7 5.2
4g
Fluoxetine
Control
Values are the mean SEM. (n = 10)
Significantly different compared with control (Dunnett’s test:
*p \ 0.05, **p \ 0.01)
In the present research, two behavioral models were
used to investigate the possible monoaminergic participa-
tion of the effect of the antidepressant activity. Compounds
4e and 4g, as the most active compounds, were chosen for
these tests. Compounds 4e and 4g increased significantly
the cumulative number of head twitches (p \ 0.05 vs.
control) in the 5-HTP-induced mouse head-twitch test,
whereas they enhance the mouse lethality (p \ 0.05 vs.
control) induced by yohimbine. The results indicated that
the serotonergic, but not the noradrenergic system, was
involved in the antidepressant-like effect of compounds 4e
and 4g (Tables 1, 2).
Table 2 Effects of compounds 4e, 4g and clomipramine on yohim-
bine-induced toxicity (mortality) in mice
Compound
Dose
(mg/kg)
Yohimbine
(mg/kg)
Lethality
Total
Mortality
(%)
4e
30
30
30
–
20
20
20
20
10
10
10
10
70*
60*
80*
20
4g
Clomipramine
Control
Several lines of evidence indicate that serotonergic,
dopaminergic, and noradrenergic neurotransmissions are
involved in the expression of the antidepressant-like effect
in the behavioral despair models of depression (Schechter
et al., 2005). Many antidepressant drugs exert their effects
by modulating those neurotransmission system (Richelson,
2002; Corne et al., 1963). The 5-HTP-induced mouse head-
twitch test is an effective method to evaluate serotonergic
effects of drugs in vivo (Lapin, 1980). It has been generally
accepted that numbers of head twitches represent the level
of 5-HT in the synapses. Yohimbine, an a2-adrenergic
release by its antagonistic action on the presynaptic
a2-adrenoceptor. The yohimbine toxicity potentiation test
is usually used for the evaluation of noradrenergic effect of
antidepressants (Deng et al., 2012).
Values are the mean SEM. (n = 10)
Significantly different compared with control (Fisher’s exact test:
*p \ 0.05)
Conclusion
In conclusion, a series of 20-hydroxy-40,60-diisoprenyloxy-
chalcone derivatives were synthesized and their antide-
pressant activities were evaluated using the FST. The
pharmacological results showed that six compounds sig-
nificantly reduced immobility times during the FST at
10 mg/kg, thereby suggesting the antidepressant activity.
Among these, three compounds 4d, 4e, and 4g showed
better antidepressant activity. In addition, in the 5-HTP-induced
123

Med Chem Res
in mice: evidence for the involvement of the serotonergic and
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head-twitch test and yohimbine-induced mortality test,
compounds 4e and 4g could increase the rate of head-
twitching and increase the prevalence of mortality. The
mechanism of the action of the antidepressant effects may
be related to 5-HT and NE. Further studies should be ini-
tiated to reveal the mechanism of action of the antide-
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Acknowledgments This study was supported by the National Nat-
ural Science Foundation of China (No. 30960458), the Natural Sci-
ence Foundation of Zhejiang Province of China (No. LY12C19005).
Zhejiang Marine Biotechnology Innovation Team (ZMBIT) (2010
R50029).
¨
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