Antidepressant-Like
Effects of the Ethanolic Extract of Albizzia lebbeck
(Linn) Leaves in Animal Models of Depression
Malarkodi Velraj*1, V.
Ravichandiran1, S. Ramamoorthy1, A. Vijayalakshmi1
and J Srikanth2
1Vels University, School of
Pharmaceutical Sciences, Dept. of Pharmacognosy , Pallavaram, Chennai – 600117, Tamil
2Sri
ABSTRACT:
The present study was
designed to investigate the antidepressant effects of Albizzia lebbeck leaves in various animal
depression models. The alcoholic extract
(70% v/v ethanol) of Albizzia lebbeck leaves
(200 and 400 mg/kg. p.o) was administered once daily
for seven successive days to separate groups of young male swiss
albino mice. The immobility periods of control and treated mice were recorded
in two behavioral despair models forced swim test (FST), tail suspension test
(TST) and the effect of extract on locomotor function
of mice was studied using actophotometer. The
antidepressant-like effect of tested drug was compared to that of imipramine (15 mg/kg. p.o) and fluoxetine (20mg/kg.p.o). The leaf extract at doses of 200
and 400 mg/kg significantly decreased the duration of immobility time in a dose
dependent manner in both FST and TST.
The extract did not
show significant effect on locomotor activity of
mice. The efficacy of tested extract was found to be comparable to that of imipramine and fluoxetine. Our
results suggested that the ethanolic extract of Albizzia lebbeck leaves
exerts antidepressant-like effect.
KEYWORDS: Albizzia lebbeck, Depression, Forced swim test, Tail suspension test.
INTRODUCTION:
Depression is a
common, debilitating, life-threatening illness with an increasing morbidity and
mortality. Furthermore, the World Health Organization revealed that depression
is the fourth leading cause of disability worldwide, exceeded by lower
respiratory infections, perinatal conditions and
HIV/AIDS1. Current antidepressant drugs, including various monoamine
reuptake inhibitors and monoamine oxidase inhibitors,
have proven to be effective and are available in clinic, but they are burdened
with such disadvantage as slow onset of action, relatively low response and
side effects, which make the research and development of new type antidepressants
urgent2,3. The antidepressant effect of
herbs has been paid more and more attention gradually because of increasing
incidence of depression and predominance of traditional herbs in therapy.
The plant Albizzia lebbeck Linn
is a large deciduous tree belonging to the family Mimosaceae
4. The plant possess many therapeutic activities such as in the
treatment of leprosy, ulcers, ophthalmic and skin eruptions, skin diseases and
CNS depressant activity 5 .
In the present study, the antidepressant effect of Albizzia lebbeck Linn
leaves was assessed using well accepted and validated experimental paradigms of
depression, so as to provide supportive evidence for the folklore claims.
Therefore, the present study was undertaken
to investigate the effect of Albizzia lebbeck leaves on depression in mice employing forced
swim test (FST) and tail suspension test (TST).
Standard antidepressant drugs such as fluoxetine,
a selective serotonin reuptake inhibitor, and imipramine,
a tricyclic antidepressant were employed to
standardize the animal models of depression and to compare the antidepressant
efficacy of Albizzia lebbeck.
MATERIALS
AND METHODS:
Preparation of extract of Albizzia lebbeck:
The leaves of Albizzia lebbeck was
collected from the field in Meenembakkam, Chennai
district, Tamilnadu, India, in the month of June
2006.The plant specimen for the proposed study was collected from Chennai,
Tamil Nadu. It was identified and authenticated by Dr. Sasikala,
Department of Pharmacognosy, Central Drug research and Siddha
institute, Chennai, where the voucher specimen was deposited (no. 168) in the
Pharmacognosy herbarium, Vels University, India. The
leaves of Albizzia lebbeck Linn
was shade dried and coarsely powdered.
About 500 gm of powder was extracted with ethanol (70% v/v ethanol) by
cold maceration method 6. The solvent was filtered and evaporated on
a rotary evaporator under reduced pressure to obtain a viscous alcoholic
extract. The extract was dried in
vacuum and the percentage yield was 8.5%.
Phytochemical Screening:
The alcoholic extract (70% v/v ethanol) was
screened for the presence of phytoconstituents by
chemical methods 7, from which the extract was found to contain
maximum number of phytoconstituents and was selected
for the pharmacological study.
Acute
toxicity study:
The alcohol extract was used to test the
acute and short-term toxicity in mice (20-25 g body weight) 8. Four
doses (0.25, 0.5, 0.75 and 1.0 gm/ kg) of the alcoholic extract were orally
administrated to different mice groups (n=5 each). For acute toxicity, we
observed mortality and general behavior of the mice for 48 hours. The
parameters observed were grooming, hyperactivity, sedation, loss of righting
reflex, respiratory rate, and convulsion. For the short term toxicity, we used
three mice each. The behavior of the animals was observed daily for one hour in
the forenoon (
Experimental
Animals:
Albino Swiss mice of either sex (20-30 g)
were obtained from Institutional Animal Breeding House,
Drugs
and Chemicals:
Imipramine hydrochloride
(Sigma-Aldrich,
Evaluation of antidepressant
activity:
Forced swim test (FST):
Behaviour despair was proposed
as a model to test for antidepressant activity 9, 10. Animals were
divided in to four groups of six animals each. Normal
control group, receiving a single dose of 0.5 mL/100g of the vehicle. Group 2 reference drug group, being treated
with imipramine (15 mg/kg). Groups 3 and 4 were being
treated with the ethanolic extract at two dose levels
(200 and 400 mg/ kg). The
treatment was continued for seven consecutive days. .On the test day mice
were forced to swim individually in a glass jar (25 x 12 x 25 cm3sub)
containing fresh water of 15 cm height and maintained at 25°C (± 3°C). After an
initial 2 min period of vigorous activity, each animal assumed a typical
immobile posture. A mouse was considered to be immobile when it remained
floating in the water without struggling, making only minimum movements of its
limbs necessary to keep its head above water. The total duration of immobility
was recorded during the next 4 min of a total 6 min test. The changes in
immobility duration were studied after administering drugs in separate groups
of animals. Each animal was used only once.
Tail suspension test (TST):
Animals were divided
in to four groups of six animals each. Normal control group,
receiving a single dose of 0.5 mL/100g of the vehicle. Group 2 reference drug group, being treated
with fluoxetine (20 mg/kg). Groups 3 and 4 were being
treated with the ethanolic extract at two dose levels
(200 and 400 mg/ kg). The treatment was continued for seven consecutive days.
On the test day mice were suspended on the edge of a table 50 cm above the
floor by the adhesive tape placed approximately 1 cm from the tip of the tail.
The total duration of immobility induced by tail suspension was measured as a
facile means of evaluating potential antidepressants 11. Immobility
time was recorded during a 6 min period 12. Animal was considered to
be immobile when it did not show any movement of body and hanged passively.
Study of locomotor
activity using Actophotometer:
Effect of test extract (200 and 400 mg/kg) on
locomotor function of mice was studied using a Actophotometer (INCO, Ambala,
India) to rule out the increase in locomotor
performance of mice. The difference in the locomotor
activity scores was noted before and after the administration of ethanolic extract of Albizzia lebbeck.
Statistical analysis:
Statistical analysis was carried out using
Graph Pad PRISM software (version 4.03). One way ANOVA was used, followed by Dunnet’s multiple comparison tests (2005). A p-values
<0.05 were considered significant.
RESULT:
Phytochemical
screening:
The phytochemical
screening by chemical test showed that the ethanolic
extract showed positive results for steroids, proteins, flavonoids,
tannins, glycosides and carbohydrates.
Table 1:
Effects of ethanol leaf extract of Albizzia lebbeck and imipramine on the forced swimming test in mice
|
Group |
Treatment |
Dose
(mg/kg) |
Duration
of immobility (sec) |
|
Group I |
Control |
0.5ml/100g |
168.8 ± 3.3 |
|
Group II |
Imipramine |
15 |
98.2 ± 2.8** |
|
Group III |
Ethanol extract |
200 |
132.9 ± 5.3* |
|
Group IV |
Ethanol extract |
400 |
106.0 ± 3.6** |
Each
value represents the mean ± SEM of six observations.*p<0.05, **p<0.01 vs. Control (ANOVA followed by
Dunnett’s test).
Table 2:
Effects of ethanol leaf extract of Albizzia lebbeck and imipramine on the tail suspension test in mice
|
Group |
Treatment |
Dose
(mg/kg) |
Duration
of immobility (sec) |
|
Group I |
Control |
0.5ml/100g |
120.2 ± 4.2 |
|
Group II |
Fluoxetine |
20 |
46.6 ± 3.8** |
|
Group III |
Ethanol extract |
200 |
76.2 ± 2.3* |
|
Group IV |
Ethanol extract |
400 |
46.17 ± 4.6** |
Each
value represents the mean ± SEM of six observations.*p<0.05, **p<0.01 vs. Control (ANOVA followed by Dunnett’s test).
Acute
toxicity study:
Acute toxicity was tested up to a high
concentration of 1 g/kg (two times more than the active dose). We note that
even at this dose level, the extract did not exhibit any sign of toxicity.
Effect of ethanolic
leaf extract of Albizzia lebbeck on
the forced swimming tests in mice:
Compared to the control group, the ethanolic extract of Albizzia lebbeck at dose of 200 mg/kg and 400
mg/kg significantly decreased the duration of immobility time in a dose
dependent manner (Table.1). Immobility time was reduced by 16.62% and 35% for
the extract at the dose of 200 and 400 mg/kg respectively and 39% for imipramine at the dose of 15 mg/kg.
Effect
of ethanolic leaf extract of Albizzia lebbeck on the tail suspension tests in
mice:
The results indicated that Albizzia lebbeck
leaves extract administrated
acutely at dose of 200 and 400 mg/kg, significantly decreased the duration of
immobility time in comparison to the control group when mice were tested in the
tail suspension test. The reductions of the immobility time were 33% and 57%
for the extract at 200 and 400 mg/kg respectively.
Effect on locomotor
activity:
There was no
significant effect on locomotor activity of mice (396
± 9.7 and 378.6 ± 5.8) when treated with ethanolic
extract of Albizzia lebbeck leaves
(200 and 400 mg/kg) for seven successive days as compared to control (before
treatment) (430.78 ± 7.3).
DISCUSSION:
The antidepressant effect of herbs has been
paid more attention gradually because of increasing incidence of depression and
predominance of traditional herbs in therapy. The effective components of herbs
that have antidepressant- like effect include flavonoid,
oligosaccharide, polysaccharide, alkaloid and organic acid 13, 14, 15.
In the present study, ethanolic extract of Albizzia lebbeck leaves (200 and 400 mg/kg, p.o.) produced significant antidepressant-like effect in
mice in both FST and TST. Both these models of depression are widely used to screen
new antidepressant drugs 16, 17. These tests are quite sensitive and
relatively specific to all major classes of antidepressant drugs including tricyclics, serotonin-specific reuptake inhibitors,
monoamine oxidase (MAO) inhibitors and atypical 18. In FST, mice are forced to swim in a
restricted space from which they cannot escape, and are induced to a
characteristic behavior of immobility. This behavior reflects a state of
despair that can be reduced by several agents, which are therapeutically effective
in human depression. The TST also induces a state of immobility in animals like
that in FST. This immobility, referred as behavioural
despair in animals, which is claimed to reproduce a condition similar to human
depression 19. It has been argued that the TST is less stressful
than FST and has greater pharmacological sensitivity 20.
The
antidepressant-like effect of ethanolic extract of Albizzia lebbeck leaves
(200 and 400 mg/kg, p.o.) seems not to be associated
with any motor effects, since it did not show significant change in locomotor function of mice as compared to control
indicating that extract had no excitatory or inhibitory action on central
nervous system in effective dose range, which eliminated the probability of
false-positive results in forced swimming test and tail suspension test.
Initial hypothesis of depression was formulated about 40 years ago, proposing
that the main symptoms of depression were due to the functional deficiency of
cerebral monoaminergic transmitters such as norepinephrine (NE), serotonin (5HT), and/or dopamine (DA)
located at synapses 21. As is well known,
synaptic concentration of 5-HT and/or NE can be increased by commercial
antidepressants. The precise mechanisms by which Albizzia lebbeck produced antidepressant-like
effect are not completely understood.
CONCLUSION:
Thus, it may be
concluded that Albizzia lebbeck produced
antidepressant-like effect in mice in both FST and TST. The efficacy of the Albizzia lebbeck was
comparable to that of imipramine and fluoxetine. Further work was necessary to elucidate the
mechanism of action involved in the antidepressant activity of Albizzia lebbeck with
special references to phytochemicals.
The authors have no
conflict of interest to report.
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Received on 21.09.2009
Accepted on 23.11.2009
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Research Journal of Pharmacognosy and Phytochemistry. 2(1): Jan.-Feb. 2010, 30-33