Advances in Bioscience and Biotechnology, 2011, 2, 108-116 ABB
doi:10.4236/abb.2011.22017 Published Online April 2011 (http://www.SciRP.org/journal/abb/).
Published Online April 2011 in SciRes. http://www.scirp.org/journal/ABB
Antidepressant and cognitive activities of intranasal
piperine-encapsulated liposomes
Aroonsri Priprem1*, Pennapa Chonpathompikunlert2, Saengrawee Sutthiparinyanont3,
Jintanaporn Wattanathor n4
1Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, Thailand;
2Department of Physiology (Neuroscience Graduate Program), Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand;
3School of Pharmaceutical Sciences, University of Phayao, Phayao, Thailand;
4Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
Received 20 January 2011; revised 8 March 2011; accepted 20 March 2011.
ABSTRACT
Antidepressant and cognitive effects of piperine-en-
capsulated liposomes (PL) were investigated in male
Wistar rats. Oral piperine (5 mg/kg body weight/day)
and intranasal PL (7.2 µg/day) were randomly as-
signed to daily administer for 14 days to rats which
were subjected to forced swimming, Morris water
maze and spontaneous motor behavior tests. PL sig-
nificantly exhibited anti-depression like activity and
cognitive enhancing effects, in comparison to the con-
trol groups after the first dose (p < 0.01) and the ef-
fects could be maintained throughout the period of
study. Quantitative analysis of the brain homogenates
by HPLC indicated that piperine, delivered either
orally or nasally, distributed to the hippocampus at a
higher extent than the cortex and that the time to
peak concentration of nasal PL was shorter than for
the oral piperine. Intranasal PL was, thus, potential
in delivery of piperine, at a low dose, to exert its an-
tidepressant and cognitive enhancing activities.
Keywords: Piperine Liposome; Anti-Depression
Activity; Cognitive Enhancement Effect; Intranasal
Route
1. INTRODUCTION
Piperine, a major alkaloid of black pepper (Piper ni-
grum Linn.) and long pepper (Piper longum Linn.), has
been used in folk medicine for the treatment of various
diseases, including seizure disorders [1-3]. Pharmacol-
ogical studies have shown that piperine possesses
various activities including anti-inflammatory and an-
algesic [4], anticonvulsant [5], anti-ulcer [6], anti-de-
pressant [1], cytoprotection, antioxidant [7] and cogni-
tive enhancing effect [8]. It inhibits monoamine oxi-
dase (MAO) activity [1,3,9] and increases the level of
noradrenaline and serotonin in mouse brain [3], indi-
cating its potential neurological benefits. Piperine
could affect hippocampal neurogenesis in chronic mild
stressed mice in which the level of brain-derived neu-
rotrophic factor decreased. At a dose between 5 - 20
mg/kg body weight given to cholinergic-deficient rats,
induced by AF64A, piperine could attenuate the in-
crease in lipid peroxidation and acetylcholinesterase
activity [10]. Results from cell survival and the level of
brain-derived neurotrophic factor in corticosterone-treated
cultured hippocampal neurons confirm similar findings
[11], yet the mechanism of actions of piperine on neu-
ronal damage is still unknown.
The toxicity of piperine has been reported at an oral
dose of 10 and 20 mg/kg body weight for 30 days
[12,13], particularly effects on male reproductive sys-
tem and irritation to the skin and eye. 47% - 64% of an
oral dose of piperine would be subjected to the
first-pass effect [14] with some distribution to other
organs. To exert its neuropharmacological actions, high
doses of piperine are thus required, yet, safety is also a
major concern particularly in long-term use. Nanopar-
ticles decrease toxicity of therapeutic drugs by over-
coming the blood brain barrier (BBB) which limits
brain delivery from the central compartment [15]. Lipid
nanospheres which encapsulated piperine lowered its
clearance rate and reduced its volume of distribution
[16]. Thus, to deliver potentially toxic substances using
nanosize particles might lower the doses as well as
toxicity when compared to conventional dosage forms.
Liposomes could be prepared into nanosize vesicles
(20 - 100 nm) formed by phospholipids and similar
amphipathic lipids. Lipid bilayers of liposomes are
similar in structure to those found in living cell mem-
branes and can carry lipophilic substances such as

A. Priprem et al. / Advances in Bioscience and Biotechnology 2 (2011) 108-116 109
drugs within these layers in the same way as cell mem-
branes. This would facilitate drug transport and release
across the BBB. A nerve growth factor, encapsulated in
100-nm liposomes, was protected from enzyme degra-
dation in vivo and enhanced permeability across the
BBB [17]. Proteins or peptide drugs could be delivered
to the endothelial cells of brain capillary with a specific
target to the lysosomes by encapsulation in liposomes
[18].
Nasal administration, bypassing the BBB [19], offers
a potential direct transfer of substances from the olfac-
tory mucosa along the olfactory pathway to the central
nervous system [20,21]. Drug absorption along the ol-
factory membrane, dependent on the characteristics of
the compounds, is possible for systemic effect due to
high degree of vascularization of the nasal mucosa and
neuronal cells exposure which may facilitate transpor-
tation to the cerebrospinal fluid [22]. Hydrophobic
compounds might diffuse or retrograde transport along
the axon to the olfactory bulbs and diffuse to the rest of
the brain. This could be relatively slow and ineffective
in terms of drug usage. Hydrophilic compounds might
transport into the cerebrospinal fluid via the subarach-
noid space which extends along the olfactory nerves to
the basolateral side of the olfactory epithelium. The
intranasal route of several drugs was comparable to
parenteral administration [23-25] with rapid brain de-
livery and first-pass avoidance [26]. Limitations include
hydrophilic, labile and irritating compounds. Due to
physiological limitation, the volume to be instilled into
the nasal cavity for optimal effect is suggested to be less
than 0.25 ml. Also, bioadhesive materials are suggested
to overcome rapid mucociliary clearance which could
decrease absorption [24,27-28]. Thus, this manuscript
investigates piperine-encapsulated liposomes for brain
delivery with polymers used to retain the liposomal
dispersion inside the nasal cavity. Dose reduction when
a compound is given in liposomal forms is expected
[15,29], thus, for piperine, a lower dose was estimated
and proposed for the first time in this study.
To study the effect of piperine delivery on the anti-
depressant and cognitive actions in animals, several
recognized and well-established tests using animal
models were used. The Morris water maze (MWM) test
is an effective model for investigation of cognitive ef-
fects because the deficits in (hidden-plat-form) MWM
performance could relate to the intellectual decline in
human Alzheimer patients [30]. The forced swimming
test is used in screening of anti-depressant activity [31].
Stereotyped behaviors, a group of repetitive and invariant
behaviors are used to indicate psychological well-being
related to the living environment, as follows: grooming
indicating a hygienic activity of predictable sequence
of activities directed to the animal body surface [32]
which involves the function of dopamine receptors,
especially D1 and D2 [33,34]; rearing behavior, ex-
pressed by rising hind legs without front paws touching
any surface, associated with the selective elevation of
striatal glutamate (Glu) and aspartate (Asp) concentra-
tions [35] and dopamine [36]; licking behavior, involved
the alteration of the transmitter function such as dopa-
mine [37] and serotonin [38].
From our previous study [8], oral piperine has shown to
be effective as a cognitive enhancing compound. Oral
administration of piperine involves first-pass metabolism
and relatively high doses which could lead to adverse
side effects or other undesired consequences. This study
intended to develop an intranasal delivery of piperine
using a form of encapsulation in liposomes and study
depression and cognition effects in animal models by
comparison to the conventional oral piperine. The in-
tranasal dose of piperine was proposed. It was hypothe-
sized that both treatments would deliver piperine to exert
the desire activities in the brain.
2. MATERIALS AND METHODS
2.1. Materials
High-purity egg L-α-phosphatidylcholine (EPC), piper-
ine and potassium chloride (Sigma-Aldrich, Germany),
cholesterol (chol, Sigma-Aldrich, Japan), potassium
phosphate monobasic, (KH2PO4, Sigma-Aldrich, U.S.A.)
and polyethylene glycol 1000 (PEG, Sigma, Spain) were
used. Analytical or HPLC grade solvents, such as chlo-
roform, absolute ethanol, acetonitrile and orthophos-
phoric acid, were from BDH Laboratory Supplies (Poole,
England). Heparin sodium was obtained from LEO
Pharmaceutical Products (Denmark). Deionized water
was used throughout this study. All chemicals were used
as received.
2.2. Piperine-Encapsulated Liposomes
Thin film hydration with extrusion [39-41] was the method
of choice in the preparation of piperine-encapsulated lipo-
somes (PL) used in this study. In brief, a lipid film was
formed during degassing and moderate rotation at 60ºC
using a 1:2 molar ratio of EPC and chol in the presence
of piperine and chloroform. Subsequently, it was hy-
drated with water (about 60ºC), sonicated, extruded (Li-
posoFast, Avestin, Canada) twice through 0.2-µm and
then 0.1 µm polycarbonate membranes (Avestin, Canada)
and mixed with propylene glycol and PEG. The PL,
contained 0.6 mg/ml of piperine, were freshly-prepared
using aseptic technique throughout the study. Transmis-
sion electron microscope (TEM, Joel JEM 2010, JEOL
Co. Ltd., Tokyo, Japan) was used to view the PL. Per-
centage encapsulation efficiency (%EE) of piperine in the

A. Priprem et al. / Advances in Bioscience and Biotechnology 2 (2011) 108-116 110
liposomes was estimated by the following Eq.1:
100
tol free
tol
CC
%C 





(1)
where EE is the entrapment efficiency, Ctol is total quan-
tity of added piperine and Cfree is quantity of free piper-
ine detected from supernatant.
2.3. Animal
Adult male Wistar rats (n = 8, 180 - 220 g, 8 weeks old)
were obtained from the National Animal Center, Nakorn
Pathom, Thailand. Male rats were recommended because
of the advantage in spatial learning [30]. Upon arrival,
they were housed in standard metal cages (5 each) at
21ºC ± 1ºC and 65% relative humidity with a 10 h
light/14 h dark cycle and given standard chow and water
ad libitum for the duration of the study. They were al-
lowed 2 weeks to adapt to their environment before use
in this experiment.
The rats were randomly assigned into four groups, i.e.
oral piperine, intranasal PL, vehicle, and blank lipo-
somes, containing eight animals per group in each ex-
periment. Each animal was subjected to the behavioral
assessment at a predetermined period. The experiments
were conducted following the approved protocol by the
Ethics Committee of the institute which minimized the
number of animals used in the study, also attempts were
made to minimize animal suffering in accordance with
the internationally accepted principles for laboratory use
and care of the European Community (EEC Directive of
1986; 86/609/EEC).
Prior to determine the dose of PL, estimation from the
pharmacokinetic profile of piperine and preliminary
study was thoroughly investigated. PL with a concentra-
tion of piperine of 0.6 mg/ml was administered to each
rat once daily at dose of 48 ng/kg body weight by drop-
ping into the right nasal cavity. During and for 20 sec
after the nasal drop, the rat was gently hold upright to
ensure that the PL contacted the nasal mucosa and
moved into the deeper part of the nasal cavity. Animals
in conventional piperine group were subjected to intra-
gastric administration of freshly-prepared piperine solu-
tion in propylene glycol once daily at a dose of 5 mg/kg
body weight. Care was taken to conduct each experiment
at the same period of the day to avoid deviations in ani-
mal behavior.
2.4. Behavioral Assessments
Each rat was assessed by Morris water maze (MWM)
and forced swimming tests as well as daily spontaneous
motor behavior assessment, as per the following details:
Morris water maze test: The Morris water maze test
was used as a tool to determine cognitive function of the
rats that were trained to memorize the location of the
hidden platform in relation to its location. Animals with
enhanced cognition would be demonstrated by a de-
crease in escape latency and an increase in retention time.
The water maze consisted of a metal pool (170 cm in
diameter × 58 cm tall) filled with tap water (25ºC, 40 cm
deep) divided into four quadrants. In the center of one
quadrant was a removable escape platform which was
placed below the water level. The top of the water was
covered with nontoxic milk powder. The pool was di-
vided into four quadrants (NE, NW, SE, and SW) by two
imaginary lines crossing the center of the pool. For each
animal, the location of invisible platform was placed at
the center of one quadrant and remained there through-
out training. The rats must memorize the platform loca-
tion in relation to various environmental cues because
there was nothing directly showing the location of the
escape platform in or outside the pool. Therefore, the
placement of the water tank and platform were the same
in all acquisition trials. Each rat was gently placed in the
water facing the wall of the pool from one of the four
starting points (N, E, S, or W) along the perimeter of the
pool, and the animal was allowed to swim until it found
and climbed onto the platform. During the training ses-
sion, the rat was gently placed on the platform by ex-
perimenter if it could not reach the platform within 60
sec. In either case, the subject was left on the platform
for 15 sec and then removed from the pool. The time for
animals to climb onto the hidden platform was recorded
as escape latency or acquisition time. In order to deter-
mine the capability of the animals to retrieve and retain
information, the platform was removed 24 h later and the
rat was released into the quadrant diagonally opposite to
that which contained the platform. Time spent in the
region that previously contained the platform was re-
corded as retention time. In each trial, the animal was
quickly dried with a towel before being returned to the
cage.
Preliminary studies were conducted to organize the
series of each test in the same pattern and timing. Right
after the dosage administration, each set was subjected
to the test within 30 min. This was controlled throughout
the study.
Forced swimming test: In order to assess the anti-de-
pressant activity of the substance, the modified Porsolt
test [42], a valid animal model for testing depression
[31,43], was conducted. Animals with depression would
demonstrate an increase in immobility and also a decrease
in active behavior (swimming, moving or climbing). Each
rat was subjected to the behavior test, before and at pre-
determined period after the treatment, during a 5 min
session in water, contained in a cylindrical glass aquar-
ium (22 cm in diameter, 40 cm in height), at a depth of

A. Priprem et al. / Advances in Bioscience and Biotechnology 2 (2011) 108-116 111
20 cm and 25ºC ± 1ºC. The same trained observer, blinded
from the intervention given to each rat, timed and recorded
the durations that each rat spent on immobility, swim-
ming and climbing throughout the 5 min session. The
rats were considered immobile when neither of the hind
leg was moving; the rats were slightly hunched forward.
The total duration of immobility was measured during
the 5-minutes test. Upon removal from the water, rats
were towel-dried and finally returned to their home cage.
Spontaneous motor behavior assessment: In order to
assure that anti-depression like activity and cognitive
enhancing effect which were determined by various tests
mentioned earlier were not false positive due to the ef-
fect of piperine on motor behavior, we also determined
the effect of piperine on the spontaneous locomotor ac-
tivity. All animals were assessed for spontaneous motor
behavior including grooming and rearing licking behavior
[44] for 5 min. The performance was determined 60 min
after substance administration.
2.5. Quantitative Analysis of Piperine in the
Brain Homogenate by HPLC
The HPLC system: An HPLC with a UV/VIS detector
(Perkin Elmer 200 IC, U.S.A.), a C18 column (4.6 mm ×
250 mm, 5 µm, Theale Reading, Berks, U.K.) and Data
Apex Charity Lite software was used. A mobile phase
consisting of 1:1 of acetonitrile in 0.01 M KH2PO4 and
adjusted to pH 4.5 using orthophosphoric acid was used
at a flow rate of 1.0 ml/min, and detection was at 340 nm.
Piperine standards were freshly-prepared by diluting
from a stock solution in absolute ethanol to a concentra-
tion range of 2 - 100 ng/ml with mobile phase. The
standards showed good linear correlation and accuracy
with an average %CV of less than 15%.
Brain homogenate: The cortex and hippocampus
parts of the brain of each rat were isolated after it was
anaesthetized and sacrificed. Each brain tissue was ho-
mogenized with 0.2 ml of 1.15% KCl [45]. The ho-
mogenate was then thoroughly mixed with 0.3 ml of the
HPLC mobile phase and centrifuged at 10,000 rpm for
30 min (Spectrafuge, U.S.A.). The supernatant was
separated for HPLC analysis. Each data was obtained
from three individuals with triplicate analyses from each.
2.6. Statistical Analysis
Data are presented as means ± S.E.M. Statistical analysis
was performed by one-way analysis of variance. A
probability value of less than 0.05 was considered sig-
nificant.
3. RESULTS AND DISCUSSION
Figures 1, 2 and 3 demonstrate that the results obtained
from the rats treated with the vehicle, composed of pro-
(a) Escape latency time
(b) Retention time
Figure 1. Morris water maze test of 5 groups of rats meas-
ured after a single dose or repeated once-daily doses at 1st
and 2nd weeks; the control (clear column), treatment with
vehicle (grey column), blank liposomes (black column), pi-
perine 5 mg/kg body weight (horizontal stripes column) and
piperine-encapsulated liposomes (vertical stripes column),
each being a mean ± S.E.M. (n = 8 each), #p < 0.001 com-
pared with vehicle or blank liposomes.
pylene glycol, PEG and water, or the blank liposomes,
composed of EPC, chol, and the vehicle, used in this
study were not significantly different from the results
obtained from the relevant control groups (p > 0.05 all).
The dose-dependent toxicity of piperine has been well
reported, and thus, the oral dose of piperine was deter-
mined by following that reported by Wattanathorn et al.
(2008) [8]. The intranasal dose was then proposed by
estimation from its oral dose and pharmacokinetic pro-
file reported earlier [8], based on minimal or none
first-pass metabolism involvement on nasal absorption.
Spatial memory of the rats was assessed by MWM
test and is shown in Figure 1(a) escape latency and 1(b)
retention time. A 3-fold decrease in average escape laten-
cies was observed, i.e. from 14.7 ± 2.9 to 5.4 ± 1.2 and
13.7 ± 0.6 to 4.9 ± 0.7 sec after single doses of oral

A. Priprem et al. / Advances in Bioscience and Biotechnology 2 (2011) 108-116 112
(a) Swimming duration
(b) Climbing duration
Figure 2. Forced swimming test of 5 groups of rats measured
after a single dose or repeated once-daily doses at 1st and 2nd
weeks; the control (clear), treatment with vehicle (grey),
blank liposomes (dark), piperine 5 mg/kg body weight (hori-
zontal stripes) and piperine-encapsulated liposomes (vertical
stripes), each being a mean ± S.E.M. (n = 8 each), #p < 0.001
compared with vehicle or blank liposomes.
piperine and intranasal PL, respectively. This pattern of
reduction was also observed after repeated daily doses
for 1 and 2 weeks. Figure 1(b) showed an increase in
the retention time, from 10.9 ± 1.7 to 16.4 ± 1.1 and 11.1
± 0.5 to 21.8 ± 0.7 sec after single doses of oral piperine
and intranasal PL, respectively. Both results, escape la-
tency reduction and retention time increase, were sig-
nificantly different (p < 0.001) from the control, vehicle
and blank liposome groups. The results of the oral pi-
perine group and intranasal PL group, however, were not
statistically different (p > 0.05). These indicate that oral
piperine and intranasal PL enhanced cognitive function
in the rats when compared to the non-treatment groups.
Forced swimming is a behavioral test used frequently
to evaluate the potential efficacy of prospective antide-
pressant drugs in rats or mice [42]. Its principle lies on
the fact that, while forced swimming, a test compound
exerts its antidepressant by decreasing immobility time
(a) Grooming behavior
(b) Rearing behavior
(c) Licking behavior
Figure 3. Spontaneous motor behavior test of 5 groups of rats
measured after a single dose or repeated once-daily doses at 1st
and 2nd weeks; the control (clear column), treatment with vehi-
cle (grey column), blank liposomes (black column), oral
piperine 5 mg/kg body weight (horizontal stripes column) and
piperine-encapsulated liposomes (vertical stripes column),
each being a mean ± S.E.M. (n = 8 each).
and increasing active behaviors, which should be consis-
tent with a therapeutic effect of increasing escape-directed
activities [46]. Immersion of rodents in the water for an
extended period of time produces a characteristic behavior
called immobility, in which the rat makes only those
movements necessary to keep its head above water.

A. Priprem et al. / Advances in Bioscience and Biotechnology 2 (2011) 108-116 113
Figures 2(a) and 2(b) demonstrate that the PL treated
rats significantly enhanced behavioral mobility, shown
as the swimming times (p < 0.001), and climbing times
(p < 0.01), after single dose of administration, 1 and 2
weeks of treatments. Oral piperine also gave similar re-
sults. Lee et al. [1] using tail suspension test in mice to
investigate the effect of piperine on monoamine oxidase
activity, reported that piperine decreased the immobility
time in a dose-dependent manner at doses of 3 and 9 mg/kg
body weight when given by intra-peritoneal injection.
Because antidepressant activity of a compound usually
enhances behavioral mobility [47], our results suggest
that piperine, regardless of the delivery routes and dos-
age, inhibited depression-like behaviors in rats which
were assessed by forced swimming test.
In order to prove that the reduction of immobility time
in the force swimming test did not associate with a
non-specific increase in locomotor activity or even de-
crease motor behavior in open field tests [31], we inves-
tigated the spontaneous motor activity induced by piper-
ine in a separate experiment. The results were shown in
Figure 3. In this study, both forms of piperine and the
vehicles at doses which produced an antidepressant-like
effect, did not significantly change spontaneous motor
behavior including grooming, licking and rearing be-
havior (p > 0.05, all). This result demonstrated that the
antidepressant-like effect of piperine in the MWM test
was not based on any stimulation of locomotor activity.
Since the spontaneous motor behaviors of the test
animals did not indicate that piperine affected any motor
function of the brain, it affirmed that the anti-depression
like activity and cognitive enhancing effects which were
determined by force swimming and MWM tests were
not affected in the presence of piperine at these doses.
Piperine from the oral liquid and the intranasal lipo-
somes, thus, has been shown to exert anti-depression and
cognitive enhancing effects.
Figure 4 illustrates PLs which were small round par-
ticles surrounding with clusters of polymeric coating. By
observation, the size of the liposomes with polymeric
coating was about 100 nm. The encapsulation efficiency
of the liposomes, estimated by %EE from 4 batches of
preparations, was found to be 65 ± 3.6%. This indicates
a moderate encapsulation which could be due to the hy-
drophobic characteristics of piperine. Coating with PEG
was intended to enhance viscosity as well as assist the
adherence of liposomal particles to the nasal mucosa.
This might have facilitated the intranasal absorption of
piperine into the brain and effectively showed activities
at a daily dose of 48 ng/kg body weight.
Figure 5 compares the piperine content time course of
two delivery systems in two portions of the brain issues,
namely the hippocampus and the cortex. The content of
Figure 4. TEM photograph of piperine-encap su-
lated liposomes with PEG coating.
(a)
(b)
Figure 5. Piperine content extracted after administration of (a)
oral piperine (5 mg/kg body weight) and (b) nasal piperine
liposomes (0.048 mg/kg body weight) at time interval from the
brain tissues: hippocampus (--o--) and cortex (●). The error
bars represent S.E.M. (n = 3 each).
piperine extracted after administration of oral piperine
showed higher levels than nasal piperine liposomes. This

A. Priprem et al. / Advances in Bioscience and Biotechnology 2 (2011) 108-116 114
was anticipated as the oral dose was about 100 times
higher. The duration required to reach maximum brain
levels after oral doses was about 40 - 50 min while that
after nasal doses being 15 min. Intranasal administration
of piperine from this liposome formulation could rapidly
deliver piperine into the brain although at lower levels
than the oral solution. Both delivery systems suggested
uneven distribution of piperine in different brain tissues,
particularly the hippocampus which was the preference
for piperine intake. The results support the behavioral
assessment that piperine exerted its action within the
brain and in the hippocampus, in particular. A
dose-response study was not one of our objectives but
our findings lead to imply that the dose needed for the
brain activities of piperine might be less than that used in
the oral doses. However, this needs further evidence.
In comparison to the previous study of Wattanathorn
et al. [8] which employed an oral dose of 5 mg/kg body
weight, this study showed a reduction of dose used to ob-
tain similar outcome. Piperine, effective as an anti-de-
pressant drug and cognitive enhancing drug, delivered
intranasally in a liposomal encapsulation tends to be
lower dose than from an oral suspension by about 200
times. Also, both anti-depression like and cognitive-
enhancing effects were significantly improved after the
first dose. This emphasizes an importance of the delivery
form of piperine to exert its neurological actions in the
brain.
Lee et al. [1] demonstrated that piperine could re-
versibly inhibited mouse brain MAO-A and MAO-B
activities in a dose-dependent manner at i.p. doses of 3
and 9 mg/kg body weight. Its activity could be compara-
ble to that of fluoxetine, a reference antidepressant agent,
at 10 mg/kg, i.p., and thus, conclude that the antidepres-
sant-like effect of piperine may be mediated through the
enhancement of serotonergic and norepineph-rinegic neu-
rotransmission, as well as by dopaminergic neuro-trans-
mission. However, the mechanism involved in the ob-
served antidepressant activity is not elucidated. This study
confirms its antidepressant activity at a lower dose when
administered by intranasal PL. It is very interesting to
that the anti-depression like activity and cognitive en-
hancing effect of piperine liposome are comparable to
the piperine conventional form [8]. Piperine liposomes
could be reproducibly prepared from EPC/chol at a ratio
of 2:1 and showed antidepressant and cognitive enhanc-
ing effect. The advantages of having a particle size in
nanoscale, entrapment efficiency of about 60%, are that
the liposomes might permeate through the olfactory epi-
thelium and release piperine to exert its actions.
The anti-depression and cognitive enhancing effects
had previously shown to be associated with the alteration
of various neurotransmitters including serotonin [48,49]
and acetylcholine [50] respectively. Intranasal admini-
stration, coupled with liposomal encapsulation facilitated
the delivery of piperine via the olfactory pathway and
might permeate and diffuse into the cerebrospinal fluid
to exert its anti-depression and cognitive enhancing ef-
fects by alteration of acetylcholine and serotonin [2]
respectively.
The results lead us to conclude that intranasal piperine
liposomes could deliver piperine to the brain and poten-
tially benefit for novel treatment of certain neurophar-
macological disorders. Also, its unpleasant odor was
successfully masked and its brain delivery particularly to
the hippocampus was very rapid.
4. CONCLUSIONS
Piperine liposomes, particle sizes of less than 100 nm
with an entrapment efficiency of about 60%, when ad-
ministered intranasally, could deliver piperine to the
brain. Its pungent unpleasant odor was masked with the
liposomal encapsulation and the addition of polymers.
Also, intranasal piperine liposomes were shown to de-
liver to the hippocampus at a faster rate and higher ex-
tent than the oral dose. Intranasal delivery of piperine
from the liposomes could therefore reduce the dose of
piperine intake while giving the similar cognitive and
antidepressant effects as the oral dosage.
5. ACKNOWLEDGEMENTS
This study was partially supported by the National Research Council of
Thailand and the Development of Nutraceuticals and Brain Plasticity
Research Group Khon Kaen University, Khon Kaen 40002.
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