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Effects of Lemongrass (Cymbopogon citratus) Essential Oil Inhalation on Cognitive Performance and Mood in Healthy Women

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Effects of Lemongrass (Cymbopogon citratus) Essential Oil Inhalation on Cognitive Performance and Mood in Healthy Women

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Objective: To evaluate the effects of inhalation of lemongrass (Cymbopogon citratus) essential oil on the cognitive function and mood in healthy female volunteers. Methods: All 30 participants of each group were required to inhale either lemongrass essential oil or a placebo (inactive control oil) for five minutes. Before and after the 5-minuite inhalation period, their cognitive function was assessed with a computerized battery of tests and the mood with a self-rated visual analogue; the blood pressure and heart rate were also measured. Differences in the cognitive function, mood, blood pressure and heart rate between the two groups were analyzed and tested using an independent t-test. Results: After the inhalation, the lemongrass essential oil enhanced their cognitive performance for the domains of the continuity of attention and the quality of memory (P-value = 0.013 and 0.026, respectively), whereas the mood in terms of alertness and calmness was also increased (P-value = 0.001 and 0.035, respectively). However, no significant change in the blood pressure and heart rate was observed. Conclusion: The lemongrass essential oil inhalation could improve the cognitive function and modulate mood of healthy women with no effect on the physiological status. However, the underlying mechanisms of these positive effects still require further studies.
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32 80 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
Effects of Lemongrass (
Cymbopogon citratus
) Essential Oil Inhalation
on Cognitive Performance and Mood in Healthy Women
นิพนธ์ต้นฉบ
Original Article
,  , 

Napatr Sriraksa1*, Maroot Kaewwongse1, Wathita Phachonpai1 and
Thaneeya Hawiset2
1 
2
2 School of Medicine, Mae Fah Luang University, Chiang Rai, Thailand
* ติดต่อผู้นิพนธ์: napatr.sri@gmail.com
* Corresponding author: napatr.sri@gmail.com
วารสารไทยเภสชศาสตร์และวิทยาการสุขภาพ 2561;13(2):80-88.
Thai Pharmaceutical and Health Science Journal 2018;13(2):80-88.
บทคดย่อ
วัตถุประสงค์: 
: 
inactive control
oil5 


 
independent t-test
: 
(P-
value = 0.013  0.026
(P-value = 0.001
 0.035 
:



: Cymbopogon citratus,, , , 

Abstract
Objective: To evaluate the effects of inhalation of lemongrass (Cymbopogon
citratus) essential oil on the cognitive function and mood in healthy female
volunteers. Methods: All 30participants of each group were required to
inhale either lemongrass essential oil or a placebo (inactive control oil)for
five minutes. Before and after the 5-minuite inhalation period, their cognitive
function was assessed with a computerized battery of tests and the mood
with a self-rated visual analogue; the blood pressure and heart rate were
also measured. Differences in the cognitive function, mood, blood pressure
and heart rate between the two groups were analyzed and tested using an
independent t-test. Results: After the inhalation, the lemongrass essential oil
enhanced their cognitive performance for the domains of the continuity of
attention and the quality of memory (P-value = 0.013 and 0.026,
respectively), whereas the mood in terms of alertness and calmness was
also increased (P-value = 0.001 and 0.035, respectively). However, no
significant change in the blood pressure and heart rate was observed.
Conclusion: The lemongrass essential oil inhalation could improve the
cognitive function and modulate mood of healthy women with no effect on
the physiological status. However, the underlying mechanisms of these
positive effects still require further studies.
Keywords: Cymbopogon citratus, lemongrass, essential oil, cognitive
performance, mood
Introduction
Recently, alternative strategies to improve life
performance have come to the fore. A number of
complementary therapies, especially aromatherapy, are
currently employed in the management of various medical
conditions including anxiety, depression, insomnia and stress-
related disorders. Aromatherapy uses essential oils in various
applications including inhalation, massage and baths to alter
mood, cognition, and psychological and/or physical well-being.
The sense of smell begins when odor molecules bind to the
olfactory receptors in the nasal passage. Nerve impulses pass
along the olfactory nerve to the olfactory bulb, primary
olfactory cortex and limbic system, particularly the
hippocampus and amygdaloid body. It is interesting to note
that the hippocampus as well as amygdaloid body are brain
areas that are related to cognitive performance, emotion and
emotional memory.1 Animal studies indicated that some
essential oils produce pharmacological effects on behavior,
effects similar to those of central nervous system drugs.2-4 It
is also well known that aroma inhalation causes physiological
and psychological alterations in humans.5 Previous studies
have demonstrated that different types of aroma produce
significant changes in brain waves, blood pressure, heart rate
and respiratory rate.6,7 In addition, accumulating lines of
evidence have reported that some essential oils such as
lavender and rosemary exert beneficial effects on cognitive
function and mood.8,9
32 81 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
LemongrassCymbopogon citratus), a plant of Poaceae
family, has long been used in Thailand for cooking and
medical purposes. This plant exerts beneficial properties such
as anti-inflammatory, antifungal,10 antinociceptive11 and
antioxidant effects.12 Animal studies show that lemongrass
essential oil has anti-anxiety, sedative and anticonvulsive
effects.13,14 A recent human study demonstrated that
lemongrass essential oil inhalation exerts anxiolytic effects
and reduces subjective tension in male participants who are
exposed to an experimental anxiogenic situation.15 However,
the effects of lemongrass essential oil inhalation on the
nervous system, particularly as a cognitive enhancer and
mood modulator in young female participants, have not been
studied. Therefore, we set up this experiment to elucidate this
issue. Specifically, we aimed to compare cognitive functions
(power of attention, continuity of attention, quality of memory,
and speed of memory), mood (alertness, calmness and
contentment), and physiological function (diastolic blood
pressure, systolic blood pressure, and heart rate) between
those inhaling lemongrass essential oil and placebo oil post-
inhalation.
Methods
Participants
Sixty healthy female volunteers (mean age SD: 20.52
0.60, age range: 20 22 years) took part in this experiment,
all of whom provided written informed consent. This study was
approved by the Human Ethics Committee of the University of
Phayao (5701040001). Participants were excluded if they had
significant visual impairment, motor impairment, cognitive
impairment, or underlying health problem (e.g. allergy,
respiratory tract infection, sinusitis, a cold, hypertension or
cardiac disorder). Participants with a history of drug abuse,
alcohol abuse or prescribed/non-prescribed drug regimen(s)
were excluded. In addition, participants who regularly
consumed nutraceutical compounds known to influence the
function of the nervous system were also excluded. If a
participant was with her menstruation, she was asked to wait
until her period was passed beforeparticipating. All
participants were asked not to consume caffeine or alcohol for
12 hours before participating.
Preparation of lemongrass essential oil and placebo oils
The lemongrass essential oil was purchased from
Botanicessence, Bangkok, Thailand. It was extracted from
lemongrass fresh leaves using a hydrodistillation method. As
verified by our preliminary study (data not shown), extra virgin
coconut oil obtained from a drug store was used as the
placebo. Before testing, one drop (50 µL) of lemongrass
essential oil or coconut oil was placed in an amber glass bottle
containing sterilized cotton. The bottle was then promptly
closed and remained closed until the experimental procedure
began.
Analysis of the lemongrass essential oil component
The organic compounds of the lemongrass essential oil
were analyzed using gas chromatographymass spectrometry
(GCMS) which was provided by the Scientific and
Technological Instruments Center of Mae Fah Luang
University. The GCMS analysis was performed according to
the following conditions. The capillary column (HP-5 ms) was
used with the flow rate of 1 ml/min. The oven temperature of
the gas chromatograph was set at 40 240 °C. Hexane was
used as the solvent. The temperature of the injector and
detector was set at 250 °C and 230 °C, respectively. The
mass spectrometer was set to determine a molecular weight
range of 20 300. The components were identified by their
fragmentation patterns of mass spectra compared with data
from the National Institute of Standards and Technology Mass
Spectra database (NIST08). The identified constituents of the
lemongrass essential oil determined by GCMS are shown in
Table 1. The two main chemical components of the
lemongrass essential oil were geranial (28.31%) and neral
(26.15%). The other compounds that were found are in a
lesser amount.
Procedures
Participants in this double-blinded study were assigned to
the lemongrass or placebo group using randomized numbers
generated by a computer. The evaluation of cognition was
assessed using a cognitive computerized battery of tests while
mood state was assessed using a self-rated mood visual
analogue scale. The assessments of cognitive function and
mood state were performed prior to the trial and immediately
after completing the 5-minuite inhalation period. After being
randomly assigned to the lemongrass or placebo group, each
participant inhaled lemongrass essential oil or a placebo for 5
32 82 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
minutes in a quiet experimental room. Immediately after the
5-minute duration, the cognitive performance and mood state
of the participants were assessed again. In addition, the
alterations of blood pressure and heart rate were monitored
before (baseline) and after the 5-minuite inhalation period. The
age, bodyweight, height, body mass index (BMI) and grade
point average (GPA) of all participants were also recorded.
Table 1 Main chemical constituents of lemongrass essential
oil determined by GCMS.
Identified constituents
Area (%)
Retention
time (min)
Geranial
28.31
20.36
Neral
26.15
19.50
2,6-Octadiene, 1,1-diethoxy-3,7-dimethyl
10.26
24.33
2-Butenoic acid
7.66
23.68
Geraniol
2.86
22.75
Bicyclo hexan-3-ol
2.48
17.03
Linalool
2.28
14.63
Naphthalene
1.80
26.03
Geranyllinalool
1.59
36.32
Geranylgeraniol
1.23
36.79
3-Cyclopentene-1-acetaldehyde, 2,2,3-trimethyl
1.05
11.16
Caryophyllene oxide
1.04
27.71
Camphene
0.92
9.90
Citronellal
0.78
16.10
Phenol
0.66
24.58
Cyclohexanemethanol
0.64
26.89
Bicyclo[2.2.2]octane
0.59
16.47
3-Methyl-2-butenal
0.58
18.16
Eucalyptol
0.56
12.39
4-Nonanone
0.49
13.66
Cognitive computerized battery of tests
The cognitive computerized battery of tests used in this
study was modified from the cognitive drug research
computerized test battery that has been widely used to assess
the cognitive function. This test is comprised of a battery of
cognitive tasks sensitive to the effect of
psychopharmacological substances. All tasks in the battery
were computer-controlled and displayed on high-resolution
monitors. The responses were recorded via yes/no buttons.
The participants completed the selected battery in
approximately 20 minutes. The cognitive tests were
administered in the following order.
1) Word presentation: Fifteen words were presented
consecutively on the monitor, each for 1 second, with an inter-
stimulus interval of 1 second. The participants were required
to memorize these words.
2) Picture presentation: Twenty pictures were presented
consecutively on the monitor at a rate of 1 every 3 seconds,
with an inter-stimulus duration of 1 second. The participants
were required to memorize these pictures.
3) Simple reaction time: The word ‘yes’ was presented on
a monitor with an inter-stimulus interval at a random rate
between 1 and 3.5 seconds. The participants were instructed
to press the ‘yes’ button as quickly as possible when they
observed the word ‘yes.’ Their reaction time was recorded in
milliseconds.
4) Digit vigilance task: A target digit was randomly selected
between 0 and 9. It was persistently displayed on the right
side of a monitor. A series of other random digits (also
between 0 and 9) were then displayed in the center of the
screen at the rate of 80 digits per minute. The participants
were instructed to press the ‘yes’ button as quickly as possible
every time the digit in the random series matched the target
digit. The task lasted approximately 1 minute and there were
15 stimulus matches. The reaction time in milliseconds and
the accuracy percentage were recorded.
5) Choice reaction time: Either the word ‘yes’ or ‘no’ was
displayed on a monitor. The participants were required to
press a ‘yes’ or ‘no’ button as quickly as possible when a
stimulus ‘yes’ or ‘no’ appeared on the monitor. There were 50
trials during which the stimulus ‘yes’ or ‘no’ was randomly
displayed (with equal probability). The inter-stimulus interval
randomly varied between 1 and 3.5 seconds. The reaction
time in milliseconds and the accuracy percentage were
recorded.
6) Spatial working memory: A graphical representation of
a house was presented on a screen with four of its nine
windows lit. The participants were instructed to memorize the
position of the illuminated windows. In 36 subsequent
presentations of the house, one of the windows was
illuminated and the participants had to decide whether or not
the lit window was one of the lit windows in the original
presentation. The participants made their response by
pressing a ‘yes’ or ‘no’ button as quickly as possible. The
mean reaction times in milliseconds and the accuracy
percentage were recorded.
7) Numeric working memory: Five numbers were
presented on the monitor at a rate of one number per second.
A series of 30 numbers were then presented. The participants
32 83 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
had to decide if each of the 30 numbers was in the original
series of five numbers as quickly as possible. Their responses
were recorded with a ‘yes’ or ‘no’ button. The mean reaction
time in milliseconds and the accuracy percentage were
recorded.
8) Delayed word recognition: Fifteen words that were
originally presented to the participants (see 1 above) were
again presented to the participants. However, this time these
words were randomly mixed with 15 new words. For each
word in the newly created set of 30 words, the participants
were asked to indicate if each one was included in the original
set by pressing a ‘yes’ or ‘no’ button as quickly as possible.
The mean reaction time in responding to all 30 words was
recorded. The accuracy percentage (percentage of a score on
30) was also recorded.
9) Delayed picture recognition: Fourteen original pictures
that were originally presented to the participants (see 2 above)
were again presented to the participants. However, this time
they were randomly mixed with six new pictures. For each
picture in the newly created set of 20 pictures, the participants
were asked to indicate if each one was included in the original
set by pressing a ‘yes’ or ‘no’ button as quickly as possible.
The mean reaction time in responding to all 20 pictures was
recorded. The accuracy percentage (percentage of a score on
20) was also recorded.
To minimize any learning effect in assessing working
memory, the set of words and pictures to which participants
were exposed before the inhalation were different from those
after inhalation. However, it was insured that the difficulty level
of the words and pictures for each participant was
comparable.
As demonstrated by Peth-Nui and colleagues,16 we
grouped the various outcomes of cognitive functions listed
above into four domains, namely, power of attention, continuity
of attention, quality of memory, and speed of memory. Power
of attention is defined as attention and
psychomotor/information processing speed measured by
summing reaction times in milliseconds of three attentional
tasks including digit vigilance, simple reaction time, and choice
reaction time. Continuity of attention is a prolonged focus
measured by summing the accuracy percentage of digit
vigilance and choice reaction time. More specifically, 100
percent accuracy across the two tasks would result in a
maximum score of 200. Quality of memory is defined as the
capability to accurately recall various stimuli measured by
summing the accuracy percentage of delayed word
recognition, delayed picture recognition, spatial working
memory, and numeric working memory. One hundred percent
accuracy across the four tasks would generate a maximum
score of 400. Speed of memory is the response speed in
milliseconds to various stimuli measured by summing the
reaction times of the delayed word recognition, delayed
picture recognition, numeric working memory and spatial
working memory tasks.
Mood visual analogue scale
This questionnaire is a subjective measurement consisting
of 16 items each on a 10-cm visual analog scale with
antonyms anchoring the endpoints of each scale. Participants
responded by indicating a subjective position between the
antonyms on the scale. The obtained mood scores were
separated into three factors specifically alertness, calmness
and contentment.17 The alertness factor consisted of the
following items: alertdrowsy, attentivedreamy, lethargic
energetic, muzzyclearheaded, well coordinatedclumsy,
mentally slowquick witted, strongfeeble, interestedbored
and incompetentproficient. Items of calmness factor included
calmexcited and tenserelaxed. Finally, the contentment
factor included contenteddiscontented, troubledtranquil,
happysad, antagonisticfriendly and withdrawnsociable.
Physiological assessment
The blood pressure and heart rate of each respondent
were measured using an automatic blood pressure monitor
(Omron HEM-7200TM) at the baseline and immediately after
essential oil inhalation.
Statistical analysis
Data were presented as mean SD. An independent t-
test was used to compare each measure of cognitive function,
mood and physiological function between the placebo and
lemongrass-treated groups at pre- and post-inhalation.
Statistical significance was regarded at P-value < 0.05.
Results
. Characteristics of participants
The personal information of participants in both groups is
shown in Table 2. No significant differences in mean age,
32 84 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
bodyweight, height, BMI and cumulative GPA between the
groups were observed.
Table 2 Demographic information of participants (N = 60).
Characteristic
Mean SD by groups
t-test
P-value
Placebo (n = 30)
Lemongrass (n = 30)
Age (years)
20.53 ± 0.63
20.50 ± 0.57
0.215
0.831
Bodyweight (kg)
55.90 ± 14.22
56.20 ± 12.45
-0.087
0.931
Height (cm)
160.03 ± 5.71
160.17 ± 5.50
-0.092
0.927
BMI (kg/m2)
21.76 ± 5.00
21.81 ± 4.13
-0.041
0.968
Cumulative GPA
2.39 ± 0.23
2.42 ± 0.262
-0.346
0.731
Note: GPA = grade point average; BMI = body mass index.
Effect of lemongrass essential oil inhalation on cognitive
performance
There was no cross-group significant difference found in
any of the cognitive function baseline measures. The baseline
and post-inhalation scores of cognitive performance
measurements are presented in Table 3. The results revealed
that immediately after completing 5-minute inhalation,
participants who inhaled lemongrass essential oil performed
better than the placebo group in the domains of continuity of
attention and the quality of memory with statistical significance
(P-value = 0.013 and 0.026, respectively). However, the
lemongrass inhalation failed to produce a significant difference
in the domains of power of attention and speed of memory.
Table 3 Effects of lemongrass essential oil inhalation on
cognitive function assessed by cognitive computerized
assessment battery test (N = 60).
Cognitive
domain
Time
Mean SD by groups
t-test
P-value
Placebo
(n = 30)
Lemongrass
(n = 30)
Power of
attention
Baseline
1804.77 ± 240.70
1836.47 ± 262.20
-0.488
0.628
After
1735.03 ± 218.23
1768.07 ± 215.73
-0.590
0.558
Continuity of
attention
Baseline
195.70 ± 4.56
196.33 ± 3.33
-0.615
0.541
After
196.60 ± 3.29
198.53 ± 2.52
-2.559
0.013
Quality of
memory
Baseline
367.60 ± 21.30
368.87 ± 26.69
-0.203
0.840
After
373.27 ± 15.10
380.63 ± 8.99
-2.295
0.026
Speed of
memory
Baseline
5136.83 ± 1017.88
5040.30 ± 576.28
0.452
0.653
After
4500.90 ± 734.72
4453.40 ± 661.56
0.263
0.793
Effect of lemongrass essential oil inhalation on mood
Scores obtained from the mood visual analogue scale are
presented in Table 4. Scores of each mood index at baseline
of the two groups were statistically different. After the
inhalation, however, participants who inhaled lemongrass
essential oil reported significantly higher scores on alertness
and calmness (P-value = 0.001 and 0.035, respectively) but
not contentment.
Table 4 Effects of lemongrass essential oil inhalation on
mood assessed by mood visual analogue scale (N = 60).
Mood index
Time
Mean SD by groups
t-test
P-value
Placebo
(n = 30)
Lemongrass
(n = 30)
Alertness
Baseline
6.24 ± 0.78
6.30 ± 0.81
-0.267
0.790
After
6.34 ± 0.84
7.01 ± 0.64**
-3.486
0.001
Calmness
Baseline
6.27 ± 0.98
6.03 ± 0.87
0.975
0.334
After
6.33 ± 0.82
6.72 ± 0.50*
-2.176
0.035
Contentment
Baseline
7.57 ± 0.56
7.51 ± 0.58
0.364
0.717
After
7.47 ± 0.85
7.57 ± 0.61
-0.557
0.580
Effect of lemongrass essential oil inhalation on
physiological status blood pressure and heart rate
Blood pressure and heart rate were assessed as a
baseline (pre-dose) and immediately after the essential oil
inhalation. As shown in Table 5, there were no significant
changes in both systolic and diastolic blood pressures
between groups both at baseline and after inhalation. In
addition, no significant differences of heart rate were found
between the two groups at both time points.
Table 5 Effects of lemongrass essential oil inhalation on the
alterations of blood pressure and heart rate (N = 60).
Measures
Time
Mean SD by groups
t-test
P-value
Placebo
(n = 30)
Lemongrass
(n = 30)
Systolic
pressure
(mmHg)
Baseline
106.57 ± 8.68
108.90 ± 9.36
-1.001
0.321
After
105.17 ± 9.29
106.53 ± 9.13
-0.575
0.568
Diastolic
pressure
(mmHg)
Baseline
68.93 ± 8.38
66.97 ± 9.17
0.867
0.390
After
68.70 ± 8.80
66.20 ± 6.88
1.226
0.225
Heart rate
(beats/min)
Baseline
85.87 ± 7.38
84.73 ± 8.94
0.536
0.594
After
85.30 ± 10.43
84.73 ± 7.81
0.238
0.813
Discussions and Conclusion
In this study, we focused on cognitive enhancement, mood
modulation and physiological effects of lemongrass essential
oil inhalation compared with placebo in healthy female
adolescents. The results showed that lemongrass essential oil
improved cognitive function in the domains of the continuity
(or accuracy) of attention and the quality of memory, both
evaluated via a cognitive computerized assessment battery
test. The participants who inhaled the lemongrass essential oil
also reported higher self-alertness and calmness assessed via
32 85 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
mood visual analogue scale. However, no significant
difference was found between the two groups regarding the
physiological parameters, i.e., blood pressure and heart rate.
The sense of smell starts when odor molecules bind to
olfactory receptors. The chemical signals are then transduced
into electrical signals and sent to areas of the brain through
the olfactory bulb. The sense of smell is transmitted from the
olfactory bulb to the amygdala and entorhinal cortex.18 The
prefrontal cortex of the brain, particularly the orbitofrontal
cortex, and the limbic system, particularly the hypothalamus,
amygdala and hippocampus have pivotal roles in cognitive
function.19 Functional magnetic resonance imaging (fMRI)
evidence indicates that the amygdala and hippocampus are
the areas of the brain that are responsible for emotional
memory and odor-evoked memory.20 Previous studies
suggested that the prefrontal cortex plays an important role
with respect to working memory.21 Working memory is a
process of the brain that allows for both the temporary storage
and use of a limited amount of information for cognitive tasks.
Working memory involves a central executive system that
controls attention, manipulates visual images as well as stores
and rehearses speech-based information.22 Interestingly, it
was demonstrated that working memory is associated with
dopamine in prefrontal neurons.23 Dopamine is a
neurotransmitter that helps working memory. It was also found
that prefrontal dopamine levels gradually increase when
participants perform a working memory task.24 In addition,
other neurotransmitters including norepinephrine,25
serotonin,26 and acetylcholine27 also play a role on working
memory. Taken together, the cognitive enhancing effect of
lemongrass essential oil inhalation may occur due to two
possible mechanisms including (1) the strengthening of neural
connection between the prefrontal cortex and related brain
areas, and/or (2) the enhancement of neurotransmitters
mentioned earlier. However, we left the identification of which
mechanism for future researchers.
Even though there are protocols outlining the use of
essential oil to improve mood, there is scant scientific
information regarding the effect of lemongrass on mood. The
results of mood in the present study showed that lemongrass
essential oil inhalation increased calmness, a similar outcome
to a previous study reporting that lemongrass essential oil
inhalation reduced anxiety and subjective tension in male
volunteers.15 However, the proportion of subject gender in our
study and the previous works was different. Additionally, the
outcome measurements of the previous works were focused
on psychological parameters (state anxiety, subjective
tension, tranquilization, and sedation) and physiologic
parameters (heart rate and gastrocnemius electromyogram
activity) but not on cognitive performance.
One study demonstrated that the oral administration of
lemongrass essential oil produced a sedative effect in mice.14
Since a sedative effect is related to calmness,5 we anticipated
that lemongrass essential oil would exert a calming effect on
our participants. Nevertheless, our study adds value to the
literature regarding the effects of lemongrass since our subject
pool, method of administrating lemongrass and dependent
variables are different from previous research.
In addition, the participants who inhaled the lemongrass
essential oil reported an increased level of alertness. Alertness
is an aroused state that includes sustaining attention as well
as orienting a response.28 Therefore, we suggested that
alertness induced by lemongrass essential oil inhalation would
be related to the mechanisms that control arousal such as the
sleep-waking system and the hormonal system, particularly
hypothalamopituitaryadrenal axis.
Previous studies have also demonstrated that the
improvement of mood is associated with improved cognitive
functioning.8,29 Ashby and colleagues reported that positive
mood is associated with increased brain dopamine levels and
influences olfaction as well as working memory.30 In addition,
Mitchell and Phillips suggested that the prefrontal cortex plays
an important role in integrating mood with the executive
function.31 The amygdala both receives the olfaction signal
from the olfactory bulb and plays a role in emotion as well as
affective cognition.32 Thus, increased alertness and calmness
might modulate cognitive function partly due to the
strengthening of neurotransmitter levels in the prefrontal
cortex and neural connections with the amygdala. However,
this possible mechanism remains to be investigated.
Our results are in accordance with the study of Tildesley
and coworkers,8 they found that the oral administration of sage
(Salvia lavandulaefolia) exerted the acute modulation of mood
and cognition in healthy young adults. Specifically, Salvia
lavandulaefolia essential oil enhanced “speed of memory” and
“quality of memory,” and also improved all mood factors
(alertness, calmness and contentment). Although the cognitive
results of the present study showed inhaling lemongrass
essential oil enhanced the cognitive performance in the
domains of “continuity of attention” and “the quality of memory”
32 86 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
but failed to improve the domains of “power of attention” and
“speed of memory.” In addition to cognitive results, the
inhalation of lemongrass essential oil improved self-alertness
and calmness but not contentment. However, the routes of
administration and the observation time of our work and the
previous work are different.
It is well known that the inhalation of an aroma leads the
body to respond in at least two different ways. First, a
pharmacological effect involves the interaction between an
aroma molecule and its receptor. Second, a psychological
effect involves a subjective experience to the aroma.5 Due to
the activation on the nervous system, particularly the
autonomic nervous system, both pharmacological and
psychological effects can alter one’s physiological status. The
physiological effect of an aroma can be assessed using
measurements such as blood pressure and heart rate. An
increase in blood pressure and heart rate indicates a
stimulating effect whereas a decrease in blood pressure and
heart rate indicates a sedative effect of the autonomic nervous
system.33 We did not find that the inhalation of lemongrass
essential oil had either one of these effects. It is interesting to
note that such effects were reported using lavender and
rosemary oils.6,7,34 However, the simultaneous recording
system used to measure the effects of lavender and rosemary
was more sophisticated than the simple automatic apparatus
used in this study. Therefore, the assessment method could
have limited our ability to identify any physiological effect.
Recently, Kamkean and coworkers reported that participants
between 18 75 years old who received a massage with
lemongrass oil in a 3-week program showed a greater
reduction in diastolic blood pressure.35 However, the routes of
essential oil administration, age range of participants and the
time of assessment in the previous study and the present
study are different. Therefore, these three factors might
explain the difference between our results and those of
Kamkean.
The pharmacological effect of an essential oil requires the
absorption of volatile compounds into the bloodstream,
resulting in the stimulation of neurons.However, we did not
investigate the absorption of an essential oil in this study.
Nevertheless, the data obtained from GCMS analysis
showed that the lemongrass essential oil was composed
mainly of geranial and neral. This chemical composition is
similar to that found in a previous study on lemongrass tea, in
which the tea exerted an anxiolytic and sedative effect in
mice.14 We suggest further investigation to clarify whether the
active components in lemongrass oil that produce positive
effects in this study are geranial and neral.
It is well recognized that female sex hormones (especially
estrogen) play an important role on cognitive function.36 In
order to avoid the effect of estrogen on cognitive performance
in female participants, we performed the test when the
participants were not having their menstrual period. This
concern is one advantage of our study. In addition, we were
also concerned about the difference in the individual
intelligence of participants. The reason we set the desired
cumulative GPA threshold between 2.00 - 2.50 was because
we wanted to limit our sample of participants to those who
could demonstrate improved cognitive performance. Gender
and age may also influence cognitive function. More
specifically, previous studies have demonstrated that in
adulthood, males are superior at visuospatial and motor tasks
whereas females are better in social cognition and recognition
memory.37,38 It is also well known that older adults have poorer
cognitive function than young adults.39 However, to reduce
error in the experiment, we focused on young healthy female
adults. We also determined the effects of lemongrass
essential oil inhalation on three essential parameters including
pharmacological (cognitive function), psychological (mood)
and physiological (blood pressure and heart rate) effects.
These various parameters are important to include because
they help clarify the types of odors that have either an
advantageous or disadvantageous effect on physiological
function. Even though a simple automatic tool used in
evaluating blood pressure is not as accurate or reliable as
sphygmomanometer and stethoscope in auscultatory method,
the cognitive computerized assessment battery test and mood
visual analogue scale are suitable to test cognitive function
and mood state as implemented by previous studies.8,9,16,17,29
In conclusion, lemongrass essential oil improved cognitive
performance and modulated mood in healthy female
participants. This study provides a scientific basis for further
research on the use of lemongrass essential oil as a cognitive
enhancer and mood modulator.
Acknowledgements
This study was supported by the National Research
Council of Thailand (NRCT) and the University of Phayao. The
authors would like to thank Assoc. Prof. Dr. Jintanaporn
Wattanathorn for providing the cognitive computerized
32 87 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
assessment battery test and Dr. Roger Timothy Callanghan
for proofreading the manuscript.
References
1. Herz RS, Engen T. Odor memory: Review and analysis. Psychon Bull
Rev 1996;3(3):300313.
2. de Almeida RN, Motta SC, de Brito Faturi C, Catallani B, Leite JR.
Anxiolytic-like effects of rose oil inhalation on the elevated plus-maze
test in rats. Pharmacol Biochem Behav 2004;77(2):361364.
3. Chioca LR, Ferro MM, Baretta IP, et al. Anxiolytic-like effect of lavender
essential oil inhalation in mice: Participation of serotonergic but not
GABAA/ benzodiazepine neurotransmission. J Ethnopharmacol
2013;147(2):412418.
4. Omezu T. Evaluation of the effects of plant-derived essential oils on
central nervous system function using discrete shuttle-type conditioned
avoidance response in mice. Phytother Res 2012;26(6):884891.
5. Tisserand R. The art of aromatherapy. Essex. C.W. Daniel, 1977.
6. Sayorwan W, Siripornpanich V, Piriyapunyaporn T, Hongratanaworakit
T, Kotchabhakdi N, Ruangrungsi N. The effects of lavender oil inhalation
on emotional states, autonomic nervous system, and brain electrical
activity. J Med Assoc Thai 2012;95(4):598606.
7. Sayorwan W, Ruangrungsi N, Piriyapunyporn T, Hongratanaworakit T,
Kotchabhakdi N, Siripornpanich V. Effects of inhaled rosemary oil on
subjective feelings and activities of the nervous system. Sci Pharm
2013;81(2):531542.
8. Tildesley NT, Kennedy DO, Perry EK, Ballard CG, Wesnes KA, Scholey
AB. Positive modulation of mood and cognitive performance following
administration of acute doses of Salvia lavandulaefolia essential oil to
healthy young volunteers. Physiol Behav 2005;83(5): 699709.
9. Moss M, Cook J, Wesnes K, Duckett P. Aromas of rosemary and
lavender essential oils differentially affect cognition and mood in healthy
adults. Int J Neurosci 2003;113(1):1538.
10. Boukhatem MN, Ferhat MA, Kameli A, Saidi F, Kebir HT. Lemon grass
(Cymbopogon citratus) essential oil as a potent anti-inflammatory and
antifungal drugs. Libyan J Med 2014;9:25431.
11. Viana GS, Vale TG, Pinho RS, Matos FJ. Antinociceptive effect of the
essential oil from Cymbopogon citratus in mice. J Ethnopharmacol
2000;70(3):323327.
12. Cheel J, Theoduloz C, Rodriguez J, Schmeda-Hirschmann G. Free
radical scavengers and antioxidants from Lemongrass (Cymbopogon
citratus (DC) Stapf.). J Agric Food Chem 2005;53(7):25112517.
13. Costa CA, Kohn DO, de Lima VM, Gargano AC, Florio JC, Costa M.
The GABAergic system contributes to the anxiolytic-like effect of
essential oil from Cymbopogon Citratus (lemongrass). J Ethnopharmacol
2011;137(1):828836.
14. Blanco MM, Costa CA, Freire AO, Santos Jr JG, Costa M.
Neurobehavioral effect of essential oil of Cymbopogon citratus in mice.
Phytomedicine 2009;16(2-3):265270.
15. Goes TC, Ursulino FR, Almeida-Souza TH, Alves PB, Teixeira-Silva F.
Effect of lemongrass aroma on experimental anxiety in humans. J Altern
Complement Med 2015;21(12):766773.
16. Peth-Nui T, Wattanathorn J, Muchimapura S, et al. Effects of 12-week
Bacopa monnieri consumption on attention, cognitive processing,
working memory, and functions of both cholinergic and monoaminergic
systems in healthy elderly volunteers. Evid Based Complement Alternat
Med 2012, Article ID 606424.
17. Saenghong N, Wattanathorn J, Muchimapura S, et al. Zingiber officinale
improves cognitive function of the middle-aged healthy women. Evid
Based Complement Alternat Med 2012, Article ID 383062.
18. Barrett KE, Barman SM, Boitano S, Brooks HL. Smell and taste. In:
Barrett KE, Barman SM, Boitano S, Brooks HL (eds.). Ganong’s review
of medical physiology. 24th ed. New York. McGraw-Hill, 2012: pp. 217
226.
19. Buck LB. Smell and taste: The chemical senses. In: Kandel ER,
Schwartz JH, Jessell TM (eds.). Principles of neural science. 4th ed. New
York. McGraw-Hill, 2000: pp. 625647.
20. Herz RS, Eliassen J, Beland S, Souza T. Neuroimaging evidence for the
emotional potency of odor-evoked memory. Neuropsychologia
2004;42(3):371378.
21. D'Esposito M, Detre JA, Alsop DC, Shin RK, Atlas S, Grossman M. The
neural basis of the central executive system of working memory. Nature
1995;378(6554):279281.
22. Baddeley A. Working memory. Science 1992;255(5044):556559.
23. Goldman-Rakic PS, Muly, III EC, Williams GV. D(1) receptors in
prefrontal cells and circuits. Brain Res Rev 2000;31(23):295301.
24. Aalto S, Bruck A, Laine M, Nagren K, Rinne JO. Frontal and temporal
dopamine release during working memory and attention tasks in healthy
humans: A positron emission tomography study using the high-affinity
dopamine D2 receptor ligand [11C]FLB 457. J Neurosci 2005;
25(10):24712477.
25. Li BM, Mei ZT. Delayed-response deficit induced by local injection of the
2-adrenergic antagonist yohimbine into the dorsolateral prefrontal
cortex in young adult monkeys. Behav Neural Biol 1994; 62(2):134139.
26. Williams GV, Rao SG, Goldman-Rakic PS. The physiological role of 5-
HT2A receptors in working memory. J Neurosci 2002;22(7):28432854.
27. Granon S, Poucet B, Thinus-Blanc C, Changeux JP, Vidal C. Nicotinic
and muscarinic receptors in the rat prefrontal cortex: Differential roles in
working memory, response selection and effortful processing.
Psychopharmacology 1995;119(2):139144.
28. Oken BS, Salinsky MC, Elsas SM. Vigilance, alertness, or sustained
attention: physiological basis and measurement. Clin Neurophysiol
2006;117(9):18851901.
29. Wattanathorn J, Mator L, Muchimapura S, et al. Positive modulation of
cognition and mood in the healthy elderly volunteer following the
administration of Centella asiatica. J Ethnopharmacol 2008;116(2):325
332.
30. Ashby FG, Isen AM, Turken AU. A neuropsychological theory of positive
affect and its influence on cognition. Psychol Rev 1999; 106(3):529550.
31. Mitchell RL, Phillips LH. The psychological, neurochemical and
functional neuroanatomical mediators of the effects of positive and
negative mood on executive functions. Neuropsychologia 2007;45(4):
617629.
32. Elliott R, Zahn R, Deakin JF, Anderson IM. Affective cognition and its
disruption in mood disorders. Neuropsychopharmacology 2011;36(1):
153182.
33. Hongratanaworakit T. Physiological effects in aromatherapy.
Songklanakarin J Sci Technol 2004;26(3):117125.
32 88 Thai Pharm Health Sci J Vol. 1 No. , Apr. Jun. 2018
34. Heuberger E, Hongratanaworakit T, Bohm C, Weber R, Buchbauer G.
Effects of chiral fragrances on human autonomic nervous system
parameters and self-evaluation. Chem Senses 2001;26:281292.
35. Kamkaen N, Ruangrungsi N, Na Patalung N, Watthanachaiyingcharoen
R. Physiological and psychological effects of lemongrass and sweet
almond massage oil. J Health Res 2015;29(2): 8591.
36. Luine VN. Estradiol and cognitive function: Past, present and future.
Horm Behav 2014;66(4):602618.
37. Gur RC, Richard J, Hughett P, et al. A cognitive neuroscience-based
computerized battery for efficient measurement of individual differences:
standardization and initial construct validation. J Neurosci Methods
2010;187:254262.
38. Gur RC, Richard J, Calkins ME, et al. Age group and sex differences in
performance on a computerized neurocognitive battery in children age
8-21. Neuropsychology 2012;26(2):251265.
39. Murman DL. The impact of age on cognition. Semin Hear
2015;36(3):111121.
Editorial note
Manuscript received in original form on January 19, 2018;
accepted in final form on April 21, 2018
... These results are in line with the ones of another study in which cognitive and cardiovascular parameters were assessed in young, healthy female subjects before and after the inhalation of lemongrass essential oil for 5 min. Although subjects showed higher calmness and alertness scores when compared to a control group, no changes in blood pressure or heart rate were detected [109]. Recently, a patent for an aspersion system that creates an atmosphere of citral and linalool (10:1 ratio) to be inhaled with the intent of lowering blood pressure has been created [110]. ...
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Lemongrass (Cymbopogon citratus (DC) Stapf) is a herb commonly used in folk medicine for many purposes. However, its anti-hypertensive potential has not yet been thoroughly studied. This paper reviews the anti-hypertensive effects of both lemongrass and its main compound citral in in vitro, ex vivo, preclinical and clinical studies. Lemongrass essential oil contains terpenes and their derivatives, whereas extracts contain different classes of polyphenols. Both citral and lemongrass display vasorelaxant activity ex vivo, acting by the promotion of endothelial nitric oxide/prostanoids secretion together with the blockage of calcium channels in the vascular smooth muscle. Citral also displays a negative chronotrope effect, probably due to a centrally mediated enhancement of parasympathetic activity. In both healthy and hypertensive animals, the acute administration of lemongrass results in a decrease in blood pressure, sometimes accompanied by a compensatory increase in heart rate. Similarly, in healthy and hypertensive human subjects, the consumption of lemongrass tea decreases blood pressure. Additionally, a weak/moderate diuretic activity has also been reported in animals and humans, although the mechanisms of action remain elusive. Future preclinical studies are necessary to identify other compounds with anti-hypertensive activity and additional pharmacological pathways. Although well tolerated, the safety profile of lemongrass should be better characterized.
... The C. citratus essential oil inhalation could improve the cognitive function and modulate mood of healthy women with no effect on the physiological status. However, the underlying mechanisms of these positive effects still require further studies (Sriraksa et al., 2018). ...
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The genus Cymbopogon (Greek words 'kymbe' meaning boat and 'pogon' meaning beard), commonly known as lemongrass, belongs to the Poaceae family. It comprises a large number species, but only two have economic importance as cultivated plants: C. citratus and C. flexuosus. However, C. citratus is more resistant to drought and low temperatures and because of that can be cultivated over large areas therefore it is commercially more important. C. citratus leaves are widely used as a lemon flavor ingredient in herbal teas, prepared either by decoction or infusion, or in finished herbal products such as capsules, tablets and creams. Even though essential oils are known for being used for fragrance and as an important ingredient in Asian cuisine, they are also used in other industries (pharmaceutical and cosmetic) due to their bioactive compounds that show various therapeutic effects. The chemical composition of C. citratus essential oil varies widely depending on genetic diversity, habitat and agronomic treatment of the culture, as well as on the part of the plant, maturity stage and extraction method. However, the essential oil of C. citratus mainly consists of the citral, which is a mixture of two isomeric acyclic monoterpene aldehides: geranial (trans-citral) and neral (cis-citral). C. citratus possesses good antibacterial activity, it could be used as alternative treatment for enteric fever, to cure infectious diseases related to the respiratory system, as well as for oral hygiene, it helps by removing bacteria from the oral cavity and prevents teeth and gum diseases such as peridontitis, plaque and gingivitis. Furthermore, C. citratus showed high contents of total phenolic and total flavonoids, as well as high free radical scavenging capacity with potential as an antioxidant. C. citratus shows good antiinflamatory, anti-diabetic, hypolipidemic, renoprotective and cardioprotective, as well as anticancer activities. Apart from this, C. citratus possesses vasorelaxant, sedative and antitusive potential. Furthermore, the compound citral is used in perfume industry as well as for cleaning wounds and treatment of skin diseases in forms of gels, or functional paper microencapsulated with essential oil, which can be used for hand hygiene.
... Each item was classified into three factor scores including alertness, calmness, and contentment. 17 Salivary cortisol collection and measurement. At around 5 PM, saliva samples of participants were collected into salivette cotton tubes. ...
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Chapter
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