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Indian J Physiol Pharmacol 2015; 59(1)
Ocimum Sanctum
and Cognitive Performance 69
Original Article
Holy basil (Ocimum sanctum Linn.) leaf extract enhances specific
cognitive parameters in healthy adult volunteers: A placebo
controlled study
Suneetha Sampath1, S.C. Mahapatra1, M.M. Padhi2, Ratna Sharma1
and Anjana Talwar*1
1Department of Physiology,
All India Institute of Medical Sciences,
New Delhi, India
2Central Council for Research in Ayurveda and Siddha,
Department of Ayurveda, Yoga and Naturopathy, Unani and Siddha (AYUSH),
New Delhi, India
Abstract
Introduction:
Ocimum sanctum
(OS), known as Holy basil, has been documented to possess neuro-
protective, cognition-enhancing and stress relieving effects in animal models. However there is paucity of
clinical studies to document these effects.
Materials and methods: Effect of OS on parameters related to cognition and stress in humans was
evaluated with administration of 300 milligram capsules of ethanolic leaf extracts of
Ocimum sanctum
(EtOS)
or placebo per day, over 30 days.
Results: Intra-group comparison of Sternberg and Stroop test showed improvement in both the placebo and
EtOS groups, however, the improvement stabilized after day 15 in the placebo group. Intergroup comparison
revealed a significant improvement of the following cognitive parameters in the EtOS as compared to the
placebo: reaction time (RT) and error rate (ER) of Sternberg test, RT of neutral task of Stroop, RT and ER
of interference task of Stroop.
The intra-group comparison of P300 latency, salivary cortisol, and State-Trait Anxiety Inventory showed
improvement over time in the EtOS group alone, though the inter-group difference was significant in the P300
latency alone. There were no changes in heart rate (HR), ΔHR, or galvanic skin response (GSR) or ΔGSR.
Conclusion:
Ocimum sanctum
leaf extract seems to have potential cognition-enhancing properties in humans.
Indian J Physiol Pharmacol 2015; 59(1) : 69–77
*Corresponding author :
Dr. Anjana Talwar, Dept of Physiology, All India Institute
of Medical Sciences, New Delhi, India
Email: anjanatalwar@gmail.com
(Received on September 10, 2014)
Introduction
Ocimum tenuiflorum, also known as
Ocimum sanctum
(OS) (Holy Basil) is an aromatic plant in the family
Lamiaceae, native to south-east Asia and the tropics.
It is referred to as ‘Tulsi’ in India, and has been
used extensively in ayurveda, the traditional Indian
system of medicine. Extracts of the leaves of OS
are known for its calming and relaxing effects.
Alcoholic extract of leaves of OS contain ursolic acid,
apigenin, luteolin, apigenin-7-O-glucuronide, luteolin-
70 Sampath, Mahapatra, Padhi, Sharma and Talwar Indian J Physiol Pharmacol 2015; 59(1)
the chronic stress-induced neurochemical
perturbations in rats. There was a normalization of
the concentrations of Noradrenaline (NA) and
dopamine (DA) in frontal cortex, pons-medulla,
hypothalamus hippocampus and that of 5-
hydroxytryptamine (5HT) in frontal cortex, pons
medulla, hypothalamus and hippocampus, induced
by electroshock stress (16). Administration of 70%
EtOS also provided similar results, normalizing the
neurotransmitter levels in discrete brain areas induced
by noise stress (17, 18).
EtOS normalized the reduction in total acetylcholine
content and the increase in the activity of
acetylcholinesterase in cerebral cortex, corpus
striatum, hypothalamus and hippocampus of rat brain
(19, 4). EtOS also attenuated the lipid peroxidation
by normalizing the levels of superoxide dismutase ,
catalase, glutathione peroxidase and glutathione, in
a dose-dependent manner (15). EtOS also possessed
strong free radical scavenging action and provided
increased resistance against thermal stress in C.
elegans
which has been postulated due to modulation
of some signaling pathways (20).
Despite availability of extensive pre-clinical evidences
on anti-stress activity of OS, only two clinical reports
have documented beneficial effects of OS in
questionnaire based study. OS extract 500mg twice
a day, taken over 60 days, significantly attenuated
stress and depression levels in 35 patients with
generalized anxiety disorder (16). Intake of OciBest®,
a commercial preparation of OS, at dose of 1200
mg/day over 6 weeks, resulted in symptomatic
improvement based on a self-reported questionnaire
in 71 patients having symptoms of stress (21). Dose
of
Ocimum Sanctum
used in these studies was higher
in comparison to the dose used (300 mg/day) for
eliciting the Immuno-modulatory effects of EtOS in
healthy subjects in our laboratory (22). In these
subjects there was an increase in the levels of
IFN-γ, IL-4 and percentages of T-helper cells and
NK-cells after 4 weeks of intake of EtOS. Thus, in
the present study also, EtOS was used in the dose
of 300 mg/day for thirty days.
The study was designed to investigate the cognition
enhancing and anti-stress potential of ethanolic leaf
7-O-glucuronide, isorientin, orientin, molludistin,
stigmasterol, vicenin-2, vitexin, isovitexin, aesculetin,
aesculin, chlorgenic acid, galuteolin, circineol, gallic
acid, procatechuic acid, vallinin acid, chlorogenic
acid, β stigmasterol (1).
Preliminary evaluation of the psychopharmacological
effects of EtOS showed that it had anti-convulsant,
anti-anxiety and anti-depressant effects (2).
Administration of Ethanolic extract of OS (EtOS) had
a favorable effect on cognitive parameters in animal
models. EtOS ameliorated the amnesic effects in
cognitive dysfunction in rat model (3, 4) and improved
learning and memory in alzheimer’s rat model (5).
EtOS also had beneficial effects in cerebral
reperfusion injury and cerebro-vascular insufficiency
states (6, 7).
Treatment with EtOS normalized the alterations in
various parameters like plasma corticosterone (8),
WBC count and neutrophil function (9) induced by
acute and chronic noise stress, in albino rats. High
doses of EtOS also had a nervous system stimulant
and/or antistress effects comparable to that of
desipramine, as assessed by mouse swimming
performance test (10). OS containing formulations
(EuMil) attenuated chronic stress induced alterations
in glucose intolerance, suppression of male sexual
behavior, and cognitive dysfunction in albino rats, in
a dose dependent manner, comparable to that of
Ginseng (11). Aqueous extracts of OS and C.
sinensis reduced the behavioral alterations induced
by restraint stress in rats (12). EtOS showed anti-
anxiety and anti-depressant effects, as evaluated by
various behavioral experiments (13).
The psychopharmacological effects of OS have been
postulated to involve dopaminergic neurons as the
effects were blocked by haloperidol, and synergized
by bromocriptine (2). Ocimumosides A, Band 4-allyl-
1-O-beta-D-glucopyronosyl-2-hydroxybenzene have
been postulated for the the anti-stress properties of
OS (14). The abundance of phenolics and flavanoids
have been held responsible for the anti-oxidant effect
of EtOS (15).
Formulations containing extracts of OS, ameliorated
Indian J Physiol Pharmacol 2015; 59(1)
Ocimum Sanctum
and Cognitive Performance 71
extract of
Ocimum Sanctum.
Participants and methods
Study design
The study was performed in a double-blinded
randomized control manner after obtaining ethical
clearance from institutional ethics committee and
registered with clinical trial registry of India (CTRI)
CTRI/2010/091/006113. The study was conducted at
the Deptt. of Physiology, AIIMS, New Delhi.
Subjects
44 apparently healthy male subjects, aged 18-30
years, were recruited on voluntary basis. Subjects
suffering from long term diseases/disabilities, chronic
smokers and those on any long term medication
were excluded from the study based on a clinical
interview. Subjects were asked to abstain from
smoking, alcohol and caffeine containing beverages
on the day of the experimental session.
On the day before the first recording session,
subjects were briefed about the study, familiarized
with the recording procedures. A written informed
consent was obtained and subjects were asked to
pick up a lottery and randomly allocated into either
group A or B. Recordings were done on day 0 (D0),
day 15 (D15) and day 30 (D30). 23 subjects were
recruited in group A and 21 in group B.
Interventional drug (
Ocimum sanctum
extract/placebo):
70% ethanolic extract of
Ocimum sanctum
(EtOS),
prepared from dried leaves, was supplied by central
council for research in ayurveda and siddha (CCRAS),
India for which the leaves of
Ocimum sanctum L.
were procured from Dindigal area of Tamil Nadu,
South India in October 2006 and its authenticity and
the identity was established by careful scrutiny of
taxonomical features after the consultation of
literature
Flora of Presidency of Madras.
Vol. 2 Adlard
& Sons Ltd. and Database on Medicinal Plants used
in Ayurveda, Vol.2 by CCRAS, New Delhi, and after
matching with the raw material specimen R.D. no
792 in Raw Drug Museum of CCRAS identified as
Ocimum sanctum
L. leaf, it was deposited in raw
drug museum of CCRAS under the raw drug serial
No 6001 for further reference.
Quality assessment run for EtOS was done by Quality
Control Laboratory, M/s. chemiloids, Laila Impex,
Vijayawada, India lab reference no.L 7040426, for
solvent residues, heavy metals, pesticide residues,
microbiological contamination and phyto-chemical
specifications (ursolic acid >2.7% w/w). Placebo
(sucrose) was supplied by the Dabur Pharmaceutical
(India) Ltd., Ghaziabad (U.P.), India. Capsules of
300 milligram of either the drug or placebo (sucrose)
were identically capsulated and could not be
distinguished from each other. 30 capsules of EtOS
or placebo were packaged in identical air-sealed
bottles and labelled A or B, by the GLP certified
laboratory of Dabur research foundation, India. The
packed containers were dispatched from laboratory
of Dabur research foundation, India to the study site.
The subject and the experimenter were blinded to
the identity of capsules in the bottles.
Immuno-modulatory effects of EtOS in healthy
subjects have been documented using the same
capsules at the same dose (300 mg/day), in our lab,
and no adverse effects were reported (22). Subjects
in group A and B took one capsule a day from bottle
A or B respectively, each morning, on empty
stomach. They were instructed to record and report
any health related symptom during this period, in
the absence of which, they reported back for the
assessment and recording on D15 and D30.
Assessment of cognitive function:
Sternberg and Stroop task were administered through
computerized Psych/LabTM Software (Richard A
Abrahams, Department of Psychology, Washington,
University of Missouri, USA). Event related potential
(ERP) was assessed using RMS EMG EP-Mark II
system, Recorders and Medicare Systems Pvt Ltd,
Chandigarh, India.
Sternberg memory task tests the accuracy and speed
of short term memory load. The program ‘MEMSCAN’
runs a version of the Sternberg memory scanning
paradigm. There were 3 blocks containing 12 trials
72 Sampath, Mahapatra, Padhi, Sharma and Talwar Indian J Physiol Pharmacol 2015; 59(1)
each (1st block not taken for analysis). On each
trial, a set of to-be-remembered digits was first
presented. The size of the set varies on each trials
from 1 to 6. The memory set is then replaced by a
plus sign and, after a short delay, a probe digit. The
subject’s task is to respond as quickly as possible
by pushing the forward slash key if the probe was a
member of the set, or the Z key if the probe was not
a member of the memory set. The reaction time (RT)
and error rate (ER) were measured (23).
The Stroop test measures cognitive flexibility. The
program ‘STROOP’ runs a version of the Stroop
paradigm. The Stroop test measures the ease with
which a subject can shift his perception to conform
to changing demands and inhibit attention to
competing stimuli. The subject has to respond to
the color in which the word is printed by pressing
the appropriate key as quickly as possible. Three
different paradigms of facilitation, neutral and
interference tasks were administered in separate
blocks, each with 24 trials. In neutral task the letter
string is composed of Xs. In interference task the
letter string is one of the words red, green, blue, or
yellow printed in a color different from the named
color. In facilitation task the letter string is the name
of the color that the letters are printed in. On each
trial, the subjects were presented with a string of
letters printed in color; and they were instructed to
respond to the colour in which the word was printed,
by pressing the appropriate colored key of the
keyboard as quickly as possible (24).
Auditory event-related potentials were elicited using
auditory oddball paradigm, with amplitude, 50-60 dB
greater than the auditory threshold of the subject.
The standard (1000 Hz) and the target tone (2000
Hz) were in the frequency of 4:1 and the results of
36 rare stimuli were averaged.
The event related potential was recorded using the
EEG activity (filter bandpass:0.1-50Hz, analysis
time:1sec) recorded at Cz and Pz sites according to
the 10/20 system. The resistance was kept below 5
kohm. The latency and amplitude of P300 was
measured (25).
Assessment of stress parameters:
Saliva was collected on the recording day, at the
beginning of tests and stored at –70°C. Cortisol levels
were estimated by ELISA kits.
The mental and emotional acute stress was
assessed using Spielberger state and trait anxiety
inventory (STAI), a self reported assessment device,
administered before the testing for cognitive
parameters. The maximum and minimum achievable
scores of the STAI are 20 and 80 respectively (26).
The Lead II of ECG was recorded continuously for
measuring the changes in heart rate. The galvanic
skin response (GSR) or conductivity of the skin was
recorded with RMS POLYRITE-D systems. Two Ag/
AgCl electrodes around the index and middle finger
of the participant’s left hand were tied to record the
GSR, which is a relatively reliable index of sweat-
gland activity and changes in the activation level of
the sympathetic nervous system.
60-300 seconds of artifact free data of HR and GSR
were used to calculate the mean value, for purpose
of comparison between basal and different cognitive
tasks. The results of baseline GSR and HR were
recorded at the start of the testing procedures on
each testing day. ΔGSR and ΔHR were measured
as the difference between maximum recorded GSR
or HR during performance of various tasks and the
baseline GSR or HR recorded during that day.
Statistical analysis
Statistical analysis was made using Graphpad Prism
5. All the variables were found to be normally
distributed as assessed by D’ Agostino and Pearson
omnibus normality test. Intra-group comparison was
made by Repeated measures ANOVA with Bonferroni
post-hoc multiple comparison test and inter-group
comparison was made with two tailed, unpaired t-
test. P<0.05 was considered significant. After the
analysis, the blinding was opened and it was revealed
that Group A and B were placebo and EtOS
respectively.
Indian J Physiol Pharmacol 2015; 59(1)
Ocimum Sanctum
and Cognitive Performance 73
in the groups were not significantly different in
their educational qualification, age, height, weight or
BMI.
Sternberg memory test:
The reaction time (RT) and error rate (ER) of the
Sternberg memory scan test are presented in Table
II and III respectively.
There was an improvement in the RT of the
Sternberg, in both groups, over time. Though the
initial improvement at D15 was comparable at 4.3%
and 4.9%, the improvement was very marginal
between D15 and D30 in the Placebo group (1.3%),
as compared to EtOS group (4.3%). The inter-group
comparison in RT at D30 was significant.
There was a reduction in the ER of the Sternberg, in
both groups, over time. The % change in ER, between
D0 and D30, in placebo and EtOS groups was 38
Results
Demographic data and compliance:
A total of 44 subjects were inducted for the study.
The disposition of subjects is represented in Table
I. Compliance in taking the capsules each day was
greater than 90%. Two subjects in group A and one
in group B were lost to follow-up due to work- time
restriction and one subject in group A discontinued
the medication complaining of nausea. The subjects
TABLE I : Comparison of physical characteristics at baseline.
Placebo (n=20) EtOS (n=20) P value
Age (years) 27.53±2.64 27±2.82 NS
Height (cm) 170.26±7.38 170.5±3.3 NS
Weight (kg) 67.33±5.75 65.37±3.05 NS
BMI (kg/m2) 23.24±1.71 22.5±1.22 NS
Values are expressed as Mean±SEM. Unpaired t test
between Placebo and EtOS groups.
TABLE II : Effects of
Et
OS (n=20) and placebo (n=20) on Reaction time (msec) of Sternberg memory scan test and Stroop test.
Test Group Day 0 Day 15 Day 30 P value
Sternberg test Placebo 931.9±21.58 891.4±23.28 879.7±23.47 <0.001
P<0.01aP<0.001b
NSc
EtOS 892.1±18.99 847.7±2.36 810.6±23.83 <0.001
P<0.001aP<0.001b
P<0.01c
P value NS NS <0.05
Facilitation task Placebo 796.6±21.27 791.5±16.54 767.1±16.59 NS
NSaNSbNSc
EtOS 805.5±25.78 756.3±26.53 725.3±21.80 <0.01
NSaP<0.01b
NSc
P value NS NS NS
Neutral task Placebo 832.1±13.50 809.7±15.22 800.8±18.74 <0.05
NSaP<0.05b
NSc
EtOS 827.7±27.04 794.8±22.05 734.9±19.71 <0.001
NSaP<0.001b
P<0.01c
P value NS NS <0.05
Interference task Placebo 930.6±17.11 903.9±17.00 894.9±17.02 <0.05
NSaP<0.05b
NSc
EtOS 949.9±21.76 895.0±22.69 839.7±20.75 <0.001
P<0.01aP<0.001b
P<0.01c
P value NS NS <0.05
Values are expressed as Mean±SEM. NS: not statistically significant, RM: Repeated measures ANOVA with Bonferroni post-
hoc multiple comparison test for intragroup comparison.Unpaired t test between Placebo and EtOS groups. a
Comparison of
day 0 and day 15. bComparison of day 0 and day 30. cComparison of day 15 and day 30.
74 Sampath, Mahapatra, Padhi, Sharma and Talwar Indian J Physiol Pharmacol 2015; 59(1)
and 66 respectively. The inter-group comparison in
ER at D30 was significant
Stroop test:
The RT and ER of Stroop task are tabulated in Tables
II and III respectively.
Facilitation task:
Though there was an improvement in the RT of
Facilitation task in the EtOS group only, ER reduced
in both the placebo and EtOS groups. The inter-
group comparisons of RT and ER at D15 or D30
were not significant.
Neutral task:
There was an improvement in the RT of Neutral task
in both the placebo and EtOS groups over time. At
D30, the percentage change in RT, as compared to
D0, in the placebo and EtOS groups was 3.7 and
11.2 respectively. Interestingly, as in the Sternberg
test, the improvement was minimal between D15 and
D30 in the placebo group (1.1%) as compared to the
EtOS group (7.5%). The inter-group comparison in
RT at D30 was significant.
The inter and intra-group comparisons of ER of Neutral
task at D15 or D30 were not significant (data not
given).
Interference task:
There was an improvement in the RT of interference
task, in both the Placebo and EtOS groups. The
percentage change in RT between D0 and D30 were
3.8 and 11.6 in the placebo and EtOS groups
respectively. Similar to the Sternberg test and neutral
task of Stroop test, there was only a minimal
improvement between D15 and D30 in the placebo
group (0.9%) as compared to the EtOS group (6.1%).
The inter-group comparison in RT at D30 was
significant.
Though there was a significant reduction in the ER
TABLE III : Effects of EtOS (n=20) and placebo (n=20) on Error rate (percentage) of Sternberg memory scan test and Stroop test.
Test Group Day 0 Day 15 Day 30 P value
Sternbergtest Placebo 5.30 4.00 3.30 <0.001
(4.00–8.30) (3.00–6.80) (1.92–5.18)
P<0.05aP<0.001b
P<0.05c
EtOS 4.68 3.67 1.60 < 0.001
(4.05–8.30) (2.00–6.10) (0.00–3.80)
P<0.05aP<0.001b
P<0.01c
P value NS NS <0.05
Facilitation task Placebo 1.00 1.30 0.00 <0.05
(0.00–2.75) (0.00–1.39) (0.00-1.00)
NSaNSb NSc
EtOS 0.05 1.30 0.00 <0.01
(0.00–2.68) (0.00–1.39) (0.00-1.00)
NSaNSb NSc
P value NS NS NS
Interference task Placebo 2.89 2.08 1.89 <0.05
(1.39–5.5) (1.40–4.17) (1.39-2.78)
NSa NSaNSb NSc
EtOS 4.05 2.78 1.34 <0.001
(1.25–5.89) (0.25–4.17) (0.10-2.78)
NSa<0.001b
NSc
P value NS NS <0.05
Values are expressed as Median (Interquartile range). NS: not statistically significantFriedman test with Dunn’s multiple
comparison for intragroup comparison.Mann-Whitney U test between Placebo and EtOS groups. a
Comparison of day 0 and
day 15. bComparison of day 0 and day 30. cComparison of day 15 and day 30.
Indian J Physiol Pharmacol 2015; 59(1)
Ocimum Sanctum
and Cognitive Performance 75
of interference task in both the groups, the
percentage change in ER, between D0 and D30, were
35 and 66 in the placebo and EtOS groups
respectively. The inter-group comparison in ER at
D30 was significant.
Event related potential:
P300 latency was comparable at D0 in the placebo
(286.7±18.23 ms) and EtOS groups (284.5±21.86 ms).
There was a significant reduction of the P300 latency
in the EtOS group alone to 270.9±21.78 ms on D30
(p<0.01). This comparison was significant between
D15-30 (p<0.05) and D0-30 (p<0.001). The inter-group
comparison of P300 at D30 was significant (p=<0.05).
The P300 amplitude was not significantly different in
two groups at any point of time (Data not included).
Salivary cortisol:
The baseline salivary cortisol levels were comparable
at 7.15±3.27 and 7.16±3.60 nmol/L in the placebo
and EtOS groups respectively. There was a significant
(p<0.001) reduction in the salivary cortisol values in
the EtOS group alone (14%) This reduction was
significant only after D15. The inter-group
comparisons at D15 or D30 were not significant.
State and Trait Anxiety Inventory (STAI):
The scores of State component of STAI were
comparable at D0 in the placebo (32.70±7.93) and
EtOS groups (34.30±7.01), (p>0.05). There was a
significant reduction in the scores in the EtOS group
alone to 29.45±6.17 (p<0.001). This comparison was
significant only between D0-D30 (p<0.001). The
inter-group comparison was not significant at D15 or
D30.
The scores of Trait component of STAI were
comparable in the placebo (34.85±4.17) and EtOS
groups (36.80±5.54) (p=NS). There was a significant
reduction in the scores in the EtOS group alone
to 32.95±4.51 (p<0.001). This comparison was
significant between D15-30 (p<0.05) and D0-30
(p<0.001).
GSR and HR:
The baseline GSR and HR at D0 in the placebo and
EtOS groups were comparable at 9.30±1.30 µS,
69.70±10.15 per min and 9.11±1.14 µS, 70.65±8.71
per min respectively. The ΔGSR and ΔHR at D0 in
the placebo and EtOS groups were 0.75±0.52 µS,
29.55±8.51 per min and 0.79±0.55 µS, 27.75±10.83
per min respectively. There were no significant inter-
group or intra-group differences in any of these
parameters on D15 or D30.
Discussion
The effects of EtOS on stress and cognition
were studied on 40 healthy human volunteers by a
double-blinded randomized control study over 30
days.
Results of the study showed that both placebo and
EtOS intake over a period of 30 days resulted in a
significant improvement in the RT of Sternberg test,
neutral and interference task of Stroop test. The ER
of Sternberg test, facilitation and interference task
of Stroop test also showed improvement in both the
groups. ‘Practice effect’ is a well known phenomenon
wherein familiarization and repeated testing of the
same cognitive parameter in a sub-group increased
responsiveness and performance (27, 28). It is worth
noting that the improvement in the placebo group
tended to plateau after D15, while in the EtOS group
there was a continued significant improvement beyond
the D15. Also, inter-group comparison of RT and ER
of Sternberg and Interference task, and RT of Neutral
task in the EtOS group, showed that EtOS had a
beneficial effect over and above the Placebo.
Sternberg test, a parameter to assess short term
memory and central executive functions of cognition,
represents information processing and retrieval of
information (23). Stroop task is a parameter of
cognitive flexibility, represents goal-directed working
memory (24). The extract of
Ocimum sanctum
seems to have the potential to improve short term
memory and cognitive flexibility. This is the first study
to document the enhancement of cognitive
performance of the subjects after intake of OS for a
short period.
76 Sampath, Mahapatra, Padhi, Sharma and Talwar Indian J Physiol Pharmacol 2015; 59(1)
In animal models of Alzheimer’s disease, extract of
OS has been shown to improve learning and memory
deficits, improve spatial learning and alleviate the
associated neuropsychological symptoms. The
beneficial effect observed with OS have been
attributed to its anti-oxidant activity in animal studies
(5). The active principle of the ethanolic leaf extract
of OS used in this study contains 2.7% ursolic acid,
a compound, which has antioxidant properties and
gives remarkable protection against lipid peroxidation
(29, 30).
The P300 latency, an indicator of memory capacity
and attention (31), remained fairly constant in the
placebo group. However the significant improvement
in the EtOS group, beyond D15, indicates that EtOS
had a favorable effect on attention.
In the placebo group, though there was an
improvement of the RT, P300 latency remained fairly
constant. However EtOS showed improvement in both
RT and P300. P300 reflects relative timing of
stimulus evaluation whereas RT reflects relative timing
of response processes (32). The differential response
of OS to RT and P300 could provide a lead point to
probe into the key neuronal processes through which
OS may act.
Our study group predominantly contained
academically successful young adults, who had good
cognitive capacity. It is interesting to note that
administration of EtOS could improve the cognitive
parameters of those even in this population.
Salivary cortisol levels significantly decreased in the
EtOS group alone. But the lack of inter-group
differences and the magnitude of change, indicate
that this may not be clinically significant. Cortisol is
a hormone whose concentrations are extremely
variable and subjected to important circadian
variation. One single measurement in a day is not
significant, as it could be altered by an extremely
high number of variables. Measurement of cortisol
awakening response or repeated measurements of
salivary cortisol levels could have thrown better light
and we consider it a limitation of the study with
respect to this parameter.
The scores of state and trait components of STAI
were significantly decreased in the EtOS group alone,
but there were no differences on inter-group
comparison. The healthy young individuals included
in the study seemed to have low-normal baseline
score of STAI indicating there did not suffer from a
lot of anxiety. Inclusion of aged volunteers who may
suffer from stress may be useful to understand the
real time significance. There were no significant
differences in basal or ΔHR and GSR responses
between the groups. Thus the effects
Ocimum
sanctum
of on stress could not be established in
the population with the current dose and parameters
used.
A reduction in stress in 71 subjects having symptoms
of stress (21) and reduction in anxiety and depression
in patients of generalized anxiety disorder (16) has
been documented earlier based on self reported
questionnaires with a higher dose for longer period.
Estimation of cortisol was not done in these studies
though the authors stated that major action of
Ocimum Sanctum
in stress related disorder is via
modulation of hypothalamus-pituitary-adrenocortical
axis. Thus, there are no objective studies available
to assess the cognitive enhancement and anti- stress
effect of OS in humans.
Thus,
Ocimum sanctum
does seem to have a
favorable effect on certain cognitive parameters
like short term memory, cognitive flexibility and
attention. Clinical significance of these effects
could be verified by conducting the study with a
larger population in vulnerable age group and by
increasing the dose and duration of intake of
Ocimum
Sanctum
.
Conflict of Interest:
No conflict to disclose
Acknowledgements
Authors are thankful for the Financial Support received
from institute research grant, AIIMS, New Delhi.
Indian J Physiol Pharmacol 2015; 59(1)
Ocimum Sanctum
and Cognitive Performance 77
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