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蝶豆根改善链脲霉素诱导的糖尿病模型大鼠认知减退(英文)



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DOI:10.3736/jcim20120816
http://www.jcimjournal.com
Talpate KA,Bhosale UA,Zambare MR.Clitorea
ternatea,a herb from Indian folklore,improves
streptozotocin-induced diabetes and diabetes-induced
cognitive decline in rats.J Chin Integr Med.2012;
10(8):939-947.
Talpate KA,Bhosale UA,Zambare MR.蝶豆根改善
链脲霉素诱导的糖尿病模型大鼠认知减退.中西医结
合学报.2012;10(8):939-947.
Received February 8,2012;accepted February 27,
2012;published online August 15,2012.
Ful-text LinkOut at PubMed.Journal title in PubMed:
Zhong Xi Yi Jie He Xue Bao.
Correspondence:Uma A.Bhosale,MD,Associate Pro-
fessor;Tel:+91-92-26767554;E-mail:umabhosale2000
@gmail.com
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ISSN 1672-1977.Published by JCIM Press,Shanghai,China.
Original Experimental Research 实验论著 
Clitorea ternatea,a herb from Indian folklore,improves
streptozotocin-induced diabetes and diabetes-induced
cognitive decline in rats
Karuna A.Talpate1,Uma A.Bhosale2,Mandar R.Zambare1
1.Department of Pharmacology,Sinhgad Colege of Pharmacy,Vadgaon,Pune 411041,Maharashtra,India
2.Department of Pharmacology,Smt.Kashibai Navale Medical Colege and General Hospital,Narhe,Pune
411041,Maharashtra,India
OBJECTIVE:To study the antidiabetic,neurochemical-antioxidant and cognition protective
efects of Clitorea ternatealeaves on a rat model of diabetic cognitive decline.
METHODS:Antidiabetic activity was evaluated by serum glucose and body weight estimation
in ethanol extract of Clitorea ternatea(EECT)-treated diabetic rats.Efects of EECT on spatial
working memory(SWM)and spatial reference memory(SRM)were evaluated by Y-maze and
Morris water maze tests respectively.Neurochemical-antioxidant efects of EECT were studied
by acetylcholinesterase assay,and measurements of thiobarbituric acid reactive substances
(TBARSs),superoxide dismutase(SOD)and catalase(CAT)levels in diabetic rats.
RESULTS:The 200 and 400 mg/kg of EECT showed a significant antidiabetic activity by
decreasing serum glucose level(P<0.05,P<0.01),and there was a significant increase in
the body weight in 400 mg/kg of EECT-treated diabetic rats(P<0.01).EECT was found to
cause significant increases in SWM and SRM in retention trials on Y-maze and Morris water
maze respectively(P<0.05,P<0.01).Significant decreases in acetylcholinesterase activity
and TBARS level,and significant increase in CAT level were observed in rats treated with 200
and 400 mg/kg of EECT compared with rats in the diabetic control group(P<0.05 or P<
0.01).Significant increase was also found in SOD in rats treated with 400 mg/kg of EECT.
CONCLUSION:Clitorea ternatea exhibits antidiabetic and antioxidant activities,ofers the
protection against diabetes-induced cognitive decline,and warrants the need for further studies
to elucidate its mode of action.
KEYWORDS:diabetes melitus;hypoglycemic agents;plants,medicinal;neurobehavioral
manifestations;rats,Sprague-Dawley
·939·中西医结合学报2012年8月第10卷第8期 Journal of Chinese Integrative Medicine,August 2012,Vol.10,No.8
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 Diabetes melitus(DM)is a devastating disease
throughout the world.Cognitive dysfunction,
Alzheimers disease and dementia are some of
wel recognized complications of DM though less
addressed[1-3].Cognitive dysfunction itself represents
a serious problem and is rising in prevalence
worldwide,especialy among the elderly diabetics.
Hyperglycemia,oxidative stress and cholinergic
decline play apivotal role in cognitive impairment
in diabetic encephalopathy[4,5].Antidiabetic and
psychotropic drugs are associated with several
adverse effects,hence in recent years,there has
been a gradual revival of interest concerning the
use of medicinal plants worldwide,even their
biologicaly active compounds are unknown,because
plant-derived drugs have been reported to be safe
and without side effects[6,7].
 Hyperglycemia produces reactive oxygen species
(ROS)as a result of glucose auto-oxidation,metabolism
and the development of advanced glycosylation
end products.In fact,diabetes is typicaly associated
with increased generation of free radicals and impaired
antioxidant defense qualifications,representing a
central contribution for ROS in the onset,progression,
and pathological consequences of DM,namely,
vascular complications,nephropathy and cognitive
impairment or dementia[8,9].This oxidative stress
became evident by increased lipid peroxide and
decreased superoxide dismutase(SOD)and catalase
(CAT)levels[10].
 Neurotransmitter functions which are altered in
DM include decreased acetylcholine production,
serotonin turnover and dopamine activity,and
increased norepinephrine[11].Considerable exper-
imental evidence exists for a relation between the
decline in cholinergic functions and dementia[5].
 In Ayurveda,the roots,seeds and leaves of
Clitorea ternatea have been widely used as a brain
tonic and are believed to promote memory and
inteligence[12].C.ternateais reported to have anti-
depressant,anticonvulsant[13],anti-inflammatory,
analgesic,antipyretic[14],local anesthetic[15],purga-
tive[16]and antidiabetic[17]activities.It is also used for
snakebite and scorpion sting in India
[18].The current
study was designed to explore the antidiabetic,
neurochemical-antioxidant and cognition protective
activities of ethanol extract of Clitorea ternatea
(EECT)leaves in an experimental rat model for
DM-induced cognitive decline.This study may be
a holistic approach towards developing a novel
drug from Indian folklore for diabetic dementia.
1 Materials and methods
1.1 Plant materials The leaves of Clitoreaternatea
were colected in November 2009 from the local
areas of Pune,Maharashtra,India.The plant
material was authenticated at Botanical Survey of
India,Pune,and the voucher specimen BB680518
was deposited.The leaves were dried under shade
and later pulverized in a mechanical grinder.The
100 g of powder was then extracted with 95%
ethanol for one week.The mixture was then filtered
and the filtrate was concentrated under reduced
pressure to yield semisolid 3.70% (weight ratio)
extract.The extract was preserved in a refrigerator
til further use.
1.2 Selection and maintenance of animals Adult
Sprague-Dawley rats of either sex,weighing between
150 to 250 g were used for the study.The animals
were housed in standard polypropylene cages at
room temperature and provided with standard
diet and water ad libitum.The experimental
protocol has been approved by the Institutional
Animal Ethics Committee(SCOP/IAEC/Approval/
2009-10/10).The animals were shifted to the
laboratory 1 h prior to the experiment.
1.3 Drugs and chemicals Metformin was obtained
from the Cipla Pharmaceuticals Ltd,India.Piracetam
(Nootropil,80 mg tablet);streptozotocin(Sigma
Aldrich,USA);diagnostic kits (Biolab,India)
for detecting malondialdehyde(MDA),SOD,CAT
(Sigma Aldrich,USA)were purchased from local
market.Other chemicals used were of analytical
grade and obtained from Qualigens,India.
1.4 Phytochemical study Clitorea ternatea was
evaporated to residue and diluted hydrogen chloride
·049· 中西医结合学报2012年8月第10卷第8期 Journal of Chinese Integrative Medicine,August 2012,Vol.10,No.8
was added into it.After shaking,the extract was
filtered and filtrate tests were performed for detection
of various constituents using conventional protocol of
Wagners,Hagners,and Dragendorffs tests for
alkaloids;Baljets,Borntragers and Legals
tests for glycosides;foam,bromine water and
hemolytic tests for saponins;Salkowskis and
Lieberman-Buchard tests for steroids and triterpenoids;
gelatin,potassium dichromate,ferric chloride
and lead acetate tests for tannins;ferric chloride,
alkaline reagent,lead acetate solution and Shinoda
tests for flavonoids;Molischs test and Benedicts
test for carbohydrates;Milons and ninhydrin
tests for proteins and amino acids respectively[19].
1.5 Acute toxicity study Acute toxicity study was
carried out according to the Organization for Economic
Co-Operation and Development(OECD )Guide-
lines No.423[20].Three animals were used for each
step.The dose level to be used as the starting dose
was selected from one of four fixed levels,namely,
5,50,300,and2 000 mg/kg body weight per oral.
As per the OECD recommendations,we used
300 mg/kg of the extract as the starting dose.
1.6 Antidiabetic study
1.6.1 Animal grouping and administration Al
the animals were fasted overnight before the
administration of streptozotocin(STZ),an antibiotic
that can cause pancreaticβ-cel destruction,which
is widely used experimentaly as an agent capable
of inducing insulin-dependent DM,namely type 1
DM[21].STZ was prepared in cold citrate buffer
(pH4.45,0.1 mol/L)and was injected intraper-
itonealy in the dose of 55 mg/kg to different
experimental groups of animals,while the normal
control animals were injected only with citrate
buffer(pH4.45,0.1 mol/L).After 48 h of STZ
injection,blood samples were colected,and serum
glucose level was estimated.Animals with serum
glucose more than 2.5 g/L were considered as
diabetic and used for further study[22].
 After eight weeks of STZ injection to establish
the diabetic rat model,and citrate buffer injection to
the normal controls,animals were divided into six
groups with six in each as folows,namely,normal
control group received 5 mL/(kg·d)of 2%gum
acacia per oral;diabetic control group received
5 mL/(kg·d)of 2%gum acacia per oral;200 mg/kg
of EECT group received 200 mg/(kg·d)of EECT
per oral for two weeks;400 mg/kg of EECT group
received 400 mg/(kg·d)of EECT per oral for two
weeks;metformin group received200 mg/(kg·d)of
metformin per oral for two weeks;piracetam
group received 200 mg/(kg·d)of piracetam per
oral for two weeks.
1.6.2 Serum glucose estimation Serum glucose
was estimated before and after the STZ injection
in diabetic controls and 200 and 400 mg/kg of
EECT-treated animals.For blood glucose level
measurement,animals of al groups were anesthetized
with anesthetic ether and the blood was withdrawn
by puncturing retro-orbital plexus by using fine
glass capilary and colected in epindorff tubes.
The blood was alowed to clot at room temperature
and the serum was separated by centrifugation at
3 000×g for 10 min and was used for estimation
of serum glucose by glucose oxidase and peroxidase
oxidase enzymatic method[23].
1.6.3 Body weight measurement Al animals
were weighed before STZ injection and then on
the 57th(pre-treatment)and71st days(post-treatment)
after STZ injection.Animals were weighed gravi-
metricaly by using electronic digital balance
[24].
1.7 Neurochemical and antioxidant study
1.7.1 Obtaining supernatant Post-treatment
animals were sacrificed by cervical dislocation and
the brain was isolated and weighed.Whole brain
was rinsed with ice cold saline(0.9%sodium chloride)
and homogenized in chiled phosphate buffer(pH
7.4)to adjust the concentration to 20 mg/mL.
The homogenates were centrifuged at 800×g for
5 min,and then the nuclear debris was separated
at 4℃.The supernatant obtained was centrifuged
at 10 500×g for 20 min at 4℃.Such obtained
supernatant was then used for neurochemical and
antioxidant studies[25-28].
1.7.2 Acetylcholinesterase assay For estimation
of acetylcholinesterase activity,Elmans method
named after George Elman was used[25].A total
of 0.4 mL supernatant was added to a cuvette
containing 2.6 mL of phosphate buffer(0.1 mol/L,
pH8)and100μL of 5,5′-dithiobis-(2-nitrobenzoic
acid).The contents of the cuvette were mixed
thoroughly by bubbling air and the absorbance
was measured at 412 nm by a spectrophotometer.
When the absorbance reaches a stable value,it
was recorded as the basal reading.The substrate
of 20μL of acetylthiocholine iodide was added
and the changes in absorbance were recorded for
aperiod of 10 min at intervals of 2 min.Change
in the absorbance per minute was thus determined.
 The mean change in absorbance was considered
for calculation using the folowing formula and
the acetylcholinesterase activity was measured as
micromole per liter per minute per gram tissue[25]:
R=5.74×10-4×ΔACo
 In the above formula,R means the rate,in
moles substrate hydrolyzed per minute per gram
tissue;ΔA means the change in absorbance per
minute,and Co is the original concentration of
tissue(20 mg/mL).
1.7.3 Lipid peroxide levels The thiobarbituric
acid reactive substance(TBARS)level was measured
as an index of MDA production,an end product
of lipid peroxidation.MDA reacts with thiobarbituric
acid to form a red colored complex.The measurement
of MDA levels by thiobarbituric acid reactivity is
the most widely used method for assessing lipid
peroxidation.And then0.5 mL of Tris hydrochloric
·149·中西医结合学报2012年8月第10卷第8期 Journal of Chinese Integrative Medicine,August 2012,Vol.10,No.8
acid was added in 0.5 mL of supernatant and
incubated at 37℃for 2 h.After incubation,1 mL
of 10%trichloroacetic acid was added and centrifuged
at 3 000×g for 10 min,and then1 mL of 0.67%
thiobarbituric acid was added to 1 mL of the
supernatant.The tubes were kept in boiling water
for 10 min.After cooling,1 mL of double distiled
water was added and the absorbance was measured at
532 nm.The MDA concentration of the samples
was derived from the standard curve prepared
using known amounts of MDA and expressed as
nanomolar MDA per miligram protein[26].
1.7.4 SOD level One mililiter of sodium carbonate
(1.06 g sodium carbonate in100 mL water),0.4 mL
of 24 mmol/L nitroblue tetrazolium (NBT)and
0.2 mL of ethylenediaminetetra-acetic acid(EDTA,
37 mg EDTA in 100 mL water)were added to
100μL of supernatant,and0min reading was taken
at 560 nm.Reaction was initiated by addition of
0.4 mL of 1 mmol/L hydroxylamine hydrochloride,
then incubated at 25℃for 5 min and the reduction
of NBT was measured at 560 nm.The SOD activity
of the samples was derived from the standard
curve prepared using known amounts of SOD and
expressed as miligram per microgram protein[27].
1.7.5 CAT level The ability of CAT to decompose
the hydrogen peroxide to water and oxygen was
estimated by determining the decomposition of
hydrogen peroxide at 240 nm.CAT activity was
assayed by the method of Claiborne.One mililiter
of 0.019 mol/L hydrogen peroxide and 0.05 mL
of 10% supernatant were added to 1.95 mL of
phosphate buffers(0.05 mol/L,pH7.0)to make
a final volume of 3 mL.Changes in absorbance
were recorded at 240 nm and expressed as miligram
per microgram protein.The CAT activity of the
samples were derived from the standard curve
prepared using known amounts of CAT and
expressed as miligram per microgram protein[28].
1.8 Cognitive study
1.8.1 Animal grouping and administration The
EECT was tested for cognitive activity using rats
as per the method suggested by Hritcu et al
[29],
Morris et al[30 ]and Tuzcu et al[31].The selected
animals were divided into six groups with six in
each.The normal and diabetic control groups
received 5 mL/(kg·d)of 2% gum acacia per
oral.The standard groups received metformin and
piracetam at the dose of 200 mg/(kg·d)and the
test groups received the EECT at the doses of 200
and 400 mg/(kg·d)per oral.
1.8.2 Y-maze test Short-term spatial working
memory (SWM )was assessed by spontaneous
alternation behavior in the Y-maze task.The Y-
maze used in the present study consisted of three
arms(35 cm in length,25 cm in height and10 cm
in width),and an equilateral triangular central
area.Animal was placed at the end of one arm
and alowed to move freely through the maze.
Time limit in Y-maze test was fixed to 8 min
hence every session ended after 8 min.An arm
entry was counted when the hind paws of the rat
were completely within the arm.Spontaneous
alternation behavior was defined as entry into al
three arms on consecutive choices.The number of
maximum spontaneous alternation behaviors was
then the total number of arms entered minus two.
Percent spontaneous alternation was calculated as
(actual alternations/maximum alternations )×
100%[29].The training was given for 5 d and
percent spontaneous alternation was measured on
the 71st and 75th days.
1.8.3 Morris water maze test On the 71st day,
ratsspatial reference memory(SRM)was tested
in a spatial version of the Morris water maze.The
apparatus consisted of a circular water tank(180 cm
in diameter and 60 cm in height).A platform
(12.5 cm in diameter and38 cm in height)invisible
to the animals was set inside the tank and filed
with water maintained at(28±2)℃at a height
of 40 cm.The tank was located in a large room
where there were several brightly colored cues
external to the maze;these were visible from the
pool and could be used by the animals for spatial
orientation.The position of the cues was kept
unchanged throughout the experiment.The water
maze task was carried out for five consecutive
days after treatment.The animals received daily
training trials for four of these five consecutive
days,with each 90 s trial and a trial interval of
approximately 30 s.For each trial,each animal
was put into the water at one of four starting
positions,the sequence of which being selected
randomly.During test trials,animals were placed
into the tank at the same starting point,with
their heads facing the wal.The animal had to
swim until it climbed onto the platform submerged
underneath the water.After climbing onto the
platform,the animal alowed to remain there for
20 s before the commencement of the next trial.
The escape platform was kept in the same position
relative to the distal cues.If the animal failed to
reach the escape platform within the maximaly
alowed time of 90 s,it was gently placed on the
platform and alowed to remain there for the
same time.The time to reach the platform(latency
in seconds)was measured.A probe trial was per-
formed wherein the extent of memory consolida-
tion was assessed.In the probe trial,the animal
was placed into the pool as in the training trial,
except that the hidden platform was removed from
the pool.The transfer latency(TL)to reach platform
was measured on the 75th day to study SRM
[30,31].
1.9 Statistical analysis Data were expressed as
mean±standard error of mean.Statistical analysis
was performed using one-way analysis of variance
folowed by Dunnetts test.When P<0.05,it was
considered to have significant statistical difference.
Al statistical analysis was performed with OpenEpi
software.
·249· 中西医结合学报2012年8月第10卷第8期 Journal of Chinese Integrative Medicine,August 2012,Vol.10,No.8
2 Results
2.1 Phytochemical analysis The total of extract
yield was 3.7% (weight ratio).Phytochemical
screening of the extract determined presence of
alkaloids,glycosides,steroids and flavonoids as
major constituents,while tannins,triterpenoids,
saponins,carbohydrates,proteins and amino acids
were found absent.
2.2 Acute toxicity study The results of acute
toxicity study showed no clinical signs of toxicity
and mortality in the EECT-treated rats even after
administration of 2 000 mg/kg dose.Hence,as
per OECD guidelines,lethal dose was assigned to
be more than 2 000 mg/kg.One-tenth and one-
fifth of this lethal dose,namely,200 and400 mg/kg
were taken as effective doses for the study.
2.3 Antidiabetic study
2.3.1 Serum glucose estimation After induction
of diabetes on the 71st day,the serum glucose level
was highly elevated in the diabetic animals(P<
0.01).After treated with 200 and 400 mg/kg of
EECT,the serum glucose level was dose dependently
decreased compared to that of the diabetic controls
(P<0.05,P<0.01).And200 mg/kg of metformin
significantly decreased the serum glucose level(P<
0.01),while 200 mg/kg of piracetam showed
statisticaly insignificant effect on serum glucose level
in diabetic rats.See Table 1.
Table 1 Effect of two-week treatment of
EECT on serum glucose level in rats
(Mean±standard error of mean)
Group  n  Serum glucose level(mg/dL)
Normal control  6  94.20±6.96
Diabetic control  6  280.60±18.11**
EECT(200mg/kg) 6  153.60±22.59△
EECT(400mg/kg) 6  125.20±19.26△△
Metformin(200mg/kg) 6  80.88±7.53△△
Piracetam(200mg/kg) 6  248.50±14.59
  **P<0.01,vs normal control group;△P<0.05,△△P<0.01,
vs diabetic control group.EECT:ethanol extract of Clitorea ternatea.
2.3.2 Body weight measurement STZ-induced
diabetes significantly reduced body weight in the
diabetic animals as compared with the normal
controls (P<0.01).After two weeks of treat-
ment with 400 mg/kg of EECT and 200 mg/kg of
metformin,there was a significant increase in
body weight of the rats in the treatment groups
compared to that of the diabetic control rats(P<
0.01),while piracetam and 200 mg/kg of EECT
could not produce any significant effect on body
weight.See Table 2.
2.4 Neurochemical-antioxidant study
2.4.1 Acetylcholinesterase assay Acetylcholinesterase
activity was significantly increased in diabetic controls
when compared with the normal controls(P<0.01).
Two weeks of repeated treatment with 200 and
400 mg/kg of EECT showed a significant decrease
in acetylcholinesterase activity in diabetic animals
(P<0.05,P<0.01),and200 mg/kg of piracetam-
treated group showed a significant decrease in
acetylcholinesterase activity (P<0.01),whereas
200 mg/kg of metformin-treated group did not show
the significant effect in this regard.See Table 3.
Table 2 Effect of two-week treatment
of EECT on body weight in rats
(Mean±standard error of mean)
Group  n  Body weight(g)
Normal control  6  206.00±6.78
Diabetic control  6  150.00±7.07**
EECT(200mg/kg) 6  164.00±9.27
EECT(400mg/kg) 6  207.00±11.58△△
Metformin(200mg/kg) 6  204.00±5.09△△
Piracetam(200mg/kg) 6  160.00±8.94
  **P<0.01,vs normal control group;△△P<0.01,vs diabetic
control group.EECT:ethanol extract of Clitorea ternatea.
Table 3 Effect of EECT on acetylcholinesterase
activity in ratsbrain
(Mean±standard error of mean)
Group  n
Acetylcholinesteras
(μmol/(L爛min爛g)of tissue)
Normal control  6  3.67±0.47
Diabetic control  6  6.36±0.30**
EECT(200mg/kg) 6  5.45±0.25△
EECT(400mg/kg) 6  4.07±0.42△△
Metformin(200mg/kg) 6  6.65±0.44
Piracetam(200mg/kg) 6  3.15±0.20△△
  **P<0.01,vs normal control group;△P<0.05,△△P<
0.01,vs diabetic control group;EECT:ethanol extract of Clitorea
ternatea.
2.4.2 TBARS,SOD and CAT levels The results
showed a significant increase in TBARS level,
and significant decreases in SOD and CAT levels
in the diabetic controls compared to those of the
normal controls(P<0.01).Two weeks of treat-
ment with 400 mg/kg of EECT showed a signifi-
cant decrease in TBARS level and improvement in
SOD and CAT levels (P <0.01),whereas
200 mg/kg of EECT caused a significant reduction
in TBARS level(P<0.01),a significant increase
in CAT (P<0.05)and no significant increase in
SOD level in the diabetic animals.After treated with
200 mg/kg of metformin and piracetam,it showed a
significant reduction (P<0.01)in TBARS level
while a significant increase in SOD level in the
diabetic animals(P<0.01).See Table 4.
2.5 Cognitive studies
2.5.1 Y-maze test The percent of spontaneous
alternation of the diabetic controls was significantly
decreased in retention trial as compared to the
normal controls(P<0.05).The 200 and400 mg/kg
of EECT-,200 mg/kg of metformin-and piracetam-
treated diabetic animals showed significant increases
in the percentage of spontaneous alternations in
retention trial as compared to that of the diabetic
controls(P<0.05,P<0.01).See Table 5.
·349·中西医结合学报2012年8月第10卷第8期 Journal of Chinese Integrative Medicine,August 2012,Vol.10,No.8
Table 4 Effects of EECT on TBARS,SOD and CAT levels in rats
(Mean±standard error of mean)
Group  n  TBARS(MDA nmol/mg of protein ) SOD(μg/mg of protein ) CAT(μg/mg of protein)
Normal control  6  23.83±0.57  108.40±0.37  4.33±0.05
Diabetic control  6  52.70±2.36** 47.85±2.98** 2.19±0.26**
EECT(200mg/kg) 6  35.50±2.09△△ 52.35±7.48  3.87±0.65△
EECT(400mg/kg) 6  25.14±0.27△△ 86.61±1.09△△ 3.46±0.28△△
Metformin(200mg/kg) 6  39.88±0.38△△ 83.99±1.05△△ 3.72±0.05△△
Piracetam(200mg/kg) 6  25.80±0.32△△ 61.37±0.50△△ 2.64±0.34
  **P<0.01,vs normal control group;△P<0.05,△△P<0.01,vs diabetic control group.EECT:ethanol extract of Clitorea ternatea.
TBARS:thiobarbituric acid reactive substance;SOD:superoxide dismutase;CAT:catalase;MDA:malondialdehyde.
Table 5 Effects of EECT on spontaneous alternations
tested by Y-maze test in rats
(Mean±standard error of mean)
Group  n  Spontaneous alternations(%)
Normal control  6  50.40±10.50
Diabetic control  6  34.27±2.52*
EECT(200mg/kg) 6  52.50±5.83△
EECT(400mg/kg) 6  58.98±6.77△
Metformin(200mg/kg) 6  56.24±9.10△
Piracetam(200mg/kg) 6  61.76±1.57△△
  *P<0.05,vs normal control group;△P<0.05,△△P<0.01,
vs diabetic control group.EECT:ethanol extract of Clitorea ternatea.
2.5.2 Morris water maze test There was no
significant statistical difference observed in TL in
animals during the training.On the 75th day,TL
was found to be significantly increased in the
diabetic controls as compared with the normal
controls(P<0.01).After two weeks of repeated
treatment with 200 and 400 mg/kg of EECT and
200 mg/kg of piracetam,TL was significantly
decreased in retention trial as compared with that
of the diabetic controls (P<0.05,P<0.01),
and this effect was found insignificant in200 mg/kg
of metformin-treated animals (P>0.05).See
Table 6.
Table 6 Effects of EECT on transfer latency
in Morris water maze test in rats
(Mean±standard error of mean)
Group  n  Transfer latency(s)
Normal control  6  54.2±4.54
Diabetic control  6  77.8±1.42**
EECT(200mg/kg) 6  63.2±6.00△
EECT(400mg/kg) 6  56.4±1.28△△
Metformin(200mg/kg) 6  68.8±3.83
Piracetam(200mg/kg) 6  52.6±2.65△△
  **P<0.01,vs normal control group;△P<0.05,△△P<0.01,
vs diabetic control group.EECT:ethanol extract of Clitorea ternatea.
3 Discussion
 The incidence of cognitive dysfunction or dementia
appears to be doubled in elderly subjects with
DM[32,33].Hyperglycemia in DM results in over-
production of oxygen free radicals,which con-
tributes to the progression of diabetes.The devel-
opment of complications during diabetes is also
associated with oxidative stress.The neurodegen-
erative disease as Alzheimers disease or dementia
has also been related to oxidative stress during DM
[34].
The neurochemical changes causing cerebrovascular
alterations are also considered as potential mechanism
for diabetic cognitive decline[32,33].
 Antidiabetic,psychotropic drugs,antioxidants
like vitamins A,C,and E and SOD,CAT enzymes
have been found to prevent the progression of
diabetes and the occurrence of complications
resulted from DM[35].However these drugs are
associated with several adverse effects which have
provocated research in field of traditional systems
of medicine to deduce the drugs with less toxicity
and better tolerability.
 From the vast array of materia medica of the
indigenous system,many plants have been reported
to have activity against DM and central nervous
system disorders thus act as very useful remedies
for the aleviation of human suffering.Clitorea
ternateais one of them and the effects of Clitorea
ternatealeaves have been reported to decrease the
levels of blood glucose and glycosylated hemoglobin
significantly and increase the serum insulin to
normal level in aloxan-induced diabetic animals[17].
The methanolic extract of Clitorea ternatea has
been studied for its effect on cognitive behavior,
anxiety,depression,stress and convulsions induced by
pentylenetetrazol and maximum electroshock.The
effect of Clitorea ternatea was also studied on behavior
mediated by dopamine,noradrenaline,serotonin
and acetylcholine[13].Hence it was thought worth to
investigate the effects of Clitorea ternatea on diabetes-
induced cognitive decline in experimental animals
along with its role in oxidative stress and acetylcho-
linesterase activity.The cognitive decline study
was focused on SWM-and SRM-based mazes.
 The preliminary phytochemical screening showed
presence of alkaloids,glycosides,flavonoids,steroids
in the Clitorea ternatealeaves.Various phytochemicals
like phenolic compounds anthocyanin glycosides
known colectively as flavonoids,pentacyclic trit-
erpenoids,and phytosterols have been reported
from this plant[12,36].It is wel documented that the
flavonoids exhibit a hypoglycemic activity and
reverse the diabetic effects on TBARS,SOD and
CAT enzyme levels[36,37],and these findings are in
agreement with results of the current study.The
·449· 中西医结合学报2012年8月第10卷第8期 Journal of Chinese Integrative Medicine,August 2012,Vol.10,No.8
literature survey revealed cognitive impairment in
STZ-induced diabetic animals in eight weeks[38].
Current study as wel reflected the similar results in
diabetic animals.Treatment with Clitorea ternatea
was scheduled for two weeks after cognitive decline.
Results of the present study showed significant
improvement in SWM and SRM,suggestive of
nootropic activity of EECT in diabetes-induced
cognitive decline models.
 The increased oxidative stress in diabetes produces
oxidative damage in many regions of brain including
the hippocampus[9],and this oxidative damage in
the brain is increased by experimentaly induced
hyperglycemia[39].Oxidative damage to various
brain regions constitutes into the long term com-
plications,morphological abnormalities and memory
impairments.In the present study,TBARS level
was significantly increased (P<0.01),whereas
SOD and CAT levels were markedly reduced in
the brain of the diabetic controls.Treatment with
EECT significantly reversed these effects.Therefore,
EECT might have protected DM-induced cognitive
decline by reducing oxidative stress and the flavonoids
detected in the EECT may be the phytoconstituent
responsible for this effect.
 Release of acetylcholine in the hippocampus is
positively correlated with training on a working
memory task
[40]and with good performance on a
hippocampus-dependent,spontaneous alternation
task[41].In diabetic condition,the acetylcholines-
terase level was found to be high,as this enzyme
hydrolyses acetylcholine present in the brain and
results in cognitive decline[42].We observed a
significant rise in acetylcholinesterase activity in
the brain of the diabetic animals.Two-week
treatment with EECT attenuated the increase in
acetylcholinesterase activity in the brain of the
diabetic animals.This decrease in acetylcholinesterase
activity is attributed to flavonoids content of the
extract[43].Thus,EECT treatment for ameliorating
the cognitive decline,cholinergic dysfunction,
and oxidative stress in the diabetic animals may
innovate the clinical application in treating neuronal
deficit in the diabetic patients.
4 Competing interests
 The authors declare that they have no competing
interests.
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·649· 中西医结合学报2012年8月第10卷第8期 Journal of Chinese Integrative Medicine,August 2012,Vol.10,No.8
蝶豆根改善链脲霉素诱导的糖尿病模型大鼠认知减退
Karuna A.Talpate1,Uma A.Bhosale2,Mandar R.Zambare1
1.Department of Pharmacology,Sinhgad Colege of Pharmacy,Vadgaon,Pune 411041,Maharashtra,India
2.Department of Pharmacology,Smt.Kashibai Navale Medical Colege and General Hospital,Narhe,Pune 411041,
Maharashtra,India
目的:研究蝶豆根叶治疗糖尿病的功效,对影响神经系统的化学物质的抗氧化作用,以及缓解因糖尿病引起
的认知减退的作用。
方法:通过测定实验大鼠血清葡萄糖浓度和体质量研究蝶豆根乙醇提取物的抗糖尿病活性。通过Y字形迷
宫以及莫里斯水迷宫测试分别评估蝶豆根对实验大鼠空间记忆以及空间参考记忆的影响;其对影响神经系
统的化学物质的抗氧化作用则通过乙酰胆碱酯酶实验以及糖尿病模型大鼠的脂类过氧化物、超氧化物歧化
酶和过氧化氢酶水平来测定。
结果:服用200和400mg/kg的蝶豆根提取物后,糖尿病模型大鼠血清葡萄糖水平明显降低(P<0.01),且
服用400mg/kg蝶豆根提取物的糖尿病模型大鼠的体质量有明显增加(P<0.01)。蝶豆跟提取物可以显著
改善实验大鼠的空间记忆以及空间参考记忆(P<0.05,P<0.01)。与糖尿病模型对照组相比,服用200和
400mg/kg蝶豆根提取物的糖尿病模型大鼠,其乙酰胆碱酯酶、脂类过氧化物显著减少(P<0.05),过氧化
氢酶水平显著增加(P<0.05或P<0.01);服用400mg/kg蝶豆根提取物的糖尿病大鼠的超氧化物歧化酶
水平增加(P<0.01)。
结论:蝶豆根具有抗糖尿病、抗氧化的作用,并可改善由糖尿病引起的认知减退,其机制还需要进一步的
研究。
关键词:糖尿病;降血糖药;植物,药用;神经行为学表现;大鼠,Sprague-Dawley
·749·中西医结合学报2012年8月第10卷第8期 Journal of Chinese Integrative Medicine,August 2012,Vol.10,No.8