Antidiabetic Activity of Psidium Guajava (Guava) Leaves Extract
Karunakar Shukla1* and PK Dubey2
*1Mahakal
Institute of Pharmaceutical Studies Ujjain (M.P.) 456664
2Vivekanand College of Pharmacy, Indore (M.P.)
ABSTRACT
Psidium guajava leaves extracts were investigated for hypoglycemic
activity. Aqueous extract and ethanolic extract of leaves were prepared and
screened for hypoglycemic activity. Psidium
guajava therapy not only produces blood glucose
homeostasis but also reversed metabolic and pathologic changes that took place
in pancreatic islets. β-cell secretary activity
resumed near normal as evidenced electron microscopic studies. In diabetic
albino rats, mean percentage reduction in blood glucose level was found to be
18.88 % and 9.19+% for ethanolic and aqueous extracts respectively. The
effect was initiated from first day and increase simultaneously up to
thirteenth day. The hypoglycemic effect of ethanolic extract was better
compared to same dose of aqueous extract. Blood glucose monitoring
and electron-microscopic studies proving that Psidium guajava manifests its beneficial
activity through β-cell rejuvenation, regeneration and stimulation.
Keywords:
Psidium guajava, hypoglycemic activity, ethanolic extract, aqoeus extract.
INTRODUCTION:
Psidium guajava also called as guava belonging
to family Myrtaceae is cultivated in all over
India, the middle portion of the country is the most favorable for the
production of delicious fruits, bark, seeds and leaves of the tree are most
commonly used in Ayurveda and folk practices in India
(1). Psidium guajava commonly
known for its delicious fruits that are
sweet with a flavour cooling aphrodisiacs in action.
The leaves and bark of the guava tree have a long history of medicinal use that
is still employed today. The presence of triterpenoides
in leaves extract of Psidium guajava has been reported (2). Siddiqui et.al.studied
hypoglycemic effects of aqueous extract of leaves of Psidium
guajava the glycemic
control caused by Psidium guajava leaves was not significant (3).
However, dsespite these interesting health values,
very few scientific studies have been carried out to determine the
pharmacological activity involved in the hypoglycemic effects. The present
study was carried out in order to investigate in vivo-hypoglycemic activity of Psidium guajava leaves methanolic
and aqueous extracts,in alloxan induced diabetic rat models.
MATERIALS AND METHODS:
Materials: Alloxan, polyvinyl pyrrolidine, tolbutamide, haemo glucotest strip, petrolium ether and ethanol.
Methods:
Hypoglycemic activity
is evaluated by changes in blood sugar levels in the experimental animals after
administration of the test drug. The levels are determined before and after
drug administration at regular intervals. For screening of hypoglycemic
activity of aqueous extract and ethanolic extract in normal and alloxan induced diabetic rats, alloxan
induced diabetes models were employed. This model has been successfully
employed for the evaluation of many plant originated and synthetic drugs. The
advantage of this method is that, this method can be performed in normal
laboratory condition (4).
Table-1
observation of blood glucose level in alloxan induced
diabetic albino rats.
|
Group |
NBGL Mg/dl |
AIBGL Mg/dL |
First Day (mg/dl) |
Third Day (mg/dl) |
Fifth Day (mg/dl) |
Seventh Day (mg/dl) |
Ninth Day (mg/dl) |
Eleventh Day (mg/dl) |
Thirteenth Day (mg/dl) |
Fifteenth Day (mg/dl) |
|
Control |
103+6.14 |
268.67+ 5.13 |
268.67 +
6.15 |
265.33 +10.36 |
264.66 +9.15 |
262+ 5.19 |
260.67 +15.3 |
261.33 + 6.33 |
265.33 + 11.55 |
267.67 + 6.89 |
|
Ethanolic- Extract |
99.5 +8.63 |
264.17 + 9.60 |
264.17 + 6.11 |
257.33 + 8.11 |
248+ 12.11 |
242.33 +11.52 |
230.33 +5.56 |
218.5 +11.89 |
215.14 +13.23 |
214.33 +5.33 |
|
Aqueous extract |
115.16 +9.85 |
263.34 +4.33 |
263.34 +6.45 |
262.83 +11.50 |
256.5 +7.25 |
251.5 +9.15 |
246.33 +15.36 |
243.17 +12.3 |
236.33 +6.45 |
237.23 +6.89 |
|
Tolbutamide |
95.5 +9.33 |
258.33 +11.5 |
258.33 +8.06 |
158.33 +11.23 |
157.67 +13.25 |
154.33 +9.63 |
149.67 +11.9 |
150.67 +12.56 |
149.33 +9.63 |
153.43 +8.78 |
All the values are
represented as in Mean + S.D.
and n=6.
Table-2 Percentage reduction of Blood glucose level
in alloxan induced diabetic albino rats.
|
Group |
Blood glucose level (before treatment) |
Blood glucose level (after treatment) |
Percentage reduction in blood glucose level |
|
Control |
268.67+5.13 |
267.67+6.89 |
0.37 % |
|
Ethanolic extract |
264.17+9.60 |
214.33+5.33 |
18.88 % |
|
Aquous
extract |
263.34+4.33 |
237.23+6.89 |
9.91 % |
|
Tolbutamide |
258.33+11.5 |
153.43+8.78 |
40.60 % |
EXPERIMENTAL:
A) Preparation of
doses:
One gram of ethanolic
extract, and aqueous extract were separately triturated with polyvinyl pyrrolidine (PVP 0.2 g) and added water for injection in
success amount to make up the final volume to 100 ml (0.2%w/v).
B) Administration of
doses:
Toxicological studies
revealed that albino rats tolerated considerably high dose of aqueous extract
(400 mg/kg body weight, i.p.) and ethanolic extract
(400 mg/kg body weight,i.p.)
with out any toxic manifestation. There fore doses of 300-mg/kg-body weight i.p.of ethanolic extract and aqueous extract were
administered to the normal and alloxan induced
diabetic albino rats.
C) Experimental animal:
Adult albino rats of
either sex (100-200 Gms) were selected for the study
and were divided in to groups of six in each group. Rats were acclimatized for
a period of two-three days in the new environment and subsequently used for
further study.
Group-I: Control:
Adult albino rats were
fed with polyvinaylpyrolidine (PVP) solution
(0.2%w/v).
Group-II: Aqueous extract treated:
Adult albino rats were
interperitonaly administered with aqueous extract,
300 mg/kg of body weight.
Group-III: Ethanolic extract treated:
Adult albino rats were
interperitonaly administered with ethanolic extract,
300 mg/kg of body weight.
Group-IV: Tolbutamide treated:
Adult albino rats were
orally administered with tolbutamide, 250 mg/kg of
body weight.
D) Induction of alloxan diabetes:
The diabetes was
experimentally induced by i.v. administration of alloxan monohydrate 100 mg/kg of body weight. Alloxan is given by rapid intravenous injection, as its
half-life in the body is only a few minuets. The diabetes is induced within 24
hours if the rats were fasted before the alloxan
injection. There must be a specific damage of insulin producing β-cells.
E) Sample
collection:
Sample
collected by withdrawn of blood from the tail vein of animal using disposal
syringe at least after 12 hours of fasting.
F) Estimation of blood glucose level:
Fasting blood glucose
level was estimated by HGT (Haemo gluco
test 200-800R) Method.
Haemo gluco test 200-800R(HGT) method:
In this method, the
blood glucose level was estimated using a one touch blood glucose monitoring
system. Haemo glucotest strip
for glucose in blood stored at +20C to 30C blood glucose
level evaluated with glucometer. Place one drop of
blood on the test strip and monitor the blood glucose level on the screen of
the glucometer.
G) Procedure:
Adult albino rats of
either sex (100-200g) were divided into group of six albino rats in each group.
All the animals were kept in fast condition for 18 hours (over night) before
giving the test drug but water was freely permitted. The concentration
(300mg/kg of body weight) was prepared for ethanol extract and aqueous extract
respectively. One group was kept as the control and was given vehicle (0.2% w/v
PVP) alone. Blood sample were collect from the tail vain by disposal syringe
before and after 24 hours of drug administration.
The initial blood
glucose level was determined after 24 hours of drug administration and the
study was continued for a fifteen days after fixed intervals of two days(first,
third,…….fifteenth),days. The blood glucose level was evaluated by Haemo gluco test 200-800R (HGT)
method.
E) Histopathological
Studies:
In normal albino rats
the islets of langerhans have normal capsules. There
are normal well-defined β-cells distributed in good number below the
capsule in islets of langerhans. The cell cytoplasm
showing granules in large numbers and normal oval shaped nucleus is visible.
Blood vessels in the capsules are normal in diameters.
In
control albino rat’s effect of alloxan monohydrate is
quit obvious, there was a significant decrease in the number of insulin
granules in the b-cells of control diabetic rats
with an occasional gap in the cell clusters indicating absence of b-cells due to necrosis.
Albino rats which were
previously treated with alloxan monohydrate, was than
treated with crude methanol extract have a definite effect on Islets of langerhans. Almost normal cells but definite cell membrane
and large nucleus are shown. Cytoplasmic material
though not as granular as normal but granulation is visible. It seems that the
content of the plant present in the methanol extract either protect the cells
from toxic effect of alloxan monohydrate or the cells
to reorganize after detoxifying the compound.
In albino rats treated
with aqueous extract plasma membrane of clear boundaries was seen at many
places. At some places it looks like that the plasma membrane is torn out. Cytoplasmic material is spread in the vicinity. Not very
clear nucleus is visible but in some cells a gradual definite appearance of
nucleus observed.
The photograph of
pancreatic islets of albino rats treated with ethanolic extract showed
considerable improvement in b-cell activity. The
numbers of insulin granules were significantly high as well as b-cell
population. The islets size always larger. This is
probably due to regeneration rejuvenation of b-cell leading to
increased insulin production and secretion.
Percentage reduction of Blood glucose level in alloxan induced diabetic albino rats.
RESULTS AND DISCUSSION:
In the present work we describe the hypoglycemic activity of the methanolic and aqueous extracts of the Psidium
guajava in alloxan
induced diabetic rats. As shown in the table the methanolic
and aqueous extracts significantly reduced the blood glucose level in alloxan induced diabetic rats. Both the extracts
were administered through interaperitoneal routs in a
dose of 300 mg/kg of body weight/day with 0.2 % polyvinyl pyrrolidine
solution. The hypoglycemic activity of ethanolic extract observed was better
compared to same dose of aqueous extract,
in diabetic albino rats maximum percentage reduction was found to be 18.88 %
and 9.91 % respectively for ethanolic and aqueous extracts. Moreover after Histopathological studies we observed that, the photograph
of pancreatic islets of albino rats treated with ethanolic extract showed
considerable improvement in b-cell activity. The
numbers of insulin granules were significantly high as well as b-cell
population. The islets size always larger. This is
probably due to regeneration rejuvenation of b-cell leading to
increased insulin production and secretion.
CONCLUSION:
In conclusion, the finding reported in this study indicates that Psidium guajava
extracts given to the alloxan induced diabetic albino
rats may contain novel bioactive principles with hypoglycemic properties.
Although promising results have been obtained more concerned efforts are still
needed for isolation characterization and biological evaluation of the active
principles of the extracts.
REFERENCES:
1.
Kirtikar K.R., Basu
B.D., Indian Medicinal Plant,
Periodical export, New Delhi, Second edition, Vol.4, 1975, pp.235.
2.
Begum
S, Hassan S.I, Siddiqui B.S. “Two New Triterpenoids from The Fresh Leaves of Psidium
guajava”, Journal
of Ethnopharmacology, Vol. 48, Issue 1, August
1995, pp.25-32.
3.
Obatomi D.K, Bikomo
E.O, “Anti-Diabetic Properties of the African Mistletoe in Streptozotocin-induced
Diabetic Rats”. Journal of Ethnopharmacol. Jun 1994, Vol.43 (1), pp.7-13.
4.
Joshi,
K. C. Bansal, R.K. and Patni,
R., J. Ind. Chem. Soc., 1980, 7, 1042-1043.
Received on 23.04.2009
Accepted on 12.06.2009
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