International Journal of Animal and Veterinary Advances 2(3): 59-62, 2010
ISSN: 2041-2908
© M axwell Scientific Organization, 2009
Submitted Date: August 18, 2009
Accepted Date: September 14, 2009
Published Date: July 05, 2010
Evaluation of the Effect of Aqueous-methanolic Stem Bark Extract of
Acacia polyacantha on Blood Glucose Levels of Alloxan Induced
Diabetic Wistar Rats
1
A.O . Okpanachi, 1 A.B . Adelaiye, 1 A.A .U. D ikko , 2 M. Kabiru, 1 A. Mohamm ed and 1 Y. Tanko
1
Departm ent of Human Ph ysiology , Ahmadu B ello U niversity, Zaria, Nigeria
2
Departm ent of Pharmacogno sy, A hmadu Bello University , Zaria, Nigeria
Abstract: This study was undertaken over a 24 h p eriod to evaluate the hypoglycemic effect of aqueousmethanolic stem bark extract of Acacia polyacantha on blood glucose levels of alloxan-induced diabetes rats.
Three doses of the extract (100, 200 and 400 mg/kg) were adm inistered p.o. There was a significant decrease
in the blood glucose levels betw een 8 th to 24th h after treatment with the dose of 400 mg/kg when compared
with the control. Also after the 16th h of treatment there was a significant decrease in th e bloo d gluc ose lev els
with the dose of 200 mg/kg when compared to control. As regards to the dose of 100 mg/kg there was no any
significant decrease in th e bloo d gluc ose lev els when com pared to control. The preliminary phytochemical
screening revealed the presence of alkaloids,anthraquinones, tannins, flavon oids, steroids and saponins. The
median lethal dose (LD 5 0 ) in rats was calculated to be 3.807.9 mg/kg body weight. In conclusion the aqueous
methanolic stem bark extract of Acacia polyacantha possess anti-diabetic effect in alloxan- induced in diabetic
rats.
Key w ords: Acacia polyacantha, hypoglyc emic activity, alloxan, diabetes me llitus, phytoche micals
INTRODUCTON
Diabetes M ellitu s (D M ) is a major health problem all
over the world. Globally, the number of people that have
been diagnosed with diabetes has exploded in the past two
decades. In 2000,151 million has been projected that 221
million people will be diabetic in 2010 and 324 million by
2025 (Zimmet et al., 2001). Several approach es were
made to reduce the hyperglycemia, the hallmark of
diabetes mellitus, with treatment such as sulfonylurea,
which stimulates pancreatic islet cells to secrete insulin;
metformin, which act to reduce hepatic glucose
production; "-gluco sidase inhibitors, wh ich interfe re with
glucose adsorption and insulin itself, which suppresses
glucose production and augment glucose utilization
(Mo ller, 2001). The growing public interest and
awareness of natural products have led pharmaceutical
industry and academic researchers to pay more attention
to medicinal plants (Day, 1998). The apparent reversal
from western to herbal medicine is partly due to the fact
that synthetic drugs have always shown adverse reactions
and other undesirable side effects. This has led the belief
that natural products are safer because they are more
harmonious with biological system. In addition, the cost
of administering modern antidiabetic drugs is beyond the
reach of peo ple in the low income group and those living
in rural areas (Valiathan, 1998). In Nigeria, hundreds of
plants are used traditionally for the management of
diabetes mellitus. To date, however, only a few of these
medicinal plant have received scientific scrutiny, despite
the fact that the world Health Organization has
recommended that medical and scientific examination of
such plan ts should be u ndertaken (WHO , 1980).
Acacia polyacantha is of the fabaceae family a group
of plants called campylac antha . (Coa tes, 2002). It is
com mon ly called “Karo” by the Hausa speaking
communities in No rthern N igeria.T he tree often grows in
the moist, subtropical bushveld of Africa ,usually in
alluvial soils near rivers. It is widespread in tropical
Africa, occurring from Gambia to Ethiopia and
southwards to Kenya and Zimbabwe (Schmidt
et al., 2002). The white-stem thorn is a large, erect tree
that grow s to an average he ight of 10-15 m, exceptionally
large trees m ay reach a height of 25 m. The stem of
younger trees appears yellowish with papery bark and
persisting prickles. As it ge ts older, the bark gets
smoother and w hitish grey, with bark flakes sometimes
present. Young branches are covered in silvery hairs and
the whole tree is covered in dark brown to black hooked
thorns in pairs. The leaves are twice compound with 1435 pairs of pinnae and 20-60 leaflets per pinna. Leave s are
fairly large and arranged singly along the shoots. The
upper surface of the leaves is darker than the underside,
and mostly with hairs on the margins and on the leaf stalk.
The flowers that appear from September to December are
light yellow to cream. The flowers as well as the seedpods
are borne in spikes, which arise from the nodes. They can
appear singly or in clusters of up to four and are swe etly
Corresponding Author: A.O. Okpanachi, Department of Human Physiology, Ahmadu Bello University, Zaria, Nigeria
59
Int. J. Anim. Veter. Adv., 2(3): 59-62, 2010
scented. The white-stem thorn tree yields gum th at is
norm ally used in confectionery and as an adhesive, wh ile
the bark is used in tanning. The roo ts and possibly bark
are used for medicinal and magical purposes. Root
infusion is used to treat snakebites, cough, heamorrhoids
and also to bathe children who are restless at night
(Venter et al., 1996). It has also been used as tablet
binders
the pharm aceu tical
industries (Lew is
et al., 1977).
Studies on the effect of Acacia polyacantha on blood
glucose levels is lacking and the search for suitable
medicinal plants among the polyacantha species against
the incidence of Diabetes Mellitus cannot be over
emphasized.
Anima ls and Induction of diabetes m ellitus: Twenty
five (25) Wistar rats weighing betw een (150-2000 g) of
about 20-25 weeks of age of both sexes was used and was
obtain from the Animal House of the Department of
Pharmac ology and Clinical Pharmacy, A.B.U. Zaria. They
were kept in plastic cages under laboratory condition of
temperature and humidity and placed on standard feed
and allow free access to water with ad libithum.
The animal was fasted for 12-18 h with free access to
water prior to the induction of diabetes which was carried
out by single intraperitoneal injection of Alloxan
dissolved in 0.9% v/v cold normal saline solution at a dose
of 150 mg/kg b.w (Saddique et al., 1987).
Three days after Alloxan injection, the blood glucose
levels was measured using the gluco se-ox idase principle
and only those rats with fasting blood glucose
greater than 200 mg/dl will be included in the study
(Stanley et al., 2001).
The alloxan induced diabetic rats w ere random ly
assigned into five groups (1-5) of five rats (n = 5) each as
follows, namely:
MATERIALS AND METHODS
Plant material: A sam ple of the stem b ark of Acacia
polyacantha was collected w ithin Main campus, Ahmadu
Bello University, Zaria in the month of November 2008.
The plant was identified and authenticated by Mallam
Umar Gallah of the herbarium section in the Department
of Biolo gical Science, Ahmadu Bello University Zaria,
whe re a herbarium specimen was prepared and deposited
there with a voucher number 1905.
Group 1: Diabetic, untreated W istar rats(was given normal
saline,5 ml/kg bodyweight p.o
Group 2: Diabetic to b e treated with 100 mg/kg extract p.o
Group 3: Diabetic to b e treated with 200 mg/kg extract p.o
Group 4: Diabetic to b e treated with 400 mg/kg extract p.o
Group 5:Diabetic to be treated with metformin (250
mg/kg p.o) (Marta et al., (2000); Solskov et al.
(2008).
Extract preparation: The stem bark of Acacia
polyacantha were collected and dried under shade and
ground into powder. The powder (600 g) was macerated
in 30% of distilled water and 70% methanol at room
temperature for 24 h. It was then filtered using a filtered
paper (Whatmann size No.1) and the filtrate evaporated to
dryness in water bath at 60ºC. A brownish residue
weighing 28.5 g was obtained. T his w as kept in air tight
bottle in a refrigerator until used.
Determination of blood glucose levels: All blood sample
were collected from the tail artery of the rats at interval of
0, 2, 4, 8, 16 and 24 h. Determination of the blood glucose
levels was done by the glucose-oxidase principle (Beach
and Turner,1958) using the ONE TOUCH Basic
(Lifescan,MilpitasCA) instrument and results were
expressed as mg /dl (Rheney and K irk, 2000).
Ch em icals used: All chemicals and drug s used w ere
obtained commercially and of analytical grade.
Statistical analysis: Blood glucose levels were expressed
in mg/dl as mean± SEM . The data w ere statistically
analyzed using ANOV A with multiple comparisons
versus control group by Dunnett’s method. The value of
p<0 .05 or p <0.01 were taken as significant.
Phytochemical screening: A preliminary phytochemical
screening of the stem bark extract of Acacia polyacantha
stem bark was also done using standard methods of
analy sis (Trease and Evans, 1989; Sofowora, 19 92).
Acu te toxicity studies: LD 5 0 determination was
conducted using the method of Lorke (1983). In the initial
phase, male and female wistar rats were divided into three
groups of three rats each. T hey were treated with the
Acacia polyacantha stem bark extract at doses of 10, 100
and1000 mg/kg per orally. Animals were observed for 24
h for signs of toxicity. In the second phase of the toxicity
study the animal were grouped into three groups of one
rat each .They were treated with the Acacia polyacantha
stem bark extract at doses of 1600, 2900 and 5000 mg/kg
per orally. A nima ls were observed for 24 h and there was
mortality recorded.
RESULTS
The preliminary phytochemical screening of Acacia
polyacantha stem bark extract revealed the presence of
flavinoids, tannin, anthraquinone, cardiac glycosides
alkaloids, triterpenoids, saponins and reducing sugars.
Acu te toxicity study: Signs of the toxicity were first
noticed after 2-4 h of extract administration. There were
decreased locomotor activity and sensitivity to touch.
Also there was decreased feed intake, tachypnoea and
prostration after 12 h of extract administration.
60
Int. J. Anim. Veter. Adv., 2(3): 59-62, 2010
Table 1: Effect of aqueo us methan olic stem bark extract of Acacia polyacantha on blood glucose levels of alloxan ind uces diabetic W istar rats.
Blood glucose level (mg/dl) taken over 24 h
-----------------------------------------------------------------------------------------------------------------------------------------------------Groups
0
2
4
8
16
24
Control(normal
348.00±37.59
351.80±34.76
351.20±33.79
355.40±39.02
375.20±33.06
378.40±41.67
saline)
100 mg/kg extract
479.80±62.58
406.20±90.39 n s
393.40±91.71 n s
310.40±92.07 n s
366.80±82.51 n s
413.80±92.70 n s
treated
200 mg/kg extract
349.20±73.70
338.80±97.89 n s
353.80±72.05 n s
294.00±68.71 n s
204.51±74.44 a
325.80±108.13 n s
treated
400 mg/kg extract
360.80±48.74
502.80±41.80 n s
393.60±50.63 n s
161.20±22.54 a
201.80±49.05 a
219.20±82.85 a
treated
250 mg/kg
378.20±74.70
178.40±46.79 a
152.40±33.12 a
175.60±44.56 a
221.80±11.43 a
228.40±51.38 a
metformin treated
a
: p< 0.05 = significant, ns = not significant
The LD 5 0 was calculated as 3807.8 mg/kg
blood gluco se leve ls wh en co mpa red to the control. In
regard to the dose of 200 and 400 mg/kg, it significan tly
(p<0.05) lowered the blood glucose level when compared
to control after 16 hours and between 8 and 24 h of
extract administration, respectively.
In conclusion, the present study showed that aqueous
methanolic stem bark extract of Acacia polyacantha
possessed antidiabetic properties which suggest the
presence of biologically active components which may be
worth further investigation and elucidation. The effective
antidiabetic dose was foun d to be 400 mg/k g bodyw eight.
Further studies are currently under way to isolate and
characterized the active components of the crude extract
of this plant.
Blood glucose levels of alloxan induced diabetic Wistar
rats: Table 1 showed the results of the effect of three
doses (100, 200, 400 mg/kg) of aqueous methanolic stem
bark extract of Acacia polyacantha, metformin and
control groups in alloxan diabetic Wistar rats. The doses
of metformin and 100 mg/kg of the extract did not show
any significant change in blood glucose levels when
compared to untreated con trol. How ever, the doses of 200
and 400 mg/kg of the extract showed a significant (p<0.05
and p<0.01) decrease in the blood glucose levels after 16
hours and between 8 and 24 h, respectively.
DISCUSSION
ACKNOWLEDGMENT
Alloxan mon ohydrate is known to induce diabetes by
partial destruction of panc reatic $-cells of islet of
langerhan (Cak ici et al., 1994; A bdel-Ba rry et al., 1997).
This results in decrease insulin levels and hyperglyc emia
leading to type 1 diabetes mellitus. The alloxan- treated
rats, therefore, appear to represent a good laboratory
model for IDDM , experimental diabetes state, w ith
residual or remna nt insulin production by the panc reatic
$-cells.There is possibility for the survival of a few $cells and this has been proved by several workers who
observed antihyperglycem ic activity with oral
hypoglyc emic agents like glibenclamide, tolbutamide etc.
in alloxan-induced diabetic rats (Sheeja and
Augusti,1993; Kumud and Mathew, 1995; Subramoniam
et al.,1996; Prince et al., 1999). The diabetic state of
alloxan- treated diabetic rats is therefore, not the same as
that obtained by total pancreatectom y, as daily
administration of insulin is not required for the survival in
alloxan-treated diabetic animals.
Acacia polyacantha have been shown to have
antihyperglycem ic potential in alloxan diabetic rats by
possibly stimulating the $-cells and or due to its insulinlike activity. Acacia polyacantha at doses of 100, 200 and
400 mg/kg is show n in Table 1. In relation to the diabetic
rats that received 100 mg/kg body weight of the extract of
A. polyacantha, there was no significant change in the
The authors of this work wish to acknowledge the
technical assistance of Mallam Yau M . of the Department
of Physiology, Faculty of Medicine Ahmadu Bello
University, Z aria, Nigeria.
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