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Prime Research on Biotechnology (PRB)
ISSN: 2315-5299. Vol. 2(4), pp. 53-56, December 18th, 2012
www.primejournal.org/PRB
© Prime Journals
Full Length Research
Hypoglycemic activity of aqueous extract of the bark of
Bridelia ferruginea in normal and alloxan-induced
diabetic rats
Adewale OB and Oloyede OI
1Department of Chemical Sciences (Biochemistry unit), College of Sciences, Afe Babalola University, Ado-Ekiti, Ekiti
State, Nigeria.
2Department of Biochemistry, Faculty of Science, Ekiti State University, Ado-Ekiti, Ekiti State, Nigeria.
Accepted 18th October, 2012
The hypoglycemic activity of the aqueous extract from stem bark of Bridelia ferruginea was investigated in both normal
and alloxan-induced diabetic rats. Rats were made diabetic by the administration of alloxan (150mg/kg body weight)
intraperitoneally. Fasting blood glucose level greater than 300mg/dl indicates diabetes mellitus. Diabetic rats were
treated with 100mg/kg of the extract. The extract significantly reduced the blood glucose level of normal rats at the
tested dose 24 hours after oral administration (p< 0.05) from 45.00 + 2.65 to 32.67 + 1.53 mg/dl and also reduced the
blood glucose level of alloxan-induced diabetic rats from 547.50 + 74.25 to 450.00 + 14.14 mg/dl. Glucose tolerance in
normal rats was enhanced which shows that there is marked improvement in glucose utilization after administration of
this extract. The result obtained in this study revealed the mechanism of hypoglycemic activity of Bridelia ferruginea to
repair the β-cells that has been destroyed by the alloxan monohydrate within few hours. This implies that the aqueous
extract from this plant stimulates the reduction of the blood glucose by acting directly as insulin or enhancing the release
of insulin.
Keywords: Hypoglycemic activity, Bridelia ferruginea, alloxan, glucose tolerance, insulin.
INTRODUCTION
Diabetes mellitus is a chronic metabolic disorder
characterize by degeneration of carbohydrates, protein
and fat metabolism (O’Brien and Granner, 1996).
Diabetes being a major degenerative disease is found in
all parts of the world and it is becoming the third most
lethal disease of mankind and rapidly increasing
(Ogbonnia et al., 2008). Hyperglycemia (high blood
sugar) is a condition in which an excessive amount of
glucose circulates in the blood plasma. This is generally a
glucose level higher than 180 mg/dl. Hyperglycemia
causes many of the health problem associated with
diabetes such as heart disease, kidney and nerve
damage. However, hypoglycemia (low blood sugar) is
most common among people with diabetes, as too much
insulin can cause blood sugar levels to fall. However,
hypoglycemia is a condition in which there is an
abnormally low level of glucose (sugar) in blood. If left
untreated, hypoglycemia can cause permanent
neurological damage and death (Dailey, 2007; Bergqvist
et al., 2008). Hypoglycemic agents have been used in the
management of diabetes mellitus (DM).Insulin and oral
hypoglycemic agents like sulphonylureas and biguanides
are still the major players in the management of the
disease. Due to lack of insulin, hyperglycemia and
glycosuria almost invariably occur. The search for a
curative agent against this disease resulted in the
introduction of several hypoglycemic agents. Some of
which are used therapeutically. However, various harmful
side effects and weak effectiveness of them made their
use limited and the search to find more effective agents
continues. Medicinal plants are increasingly being used in
most parts of the world as hypoglycemic agents (Farswan
et al., 2009; Lee et al., 2009). Several plants and isolated
compounds have been demonstrated to have anti-
diabetic potentials (Li et al., 2004; Grover et al., 2000;
Rahman and Zaman, 1989). One of them is taken for
investigation in this study.
Bridelia ferruginea is a tree belonging to the family
Euphorbiaceae. The genius Bridelia is made up of about
60species scattered throughout Asia, Africa and Australia
(Rashid et al, 2000). Bridelia ferruginea is commonly
called “ira” and the bark “eepo ira” in Nigeria among the
Yorubas. It is used in some communities in Cameroon in
the traditional treatment of illness referring to the clinical
diabetes condition (Njamen et al, 2003). Nutritionally,
various parts of this tree are used in the treatment of
illnesses e.g. roots and branches has antibacterial
properties, roots to treat skin diseases, the leaves and
the decoction of the stem bark in the treatment of
diabetes, diarrhea, dysentery, gastrointestinal disorders
and rheumatic pains (Cimanga et al, 1999, Addae-
Mensah and Achenback, 1985). B. ferruginea has been
found to contain rutin (Rashid et al, 2000), which has
been shown to exhibit hypoglycemic activity (Onunkwo et
al, 1996). The leaf extract was shown to contain naturally
occurring secondary metabolites endowed with anti-
diabetic properties (Njamen et al, 2003, Onunkwo et al,
1996). The objective of this study was to examine the
hypoglycemic effect of the bark of Bridelia ferruginea.
MATERIALS AND METHOD
Plant materials
The stem bark of Bridelia ferruginea tree was obtained
from Eniju farmland at Ijurin-Ekiti in Ijero Local
Government of Ekiti State, Nigeria. It was air-dried for
twenty-eight days, ground after removing the outermost
layer. The powdered material was then stored in sealed
bottle at room temperature (370C).
Extraction
Aqueous extract of stem bark of Bridelia ferruginea (5g)
was extracted with 100 ml distilled water and stored in
the refrigerator at 100C for 12hrs. The resulting filtrate
was administered orally to the animals using an intubator
based on the body weight and the dose (100mg/kg body
weight).
Chemicals used
Alloxan monohydrate and α-d-glucose (anhydrous) from
Sigma Chemical Company, St. Louis, Mo, U.S.A. Distilled
water, methylated spirit, and one touch glucose strips.
Each glucose strip contains the following reactive
ingredients in the approximate concentrations: Glucose
oxidase -----14IU, Peroxidase -----11IU, 3-methyl-2-
benzothiazolinone hydrazone hydrochloride ---0.06mg, 3-
dimethylaminobenzoic acid------ 0.12mg.
Laboratory animals
Female albino rats weighing between 100-140g were
used for the study. The animals were obtained from the
animal house of the Department of Biochemistry,
University of Ilorin, Nigeria. The animals were housed at
the Department of Biochemistry, Ekiti State University,
Ado-Ekiti, and were acclimatized for a period of 7days
with free access to pelleted feed and clean water. The
Adewale and Oloyede 54
rats were then grouped randomly into four with four
animals in each. Alloxan monohydrate (150mg/kg body
weight) was dissolved as 5% solution in distilled water
and injected intraperitoneally in previously overnight
fasted rats to induce diabetes. After one hour animals
were allowed food and water ad libitum. After 72hours
Blood glucose levels were estimated by the glucose
oxidase method and animals having blood glucose levels
of more than 150mg/dl were selected for study.
Sixteen female albino rats divided into four groups
(n=4) designated: Group I normal control received only
distilled water, group II received only aqueous extract of
the bark of Bridelia ferruginea (100mg/kg body weight),
groups III and IV were made diabetic by the
intraperitoneal administration of alloxan monohydrate
(150mg/kg body weight). Group III animals were treated
with aqueous extract of B. ferruginea (100mg/kg body
weight) and alloxan diabetic rats of group IV were kept as
diabetic control (untreated). Determination of fasting
blood glucose Fasting blood glucose levels in both
normal and alloxan-induced diabetic rats were
determined routinely by the glucose oxidase method
(using the digital one-touch glucometer). Blood samples
were collected two hours after administration of the
extract by cutting the tip of the tail of each rat. Rats with
blood glucose level above 200mg/dl were considered to
be diabetic and were used in the study.
Oral glucose tolerance test
The oral glucose tolerance test was carried out on normal
and alloxan-induced diabetic untreated group at the same
time. The rats were administered orally with the aqueous
extract of the bark of B. ferruginea at a dose of 100mg/kg
body weight after an overnight fast. Two hours later,
glucose solution (2g/kg body weight) was administered
orally. Blood samples were collected prior to the
administration of the glucose load. Blood glucose values
were determined at 30, 60, 90 and 120 minutes later. The
blood samples were taken by cutting the tip of the tail of
each rat and the blood glucose levels were determined
routinely by the glucose oxidase method.
Statistical analysis
All data were expressed as means ± SD. Student’s t-test
was used to compare the mean values of test groups and
control. Differences in mean values were considered
significant at p < 0.05.
RESULTS AND DISCUSSION
The mean blood glucose levels of control and treated rats
at various time intervals after oral administration of
aqueous extract of the bark of Bridelia ferruginea are
shown in table 1. These levels were compared with the
values in control rats administered distilled water only.
Theglucose levels of normal rats administered B.
ferrugineaaltered blood glucose glucose were found to be
significantly (P<0.05) lowered than the basal value.
55 Prim. Res. Biotech.
Table 1.0: Effect of 5% w/v aqueous extract of the bark of Bridelia ferruginea (100mg/kg body weight) on blood glucose (mg/dl) in normal rats.
0hr
2hr
4hr
6hr
8hr
10hr
12hr
24hr
Control
47.25+4.99
47.00+3.83
47.00+4.55
40.75+2.50
35.00+9.63
36.00+3.14
29.00+14.65
28.50+7.94
Test
45.00+2.65
48.67+2.31
45.00+2.65
39.67+1.53*
39.33+5.13*
42.00+6.56
22.00+5.29*
32.67+5.51*
Each value represents the mean + S.D from 4 rats
Significant different from control: *P < 0.05
Table 2.0: Effect of 5% aqueous extract of the bark of Bridelia ferruginea (100mg/kg body weight) on blood glucose (mg/dl) on alloxan-induced
diabetic rats.
0hr
2hr
4hr
6hr
8hr
10hr
12hr
24hr
Control
558.00+59.40
610.00+14.14
625.00+35.36
598.50+72.83
578.50+30.40
224.00+0.00
304.00+0.00
215.00+0.00
Test
547.50+74.25
620.50+41.72
566.50+47.38
510.50+72.83
474.50+36.06
460.00+12.73
462.50+81.32
450.00+14.14
Each value represents the mean + S.D from 4 rats
Table 3: Glucose values (mg/dl) during oral glucose tolerance test in normal and alloxan-induced diabetic untreated rats.
0min
30mins
60mins
90mins
120mins
Control
48.33+1.53
59.33+2.52
62.67+5.51
54.33+7.64
45.00+5.57
Test (Normal)
51.00+0.00
54.33+7.09
47.00+2.65
51.00+2.65
45.00+2.65
Test (Untreated)
484.67+17.60*
459.33+94.92*
540.33+69.79*
475.33+77.02*
497.33+86.95*
Each value represents the mean + S.D from 4 rats
Significant different from control: *P < 0.05
Table 4: Growth response of Diabetic rats treated with aqueous
extract of the bark of Bridelia ferruginea.
Time
0hr
6hr
12hr
24hr
Control
107
103
138
140
Test
105
114
110
126
This clearly shows that the 5% aqueous extract of the
bark of B. ferruginea produces hypoglycemic effect by the
stimulation of insulin release.The hypoglycemic effects of
Bridelia ferruginea on the blood glucose of alloxan-
induced diabetic rats are shown in Table 2.0.
Administration of 100mg/kg of 5%(w/v) aqueous extract
of B. ferruginea produced a decrease in blood glucose
level of rats. The hypoglycemic effect of the extract was
felt from 6hours after administration. The blood glucose
level of the treated animals reduced consistently from
6hours to a period of 24hours after administration. This
clearly shows that the 5% (w/v) aqueous extract of B.
ferruginea seem to act by stimulating the release of
insulin, as the alloxan treatment causes permanent
destruction of the β-cells.
The glucose tolerance of the rats (normal and
untreated diabetic) after oral glucose loading is shown in
Table 3.0. Administration of 5% (w/v) glucose solution
into control rats (normal) altered the blood glucose level
compared to the basal value. Administration of 5%
glucose solution following the administration of B.
ferruginea produced a decrease in blood glucose level
compared to the basal value (from 51.00 + 0.00 to
45.00 + 2.65).
In alloxan-induced diabetic untreated group,
administration of the glucose solution produced a
significant increase in the blood glucose level after
30mins. It can be assumed that this extract may stimulate
insulin secretion in a glucose-dependent manner
(MacDonald and Wheeler, 2003). On the other hand, the
hypoglycemic effect of the extract in the glucose fed rats
may be accounted in part, by an inhibition of intestinal
glucose absorption and the stimulation of the glucagon-
like peptide (GLP-1) which is also a glucose-dependent
insulin secretion (Goke et al, 1995).
The growth response of diabetic rats treated with
aqueous extract of B. ferruginea is shown in Table 4.0.
Treatment of alloxan-induced diabetic rats with the
extract for 24hrs resulted in weight gain compared with
the loss in weight of the control untreated at 6hrs. This
indicates the hypoglycemic effect of B. ferruginea since
diabetes is associated with weight loss. In alloxan-
induced diabetes, a massive reduction in insulin release
(due to the action of the alloxan which destroys the
insulin-secreting site β-cells of the islets of langerhans)
produces hyperglycemia (Dunn et al, 1943). This present
study clearly shows that the treatment with rats. The
possible mechanism(s) by which significantly that is at 6,
8,12 and 24 hours, blood action may be due to possible
pancreatic secretion of insulin from existing β-cells, to
enhance transport of blood glucose to peripheral tissues,
or reduced glucose absorption from the gastrointestinal
tract. It is therefore, hypothesized that B. ferruginea
contains one or more types of hypoglycemic principles.
CONCLUSION
The study suggests the hypoglycemic activity of B.
ferruginea in alloxan-induced diabetic rats and normal
rats, and supports the potential utility of B. ferruginea in
human healthcare for the treatment of diabetes mellitus.
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