Asian Journal of Research in Biochemistry
1(1): 1-17, 2017; Article no.AJRB.39152
Effects of Ethanol Leaf and Fruit Extracts of Kigelia
africana on Some Oxidative and Biochemical
Parameters of Alloxan -Induced Diabetic Rats
E. N. Uhuo1*, L. U. S. Ezeanyika2 and V. N. Ogugua2
1
Department of Chemical Sciences, Godfrey Okoye University, Enugu, Nigeria.
2
Department of Biochemistry, University of Nigeria, Nsukka, Nigeria.
Authors’ contributions
This work was carried out in collaboration between all authors. Author ENU designed the study,
performed the statistical analysis, wrote the protocol and first draft of the manuscript. Authors LUSE
and VNO managed the analyses of the study. Authors ENU and LUSE managed the literature
searches. All authors read and approved the final manuscript.
Article Information
DOI: 10.9734/AJRB/2017/v1i1366
Editor(s):
(1) Mohamed Fawzy Ramadan Hassanien, Professor, Biochemistry Department, Faculty of Agriculture, Zagazig University,
Zagazig, Egypt.
Reviewers:
(1) Samuel Ifedioranma Ogenyi, Nnamdi Azikiwe University, Nigeria.
(2) Nina Filip, Grigore T. Popa University of Medicine and Pharmacy, Romania.
(3) Keagile Bati, University of Botswana, Botswana.
(4) Kadiri Oseni, Obafemi Awolowo University, Nigeria.
Complete Peer review History: http://www.sciencedomain.org/review-history/23473
st
Original Research Article
Received 1 November 2017
Accepted 25th January 2018
th
Published 6 March 2018
ABSTRACT
Hyperglycaemia, a characteristic feature of diabetics mellitus leads to decreased antioxidant
defense and hence the development of oxidative stress, which is involved in the aetiology of
development of diabetic complications. This work was therefore aimed at evaluating the anti diabetic
and antioxidative potential of the plant. These evidences suggest that good glycemic control and/or
use of antioxidants may play an important role in the prevention of complications associated with
diabetes. Diabetes was induced with single Intra peritoneal injection of alloxan (160 mg/kg b.w)
dissolved in freshly prepared citrate buffer (pH 4.5). Oral administration of Kingelia africana (500
mg/kg b.wt) of methanol leaves and fruits extracts resulted in significant (p>0.05) decrease in the
blood glucose level, MDA, glycosylated haemoglobin, lipid profiles and liver maker enzymes with
corresponding increase in SOD activity, catalase activity, glutathione activity, serum protein
concentration, and Vit.C concentration. In conclusion, K. africana possessed antioxidative properties
evidenced by decrease blood glucose level and its effect on some oxidative parameters of diabetic
rats.
_____________________________________________________________________________________________________
*Corresponding author: E-mail: emmyuhuo@yahoo.com;
Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB.39152
Keywords: Diabetes; alloxan; antioxidant; Kingelia africana.
1. INTRODUCTION
changes in the structural and functional integrity
of sub-cellular organelles and may produce
effects that result in the various complications in
diabetic disease [11,12,13,14]. Recently, there
has been an upsurge of interest in the
therapeutic potentials of plants, as antioxidants in
reducing free radical-induced tissue injury.
Although several synthetic antioxidants are
commercially available, they are quite unsafe
and their toxicity is a problem of concern.
Globally, the estimated incidence of diabetes and
projection for year 2030, as given by
International Diabetes Federation is 350million
[1]. Currently available pharmacotherapies for
the treatment of diabetes mellitus include oral
hypoglycemic agents and insulin. However these
drugs do not restore normal glucose
homeostasis and they are not free from side
effects [2]. In view of the adverse effects
associated with the synthetic drugs and as plants
are safer, affordable and effective, conventional
antidiabetic plants can be explored [3]. Over 400
traditional plants have been reported for the
treatment of diabetes [4]. Furthermore, following
World Health Organization recommendations,
investigation of hypoglycemic agents from
medicinal plants has become more important [3].
Also, diabetes has been treated orally with
several medicinal plants based on folklore
medicine since ancient times.
A survey of literature revealed that there is no
experimental evidence of the antidiabetic effects
of Kigelia africana. Therefore, the present work
explores this and will, in addition, study its
potential effect on some oxidative and
biochemical parameters of alloxan-induced
diabetic rats.
2. MATERIALS AND METHODS
2.1 Plant Materials
The leave and fruit of Kingelia africana were
collected
from
Omor,
Aghamelu
Local
Government Area, Anambra State, Nigeria. The
plant was authenticated by the Department of
Plant Science and Biotechnology, University of
Nigeria Nsukka.
Kigelia
africana
(Lam.)
Benth
(Family:
Bignoniaceae) plant has many medicinal
properties due to the presence of numerous
secondary metabolites. These compounds
include iridiods, flavonoids, naphthoquinones,
volatile constituent, etc. [5,6,7 ].
2.2 Chemicals
Experimentally,
the
plant
has
shown
antibacterial,
antifungal,
antineoplastic,
analgesic,
anti-inflammatory,
antioxidant
properties [8]. Crude extracts of herbs and
spices and other materials rich in phenolics are
of increasing interest in the food industry
because they retard oxidative degradation of
lipids and thereby improve the quality and
nutritional value of food. Flavonoids are groups
of polyphenolic compounds with known
properties, which include free radical scavenging,
inhibition of hydrolytic and oxidative enzymes
and anti-inflammatory action [9].
These were analytical grade products and
include: ethanol methanol (BDH), ethylene
diamine tetraacetate (EDTA), hydrochloric acid
(BDH), sulphuric acid (BDH), Trichloloroacetic
acid (TCA), 2-thiobarbituric acid (TBA), Alloxan
Monohydrate (sigma-Aldrich, USA), 1-Chloro-2, 4
dinitrothiobenzene, glutathione peroxidase kit
(Randox Laboratories Limited, UK), Protein kit
(Randox
Company,
USA),
Superoxide
Dismutase kit (Randox Company, USA),
Glycosylated
haemoglobin
kit
(Randox
company,USA), Sorbitol kit, Lipid profile kit,
Glucose test (Life Scan Inc, California, USA).
An enhanced oxidative stress has been observed
in diabetic patients as indicated by increased free
radical production, lipid peroxidation and
diminished antioxidant status [10]. In diabetes
mellitus, alterations in the endogenous free
radical scavenging defence mechanisms may
lead to ineffective scavenging of reactive oxygen
species, resulting in oxidative damage and tissue
injury. Oxidative stress is currently suggested as
the mechanism underlying diabetes and diabetic
complications. Oxidative stress may cause
oxidative damage of cellular membranes and
2.3 Extraction of the Plant Material
The leaves and fruits of K. africana were air-dried
at room temperature for after which it was
grounded into powders using Rancilio Rocky
(Rigtig Kaffe A/S, Skanderborg, Denmark). A
quantity of 500 mg each of the powdered leaves
and fruits of K. fricana macerated in 1.5 litres of
Ethanol for 72h. The solution was filtered with
Whatman no 4 and concentred using rotary
evaporator (Model Modulyo 4K, England).
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Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB.39152
2.4 Animals
At the end of the experiment, rats were
starved for 12h and blood glucose levels
were determined. Blood samples were
received into clean dry centrifuge tubes and
use for the analysis of the parameters.
Male Wistar Albino rats between 12 to 14 weeks
of age, with an average weight of 108±5g, were
obtained from the Department of Zoology,
University of Nigeria Nsukka. They were housed
in the animal facilities of Department of Home
Science and Dietetics, University of Nigeria,
Nsukka for one week before starting the
experiment. The animals were allowed free
excess to a standard diet, water and maintained
under optimum conditions of temperature,
relative humidity and light period. (12h light/12h
dark).
2.7 Estimation of Biochemical parameters
All the chosen biochemical and oxidative
parameters were estimated using bio-diagnostic
kits and the procedures were strictly followed as
outlined in the manual guide.
2.8 Statistical Analysis
2.5 Induction of Diabetics
Results were reported as mean± SEM, where
appropriate. Both one-and two-way analysis of
variance (ANOVA) was used to analyse
the experimental data and Ducan multiple test
rage was used to compare the group means
obtained after each treatment with control
measurement. Significant value was taken at p <
0.05.
The rats were fasted (12h) prior to injection
of alloxan dissolved in cold citrate buffer (pH 4.5)
in a dose of 160 mg/kg intra-peritoneally. The
base line blood glucose level was determined
before the induction. On the fourth-day blood
samples were taken from the tail vein to measure
the blood glucose level using Accu-check
glucose meter (Roche, Germany). Rat with
blood glucose level of 200 mg/dl and above were
considered diabetic and used for the study [15].
3. RESULTS
3.1 Qualitative Phytochemical Composition of Ethanol Leaf and Fruit Extracts
of K. africana
The treatment was for a period of 4 weeks in
which the bloods obtained were used for
parameters analysis.
Table 1 Shows relative trace presence of
saponin
and
terpenoids
in
all
the
extract
samples.
In
the
same
vein,
hydrogen cyanide and steroid were found to
be present in trace concentrations. Relative
moderate amount of soluble carbohydrates
was found in all the extracts. Interestingly,
flavonoid was found in high concentration in the
extracts.
2.6 Experiment Begin
Thirty (30) male Wister albino rats with an
average weight of 108±5 g were classified into 6
groups (5 rats per group) and subjected to
treatment as follows.
Group i: Normal control rats.
3.2 Quantitative Phytochemical Composition
of Ethanol Leaf and Fruit Extracts of
K. africana
Group ii : Diabetics untreated rats.
Group iii: Diabetic rats treated 2.5 mg/kg bwt
glibenclamide
Table 2 shows the quantitative composition of
bioactive compounds present at various
concentrations. A significant increase of
flavonoid was recorded in ethanol fruit compared
with the leaf extracts. Trace concentration of
hydrogen cyanides was found in the extracts. All
the extracts contained moderate concentration of
alkaloid.
Group iv: Diabetics rats treated with 500 mg/kg
btw ethanol leaf extracts.
Group v: Diabetic rats treated with 500 mg/kg
btw ethanol fruit extracted.
Group vi: Diabetic rats treated with an equal
ratio of ethanol leaf and fruit extracts.
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Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB.39152
Table 1. Qualitative phytochemical composition of ethanol leaf and fruit extracts of K. africana.
Extract
Soluble carbohydrate
Ethanol leaf
Ethanol fruit
+
+
NB: +
Tannin
Alkaloid
+
++
+
++
Present in trace concentration, ++
Hydrogen cyanide
Saponin
Flavonoid
+
+
+
+
++
+++
Present in moderately high concentration, +++
Reducing
sugar
+
+
Steroid
+
+
GlycosideTTepenoid
++
++
Present in very high concentration
+
+
Table 2. Quantitative phytochemical composition leaf and fruit extracts of K. afrcana
Extract
Ethanol leaf
Ethanol fruit
Soluble
carbohydrate
(mg/100 g)
0.96±0.02
0.96±0.17
Tannin
(mg/100 g)
Alkaloid
(mg/100 g)
4.11±0.65
9.08±0.14
2.67±0.12
3.54±0.11
Hydrogen
cyanide
(mg/100 g)
0.03±0.001
0.95±0.02
Saponin
(mg/100 g)
Flavonoid
(mg/100 g)
0.52±0.02
0.56±0.03
2.32±0.04
3.63±0.02
Reducing
sugar
(mg/100 g)
50.85±3.36
26.95±5.14
Steroid
(mg/100 g)
Glycoside
(mg/100 g)
0.53±0.03
0.57±0.01
2.39±0.15
2.874±0.14
Table 3. Effect of ethanol extracts of leaves and fruits of K. africana on sugar level of diabetic rats
Treatment Groups
Group 1 (Normal Control)
Group 2 (Diabetic Untreated)
Group 3 (Standard Control)
Group 4 (Diabetic + Ethanol Leaf Extract)
Group 5 (Diabetic + Ethanol Fruit Extract)
Group 6 (Diabetic + Ethanol Leaf and Fruit Extract)
Before induction
ab
76.20±5.02
ab
67.40±3.50
66.40±3.91ab
ab
72.20±4.96
76.40±9.07ab
ab
64.60±3.20
Sugar Level (mg/dl)
72 Hours after induction
ab
78.80±2.71
ac*
558.40±14.01
321.00±115.16ab*
ab*
314.80±159.19
464.80±159.32ac*
ac*
479.60±142.28
After 21 days treatment
ab
75.40±4.22
ac*
405.40±15.96
241.20±116.79ab*
ab
184.40±54.50
273.20±93.59ab*
ab*
269.60±108.64
Results are expressed in mean ± SD; n = 5
Mean values with different letters as superscripts across the column compared with group 2 (diabetic untreated) are considered significant (p<0.05) while mean values with
asterisk (*) as superscripts across the row compared with the sugar level before the experiment are considered significant (p>0.05)
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3.3 Effects of Ethanol Extracts of Leaves
and Fruits of K. africana on Sugar
Level of Diabetic Rats
3.7 Effect of Ethanol Leaf and Fruit
Extract of K. africana on Glycosylated
Haemoglobin
Concentration
in
Alloxin-Induced Diabetic Rats
The sugar levels of rats before the experiment
in all groups were determined. Significant
(p<0.05) increased sugar level of induced
rats was observed compared with the sugar
level the rats before the experiment as shown
in Table 3. Reversibly, sugar level of rats
after
21
days
treatment
reduced
significantly (p<0.05) compared the level of
sugar at 72 hours after induction and before
induction.
The mean HbA1c level decreased significantly
(p<0.05) in all the test groups compared with the
HbA1c level of untreated diabetics rats (Group
2).Change in HbA1c level was observed in
Group 6 rats treated with a combination of leaf
and fruit extract in ratio of 1:1 compared with
Group 2 rats untreated. A significant increase
(p<0.05) HbA1c level was recorded in all the test
groups against the normal control rats (Fig.3).
Group 6 (diabetic+ ethanol leaf and fruit extracts,
ratio 1:1) demonstrated a non-significant
(p>0.05) reduction of HA1c concentration
compared with groups 4 and 5 rats orally fed with
single plant extract (Fig. 3).
3.4 Body Weight of Diabetic Rats
Treated with Ethanol Extracts of
Leaves and Fruits of K. africana
before and after Experiment
3.8 Effects of Ethanol Extracts of Leaf
and Fruit of K. africana on
Malondialdehyde(MDA) Concentration
in Alloxan-Induced Diabetic Rats
Significant (p<0.05) increased in the body weight
of test groups compared with diabetic rats after
treatment was observed. Conversely, nonsignificant (p>0.05) decrease was observed in
the body weights of the animals in other groups 6
after the experiment compared with the body
weights of the animals before the experiment of
the control group. (Table 4)
Lipid peroxidation measured as malondialdehyde
(MDA) observed significantly increase (p<0.5) in
all the test groups compared with untreated
control as shown in Fig.4. A significant decrease
of MDA concentration was recorded in group 6
treated with the combination of the plant extract
compared with the groups administered with
single extract (Groups 4 and 5). Similarly, a
significant
decrease
(p<0.05)
of
MDA
concentration was observed in the test groups
compared with MDA concentration of untreated
diabetic group.
3.5 Effects of Ethanol Leaf and Fruit
Extracts of K. africana on Sorbitol
Concentration in Alloxan-Induced
Diabetic Rats
Sorbitol concentration in all the test groups
decreased significantly (p<0.05) compared with
the untreated diabetic animals (Group 2). A
significant (p<0.05) reduction of sorbitol
concentration was recorded in groups 6 treated
with a combination of the leaf and fruit extracts of
K.africana compared with the diabetic untreated
rats (Fig. 1).
3.9 Effects of Ethanol Leaf and Fruit
Extracts of K. africana on Vitamin C
Concentration in Alloxan-Induced
Diabetic Rats
There was a general decrease in vitamin C
concentration in all the test groups and the
untreated diabetic group compared with the
vitamin concentration of normal control rats
(Group 1). There was statistically significant
increase (p<0.05) of vitamin C concentration in
group 6 rats treated with a combination of
ethanol leaf and fruit extracts compared with
other test groups. The diabetic rats administered
2.5 mg/kg b.wt of glibenclamide demonstrated an
increased (p<0.05) vitamin c level compared with
the vitamin C concentration of rats in Group 2
(diabetic untreated rates), see Fig.5
3.6 Effect of Ethanol Leaf and Fruit
Extract of K. africana on Total Protein
Concentration in Alloxan-Induced
Diabetic Rats
Fig. 2 reveals observable significant increased
(p>0.05) of total protein in all test groups
compared with the positive control rats (Group
2). Total protein concentrations in groups 6 fed
with a combination of the leaf and fruit extract
showed significant increase (p<0.05) compared
with other test groups.
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Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB. 39152
3.10 Effects of Ethanol Leaf and Fruit
Extracts of K. africana on Catalase
Activity in Alloxan-Induced Diabetic
Rats
(p<0.05) increase in SOD activities
of all
test groups compared with
the untreated
diabetic rats (Group 2) as shown in Fig. 7.
Superoxide dismutase activities of the test
groups (Group 6) administered with the
combination of the extracts was significantly
increased (p<0.05) compared with other test
groups treated with the single extracts (Groups 4
and 5). The same observation was noted in the
test treated with the standard drug. However, the
activities of SOD in the diabetic rat administered
with 2.5 mg /kg b.wt of glibenclamide increased
significantly (p<0.05) as against all the test
groups.
Across the test groups was recorded a
statistically significant increase (p<0.05) catalase
activity (Fig.6) compared with the untreated
diabetic rats (positive control; Group 2). Similarly,
a significant increase (p<0.05) of catalase activity
was observed in the diabetic rats treated with
reference drug (glibenclamide) in comparison
with the catalase activity of all the test groups. In
the same pattern, Group 6, ethanol leaf + fruit
extracts demonstrated a non significant increase
(p>0.05) of catalase activity compared with other
test groups (Groups 4 and 5) administered with a
single plant extract.
3.12 Effects of Ethanol Leaf and Fruit
Extracts
of
K.
africana
on
Percentage Inhibition of SOD
Activity in Alloxan-Induced Diabetic
Rats
3.11 Effects of Ethanol Leaf and Fruit
Extracts
of
K.
africana
on
Superoxide
Dismutase
(SOD)
Activity in Alloxan-Induced Diabetic
Rats
Fig.8 demonstrates statistically significant
decrease (p<0.05) of percentage inhibition of
SOD activity in the test groups compared with
the normal control group. A significant reduction
(p<0.05) of percentage inhibition of SOD activity
occurred in the diabetic untreated rats (group 2)
compared with the percentage inhibition of SOD
activity in normal control. Diabetic 6 treated with
The activities of superoxide dismutase (SOD)
reduced significantly (p<0.05) in all the test
groups compared with the normal control
(Group 1).There were statistically significant
Fig. 1. Effect of ethanol extracts of leaf and fruit of K. africana on sorbitol concentration in
alloxan-induced diabetic rats
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Table 4. Body weights of diabetic rats treated with ethanol extracts of leaves and fruits of K
.africana before and after experiment
Treatment Groups
Body Weight (g)
Before Experiment
After Experiment
a
b
92.59±5.87
130.36±17.83
a
a
173.66±12.24
156.16±13.14
a
107.34±18.41a
94.58±5.80
a
125.98±14.59b
103.94±8.30
a
a
119.83±40.91
127.94±37.44
a
a
95.12±4.09
86.71±9.77
Group 1 (Normal Control)
Group 2 (Diabetic Untreated)
Group 3 (Standard Control)
Group 4 (Diabetic + Ethanol Leaf Extract)
Group 5 (Diabetic + Ethanol Fruit Extract)
Group 6 (Diabetic + Ethanol Leaf and Fruit
Extract)
Results are expressed in mean ± SD; n = 5
Mean values with different letters as superscripts across the row are considered significant (p<0.05)
Fig. 2. Effect of ethanol extracts of leaf and fruit of K. africana on total protein concentration in
alloxan-induced diabetic rats
3.13 Effects of Ethanol Leaf and Fruit
Extract of Kigelia africana on
Glutathione Peroxidase Activity in
Alloxan-Induced Diabetic Rats
a combination of leaf and fruit extracts recorded
a significantly (p>0.05) increase of percentage
inhibition of SOD activity compared with groups 4
and 5 administered monotherapically with leaf
and fruit extracts of K. africana. Conversely,
group 6 treated with ethanol leaf extracts showed
significant increase (p<0.05) of percentage
inhibition of SOD activity as against groups 4, 7
and 8 of the same treatment pattern.
Furthermore, non-significant reduction (p>0.05)
of percentage inhibition was observed in
diabetic administered the n-hexane leaf and fruit
extracts compared with the diabetic rats treated
with 2.5 mg/kg body weight of glibenclamide
(Group 3).
Fig. 9 represents activity of glutathione
peroxidase (GPx) which increased significantly
(p<0.05) in all the test groups treated with both
single and combination of the leaf and fruit of K.
africana extract in comparison with the GPx
activity of the rats in group 1 (normal control
rats). The combination therapy in group 6
demonstrated significant increase (p<0.05) of
GPx activity compared with groups 4 and 5 test
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Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB. 39152
groups treated with a single plant extract
(monotherapy).In the same vein test groups 6
treated with combined leaf and fruit extracts
increased
in
GPx
activity
significantly
(p<0.05) relative to group 3 treated with the
standard drug.
Fig. 3. Effect of ethanol extracts of leaf and fruit of K. africana on glycosylated haemoglobin
concentration in alloxan-induced diabetic rats
Fig. 4. Effects of ethanol extracts of leaf and fruit of K. africana on malondialdehyde
concentration in alloxan-induced diabetic rats
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Fig. 5. Effects of ethanol extracts of leaf and fruit of K. africana on vitamin C concentration in
alloxan-induced diabetic rats
Fig. 6. Effects of ethanol extracts of leaf and fruit of K. africana on catalase activity in
alloxan-induced diabetic rats
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Fig. 7. Effects of ethanol extracts of leaf and fruit of K. africana on superoxide dismutase in
alloxan – induced diabetic rats
Fig. 8. Effects of ethanol extracts of leaf and fruit of K. africana on superoxide dismutase
percentage inhibition in alloxan-induced diabetic rats
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3.14 Effects of Ethanol Leaf and Fruit
Extract of K. africana on Total
Cholesterol
Concentration
in
Alloxan-Induced Diabetic Rats
extracts of leaf and fruit of K. africana as shown
in Fig. 11 compared with the HDL concentration
of normal control rats ( group 1). Conversely, the
HDL concentration of rats in test groups 6
administered with a combination of ethanol leaf
and fruit of equal ratio increased, though not
significant (p>0.05) compared with the HDL
concentration of rats in group 3 treated with the
standard drug (2.5 mg/kg body weight). Similarly,
a significant decrease (p<0.05) of HDL
concentration was obtained in group 6 treated
with a combination of the two parts of the plant
compared with the diabetic untreated rats (Fig.
11).
Fig.10 shows relative increase in the total
cholesterol concentration in diabetic test groups
4, 5 and 6 compared with the total cholesterol
concentration of normal control in group 1, the
increase was found to be significant (p< 0.05). A
significant (p<0.05) decrease was noted in the
diabetic rats administered with the standard drug
compared with the untreated diabetic rats (group
2). Similar trend of result was observed in total
cholesterol concentration of group 6 treated with
a combination of the extracts compared with the
total cholesterol concentration in diabetic
untreated
3.16 Effects of Ethanol Leaf and Fruit
Extracts of africana on Low Density
Lipoprotein
Concentration
in
Alloxan-Induced Diabetic Rats
3.15 Effects of Ethanol Leaf and Fruit
Extract of K. africana High Density
Lipoprotein
Concentration
in
Alloxan-Induced Diabetic Rats
Fig. 12 shows significant increase (p<0.05) in the
concentration of low-density lipoprotein (LDL) in
test groups 2 & 4 compared with the
concentration of low- density lipoprotein of the
control rats (group 1). Non-significant (p>0.05)
variation of low-density lipoprotein (LDL)
concentration across the test groups 4 & 5
A significant reduction (p<0.05) of high-density
lipoprotein (HDL) cholesterol was noted in
groups 4 and5 treated with different single
Fig. 9. Effects of ethanol extracts of leaf and fruit of K. africana on glutathione peroxidise
activities in alloxan-induced diabetic rats
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(diabetic +single plant extract) compared the
LDL concentration of rats in groups 6 treated with
a combination of K. africana leaf and fruit
extracts. Invariably, significant (p<0.05) decrease
of LDL concentration was observed in all, except
Group 4 as against diabetic rats untreated
(Group 2).
(standard treatment) demonstrated observable
significant (p>0.05) changes in comparison with
other test groups (4, 5 and 6 ).
4. DISCUSSION
This study evaluated the antidiabetic and
antioxidative properties of Kigelia africana in
alloxan-induced diabetic rats. From the results
obtained; untreated diabetic rats had much
higher blood glucose level than that of the normal
control. Changes in blood glucose levels reflect
abnormalities in ß- cells structure and function.
Alloxan causes glucose oxidation and reduction
in insulin release by the destructions of ß- cells of
the islets of Langerhans [16]. Administration of K.
africana ethanol leaf and fruit extracts restored
glucose level in alloxan- induced diabetic rats
near the normal level. Glibenclamide was used
as a standard drug to compare the activity of K.
africana extract in reference to blood glucose
reduction. The results revealed that the extracts
in a dose of 500 mg/kg body weight significantly
st
(P<0.05) decreased blood glucose level at 21
day indicating that the extracts possessed extra
pancreatic
hypoglycemic
activities.
The
3.17 Effects of Ethanol Leaf and Fruit
Extracts
of
K.
africana
on
Triacylglycerol (TAG) Concentration
in Alloxan-Induced Diabetic Rats
Triacylglycerol (TAG) concentration decreased
significantly (p<0.05) in Groups 4 to Group 6)
orally fed K. africana extracts compared with the
TAG concentration of rats (Group 2).
Furthermore, a significant increase (P<0.05) of
TAG concentration in group 4 and 5 was
observed in comparison with normal control rats
(Group 1). However, a non-significant (p>0.05)
decrease of TAG concentration in group 6
administered with a combination of leaf and fruit
extracts of K. africana was noticed compared
with groups 4 and 5 treated with single extract of
the plant. Also as shown in Fig. 13, Group 3
Fig. 10. Effects of ethanol extracts of leaf and fruit of K. africana on total cholesterol
concentration in alloxan-induced diabetic rats.
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Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB. 39152
Fig. 11. Effects of ethanol extracts of leaf and fruit of K. africana on high density lipoprotein
concentration in alloxan-induced diabetic rats
Fig. 12. Effects of ethanol extracts of leaf and fruit of K. africana on low density lipoprotein
concentration in alloxan-induced diabetic rats
comparable effect of the extract (500 mg/kg) with
glibenclamide (2.5 mg/kg) may suggest a similar
mode of action since the main mechanism of the
action of glibenclamide is the stimulation of
13
Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB. 39152
insulin release and the inhibition of glucagon
secretion. It has been described that
glibenclamide is effective in moderate diabetic
state and ineffective in severe diabetic animals
where pancreatic ß- cells are totally destroyed
[17]. The possible mechanism by which the plant
extract brings about its hypoglycemic action may
be by potentiating the insulin effect thereby
increase pancreatic secretion of insulin from ßcells [18]. The findings also suggest that K.
africana leaf and fruit many generate ß- cells and
have protective effect on ß- cells from glucose
toxicity.
reductase by the extracts. Sorbitol is a product of
polyol pathway and is a feature of diabetic
complications. It could be suggested that some
of the active constituents of K. africana extracts
inhibit the activity of aldose reductase; the major
enzyme in the polyol pathway.
This study further revealed significant reduction
(P<0.05) of sorbitol concentration in groups 6
rats treated with the combination of leaf and fruit
extracts relative to animals treated with the
reference drug (2.5 mg of glibenclamde). This is
in line with the fact that synthetic drugs do not
restore normal glucose homeostasis and are not
free from side effect [2].
In general, there is little biological knowledge on
the specific modes of action of plants in the
treatment of diabetics, but most of the plants
have been found to contain substances like
glycosides, alkaloids, terpernoids, and flavonoid
that are frequently implicated as having
antidiabetic effect [19]. This was also buttressed
by the results of the phytochemistry of K.
africana which revealed high percentage of
flavonoid, glycoside, alkaloid, terpernoid that are
frequently implicated as having an antidiabetic
effect. These plant constituents can lower blood
glucose level.
A significant (p<0.05) increase in glycosylated
haemoglobin level in the diabetic rats untreated
with reference to the normal control animals
(group 1) was recorded in this study. The
increase was in accordance with the report of
several other researchers [20,21,22].
The
increased glycosylation may be as a result of
diabetic complications caused by oxidative
stress.
Generally,
decreased
in glycolhaemoglobin level was observed in diabetic rats
treated with K. africana extracts as against
diabetic rats not treated. The decrease in glycolhaemoglobin level could be attributed to the
extracts’ ability to reduce glucose level in the
blood stream.
Sorbitol concentration significantly decreased
(P<0.05) across all the test animals in reference
to diabetic untreated rats. This reduction is
probably due to the reduction of sorbitol
Fig. 13. Effects of ethanol extracts of leaf and fruit of K. africana on triacylglycerol
concentration in alloxan-induced diabetic rats
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Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB. 39152
High concentration of MDA in diabetic untreated
established oxidative stress status in the
animals. In hyperglycemic condition, glucose is
one of the major sources of free radicals. Lipid
peroxidation measured as malondialdehyde
(MDA) significantly (p<0.05) decreased in all the
test groups compared with diabetic rats
untreated (group 2). Groups 6 treated with a
combination of leaf and fruit extracts showed
significant
(p<0.05)
decrease
in
MDA
concentration as against groups 4-5 treated with
single extract. Reduction in the lipid peroxidation
index in treatment groups indicates the ability of
the extracts to stem down the oxidative stress by
mopping up free radical that lead to lipid
breakdown. The bioactive constituents of the
extracts such as flavonoids, alkaloids as
revealed by photochemistry results could be
implicated in free radical scavenging properties
of the extracts.
contradictory; both increase and decrease of
antioxidant activity have been reported [25,26,]
The report on the SOD activity in diabetic state is
controversial with some authors reporting no
change in SOD activity [27] while others reported
increased [28,29] and decreased SOD activity
[28]. In the present study, significant (P<0.05)
decreases in the activities of SOD, CAT and GPx
were recorded in diabetic rats not treated
compared with the normal control group. An
observed significant (p<0.05) increases of these
antioxidant enzymes were recorded in group 6
treated with a combination of two parts of
K.africana extracts as against groups 4-5 with
monotherpeutic administration of leaf and fruit
extracts of the same. Reduction of the
antioxidant enzymes activities were observed in
diabetic rats not treated with reference to test
rats treated with the standard drug. This is in line
with the report that products of membrane lipid
peroxidation and other oxidants like H2O2 may
react with superoxide dismutase resulting in
oxidative modification thereby causing loss of
enzyme activity in diabetic condition [28]. The
result also concords with the reports that the
relatively low expression of antioxidant enzymes
such as catalase and superoxide dismutase,
pancreatic ß-cells may be vulnerable to reactive
oxygen species (ROS) attack when the system is
under oxidative stress situation [30,31. Similarly,
elevated levels of free radicals, due to the
insufficiency of the antioxidant defence system,
may lead to disruption of cellular functions,
oxidative damages to protein, DNA, membranes
and enhance their susceptibility to lipid per
oxidation [10] under uncontrolled diabetic
condition. Also, hyperglycemia leads to glycation
and inactivation of superoxide dismutase thus
attributing to its decrease. In the study, the
animals treated with K. africana extracts showed
an increase in the activity of antioxidant enzymes
as against untreated diabetic rats (group 2) and
this unveiled the extracts’ potential in mopping up
or scavenging free radicals generated under
oxidative stress- mediated diabetes. The
bioactive compound, favonoids may be
implicated in the scavenging activity of the plant
extracts in oxidative condition.
A significantly increase (p<0.05) in serum total
protein was recorded in all the test groups
treated with the plant extracts in comparison with
the diabetic untreated rats. The decrease in
serum total protein was observed in untreated
diabetic rats with reference to test groups both
single and combination of the plant extracts. This
is in tandem with the proximate composition of
the plant that revealed approximate 13% protein.
The most commonly observed lipid abnormalities
in diabetes are hypertriglyceridemia and
hypercholesterolemia [23] and these contribute
to coronary artery diseases. This lends credence
to the significant (P<0.05) increase of total
cholesterol, triacylglycerol and low-density
lipoprotein in the diabetic rats used in this study.
K. africana treated rats showed a reduction in
these lipids which buttressed the hypolipidemic
effects of the plant. The hypolipidemic effect may
be due to inhibition of fatty acid synthesis [24]. It
could also be attributed to the increase in the
reverse cholesterol transport pathway and
decreased cholesterol concentration in the
intestine due to α- glycosidase inhibition.
Administration of a combination of leaf and fruit
extracts of K. africana resulted in a significant
(p<0.05) decrease in lipid parameters when
compared with the diabetic control animals
(group-2). It can be further stated that K. africana
plant extracts have the potential to correct the
lipid
abnormalities,
thus
delaying
lipid
peroxidation in diabetic condition.
5. CONCLUSION
From the results, it can be concluded that 500
mg of K .africana extracts possess antihyperglycemic effect via α-glycosidase inhibition.
Significant reduction of glycol-haemoglobin level
and sorbitol concentration in all the diabetic
The reports on the status of antioxidants and
antioxidant enzymes in diabetic state are very
15
Uhuo et al.; AJRB, 1(1): 1-17, 2017; Article no.AJRB. 39152
groups treated with either the extracts or
reference drug compared with the control groups.
The extracts were found to have lipid lowering
effects through reduction of total cholesterol,
triacyglycerol and low density lipoprotein. K.
africana increased high-density lipoprotein level
probably by decreasing
reverse cholesterol
transport pathway.
10.
11.
12.
COMPETING INTERESTS
Authors have
interests exist.
declared
that
no
competing
13.
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