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Nigerian Journal of Physiological Sciences
Physiological Society of Nigeria
ISSN: 0794-859X
Vol. 23, Num. 1-2, 2008, pp. 37-40
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Nigerian
Journal Of Physiological Sciences, Vol. 23, No. 1-2, 2008, pp. 37-40
Hypoglycaemic And
Hypolipidaemic Effects Of The Aqueous Leaf Extract Of Murraya koenigii In Normal And Alloxan Diabetic Rats
H. A.Lawal1,M.
K. Atiku1, D. G. Khelpai 2 And N. N. Wannang 2.
1Department of
Biochemistry, Bayero University, P.M.B. 3011, Kano, Nigeria
2Department of
Pharmacology, Faculty of Medicine, Bayero University, P.M.B. 3011, Kano, Nigeria
Code Number: np08009
Summary
The hypoglycaemic effect of aqueous
leaf extract of Murraya koenigii was studied in normal and alloxan-
induced diabetic rats. The extract was administered orally at 100 mg/Kg, 150
mg/Kg and 200 mg/Kg bodyweight each to respective groups of animals (Groups I,
II and III) for seven days. Group IV received normal saline and served as
control for the normal rats. For the alloxan-induced diabetic rats, the same
dosage pattern was administered to three groups of rats for seven days (Groups
V, VI and VII) while group VIII which received normal saline served as control.
At the various dose levels administered, the glucose lowering effect was more pronounced
in the alloxan-diabetic rats than in control rats. When compared with
chlorpropamide, the glucose lowering effect of aqueous extract of Murraya
koenigii was significantly (p <0.05) lower at the dose levels administered
in both normal and alloxan-diabetic rats.
Key Words: Murraya
koenigii, Hypoglycaemia, diabetes mellitus, plasma glucose
Introduction
Diabetes mellitus is a metabolic disorder of multiple
aetiology characterized by chronic hyperglycaemia with disturbances of carbohydrate,
fat and protein metabolism resulting from defects in insulin secretion, insulin
action or both. Management of this disease may include lifestyle modifications,
diet, exercise, long term use of oral hypoglycaemic agents or insulin
therapy.
Since ancient times, plants have been an exemplary
source of medicine. The search for plants with hypoglycaemic property is an
area that draws attention of research workers globally. Grover et al. (2002)
reviewed 45 of such plants and their products that have been mentioned/used in
the Indian traditional system of medicine. Literature reports have indicated
that the use of Momordica foetida (Olaniyi, 1980), Disocorea
dumentorum (Iwu et al., 1990a), Garcina kola (Iwu et al., 1990b),
etc as antidiabetic agents in Nigeria.
Murraya koengii is a small deciduous tree with very pungent aromatic leaves (curry
leaf) belonging to the family Rutaceae of trees. The family includes plants
throughout tropical zones on most continents and includes approximately 1500
genera and 1500 species. In Kano State, curry leaf is used traditionally as a
stimulant, anti-dysenteric and for management of diabetes mellitus. Even
though, literature reports elsewhere (Khan et al., 1995) indicate that Murraya
koengii possess hypoglycaemic property, the plant has not been subjected to
scientific investigation (in the context in which it is used) in Kano State. Therefore, this work is aimed at investigating the hypoglycaemic effect of
aqueous extract of Murraya keonigii and its effect on serum lipid levels
in normal and alloxan diabetic rats.
Materials
and Methods
Plants
materials/preparation of the extract
Fresh leaves of the plant (Murraya koenigii)
were obtained locally from a farmer in Kano metropolis. The leaf was identified
by a staff of the Botany Unit, Bayero University, Kano. Aqueous leaf extract
was prepared as described by Sofowora (1984). The fresh leaves were oven-dried
at 45°C for 3 days, ground into power and 20g soaked in 300ml of
distilled water overnight at room temperature. The filtrate obtained was
evaporated to constant weight in a hot-air oven at 45°C for 4 days
and the yield of the extract was approximately 60%. The extract was weighed
(2g) and reconstituted in appropriate volume of distilled water before
administration to the rats.
Animals
Adult male wistar rats weighing between 150- 200g,
obtained from the National Veterinary Research Institute (NVRI), Vom, Plateau
state, Nigeria were used. The animals were allowed free access to food and
water. Growers mash was used to feed the animals throughout the study period.
The rats were divided into eight groups of five rats per group. Groups I, II,
III were administered aqueous leaf extract of Murraya koenigii at dose
levels of 100mg/kg, 150mg/kg and 200mg/kg body weight respectively. Group IV
received normal saline only and served as control for the normal rats.
Experimental diabetes was induced in the
hyperglycaemic group with alloxan- (sigma) administered intraperitoneally at a
dose of 100mg/kg. Rats were left for a period of four days prior to
commencement of extract administration. Groups V, VI and VII were administered
orally aqueous leaf extract of M. koenigii at dose levels of 100 mg/Kg,
150 mg/Kg and 200 mg/Kg bodyweight respectively. Group VIII received normal
saline only and served as control for the alloxan induced rats.
Blood
collection and Biochemical Analysis
At the end of seven days period of extract
administration, the rats were sacrificed. Blood samples were collected from the
heart region directly into anticoagulant bottles and later plasma was collected
after centrifugation. DIALAB® Diagnostic reagent kit was used to estimate
plasma glucose concentration. Plasma triglyceride concentration was also
determined using DIALAB® diagnostic reagent kit, while total cholesterol
concentration was estimated using RANDOX® kit (catalogue No: CH 200). HDL
cholesterol was estimated in the supernatant left after precipitating very low
density lipoproteins (VLDL) and low density lipoproteins (LDL) using magnesium
chloride/phosphotungstic acid, was used to estimate plasma high density
lipoprotein cholesterol (HDL CH) using RANDOX® kit (catalogue No: CH 200).
LDL Cholesterol was calculated by Friedwalds formula (Friedwald et al., 1972).
Acute
Toxicity
Various doses (80 mg/Kg, 400 mg/Kg and 2000 mg/Kg) of
aqueous leaf extract of M. koenigii were administered intraperitoneally
to respective groups of rats. A control group were administered
intraperitoneally normal saline. Rats were observed closely for toxic symptoms
and behavioural changes for the first 2 hours of administration and mortality
recorded within 24 hours.
Statistical Analysis
Fischers
t test was used for statistical analysis.
Table
1: Effect of aqueous leaf extract of Murraya koenigii on serum glucose and
serum lipids in normal rats after 7 days of administration
Animals |
Dose (mg/Kg bodyweight) |
Glucose (mmol/l) |
TG (mmol/l)
|
TC (mmol/l)
|
HDL CH (mmol/) |
LDL CH (mmol/e)
|
Group
I
n
=5
|
100
|
4.19 ± 0.13
|
*1.89 ± 0.43
|
2.37 ± 0.22
|
0.54 ± 0.10
|
1.46 ± 0.09
|
Group
II
n
=5
|
150
|
*3.80 ± 0.13
|
2.14 ± 0.43
|
1.73 ± 1.08
|
0.46 ±0.35
|
0.84 ±0.66
|
Group
III
n
=5
|
200
|
*3.27 ± 0.13
|
3.22 ± 0.97
|
4.31 ± 0.78
|
*1.19 ± 0.10
|
2.48 ±0.51
|
Group
IV
n
=5
|
-
|
4.45 ±0.26
|
3.39 ± 0.38
|
3.23 ± 1.94
|
0.73 ± 0.33
|
1.82 ± 1.54
|
Results
are mean ± standard deviation, n = number of animals. *significantly
different from controls at p < 0.05
Table 2: Effect of aqueous leaf
extract of Murraya koenigii on serum glucose and serum lipids in alloxan
induced rats after 7 days of administration
Animals
|
Dose (mg/Kg bodyweight)
|
Glucose (mmol/l)
|
TG (mmol/l)
|
TC (mmol/l)
|
HDL CH (mmol/l)
|
LDL CH (mmol/e)
|
Group
V
n
=5
|
100
|
*3.27 ± 0.12
|
4.89 ± 0.38
|
4.10 ± 0.94
|
0.61 ± 0.30
|
2.50 ± 0.75
|
Group
VI
n
=5
|
150
|
*2.75 ± 0.23
|
4.14 ± 0.50
|
5.60 ± 0.94
|
0.81 ± 0.30
|
3.97 ± 0.59
|
Group
VII
n
=5
|
200
|
*2.23 ± 0.13
|
2.64 ± 0.14
|
4.31 ± 1.69
|
0.73 ± 0.30
|
3.05 ± 1.36
|
Group
VIII
n
=5
|
-
|
4.32 ± 0.23
|
4.18 ± 0.58
|
5.17 ± 1.12
|
0.92 ± 0.12
|
3.63 ± 1.45
|
Results
are mean ± standard deviation, n = number of animals. *significantly
different from controls at p < 0.05
Table 3: Comparison of the glucose
lowering effect of aqueous leaf extract of Murraya koenigii between normal and
alloxan diabetic rats
Animals |
Group I
N
|
Group V
ALD
|
Group II
N
|
Group VI
ALD
|
Group III
N
|
Group VII
ALD
|
Glucose
(mMol/L) |
4.19* ± 0.13 |
3.27* ± 0.12 |
3.80* ± 0.13 |
2.75* ± 0.23 |
3.27* ± 0.13 |
2.23 ± 0.13 |
Results
are mean ± standard deviation, n = number of animals. *significantly
different at p < 0.05 N = normal, ALD = alloxan diabetic
Results
and Discussion
Table 1 presents the effect of aqueous extract of M.
keonigii on plasma glucose and serum lipids in normal rats after seven days
of administration. Plasma glucose levels decreased in a dose dependent manner
from Group I to Group III and the levels were lower than the level in the
control group (Group IV). The differences in plasma glucose levels between
Groups II, III and Group IV (control) were statistically significant (P <0.05).
The difference in the plasma triglyceride level between Group I and Group IV
was also statistically significant (P < 0.05). Plasma TC, HDL CH, and LDL
CH levels did not differ in any clear trend between the groups.
In alloxan diabetic rats, the aqueous extract of M.
keonigii had the same effect on plasma glucose levels as in normal rats
(Table 2). Plasma glucose levels decreased significant (P <0.05) between
Group V, VI, VII and Group VIII (control). Plasma triglyceride differed
significantly (P < 0.05) between Group VII and Group VIII (control). At the
dose levels administered, the glucose lowering effect of aqueous extract of Murraya
keonigii was significantly higher (P <0.05) in alloxan diabetic rats
than in normal rats (Table 3). No mortality was recorded during acute toxicity
study up to a dose of 2000mg/Kg (Table 4).
Table
4: Data on mortality in rats after acute treatment with aqueous leaf extract of
M. koenigii
Dose (mg/Kg bodyweight) |
No. of rats |
Mortality |
Control |
4 |
0 |
80 |
4 |
0 |
400 |
4 |
0 |
200 |
4 |
0 |
The findings of this study suggest that Murraya
keonigii aqueous leaf extract possesses hypoglycaemic activity in normal
and alloxan induced diabetic rats. This result agrees with earlier reports
(Khan et al., 1995; Grover et al., 2002 and Kesari et al., 2005).
However, this result contradicts the report of Adebayo et al. (2004)
which refuted the antidiabetic ethnomedical claim of M. keonigii. Although,
the extract showed antidiabetic properties, its activity was less than that of
chlorpropamide at all doses administered. Therefore, the plant extract cannot
be used as a substitute for conventional antidiabetic drugs.
It has been suggested that M.
koenigii acts by decreasing glycogenesis and gluconeogenesis (Khan et
al., 1995). However, characterization of the active principle responsible
for the hypoglycaemic activity of M. keonigii has not yet been done. As
no mortality was recorded within 24 hours during the acute toxicity test, LD50 could not be calculated. The non toxic effect of the aqueous leaf extract of M.
koenigii (Table 4) lend support to the widespread use of the plant as a
spice for food flavouring. It is also interesting to note that the glucose
lowering effect of aqueous leaf extract of M. koenigii was higher in
alloxan induced diabetic animals than in normoglycaemic animals (Table 3).
This finding may form a basis for the inclusion of M. koenigii as a
spice in the dietary management of diabetes mellitus. However, this postulate
is open for further investigation.
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© Physiological Society Of Nigeria, 2008.
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