Anti-Ulcerogenic and Membrane
Stabilization Effect of Ethanol Extract of Coconut (Cocos nucifera)
*Anosike Chioma Assumpta, Obidoa Onyechi, Nwodo Okwesilieze Fredrick C. and
Joshua Parker Elijah.
Department of
Biochemistry, Faculty of Biological Sciences, University of Nigeria, Nsukka, Enugu State, Nigeria
ABSTRACT:
The
effects of the ethanol extract of coconut on indomethacin
– induced gastric ulcer in Wistar rats and on Hypotonicity induced haemolysis
of human red blood cells were studied. Ulcer was induced in the rats by post
oral (p.o.) administration of indomethacin
(50mg/kg) using standard procedures. The percentage ulcer inhibition was taken
as the measure of the cytoprotection offered by the
coconut extract. The extracts reduced the gastric erosions induced by indomethacin in a dose dependent manner with 100mg/kg dose
having an ulcer inhibition of 65.4%; 200mg/kg gave 67.9% inhibition while
400mg/kg caused a 70.1% reduction in the ulcerations formed. These results were
comparable to the 91% reduction recorded for ranitidine, the standard
anti-ulcer drug. The effect of the coconut extract on haemolysis
induced by distilled water was evaluated by incubating various concentrations
of the extract with red blood cells and distilled water. The effect of the
standard anti-inflammatory drug, indomethacin was
determined as a positive control. Changes in absorbance were used to assess the
extent of haemolysis, hence membrane stabilization.
From the results obtained, coconut extract gave a dose dependent reduction in
the haemolysis induced by distilled water. This
suggests that the extract has a stabilizing effect on lysosomal
membranes.
KEYWORDS: Coconut extract, gastric erosions, cytoprotection, RBCs haemolysis,
distilled water.
INTRODUCTION:
The
coconut palm (Cocus nucifera L.)
locally referred to as kwa kwa
in Hausa, Aku oyibo in Ibo,
Agbon in Yoruba and Isip oyon in Efik, is a member of the
family Arecaceae (palm family). It is the only specie
of the genus cocos which grows throughout the
tropical countries including
Its
water (coconut water) is used as an intravenous fluid to counteract the effects
of drug overdose, poisoning and adverse drug reactions[3,
1]. Coconut water is also a source of quick energy,
boosts energy and endurance. It is used in place of dextrose\glucose in medical
emergencies. During World War II, young coconut water was used as an emergency
room glucose supply in the absence of sterile glucose1. Coconut water also relives the symptoms associated with Crohn’s disease, an illness in which the intestines are
infected4. It has been reported to be antihelmintic,
antidotal, antiseptic, astringent, bactericidal, diuretic, purgative, vermifuge, stomachic and
supportive5.
Indigenous people of tropical countries use young
coconut juice in the treatment of stomach upsets, diarrhea and dysentery,
ulcerative colitis and stomach ulcers5.
The
most abundant nutrient in the coconut is fat, which makes up more than a third
of its mature weight. The lauric acid content
of coconut endows it with antimicrobial properties. As such, coconut is useful
in the treatment of digestive tract infections6. It is also used to
expel intestinal parasites like tapeworms and Helicobacter pylori, which
are responsible for indigestion and ulcer7.
The
oil can be processed and extracted as an organic product which can be employed
in the cosmetic industry for skin care to moisturize the skin, relieve
dryness, flaking and prevent stretch marks. It is used for wounds, bruises,
burns, rashes, eczema, and dermatitis. It also supports the natural chemical
balance of the skin and provides protection from the damaging effects of
ultraviolet radiation from the sun7. Coconut, due to its contents of
caprylic acid, which is fungicidal, is used in the
treatment of fungal skin infections such as athlete’s foot, thrush, ringworm
and candidiasis8. In modern medicine, coconut is used as an immune
system boaster in infants6. It improves digestion and absorption of
other nutrients such as vitamins, minerals and amino acids; prevents obesity
and overweight problems by increasing metabolic rate, regulates thyroid
function, boosts energy and fights fatigue9. Coconut is used in the
treatment of mal-absorption of fat such as cystic fibrosis and enteritis. It
improves insulin secretion and enhances the utilization of blood glucose. This
forms the basis for its use in the management of diabetes10. Coconut
is effective in the treatment and prevention of heart disease, chronic fatigue
syndrome, osteoporosis, gall bladder disease, Crohn’s
disease, prostate enlargement and cancer because of its composition of high and
medium chain fatty acid[7]. It
also reduces inflammation and allergic reactions due to its anti-histamic effect11.
The coconut palm has a multitude of industrial
uses. It provides raw materials for industries such as the wood, furniture and
food industry. Its products includes: timber, food, fermented and unfermented
drink, alcohol, vinegar, thatching material, splint fibres
for making baskets, masts rope, hats, brushes and broom. The palm leaves are
used as a source of fuel and shelter12. It produces utensils for household use such as cups, bowls; oils for
food, illumination, soap and margarine production and ointment12.
The residue after extraction is used in feeding domestic animals and as
fertilizer. Nearly one third of the world’s population depends on coconut to
some degree for their food and their economy.
Several
food uses also exist for coconut products. Coconut is highly
nutritious; rich in fibre, vitamins, and minerals. It
is classified as a “functional food” because it provides many health benefits
beyond its nutritional content2. This work was aimed at investigating the cytoprotective effect of the ethanol extract of coconut on
the gastric mucosal damage induced by indomethacin on
Wistar albino rats and the membrane stabilization
ability of the extract on hypotonicity induced haemolysis of red blood cells.
MATERIALS
AND METHODS:
Animals:
Twenty five adult rats of either sex of
weight 120-200g obtained from the animal house of the Faculty of Biological
Sciences,
Plant
materials:
Matured coconut seeds purchased from the Nsukka local market was cracked and the fresh nuts chopped
into tiny bits and sun-dried. The dried coconut was ground with a mechanical
grinder and macerated in absolute ethanol for 24hrs and filtered with a white
cloth. The filtrate was concentrated using a rotary evaporator at an optimum
temperature of 40o-50oC.
Preparation
of blood sample:
Fresh blood samples (5ml) were collected from
apparently healthy donors (without drug treatment for at least 2 weeks) into
plastic tubes containing 1ml of 3.8% sodium citrate. These test tubes were
centrifuged at 300rpm for 10mins. The red cell pellets were collected and
re-suspended in normal saline equal to 2 times the volume of the supernatant.
Reagents/Chemicals:
All chemicals in this study were of
analytical grade and products of May and Baker,
Phytochemical analysis:
Preliminary Phytochemical tests were carried out on the ethanol extract
of coconut using the methods of Harborne13 and Trease
and Evans14.
Indomethacin induced ulcer:
This assay was carried
out using the method of Urushidani et al.15. Twenty five adult rats randomly divided into 5
groups of 5 rats each were deprived of food for 18hrs and treated per orally
with normal saline and varying doses of the plant extract. The extracts and
drugs used were freshly prepared as a suspension in normal saline and
administered per orally to the animals in 5ml/kg doses. Group 1 (normal
control) was administered normal saline (5ml/kg). Groups II, III and IV were
treated with 100mg/kg, 200mg/kg and 400mg/kg of the coconut extract
respectively. Group V (reference group) was administered 100mg/kg of ranitidine
(standard anti ulcer drug).
Table 1:
Effect of coconut extract on indomethacin induced
gastric ulcer in rats
|
Treatment |
Dose
(mg/kg) |
Ulcer
index |
%
Ulcer inhibition |
|
Control (normal saline) |
5ml/kg |
3.18 ± 1.81 |
|
|
Extract |
100 |
1.1 ± 0.54* |
65.4 |
|
Extract |
200 |
1.02 ± 0.68* |
67.9 |
|
Extract |
400 |
0.95 ± 0.81* |
70.1 |
|
Ranitidine |
100 |
0.27 ± 0.09* |
91.5 |
Values shown are mean ± SD. (N= 5).
*Significantly different from control at p<0.05. N= 5
Table 2:
Effect
of coconut extract on hypotonicity induced haemolysis of red blood cells. (Membrane stabilization
effect of the extract)
|
Treatment |
Extract
volume (ml) |
Normal
saline (ml) |
Distilled
water (ml) |
RBC
(blood) (ml) |
Absorbance |
%
inhibition of haemolysis |
|
Isotonic solution |
- |
2.4 |
- |
0.1 |
0.05 |
-- |
|
Hypotonic solution |
- |
1.9 |
0.5 |
0.1 |
0.75 |
-- |
|
Test sample |
0.1 |
1.8 |
0.5 |
0.1 |
0.67 |
11 |
|
Test sample |
0.2 |
1.7 |
0.5 |
0.1 |
0.27 |
69 |
|
Test sample |
0.4 |
1.5 |
0.5 |
0.1 |
0.09 |
87 |
|
Test sample |
0.6 |
1.3 |
0.5 |
0.1 |
0.08 |
89 |
|
Test sample |
0.8 |
1.1 |
0.5 |
0.1 |
0.075 |
89 |
|
Test sample |
0.9 |
1.0 |
0.5 |
0.1 |
0.055 |
92 |
|
0.2ml indomethacin |
- |
1.7 |
0.5 |
0.1 |
0.065 |
91 |
Thirty minutes later,
50mg/kg of indomethacin was administered (p.o) to the rats. After 8hrs, each animal in the groups was
sacrificed by chloroform anaesthesia and the stomach removed and opened along
the greater curvature, pinned flat on a board, examined and scored for ulcer.
Erosions formed on the glandular portions of the stomach were counted and the
ulcer index calculated as described by
Determination
of membrane stabilization effect of coconut extract on hypotonicity
induced haemolysis of red blood cells:
This assay was carried
out by a modified method of Shinde et al.17. The effect of the ethanol extract of coconut on
haemolysis induced by distilled water was evaluated by incubating various
concentrations of the extract with 0.1ml of the sodium citrate treated blood,
normal saline and distilled water in a test tube for 1hr at 37oC in
a water bath. After the incubation, the test tubes were centrifuged at 300rpm
for 10mins to terminate the reaction. The absorbance of the supernatants
collected was read at 418nm. These experiments were done in triplicates and
mean absorbance values taken. The effect of the standard anti-inflammatory
drug, indomethacin was determined as a positive
control. Changes in absorbance were used to assess the extent of haemolysis;
hence membrane stabilization. Percentage inhibition of haemolysis by the
extract was calculated thus:
% Inhibition of
Haemolysis =
Where OD1 =
Absorbance of isotonic solution
OD2 =
Absorbance of test sample
OD3 =
Absorbance of hypotonic solution.
Statistical analysis:
The
results were expressed as mean ± SD and test of statistical significance were
carried out using one-way ANOVA, correlation and T–test. The statistical
package used was statistical package for social sciences (SPSS) version 15.0
RESULTS:
Phytochemical analysis of the
ethanol extract of coconut shows the presence of phtochemicals
such as alkaloids, resins, steroids, flavonoids, terpenoids and glycosides, and macronutrients like fats and
oil, reducing sugar, carbohydrate and proteins.
Data from Table 1 show that indomethacin induced gastric ulcer in all the experimental
groups. Groups administered with 100mg/kg, 200mg/kg and 400mg/kg of coconut had
significant reductions (P<0.05) in the ulcer indices as compared to control,
and with high percentage level of ulcer inhibition which was comparable with that
of the standard drug, ranitidine.
Data from Table 2 show that the coconut
extract exhibited high membrane stabilization effect against hypotonicity induced haemolysis
of the red cells. This inhibition of haemolysis was
found to be dose dependent, increasing with increased concentration of the
extract in the medium and was comparable with that of indomethacin,
a standard anti-inflammatory drug.
DISCUSSION:
In the present study,
significant protection against indomethacin induced
gastric mucosal ulceration was observed when the animals were administered with
100mg/kg, 200mg/kg and 400mg/kg of the coconut extract. 100mg/kg caused a 65.4%
reduction in ulcer index; 200mg/kg caused a 67.9% reduction while 400mg/kg
caused a 70.1% reduction comparable to the 91% reduction recorded for
ranitidine, the standard anti-ulcer drug. This report is consistent with that
of Fife7 which reported the use of coconut oil in the treatment of
stomach ulcers. Stomach ulcer results from an injury or
damage to the gastric mucosal lining of the stomach which could be as a result
of excess or an overproduction of hydrochloric acid, an acid normally present
in the digestive juices of the stomach or due to complications resulting from
an infection with Helicobacter pylori18.
It also results due to excess intake of non- steroidal anti-inflammatory drug
(NSAIDs) such indomethacin, aspirin and
ibuprofen. Gastric ulcers
induced by these drugs is related with the inhibition of cyclooxgenase 2 enzyme which synthesizes prostaglandin
needed to maintain the integrity of the gastric lining of the stomach19.
In this study, the ethanol extract of coconut exhibited anti-ulcerogenic effect against indomethacin
induced gastric ulcer, which is comparable with that obtained for ranitidine,
an antiacid used to neutralize intraluminal
acid, improve gastric microcirculation and reduce the absorption and
concomitant adverse drug interactions of many NSAIDs21. This result
supports that of Nneli and Woyike22 which
showed that coconut milk and water exhibited anti-ulcerogenic
effect against indomethacin induced ulcer and
suggests that coconut may act by reducing the intestinal absorption of indomethacin and its resulting drug interactions.
The effect of the
coconut extract on haemolysis induced by distilled water evaluated by
incubating various concentrations of the extract with red blood cells and
distilled water showed a reduction in the haemolysis of the red cells with the
incubation of coconut in a dose dependent manner (Table 2). During
inflammation, there are lyses of lysosomes which
release their component enzymes which produce a variety of disorders22.
Since human red blood cell (RBC) membranes are similar to lysososmal
membrane, human RBC stabilization was therefore used as a method to study the
mechanism of action of anti-inflammatory agents23.
Hypotonicity induced haemolysis of red blood cells occurs due to water uptake by
the cells and leads to the release of haemoglobin
which absorbs maximally at 418nm. Hence, the reduced optical density at 418nm
obtained for the various coconut test samples is a reflection of the
stabilization of the red cell membrane caused by the extract. Iwu[11] reported that
coconut reduces inflammation and allergic reactions due to its anti-histamic effect. The stabilizing effect of coconut extract on lysosomal membranes as seen in this study suggests a
possible mechanism of action for the anti-inflammatory effect of coconut by
reduction in edema which occurs during inflammation.
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Received on 03.01.2010
Accepted on 05.02.2010
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