The areas of the world. This was the

The toxicity of
petroleum hydrocarbon across the living systems is now a common knowledge among
the scientific community. What is lacking is a mini-scale antidote that can be
adopted by the inhabitants of crude oil producing areas of the world. This was
the reason for this study. The study was comprised forty eight female Wister
rats divided into six groups of eight rats each. The rats were fed as described
thus. Group 1: ((normal Control). Group 2:  
feed mixed with 5.0g oil palm leaf. Group 3: feed mixed with 10.0g oil
palm leaf. Group 4: Feed mixed with 4ml crude oil (Crude oil Control). Groups 5
and 6: Contaminated diet mixed with ground oil palm leaf (5.0 g and 10.0 g
respectively). At the end of exposure periods (three and six months
respectively), the rats were sacrificed and the kidney used to prepare
supernatant used for the determinations oxidative stress indices (lipid
peroxidation and xanthine oxidase activity). The results show that pretreatment
of crude oil contaminated diet with oil palm leaf tend to restore values of
lipid peroxidation and xanthine oxidase activity close to control values. Thus,
it is pertinent to state that there exist potentials in the use oil palm leaf
in the treatment of crude oil toxicity. And indeed setting a fresh agenda for
further serious scientific investigations

 

 

 

Keywords: Crude oil,
Kidney, Lipid peroxidation, Oil palm, .Xanthine oxidase,

 

 

 1.0 Introduction

 Humans
and animals get exposed to crude oil or its byproducts when these chemicals are
released into surrounding environment during oil exploration activities,
equipment failures, corrosion, illegal bunkering, usage, oil theft and illicit refining
1-3. Crude oil stimulates oxidative stress in animals 4, 5. Lipid
peroxidation and xanthine oxidase activity are part of oxidative stress
indices. Lipid peroxidation elicits oxidative damage in plants and animals and
its value in conjunction with alterations in the level of antioxidants
represent a measure of oxidative stress. Similarly, the activity of xanthine
oxidase is an example of defense mechanism as well as a measure of oxidative
stress 6. Report indicated that crude Petroleum oil is harmful to the kidney
and the deleterious action is based on oxidative stress 7.

Many byproducts of the oil palm tree are  medicinal, the juice  from palm leaves have wound healing property
while the sap is used as laxative 8.This is due to the presence of  biologically active compounds rich in medicinal
and antioxidant properties 9, 10.  Earlier
report confirmed the presence of phytochemicals namely flavonoid, tannin and
phenols in the leaves of oil palm, hence its ability as an effective antioxidant
11. In fact, oil palm leaf extract contains more antioxidative phenolic
compounds than various green tea extracts 12. Oil palm leaf extract is a
potential new source of functional food ingredient, based on reports of its health
benefit 13 .This study is aimed at evaluating the protective potentials of
oil palm leaf against crude oil contaminated diet induced nephrotoxicity in
rats.

2.0 Materials and methods

The crude oil used
for this study was obtained from Nigeria National Petroleum Corporation (NNPC)
Warri, Delta State, Nigeria. The palm frond used was obtained from Elaeis
guineensis tree in Obiaruku, Delta state, Nigeria Forty eight (48) female
albino wistar rats with weights ranging from 0.088kg to 0.182 kg obtained from
the animal house of Department of Anatomy, Delta State University, Abraka were
used for this study. The rats were housed in a standard wooden cage made up of
wire gauze, net and solid woods and left to acclimatize for one week on
grower’s marsh and tap water at laboratory temperature
of 28C and 12 hour day/ night regime. After the acclimatization period,
the rats were weighed and grouped.

2.1 Preparation of leaf powder.

The
leaves were isolated from the stock and sun- dried. The dried leaf was then
ground with domestic kitchen blender into a fine powder and stored in a clean
and sealed plastic container

2.2Treatment of animals

The forty eight (48) female albino wistar
rats were assigned to six (6) groups according to their weights, with eight
rats in each group. Rats in the control group which is Group 1 were fed with
grower’s marsh only. Rats in Group 2 were fed with grower’s marsh and 5g of
powdered palm frond. Group 3 rats were fed with grower’s marsh and 10g of
powdered palm leaves. Group 4 rats were fed with grower’s marsh contaminated
with crude oil (4ml per 100g of feed). Rats in Group 5 were fed grower’s marsh
contaminated with crude oil (4ml per 100g of feed) plus 5g of powdered palm
fronds. While rats in Group 6 were fed with crude oil contaminated marsh (4ml
per 100g of feed) plus 10g of powdered palm leaves. The rats in each group were
allowed access to clean drinking water while the experiment lasted. The feeds
were prepared fresh daily and stale feed remnants were discarded regularly. The
animals in each group were exposed to their respective diets for three and six
months respectively. The National Institute of
health guide for the care and use of laboratory animals (NIH, 1985)
was
adopted all through the experiment

 

 

 

 

2.3 Collection of
samples

After the first
exposure period( three months),  four rats
from each group were sacrificed and the kidneys were harvested. Five grams (5.0
g) of the kidneys were weighed in chilled conditions and homogenized with 5ml
of normal saline in a mortar. The mixture was diluted
with known amount of buffered saline before being centrifuged and the
supernatant was transferred into plastic tubes and stored at – 4C before used
for analysis within forty eight hours. This same procedure was adopted after
six months exposure period.

2.4 Determination of
lipid peroxidation and xanthine oxidase activity

The activity of xanthine oxidase in the kidney of
rats was measured using the method of Bergmeyer et. al. 14, based on the
oxidation of xanthine to uric acid, a molecule that absorbs light maximally at
290 nm. A unit of activity is that forming one micromole of uric acid per
minute at 25oC. Lipid peroxidation in the kidney of rats was
measured by the thiobarbituric acid reacting substances TBARS, method of Gutteridge
and Wilkins 15.

2.5Statistical Analysis

Analysis of variance (ANOVA) and post Hoc Fisher’s
test for multiple comparison was performed using statistical package for social
science (SPSS), version 20  to determine statistical significant differences between means. P values
<0.05 were taken as being significantly different   3.0 Results and Discussion The effects of Elaeis guineensis leaf on kidney lipid peroxidation and xanthine oxidase activity against crude oil induced nephrotoxicity in rats after three and six months are shown in tables 1 and 2.  Lipid peroxidation in the kidney rats exposed to crude oil contaminated ( group 4) was significantly (P<0.05) higher in comparison with the control (group 1). Rats fed palm leave pretreated diets (Group 2 and 3) showed significantly lower kidney levels of lipid peroxidation when compared with the control (group 4). Moreover, rats fed crude oil contaminated diets that was pretreated with various amounts of oil palm leaves (Group 5 and 6) exhibited significantly lower kidney lipid peroxidation level when compared with the control (group 1) and  rats fed crude oil contaminated diet alone (group 4) .  Lipid peroxidation, which is a potential marker of oxidative stress, induce disturbance of cell membrane, and functional loss of biomembranes, that results in inactivation of membrane bound receptors and enzymes 16, 17, 18. The present study shows that the consumption of crude oil contaminated diet increased the level of lipid peroxidation in rats.  This study shows that exposure to hydrocarbons present in crude oil can lead to oxidative damage of the kidney as evident by the rise in renal level of lipid peroxidation. This is based on the premise that  metabolism of hydrocarbons present in crude oil generate free radicals 19. This is in consonance with previous studies by 5, 6, 7, 20. Oil palm (Elaeis guineensis) frond is rich in bioactive phytochemicals such as polyphenols and these polyphenolic compounds are considered to have antioxidant activity that is several folds higher than that of vitamins C and E 21, 22, 23.This may be the basis for the decreased level of lipid peroxidation in the kidney of rats exposed to crude oil that was treated with oil palm leaf The kidney xanthine oxidase activities were significantly (P<0.05) lower  in  rats fed crude oil contaminated diets (group 4) in comparison with all the experimental groups( Tables 1 and 2).Rats fed with oil palm leaf treated crude oil contaminated diet  (Groups 5 and 6) have significantly higher xanthine oxidase activities in the kidney when compared with rats fed with crude oil contaminated diet only (group 4). However, rats fed with only oil palm leaf treated diets (Groups 2 and 3) have significantly higher kidney xanthine oxidase activity when compared with rats fed with only crude oil contaminated diet (group 1). Xanthine oxidase is involved in phase one process in the inactivation of xenobiotics in animals 24. The increase in the activity of xanthine oxidase in rats exposed to oil palm leaf treated diet indicates response of the enzyme to enhance the metabolism of endogenous xanthine. This is in a bid to increase the production of uric acid, a potent antioxidant 7, 24, 25. The decrease in activity of xanthine oxidase in rats exposed to crude oil contaminated diet alone shows that the metabolism of crude oil hydrocarbons leads to a reduced ability to produce uric acid Nevertheless, the increase in the activity of oxidative enzymes had been reported as a measure of oxidative stress 26. However, addition of ground oil palm leaves resulted in decrease in toxic effects of crude oil. This is exhibited in the decrease in xanthine oxidase activity in rats fed with crude oil contaminated diets that were pretreated with oil palm leaves. This is due to the ability of oil palm leaves to act as an antioxidant, protecting endothelial cells of the kidney against reactive free radicals thereby decreasing the level of antioxidant enzymes 11, 13. Substances with antioxidant potentials possess health promoting properties, since they quench free radicals which are involved in many diseases processes 13, 27, 28, 29 This study has indicated that the consumption of crude oil contaminated diet can result in increase in oxidative stress which causes corresponding increases in lipid peroxidation levels and xanthine oxidase activity. However, the crude oil toxicities were reversed by the consumption of diets that were pretreated with oil palm leaves. This study, therefore, shows the protective role of oil palm leaf against crude oil induced nephrotoxicity.