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Research Article
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Hepatotherapeutic Effect of Aloe Vera in Alcohol-induced Hepatic Damage |
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W.A. Saka,
R.E. Akhigbe,
O.S. Ishola,
E.A. Ashamu,
O.T. Olayemi
and
G.E. Adeleke
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ABSTRACT
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There is a lack of reliable hepatotherapeutic drugs in modern medicine in the management of alcohol/drug-induced liver damage. Aloe vera extract has been used in folklore medicine for its medicinal values. This study evaluates the hepatotherapeutic activity of aqueous extract of Aloe vera gel in rats. Sprague-Dawley rats were divided into three groups; the negative control, positive control and the extract-treated groups. The negative control received only distilled water daily. The positive control received alcohol, while the extract-treated group received aqueous extract of Aloe vera and alcohol. Hepatotoxicity was induced in the positive control and extract-treated rats with alcohol. The hepatotherapeutic effect was evaluated by performing an assay of the serum total bilirubin, alkaline phosphatase, aspartate and alanine transaminases and liver histopathology. Alanine transaminase activities were comparable in all groups. Alcohol treatment alone significantly (p<0.05) increased total serum bilirubin, alkaline phosphatase and aspartate transaminase activities. Alcohol-induced hepatic dysfunction was abrogated by Aloe vera extract. Histopathological examination revealed that alcohol induced hepatic damage. Aloe vera treatment maintained hepatic architecture similar to that seen in the control. This study shows that aqueous extract of Aloe vera gel is hepatotherapeutic and thus lends credence to the use of the plant in folklore medicine in the management of alcohol-induced hepatic dysfunction.
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Received: August 08, 2011;
Accepted: October 12, 2011;
Published: November 19, 2011
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INTRODUCTION
Folklore medicine has grown from time antiquity since the use of natural plants
is cheap and believed to be free of side effect. The medicinal values of Aloe
vera have made it widely used plant (Capasso et al.,
1998; Vogler and Ernst, 1999). There are numerous
species of aloes (Hu et al., 2003). It is an
arborescent, pea green colour-plant of the Asphodelaceae (Liliaceae) family.
At the center of the leaf is a parenchymal gel, which could be dried or diluted
in water to form concentrated or diluted aloe juice products respectively. It
contains laxative anthraquinones (Schulz et al., 1979;
Sharrif Moghaddasi and Verma, 2011).
Previous studies have documented its antidiabetics (Bolkent
et al., 2005; Rajasekaran et al., 2006;
Karim, 2011), anti-inflammatory and anti-oxidant (Singh
et al., 2000; Hu et al., 2003; Yagi
and Takeo, 2003; Miladi and Damak, 2008) and anti-tumour
(El-Shemy et al., 2010) activities. Though most
of its ethnomedicinal potentials have been ascribed to its polysaccharide contents
(Ni and Tizard, 2004; Ni et al.,
2004). Dagne et al. (2000) suggested that
its biological properties should be attributed to a synergistic action of all
its phytochemical constituents.
The liver is responsible for the metabolic homeostasis of the body including
biotransformation, detoxification and excretion of many endogenous and exogenous
compounds (www.sharinginhealth.ca/biology/liver.html).
No scientific data is available concerning the hepatoprotective potentials of
Aloe in alcohol-induced hepatic damage. Hence, this study focused on evaluating
the hepatotherapeutic effect of Aloe in alcohol-induced liver damage.
MATERIALS AND METHODS
Animals: Sprague Dawley rats, of both sexes, weighing between 150 and
180 g were used for the experiment. They were housed in standard rat plastic
cages under laboratory conditions with 12:12 h light/dark cycle at 25°C±2.
The animals were allowed to acclimatize for two weeks (Eghoghosoa
et al., 2011).
Treatment: Animals were randomized into three groups; the negative control, positive control and the extract-treated groups. The negative control received only 2 mL of distilled water daily. The positive control received 2 mL of 10% alcohol, while the extract-treated group received 1 mL of the aqueous extract of Aloe vera and 2 mL of 10% alcohol. Treatments lasted for 4 weeks.
Extraction of aqueous extract of Aloe vera: Aqueous extract of Aloe
vera was obtained as previously described (Saka et al.,
2011). Briefly, fresh stems of Aloe vera were washed thoroughly to get rid
of all forms of debris. The leaves were then sliced longitudinally to cut open
the inner part of the leaves. The gel in the leaves was scrapped into a clean
bowl and blended to obtain a finer and liquefied form of the gel, the aloe juice.
The juice was refrigerated below 4°C for preservation (Ige
et al., 2011).
Blood sample collection: After the experimental period, blood sample
was collected from the animals by jugular puncture. Rats were anaesthetized
in chloroform vapour. The neck was quickly cleared of fur and skin to expose
the jugular veins. The veins after being slightly displaced to avoid contamination
with interstitial fluid were sharply cut with a sterile scalpel (Oladiji
et al., 2007) and blood was collected into lithium-heparinized bottles.
Sera were obtained by centrifuging at 3000 rpm for 15 min (Akhigbe
et al., 2008) and liver function test was done.
Assessment of liver function and histopathological examination: Alkaline phosphatase, aspartate aminotransaminase, alanine aminotransaminase and total bilirubin were determined using standard laboratory kit according to manufacturers instruction.
The excised livers were used in normal saline and fixed immediately in 10%
formalin solution. A paraffin embedding technique was carried out and sections
were taken at 5 mM thickness, stained with hematoxylin and eosin and examined
microscopically for histopathological changes (Preece, 1972).
Statistical analysis: Data are presented as Mean±standard error of mean (n = 5). Statistical analyses used one-way Analysis of Variance (ANOVA) to account for the different treatments and were complemented with unpaired t-test. Differences were considered statistically significant at p<0.05. RESULTS
Liver functions are summarized in Fig. 1-4.
Alanine aminotransaminase (ALT) activities were comparable in all groups, though
there was a marginal insignificant raise in alcohol-treated group compared to
other groups.
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Fig. 1: |
Effect of aloe vera aqueous extract on serum alkiline phosphatase
in alcohol-induced hepatic damage; bars carrying different letters are significantly
different (p<0.05) |
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Fig. 2: |
Effect of aloe vera aqueous extract on serum alanine aminotransaminase
in alcohol-induced hepatic damage; bars carrying different letters are significantly
different (p<0.05) |
Alkaline Phosphatase (ALP), Aspartate Aminotransaminase (ASP) and Total Serum
Bilirubin (TSB) were significantly increased in alcohol-treated group. These
rises were significantly abrogated by Aloe vera Extract (AvE).
The histopathological examination of the negative control group livers showed a normal arrangement of the hepatocytes, with clearly visible nuclei, central vein and portal triad. Areas of congestion of sinusoids, cloudy swelling, congestion of central vein, centrilobular fatty change and necrosis of hepatocytes were seen in animals treated with alcohol. There was marked reduction in sinusoidal congestion, cloudy swelling and fatty change, with areas of regeneration in animals treated with AvE (Fig. 5).
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Fig. 3: |
Effect of aloe vera aqueous extract on serum aspartate aminotransaminase
in alcohol-induced hepatic damage; bars carrying different letters are significantly
different (p<0.05) |
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Fig. 4: |
Effect of aloe vera aqueous extract on serum bilirubin in
alcohol-induced hepatic damage; bars carrying different letters are significantly
different (p<0.05) |
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Fig. 5: |
Effect of aloe vera aqueous extract on serum bilirubin in
alcohol-induced hepatic damage bars carrying different letters are significantly
different (p<0.05) |
DISCUSSION
Polysaccharides, carbohydrates, proteins, amino acids, vitamins, lipids, inorganic
compounds, chromones, anthraquinones/anthrones, triterpenoid, flavonoids and
some enzymes and hormones are the constituent phytochemicals in Aloe vera (Hu
et al., 2003; Hamman, 2008; Sharrif
Moghaddasi and Verma, 2011).
Hepatic damage is characterized by a rise in serum enzymes viz ALT, AST and
ALP. Generally, ALT concentrations are consistently higher than AST levels and
this is expected as body cells generate more ALT than AST (Mayne,
1996). Most ALT is found in the mitochondria, unlike AST which is entirely
cytosolic. Thus, AST is a more sensitive marker of hepatocellular damage than
ALT (Al-Mamary et al., 2002).
The administration of alcohol to the animals resulted in significant rise in
serum ALP, AST and TSB. Administration of AvE ameliorated the toxic effect of
alcohol. Compared with the alcohol-treated animals, AvE caused a significant
decrease in ALP, AST and TSB levels. However, ALT levels were similar in all
groups. The observed increase in the concentrations of ALP and AST is indicative
of loss of the functional integrity of the hepatic cell membranes and cellular
leakage of these enzymes into the bloodstream (Lahon and
Das, 2011). Histological study showed normal cytoarchitecture of the control
rats, however, the alcohol-treated animals exhibited areas of hepatic necrosis.
The animals treated with AvE revealed appreciable protection of hepatic tissue
from alcohol. Thus, AvE showed hepatotherapeutic activity. This agrees with
previous studies (Rajasekaran et al., 2006; Saritha
and Anilakumar, 2010) that reported that Aloe vera maintains normal levels
of aminotransaminases, ALP, TSB and hepatic cytoarchitecture integrity.
The hepatoprotective activity of AvE might be associated with its anti-oxidant
and anti-inflammatory potentials against alcohol-induced hepatic damage. AvE
preserved the metabolizing enzymes of the liver through an antioxidant activity
(Chandan et al., 2007), via an inhibitory action
on the arachidonic acid pathway through cyclooxygenase (Vazquez
et al., 1996). It also significantly reduced leukocyte adhesion and
tumour necrosis factor α (Prabjone et al., 2006).
Thus, AvE reduced prostaglandin synthesis and leucocytes infiltration (Cross
and Roberts, 2004) with consequent enhancement of hepatic functions.
The hepatotherapeutic effect of AvE may be attributed to the anti-oxidant properties
of its bioactive principles via a membrane-stabilizing mechanism. This study
thus lends pharmacological support to the folkloric, ethnomedical use of the
plant in the management of alcohol-induced hepatic damage.
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