British Journal of Pharmacology and Toxicology 3(2): 89-92, 2012
ISSN: 2044-2467
© Maxwell Scientific Organization, 2012
Submitted: February 29, 2012
Accepted: March 16, 2012
Published: April 25, 2012
Protective Effect of Allium sativum against Liver Injury Induced by AntiTubercular Drugs in Rats
1
B. Bello and 2A.M. Wudil
Trypanosomiasis Research Department, Nigerian Institute for Trypanosomiasis Research
(NITR), P.M.B. 2077, Kaduna, Nigeria
2
Department of Biochemistry, Bayero University Kano, P.M.B. 3011, Kano, Nigeria
1
Abstract: Allium sativum has been reported to have a lot of therapeutic potentials such as antihypertensive,
antimicrobial and hypocholesterolemic. This study has investigated its effect on anti-tubercular drugs
hepatotoxicity. Wistar albino rats were pretreated and co-administered orally with aqueous solution of Allium
sativum. Eighteen rats were divided into six groups of three rats each. Group 1 were normal, while Group 2
were test control administered with anti-tubercular drugs; isoniazid (27 mg/kg bw) and rifampicin (54 mg/kg
bw). Groups 3 and 4 were pretreated with 100 and 200 mg/kg of Allium sativum for 28 days, then administered
with isoniazid and rifampicin at doses 27 and 54 mg/kg respectively for same duration. In groups 5 and 6, same
doses of Allium sativum and anti-tubercular drugs were administered concurrently for twenty eight days. Serum
levels of Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Alkaline Phosphatase (ALP)
and unconjugated bilirubin (uBIL) were estimated 24 h after administration of the last dose. The results showed
that pretreatment and co-administration of Allium sativum solution significantly reduced (p<0.05) serum ALT,
AST and ALP activities and uBIL concentration in the rats, compared to the test control administered with antitubercular drugs only, to induce liver damage. The results suggest that aqueous extracts of Allium sativum can
be said to have protective effect on anti-tubercular drugs hepatotoxicity in rats.
Key words: Allium sativum, anti-tubercular drugs, hepatotoxicity, isoniazid, liver enzymes, rifampicin
about 9% of patients treated for active TB (Yee et al.,
2003; Tasduq et al., 2005). However, currently available
second-line drugs used to treat MDR-TB are four to ten
times more likely to fail than the standard therapy for drug
susceptible tuberculosis (Nikalje and Mudassar, 2011).
Tuberculosis is a systemic disease caused by
Mycobacterium tuberculosis (Ouatarra et al., 2011),
which most commonly affects the lungs but can also
involve almost any organ of the body (George and
Stoppler, 2010). With nearly one-third of the global
population infected by Mycobacterium tuberculosis, TB
remains a major cause of death (1.7 million in 2006),
(Aristoff et al., 2010). An anti-TB regimen is considered
useful when more than 90% of patients are cured and
fewer than 5% of patients develop serious intolerance
(WHO, 2003).
Allium sativum (garlic) has been shown to have a lot
of therapeutic potentials such as; antihypertensive
(Krishnaraju et al., 2006), anti-rheumatic, stimulant, in
treatment of asthma, cold, diabetes, paralysis and chronic
fever (Morakinyo et al., 2008; Nadkarni, 1994). It was
also found to possess hypocholesterolemic effect (Siligaly
and Neil, 1994) and strong antimicrobial activity (Sood
INTRODUCTION
All drugs have the potential to cause injury and in
many cases, such adverse effects can outweigh the
benefits (Fingerote, 2008). Drug-induced liver injury is an
important and commonly encountered adverse effect with
anti-tuberculosis therapy (Sharma, 2004), which
comprises of 2 months of Isoniazid (INH), Rifampicin
(RMP) and Pyrazinamide (PZA) with or without
Ethambutol (ETH), followed by 4 months of treatment
with INH and RMP (WHO, 2003; Blumberg et al., 2003).
The two main drugs INH and RMP are in the arsenal due
to their high bactericidal power (Migliori et al., 2007).
During the first 2 months intensive phase of TB treatment,
INH kills 90% of viable bacilli, this renders the patient
non infectious and reduces the risk of drug resistance
(Donald and Schaaf, 2007). During the 4 month
continuation phase, RMP kills the last remaining bacilli
while INH assists in preventing drug resistance. AntiTubercular Drugs-induced Hepatotoxicity (ATDH) is a
potential adverse effect of the currently used anti-TB
regimens involving isoniazid, rifampicin and
pyrazinamide with or without ethambutol and occurs in
Corresponding Author: B. Bello, Trypanosomiasis Research Department, Nigerian Institute for Trypanosomiasis Research (NITR),
P.M.B. 2077, Kaduna, Nigeria
89
Br. J. Pharmacol. Toxicol., 3(2): 89-92, 2012
rats each. The drugs and garlic solution were administered
orally. Group 1 comprised of the normal rats, while group
2 served as the test control administered with INH (27
mg/kg bw) and RMP (54 mg/kg bw) only for 28 days to
induce liver damage. Groups 3 and 4 were pretreated with
100 and 200 mg/kg bw of garlic solution respectively for
28 days then administered with INH (27 mg/kg bw) and
RMP (54 mg/kg bw) from 29 to 56th day. Groups 5 and 6
were administered with same doses of the garlic solution
and drugs concurrently for 28 days.
The rats were sacrificed 24 h after the last
administration. Blood samples were collected and Serum
Liver Transaminases (ALT and AST), Alkaline
Phosphatase (ALP) activities and Unconjugated Bilirubin
(uBIL) concentration were estimated.
et al., 2003). Wattenberg (1990) has shown its high
potential in the prevention of cancer. Sang et al. (1995)
have demonstrated that garlic oil is effective against fat
infiltration of the liver. In combination with propranolol,
garlic homogenate offered protection from myocardial
injury (Asdaq et al., 2008). Garlic has also been reported
to exert protective effect on isoprenaline induced
myocardial infarction (Vibha et al., 2011) and
nephrotoxicity caused by amikacin (Iman and Mahmoud,
2011).
In recent years, many researchers have examined the
effects of plants used traditionally by indigenous healers
to support the treatment of liver diseases. Triphala
(Mahaboob et al., 2007), Senna occidentalis (Nwaehujor
et al., 2011) and Parkinsonia aculeata (Hassan et al.,
2008) have all yielded positive results.
This study investigated the protective effect of Allium
sativum in hepatotoxicity caused by anti-tubercular drugs
in rats.
Assessment of liver damage:
Biochemical investigations: Serum AST and ALT
activities were determined using the method of Reitman
and Frankel (1957), uBIL was estimated by the method of
Jendrassik and Grof (1938) and ALP estimated using the
method of Roy (1970).
MATERIALS AND METHODS
Animals: Eighteen wistar albino rats weighing 120-140
g were obtained from the Animal House, Department of
Biological Sciences, Bayero University, Kano. The
animals were housed in cages in a room where a 12 h
light/dark cycle was maintained. They were allowed free
access to water and feed (a product of Grand Cereals and
Oil Mills Ltd, Jos, Nigeria) throughout the experimental
period.
Statistical analysis: All results were expressed as
mean±SD for each group. Data were analysed with
student’s t-test using SPSS. P values of less than 0.05
(p#0.05) were considered significant.
RESULTS AND DISCUSSION
The results in Table 1 showed increase in the
analysed biochemical parameters in the test control
(Group 2), compared to the normal control (Group 1).
This increase is in line with the proven hepatotoxic effects
of INH and RMP. Administration of garlic both in
pretreatment and co-administration significantly (p#0.05)
reduced serum ALP, AST and ALT activities and uBIL
concentration in groups 3-6. Reduction in serum ALP
activity was more profound in group 4, while group 5
exhibited the most reduced AST activity compared to the
test control. Pretreatment with 100 mg/kg bw of garlic
solution (Group 3) lowered serum ALT activity better
than groups 4-6. The same treatment favoured serum
uBIL by decreasing the concentration, compared to the
test control group.
Drugs: Isoniazid tablets BP (300 mg) Microlabs Ltd.,
India. Rifampicin capsules BP (300 mg) Maxheal
Pharmaceuticals, India. Garlic once-a-day tablets (300
mg) Kwai® Klosterfrau, Germany.
Preparation of garlic solution: One garlic tablet was
dissolved in 100 mL of distilled water to make a 3 mg/mL
solution administered to the rats.
Experimental design: The study was conducted at the
Animal House, Department of Biological Sciences,
Bayero University Kano between September to
December, 2010. Rats were divided into 6 groups of three
Table 1: Effect of pretreatment and co-administration of Allium sativum and anti-tubercular drugs on serum ALP, AST, ALT activities and uBIL
concentration in rats
Groups
Dose of extracts (mg/kg)
ALP (IU/L)
AST (IU/L)
ALT (IU/L)
uBIL (:moL/L)
Group 1 (normal)
29.33±3.60
17.00±9.90
6.00±1.40
2.49±0.49
Group 2 (test control)
51.00±4.20
52.66±4.60
25.33±12.60
7.46±1.80
37.00±11.70a,b
8.33±1.20a,b
1.50±0.40b
Group 3
Pretreatment 100
47.33±6.20a,b
Group 4
Pretreatment 200
39.66±3.40a,b
17.00±1.40b
12.33±2.10a
4.33±1.60a,b
Group 5
Co-administration 100
40.66±0.40a,b
14.66±0.80b
12.33±4.20a,b
2.56±0.40a,b
Group 6
Co-administration 200
42.66±2.60b
33.33±3.80b
21.66±10.60a,b
2.89±0.20a,b
n: 3; a: Significant increase (p#0.05) as compared with the test control group; b: Significant decrease (p#0.05) as compared with the normal control
group
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Br. J. Pharmacol. Toxicol., 3(2): 89-92, 2012
Damage to the structural integrity of the liver is
reflected by an increase in the level of serum
transaminases (Schmidt et al., 1975) because these are
cytoplasmic in location and are released into the
circulation after cellular damage (Sallie et al., 1991).
Anti-tubercular drugs hepatotoxicity is characterised by
elevations of serum uBIL concentrations and AST, ALP
and ALT activities which has been observed in the course
of this study. Oral administration of garlic solution both
in the pretreated and co-administered groups significantly
decreased levels of the above parameters and thus
conferring a protective effect on the liver.
The constituents of garlic are reported to inhibit
Phase I drug metabolism through specific inhibition of
cytochrome P-450 enzymes, while they enhance the
activities of Phase II enzymes that are involved in the
conjugation and excretion of drugs and their Phase I
metabolites (Guyonnet et al., 2002). This may play an
important role in the detoxification of toxic metabolites
postulated to be involved in ATDH. Furthermore, many
steroidal saponins and sapogenins are present in garlic
(Matsuura, 2001) and could play vital roles as antiinflammatory agents, in the induction of protein synthesis
and in tissue regeneration and repair. The interplay of a
wide range of phytochemicals (allicin, ajoene, diithin,),
vitamins (A, B1, C), antioxidants (glutathione)
phytochemicals (quercetin, cyanidin), amino acids (Met,
His, Cys, Phe, Ile) and minerals (Ca, Se, Mn, Cu, P, Mg,
Zn, K, Na, Fe) (Agarwal, 1996) whose synergy can
contribute immensely to the restoration of enzyme
activities and prevention of cellular degeneration may also
account for the hepatoprotective effect of garlic.
Based on the findings from this study which are in
agreement with Ezeala et al. (2009) who reported on
protective effect of garlic on acetaminophen-induced liver
injury, Shaarawy et al. (2009), who reported the
protective effects of garlic and silymarin on NDEAinduced rats hepatotoxicity and Obioha et al. (2009), who
studied the hepatoprotective potentials of onion and garlic
extracts on cadmium-induced oxidative damage in rats, it
can be concluded that Allium sativum (garlic) can serve as
a potential protective agent against liver injury caused by
anti-tubercular drugs.
ACKNOWLEDGMENT
The authors wish to thank Dr. J.N. Ja’afar, PhD
student at Universiti Sains Malaysia for his efforts in the
literature search. Also, Mallam Yakubu Otaru of the
Animal House, Department of Biological Sciences,
Bayero University, Kano.
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