West Indian Med J 2008; 57 (4): 323
Protective Effect of Carica papaya L Leaf Extract against Alcohol Induced Acute
Gastric Damage and Blood Oxidative Stress in Rats
M Indran, AA Mahmood, UR Kuppusamy
The effects of Carica papaya leaf (CPL) aqueous extract on alcohol induced acute gastric damage and
the immediate blood oxidative stress level were studied in rats. The results showed that gastric ulcer
index was significantly reduced in rats pretreated with CPL extract as compared with alcohol treated
controls. The in vitro studies using 2,2-Diphenyl-1-Picryl-Hydrazyl (DPPH) assay showed strong
antioxidant nature of CPL extract. Biochemical analysis indicated that the acute alcohol induced
damage is reflected in the alterations of blood oxidative indices and CPL extract offered some
protection with reduction in plasma lipid peroxidation level and increased erythrocyte glutathione
peroxidase activity. Carica papaya leaf may potentially serve as a good therapeutic agent for protection
against gastric ulcer and oxidative stress.
Efecto Protectivo del Extracto de la Hoja de Carica papaya L Contra el Daño
Gástrico Agudo Inducido por Alcohol y el Estrés Oxidativo en Ratas
M Indran, AA Mahmood, UR Kuppusamy
Los efectos de; extracto acuoso de la hoja de Carica papaya (CPL) en el daño gástrico agudo inducido
por alcohol y el nivel de estrés oxidativo inmediato en la sangre, fueron estudiados en ratas. Los
resultados mostraron que el índice de úlcera gástrica se reducía significativamente en ratas pre-
tratadas con extracto de CPL, en comparación con los controles tratados con alcohol. Los estudios in
vitro mediante el ensayo con 2,2-difenil-1-picrihidrazilo) mostraron la fuerte naturaleza antioxidante
de extracto de CPL. El análisis bioquímico indicó que el daño agudo inducido por alcohol se refleja
en las alteraciones de los índices oxidativos de la sangre y el extracto de CPL ofreció cierta protección
con la reducción del nivel de peroxidación lipídica del plasma y el aumento de la actividad de la
glutatión peroxidasa de los eritrocitos. La hoja de la Carica papaya puede servir potencialmente como
un buen agente terapéutico para la protección contra la úlcera gástrica y el estrés oxidativo.
West Indian Med J 2008; 57 (4): 1
From: Department of Molecular Medicine, Faculty of Medicine, University
of Malaya, 50603 Kuala Lumpur, Malaysia.
Correspondence: Dr UR Kuppusamy, Department of Molecular Medicine,
Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Fax: +603-7967 6600, E-mail: firstname.lastname@example.org.
The papaya, Carica papaya L, is a member of the small fami-
ly Caricaceae allied to the Passifloraceae. As a dual or multi-
purpose, early bearing, space conserving, herbaceous crop, it
is widely acclaimed, despite its susceptibility to natural
enemies (1). In some islands of the West Indies, it is known
as pawpaw (2). Originally from Southern Mexico, Central
America and Northern South America, the papaya is now
cultivated in most countries with tropical climate like
Malaysia and the West Indies. Carica papaya leave (CPL) is
used as food or as medication in folk medicine. It is con-
sumed as a vegetable by the Malay community in Malaysia
and by the natives in the East Indies. Traditionally, the leaf
extract was used as a tonic for the heart, analgesia and
treatment for stomach ache (3). The extract is also known to
have antioxidant properties (4) but there are no scientific data
reported on the protective effect of this extract on alcohol
induced acute gastric damage. The manifestation of oxida-
tive stress through generation of free radicals is one of the
numerous mechanisms involved in the gastro-toxic effect of
ethanol. Free radicals play an important role in tissue injury
by altering the oxidant-antioxidant equilibrium (5). The al-
tered balance is a risk for the development of various dis-
orders of the digestive tract. An efficient therapy to control
redox status balance in gastric ulcer is important in order to
minimize the damage associated with oxidative stress.
Therefore, in this study, we aimed to investigate whether the
treatment with a single dose of CPL extract (500 mg/kg)
might reduce acute gastric ulceration induced by absolute
ethanol and if it is so, to determine the immediate oxidative
stress level in blood.
The CPLs were collected from Puchong, Selangor, Malaysia
and was identified as C papaya by one of the authors (Kup-
pusamy). A voucher specimen (code: CPL2) was deposited
at the Department of Molecular Medicine, Faculty of Medi-
cine, University of Malaya, Malaysia. The fresh leaves were
cut into small pieces and homogenized in cold distilled water
to obtain the juice which was filtered and subjected to lypho-
lization in a freeze drier. The percentage weight of the freeze
dried plant material was 7.14%. The antioxidant activity of
the crude aqueous extract was measured using the DPPH
assay (6). Male adult Sprague-Dawley rats (body weight
180–220 g) bred and reared in The University of Malaya
animal unit were used for the experiment. All animals
received humane care in compliance with the institution’s
guideline and criteria for humane care as outlined in the Na-
tional Institute of Health Guidelines for the Care and Use of
Laboratory Animals (7). A total of 24 rats were divided into
four groups (6 rats per group). The first group was a control
group treated with 5 ml kg-1distilled water and the second
group was administered with 5 ml of CPL aqueous extract
(500 mg/kg body weight) orally. The third group was admin-
istered a single oral dose of absolute ethanol (1 ml/animal).
The last group was administered with 5 ml (500 mg/kg) CPL
aqueous extract 30 minutes before being given a single oral
dose of absolute alcohol. The rats were sacrificed 20 minutes
later and their stomachs were rapidly removed and fixed in
10% buffered formalin. The gastro-haemorrhagic lesion
index was measured using a microscope with a square grid
eyescope and was expressed as ulcer index (mm2). The
serum was collected in plain and EDTA tubes for various
oxidative marker measurement namely xanthine oxidase
(XO) (EC 126.96.36.199), malondialdehyde (MDA), glutathione
peroxidase (GPx; EC 188.8.131.52 ), catalase (EC 184.108.40.206) and
ferric reducing antioxidant potential (FRAP) based on known
established methods (8). All reagents used for the deter-
mination of oxidative indices were purchased from Sigma
chemicals (St Louis, Mo, USA). Other reagents of analytical
grade were obtained from normal commercial sources. The
data for various parameters were analyzed using Duncan
multiple range test and p < 0.05 was regarded as significant.
The CPL showed a DPPH activity with an IC50of 60.2 µg/
ml. Oral administration of CPLextract before administration
of ethanol led to significant protection of the stomach com-
pared to the control group. There were severe haemorrhagic
lesions visible in the dissected stomach of rats treated with
alcohol alone but in CPL pretreated rats, only mild lesions
were visible (Figs. 1, 2). The gross examination of the
Fig. 1:Necrosis of gasric mucosa (gross). Gastric mucosal damage caused
by absolute ethanol. Absolute ethanol produced extensive visible
haemorrhagic necrosis of gastric mucosa.
Fig. 2:Cytoprotection of aqueous extract 500 mg kg-1against absolute
ethanol. Aqueous extract was able to prevent or reduce the forma-
tion of gastric lesions by absolute ethanol.
stomach showed that the extract alone did not cause any
changes but in the presence of alcohol, thick mucous forma-
tion and increase in pH of the stomach secretion were ob-
served. The crude aqueous extract showed a pH of 9.2. The
Table shows the ulcer index and levels of blood oxidant-
antioxidant markers in the various treatment groups. Rats
treated with CPL had significantly lower MDA levels as
compared to the alcohol treated group. Glutathione peroxi-
Carica papaya L Leaf Extract
dase activity was significantly decreased in blood erythro-
cytes after ethanol treatment, but in rats pretreated with CPL,
a significant increase was observed. In contrast, neither
catalase nor XO showed significant changes in all the treat-
ment groups. In addition, FRAP level was significantly
higher in the alcohol treated group. The ulcer index was
significantly lower (p < 0.05) in the CPL-treated group.
The present result demonstrates that a single dose (500
mg/kg) of CPL aqueous extract is able to protect the rat
gastric mucosa against haemorrhagic lesions produced by
alcohol. This dose was chosen after preliminary assessment
using a wide dose range of this extract (result not shown).
The DPPH method showed strong radical scavenging activity
(antioxidant) and this property is most likely contributed by
polyphenols present in this extract. Oral administration of
ethanol in rat is noxious for the stomach, affecting the gastric
mucosa by disrupting its barrier and provoking pronounced
micro/macrovascular changes a few minutes after its admin-
istration. According to various studies, alcohol induced dam-
age may result from disturbance of pro-oxidant and anti-
oxidant balance that is found in cells (9). In this study, the
measurement of oxidant-antioxidant parameters was done in
blood because it is a better indicator of changes in metabolite
and energy metabolism related enzyme activity. In addition,
erythrocytes are highly sensitive to peroxidative damage
probably due to the high content of unsaturated fatty acid in
their membrane (10). Malondialdehyde, an end product of
lipid peroxidation, is widely used as a marker of lipid per-
oxidation. Glutathione peroxidase is an important enzyme
which plays a key role in the elimination of hydrogen
peroxide and lipid hydroperoxide in gastric mucosa cells.
Currently, there is a consensus that former deleterious effects
of alcohol on gastric mucosa are the consequence of
enhanced lipid peroxidation and decreased GPx level or vice
versa (11). The present study confirmed that both the levels
of MDA and GPx were reversed by CPL treatment. The
result also revealed an increase in the mean FRAP value for
alcohol and CPL treated groups. Ferric reducing antioxidant
potential assay actually detects the level of non-enzymatic
plasma antioxidants It is tempting therefore to speculate the
existence of synergism between enzymatic and non-enzy-
matic antioxidants in preventing oxidative stress. In contrast,
no changes were observed in blood catalase and XO activity.
These results could be due to the short duration of treatment.
Moreover, the results of the study is in concordance with
other studies (12, 13) which reported that GPx is the main
anti-oxidant involved in the removal of hydrogen peroxide
whereas catalase shows a lower affinity for that reactive
oxygen species. The absence of increased XO activity sug-
gests against the involvement of this superoxide generating
enzyme in the development of acute gastric ulcers. The gross
observation of the increasing pH of the stomach secretion
and the alkaline content of CPL extract were interesting find-
ings. It is possible that the extract induced both mucous and
HC03-secretion to protect the stomach lining against alcohol
assault apart from directly neutralizing the stomach acidity.
Drugs used to treat ulcer such as omeprazole, lansoprazole
and famotidine are also known to act via the same mechan-
In conclusion, the CPL aqueous extract offered some pro-
tection against alcohol induced oxidative damage to the gas-
tric mucosa. The antioxidant system present in CPL might
play a protective role against the production of reactive
oxygen species and lipid peroxidation by-products. Work is
Table: Ulcer index and levels of blood oxidant-antioxidant markers in the various treatment groups
C papaya leaf
C papaya leaf
(MDA/µmol/L) 0.099 ± 0.0180.084 ± 0.025 0.133 ± 0.019a
248.06 ± 30.77a
0.102 ± 0.020a,b
243.61 ± 28.92a
GPx (U/mg protein)
210.56 ± 27.188 211.67 ± 30.180
0.054 ± 0.045
2.694 ± 0.310
0.061 ± 0.029
2.720 ± 0.365
0.070 ± 0.022
2.229 ± 0.281a
0.068 ± 0.033
2.475 ± 0.214a,b
0.078 ± 0.0130.080 ± 0.0150.068 ± 0.0370.067 ± 0.029
Index (mm2)00 6235.2 ± 386.33a
993.6 ± 141.384a,b
Data are expressed as mean ± standard deviation. Statistical evaluation of data was performed using SPSS
version 14.0 and the level of significance was evaluated by Duncan’s multiple range test.
ap < 0.05 compared to control and C papaya leaf extract treated groups
bp < 0.05 compared to alcohol treated group
Indran et al
326 Download full-text
in progress to study the molecular mechanism behind the
efficacy of this plant and also to isolate the active com-
ponents of the plant. The present study revealed that CPL
extract is a promising candidate for the development of
phytomedicine against gastric ulcer, and further studies are
needed in this direction.
Financial support by BM 271 Vote (Biomedical Science Di-
vision), Department of Molecular Medicine, University of
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Carica papaya L Leaf Extract