Phytochemical Screening and Antibacterial Activity of Tamarindus Indica Pulp Extract
The phytochemical analysis and antibacterial activity of aqueous
pulp extract of Tamarindus indica were studied. The aqueous pulp
extract of this plant was obtained using hot water extraction method.
The antibacterial activity of aqueous pulp extract of this plantwas carried
out against four bacteria; Escherichia coli, Staphylococcus
aureus, Pseudomonas aeruginosa and Salmonella typhi by
disc diffusion method. Phytochemical constituents present in the
extract were found to include saponins (2.2%), alkaloids (4.32%) and glycosides
(1.59%). Aqueous pulp extract of Tamarindus indica showed antibacterial
activity against all the tested bacteria in the order of sensitivity as
Staphylococcus aureus>Escherichia coli>Pseudomonas aeruginosa
with the exception salmonella typhi. The antibacterial activity
of aqueous pulp extract on Staphylococcus aureus was sensitive
at 80, 120, 140, 160 and 180 mg mL-1 of extract with 0.2, 0.3,
0.6, 0.8 and 10.0 mm zones of inhibition while Escherichia coli
revealed 0.2, 0.2, 0.4 and 0.6 mm zones of inhibition at 120, 140, 160
and 180 mg mL-1 of extract, respectively. Pseudomonas aeruginosa
was only sensitive at 140, 160 and 180 mg mL-1 of the extract
with 0.4, 0.6 and 0.8 mm zones of inhibition.
Traditionally, the use of plant preparation as sources of drugs
are based on the experience and superstition passed from generation to
generation, virtually by the word of mouth (Sofowora, 1993). Plants have
provided a source of inspiration of novel drug compounds, as plant derived
medicines have made large contributions to human health and well-being.
Their role is two fold in the development of new drugs: (1) they may become
base for the development of a medicine, i.e., natural blue print of the
development of new drugs or (2) a phytomedicine to be used for the treatment
Tamarindus indica (Linn.), family Fabaceae/Leguminosea (Caesalpiniodae),
is a slow growing, long lived massive fruit tree of the tropics. Although
native to tropical Africa, the tree grows wild through out Sudan and was
so long ago introduced into and adopted in India that it has often been
reported as indigenous there also. In all tropical and near tropical areas,
it is grown as a shade and fruit tree along roadsides, indoor yards and
Medicinal uses of Tamarindus indica are numerous. The fruit extracts
are used as refrigerants in fevers and as laxatives and carminatives alone
or combinations with limejuice, honey, milk, dates spices and camphor.
The pulp is used in digestive, as remedy for biliousness and bile disorders
(Jayaweera, 1981). As an anti scorbutic, it is applied to heal inflammations
and soar throat, mixed with salt to treat rheumatism and administered
to alleviate sunstroke, dasine poisoning and alcoholic intoxication in
Southeast Asia (Morton, 1987).
The pulp is composed of tartaric acid, citric and malic acids, potassium
bitartarate, pectin, gum, water and parenchymatous fiber (Nyadoi and Abdullahi,
2004). It is used to allay thirst, is nutritive and forms useful drinks
given to persons recovering from sickness to keep their bowels regular
(Morton, 1987). Punch made from it in mixture with other beverages is
used to allay scalding urine in West Indies (Morton, 1987). In Mauritius
the Creoles mix the pulp with salt to rheumatism while a decoction from
the bark is used in asthma treatment. The Bengalese uses the pulp in dysentery
treatment and as food (pods boiled or macerated) in food scarce periods.
In Nigeria, particularly in the northwestern part, Tamarindus indica
pulp is popularly employed on a daily basis as a flavor in the production
of local drinks, preservation of food and in the general traditional medicine
practice as a drug conveyor, in combination with other herb for treatment
of various diseases such as indigestion, constipation, fever and inflammation.
In the native practice, Tamarindus indica is applied on inflammations,
used as a gargle for sore throat and mixed with salt as a liniment for
rheumatism, accelerate expulsion, relieve pains, reduce secondary bacterial
infections and promote healing (Fabiyi et al., 1993).
Because of the side effect, resistance and pathogenic microorganism build
against the antibiotics, much recent attention has been paid to extracts
of biologically active component isolated from plant species used in herbal
medicine. Medicinal plants may offer a new source of antibacterial, antifungi
and antiviral activities.
In the present study therefore, Tamarindus indica pulp extract,
were screened for phytochemical constituents and antibacterial activity.
MATERIALS AND METHODS
Tamarindus indica pulp was obtained from the wild of Sokoto south
local government area of Sokoto state, Nigeria. The plant was identified
at Botany unit, Usmanu Danfodiyo University, Sokoto, Nigeria. A voucher
specimen was prepared and deposited in the herbarium of the same institution
for reference as recommended by Kumar et al. (2000).
Preparation of Extract
The aqueous extract of Tamarindus indica was obtained using the
hot water extraction technique in order to stimulate the local procedure
as described by Akinyole and Olorede (2000). Four hundred 400 g soaked
in 2 L of distilled water and boiled for 5 min. This was shaken for 10
min and allowed to cool then filtered. The filtrate was evaporated to
a residue in a drying cabinet. The percentage yield was 25.2%w/w.
The possible presence of saponins and glycosides in the pulp were screened
for according to the procedure as described by Trease and Evans (1986),
while the presence of alkaloids was assayed using the method described
in Sofowora (1993). This was carried out in Biochemistry Department of
Usmanu Danfodiyo University, Sokoto, Nigeria in May 2006.
The following bacterial cultures were used: Escherichia coli,
Staphlococcus aureus, Pseudomonas aeruginosa and Samonella
typhi were obtained from Microbiology Department, Usmanu Danfodiyo
University Teaching Hospital (UDUTH) Sokoto and reidentified according
to the method of Cowas and Steel (1992).
Antibacterial activity of the aqueous extract was determined by the disc
diffusion method as described by Lennette (1985). The microorganisms were
cultured overnight at 35Â°C in nutrient agar. Suspension of the bacteria
with an optical density of McFarlend 0.5 was made in isotonic sodium chloride
Petri dishes with 60 mL of sterile Mueller Hinton agar were seeded with
the appropriate bacterial suspension. Sterile, 6 mm diameter filter paper
disc were impregnated with the extract of different concentration, gently
tapped to remove excess liquid and positioned on seeded plates at 45Â°
opposite each other into each petri dish, respectively. After incubation
for 24 h at 35Â°C, the plates were observed for zones of inhibition
and the diameter of these zones measured in millimeters.
This research was conducted in the Microbiology unit of Biological Science
Department of Usmanu Danfodiyo University, Sokoto, Nigeria in May 2006.
The result of the phytochemical screening of Tamarindus indica
pulp extract qualitatively and quantitatively is shown in Table
1 and 2, respectively. The phytochemical constituents
of the extract included alkaloid (4.32%), saponins (2.2%) and glycosides
(1.59%). Tannins and flavoniod were not detectable at the tested assay
Determination of the inhibition zones by means of the disc diffusion
method (Table 2) shows that the pulp extract exhibited
an antibacterial effect against all the four tested bacterial except Samonella
typhi. Staphylococcus aureus was sensitive at 80,120,
140, 160 and 180 mg mL-1 of extract with 0.2, 0.3, 0.6, 0.8
and 10.0 mm zones of inhibition while Escherichia coli revealed
0.2, 0.2, 0.4 and 0.6 mm zones of inhibition at 120,140, 160 and 180 mg
mL-1 of extract respectively. Pseudomonas aeruginosa was
only sensitive at 140, 160 and 180 mg mL-1 of the extract with
0.4, 0.6 and 0.8 mm zones of inhibition.
||Phytochemical screening of Tamarindus indica pulp
|+++: Represents high concentration; +: Represents low
concentration; -: Represents constituents not detectable using the
specified assay method
||Antibacterial activity of Tamarindus indica pulp extract
In literature it has been indicated that medicinal plants are the
backbone of traditional medicine (Fransworth, 1994) and the antibacterial
activity of plant extract is due to different chemical agent in the extract,
which were classified as active antimicrobial compounds (Rojas et al.,
1992). Plants have the capacity to synthesize a diverse array of chemicals
and understanding how phytochemicals function in plants may further our
understanding of the mechanisms by which they benefit humans. In plants,
these compounds function to attract beneficial and repel harmful organisms,
serve as photoprotectants and respond to environmental changes. In humans,
they can have complementary and overlapping actions, including antioxidant
effects, modulation of detoxification enzymes, stimulation of the immune
system, reduction of inflammation, modulation of steroid metabolism and
antibacterial and antiviral effects (Johanna, 2003).
In the present study, aqueous pulp extract of T. indica tested
positive for the presence of alkaloids (4.32%), saponins (2.2%) and glycosides
(1.59%). Alkaloid is a plant-derived compound that is toxic or physiologically
active, contains nitrogen in a heterocyclic ring with complex structure
and is of limited distribution in the plant kingdom. Alkaloids are formed
as metabolic by-products and have been reported to be responsible for
the antibacterial activity (Doughari, 2006). This is consistent with the
reports of De et al. (1999) of which 35 different Indian spices
and herbs indicated that Tamarindus indica pulp among others, had
potent antimicrobial activities against the test organisms Bacillus
subtilis, Escherichia coli and Saccharomyces cerevisiae.
Many phytochemicals are present in plants as glycosides (with a sugar
moiety attached). Generally, glycosides are nonvolatile and lack fragrance.
Cleaving the glycosidic bond yields the aglycon, which itself may be volatile
and fragrant. Glycosides serve as defense mechanisms against predation
by many microorganisms, insects and herbivores (De et al., 1999).
This may therefore explain the demonstration of antimicrobial activity
by the stem bark and leaf extracts of Tamarindus indica (Doughari,
The low percentage yield of 25.2% suggest that the plant Tamarindus
indica contains fibers which will turn out to be residue after extraction
while the average pH is 1.27 indicating the acidic nature of the extract.
This acidity could be as a result of the presence of hetero-organic acids
in Tamarindus indica pulp as reported by Morton (1987). The acidic
nature and the antibacterial activity of Tamarindus indica obtained
from the result suggests its usefulness in preservation of food items
against contamination by E. coli and other gram negative rods as
well as in the management of cases of food infection by this pathogens
The aqueous pulp extract of Tamarindus indica exhibited increasing
degree of antibacterial activities against the tested microorganismsin
the following order of sensitivity; Staphylococcus aureus >Escherichia
coli>Pseudomonas aeruginosa. The sensitivity of E. coli
to Tamarindus indica is consistent with the observation that E.
coli and a few other gram negative bacteria are affected by some plant
extract (Chlabra et al., 1981). This inhibitory effect may be as
a result of the change in pH and chemical constituent(s) of the aqueous
pulp extract of this plant. The mechanism of action of these phytochemicals
may be via lysing the cell, increasing permeability of the cell wall and
membrane, inhibition of protein and DNA synthesis and or by inhibiting
the transport of nutrient across the cell wall or membrane (Stewart and
Beswick, 1979). This inhibitory effect of the extract on the growth of
these microorganisms could be attributed to the presence of some phytochemicals
that were found present in the plant extract. Saponins has detergent properties
and serve as lytic agent and exhibits anti inflammatory properties (Lewis
and Elvin-Lewis, 1977) while alkaloids and glycosides among functions
with the aid of their defense mechanism act as phytoprotective agent against
invading microorganism. The demonstration of antibacterial activity against
both gram positive and gram negative bacteria by this plant may be indicative
of the presence of broad spectrum antibiotic compounds (Doughari, 2006).
The success of the ethnobotanical approach to drugs discovery can no
longer be questioned. Historical and current discoveries demonstrate its
power (Cox, 1994). A complete study conducted with the purpose of finding
these chemicals is worthwhile. The optimal effectiveness of a medicinal
plant may not be due to one main active constituent, but may be due to
the combine action of different compounds originally in the plant (Bai,
From this study we can conclude that this is a promising plant and the
result confirms the use of this plant in traditional medicine for the
treatment of infections.
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