Phytochemical screening and antimicrobial activity of Sesbania sesban (L.) Merr

Abstract

Sesbania sesban (L.) Merr. is an erect, branched small tree up to 6 m tall with soft wood and paripinnate leaves. Flowers are yellow with brown streaks on the corolla. Fruits are sub cylindrical and shortly beaked. Seeds are green or brown and usually mottled. The plant is used as astringent, anti-inflammatory, carminative, demulcent, anthelmintic and antimicrobial. The phytochemical analysis of the methanol and ethanol extracts of both stem and root of Sesbania sesban revealed the presence of alkaloids, carbohydrates, proteins, phytosterol, phenol, flavonoids, fixed oil and gum. The leaf extract showed the presence of alkaloids, carbohydrates, protein, phytosterol, flavonoids and fixed oil. In vitro biological screening effects of the methanol stem extract was tested against ten bacterial species and five fungal species. Highly significant activity was observed against the bacteria Erwinia amylovora followed by Escherichia coli. In the case of fungi Curvularia lunata and Fusarium oxysporum were inhibited completely.

Full text

Research Article
PHYTOCHEMICAL SCREENING AND ANTIMICROBIAL ACTIVITY OF SESBANIA SESBAN (L.)
MERR.
T. MYTHILI1* AND R. RAVINDHRAN2
1 Department of Plant Biology and Plant Biotechnology, Ethiraj College for Women, Chennai-8, 2 Department of Plant Biology and
Biotechnology, Loyola College, Chennai-34.Email: mythili22.t@gmail.com
Received:2 August 2012, Revised and Accepted:7 September 2012
ABSTRACT
Sesbania sesban (L.) Merr. is an erect, branched small tree up to 6 m tall with soft wood and paripinnate leaves. Flowers are yellow with brown
streaks on the corolla. Fruits are sub cylindrical and shortly beaked. Seeds are green or brown and usually mottled. The plan t is used as astringent,
anti-inflammatory, carminative, demulcent, anthelmintic and antimicrobial. The phytochemical analysis of the methanol and ethanol extracts of
both stem and root of Sesbania sesban revealed the presence of alkaloids, carbohydrates, proteins, phytosterol, phenol, flavonoids, fixed oil and gum.
The leaf extract showed the presence of alkaloids, carbohydrates, protein, phytosterol, flavonoids and fixed oil. In vitro biological screening effects
of the methanol stem extract was tested against ten bacterial species and five fungal species. Highly significant activity was observed against the
bacteria Erwinia amylovora followed by Escherichia coli. In the case of fungi Curvularia lunata and Fusarium oxysporum were inhibited completely.
Keywords: Sesbania sesban, alkaloids, phytosterol, phenol, flavonoids, methanol stem extract.
INTRODUCTION
Medicinal plants are nature’s gift to human beings for disease free
healthy life. In India, different parts of several medicinal plants or
their extracts are used for the treatment of various diseases. More
than a hundred species of therapeutically important higher plants
are listed and described in ancient Indian treatise possessing
antimicrobial activity1.
According to World Health Organization (WHO), traditional
medicine is estimated to be used by 80% of the population of most
developing countries. These plant-based medicines are used for
primary health care needs2. Although plants are unique in their
activities, it has also been found that a particular plant may be used
by different tribes or countries for different ailments. This shows
that plants possess a wide range of healing powers which are
attributed to their chemical composition. Despite the wealth of
human experience and folklore concerning the medicinal uses of
plants, proper scientific investigation has only been applied to a
small fraction of the world's plants3. Tamil Nadu is under strategic
geographical location and possesses an invaluable treasure of herbal
medicinal plants holding a major share in cultivation and export of
more than fifty medicinal plants species. Medicinal plants are
cultivated in Tamil Nadu in isolated patches each being grown in
favourable soil and agro climatic region4.
The medicinal value of plants lies in some chemical substances or
group of compounds that produce a definite physiological action in
the human body. These chemical substances are called secondary
metabolites. The most important of these bioactive groups of plants
are alkaloids, terpenoids, steroids, flavonoids, tannins and phenolic
compounds5.
Sesbania sesban Linn. is a soft, slightly woody, 1-6 m tall perennial
nitrogen fixing small tree. The leaves are compound 12-18 cm long
made up of 6-27 pairs of leaflets. The raceme has 2-20 flowers which
are yellow with purple or brown streaks on the corolla. Pods are
subcylindrical, straight or slightly curved up to 30 cm long and 5 mm
wide containing 10- 50 seeds. The plant is used as carminative,
anthelmintic, astringent, anti-inflammatory, antimicrobial,
antifertility, demulcent and purgative. It is also given as a medicine
against fever, ulcers etc.,6
MATERIALS AND METHODS
Plant materials
Different plant parts (leaf, stem and root) of S.sesban were collected
and the authenticity of the plant was confirmed by the Botanical
Survey of India, Coimbatore, India.
Preparation of extracts
The plants were cleaned, washed, shade dried and powdered for the
phytochemical study. The parts used were leaf, stem and root.
Extraction of the plant parts were done with different solvents based
on the polarity of the solvents. The solvents used were hexane,
chloroform, methanol, ethanol and water. The extract of the leaf,
stem and root were obtained through the cold percolation method.
The powdered plant material was weighed and then soaked in
hexane for 72 hrs. Then the extract was taken by filtering the
content. The same procedure was repeated again and the extract
was collected. The extracts were pooled together and concentrated
on a water bath by keeping the temperature below the boiling point
of the solvent used. The concentrated extract was kept in the
desiccator for further evaporation of the solvent. Then the extract
was weighed and the yield was recorded. The same procedure was
repeated for all the solvents. The extracts taken were used for
further phytochemical analyses of the plant. The standard
qualitative phytochemical tests given for the respective compounds
were performed.
Qualitative phytochemical analysis
The concentrated extracts were subjected to qualitative test for the
identification of various phytochemical constituents as per standard
procedures7, 8, 9, 10. Based on the results obtained in the qualitative
phytochemical analysis, the methanol extract of the stem was taken
for antimicrobial study.
Antibacterial assay
The antibacterial assay was performed by agar well diffusion
method. The nutrient agar was inoculated with 100 μl of the
inoculum (106 CFU/ml) and poured into the Petri plate. A well was
prepared in the plates with the help of a cork-borer (6 mm). About
50 μl of the extract (100, 250 and 500 µg/ml) was dispensed into the
well. The flavonoid quercetin 100 µg/ml was used as the standard.
The plates were incubated overnight at 37ºC. For each bacterial
strain, bacitracin 100 µg/ml as positive control and pure solvent
(methanol) as the negative control were maintained. The diameters
of the inhibition zones were measured in mm. The bacterial species
used were Staphylococcus aureus (ATCC 25923), Escherichia coli
(ATCC 25922), Salmonella typhi (MTCC 733), Enterococcus faecalis
(ATCC 29212), Erwinia amylovora (MTCC 2760), Proteus vulgaris
(MTCC 1771), Pseudomonas aeruginosa (MTCC 424), Klebsiella
pneumoniae (ATCC 15380), Shigella dysenteriae (MTCC 5151) and
Bacillus subtilis (ATCC 441).
Asian Journal of Pharmaceutical and Clinical Research
Vol 5, Issue 4, 2012 ISSN - 0974-2441
Vol. 4, Issue 3, 2011
ISSN - 0974-2441
Academic Sciences

Mythili et al.
Asian J Pharm Clin Res, Vol 5, Issue 4, 2012, 179-182
180
sAntifungal activity
The antifungal activity was performed by Poison plate method.
Different concentrations (100, 250, 500 and 1000 µg/ml) of the
methanol extract was added to the potato dextrose agar and poured
into the petriplate. The flavonoid quercetin 100 µg/ml was used as
the standard. Carbendazim 100 µg/ml was used as positive control
and pure solvent (methanol) as the negative control. A disc (6 mm in
diameter) of actively growing mycelium of the test fungi was
obtained using a sterile cork borer. These fungal discs were placed
on the potato dextrose agar which was mixed with the extract. The
plates were maintained at a temperature of 28±2°C. After 48 hrs, the
plates were observed and the diameter of the fungal growth was
measured. The zone of inhibition was measured for pathogenicity of
the extract. Fungal species taken for study were Aspergillus
fumigatus, Colletotrichum gloeosporioides, Curvularia lunata,
Fusarium oxysporum and Verticillium glaucum.
RESULTS AND DISCUSSION
The phytochemical test of the crude methanol and ethanol extracts
of both stem and root of Sesbania sesban revealed the presence of
alkaloids, carbohydrates, protein, phytosterol, phenol, flavonoids,
fixed oil and gum. Saponin was found only in the aqueous extract of
the plant. These metabolites are similar to those found in F.
sycomorus11, 12. The alkaloids, tannins and flavonoids are known to
have curative activity against several pathogens and therefore could
be used for the treatment of various illnesses13, 14.
Table 1: Qualitative Phytochemical analysis of Sesbania sesban
Tests
Leaf
Stem
Root
H
C
M
E
A
H
C
M
E
A
H
C
M
E
A
Alkaloids
Carbohydrates
Protein
Phytosterol
Phenol
Flavonoids
Saponin
Fixed Oil
Gum
+
+
+
++
++
+
++
++
+
+
+
++
++
++
+
-
-
+
+
+
-
-
+
+
+
-
-
+
+
-
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
-
-
+
+
+
-
-
+
+
-
-
-
-
-
-
+
+
+
+
+
-
+
+
+
+
+
+
+
+
+
-
-
-
-
+
-
-
-
-
+
-
-
-
-
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
-
+
-
+
+
+
+
+
+
-
+
+
+
+
+
H- hexane, C- chloroform, M- methanol, E- ethanol, A- aqueous
++ = strong, + = present, - = absent
Table 2: Antibacterial activity of methanol stem extract of Sesbania sesban (in mm)
Bacteria
Extract
100 µg/ml
Extract
250 µg/ml
Extract
500 µg/ml
Extract
1000 µg/ml
Quercetin 100 µg/ml
Bacitracin 100 µg/ml
B.subtilis
8.75±0.43
9.25±0.43
15.5±0.50
9.75±1.0
15.0±0.71
8.75±0.43
E.coli
8.5±0.50
16.0±1.0
9.25±0.43
9.0
12.25±1.48
8.75±0.43
E.faecalis
9.25±0.43
12.75±0.43
9.0
-
12.25±0.43
-
E.amylovora
11.25±1.48
17.25±1.30
-
9.75±1.30
15.25±0.83
9.75±0.83
P.vulgaris
-
-
-
-
-
-
P.aeruginosa
8.25±0.43
7.5±1.12
9.5±0.87
7.5±0.50
12.25±0.43
9.0±0.71
K.pneumoniae
8.5±1.30
-
8.0±1.30
-
19.25±0.83
9.0
S.typhi
-
-
-
-
14.25±0.83
-
S.dysenteriae
-
-
10.25±1.30
10.0±2.0
10.0±1.0
10.0±1.0
S.aureus
9.5±0.50
13.0±0.71
8.5±0.50
-
14.25±0.83
9.5±0.87
Values are mean inhibition zone (mm) ± S.D of four replicates
Table 3 : Antifungal activity of methanol stem extract of Sesbania sesban (in mm)
Fungi
Extract
100 µg/ml
Extract
250 µg/ml
Extract
500 µg/ml
Extract
1000 µg/ml
Quercetin 100 µg/ml
Carbendazim 100 µg/ml
Aspergillus fumigatus
-
-
10.5±5.76
-
27.75±5.49
27.75±5.49
Colletotrichum gloeosporioides
10.75±6.09
-
11.0±5.09
9.25±6.37
14.25±5.11
19.75±5.58
Curvularia lunata
12.75±3.63
10.5±4.03
18.75±2.94
15.75±2.48
18.75±2.94
18.75±2.94
Fusarium oxysporum
23.25±5.62
13.75±5.53
23.25±5.62
23.25±5.62
23.25±5.62
23.25±5.62
Verticillium glaucum
10.5±2.17
-
14.75±2.16
2.5±0.5
29.75±1.08
31.75±1.63
Values are mean (mm) ± S.D of four replicates
Phytochemical analysis is the characterization of an active principle
responsible for some toxic or beneficial effect shown by a crude
plant extract. Alkaloids are heterogeneous group compounds which
contain one or more nitrogen atom in acyclic system. These are
widely used for medicinal purposes and have positive or negative
effects to human beings15. Alkaloids are reported to have analgesic,
anti-inflammatory function and help to alleviate pain, develop
resistance against diseases and endurance against stress16. A better
precipitation of alkaloids was obtained in the methanol and ethanol
extracts of both stem and root extracts of Sesbania sesban. The result
coincides with the view of Jain et al., (2004) who found high degree
of alkaloid precipitation in the methanol extract of Cocculus
hirsutus17.
Harborne (1973) qualified flavonoids as being probably the most
useful class of secondary plant constituents from a systematic point
of view7. The flavonoids are the compounds structurally derived
from the parent substance flavone, and contain conjugated aromatic
systems15. Flavonoids have been referred to as nature’s biological
compound because of their inherent ability to modify the reaction
taking place in the body due to allergies, virus and carcinogens. They
show anti-inflammatory, antimicrobial and anticancer activity18.
Flavonoids are found in chloroform, methanol and ethanol extracts
of leaves, stem and root extracts of S.sesban and show different
degree of precipitation. Highest degree of colour development was
observed in the methanol extracts of leaves followed by the stem of
S.sesban. This result correlates with the result of Siciliano et al.
(2004) who detected and quantified eight flavonoids, three C-

Mythili et al.
Asian J Pharm Clin Res, Vol 5, Issue 4, 2012, 179-182
181
glycosyl and five O-glycosyl flavones in roots, leaves, stems and
fruits of Sechium edule19.
Phenols are reported as antitumour agents and exhibit antioxidant
properties20. The methanol and ethanol extracts of stem and leaf of
S.sesban showed a better precipitation of phenolic content. Similar
results were reported for methanol leaf extracts of oxalis
corniculata21.
Phytosterols were found to be present in all the five extracts of the
plant parts. Sterols and triterpenes are based on the cyclopentane
perhydrophenanthrene ring system. In recent years, an increasing
number of these compounds have been detected in plant tissues.
These phytosterols are probably ubiquitous in occurrence in higher
plants and occur as both free and as simple glucosides15. Similar
observations are made from the plant parts of Ichnocarpus
frutescens22. Today, natural products derived from plants are being
tested for the presence of new drugs with new modes of
pharmacological action, utilizing the special feature of higher plants
to produce a large number of secondary metabolites23.
Highly significant degree of activity was observed against the test
bacteria Erwinia amylovora with 17.25 mm in diameter followed by
Escherichia coli with 16 mm in diameter at 250 µg/ml of the extract.
The carbon tetrachloride partitionate of the methanol leaf extract of
S.sesban showed the strongest inhibitory activity against E. coli
having the zone size 12 mm24. In most of the bacteria examined, a
better zone of inhibition was obtained at 250µg/ml and 500 µg/ml
of the extract. When compared to the standard flavonoid quercetin,
the plant extract showed a substantial amount of inhibition in the
case of Bacillus subtilis (15.5 mm), Escherichia coli (16 mm),
Enterococcus faecalis (12.75 mm), Erwinia amylovora (17.25mm)
and Shigella dysenteriae (10.25 mm). A fluctuating trend of
inhibition zone was found against some pathogens in the analysis.
Similar fluctuation trend of inhibition zone was reported by Kunjal
Bhatt et al., (2003) and Uma and Sasikumar (2005)25, 26. This may be
due to the fact that at higher concentrations, the rate of diffusion
may perhaps be varied and hence, it might not be available to react
with the microorganisms.
Plants are important source of potentially useful structures for the
development of new chemotherapeutic agents. The first step
towards this goal is the in vitro antibacterial activity assay and in the
recent years several reports available on the antibacterial activity of
plant extracts on human pathogenic bacteria27. The beneficial effects
of treatment can be achieved with the stem extract of S.sesban for
various bacterial infectious diseases like pneumonia, diarrohea,
urinary tract infection and even some skin disease. The broad
antibacterial activities could be as a result of the plant secondary
metabolites like alkaloids, flavonoids, tannins, phytosterols etc.,
present in the extracts. Usman and Osuji (2007) reported that
tannins had been widely used topically to sprains, bruises and
superficial wounds as such, it could be probable that tannins and
other plant phenols from this extract were responsible for these
broad activities14.
In the case of Aspergillus fumigatus, Curvularia lunata, and
Verticillium glaucum a higher degree of inhibition was obtained with
500 µg/ml of the methanol stem extract. Fusarium oxysporum and
Curvularia lunata were inhibited completely at 100µg/ml and 500
µg/ml of the extract. Carbon tetrachloride and chloroform soluble
fraction of the methanol extract of Sesbania sesban leaf strongly
inhibited the growth of A. niger24. The methanol extract of the plants
Grewia arborea, Moringa heterophylla, Strychnos nuxvomica etc.
exhibited varying degrees of inhibition activity against the fungi28.
Some of these observations have helped in identifying the active
principle responsible for such activities and in developing drugs for
the therapeutic use in human beings.
CONCLUSION
Phytochemical study showed the presence of phytochemicals such
as alkaloids, flavonoids, phenols and phytosterols in Sesbania sesban
which might be responsible for their therapeutic effects. It further
reflects a possibility for the development of many more novel
chemotherapeutic agents or templates from the plant which in
future may serve for the production of improved therapeutic plant
based drugs. In conclusion, the stem extract of Sesbania sesban
possess a broad spectrum of activity against a panel of bacteria and
fungi responsible for the most common bacterial and fungal
diseases.
ACKNOWLEDGEMENTS
T.M thanks Dr. Shyamala Kanakarajan, HOD, Dept. of Plant Biology
and Plant Biotechnology, Ethiraj College for Women, for her support
and providing lab facilities.
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