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Ethnobotanical Leaflets 14: 766-73. 2010. Screening of Antimicrobial
Ethanolic Extract of Peristrophe
bicalyculata
O.E. Giwa, O.E. Seyifunmi, B. L. Adewumi, V. T. Adebote
and A.O. Aladejimokun
Department of Science
Laboratory Technology, Rufus Giwa Polytechnic, Owo, E-mail: muyenke2002@yahoo.com Issued: June 1,
2010 Abstract The ethanolic extract from Peritrophe bicalyculata leaves was
evaluated for the presence of phytochemicals and its antimicrobial activity
in vitro against selected bacteria and fungi using the antibiotic gentamycin
as control. The extract showed the presence of secondary metabolites such as
alkaloid, saponin, tannin and steroid. It also inhibited the growth of the
tested microorganisms at different concentrations. However stronger in-vitro
activity was recorded against Staphylococcus aureus, Klebsiella spp,
Pseudomonas aeruginosa, Aspergillus Key words: Phytochemicals, Antimicrobial, Inhibition, Ethnomedicine, In-vitro, Concentration. Introduction
Leafy
vegetables play a very important role in our diet and nutrition since they
are the major sources of not only raw fibers but also essential nutrients,
vitamins and minerals. Some of these vegetables are common in The
importance and awareness of nutrition and medicinal properties of some plant
in public health issues has resulted in the increase demand of knowledge in
the nutrient, phytochemical and antimicrobial properties of food (Chinma and
Igyor, 2007). Green leafy vegetables are rich source of carotene, ascorbic
acid, riboflavin, folic acids and minerals like calcium, iron and phosphorus.
(Fasuyi, 2006). The presence of some phytochemicals determines the antimicrobial
properties of various plants. They give plants its colour, flavour, odour and
are part of the defense system (disease resistance). According to Liu (2004),
phytochemicals are bio actives, non nutrient plants compounds in fruits,
vegetables, grains and other plants food that has been linked to reduce the
risk of major degenerative disease. Report
shows that the greatest sources of these photochemicals are fruits and
vegetables. (Onyeka and Uwambeke, 2007). Most leafy vegetable constitute an
indispensable constituent of human diet in Africa generally and Western part
of This research work was therefore, aimed at determining the presence or otherwise of some phytochemicals and also antimicrobial properties of ethanolic extracts of Peristrophe bicalyculata leaves on selected microorganisms in order to determine its medicinal use. Materials
and Methods Source of
Materials Fresh leaves of Peritrophe bicalyculata were collected from
“Obasoto” in Owo township, Extraction
of Plant Materials
The pulverized fresh leaves (100g) were extracted with 95% ethanol by cold maceration for 24 hours at room temperature (25oC). The extract was filtered and evaporated to dryness over water bath after concentration with rotor vapour to minimal volume. Determination
of alkaloids
A
measured weight of the sample was dispensed into 10% acetic acid solution in
ethanol to form a ratio of 1:10. The mixture was allowed to stand for 4 hours
at 28oC. It was later filtered with filter paper and the filtrate
was treated with drop wise addition of aqueous NH4OH until the
alkaloid was precipitated, this was washed with 10% ammonia solution and
dried in the oven at 80oC. Determination of flavonoids 5g
of the sample was boiled in 50ml of 2M HCl solution for 30 minutes under
reflux. It was allowed to cool, then filtered through filter paper and the
filtrate was treated with equal volume of ethyl acetate. Determination of tannin A
5g portion of the sample was dispensed in 50ml of distilled water and mixed
properly. This was allowed to stand for 30 minutes at 28oC before
it was filtered. 2ml of the plant extract was dispensed into a 50ml
volumetric flask. Similarly, 2ml standard solution and 2ml of distilled water
were put in separate volumetric flask. The reagent was added to each of the
flask, and 2.5ml of saturated Na2CO3 solution was also
added, the total content of the flask was made up to 50ml with distilled
water and incubated at 28oC for 90 minutes. A spectrophotometer
set at 260nm wavelength was used to measure the respective absorbance using
the reagent blank to calibrate the instrument. Determination of Steroid A
measured weight of the sample was dispensed in 100ml freshly distilled water
and homogenized in laboratory blender. This was filtered and was eluted with
normal ammonium hydroxide solution (PH
9). 2ml of the eluate was put into the test tube and mixed with 2ml of
chloroform. 3ml of ice-cold acetic anhydride were added to the mixture in the
flask and 2 drops of concentrated H2SO4 were added to cool.
Standard sterol solution was prepared and spectrophotometer at 420nm was used
to measure the absorbance. Antimicrobial Screening The
crude ethanolic extract of the fresh leaves was screened for antimicrobial
activities against clinically isolates using Agar diffusion steak methods.
The test organisms were prepared by sub culturing them overnight in culture
media and incubated in a freshly prepared nutrient broth at 37oC
for 3 hours. 100mg of the test extract was dissolved into 1ml to give a
concentration of 100mg/ml of the extract. Clinically isolated bacteria (E.
coli, Klebsiella spp, Staphylococcus aureus and Pseudomonas aeruginosa) were
inoculated using steak method. 1ml of prepared extract was then introduced
into 5mm hole in a solidified inoculated agar, bored with a cork borer and
was placed at 540C. Gentamycin, a broad-spectrum antibiotic was
used as standard. Result and Discussion The
presence of alkaloids, tannin, steroid and flavonoid in the plant as shown in
Table1 may be collectively or individually responsible for the observed
antimicrobial activities. This result also corresponds with the results of
phytochemicals of plants and fruit common in the region (Onyeka, and
Uwambeke, 2007). Table
2 shows the result of the antimicrobial potency of crude ethanolic extract of
Peritrophe bicalyculata against some selected microorganisms. The
diameters of the zone of inhibition of this extract were compared with
Gentamycin. The effect of the ethanolic extract of the Peritrophe
bicalyculata was strongly effective against the test bacteria: Staphylococcus
aureus, Klebsiella spp., E. coli, and Pseudomonas aeruginosa, to be
2.1cm, 1.9cm, 2.0cm, 2.1cm zones of inhibition at concentration of 100mg/ml
respectively. The fungi: Aspergillus The
MIC of the extract from the Peritrophe bicalyculata were 90g/ml, 90g/ml, 60g/ml and 60g/ml
for Staphylococcus aureus, Klebsiella spp., E. coli, and Pseudomonas
aeruginosa, respectively and 60g/ml, 90g/ml, 60g/ml for the fungi
isolates; Aspergillus niger, Aspergillus clavatu and Rhizopus stolonifer respectively.
The varied minimum inhibitory concentration revealed that the extract is
highly effective against E. coli, Pseudomonas aeruginosa,
Asperillus This
suggest that the species can be gainfully employed in the production of
antibiotics as the low MICs means that only a small quantity of extract will
be required to inhibit the organisms. The antimicrobial activities shown by Peritrophe
bicalyculata is in line with the previous antimicrobial works on
different plants analyzed in the region (Onyeka, and Uwambeke, 2007). There
is a need for further study to ascertain if the yield in this species will be
increased by using stronger fractionating solvent such as ethyl acetone or
methyl acetone. These solvents have been reported to be more vigorous than
other solvents used in crude extraction of plants (Ajayeioba and Fadare,
2006). Efforts should also be made to quantify the identified phytochemicals. In conclusion, the results from this study have shown the potency
of the plant crude extract on the tested microorganisms, which is indication
of the medicinal value of the plant extract. The extract compared favourably
well with gentamycin that was used as control. TABLE
1.
Alkaloid
+ Saponin
+ Tannin + Steroid
+
+ = Presence of secondary
metabolite - = Absence
of secondary metabolite TABLE
2. Minimum inhibitory concentration (MIC) of ethanolic extracts pertrophe bicalyculata
on selected test isolates in (mg/ml) and the zone of inhitition measure
in centimeter. Zones of inhibition
(cm)
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