PHYTOCHEMICAL AND ANTIMICROBIAL EVALUATION OF LEAF AND SEED OF
MORINGA OLIFERA EXTRACTS.
A. J. Akinyeye (e –mail bayotwo@yahoo.com, Tel- 08038625445), E.O. Solanke (e-mail
olatoyesolanke@yahoo.com,
Tel-08032449953)
and
I.O.
Adebiyi
(e-mail
itunuadebiyi@yahoo.com, Tel- 07012726041)
1DEPARTMENT
OF BIOLOGICAL SCIENCES IGBINEDION UNIVERSITY OKADA,
EDO STATE, NIGERIA.
Abstact
In recent times, the use of plants as a source of vital compounds to combat microbial infections
has gained prominence. The necessity to search for plant-based antimicrobials is increasing due
to high cost, reduced efficacy and increased resistance to conventional medicines. This study
analyzed the phytochemical composition of moringa olifera, and antimicrobial potential of its
methanol and hexane extracts on Escherichia coli, Klebsiella pneumonia, Pseudomonas
aeuriginosa and Candida albicans, using antimicrobial screening techniques. Phytochemical
analysis revealed the presence of alkaloids, glycosides, flavonoids, steroids, saponins and
tannins. The methanol extracts of the leaf of this plant at a concentration of 1040mg/ml exhibited
antimicrobial activities against all the microorganisms. The hexane leaf extract however
inhibited all the microorganisms in all concentration except P aeuriginosa. The methanol
extracts generally showed more antimicrobial effects compared to the hexane extracts. This may
be due to alkaloid and saponins being largely present in the methanol leaf extract. The variations
in the presence of the phytochemicals may also be due to the choice of the solvent used in the
extraction, methanol is a polar solvent while hexane is a non polar. The age of the plant was also
found to have significant effect on the phytochemicals present and thus on the antimicrobial
properties.
KEY Word: Phytochemical, Antimicrobial, Evaluation, Moringa olifera
INTRODUCTION
In Africa and other continents of the world, phytomedicines have been used since time
immemorial to treat various ailments long before the introduction of modern medicine. Herbal
medicines are still widely used in many parts of the world especially in areas where people do
not have access to modern medicines (Hoareau and Da Silva, 1999; Ajibade et al., 2005).
Moreover, in most African countries where herbal medicines are still heavily relied upon because
of the high cost of chemotherapeutic drugs, there is a need for scientific research to determine
the biological activities of medicinal plants. The findings obtained from such research may lead
to the validation of traditionally used and medicinally important plants which will consequently
enable full usage of the properties of these plants (Adde-Mensah, 1992).
Moringa oleifera is a highly valued plant of the Moringaceae family. It is a fast growing
plant widely available in tropics and subtropics with much economic importance for industrial
and medicinal uses. Moringa oleifera, an important medicinal plant is one of the most widely
cultivated species. It is highly valued from time immemorial because of its vast medicinal
properties. In the last few decades, there has been an exponential growth in the field of herbal
medicine. It is getting popularized in developing and developed countries owing to its natural
efficacy and lesser side effects (Brahmachari, 2001).
Also, nutraceutical and pharmaceuticals beneficial properties of different parts of the
Moringaceae plants have different pharmacological actions and toxicity profiles, which have not
yet been completely elucidated (Chinmoy, 2007). For example, leaves of Moringa species have
been traditionally reported to have various biological activities, including antitumoural,
antioxidant,
anti-inflammatory/
diuretic,
antihepatotoxic
properties,
hypotensive,
hypocholesterolemic and hypoglycemic actions (Sreelatha and Padma, 2010). The roots, flowers,
gum and seeds are extensively used as antidiabetic and for treating inflammation, cardiovascular
action, liver diseases, hematological, hepatic and renal function (Mazumder et al., 1999).
Caceres et al., (1992) reported anti-inflammatory activity from the hot water infusions of
flowers, leaves, roots, seeds and stalks or bark of M oleifera using carrageenan-induced hind paw
edema in rats. On the other hand, Moringa species' leaves, fruits and seeds have been reported as
rich sources of protein, essential elements (Calcium, Magnesium, Potassium and Iron and
vitamins (vitamins A, C and E) (Ramachandran et al., 1980; Fuglie, 1999).
In recent times, the use of plants as a source of novel compounds to combat microbial
infections has gained prominence. The necessity to search for plant-based antimicrobials is
increasing due to high cost, reduced efficacy and increased resistance to conventional medicine
(Sankar et al., 2012). In developing countries, herbal medicines play an important role in primary
health care, especially where coverage of health care service is limited. This work is aimed at
finding the phytochemical and antimicrobial activity of the leaf and seed extract of Moringa
oleifera.
Materials and Methods
The research was conducted between February and April, 2013 at Igbinedion University
Microbiology Laboratory, Okada, Edo State, Nigeria. Okada is the headquarters of Ovia NorthEast Local Government of Edo state.
Collection and Identification of Moringa Oleifera
The plant was identified at Lucado Horticultures, Federal University of Technology,
FUTA road, Akure, Ondo State, where the seeds and leaves were also obtained from. The age of
the plant was estimated at about a year and six months old.
Extraction
Each leaf was destalked and air-dried at average room temperature. Continuous turning
of the leaves was done to avert fungal growth for two weeks. They were kept away from high
temperatures and direct sun light to avoid destroying active compounds. The pods containing the
seeds were also dried at room temperature. After about two weeks, the pods opened up, exposing
the seeds. The leaves and the seeds were reduced to fine powder using mortar and pestle. The
fine powder of the leaves weighed 19.25g while that of the seeds weighed 26.40g. They were
measured using a Scout Pro digital weighing scale.
The soxhlet extraction method (continuous/ successive extraction) was used. The
pulverized plant sample (19.25g) of the leaves of Moringa oleifera was filled into the sample
thimble and placed in the inner of the soxhlet apparatus. The soxhlet was fitted at the bottom to a
round bottom flask of appropriate size containing the solvent N- hexane (BDH, England) and
was fitted on top to a reflux condenser. The solvent (n-hexane) was gently heated and the vapour
passed up through the tube and condensed by the condenser back into the thimble to slowly fill
the body of the soxhlet. When the solvent reached the top of the tube, it is siphoned over into the
flask and removed the portion of the substance which it had extracted in the thimble. The process
was reheated automatically until complete extraction was effected. This process was further
repeated for the seed sample (26.40g) with n- hexane. Both sample (seed and leaves) already
extracted with n- hexane was further re- extracted in soxhlet apparatus with methanol solvent
(JHD, China) till complete extraction was attained. The filtrates extractions were taken in
previously weighed evaporating Petri-dishes and a rotary vacuum evaporator was used to remove
the excess solvents. After the complete evaporation, the weight of the extracts was recorded and
then labelled. The extractions stored separately at 4oC in amber coloured airtight bottles.
Phytochemical Screening
Phytochemical analysis was performed using standard procedure prescribed by Sofowora
(1993), Trease and Evans (1989) and Odebiyi and Sofowora (1978).
Collection and Confirmation of Isolates.
The pure culture of microorganisms used for the evaluation of the antimicrobial potential
of the leaves and seed extracts of Moringa oleifera are Escherichia coli, Staphylococcus aureus,
Klebsiella pneumoniae and Candida albicans. The isolates were all locally isolated pure cultures
obtained from the Medical Microbiology Laboratory of Igbinedion University Teaching
Hospital, Okada. The isolates were identified using various standard biochemical tests described
by Olutiola et al., (1991). All bacterial isolates were maintained on nutrient agar slants and
fungal isolates on Potato dextrose agar at a temperature of 4°C. The isolates were confirmed
using morphological and biochemical examination. The morphological examination include,
culture of microorganism and Gram staining test. Biochemical Tests to include Tube coagulase
test, Catalase test, Oxidase test, Urease test, Indole test, Methyl red test, Citrate test, Vogues
proskauer test, Triple sugar iron slant test, Germ tube (for fungi) and Carbohydrate fermentation
test. Identification of the bacterial isolates was accomplished by comparing the characteristics of
the cultures with that of known data.
Standardization of Microorganisms
The microorganisms were inoculated on petri dishes from the slant bottles and incubated
overnight. For each microorganism, culture on the plates was inoculated into 9mls of nutrient
broth to subculture. The bottles were not tightly shut to allow the aerobic organisms grow. They
were incubated overnight. Normal saline was gradually added to 1ml of the subculture and
compared to the Mc Farland standards to make 0.5 Mc Farland standards.
0.5 Mc Farland standard = 1.5 X 108 cfu/ml
1 Mc Farland standard = 3.0 X 108 cfu/ml
1.5 Mc Farland standard = 6.0 X 108 cfu/ml
Sterility test of Moringa Oleifera Extracts
1ml of the extract were each introduced into the nutrient agar growth media and
incubated for 24 hours at 370C. The absence of growth of microorganisms confirmed its sterility.
Susceptibility test on test Organisms with the Extracts.
Antimicrobial activity of the aqueous, hexane and methanol extracts of the leaves and
seeds and was assayed using the agar well diffusion method. The molten sterile agar (20mls) was
poured into each of the sterile petridishes and allowed to set. The petridishes were streaked with
the 0.5 Mc Farland standard of each of the microorganism. A sterile cork borer was used to bore
five equidistant wells into the agar plates. Two of the wells were for the positive control
(0.4mg/ml gentamicin for bacteria and 150mg/ml fluconazole for the fungi), two were for the test
extracts and one for the negative control (hexane/methanol). 100µL of the hexane extracts of the
Moringa oleifera leaf were introduced into the appropriate well using separate plates for each of
the 7 concentration of the extracts, as well as 100µL each of the positive and negative control.
The plates are incubated for 24 hours at 37oC. The relative susceptibility of the microorganisms
in the various extracts was indicated by clear zones of growth inhibition around the well. This
was repeated for the methanol extract of leaf, hexane extract of seed and the methanol seed
extracts. The zones of inhibition were then measured in millimeter. The above method was
carried out in triplicates and the mean of the triplicate results was taken.
Determination of Minimum Inhibitory Concentration (MIC)
The MIC is the lowest concentration of the extract at which growth of microorganism is
inhibited. 0.2ml of each of the concentration of the extract was added to 1.8ml of nutrient broth.
The microorganisms were inoculated into the mixture. Positive controls were prepared using
0.4mg/ml of gentamicin in place of the extract. Hexane was used as the negative control for the
hexane extracts while methanol was used for the methanol extracts. The tubes were incubated
and observed after 24 hours. The MIC was taken as the lowest concentration that prevented
bacterial growth.
Results
Percentage Yield of Extraction
The percentage yield of the extract is shown in table 1. It indicates that methanol gives the
maximum yield for the seed (25.19%) and hexane gives the maximum yield for leaf at 25.19%.
% Yield =
Table 1: Percentage yield and appearance of the crude extracts of Moringa oleifera
Plant Part
Extract
Percentage Yield
Appearance of Crude
Extract
Seed
Hexane
17.27%
Light green liquid
Methanol
25.19%
Brown oily liquid
Hexane
25.19%
Dark green solid
Methanol
23.84%
Dark green liquid
Leaf
Phytochemical Analysis
The Phytochemical screening of the leaf and seed of Moringa oleifera revealed the presence of
the different phytochemical components summarized in table 2. The seed and leaf of Moringa
oleifera contained a number of phytochemicals such as alkaloids, glycerides, flavonoids,
steroids, terpenoids, saponins and tannins. Flavonoids were largely present in both the hexane
and methanol seed extract; tannins were absent in the hexane extracts of the leaves and seeds;
steroids were largely present in all but the methanol leaf extracts; glycosides were also largely
present in the methanol extracts of seed and leaves; terpenoids were absent in all the extracts.
The following were largely present in the methanol extracts of the leaves: alkaloids, saponins,
reducing sugars, carbohydrates, eugenol and glycosides. These data corroborated the findings of
other authors where these compounds exhibited antimicrobial activities (Sato et al., 2004;
Cushine and Lamb, 2009).
Table 2: Phytochemical Analysis of the Hexane and Methanol Extracts of Moringa oleifera Leaf
and Seed.
Phytochemicals
Leaf
Seed
Hexane
Methanol
Hexane
Methanol
Flavonoid
+
+
++
++
Alkaloid
+
++
+
+
Tannin
-
+
-
+
Phenolics
+
-
+
-
Steroids
++
+
++
++
Saponins
+
++
+
+
Reducing sugars
+
++
+
+
Carbohydrate
+
++
+
+
Eugenol
+
++
++
+
Terpenoids
-
-
-
-
Glycosides
+
++
+
++
Keys: - = absent; + = slightly present; ++ = largely present
Antimicrobial Activity Assay
The antibacterial activity of the hexane and methanol extracts was investigated using agar well
diffusion method, against the selected human pathogens such as Escherichia coli, Pseudomonas
aeroginosa, Klebsiella pneumoniae and Candida albicans. All the examined extracts showed
varying degrees of antibacterial and antifungal activities against the tested organisms. The
maximum mean zone of inhibition was exhibited by the methanol leaf extract (25.5mm at
1040mg/ml in Table 3). Of all the extracts, Moringa oleifera leaf extracts has the highest
antimicrobial value with highest antibacterial activity against the bacteria tested and the highest
antifungal activity against the fungus tested (Table 3-6). This suggests that Moringa oleifera leaf
extract has higher potency antimicrobial activity than the seed (Table 3-6). The hexane extract of
the seed showed no inhibition against Escherichia coli, Klebsiella pneumonia and Pneumoniae
aeruginosa at all concentrations (Table 6).
Table 3: Antimicrobial Activity assay of Methanol Leaf Extracts of Moringa oleifera
Microorganisms Mean Zones of Inhibition at
Concentration of the Extract(mm)
various Positive
control
Negative
control
0
0
0
0
0
0
0
0
0
0
0
0
moderately sensitive,
0
10.5
11.5
15
10- 20
25.5 27.5
18.5 18
15
19
22
=sensitive, 20
Methanol
Fluconazole (150mg/ml)
Gentamicin(0.4mg/ml)
1040mg/ml
520mg/ml
260mg/ml
130mg/ml
65mg/ml
32.5mg/ml
16.25mg/ml
E coli
0
0
P aeruginosa
0
0
K pnuemoniae
0
0
C albicans
0
0
Key: 0 = No Inhibition, 0 -10 =
0
0
0
20.5 0
and above =very
sensitive.
Table 4: Antimicrobial Activity assay of Hexane Leaf Extracts of Moringa oleifera
Eschericia coli
0
0
P aeruginosa
0
0
K pnuemoniae
0
0
C albicans
0
0
Key: 0 = No Inhibition, 0 -10 =
0
0
0
0
0
0
0
0
0
0
0
0
moderately sensitive,
0
0
0
0
10- 20
17
29
0
25.5
22.5 23.5
22.5 =sensitive, 20
Hexane
Negative
control
Fluconazole (150mg/ml)
Gentamicin(0.4mg/ml)
540mg/ml
various Positive
control
270mg/ml
135mg/ml
67.5mg/ml
33.75mg/ml
16.88mg/ml
8.44mg/ml
Microorganisms Mean Zones of Inhibition at
Concentration of the Extract(mm)
0
0
0
24.5 0
and above =very
sensitive.
Table 5: Antimicrobial Activity assay of Methanol Seed Extracts of Moringa oleifera
Microorganisms Mean Zones of Inhibition at various Concentration Positive
of the Extract(mm)
control
Negativ
control
0
0
0
0
-10 =
0
0
0
8
19.5
0
0
0
0
10
0
0
0
12
20
0
0
0
9
15
moderately sensitive, 10- 20 =sensitive,
21.5
27.5
24
20 and
Methanol
Fluconazole
(150mg/ml)
Gentamicin(0.4mg/ml)
938.84mg/ml
469.42mg/ml
234.71mg/ml
117.36mg/ml
58.68mg/ml
29.34mg/ml
14.67mg/ml
E coli
0
P aeruginosa
0
K pnuemoniae
0
C albicans
0
Key: 0 = No Inhibition, 0
0
0
0
17.5
0
above =very
sensitive.
Table 6: Antimicrobial Activity assay of Hexane Seed Extracts of Moringa oleifera
E coli
0
P aeruginosa
0
K pnuemoniae
0
C albicans
0
Key: 0 = No Inhibition, 0
sensitive.
Percentage Activity
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-10 = moderately sensitive, 10-
0
0
0
0
0
0
0
20
20 = sensitive,
20
21
20
20 and
22
above =
Negative
Control
Hexane
Gentamicin(0.4mg/ml)
Fluconazole
(150mg/ml)
734mg/ml
367mg/ml
183.5mg/ml
91.75mg/ml
45.86mg/ml
22.94mg/ml
11.47mg/ml
Microorganisms Mean Zones of Inhibition at various Concentration Positive
of the Extract(mm)
control
0
0
0
0
very
Candida albicans had the highest percentage activity of 107.3% at 1040mg/ml with methanol
leaf extract when compared to the controls followed by Pseudomonas aeruginosa at 104.4%
(table 7). The percentage activity for Pseudomonas aeruginosa with hexane leaf and seed extract
was zero at their highest concentrations (540mg/ml and 734mg/ml respectively) (tables 8 & 10).
%Activity =
Microorganisms
Percentage Activity at various Concentration of the Extract
(%)
16.25mg/ml
32.5mg/ml
65mg/ml
130mg/ml
260mg/ml
520mg/ml
1040mg/ml
Table 7: Percentage Activity of Methanol Leaf Extracts of Moringa oleifera
E coli
0
0
0
0
0
0
92.73
P aeruginosa
0
0
0
0
0
58.33
104.4
K pnuemoniae
0
0
0
0
0
60.53
78.94
C albicans
0
0
0
0
0
73.17
107.3
Table 8: Percentage Activity of Hexane Leaf Extracts of Moringa oleifera
540mg/ml
270mg/ml
135mg/ml
67.5mg/ml
33.7mg/ml
16.88mg/ml
Percentage Activity at various Concentration of the Extract
(%)
8.44mg/ml
Microorganisms
Eschericia coli
Pseudomonas aeruginosa
Klebsiella pnuemoniae
Candida albicans
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
58.62
0
95.74
91.84
Microorganisms
Percentage Activity at various Concentration of the Extract
(%)
14.67mg/ml
29.34mg/ml
58.68mg/ml
117.36mg/ml
234.71mg/ml
469.42mg/ml
938.84mg/ml
Table 9: Percentage Activity of Methanol Seed Extracts of Moringa oleifera
Eschericia coli
Pseudomonas aeruginosa
Klebsiella pnuemoniae
Candida albicans
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
37.20
0
50
51.43
90.70
36.36
83.33
85.7
Table 10: Percentage Activity of Hexane Seed Extracts of Moringa oleifera
Microorganisms
Percentage Activity at various Concentration of the Extract
(%)
11.47mg/ml
22.94mg/ml
45.86mg/ml
91.75mg/ml
183.5mg/ml
367mg/ml
734mg/ml
Eschericia coli
Pseudomonas aeruginosa
Klebsiella pnuemoniae
Candida albicans
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
90.9
Minimum Inhibitory Concentration
The MIC value for the Methanolic extracts on E.coli was 1040mg/ml while for K. pneumonia
was 520mg/ml and 1040mg/ml.
Table 11: Minimum Inhibitory Concentration of Methanol Leaf Extracts of Moringa oleifera
E coli
+
+
+
+
+
+
P aeruginosa
+++
++
++
++
++
+
+
K pnuemoniae
+
+
+
+
+
C albicans
++
++
+
+
+
+
KEY: - = No growth; + = slight turbidity; ++ = moderate turbidity; +++ = very turbid
Minimum Bactericidal Concentration
Methanol
Negative
control
Fluconazole (150mg/ml)
Positive
control
Gentamicin(0.4mg/ml)
1040mg/ml
520mg/ml
260mg/ml
130mg/ml
65mg/ml
32.5mg/ml
16.25mg/ml
Microorganisms Turbidity at various Concentration of the Extract
+++
+++
+++
+++
Minimum bacteria concentration refers to the lowest concentration of antibiotic required to kill a
particular bacterium. The MBC for the methanol seed extract on E coli was 938.84m/ml, K
pneumonia was 58.68mg/ml and C albicans at 29.34mg/ml (table 12). The MBC for the
methanol and hexane leaf extracts and hexane seed extracts on all the organisms were at zero at
all concentrations.
Table 12: Minimum Bactericidal Concentration of Methanol Seed Extracts of Moringa oleifera
938.84mg/ml
0
136
0
0
Methanol
469.42mg/ml
12
N
0
0
Negative
control
Fluconazole (150mg/ml)
234.71mg/ml
36
N
0
0
Gentamicin(0.4mg/ml)
117.36mg/ml
45
N
0
0
29.34mg/ml
E coli
237
75
66
P aeruginosa
N
N
N
K pnuemoniae
10
20
0
C albicans
N
0
0
KEY: N = Numerous = ˃350 CFU/ml
14.67mg/ml
58.68mg/ml
Microorganisms Minimum Bactericidal Concentration at various Positive
Concentration of the Extract(CFU/ml)
control
0
N
N
N
N
0
0
0
Discussion
Moringa preparations have been cited in the scientific literature as having antibiotic and
antitrypanosomal activities (Fahey, 2005). The results from the phytochemical screening
revealed the presence of tannins, saponins, alkaloids and phenols. The presence of
pharmacologically useful substances such as tannins, flavonoids, alkaloids, saponins among
other pharmacologically active elements (Table 2) in the seed and leaf of Moringa oleifera as
revealed by phytochemistry confirms the diverse claims and application of parts of the plant in
treatment of ailments (Haristoy et al., 2005). Several plants which are rich in tannins have been
shown to possess antibacterial activities against a number of organisms (Doss et al., 2009).
Saponnins though are haemolytic on red blood cells, are harmless when taken orally and they
have beneficial properties of lowering cholesterol levels in the body (Amos- Tautua et al., 2011).
Alkaloids have been shown to possess both antibacterial (Erdemogli et al., 2009) and
antidiabetic (Constantino et al., 2003) properties and useful for such activities. Phenols and
phenolic compounds have been extensively used in disinfections and remain the standard with
which other bactericides are compared (Uwumarongie et al., 2007).
Thus, the antibacterial activities exhibited by the secondary metabolites: tannins,
saponins, alkaloids and phenols may be responsible for the antimicrobial activity of the extract.
The presence of secondary metabolites in plants have been reported to be responsible for their
antibacterial properties (Rojas et al., 2006; Nikitina et al., 2007; Udobi et al., 2008; Rafael et al.,
2009; Adeshina et al., 2010).
However, the present result reveals that the use of Moringa as an antimicrobial agent is
limited since only the methanol extracts of the seed and leaf exhibited major antimicrobial effect
on the microbes used in this study as compared to the hexane extracts (Tables 3-6). Generally,
the leaf extracts were more effective compared to the seed. This finding is corroborated by
Sankar, (2012). In his research, the methanol extract of leaves, flowers, barks, seeds and fruits of
Moringa oleifera at concentrations of 6mg/ml exhibited antibacterial activities against
Esherichia coli, Pseudomonas aeruginosa, Shigella dysenteriae and Shigella Flexneri. This
may be due to alkaloids and saponins being largely present in the methanol leaf extract.
Alkaloids are basically Nitrogen containing naturally occuring compounds commonly found to
have antimicrobial properties due to their ability to intercalate with the DNA of microrganisms
(Kasolo et al., 2010). Thus, it can be inferred that the Moringa oleifera leaf has more microbial
activity when compared to the seed.
Pseudomonas aeroginosa was found to be totally resistant to all the concentrations of the
hexane leaf extract (table 4). Generally, Gram negative bacteria are known to be resistant to the
action of most antibacterial agents including plant based extracts and these have been reported by
many researchers (Kambezi and Afolayan, 2008; El-Mahmood, 2009). Gram negative bacteria
have an outer phospholipids membrane with the structural lipopolysaccharide components,
which make their cell wall impermeable to anti-microbial agents. The methanol seed extract
displayed notable anti-bacterial activities against Pseudomonas aeruginosa (table 5). This is of
great importance because the infections caused by this bacterium are known to be difficult to
control. It is an opportunistic organism which has been reported to readily receive resistance
carrying plasmid from other bacteria species (Wiley et al., 2008).
The hexane seed extract was found to have no inhibitory effect on the microorganisms
except Candida albicans (Table 6). This may be due to the flavonoid being largely in the extract.
This was coroborated by Galeotti et al., 2008. Flavonoids are widely distributed in plants
fulfilling many functions. They have been shown to have antifungal activity in vitro (Galeotti et
al., 2008). The effect on zone of inhibition was generally low compared to the orthodox
antibiotics used in this study (Tables 6-9). The results of the antimicrobial sensitivity test was
found to be statistically significant (p˂0.05) (Appendix D)
The variations in the presence of the phytochemicals may be due to the choice of solvent used in
extraction. During extraction, solvents may have diffused into the plant material and solubilised
compounds with similar polarity (Ncube et al., 2008). Methanol is a polar solvent while hexane
is non polar. Methanol has been found to extract saponins which have antimicrobial activity
(Ncube et al., 2008). The ability of methanol extract to inhibit the growth of bacterial strains is
an indication of its antibacterial potential that might be employed in the management of bacterial
infections in the future. The age of the plant has been reported not to affect the phytochemicals
present in the plant (Bamishaiye et al., 2011).
The minimum inhibitory concentration showed E.coli to be bactericidal at 1040mg/ml and
bacteriostatic from 520mg -16.25mg/ml of the methanol leaf extract (table 11). The same goes
for Candida albicans.
Findings in this study suggests that methanol extracts of different parts of Moringa oleifera have
potential as antimicrobial compounds against pathogens and their ability to either block or inhibit
resistance mechanisms of bacteria and fungi could improve treatment and eradication of
microbial strains. Thus, these plant extracts could be used in the treatment of infectious diseases
caused by resistant bacteria. Therefore these results lay down a basis for investigation into the
search of compounds in M. oleifera responsible for antibacterial activity.
Since traditional medicine is mostly used as self care, Moringa oleifera, which is an herbal plant
that can be used in treating different ailments and malnutrition, it is therefore recommended that
it be cultivated by growing them in backyard gardens for ready availability.
References
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