ABSTRACT
Euporbia hirta, Breynia nivosa, Euphorbia heterophylla and Manihot esculenta powdered plant material were extracted using two solvents, ethanol and water. The ethanol extracts provided the higher yield and also more antimicrobial effectiveness than aqueous extracts. Phytochemical screening of the crude extracts revealed the presence of alkaloids, saponin, tannins, flavonoids, phenols and hydrogen cyanide (HCN). The plant extracts had a high percentage of HCN ranging from 13.48±0.03 to 39.15±0.04%. The presence of these bioactive constituents have been linked to the antimicrobial activity of the plant materials. The disc diffusion method was used to determine the antimicrobial activity against Pseudomonas aeruginosa, Enterobacter aerogenes, Salmonella pullorum and Proteus vulgaris.Minimum inhibitory concentrations was analysed using agar well diffusion method with values ranging from 50 to 200mg/ml. The growth of all the bacteria were inhibited through to varying degrees, thus justifying the use of the herbs in traditional medicine in treating enteric infections. P. vulgaris and P. aeruginosa were more susceptible with diameters ranging from 19mm and 16.33mm respectively. The antimicrobial activity of the plant materials is enhanced under acidic conditions and at elevated temperatures. The herbs E. hirta, B. nivosa, E. heterophylla and M. esculenta can be used as sources of oral drugs to fight infections caused by susceptible bacteria.
TABLE
OF CONTENTS
Cover
page
Title
page i
Declaration
ii
Certification
iii
Dedication
iv
Acknowledgement
v
Table
of content vi
List
of tables viii
List
of plates ix
Abstract
x
CHAPTER ONE
INTRODUCTION 1
1.1
Aim and Objectives 2
1.2
Justification 3
1.3
Botany of the plants 3
1.3.1 Botany
of Manihot esculenta Crantz (Cassava) 3
1.3.2 Botany
of Breynia nivosa W. Bull(Small-Snow
bush) 4
1.3.3 Botany
of Euphorbia hirta Linn (Asthma
plant) 5
1.3.4 Botany
of Euphorbia heterophylla Linn (Purge
weed) 6
CHAPTER
TWO
2.1 Literature review 7
2.1.1 Phytochemical screening of plants 7
CHAPTER
THREE
3.0 Materials and methods 10
3.1 Collection of plant materials and
identification 10
3.1.1 Preparation of the samples for analysis 10
3.2 Phytochemical analysis 11
3.2.1 Qualitative analysis on leaf extract 11
3.1.1. Test for the presence of tannins 11
3.2.1.2 Test for
the presence of saponins 11
3.2.1.3 Test for
flavonoids 12
3.2.1.4 Test for
the presence of Alkaloids 12
3.2.1.5Test for
the presence of phenols 13
3.3 Quantitative analysis of phytochemicals 13
3.3.1 Determination of tannins 13
3.3.2 Determination of alkaloids 14
3.3.3 Determination of phenols 15
3.3.4 Determination of flavonoids 16
3.3.5 Determination of saponin 17
3.3.6 Determination of hydrogen cyanide (HCN) 18
3.4 Determination of antimicrobial activity 19
3.4.1 Production of plant extracts 19
3.4.2 Source of test organisms 20
3.4.4 Determination of minimum inhibitory
concentration 21
3.4.5 Statistical Analysis 22
CHAPTER
FOUR
4.0 Results 26
4.1 Phytochemical properties 26
4.1.1 Quantitative analysis 26
4.1.2 Qualitative analysis 27
4.1.3 Antimicrobial activity 29
4.1.4 Minimum inhibition concentration (MIC) 30
CHAPTER FIVE
5.0 Discussion and conclusion 37
5.1 Discussion 38
5.2 Conclusion 43
References
LIST OF TABLES
Table
1: Qualitative analysis of
phytochemicals present in
E.
hirta, B. nivosa, E. heterophylla and M. esculenta. 27
Table
2: Quantitative analysis of
phytochemicals present in E. hirta,
B.
nivosa, E. heterophylla and
M. esculenta. 28
Table3:
Antimicrobial activity of the
aqueous and ethanolic
extracts of Euphorbia
hirta, Breynia nivosa, 30
Euphorbia
heterophylla and Manihot esculenta against the
test organisms (P.aeruginosa, E.aerogenes, S.pullorum
and P.vulgaris)
Table
4: The minimum inhibitory
concentrations (MIC – mm) of
the plant extracts
against the test organism (P. aeruginosa) 31
Table
5: The minimum inhibitory
concentrations (MIC – mm) of the
plant extract against the test organism (E. aeruginese) 32
Table
6: The minimum inhibitory
concentrations (MIC – mm) of the
plant extract
against the test organism (S.pullorum) 33
Table
7: The minimum inhibitory
concentration (MIC- mm) of the
plant extracts
against P. vulgaris 34
LIST OF PLATES
Plate 1: The leaves of Euphorbia hirta 23
Plate 2: The leaves of Breynia nivosa 23
Plate 3: The leaves of Euphorbia heterophylla 24
Plate 4: The leaves of Manihot esculenta 24
Plate 5: Solidified Muller Hinton agar in
sterile petri dishes 25
Plate 6: Zone inhibition for aqueous and
ethanolic leaf extract of
Euphorbia
heterophylla on Salmonella pullorum 35
Plate 7 Zone of inhibition for aqueous and
ethanolic leaf extract of
Euphorbia
hirta on Salmonella
pullorum 36
CHAPTER ONE
1.0 INTRODUCTION
Antimicrobial agents are substances that
interfere with the growth and metabolism of microbes. In common usage the term
denotes inhibition of growth and with reference to specific groups of organisms;
such terms as antibacterial, antifungal, antiviral and antiprotozoal are
frequently employed. Antimicrobial agents may either kill microorganism or
inhibit their growth. Antimicrobial agents are particularly useful in
situations which the normal host defenses cannot be relied on to remove or
destroy pathogen (Nester et al.,
2004).
Plants have provided a source of
inspiration for novel drug compounds, as plant derived health and wellbeing.
Plant extract have been used for a wide variety of purposes for many thousands
of years (Jonnes, 1996).
Medicinal plants have continued to attract
attention in the global search for effective antimicrobial agents that can
combat resistant pathogens that have been rendering many conventional drug
obsolete in the treatment of infections (Cox, 1990).
Many important drugs used in medicine
today are directly or indirectly derived from plants. A number of plants have
been used in traditional medicine for many years due to their antimicrobial
properties (Sofowora, 1993). Specifically, the medicinal value of these plants
lies in some chemical substance that produce a definite physiological action on
the human or animal body (Edeoga et al.,2005).
Since ancient times, plants with therapeutic properties have secured an
important place in the healing practices and treatment of diseases (Mohammad,
2011).
Medicinal plants are of great importance
to the health of individuals and communities. Modern scientists have made
phenomenal step in developing this heritage handed over by our forefathers
(Sofowara, 1986).
In Nigeria, application of medicinal
plants especially in traditional medicine is currently well acknowledged and
established as a visible profession (Kafaru, 1994).
Extraction of bioactive compounds from
medicinal plants permits the demonstrations of their studies leading to
synthesis of a more portend drugs with reduced toxicity (Ebana et al., 1991).
Presently in the developing countries,
synthetic drugs are inadequate for the treatment of diseases but are also often
with adulterations and side effects (Shariff, 2001). Therefore, there is need
to search for suitable plants of medicinal value to be effective in the
treatment of diseases, which must be harmless to human tissues. Medicinal
plants still remains the primary source of supply of many important drugs used
in orthodox medicine today. Investigation into the chemical and biological
activities of plants in the past years have yielded compounds for the
development of modern synthetic organic compounds as a major route for the
discovery of novel and more effective therapeutic agents. The African continent
is one which is endowed with one of the richest biodiversity in the world with
abundance of many plants used as herbs, foods and for therapeutic purposes.
Great need arises for the evaluation of the pharmacological properties and
detailed screening of bioactive substances for chemotherapeutic purposes.
Furthermore, investigation into the antimicrobial activities of these plants
will show that plants are potential source of synthetic drugs (Clark, 1996;
Kubmarawa et al., 2009).
The active principles for many drugs found
in plants are secondary metabolites (Ghani, 1990). Phytochemicals are chemical
compounds that occur naturally in plants. Medicinal properties of the plants
are generally dependent on the presence of certain phytochemicals such as
alkaloids, tannins, saponins, flavonoids, reducing sugar and anthraquinone with
bioactive bases thought to be responsible for antimicrobial property (Ebana et al., 1993).
Alkaloids are a group of mildly alkaline
compound because it is astringent. Saponins occurs widely in varieties of
plant, they are used as cleaning agent. Some of the saponins are useful as raw
materials for synthesis of steroid hormones. In recent years, secondary
metabolites previously with unknown pharmacological activities have been
extensively investigated as a source of medicinal agents (Krishnaraju et al., 2005).
Phytochemicals with adequate antimicrobial
efficacy will be used for the treatment of the bacterial infections (Balandrin et al., 1985). Natural products are
therefore gaining attention as an alternative for antimicrobial agents (Helal et al., 2015).
1.1.2 AIMS AND OBJECTIVE OF THE RESEARCH
(i) To determine the phytochemicals of the
leaf extracts of Terminalia catappa, Gongronema
latifolium, Piper guineenses and
Psidium guajava.
(ii) To determine the plant with the best
antimicrobial properties
1.1.3 JUSTIFICATION OF THE STUDY
Many important drugs used in medicine
today are directly or indirectly derived from plants. A number of plants have
been used in traditional medicine for many years due to their antimicrobial
properties. The use of medicinal plant reduces side effect.
The result of this study will demonstrate
the antimicrobial properties of the plant extracts that will kill or inhibit
the growth of microorganisms and in the concentration in which the plant
extracts will be effective in treating microbial infections. The minimum
inhibitory concentration (MIC) will help in resolving the problem of dosage.
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