ABSTRACT
Extracts of Capsicum annuum were studied for their antimicrobial potency against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Shigella spp and Candida albicans using the disc diffusion technique. Qualitative and quantitative phytochemical screening of the ethanol and aqueous extracts of the plant showed the presence of alkaloids, flavonoids, saponins, tannins, steroids, cyanogens and phenols with alkaloids being the dominant compound with a percentage composition of 0.52%. Both the aqueous and ethanolic extracts of Capsicum annuum showed antimicrobial activity against all the test organisms. In aqueous extract, Capsicum annuum showed good inhibitory activity mainly against Escherichia coli and Shigella spp with zone of inhibition of 19.67 mm ±1.16b and 14.33 mm ±1.52b respectively. The ethanol extract of the plant performed better against Staphylococcus aureus and Pseudomonas aeruginosa with zone of inhibition of 20.33 mm ± 3.06b and 14.33 mm± 0.58b respectively. Based on this finding, this extract may be an alternative to chemical preservatives and used as natural antimicrobial preservatives to reclaim the shelf-life of food.
TABLE
OF CONTENTS
Title
page i
Certification ii
Dedication iii
Acknowledgement iv
Table
of Contents v
List
of Tables viii
List
of Figures ix
Abstract x
CHAPTER ONE
Introduction 1
1.1 Background of the Study 1
1.2 Objectives
of the Study 4
CHAPTER TWO
Literature Review 5
2.1 Description of Capsicum annum (Chilli Pepper) 5
2.2 The
Origin of Chilli Pepper 5
2.3 Varieties
of Pepper 5
2.4 Intensity
of Pepper 7
2.5 Characteristics of Chilli
Pepper 7
2.6 Classification of Chilli
Pepper 8
2.7 Uses
of Pepper 8
2.7.1 Culinary Uses 8
2.7.2 Medicinal
Uses 9
2.7.3 Nutritional
Uses 9
2.7.4 Crop Defense Uses 10
CHAPTER THREE
Materials
and Methods 11
3.1 Collection of Materials 11
3.2 Preparation of Samples 11
3.3 Media Preparation 11
3.4 Production of Extract 12
3.5 Preliminary Phytochemical Screening 12
3.5.1 Qualitative Analysis of Phytochemicals 13
3.5.1.1
Test For Tannins 13
3.5.1.2
Test For Saponins 13
3.5.1.3
Test For Flavonoids 13
3.5.1.4
Test For Alkaloids 14
3.5.1.5
Test For Steroids 14
3.5.1.6
Test For Phenol 15
3.5.2
Quantitative
Determination of the Phytochemicals 15
3.5.2.1 Determination of Alkaloids 15
3.5.2.2
Determination of
Flavonoids 16
3.5.2.3
Determination of Tannins 16
3.5.2.4
Determination of Saponin 18
3.5.2.5
Determination of Phenols 19
3.5.2.6
Determination of
Cyanogenic Glycoside (HCN) 20
3.6 Antimicrobial Activity Test 21
3.7
Statistical Analysis 22
CHAPTER FOUR
Results
22
4.1 Qualitative Phytochemical Screening of Capsicum annuum 22
4.2 Quantitative Phytochemical Screening of Capsicum annuum 24
4.3 Antimicrobial Activity of Capsicum annuum 26
4.4 Relative Potencies of Capsicum annuum Extract 29
CHAPTER FIVE
Discussion
and Conclusion 31
5.1 Discussion 31
5.2 Conclusion 33
References
LIST OF TABLES
Table Title Page
4.1
Qualititative
Phytochemical Screening of Capsicum
annuum Extract 23
4.2 Phytochemical
Content of Capsicum annuum (%) 25
4.3 Antimicrobial
Activities of Capsicum annuum Extract
(Diameter
of Zone of Inhibition). 27
4.4
Relative Potency of Capsicum annum extracts antimicrobial
activity
Compared with standard antibiotics 30
LIST OF FIGURES
Figure
List Page
1:
Capsicum annum plant (chili pepper) 6
2:
Inhibition effect of Capsicum annum extract (Diameter of zone
of inhibition) 28
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND
OF THE STUDY
There
has been an increasing consumer demand for foods free or with low, if any,
added synthetic preservatives because synthetic preservatives could be toxic to
humans (Bedin, et al., 1999).
Concomitantly, consumers have also demanded for wholesome and safe food with
long shelf lives. These requirements are often contradictory and have put pressure
on the food industry for progressive removal of chemical preservatives and adoption
of natural alternatives to obtain its goals concerning safe food with long
shelf lives (Brull and Coote, 1999).
Spices
and herbs have been used for thousand of the centuries by many cultures to enhance
the flavour and aroma of food. Early culture also reorganized the values of
using spices and herbs in preventing foods and for their medical values. Spices
in the past decade confirm that the growth of both Gram-positive and
Gram-negative food-borne bacteria, yeasts and molds can be inhibited by garlic,
onion, cinnamon, clove, thyme, sage and other spices. Although, the primary
purpose of spices is to impart flavour and piquancy to food, the medicinal,
antimicrobial and antioxidant properties of spices have also been exploited
(Souza et al., 2005). The
antimicrobial activity of spices is documented and interest continues to the
present (Uraih, 2004).
The
growing concern about food safety has recently led to the development of
natural antimicrobials to control food-borne pathogens and spoilage bacteria.
Spices are one of the most commonly used natural antimicrobial agents in foods
and have been used traditionally for thousands of years by many cultures for
preserving foods and as food additives to enhance aroma and flavour (Souza et al., 2005).
Pepper plant
is a perennial woody vine growing up to 4 m in height on supporting trees,
pole, or trellises. The leaves are alternate, 5 - 10 centimeters long and 3 - 6
cm broad. The flowers are small, produced
on pendulous spikes 4 - 8 cm long at the leaf-nodes, the spikes lengthening up
to seven to 15 cm as the fruit matures (Azhar et al., 2005). The fruit
of the pepper is a drupe and when dried
it is a pepper corn. It is grown in
soil that is neither too dry nor susceptible to flooding, moist, well-drained
and rich in organic matter. The plant is propagated by first planting; it is first
planted in the nursery before transplanting the seedling to the farm.
The antimicrobial activities of plants and their extracts
against bacteria and fungi have been documented. Plant use in the control
management and cure of diseases is an age long practical Mudalige et al., (2011) reported that natural
plant products including medicinal plant extracts are being increasingly used
as agrochemicals, for the control of diseases. This was attributed to their
relative non-phytotoxicity, easy biodegradation and environmental friendliness.
Sofoewara, (1993) observed that the use of plant in traditional medications and
their effectiveness as antimicrobial agents, stems from their phytochemical
composition.
The use of Chilli pepper by humans is an age long
practice. Omolo et al. (2014)
reported the use of pepper to date back as far as 2500BC. The use of pepper has
become an integral part of diet culture of many people, all over the world
(Mortensen and Mortensen, 2009).
Botanically, pepper is a member of the plant family of
solanaceae, and has close relation to potato, tomato, eggplant, tobacco and
petunia (Omolo et al., 2014). It is
cultured in the tropics and sub-tropics that are warm and humid. According to
the authors, pepper is one of the oldest domesticated crops of the western world
and is also currently, the most widely grown spice in the world as it is a
major ingredient in most global cuisines.
Although, peppers are used as spice all over the world,
their flavour and pungent smell vary widely just as their content of the major
active ingredient, capsicum and capsaicinoid analogues vary (Dorantes et al., 2000). According to Seugill, et al. (2014) there is evidence that
Chilli peppers were incorporated into a number of medical preparations in
mesoamerican regions and the preparations were applied for a variety of
ailments including respiratory problems, bowel complaints, ear aches, and sores
etc. Again Brito – Argaez et al.
(2009) examined the omnipresent nature of pepper in the mesoamerican diets and
observed that, it is a spice. Peppers play substantial roles and occupy an
important position in their diet culture with very important nutritional
consequences. The authors also record the demonstration of high degree of
bioactivity by peppers which affects the nervous, cardiovascular and digestive
systems, while its chemical composition show high concentration of essential
nutrients, including Vitamin C.
In the present world, consumers demand for safe and high
quality foods, since there is wide spread information and enlightenment regarding
health data and information. The concern for food safety is on the risk due to
increasing occurrence of new food – borne disease out breaks caused by
pathogenic microorganisms. Also, pathogenic microorganisms are responsible for
many other non-food related diseases of humans and live stock and their control
with chemical agents has witnessed high level of uneasiness (Cichewicz et al., 1996).
Outside epidermic cases, food-borne pathogens represent a
major public health concern (FDA 2013). Again, not much work has been
documented on photochemistry and health benefit of local pepper plant, whereas
much has been done in the western world on the antimicrobial properties and
activities of chilli-pepper plant (mainly on the fruits). It is a reported knowledge
that the activity of plant extract against pathogens, stems from their
phytochemical composition which in itself
is affected by agronomic factors, since plant synthesize and accumulate
there substances with what they are able to absorb from their natural soil
environment. Documented records of extract of chilli – peppers and their
general and specific antimicrobial activities are many Kalia et al., (2012). Report also show that
chilli peppers are receiving a lot of research attention elsewhere, and the
capsicum genus is reported to be a good source of antimicrobial and antifungal
compounds (Tajkarimi et al., 2010).
Concern has been expressed about the rising prevalence of
pathogenic microorganisms which are resistance to the newer modern antibiotics
that have been produced in the last three decade (Nascimento et al., 2000).
Coincidentally, the last decades has also witnessed increasing intensity
studies on extract and biological active compound isolated from plant species
used for natural therapies or herbal medicine (Nascimento et al., 2000; Rios and Recio, 2005). For over a thousand year,
natural plants have been seen as a valuable source of medicinal agent with
proven potentials in the treatment of infectious diseases and with lesser side
effects compared to synthetic drug agent (lwu et al., 1999). However the
problem pose by high costs, adulteration and increasing side effect of
synthetic drug coupled with their inadequacy to diseases treatment especially
in the developing countries cannot be ignored (Shariff, 2001).
1.2 OBJECTIVES OF THE STUDY
i.
To
determine the antimicrobial activity of chilli pepper plant leaves against
pathogenetic microorganisms.
ii.
To
determine the phytochemical constituents of chilli pepper leaf.
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