ABSTRACT

Plants have formed the basis of traditional systems of medicine that have been in existence since time immemorial and continued to provide mankind with new remedies. The antimicrobial activity of different parts (stem, leaf and root) of lemon extracts on some pathogens was investigated with different solvents (Methanol and Ethanol) against test organisms (Esherichia coli, Staphylococcus aureuas) using agar well diffusion method. The different extracts were prepared at different concentration (50mg/ml, 100 mg/ml, 150mg/ml and 200mg/ml). Amongst the different parts (stem, leaf and root) of lemon extracts studied, the methanoic extracts have more significant inhibitory effect than the ethanolic extracts. The methanoic extracts of leaf plant part recorded pronounced antibacterial activity against the test pathogens (Staphylococcus aureus) with zones of inhibition varying between 18 mm against Staphylococcus aureus isolate to 13 mm in Escherichia coli at a concentration of 200mg/ml. At the concentration of 200mg/ml, the leaf methanol extract showed the best result with the zone of inhibition of 18mm whereas the stem methanol extract showed the lowest effect with a zone of inhibition of 8mm. The antimicrobial potential of the different parts (stem, leaf and root) of lemon extracts must have resulted due to the presence of bioactive secondary metabolites such as flavonoids, tannins and phenols which have been shown to possess antimicrobial properties. Methanoic extracts and ethanolic extracts of different parts (stem, leaf and root) of lemon have broad-spectrum antimicrobial activity; hence can serve as natural therapeutic agent against some enteric pathogens

TABLE OF CONTENTS

Title Page     i

Certification iii

Dedication iv

Acknowledgements v

Table of Contents vi

List of Tables vii

Abstract ix

CHAPTER ONE

1.0 Introduction 1

1.2 Aim and Objectives 3

CHAPTER TWO

2.0 Literature Review 4

2.1 Lemon 4

2.2 History 6

2.3 Phytomedicine 7

2.4 Risk of Phytomedicine 7

2.5 Phytochemicals 8

2.6 Classes of Phytochemical 8

2.6.1 Alkaloids 9

2.6.2 Glycosides 9

2.6.3 Flavonoids 10

2.6.4 Phenolics 10

2.6.5 Saponins 11

2.6.6 Tannins 11

2.7 Mechanism of Action of Phytochemical 12

2.8 Test Organisms 12

2.8.1 Escherichia coli 12

2.8.2 Staphylococcus aureus 14

CHAPTER THREE

3.0 Materials and Methods 15

3.1 Plant Materials 15

3.2 Sterilization Methods 15

3.3 Processing of the Plant 15

3.4 Preparation of Crude Extracts 15

3.5 Phytochemical Screening of Extract 16

3.5.1 Test for Glycosides 16

3.5.2 Test for Steroids 16

3.5.3 Test for Tannins 16

3.5.4 Test for Alkaloids 17

3.5.5 Test for Flavonoids 17

3.5.6 Test for Saponins 17

3.6 Preparation of Concentration of Plant Extract 17

3.7 Test Organisms 18

3.8 Preparation of Bacterial Inoculum 18

3.9 Determination Of Minimum Inhibitory Concentration (MIC) 18

3.10 Minimum Bactericidal Concentration (MBC) 18

3.11 Antibacterial Susceptibility Testing of the Extracts with Test the 19

Organisms

CHAPTER FOUR

4.0 Result 20

CHAPTER FIVE

5.0 Discussion, Conclusion and Recommendation 25

5.1 Discussion 25

5.2 Conclusion 27

5.3 Recommendation 27