ABSTRACT 

The antimicrobial activities of Costus afer and Dialium guineense extracts were tested against Staphylococcus aureus¸ Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli and Salmonella typhi using disc agar diffusion technique. The ethanol extracts from both plants inhibited the growth of all the organisms used in this study except Salmonella typhi. It was further shown that the sensitivity of the organisms to the extracts did not only vary from one organisms to another but also in concentrations used. The most sensitive organism to Costus afer and Dialium guineense extract was Staphylococcus aureus, while the least was Escherichia coli. The inhibition zone measured 21.3 ± 1.13mm, 11.0 ± 1.73mm, 14.3 ± 2.08 and 19.3 ± 2.08mm against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa, respectively at concentration of 100mg/ml. Thus while Staphylococcus aureus has the highest sensitivity, Escherichia coli has the least to Costus afer extract. The inhibition zones produced by Dialium guineense was 22.0 ± 3.16mm, 20.0 ± 4.36mm, 20.3 ± 2.08mm and 18.0 ± 2.00mm against Staphylococcus aureus, Escherichia  coli, Enterococcus faecalis and  Pseudomonas aeruginosa, respectively at 100mg/ml concentration. The Minimum Inhibitory Concentration (MIC) of extract of Costus afer was 12.5mg/ml, 25mg/ml, 12.5mg/ml and 12.5mg/ml against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa, respectively Dialium guineense produced Minimuim Inhibitory Concentration (MIC) values of 12.5mg/ml, 25mg/ml, 25mg/ml and 12.5mg/ml against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa, respectively. The result showed that the ethanol extracts of the plants produced appreciable inhibitory activity against the test organisms. These result support further research into the properties of the chemical substances producing these effects. 

TABLE OF CONTENTS

Cover page i

Certification ii

Dedication iii

Acknowledgements iv

Table of Contents v

List of Tables vii

List of Figures viii

List of Plates ix

Abstract x

CHAPTER ONE

1.0 Introduction 1

1.1 Aims and Objectives 4

CHAPTER TWO

2.0 Literature Review 5

2.1 Phytomedicine 5

2.1.1 Characteristics of Phytomedicine 6

2.1.2 The Demand and Phytomedicine 6

2.2 Therapeutic Benefits of Phytomedicine 7

2.3 Plants with Medicinal Properties 9

2.4 Costus afer 10

2.5 Dialium guineense 14

2.6 Major group of Antimicrobial Compounds from Plants 19

CHAPTER THREE

3.0. Material and Method 23

3.1 Collection and Identification of Plant Material 23

3.2 Processing and Extraction of Plant Material 23

3.3 Antimicrobial Testing 24

3.4 Determination of Minimum Inhibitory Concentration (MIC) of Plant Extracts  25

3.5 Phytochemical Analysis 26

3.5.1 Qualitative Evaluation 26

3.5.2 Quantitative Determination 27

CHAPTER FOUR

4.0       Result 31

CHAPTER FIVE

5.1 Discussion 39

5.2 Recommendation 40

5.3 Conclusion 40

References 41

Appendix 47 

LIST OF TABLES