ABSTRACT

The leaves of Acanthus montanus and Alstonia congensis were powdered, screened for phytochemicals and their antibacterial activities. Antibacterial activities of the crude extracts against ATCC strains of Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 7080), and Salmonella typhi (ATCC 7080) were investigated using agar diffusion and broth dilution methods. Gentamicin, a standard antibiotic was used as control. The mean diameter zone of inhibition produced by ethanol extract of Alstonia congensis  and Acanthus montanus on the test organisms at various concentrations were as follows: S. aureus (15mm at 100mg/ml, 10mm at 50mg/ml and 9mm at 25mg/ml for A. montanus; 13mm at 100mg/ml, 11.5mm at 50mg/ml and 8mm at 25mg/ml for A. congensis). E. coli (12.5mm at 100mg/ml, 11mm at 50mg/ml and 9.5mm at 25mg/ml for A. montanus with no effect by extract of A.congensis). E. faecalis (11mm at 100mg/ml and 10mm at 50mg/ml for A. montanus; 10mm at 100mg/ml and 9mm at 50mg/ml for A. congensis). The extracts at various concentrations had no effect on Salmonella typhi. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of the ethanol extract of Acanthus montanus were as follows; 12.5mg/ml and 25mg/ml for S. aureus, 25mg/ml and 50mg/ml for E. coli and 25mg/ml and 50mg/ml for Enterococcus faecalis. The MIC and MBC values of the ethanol extract of Alstonia congensis were as follows; 6.25mg/ml and 12.5mg/ml for S. aureus, 25mg/ml and 50mg/ml for Enterococcus faecalis. The phytochemical screening of the plants Acanthus montanus and Alstonia congensis was also carried out and it was found that the plants contained flavonoids, saponins, tannin and terpenoids. In conclusion, the crude extracts of Alstonia congensis  and Acanthus montanus  possess strong antibacterial activities and further investigation should be carried out to isolate pure compounds and determine the mechanisms of action of the plants. 

TABLE OF CONTENTS

Title page i

Certification page ii

Dedication iii

Acknowledgements iv

Table of contents v

List of tables vii

List of figures viii

Abstract ix

CHAPTER ONE

1.0 INTRODUCTION 1

1.1 Aims and Objectives 3

CHAPTER TWO

2.0 LITERATURE REVIEW 4

2.1 Importance of medicinal plant in Traditional Medical practice 4

2.2 The plant Alstonia congensis 5

2.3 Documented Species Distribution 6

2.4 Systematic Position of A. congensis 7

2.5 Chemical Composition (Phytochemistry) of A. congensis 7

2.6 Ethnobotanical Uses of A. congensis 10

2.7 Antibacterial properties of A. congensis 11

2.8 The Plant Acanthus montanus 13

2.9 Origin and geographical distribution of A. montanus 14

2.10 Scientific classification of A. montanus 14

2.10.1 Common names for Acanthus montanus 14

2.10.2 Vernacular names for Acanthus montanus 15

2.10.3 Propagation and management of Acanthus montanus 15

2.10.4 Ethnomedical Uses of Acanthus montanus 16

2.10.5 Biological Activities of the Plant Acanthus montanus 17

2.10.6 Antimicrobial, anti-inflammatory and immunological activity 19

2.10.7 Anti-abortifacient activity 20 

CHAPTER THREE

3.0       MATERIALS AND METHODS 22

3.1 Plant samples 22

3.2 Preparation of samples for analysis 22

3.3 Preparation of Stock Solution of Plant Extract 22

3.4 Reactivation of Test Microorganism 22

3.5 Antimicrobial Testing 23

3.6 Determination of MIC of Plant Extracts 24

CHAPTER FOUR

4.0       RESULTS 25

CHAPTER FIVE

5.0 DISCUSSION, CONCLUSION AND RECOMMENDATION 29

5.1 Discussion 29

5.2 Conclusion 30

5.3 Recommendation 30

REFERENCES 31