ANTIBACTERIAL ACTIVITY OF LEAF EXTRACTS OF Colocasia esculenta AND Caladium bicolor ON CLINICAL ISOLATES

ABSTRACT

Two extracts from two Nigeria medicinal plants, Colocasia esculenta and Caladium bicolor were screened for antibacterial activities using disc diffusion and micro dilution broth assays. Methanol extracts of each of the plants were tested against four microorganisms consisting of two Gram positive bacteria (Staphylococcus aureus and Streptococcus faecalis) and two Gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The antibacterial activity was measured by the diameter zone of inhibition and minimum inhibitory concentration (MIC). The extracts exhibited moderate broad spectrum antibacterial activities against the microorganisms. The diameter of zone of inhibition ranges from 10mm-15mm at 2000mg/ml of crude extract per disc. The MIC values were between 125mg/ml-100mg/ml. The activities of some of the crude extracts were comparable to the reference antibiotics (Gentamicin) at standard concentration per disc. These findings have shown the potentials of these extracts for antibacterial activities against clinical isolates.

TABLE OF CONTENTS

Title Page ﾿ i

Certification ﾿ ii ﾿            

Dedication ﾿ iii

Acknowledgements ﾿ iv ﾿

Table of Contents ﾿ v ﾿

List of Tables ﾿ vii ﾿

List of Figure ﾿ viii

Abstract ﾿ ix ﾿   

CHAPTER ONE ﾿ 1

1.1 ﾿ Introduction ﾿ 1 ﾿

1.2 ﾿ Aims and objectives ﾿ 2

CHAPTER TWO ﾿ 3

2.0 ﾿      Literature review ﾿ 3

2.1 ﾿ Examples of plants used as medicine ﾿ 4 ﾿

2.2 ﾿ Active chemical constituents of medicinal action of plant ﾿ 6

2.3 ﾿ Clinical isolates ﾿ 10

2.4 ﾿ Description of the plants ﾿ 16

2.4.1 ﾿ Colocasia esculenta ﾿ 16 ﾿

2.4.2 ﾿ Caladium bicolor ﾿ 16

CHAPTER THREE ﾿ 18 ﾿

MATERIALS AND METHODS ﾿ 18

3.1 ﾿ Collection and identification of plant materials ﾿ 18 ﾿

3.2 ﾿ Preparation of  plant extracts ﾿ 18 ﾿

2.2.1 ﾿ Methanol extract ﾿ 18

3.3 ﾿ Test organism ﾿ 20 ﾿

3.4 ﾿ Preparation of plant extract concentration ﾿ 20

3.4.1 ﾿ Disc diffusion assay ﾿ 20 ﾿

3.5 ﾿ Control experiment using Gentamycin and Dimethyl Sulphuroxide ﾿ 21 ﾿

3.6 ﾿ Preparation of culture media and antibacterial activity ﾿ 21 ﾿

3.7 ﾿ Determination of Minimum inhibitory concentration ﾿ 22

CHAPTER FOUR ﾿ 23 ﾿

RESULTS ﾿ 23 ﾿

4.1 ﾿ Percentage yield of plant extracts ﾿ 23

4.2 ﾿ Antibacterial activity of plant extracts ﾿ 23

4.3 ﾿ Minimum inhibitory concentration test results of the plant extracts ﾿ 24

CHAPTER FIVE ﾿ 27 ﾿

DISCUSSION AND CONCLUSION ﾿ 27 ﾿

5.1 ﾿ Discussion ﾿ 28

5.2 ﾿ Conclusion ﾿ 29

References ﾿