The Effects Of Lemon Extracts On Some Pathogenic Organisms

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