ABSTRACT

Antifungal activities of rosemary (Rosmarinus officinalis), Eucalyptus (Eucalyptus globulus) and Lemon (Citrus limon) essential oils evaluated, suppressed the mycelial growth of postharvest pathogenic fungus Colletotrichum. The experiment carried out using the Agar well diffusion method in 75% and 100% concentration of the essential oils on SDA culture at 250C and growth measured after 3days showed that the essential oils did not have much antifungal activities on the test fungus. The Agar incorporation method showed that the three (3) essential oils had effect on the fungus. The antifungal activity was replicated three times with Eucalyptus essential oil having the highest inhibition of 100% on the mycelial growth of Colletotrichum followed by rosemary essential oil which had 95.24% inhibition on the growth of the fungus Colletotrichum, Lemon essential oil had the least antifungal activity of 76.19%. The GC-MS analysis of the essential oils revealed the presence of Eucalyptol, Oleic acid, Bicyclo[2.2.1] heptan-2-one,1, 7,7-trimethylethyl, 1R-alpha-pinene, D-Limonene which could be responsible for the antifungal activities of the different essential oils. These essential oils could be used as possible biofungicides as an alternative to synthetic fungicides against pathogenic fungi on tomato fruits.

TABLE OF CONTENTS

Certification i

Dedication ii

Acknowledgement iii

Table of Contents iv

List of Tables viii

List of Appendix ix

Abstract                                                                                                      x 

CHAPTER ONE

INTRODUCTION

1.1 Introduction 1

1.2 Aims and objectives 3

CHAPTER TWO

LITERATURE REVIEW

2.1    Essential oils 4

2.1.1 Extraction of essential oils  4

2.1.2   Therapeutic benefits of essential oils 6

2.1.3   Absorption through the skin 7

2.1.4    Inhalation 7

2.1.5    Ingestion 7

2.1.6    Mechanism of the biological activities of essential oils 8

2.1.7    Antibacterial and antifungal action 8

2.1.8    Antiviral activity 9

2.2       Methods of extraction of essential oils 9

2.2.1    Maceration 10

2.2.2    Cold pressing 10

2.2.3    Solvent extraction 10

2.2.4     Enfleurage 11

2.2.5     Hydrodistillation 11

2.2.6     CO2 and supercritical CO2 extraction 11

2.2.7      Steam distillation 12

2.3         Spoilage of tomato 13

2.4         Colletotrichum species 14

2.4.1      General characteristics of Colletotrichum 14

2.5         Description of plant materials and fruit 15

2.5.1      Rosmarinus officinalis          15

2.5.1.1   Description of the oil 16

2.5.1.2    Experimental pharmacology       16

2.5.2       Citrus limon 17

2.5.2.1    Lemon essential oil 17

2.5.3       Description of Eucalyptus globulus 18

CHAPTER THREE

MATERIALS AND METHODS

3.1         The study area 20

3.2         Sample collection and identification 20

3.3         Gas chromatography- Mass Spectometry (GC-MS) 20

3.4         Identification of isolate 20

3.5         Assays for antimicrobial activity 21

3.5.1      Agar well diffusion assay 21

3.5.2      Agar incorporation assay 22

3.6        Statistical analysis 22

CHAPTER FOUR

RESULTS                                  23

CHAPTER FIVE

DISCUSSION AND CONCLUSION

5.1    Discussion 33

5.2    Conclusion 35

References                                                                                                                36

Appendix

LIST OF TABLES

Table                 Title                  Page

1 Colonial features of isolate        24

2 Microscopic observation of isolate           25

3 Agar well diffusion method        26

4 Agar incorporation method        27

5 Comparison of the mean difference of the test groups and the control group      28

6          Characterization of Rosmarinus officinalis (ROSEMARY) essential oil        29

7          Characterization of Eucalyptus globulus (EUCALYPTUS) essential oil        30

 8         Characterization of Citrus limon (LEMON) essential oil             32

LIST OF APPENDIX

Appendix                Title

1                Chromatogram-Rosmarinus officinalis

2                Chromatogram- Eucalyptus globulus

3                Chromatogram- Citrus limon

4                Zone of inhibition of Citrus limon essential oil

5                Zone of inhibition of Eucalyptus globulus essential oil   

6                Zone of inhibition of Rosmarinus officinalis essential oil      

7                Colonies of Colletotrichum on incorporation of Rosmarinus officinalis essential oil           

8                Colonies of Colletotrichum on incorporation of Citrus limon essential oil    

9                Colonies of Colletotrichum on incorporation of Eucalyptus globulus essential oil 

10              Colonies of Colletotrichum on incorporation of Eucalyptus globulus essential oil