Evaluation of the phytochemical composition and antimicrobial activity of lemongrass (Cymbopogon citratus) against some human pathogenic microorganisms

ABSTRACT

Antibiotic resistance has become a wide spread problem. The efficacy of two solvent extracts of Cymbopogon citratus against some test bacteria and fungi was evaluated. The test bacteria was; Staphylococcus aureus, and the test fungi was; Candida albicans. The phytochemical properties and the antimicrobial potency of Cymbopogon citratus (lemon grass) against selected microbial pathogens using chloroform and methanol as extracting solvents were assessed. The minimum inhibitory, bactericidal and fungicidal concentrations of the extracts were also screened. The result of phytochemical screening on C. citratus showed that three (3) active ingredients were present in both extract. These include; Flavonoid, Tannins, and Alkaloid as shown in table 1. The agar well diffusion method was used in determining the diameter of zone of inhibition at different concentrations (200mg/ml, 100mg/ml, 50mg/ml, 25mg/ml, and 12.5mg/ml) of the plant extract while the standard antibiotics chloramphenicol and fluconazole were used as positive control. The result revealed that the activity of the chloroform extracts of Cymbopogon citratus against Staphylococcus aureus had the highest diameter of zone of inhibition measuring 7.667mm while Candida albicans also showed higher zone of inhibition in the chloroform extract measuring 11.667mm. The Minimum Inhibitory Concentration (MIC) of the methanolic extract was 100mg/ml against both S. aureus and C. albicans while it was 100mg/ml against S. aureus and 25mg/ml against C. albicans of the chloroform extract. The minimum bactericidal concentration (MBC) of the methanolic extract was 100mg/ml while it was 100mg/ml for the chloroform extract. The minimum fungicidal concentration (MFC) of the methanolic extract was 100mg/ml while it was 25mg/ml for the chloroform extract. The effect of standard antibiotics (Chloramphenicol and Fluconazole) showed very high activity on the test organisms Staphylococcus aureus and Candida albicans. The ability of these extracts of C. citratus to inhibit the growth of bacteria and fungi is an indication of its broad spectrum antimicrobial potential which may be employed in the management of microbial infections.

TABLE OF CONTENTS

Declaration----------i

Certification-----------ii

Dedication-----------iii

Acknowledgement----------iv

Abstract-----------v

Table of contents---------vi

CHAPTER ONE

Introduction----------

1.1 Background of the study--------1

1.2 Statement of problem---------4

1.3 Justification----------5

1.4 Aim and objectives ---------6

1.5 Significance of the study---------7

1.6 Scope of the study ---------8

CHAPTER TWO

2.0 Literature review----------

2.1An overview on Lemon grass (Cymbopogon citratus) ----9

2.2 Background on Cymbopogon citratus-------10

2.3 Botanical description of Cymbopogon citratus------15

2.3.1 Taxonomical classification of Cymbopogon citratus-----16

2.4 Economic importance of Cymbopogon citratus------16

2.4.1 Medicinal uses of C. Citratus--------17

2.5 Fungi----------19

2.5.1 Candida----------20

2.5.2 Beneficial economic aspect of fungi-------24

2.6 Bacteria-----------25

2.6.1 Staphylococcus aureus---------25

2.6.2 Clinical manifestation of S. aureus-------27

2.6.3 Virulence factors and pathogenesis S. aureus infections----28

2.6.4 Epidemiology----------29

2.6.5 Economic importance of bacteria-------29

CHAPTER THREE

3.0 Materials and methods---------

3.1 Collection and processing of plant materials-----31

3.2 Preparation of plant extract--------31

3.3 Sources of test organism--------31

3.4 Phytochemical screening of chloroform and methanol extracts----32

3.4.1 Test for tannins----------32

3.4.2 Test for flavonoids---------32

3.4.3 Test for saponins---------32

3.4.4 Test for alkaloids---------32

3.5 Screening of extracts for antimicrobial activities-----33

3.5.1 Preparation of extract concentration-------33

3.6 Antifungal assay----------33

3.7 Antibacterial assay---------34

3.8 Determination of minimum inhibitory concentration (MIC) ----34

3.9 Determination of minimum bactericidal concentration (MBC) ----35

3.10 Determination of minimum fungicidal concentration (MFC) ----35

CHAPTER FOUR

4.0 Results----------36

CHAPTER FIVE

5.0 Discussion----------42

CHAPTER SIX

6.0 Conclusion----------45

6.1 Recommendations---------45

REFERENCES----------46

Appendix-----------53