ANTIMICROBIAL PROPERTIES OF SELECTED ASIAN HERBS

107 Pages·2008·0.92 MB·English

ANTIMICROBIAL PROPERTIES OF SELECTED ASIAN HERBS

By

THABILE PRECIOUS NKAMBULE

A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2008
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© 2008 Thabile Precious Nkambule

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To my Family and Friends

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ACKNOWLEDGMENTS
I would like to express my special appreciation to my advisor Dr. Amarat H. Simonne (my
supervisory committee chair) and Dr. Charles Sims, Dr. Samuel R. Farrah, and Dr. Maurice R.
Marshall, Jr., for serving on my committee. I would also like to thank Rob M. Pelick, Kimberly
Evans, and Wei-Yea Hsu for their assistance and support. I would also like to thank the faculty
and staff of Food Science and Human Nutrition department, University of Florida. I would like
the express much appreciation to my family for their love, encouragement, and support.

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TABLE OF CONTENTS

page
ACKNOWLEDGMENTS...............................................................................................................4 
LIST OF FIGURES.......................................................................................................................10 
LIST OF ABBREVIATIONS........................................................................................................11 
ABSTRACT...................................................................................................................................12
CHAPTER
1 INTRODUCTION..................................................................................................................15 
2 LITERATURE REVIEW.......................................................................................................19 
Most Common Asian Herbs and Spices.................................................................................20 
Lemongrass......................................................................................................................21 
Turmeric..........................................................................................................................22 
Antimicrobial Activities of Lemongrass (Cymbopogon citratus)............................23 
Antimicrobial Activities of Turmeric (Curcuma longa)..........................................30 
Drying Methods......................................................................................................................33 
Oven-Drying....................................................................................................................34 
Freeze-Drying..................................................................................................................35 
Extraction Solvents.................................................................................................................39 
Dimethyl Sulfoxide (C H OS)........................................................................................40 
2 6
Water (H O).....................................................................................................................40 
2
Ethanol (C H O)..............................................................................................................41 
2 6
Hexane (C H )................................................................................................................41 
6 14
Acetone (C H O).............................................................................................................41 
3 6
Effect of Extraction Solvents on the Antimicrobial Properties of Herbs........................41 
Evaporation Techniques.........................................................................................................43 
Rotary Rotavapor....................................................................................................................43 
3 MATERIALS AND METHODS...........................................................................................51 
Bacterial Strains and Cultivation............................................................................................51 
Plant Materials........................................................................................................................51 
Preparation of Plant Material..................................................................................................52 
Preparation of Plant Extracts..................................................................................................52 
Antimicrobial Assay...............................................................................................................54 
Minimum Inhibitory Concentration (MIC) Determination....................................................55 
Minimum Bactericidal Concentration (MBC) Determination................................................56 
Experimental Design and Statistical Analysis........................................................................56 
4 RESULTS AND DISCUSSION.............................................................................................60 
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Antimicrobial Activity of Lemongrass...................................................................................60 
Inhibitory Zone of Lemongrass Extracts.........................................................................60 
Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal
Concentration (MBC) of Lemongrass Stem Extracts..................................................64 
Antimicrobial Activity of Turmeric Extracts.........................................................................66 
Inhibitory Zone of Turmeric (Fresh Rhizomes and Dried Powder) Extracts..................66 
Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal
Concentration (MBC) of Turmeric (Fresh Rhizomes and Dried Powder) Extracts....68 
5 SUMMARY AND CONCLUSSION.....................................................................................81
APPENDIX
A ANALYSIS OF VARIANCE (ANOVA) TABLES: ANTIMICROBIAL ACTIVITY
OF LEMONGRASS STEMS.................................................................................................83 
B ANALYSIS OF VARIANCE (ANOVA) TABLES: ANTIMICROBIAL ACTIVITY
OF TURMERIC (FRESH RHIZOMES)................................................................................91 
C ANALYSIS OF VARIANCE (ANOVA) TABLES: ANTIMICROBIAL ACTIVITY
OF TURMERIC (DRIED POWDER)....................................................................................96 
LIST OF REFERENCES.............................................................................................................100 
BIOGRAPHICAL SKETCH.......................................................................................................107 

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LIST OF TABLES

Table page

2-1 Reported and estimated cases, number of outbreaks and deaths caused by known
foodborne bacterial pathogens from 1983 to 1997............................................................45 
2-2 Most common pathogens associated with foodborne illness outbreaks............................46 
2-3 Common Asian herbs used for cooking.............................................................................48 
2-4 Properties of different solvents..........................................................................................49 
4-1 Inhibitory zone (mm) of lemongrass stems extracts (solvent extracts) on bacterial
pathogens...........................................................................................................................71 
4-2 Inhibitory zone (mm) of turmeric (fresh rhizome) extracts (solvent extracts) on
bacterial pathogens.............................................................................................................72 
4-3 Inhibitory zone (mm) of turmeric (dried powder) extracts (solvent extracts) on
bacterial pathogens.............................................................................................................73 
4-4 Overall comparison of solvents, drying methods, and harvest-time for lemongrass
stem....................................................................................................................................74 
4-5 Sensitivity of each Staphylococcus aureus strain to lemongrass stem..............................75 
4-6 Antimicrobial activities of fresh rhizome turmeric extracts..............................................76 
4-7 Sensitivity of each Staphylococcus aureus strain to fresh rhizome turmeric extracts.......77 
4-8 Antimicrobial activities of dried powder turmeric extracts...............................................78 
4-9 Sensitivity of each Staphylococcus aureus strain to dried powder turmeric extracts........79 
4-10 Comparison of lemongrass stem and turmeric (fresh rhizomes) extracts..........................80 
4-11 Comparison of fresh rhizomes and dried powder turmeric extracts..................................80 
A-1 Inhibitory zone of lemongrass stems.................................................................................83 
A-2 Minimum Inhibitory Concentration (MIC) of lemongrass stem........................................83 
A-3 Minimum Bactericidal Concentration (MBC) of lemongrass stem...................................84 
A-4 Inhibitory zone of lemongrass stems against Staphylococcus aureus ATCC 12600-U....85 
A-5 Minimum Inhibitory Concentration (MIC) of lemongrass stem against
Staphylococcus aureus ATCC 12600-U............................................................................86 
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A-6 Minimum Bactericidal Concentration (MBC) of lemongrass stem against
Staphylococcus aureus ATCC 12600-U............................................................................86 
A-7 Inhibitory zone of lemongrass stems against Staphylococcus aureus ATCC 29247.........87 
A-8 Minimum Inhibitory Concentration (MIC) of lemongrass stem against
Staphylococcus aureus ATCC 29247................................................................................87 
A-9 Minimum Bactericidal Concentration (MBC) of lemongrass stem against
Staphylococcus aureus ATCC 29247................................................................................88 
A-10 Inhibitory zone of lemongrass stems against Staphylococcus aureus ATCC A35548......89 
A-11 Minimum Inhibitory Concentration (MIC) of lemongrass stem against
Staphylococcus aureus ATCC A35548.............................................................................89 
A-12 Minimum Bactericidal Concentration (MBC) of lemongrass stem against
Staphylococcus aureus ATCC A35548.............................................................................90 
B-1 Inhibitory zone of turmeric (fresh rhizomes).....................................................................91 
B-2 Minimum Inhibitory Concentration (MIC) of turmeric (fresh rhizomes).........................91 
B-3 Minimum Bactericidal Concentration (MBC) of turmeric (fresh rhizomes).....................91 
B-4 Inhibitory zone of turmeric (fresh rhizomes) against Staphylococcus aureus ATCC
SA12600-U........................................................................................................................92 
B-5 Minimum Inhibitory Concentration (MIC) of turmeric (fresh rhizomes) against
Staphylococcus aureus ATCC SA12600-U.......................................................................92 
B-6 Minimum Bactericidal Concentration (MBC) of turmeric (fresh rhizomes) against
Staphylococcus aureus ATCC SA12600-U.......................................................................92 
B-7 Inhibitory zone of turmeric (fresh rhizomes) against Staphylococcus aureus ATCC
SA29247............................................................................................................................93 
B-8 Minimum Inhibitory Concentration (MIC) of turmeric (fresh rhizomes)
Staphylococcus aureus ATCC SA29247...........................................................................93 
B-9 Minimum Bactericidal Concentration (MBC) of turmeric (fresh rhizomes)
Staphylococcus aureus ATCC SA29247...........................................................................94 
B-10 Inhibitory zone of turmeric (fresh rhizomes) against Staphylococcus aureus ATCC
35548..................................................................................................................................95 
B-11 Minimum Inhibitory Concentration (MIC) of turmeric (fresh rhizomes) against
Staphylococcus aureus ATCC 35548................................................................................95 
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B-12 Minimum Bactericidal Concentration (MBC) of turmeric (fresh rhizomes) against
Staphylococcus aureus ATCC 35548................................................................................95 
C-1 Inhibitory zone of turmeric (dried powder).......................................................................96 
C-2 Minimum Inhibitory Concentration (MIC) of turmeric (dried powder)............................96 
C-3 Minimum Bactericidal Concentration (MBC) of turmeric (dried powder).......................96 
C-4 Inhibitory zone of turmeric (dried powder) against Staphylococcus aureus ATCC
12600-U.............................................................................................................................97 
C-5 Minimum Inhibitory Concentration (MIC) of turmeric (dried powder) against
Staphylococcus aureus ATCC 12600-U............................................................................97 
C-6 Minimum Bactericidal Concentration (MBC) of turmeric (dried powder) against
Staphylococcus aureus ATCC 12600-U............................................................................97 
C-7 Inhibitory zone of turmeric (dried powder) against Staphylococcus aureus ATCC
29247..................................................................................................................................98 
C-8 Minimum Inhibitory Concentration (MIC) of turmeric (dried powder)
Staphylococcus aureus ATCC 29247................................................................................98 
C-9 Minimum Bactericidal Concentration (MBC) of turmeric (dried powder)
Staphylococcus aureus ATCC 29247................................................................................98 
C-10 Inhibitory zone of turmeric (dried powder) against Staphylococcus aureus ATCC
35548..................................................................................................................................99 
C-11 Minimum Inhibitory Concentration (MIC) of turmeric (dried powder) against
Staphylococcus aureus ATCC 35548................................................................................99 
C-12 Minimum Bactericidal Concentration (MBC) of turmeric (dried powder) against
Staphylococcus aureus ATCC 35548................................................................................99 

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LIST OF FIGURES
Figure page

2-1 Chemical structure of Citral (C H O) (3, 7-dimethyl-2, 6-octadienal)...........................50 
10 16
2-2 Chemical structure of Curcumin (C H O )....................................................................50 
21 20 6
3-1 Lemongrass (Cymbopogon citratus) plants.......................................................................57 
3-2 Turmeric (Curcuma longa) rhizomes................................................................................57 
3-3 Lemongrass leaves.............................................................................................................58 
3-4 Lemongrass stem...............................................................................................................58 
3-5 Inhibitory zone of lemongrass stem oven dried, hexane extracts on Staphylococcus
aureus ATCC 29247..........................................................................................................59 

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