antioxidant and antimicrobial compounds from the marine algae padina antillarum chia pooi yee

207 Pages·2011·26.1 MB·English

ANTIOXIDANT AND ANTIMICROBIAL COMPOUNDS
FROM THE MARINE ALGAE PADINA ANTILLARUM

CHIA POOI YEE

MASTER OF SCIENCE

FACULTY OF SCIENCE
UNIVERSITI TUNKU ABDUL RAHMAN
DECEMBER 2010
ANTIOXIDANT AND ANTIMICROBIAL COMPOUNDS
CHIA POOI YEE
2010
FROM THE MARINE ALGAE PADINA ANTILLARUM
ANTIOXIDANT AND ANTIMICROBIAL COMPOUNDS FROM THE
MARINE ALGAE Padina antillarum

By

CHIA POOI YEE

A thesis submitted to the Department of Chemical Science,
Faculty of Science,
Universiti Tunku Abdul Rahman,
in partial fulfillment of the requirements for the degree of
Master of Science
December 2010
ABSTRACT

ANTIOXIDANT AND ANTIMICROBIAL COMPOUNDS FROM THE
MARINE ALGAE Padina antillarum

Chia Pooi Yee

The antioxidant property and antimicrobial activity of extracts of the
brown marine algae Padina antillarum were studied. Different extraction
methods were applied in order to extract antioxidant and antimicrobial
compounds. For the purpose of extracting antioxidant compounds, a 50%
aqueous methanol extract of freeze-dried P. antillarum was subjected to liquid-
liquid partitioning. The three extracts (chloroform, ethyl acetate and water)
which were obtained from partitioning were subjected to total phenolic content
and radical scavenging activity assays. The ethyl acetate extract showed the
highest antioxidant activity and was subjected to activity-guided fractionation.
Instrumental analyses (Gas Chromatography-Mass Spectrometer, 1H-and 13C-
Nuclear Magnetic Resonance Spectrometer) revealed the presence of
phloroglucinol (1,3,5-trihydroxybenzene) in this extract. The radical
scavenging activity of phloroglucinol was compared to that of the known
antioxidant plant compounds, quercetin, ascorbic acid and tannic acid, and was
found to be weakest of the four in terms of free radical scavenging, ferric
reducing antioxidant power and chelating ability. Phloroglucinol had weak
activity against Staphylococcus aureus (ATCC 6538), Bacillus cereus (ATCC
11778), Pseudomonas aeruginosa (ATCC 27853), Klebsiella pneumoniae
(ATCC 13883), and Escherichia coli [both penicillin-sensitive (ATCC 25922)
and penicillin-resistant strains (ATCC 35218)]. Phloroglucinol had no activity
ii
towards leukemia cells (K562 cell line) and no detectable antifungal activity.
For extraction of antimicrobial compound, freeze-dried P. antillarum sample
was subjected to sequential extraction using organic solvents of increasing
polarity (i.e. hexane followed by diethyl ether, chloroform, ethyl acetate,
acetone, methanol and finally water). The hexane extract exhibited the highest
and most consistent inhibitory activity against P. aeruginosa with a mean
minimum inhibitory concentration (MIC, n=3) value of 0.625 mg/mL. Thus
this extract was selected for further in vitro bioassay-guided fractionation. The
structure of the partially-purified antimicrobial compound, which had a mean
MIC of 0.031 mg/mL, was elucidated by GC-MS, and found to be diisooctyl
phthalate.

iii
ACKNOWLEDGEMENTS

First and foremost, I would like to express my deepest gratitude to my
supervisor, Dr. Khoo Kong Soo and co-supervisor, Dr. Sit Nam Weng for their
guidance, opinion and advice throughout the completion of this project.

I would like to take this opportunity to thank Dr. Lim Yau Yan from
Monash University who guided me for the antioxidant assays. Unforgettably, I
also thank to UTAR lab assistants for providing apparatus and chemicals for
my project. I sincerely thank to Universiti Tunku Abdul Rahman for providing
Research Grant 6202/C06.

Big thanks to my partner, Ms. Lim Fei Shen for providing useful
information to me. I would like to show my special thanks to my family and
fellow friends for their support.

iv
DECLARATION

I hereby declare that the thesis is based on my original work except for
quotations and citations which have been duly acknowledged. I also declare
that it has not been previously or concurrently submitted for any other degree
at UTAR or other institutions.

Name ____________________________

Date _____________________________

v
APPROVAL SHEET

This thesis entitled “ANTIOXIDANT AND ANTIMICROBIAL
COMPOUNDS FROM THE MARINE ALGAE PADINA ANTILLARUM”
was prepared by CHIA POOI YEE and submitted as partial fulfillment of the
requirements for the degree of Master of Science at Universiti Tunku Abdul
Rahman.

Approved by:

___________________________
(Assoc. Prof. Dr.KHOO KONG SOO) Date:…………………..
Supervisor
Department of Chemical Science
Faculty of Science
Universiti Tunku Abdul Rahman

___________________________
(Assist. Prof. Dr. SIT NAM WENG) Date:…………………..
Co-supervisor
Department of Biomedical Science
Faculty of Science
Universiti Tunku Abdul Rahman

vi
FACULTY OF SCIENCE
UNIVERSITI TUNKU ABDUL RAHMAN

Date:

PERMISSION SHEET

It is hereby certified that CHIA POOI YEE (ID No: 07UEM08778) has
completed this thesis entitled “ ANTIOXIDANT AND ANTIMICROBIAL
COMPOUNDS FROM MARINE ALGAE PADINA ANTILLARUM” under
supervision of Assoc. Prof. Dr. Khoo Kong Soo (Supervisor) from the
Department of Chemical Science, Faculty of Science, and Assist. Prof. Dr. Sit
Nam Weng (Co-supervisor) from Department of Biomedical Science, Faculty
of Science.

I hereby give permission to the University to upload softcopy of my thesis in
pdf format into UTAR Institutional Repository, which will be made accessible
to UTAR community and public.

Yours truly,

____________________
(CHIA POOI YEE)

vii
TABLE OF CONTENTS

Page

ABSTRACT ii
ACKNOWLEDGEMENTS iv
DECLARATION v
APPROVAL SHEET vi
PERMISSION SHEET vii
TABLES OF CONTENTS viii
LIST OF TABLES xii
LIST OF FIGURES xv
LIST OF ABBREVIATIONS xix

CHAPTER

1.0 INTRODUCTION
1.1 Natural Products 1
1.2 Marine Natural Products 1
1.3 Seaweeds 3
1.4 Antioxidant 4
1.5 Antimicrobial Compounds 6
1.6 Hypothesis 7
1.7 Objectives 7

2.0 LITERATURE REVIEW
2.1 Bioactive Marine Natural Products 9
2.1.1 Phenols 10
2.1.2 Terpenes and Terpenoids 11
2.1.3 Steroids 13
2.1.4 Alkaloids 15
2.2 Seaweeds 17
2.2.1 Classification of Seaweeds 18
2.2.2 Uses of Seaweeds 19
2.3 Oxidative Stress 21
2.4 Free Radicals 22
2.5 Antioxidants 24
2.5.1 Natural and Synthetic Antioxidants 26
2.6 Classification of Medically Important Bacteria 29
2.7 The Action of Antimicrobial Drugs 31
2.8 Previous Research on Padina antillarum 32

3.0 MATERIALS AND METHODS
3.1 Sample Collection and Preparation 34
viii