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Development of a GC-MS method and analysis of phenolic acids in fruit and spice matrices and evaluation of their antioxidant capacity By Ebtihal Yaqoob Khojah A thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy Supervisor: Dr. Jayashree Arcot Co-supervisor: Dr. Martin Bucknall School of Chemical Engineering The University of New South Wales Sydney, Australia August 2010 COPYRIGHT STATEMENT 'I hereby grant the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstract International (this is applicable to doctoral theses only). I have either used no substantial portions of copyright material in my thesis or I have obtained permission to use copyright material; where permission has not been granted I have applied/will apply for a partial restriction of the digital copy of my thesis or dissertation.' Signed d d d d d dddd d ~ d dd dO d W OO O O dOdOO Date AUTHENTICITY STATEMENT 'I certify that the Library deposit digital copy is a direct equivalent of the final officially approved version of my thesis. No emendation of content has occurred and if there are any minor variations in formatting, they are the result of the conversion to digital format.' Signed · ··· · · · · · · ·· · ··· ~dd " ~~- •••• • •••••••• • • • ••• ••• • •• Date ORIGINALITY STATEMENT 'I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.' Signed ................ :-::::=...... d~ .......................... Date ··· ······· ··································-···················· PLEASE TYPE THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: Khojah First name: Ebtihal Other name/s: Abbreviation for degree as given in the University calendar: PhD School: Chemical Sciences and Engineering Faculty: Engineering Title: Development of method and analysis of phenolic acids in fruit and spices by GC-MS and evaluation of their antioxidant capacity Abstract 349words maximum The aim of the present study was to develop a specific and quantitative assay to determine the individual concentrations of naturally occurring phenolic acids and its metabolites in food; then evaluate the antioxidant capacity of the quantified phenolic acids using different assays. A GC/MS method for the quantification of ten commonly available phenolic acids in plant food was developed. Target analytes were the benzoic acid based phenolic acids - anisic, gallic, p-hydroxy benzoic, a-salicylic, protocatechuic, and vanillic acids, together with the cinnamic acid based phenolic acids - caffeic, p­ coumaric, ferulic and sinapinic acids. These compounds have been identified by retention time and comparison of electron impact mass spectra. Deuterated phenolic acid was used as an internal standard to achieve reliable quantification. Purification was accomplished using Cl8 solid phase extraction cartridges (ENVI Chrome P, Supelco). Sample extracts were derivatized prior to GC-MS analysis using BSTFA and pyridine (4:1 VN); the reaction conditions for the derivatization process were optimized. Resolution and quantitation of all compounds were excellent with linear calibration curves over a wide range 0-500 nglml 2 and correlation coefficients {R ) of 0.999. Relative standard deviation (RSD) and respond factor (RF) were satisfactory (?:1.1 and >3 respectively) and within the acceptable limits ofbioanalytical method validation guideline. The adapted method was applied to different varieties of fresh and sundried Saudi Arabian dates namely as well as Achacha fruit and selected eleven spices. The results revealed that phenolic acids are present in plant foods mostly in bound form as esters or glycosides. The lipophilic and hydrophilic antioxidant activities of all selected samples were examined using ORAC assay. In addition the antioxidant capacity of the identified free and bound phenolic acids was measured by different assays including ORAC, ABTS, DPPH and FCR. The results indicate that lipophilic antioxidants do not play roles as important as hydrophilic antioxidants and high phenolic acids content was not correlated with high antioxidant activity. In conclusion the method presented is robust, safe, sensitive and generally applicable to the analysis of free and bound phenolic acids in food samples. The data obtained is sufficiently reliable to be included in food composition databases. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). Signature Witness Date The University recognises that there may be exceptional circumstances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and re uire the a roval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award: THIS SHEET IS TO BE GLUED TO THE INSIDE FRONT COVER OF THE THESIS 2 ORIGINALITY STATEMENT ‗I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.‘ Signed …………………………………………….............. Date …………………………………………….............. 3 Acknowledgment First of all, thanks to Allah S. W. T for his mercy and guidance in giving me full strength to complete this project. Being human I have many days where I feel like I have failed each of them. But deep inside, I hear little reminders that tell me it is okay, no one is perfect- just continue to move forward and don't worry about yesterday. I believe each of us have certain areas within our minds that need different encouragement, or need to be persuaded differently in a certain way when it comes to accomplishing different goals we set for ourselves. Each person in my life has done that for me; one is my Dear mother, the other is my supervisor Dr. Jayashree Arcot and one is someone very close to me my husband Mr. Ibrahim Khan. I would like to acknowledge all those who played a direct or indirect role in the progress and completion of this thesis. To begin with, The Saudi Arabian Government representative in Taif University who gave me scholarship to score this degree and funded the project. To my supervisor Associate Professor Dr. Jayashree Arcot I owe the greatest debt of gratitude. I am so honored with her supervision and teaching me a direction on my path that would forever be with me. She gave me the freedom to explore on my own and at the same time the guidance to recover when my steps faltered. She taught me how to question thoughts and express ideas. Her patience and support helped me overcome many critical situations and finish this journey. I hope that one day I would become as good an advisor to my students as Dr. Arcot has been to me. I am grateful to my co-supervisor Dr. Martin Bucknall from the Bioanalytical Mass Spectrometric Facility (BMSF) for his invaluable input and contribution to my research; his extensive efforts in helping me to formulate my objectives, the time and support he has so generously given to me have been invaluable. I‘ll not forget to acknowledge Dr. Alice Lee for all her advice; the lab manager Mr. Camillo Taraborrelli for his assistance and all technical advice. A special acknowledgment must go to the person I missed, my father Yaqoob Khojah, who instilled in me the love of learning and curiosity about the world around me in many and various ways, May Allah grace him. 4 I am indebted to my mother Mrs. Khadejah Khojah; my first teacher in my life. She sets high standards for her children and encourages and guides us with her love to meet those standards.

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