Clemson University TigerPrints All Dissertations Dissertations 8-2009 UNDERSTANDING THE ANTIOXIDANT MECHANISM OF INORGANIC SELENIUM, OXO- SULFUR, AND POLYPHENOL COMPOUNDS, AND THE BIOLOGICAL IMPLICATIONS OF FUNCTIONALIZED NANOPARTICLES Ria Ramoutar Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_dissertations Part of the Inorganic Chemistry Commons Recommended Citation Ramoutar, Ria, "UNDERSTANDING THE ANTIOXIDANT MECHANISM OF INORGANIC SELENIUM, OXO- SULFUR, AND POLYPHENOL COMPOUNDS, AND THE BIOLOGICAL IMPLICATIONS OF FUNCTIONALIZED NANOPARTICLES" (2009). All Dissertations. 430. https://tigerprints.clemson.edu/all_dissertations/430 This Dissertation is brought to you for free and open access by the Dissertations at TigerPrints. It has been accepted for inclusion in All Dissertations by an authorized administrator of TigerPrints. For more information, please contact [email protected]. UNDERSTANDING THE ANTIOXIDANT MECHANISM OF INORGANIC SELENIUM, OXO- SULFUR, AND POLYPHENOL COMPOUNDS, AND THE BIOLOGICAL IMPLICATIONS OF FUNCTIONALIZED NANOPARTICLES A Dissertation Presented to The Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Chemistry by Ria R. Ramoutar August 2009 Accepted by: Dr. Julia Brumaghim, Committee Chair Dr. Kenneth A. Christensen Dr. William T. Pennington Dr. Jason McNeill i ABSTRACT Inorganic selenium, oxo-sulfur, and polyphenol compounds are found in foods and dietary supplements, and are recognized for their nutritional benefits and their potential to treat or prevent diseases caused by oxidative stress. In our experiments to determine the effects of inorganic selenium compounds on iron-mediated DNA damage, Na2SeO3 and SeO2 exhibit antioxidant and pro-oxidant activities depending on concentrations of both the compound and hydrogen peroxide. Additional experiments demonstrate that iron coordination is a novel mechanism responsible for the observed + activities. In similar experiments, oxo-sulfur compounds prevent Cu /H2O2-mediated 2+ DNA damage significantly more than DNA damage from Fe /H2O2. UV-vis and gel electrophoresis experiments also confirm that copper coordination is primarily responsible for the DNA damage inhibition, a novel mechanism that extends to all tested sulfur and selenium antioxidants. Electrospray ionization mass spectroscopy indicates that these sulfur and selenium compounds generally bind Cu+ in a 1:1 ratio. Combinations of bioactive components in foods can affect activity of antioxidants. For example, adding one equivalent of caffeine to polyphenols has no effect on DNA damage prevention by epigallocatechin gallate, but significantly decreases the antioxidant ability of quercetin. In addition, DNA damage prevention studies on peach extracts indicate that genetically-modified peach cultivars prevent more DNA damage than unmodified cultivars. In contrast, tetraphenyl-porphyrin-doped conjugated polymer dot nanoparticles cause DNA backbone and base damage upon irradiation, suggesting that these nanoparticles may be efficient photosensitizers for photodynamic therapy i (PDT). Our studies also show H2O2 formation by and iron association with polyethylene glycol (PEG) and PEG-functionalized beads at biologically-relevant concentrations. 2+ Since Fe and H2O2 react to form damaging hydroxyl radical, use of PEG-functionalized nanoparticles in medical applications may cause oxidative stress. Overall, this work has elucidated of antioxidant and pro-oxidant mechanisms of inorganic selenium, oxo-sulfur, and polyphenol compounds, as well as the potential toxicity of functionalized nanomaterials used for PDT and other medical applications. ii DEDICATIONS I dedicate this dissertation to my parents, Phagoo and Gowra Ramoutar, and sisters Reshma and Asha for their encouragement, love and support that allowed me to achieve this measure of academic success. The strength and support of my family made me believe that all things are possible through hard work and dedication. iii ACKNOWLEDGEMENTS Firstly, I would like to thank my advisor, Dr. Julia L. Brumaghim, for allowing me to participate in research projects in the very interesting and exciting field of bioinorganic chemistry. I would like to thank Dr. Brumaghim for her continuous mentoring, guidance, and support throughout my graduate academic career. I am especially grateful for the invaluable knowledge and experience gained from her. I would also like to thank Mrs. Barbara Lewis for making my experience as a teaching assistant very interesting and enjoyable. It was truly a pleasure working under her supervision. Special thanks to both Joy Castro and Carolyn Quarles for training and assisting me in both ICP and ESI mass spectroscopies. I would like to acknowledge my collaborators, including Dr. Jason McNeill, Dr. Albert Abbott, and Dr. Pamela Riggs- Gelasco. I would especially like to thank my family and friends in Trinidad and Tobago and Canada for their continuous love, support, and guidance, which has been invaluable to me throughout my academic career while in the United States. I would also like to acknowledge Rajashree Sathyamurthy, Mark Bradshaw, Erin Battin, and Jared Knutt, for their ongoing support and friendship. Special thanks to the Brumaghim group members, including Andrea Verdan, for their witty comments, humor, support and friendship, which made research an enjoyable experience. iv TABLE OF CONTENTS ABSTRACT......................................................................................................................... i DEDICATIONS.................................................................................................................iii ACKNOWLEDGEMENTS...............................................................................................iii TABLE OF CONTENTS................................................................................................... iv LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ........................................................................................................... xi CHAPTER 1. A REVIEW OF THE ANTIOXIDANT AND ANTICANCER PROPERTIES AND MECHANISMS OF INORGANIC SELENIUM, OXO-SULFUR, AND OXO-SELENIUM COMPOUNDS Introduction .................................................................................................. 1 Selenium bioavailability, related pathologies, and biological effects .......... 8 Pathologies associated with selenium deficiency and toxicity..................... 9 Antioxidant and anticancer activities of inorganic selenium compounds.. 13 Selenium speciation and anticancer activity .............................................. 16 Mechanisms of antioxidant and anticancer activity for inorganic selenium compounds ............................................................................................. 17 Bioavailability and activity of oxo-sulfur and oxo-selenium compounds . 19 Antioxidant and pro-oxidant effects of oxo-sulfur compounds in disease prevention .............................................................................................. 23 Antioxidant and pro-oxidant mechanisms of oxo-sulfur compounds ........ 28 Oxo-selenium compounds.......................................................................... 32 Conclusions ................................................................................................ 33 References .................................................................................................. 36 2. EFFECTS OF INORGANIC SELENIUM COMPOUNDS ON OXIDATIVE DNA DAMAGE Introduction ................................................................................................ 56 Results ........................................................................................................ 59 Discussion .................................................................................................. 70 Conclusions ................................................................................................ 76 Materials and methods................................................................................ 77 References .................................................................................................. 91 v 3. INVESTIGATING THE ANTIOXIDANT PROPERTIES OF OXO-SULFUR COMPOUNDS ON METAL-MEDIATED DNA DAMAGE Introduction ................................................................................................ 95 Results and discussion................................................................................ 98 Conclusions .............................................................................................. 116 Materials and methods.............................................................................. 117 References ................................................................................................ 130 4. INVESTIGATING THE ABILITY OF π-CONJUGATED POLYMER NANOPARTICLES TO PROMOTE OXIDATIVE DNA DAMAGE Introduction .............................................................................................. 135 Toxicity of nanoparticles.......................................................................... 139 Results and discussion.............................................................................. 140 Conclusions .............................................................................................