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Annalesai477liimatainen.Pdf (9.300Mb) TURUN YLIOPISTON JULKAISUJA ANNALES UNIVERSITATIS TURKUENSIS SARJA - SER. A I OSA - TOM. 477 ASTRONOMICA - CHEMICA - PHYSICA - MATHEMATICA PHENOLICS OF THE INNER BARK OF SILVER BIRCH: CHARACTERIZATION AND INTRASPECIFIC VARIATION by Jaana Liimatainen TURUN YLIOPISTO UNIVERSITY OF TURKU Turku 2013 From the Laboratory of Organic Chemistry and Chemical Biology, Department of Chemistry, University of Turku, Finland Supervised by Docent Dr Maarit Karonen Department of Chemistry University of Turku Turku, Finland Docent Dr Jari Sinkkonen Department of Chemistry University of Turku Turku, Finland Custos Professor Dr Juha-Pekka Salminen Department of Chemistry University of Turku Turku, Finland Reviewed by Professor Dr Irene Mueller-Harvey School of Agriculture, Policy and Development University of Reading Reading, U.K. Docent Dr Hannu Maaheimo VTT Technical Research Centre of Finland Helsinki, Finland Opponent Professor Dr Stefan Willför Department of Chemical Engineering Åbo Akademi University Åbo, Finland The originality of this thesis has been checked in accordance with the University of Turku quality assurance system using the Turnitin OriginalityCheck service. ISBN 978-951-29-5589-3 (PRINT) ISBN 978-951-29-5590-9 (PDF) ISSN 0082-7002 Painosalama Oy – Turku, Finland 2013 Table of Contents 3 TABLE OF CONTENTS PREFACE.............................................................................................................................. 5 ABSTRACT .......................................................................................................................... 7 LIST OF ORIGINAL PUBLICATIONS .............................................................................. 8 ABBREVIATIONS ............................................................................................................... 9 1. INTRODUCTION ........................................................................................................... 11 2. LITERATURE REVIEW ................................................................................................ 15 2.1. Phenolic compounds in the different plant organs of silver birch ............................ 15 2.1.1. Leaves ............................................................................................................... 16 2.1.2. Leaf surface ...................................................................................................... 16 2.1.3. Outer bark ......................................................................................................... 17 2.1.4. Inner bark .......................................................................................................... 17 2.1.5. Wood ................................................................................................................. 17 2.1.6. Knotwood ......................................................................................................... 18 2.1.7. Roots of seedlings ............................................................................................. 18 2.2. Functions of phenolics ............................................................................................. 18 2.2.1. Pollinator and seed disperser attractants ........................................................... 18 2.2.2. Herbivore and pathogen deterrents and inhibitors ............................................ 19 2.2.3. Nutrient cycling ................................................................................................ 20 2.2.4. Protection against UV radiation ........................................................................ 21 2.2.5. Autumn colors .................................................................................................. 22 2.3. Advanced characterization methods for the analysis of phenolics ........................... 22 2.3.1. LC-MS .............................................................................................................. 23 2.3.2. NMR spectroscopy ........................................................................................... 26 2.3.3. CD spectroscopy ............................................................................................... 30 3. AIMS OF THE STUDY .................................................................................................. 32 4. MATERIALS AND METHODS .................................................................................... 33 4.1. Plant material ........................................................................................................... 33 4.2. Extraction of the inner bark ...................................................................................... 33 4.2.1. Large scale extraction ....................................................................................... 33 4.2.2. Small scale extraction ....................................................................................... 34 4.3. Fractionation and isolation of the inner bark phenolics ........................................... 34 4 Table of Contents 4.4. Radical scavenging assay ......................................................................................... 35 4.5. Acid−butanol assay .................................................................................................. 36 4.6. HPLC-DAD analysis ................................................................................................ 36 4.7. HPLC-MS analysis ................................................................................................... 36 4.8. FAB-MS ................................................................................................................... 37 4.9. NMR spectroscopy ................................................................................................... 37 4.10. CD spectroscopy .................................................................................................... 38 4.11. Computational methods ......................................................................................... 39 5. RESULTS AND DISCUSSION ...................................................................................... 40 5.1. Extraction of the phenolic compounds ..................................................................... 40 5.2. Characterization of the phenolic compounds ........................................................... 40 5.2.1. RP-HPLC-DAD/ESI-MS analysis .................................................................... 43 5.2.2. Hydrophilic interaction HPLC-ESI-MS analysis .............................................. 47 5.2.3. NMR spectroscopy ........................................................................................... 51 5.2.4. Assignment of absolute configuration .............................................................. 62 5.3. Quantification and seasonal variation ...................................................................... 73 5.4. Induction of phenolics by wounding ........................................................................ 74 6. CONCLUSIONS ............................................................................................................. 77 REFERENCES .................................................................................................................... 78 ORIGINAL PUBLICATIONS ............................................................................................ 91 Preface 5 PREFACE This work was carried out in the Laboratory of Organic Chemistry and Chemical Biology at the Department of Chemistry, University of Turku, since May 2006. The plant material was mainly collected from the Botanical Garden of the University of Turku. First of all, I want to thank professors Kalevi Pihlaja and Juha-Pekka Salminen for providing the high-grade facilities to carry out this research. The former professor Kalevi Pihlaja first introduced me to the field of environmental chemistry and chemistry of natural products. I am grateful for his contacts, encouragement and long-lasting interest towards my results which have continued despite his retirement. The present professor Juha-Pekka Salminen was a big help in the early years of this Ph.D. work when our section was under changes. We had inspiring discussions about the analysis of phenolics and the world of science in general during the uncrowded coffee breaks. I admire his dedication to his work and I am grateful to him for his patience and allowing me to spend so many years with this topic. My deepest gratitude goes equally to my supervisors Dr. Maarit Karonen and Dr. Jari Sinkkonen. They have encouraged and skillfully instructed me all these years. Maarit have taught me a lot about the analysis of phenolic compounds. She has helped me in the scientific writing and revised my manuscripts with an admirable perseverance. Jari is an amazing scientist, who has an exceptional ability to teach difficult things understandably. He has taught me the most of what I know about the NMR and computational methods. Maarit and Jari have a big heart and they are both full of new ideas. I could not have wished for better supervisors. I want to thank Dr. Marjo Helander for letting me to use the birch clones she had planted on the Botanical Garden. In addition, she did the statistical analysis and helped whenever a perspective of a biologist was needed. I am grateful for Dr. Petri Tähtinen for his help on ECD spectroscopy and on stereochemistry in general. I also wish to thank Dr. Jeff Ahern for kindly reviewing the
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