Isolation, Synthesis and Structure −−−Activity Relationship Study of Anticancer and Antimalarial Agents from Natural Products Yumin Dai Dissertation submitted to the faculty of Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry David G. I. Kingston, chair Harry W. Gibson Richard D. Gandour Webster L. Santos Oct. 29 th , 2013 Blacksburg, Virginia Keywords: Natural Products, Anticancer, Antimalarial, Acetogenins, Sesquiterpenoid, Flavonoid, Bufadienolide, Triterpene saponin, Anthraquinone. Copyright 2013, Yumin Dai Isolation, Synthesis and Structure −−−Activity Relationship Study of Anticancer and Antimalarial Agents from Natural Products Yumin Dai Abstract The Kingston group's engagement in an International Cooperative Biodiversity Group (ICBG) program and a collaborative research project established between Virginia Tech and the Institute for Hepatitis and Virus Research (IHVR) has focused on the search for bioactive natural products from tropical forests in both Madagascar and South Africa. As a part of this research, a total of four antiproliferative extracts were studied, leading to the isolation of fourteen novel compounds with antiproliferative activity against the A2780 human ovarian cancer line. One extract with antimalarial activity was studied, which led to the isolation of two new natural products with antiplasmodial activity against a drug-resistant Dd2 strain of Plasmodium falciparum . The plants and their secondary metabolites are discussed in the following order: two new antiproliferative acetogenins from a Uvaria sp. (Annonaceae); two new antiproliferative calamenene-type sesquiterpenoids from Sterculia tavia (Malvaceae); two new antiproliferative triterpene saponins from Nematostylis anthophylla (Rubiaceae); six new antiproliferative homoisoflavonoids and two new bufatrienolides from Urginea depressa (Asparagaceae); and two new antiplasmodial anthraquinones from Kniphofia ensifolia (Asphodelaceae). The structures of all these compounds were determined by analysis of their mass spectrometric, 1D and 2D NMR, UV and IR spectroscopic and optical rotation data. Other than structural elucidation, this work also involved bioactivity evaluations of all the isolates, as well as total synthesis of the two antiproliferative sesquiterpenoids, and a structure −activity relationship (SAR) studies on the antiplasmodial anthroquinones. iii Dedication I would like to dedicate this dissertation to my parents Mingliang Dai and Huiling Fan, and my brother Wei Zhang for their love and support. iv Acknowledgement I think the most chronologically accurate place to begin my dissertation acknowledgements is with my parents, who long, long ago introduced me to the periodic table that hung on the wall, describing it as a "building" and telling me there were different residents living in each "house". I still remember my mom explained who they were, while my father created a doggerel in our dialect, which included all those residents. I think that is my earliest touch of chemistry. Thanks Mom and Dad for your love, and for allowing a little boy’s fascination with the world to lead him into science and never stopping believing in him. While my family may have set the stage, the ones who opened the curtain were my high school chemistry teachers, Miss Juan Zheng and Mr. Yunzhong Mao. Under their guidance, I came to know how to design and conduct a chemistry experiment independently. And I still remember how happy I was when my first research paper was published in a local magazine. Later on, Professor Min Chen from China Agricultural University accepted me as an undergraduate student in her laboratory. I owe Prof. Chen a lot for teaching, encouraging, and being forgiving with all the mistakes I made during that time. I was not totally involved in chemistry until I finished my M.Sc studies in the Department of Food Science and Technology at Virginia Tech. Instead of moving to the Ohio State University, today I still think I have made a correct decision to join chemistry department at VT, where I met with my advisor Dr. David Kingston, who has had the most influence on my career; thus the most important acknowledgement must go to him. Elegance and professionalism are the two words that come to mind when someone mentions Dr. Kingston. He continually taught me the v knowledge of chemistry from all aspects, and forced me to learn how to learn and discover on my own, which is truly the goal of a Ph.D. Rather than an advisor, I respect Dr. Kingston more as a grandfather. Besides the science, he kept encouraging me to get rid of flaws, refresh myself and be confident. Thanks Dr. Kingston for your tolerance, forgiveness and support. My committee, Dr. Webster Santos, Dr. Harry Gibson and Dr. Richard Gandour provided invaluable resources during my study in the past three years. I learned and will always remember the word "punctiliousness" from Dr. Gandour, and I think it is the right attitude a real scientist should possess. Meanwhile, I really appreciate that Dr. Gandour gave me the good suggestions on speaking good English. Dr. Gibson did not talk much, but his words always led me to think in depth. I still remember his word "ask yourself what your aim is when make a presentation" once I spent only 31 minutes to finish a seminar with 60 slides. For Dr. Santos, almost all my knowledge of organic synthesis is directly from him. Thanks Dr. Gandour, Dr. Gibson and Dr. Santos for your selflessness. The next acknowledgement should be delivered to Dr. Liva Harinantenaina, who directly taught me the basic knowledge and techniques in the field of natural products. I enjoyed the past three years working with him, getting trained by him, and also learning from him. Without his help, my exposure to natural products may have experienced more obstacles along the way. Much closer to a friend, he always acted as a big brother to me, including sharing life experiences, the tricks during the social time, etc. Thanks Liva for your help. The same thanks should go to all my collaborators, including Dr. Yongchun Shen from Eisai Inc. for anticancer bioassays, Dr. Michael Goetz from the Natural Products Discovery Institute vi for the extract supply, Dr. Maria Caserra from the Department of Biochemistry for the antimalarial assay, and Dr. Giulio Paciotti from CytImmune for coordinating the AZ project, etc. I would also like to thank the Chemistry staff for all of their help over the past three years, especially Dr. Hugo Azumendi, Mr. Bill Bebout and Mr. Geno Iannaccone for NMR and MS service. I would like to thank all of my lovely labmates who have befriended me. Dr. Shugeng Cao, Dr. Yanpeng Hou, Dr. Jun Qi, Dr. Jielu Zhao, Dr. Ende Pan, Dr. Qiaohong Chen and Mr. Zhibing Xu left me a lot of treasure and valuable suggestions before they left the group. The current group members, including Karen Iannaccone, Peggy Brodie, Yixi Liu, Alex Eaton, Amrapali Dengada, Chris Presley, Qingxi Su and Long Xia always gave me a hand when I needed it. Peggy Brodie took care of all the cell culture bioassays involved in my research, and she helped me proofread all my papers. I would especially like to thank Yixi Liu for all of the discussions, laughter, lunches, tailgates, and social hours. Every time, when my mood was extremely down, she pulled me out from the valley in time. Special acknowledgement should also be delivered to Long Xia for the happiness, and optimism he brought me both in and out of work. Thanks Yixi, thanks Long, thanks all my group members. I always knew that someone would be there for me to talk to and I hope that our paths cross again someday. Lastly, I would like to thank all the friends I met at Virginia Tech, including Lei Pan, Liyun Ye, Jie Zhu, Wenrui Zhang, Bohan Bao, Xueyan Zheng, Xiangtao Meng, Yufeng Ma, Ran Liu, Xinyi Tan, Haoyu Liu, Tinghui Li, Ming Wang, Yongle Du, Xiaoyan Jia and Shi Yu. My life became wonderful with you guys in the past five years staying in Blacksburg. And also please forgive me for any names not mentioned here. vii Table of Contents Abstract ............................................................................................................................................ii Dedication .......................................................................................................................................iv Acknowledgement............................................................................................................................v Table of Contents ......................................................................................................................... viii List of Abbreviations........................................................................................................................x List of Tables ...................................................................................................................................xi List of Schemes ............................................................................................................................. xii List of Figures .............................................................................................................................. xiii Chapter 1: Introduction ..................................................................................................................1 1.1 Cancer and Anticancer Agents from Natural Products.......................................................1 1.2 Malaria