A Novel Optimization Algorithm and Other Techniques in Medicinal Chemistry
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A NOVEL OPTIMIZATION ALGORITHM AND OTHER TECHNIQUES IN MEDICINAL CHEMISTRY by Radleigh G. Santos A Dissertation Submitted to the Faculty of The Charles E. Schmidt College of Science in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Florida Atlantic University Boca Raton, Florida May 2012 A NOVEL OPTIMIZATION ALGORITHM AND OTHER TECHNIQUES IN MEDICINAL CHEMISTRY by RadIeigh G. Santos This dissertation was prepared under the direction ofthe candidate's dissertation advisor, Dr. Dragan RaduIovic, Department of Mathematics, and has been approved by the members ofhis supervisory committee. It was submitted to the faculty ofthe Charles E. Schmidt College of Science and was accepted in partial fulfillment of the requirements for the degree ofDoctor ofPhilosophy. SUPERVISORY COMMITIEE: ~'"~-iC-'-Ph-.-O-.------ Di~i~' Richard Houghten, Ph.D. I• Wi ham Kalies, Ph.O. ..., 41~.·~,3._ Hongwei Long,Ph.D. =t- .t.;, ~ Rainer Steinwandt, Ph.D. College of Science ii ACKNOWLEDGEMENTS Since grade school mathematics has always been a joy and inspiration to me, and I am honored to be among the ranks of the highest level of education in the field. I could not have gotten this far were it not for countless people who have been in my life. These are but a notable few who deserve some credit for my achievement: I would like to thank all professors, mathematics or otherwise, from whom I have had the privilege to learn during my time at MIT, Georgia Tech, and FAU. Special thanks to scientists I continue to be privileged to work with at TPIMS: Marc Guilianatti, Jose Medina-Franco, Karina Martinez-Mayorga, Clemencia Pinilla, Valeria Judkowski, Dmitriy Minond, Joanna Davies, and Richard Houghten. I am grateful to my committee members William Kalies, Hongwei Long, and Rainer Steinwandt. Thank you also to Lee Klingler for his support during the final months of the process. Most of all I am thankful for being able to work with my advisor Dragan Radulovic, with whom I have never ceased to enjoy our shared enthusiasm over applied mathematics. Most of all I would like to thank the friends and family who were constant sources of support for me. Thanks to my grandmother Avee. Love, gratitude, and thanks to my wonderful sister Marlisa, who has always been there for me, my brother-in-law Randy, and to my Mother, who always has my back. And finally to my “Mathematical Muse” Denia, my deepest love and thanks, for supporting and believing in me even when I did not. iii ABSTRACT Author: Radleigh G. Santos Title: A Novel Optimization Algorithm and Other Techniques in Medicinal Chemistry Institution: Florida Atlantic University Dissertation Advisor: Dr. Dragan Radulovic Degree: Doctor of Philosophy Year: 2012 In this dissertation we will present a stochastic optimization algorithm and use it and other mathematical techniques to tackle problems arising in medicinal chemistry. In Chapter 1, we present some background about stochastic optimization and the Accelerated Random Search (ARS) algorithm. We then present a novel improvement of the ARS algorithm, Directed Accelerated Random Search (DARS), motivated by some theoretical results, and demonstrate through numerical results that it improves upon ARS. In Chapter 2, we use DARS and other methods to address issues arising from the use of mixture-based combinatorial libraries in drug discovery. In particular, we look at models associated with the biological activity of these mixtures and use them to answer questions about sensitivity and robustness, and also present a novel method for determining the integrity of the synthesis. Finally, in Chapter 3 we present an in-depth analysis of some statistical and mathematical techniques in combinatorial chemistry, including a novel probabilistic approach to using structural similarity to predict the activity landscape. iv A NOVEL OPTIMIZATION ALGORITHM AND OTHER TECHNIQUES IN MEDICINAL CHEMISTRY LIST OF TABLES ......................................................................................................... vii LIST OF FIGURES ........................................................................................................ ix INTRODUCTION ........................................................................................................... 1 CHAPTER 1 A DIRECTED ACCELERATED RANDOM SEARCH ALGORITHM ........... 3 Definitions and Assumptions ............................................................................... 3 Pure Random Search ............................................................................................ 5 Accelerated Random Search ................................................................................ 7 The Finite Descent ARS Algorithm ............................................................... 8 Limitations of Accelerated Random Search ................................................ 11 Directed Accelerated Random Search ............................................................... 15 Directional Information Present in the ARS Visit Record........................... 15 The DARS Heuristic .................................................................................... 19 Numerical Results .............................................................................................. 23 Demonstrative Function ............................................................................... 24 Benchmark Functions .................................................................................. 26 Systems of Equations ................................................................................... 31 The Domains of Linear and Nonlinear Programming Problems ................. 36 Conclusion ......................................................................................................... 41 2 OPTIMIZATION AND NUMERICAL MODELING IN MEDICINAL CHEMISTRY .................................................................................................... 44 Introduction ........................................................................................................ 44 Biological Activity ....................................................................................... 44 Mixture-Based Combinatorial Libraries ...................................................... 45 The Modeling of Chemical Mixtures ................................................................. 47 The Harmonic Mean Model ......................................................................... 48 Implications of the Harmonic Mean Model ................................................. 55 Extension of the Harmonic Mean Model ..................................................... 62 Determining the Integrity of Novel Mixture-Based Combinatorial Libraries ... 66 Experimental Synthesis Procedure .............................................................. 67 v Determining the Proper Reagent Ratio ........................................................ 68 Differences in Reaction Rate Caused by Multiple Simultaneous Reactions ...................................................................................................... 71 Differences in Reaction Rate Caused by Different On-Resin Amino Acids ............................................................................................................ 73 Conclusion ......................................................................................................... 79 3 STATISTICAL AND PROBABILISTIC METHOD IN COMPUTATIONAL CHEMISTRY ................................................................. 80 Introduction ........................................................................................................ 80 The Structural-Activity Relationship ........................................................... 80 The Biological Target for Study .................................................................. 82 Standard Methodology ....................................................................................... 84 Description of Data Set ................................................................................ 84 2D and 3D Structural Similarity .................................................................. 85 Property Similarities .................................................................................... 85 Activity Similarity ....................................................................................... 87 Activity Landscape with SAS Maps ............................................................ 87 Consensus SAS Map .................................................................................... 90 Results and Discussion of Standard Methods .................................................... 91 Distribution of Fingerprint Similarity Measures.......................................... 91 Correlation Between Molecular Similarities ............................................... 91 The Activity Landscape ............................................................................... 93 Consensus Models of the Activity Landscape: Consensus SAS Maps...... 107 Dual-Parasite SAR and Consensus Selectivity Cliffs ................................ 108 Conclusions and Perspectives .................................................................... 109 Predictivity Analysis of Structural and Property Similarities .......................... 111 Threshold Determination Heuristic............................................................ 111 Testing Methodology ................................................................................