Dual Mechanism Analgesia-Enhancing Agents
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Virginia Commonwealth University VCU Scholars Compass Theses and Dissertations Graduate School 2005 Dual Mechanism Analgesia-Enhancing Agents Shawquia Elithia Young Virginia Commonwealth University Follow this and additional works at: https://scholarscompass.vcu.edu/etd Part of the Chemicals and Drugs Commons © The Author Downloaded from https://scholarscompass.vcu.edu/etd/1166 This Thesis is brought to you for free and open access by the Graduate School at VCU Scholars Compass. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of VCU Scholars Compass. For more information, please contact [email protected]. O Shawquia Elithia Young, 2005 All Rights Reserved DUAL MECHANISM ANALGESIA-ENHANCING AGENTS A thesis submitted in partial fulfillment of the requiremehts for the degree of Master of Science at Virginia Commonwealth University. Shawquia Elithia Young Bachelor of Science, Hampton University, 2002 Director: Malgorzata Dukat, Ph.D. Department of Medicinal Chemistry Co-Director: Richard A. Glennon, Ph.D. Department of Medicinal Chemistry Virginia Commonwealth University Richmond, Virginia August 2005 Acknowledgements I would like to express my deepest gratitude to my'advisors Dr. Malgorzata Dukat and Dr. Richard Glennon for their wonderful guidance and teachings in the completion of this research. Their patience and honesty were greatly appreciated. I am also thankful to Dr. Anna Wesolowska for teaching me everything about the mouse tail-flick and hot- plate assays. I would like to thank Dr. Eliseu De Oliveira for being optimistic and patient while helping me in my synthesis. I want to give thanks to Dr. Richard Young for providing me with guidance in working with the locomotor activity assay. I appreciate Dr. Glennon's group for the help that they gave me throughout the years. I would like to thank the department of Medicinal Chemistry for offering me this wonderful opportunity to continue my education. On this long journey, my family helped motivate me with their neverending pep talks, love, and support. Thank you Mommy, Daddy, Malita, Shenita, and Wade, I love you all. I would like to give a special thanks to my mother because any decisions that I have made she always stood by me and told me that she was proud of me. I would like to thank my boyfriend Artis for his love, support, and encouragement. I definitely would like to say thank you to my friend Natasha Smith because she always listened to me and gave me good advice. Finally I would like to acknowledge and give thanks to Dr. Dukat, Dr. Glennon, and the School of Pharmacy for financial assistance. Table of Contents Page I . Acknowledgements .............................................................................................................11 . List of Tables .................................................................................................................... vll . List of Figures .................................................................................................................. vlll . List of Schemes ................................................................................................................. xi1 ... List of Abbreviations ....................................................................................................... xm Abstract ............................................................................................................................. xv I. Introduction ........................................................................................................1 11. Background ... .. .... .. .. ... .... ... .. .. .. .... .. .. .... .. .. .. ... .. .. .. .. .. .. .. .. .. .. .4 A. Pain ..........................................................................................................4 B. 5-HT3 Receptors .. .. .. .7 1. Classification ... .. ... ... .. .. ..... .. .. .. .. .... .. .. .. ... .. ... .. ... .. .. .. .. .. .. ..7 2. Structure .. .. .. .. .. .. ... ... ... .. .. .. ... .. .. .. ... ... .. ... .. .. .. .. .. .. .. .. .. .. .. ...9 3. Pharmacology ........................................... ........... ... .. ... ......... ............ 12 4. Ligands and Structure-Activity Relationships (SAR) ....... ............... 14 a) Agonists ........................................................... .... .. ................... ... 14 b) Antagonists ..... ..................................................... .............. ....... ... 19 C. a2-Adrenoceptors................................................................................... 30 1. Classification .................................................................................... 30 2. Structure .. .. .. .. .. .. .. .. .. .. ... .. .. .. .. .. .. .32 3 . Pharmacology ..................................................................................-36 4 . Ligands and SAR ............................... .'. ............................................ $38 a) Agonists ....................................................................................... 38 b) Antagonists ..................................................................................50 c) Therapeutic Applications of a2-Adrenoceptor Agents ...............55 D . Behavioral Tests for Nociception .......................................................... 64 111. Specific Aims and Rationale ............................................................................ 68 IV . Results and Discussion ....................................................................................76 A . Synthesis ................................................................................................76 a) N-(3-Chloropheny1)guanidine Nitrate (MD-354; 21) ......................76 b) Carbarnate analog of MD-354, 113.................................................. 77 c) N-(3-Methoxypheny1)guanidine Nitrate (26) ...................................81 d) A conformationally-constrained analog of MD-354, 114................ 82 B . Behavioral Studies .................................................................................86 1. Results .............................................................................................36 1 .1. MD-354 (21) ............................................................................. 86 1.1.1. Hot-plate assay ............................................................. 86 1 .l.2. Combination studies ..................................................... 88 1.l. 3. MorphineIMD-354 combination studies ......................89 1.2. N-(3,4, 5-Trichloropheny1)guanidine (29) ................................ 91 1.2.1. Tail-flick and hot-plate assays ......................................91 1.2.2. Combination studies .......'.. ............................................ 93 1.2.3. Mechanistic studies ...................................................... 95 1.2.4. Spontaneous activity .................................................102 1.3. The carbamate analog of MD-354, 113 .................................. 103 1.3.1. Tail-flick assay ........................................................... 103 1.3.2. Combination studies ...................................................105 1.4. N-(3-Methoxypheny1)guanidine (26) ..................................... 106 1.4.1. Tail-flick assay .......................................................... 106 1.4.2. Combination studies ...................................................107 2 . Discussion ...................................................................................... 109 V . Conclusions ....................................................................................................122 VI . Experimental ..................................................................................................124 A . Synthesis ..............................................................................................124 1. N-(3-Ch1orophenyl)guanidine Nitrate (MD-354) (21) .........................124 2 . N-(3-Methoxypheny1)guanidine Nitrate (26) ....................................... 125 3 . Methyl N-(3-chlorophenyl)guanidinecarboxylate Hydrochloride (113) .....................................................................................................125 4 . 2-Amino-5-chloro-3, 4-dihydroquinazoline Hydrobromide (114) ........ 126 5 . Dimethyl N,N'~(3~chlorophenyl)guanidinedicarboxylate(1 16) ..........127 6 . 2-Chloro-6-nitrobenzylbromide (1 19) ...................................................127 7 . 2-Chloro-6-nitrobenzylphthalimide (120) ............................................ 128 8 . 2-Chloro-6-nitrobenzylamine (121) ..................................................... 128 9 . 2-Amino-6-chlorobenzylamine (122) ...................................................128 B . Behavioral studies ................................................................................129 1 . Animals ................................................................................................129 2 . Drugs ...................................................................................................-130 3 . Behavioral assays .................................................................................130 a) Hot-plate assay ...............................................................................130 b) Tail-flick assay ...............................................................................131 c) Spontaneous activity ......................................................................132 d) Statistical analysis