Synthesis and Pharmacological Studies on Some 2–Hydroxy Haloalkylamines As H2 Antagonist
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Π Synthesis and pharmacological studies on some 2–hydroxy haloalkylamines as H2 antagonist A thesis submitted in fulfillment of the Requirement of the University of Khartoum. For: Master Degree of Pharmacy (M. Pharm.) To: DEPARTMENT OF PHARMACOLOGY FACULTY OF PHARMACY UNIVERSITY OF KHARTOUM By: Amna Elhassan Hamad (B. Pharm., U. of K.) Supervisor: Prof. Abdallah Awad Abdallah Co – Supervisor: Dr. Osama Yousif Mohamed December 2003 This work is dedicated to: My parents, brothers and sisters, for their support and supreme encouragement To my family: Engineer Mohammed I. Hamad, for his encouragement and motivation To my kids and daughters: Ahmed, Abubakr, Omer, Osama, Huda and Nuha. For their infinite patience & endurance during all time I spend away from them. ACKNOWLEDGEMENT Initially I solely thank Almighty Allah for accomplishing this work. I would like to express my thanks and gratitude to my supervisor Dr. Abdalla Awad Abdalla, former Professor of Medicinal Chemistry (CTS) for his courtesy and careful supervision and for his continuous guidance. My sincere thanks and gratitude to my Co–Supervisor, Associated Professor Osama Yousif Mohammed, Department of Pharmacology (U. of K.) for his valuable advises throughout all stages of the study. Special thanks and gratitude to Dr. Abdel Wahab Hassan Mohammed, Head Department of Pharmacology, Medicinal and Aromatic Plants Institute National Center for Research, for his valuable advises and helps. And my appreciation and thanks giving to all staff members of Medicinal and Aromatic Plants Institute, especially Reem Hassan Ahmed (B. V. & MSc. V, U. of K.). Thanks to all staff members of Pharmacology and Pharmaceutical Chemistry Departments, Faculty of Pharmacy, U. of K. for their co– operation. My greatest and deepest gratitude to Ali Hassan Hamad B. Sc., U. of K., for his intangible support and encouragement. LIST OF CONTENTS Subjects Page List of Contents: ………………………………………………….. I List of Tables: …………………………………………………….. IV List of Schemes: …………………………………………………… IV List of Figures: ………………………………………………….. V Abstract in Arabic: ………………………………………………. VI Abstract in English: ……………………………………………… VII MEDICINAL CHEMISTRY CHAPTER ONE: INTRODUCTION 1.1 Histamine and anti–histaminic drugs: …….…………………… 1 1.1.1 Histamine: ………………………..……………….….. 1 1.1.1.1 Histamine releasing substances: …………… 2 1.1.1.2 Anti–histamines: …………………………… 3 1.2 Pharmacology: ………………………………….……………. 3 1.3 Chemistry: …………………………..…………….…….….…. 5 1.3.1 Salt formation: ………………………………….…….. 5 1.3.2 Structure–activity relationships (SAR): ……....………. 5 1.4 Ethanolamine derivatives: ……………….……………………. 7 1.5 Ethylene diamine derivatives: ………………………………..... 9 1.6 Propylamine derivatives: …………………………………….... 12 1.7 Testing of antihistamines: ………………………………….….. 14 1.8 Gastric secretion: ………………………………………….…… 14 1.9 Cardiovascular effect of histamine: ……………………....…… 14 1.10 Histamine receptors: ……………………………………….…... 15 1.11 Histamine agonist: ……………………………………….……..16 1.12 Histamine antagonist: ………………………………………..... 16 1.13 Aim of the project: …………………………………………….. 18 CHAPTER TWO EXPERIMENTAL 2.1 Apparatus and materials: ………………………………………. 21 2.2 Methods: ……………………………………………………..…23 2.2.1 Preparation of the 2–(N,N dibenzylamino)–I–P– haloaryl–I– hydroxy–ethanes: ………………………………………23 2.2.1.1 Preparation of the bromoacetophenones from the acetophenones: ………………………………23 2.2.1.2 The preparation of the bromohydrins from the bromoacetophenone: …………..………..….. 26 2.2.1.3 Preparation of the 1–hydroxy–I–aryl–2–(N,N–diben– zyl amino) ethane: …………………………. 29 2.2.1.4 The preparation of 1–hydroxy–I–aryl–2–(N,N–diben– zylamino) ethanes hydrochloride salts: ….….. 32 2.2.2 Experimental discussion: ……………..……………….. 34 2.2.2.1 Bromination: ……………………………...… 34 2.2.2.2 Reduction: ………………………………….. 37 2.2.2.3 Coupling of bromohydrin with dibenzylamine 38 CHAPTER THREE DISCUSSION 3.1 Receptors: ……………………………………………..………..40 3.2 Agonist: ……………………………………………..…………. 41 3.3 Antagonist: …………………………………………….………. 41 3.4 Ligands: …….……………………………….…………..……...41 PHARMACOLOGY CHAPTER FOUR: INTRODUCTION 4.1 Histamine: ………………………...…….…….…………..…… 53 4.1.1 Histamine synthesis: ……………………………….….. 53 4.1.2 Histamine storage and release: ………….…………….. 54 4.1.3 Histamine metabolism: ……………………………….. 55 4.1.4 Histamine receptors: …………………………………... 56 4.1.5 Chemical structure of histamine and its agonist: ……… 57 4.1.6 Chemical structure of histamine antagonist: ………….. 57 4.1.7 Structure activity relationship of histamine agonist and antagonist: …………………………………………….. 58 4.2 Peptic ulcer: ……………………………………………………. 60 4.2.1 Peptic ulcer prevalence: ……………………………….. 60 4.2.2 Types of peptic ulcer: ………..…………………….…. 61 4.2.3 Peptic ulcer etiology: ………………………………….. 62 4.2.4 Ulcer treatment: ……………………………………….. 64 4.2.4.1 Surgical treatment: ……………….…………. 65 4.2.4.2 Medical treatment (Medicines): …………….. 65 4.2.4.2.1 Antacids: ……………………..…………. 66 4.2.4.2.2 Sucralfate: ……………………………….. 67 4.2.4.2.3 Bismuth chelate: ……..……………….…. 67 4.2.4.2.4 Prostaglandin analog: Misoprostol: …….. 67 4.2.4.2.5 Histamine H2 receptors antagonists e.g. cimetidi– ne, ranitidine and famotidine: ………..….. 68 4.2.4.2.6 Proton pump inhibitors: ……………….... 69 4.2.4.2.7 Treatment of H pylori infection efficacy: .. 69 4.2.5 Efficacy: ………………………………………………. 70 4.2.6 Side effects: ………………………..…………………. 70 4.2.7 Drug–drug interaction: ………..……………………… 71 4.2.8 Rationale: ………………………………………………72 CHAPTER FIVE: EXPERIMENTAL 5.1 Chemicals and their sources: ………………………………….. 73 5.2 Equipments and instruments: ………………………………….. 73 5.3 Animals: ……………………………………………………….. 74 5.4 Methods: ………………………………………………………..74 5.4.1 Contracting rat uterus: ……………………………….. 74 5.4.2 Evaluation of antiulcerogenic activity using experimentally induced ulcer in rat stomach and duodenum: …………. 75 5.4.3 Guinea pig ileum preparation: ……..………..………… 76 5.4.4 Guinea pig atrium preparation: ……………..……..…... 77 5.4.5 The principle of pA2 system: ………………..…..…….. 78 5.4.6 Determination of pA2 value of cimetidine P–chlor, and P– bromoalkyl–amine acting on rat uterus: ………………. 79 5.4.7 Determination of pA2 value of mepyramine 2–chloralkylamine and 2–bromoalkylamine acting on guinea pig ileum: … 79 5.5 Materials (Preparation of test solution and blank): ……………. 80 CHAPTER SIX: RESULTS & DISCUSSION 6.1 The antiulcerogenic activity of 2–chloroalkylamine, 2–bromoa lkyl– amine and cimetidine on experimentally aspirin–induced ulcers in rat: …………………………………………………………... 81 6.2 Effect on guinea pig atria: ……………………………………... 82 6.3 Effect on the contracting rat uterus: ……………………..…….. 82 6.4 Effect on isolated guinea pig ileum: ………………………....... 83 6.5 Median inhibitory concentration (IC50) of cimetidine, 2–chloro and 2– bromo–alkylamine on aspirin induced ulcer in rat (n = 5): ..…. 83 6.6 pA2 values for cimetidine, 2–chloro and 2–bromoalkylamine versus histamine acting on rat uterus: …….…………………………... 83 6.7 pA2 values for mepyramine, 2–chloro, and 2–bromoalkylamine versus histamine acting on guinea pig ileum: …………………………. 84 6.8 Results Discussion: …..……………………………..…………. 97 CHAPTER SEVEN : SUMMARY AND CONCLUSION: ……… 101 CHAPTER EIGHT: SUGGESTION FOR FUTURE WORK: …. 102 REFERENCES: ………………………………………………………………. 103 LIST OF TABLES Tables Title Page Tab. 1 Starting materials and specifications: ………..………………… 22 Tab. 2 Chemical nomenclature of the compounds synthesized: ……… 22 Tab. 3 Bromoacetophenones: ……………………..…………………... 25 Tab. 4 Bromohydrins: ……………………………..………………….. 28 Tab. 5 Aminoalcohols liquids: ……………..…………………………. 31 Tab. 6 Aminoalcohol Hcl salts: ……………..………………………… 33 Tab. 7 Effect of 2–chloro alkylamine on aspirin–induced ulcer in rat: .. 85 Tab. 8 Effect of 2–bromoalkylamine on asprinin–induced ulcer in rat: . 85 Tab. 9 Effect of cimetidine on asprinin–induced ulcer in rat: ………… 86 Tab. 10 The value of pA2 of cimetidine, P–chlor, and P–bromoalkylamine versus histamine acting on rat uterus: ……….………………… 86 Tab. 11 The value of pA2 of mepyramine, P–chloro and P–bromo alkylamine Versus histamine acting on guinea pig ileum: ………………… 87 Tab. 12 Median inhibitory concentration (IC50) of cimetidine, 2–chloroalky– lamine and 2–bromoalkylamine on aspirin–induced ulcer in the rat (n = 6): …………………………………………………………. 87 LIST OF SCHEMES Scheme No. Title of Scheme PAGE Scheme 1 General scheme for the preparation of intermediates and the amino–hydroxy ethanes: ……………………………. 20 LIST OF FIGURES Fig.No. Figures Title Page Fig. 1 Chemical structure of histamine agonist and antagonist: … 16 Fig. 2 Examples of the structures of the agonists of histamine Receptors: ………………………..……………..…………. 48 Fig. 3 The effect of an ideal competitive antagonist on the dose response curve for an agonist: …………….……………..…………. 49 Fig. 4 An outline of the mode of action of a competitive antagonist (6) with an antagonist: …………….………..………………… 50 Fig. 5 The effect of a non–competitive antagonist on the dose–response curve of agonist: ……………..………………..……………….. 51 Fig. 6 The effect of an ideal antagonist on the response of a receptor: …………………………………………………... 52 Fig. 7 (a) No desensitization (b) Desensitization: ……………….. 52 Fig. 8 2–chloroalkylamine versus histamine acting on rat uterus: … 88 Fig. 9 2–bromoalkylamine versus histamine acting on rat uterus: … 89 Fig. 10 2–chloroalkylamine versus histamine acting on guinea pig atrium: …………………………………………………………. 90 Fig. 11 2–bromoalkylamine versus histamine acting on guinea pig atrium: …………………………………………………………. 91 Fig. 12 2–chloroalkylamine versus histamine acting on guinea pig ileum: …………………………………………………………...92 Fig. 13 2–bromoalkylamine versus histamine acting on guinea