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Title: | The Synthesis Of 11C-Labelled Melatonin Agonists from 11C-Carbon Dioxide |
Authors: | Schulze, Brita G. |
Advisor: | McCarry, Brian E. |
Department: | Chemistry |
Keywords: | radioisotope, neurohormone melatonin, Positron Emission Tomography |
Publication Date: | Apr-1994 |
Abstract: | This thesis describes the application of the radioisotope 11C to the synthesis of two analogues of the neurohormone melatonin. The labelled compounds were intended to be used as tracers for the medical imaging technology Positron Emission Tomography (PET). [ 11C]Carbon dioxide, produced in a small on-site cyclotron by the nuclear reaction 14N(p,a)11C, was converted into [11C]CH3COC1 by reaction first with CH3MgBr, followed by reaction with phthaloyl dichloride. The labelled acid chloride was distilled into a solution of an amine, yielding the corresponding 11C-labelled amide, which was purified by a simple solid-phase extraction method. An apparatus was designed and built that allowed the remote synthesis with several hundred millicuries of [11C]C02• The apparatus was mounted in a hot cell and operated remotely with a Macintosh Powerbook programmed in Hypercard. The apparatus and software are generic for these acylation reactions. The individual reaction steps were optimized in terms of reaction time, solvents and equipment; radiosyntheses of a number of purified labelled acetamides were completed in 35 minutes. The radiochemical yields ranged from 15 to 20% with specific activities in the 500 mCi/J..tmol range at the end of the synthesis. 2-Iodo-[11C-acetyl]melatonin (11) and 7-methoxynaphthylenyl-1-ethyl-N-[11Cacetyl] acetamide (15) were synthesized for the first time for PET studies. It was shown that both compounds readily cross the blood-brain-barrier and penetrate into all brain tissues. Specific binding to the melatonin receptors in the suprachiasmatic nuclei of the hypothalamus could not be visualized with either one of the 11C-labelled ligands because of low specific activity and high nonspecific binding. |
URI: | http://hdl.handle.net/11375/22643 |
Appears in Collections: | Digitized Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Schulze_Brita_G_1994April_Masters.pdf | 4 MB | Adobe PDF | View/Open |
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