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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studies on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and analogs

Bucy, Teresa B. 05 September 2009 (has links)
The cyclic allylamine I-methyl-4-phenyl-l ,2,3,6-tetrahydropyridine (MPTP) is a potent and specific neurotoxin that causes a parkinsonian like syndrome in humans and subhuman primates. Research has revealed that MPTP is bioactivated in a reaction catalyzed by flavin containing monoamine oxidase B (MAO B) to yield the dihydropyridinium species MPDP+ which undergoes further oxidation to the ultimate toxin, the I-methyl-4-phenylpyridinium species MPP+. The research summarized in this thesis describes a potential model reaction for the MAO catalyzed conversion of MPTP to MPDP+ and the synthesis and biological evaluation of MPTP analogs bearing a heteroatom at C-4 of the tetrahydropyridine ring. The model for the enzyme catalyzed oxidation of MPTP to MPDP+ is based on the anhydride mediated conversion of MPTP Noxide to MPDP+. This reaction pathway was visualized to mimic a reaction sequence in which an FAD-MPTP adduct cleaves to yield MPDP+ and FADH2. Attempts were made to assess the isotope effect associated with this reaction and to compare that value with the corresponding values for the MAO-B catalyzed reaction [D(V max/Km) = 7-9], the cytochrome P-450 catalyzed reaction [D(V max/Km) = 1.04] and the electrochemical oxidation (D k = 1.35). Unfortunately experimental difficulties prevented a complete analysis of the problem. Specialized equipment will be required to obtain accurate isotope effect measurements. The second study concerns the preparation of the MPTP analogs 4-chloro-, 4-cyano-, and 4-( 4-fluorophenoxy)-1,2,3,6-tetrahydropyridine as potential MAO B substrates that could generate neurotoxic pyridinium metabolites. Results obtained with MAO B have revealed that the dihydropyridinium intermediate formed from 4-( 4-fluorophenoxy)-1 ,2,3, 6-tetrahydropyridine undergoes spontaneous hydrolysis to generate 4-fluorophenol and 1- methyl-4-pyridone. The significance of this finding with respect to neurotoxic mechanisms and design are discussed. / Master of Science

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