title: Interactions of the 1-methyl-4-phenyl-2,3-dihydropyridinium species with synthetic dopamine-melanin.
abstract: This paper describes interactions between the 1-methyl-4-phenyl-2,3-dihydropyridinium (MPDP+) metabolite of the nigrostriatal toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) with synthetic dopamine-melanin, a polymeric pigment which is similar to the neuromelanin found in the nigrostriatal cell bodies of humans and primates. Although MPTP and its 1-methyl-4-phenylpyridinium (MPP+) metabolite bind to the synthetic pigment at physiological pH, both compounds are recovered quantitatively upon treatment with acid. Unlike MPTP and MPP+, MPDP+ proved to be unstable in the presence of synthetic dopamine-melanin which promoted its conversion to the fully oxidized pyridinium product MPP+. The possible biological significance of this interaction is discussed.
mesh_terms: D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D004298:Dopamine / Q000378:metabolism*; D008543:Melanins / Q000378:metabolism*; D010084:Oxidation-Reduction; D011725:Pyridines / Q000378:metabolism; D011726:Pyridinium Compounds / Q000378:metabolism*
chemical_list: D008543:Melanins; D011725:Pyridines; D011726:Pyridinium Compounds; C014121:neuromelanin; C044755:1-methyl-4-phenyl-2,3-dihydropyridinium; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D004298:Dopamine