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Neuromelanin of the Human Substantia Nigra: A Mixed‐Type Melanin

1994; Wiley; Volume: 62; Issue: 5 Linguagem: Inglês

10.1046/j.1471-4159.1994.62052030.x

1471-4159

Gerd Odh, R Carstam, Jan Paulson, Anna Wittbjer, Evald Rosengren, Hans Rorsman,

Biochemical Analysis and Sensing Techniques

Abstract: Model melanins, synthesized with different cysteinyldopamine/dopamine ratios in the incubates, were oxidized with KMnO 4 and the resulting compounds were analyzed by HPLC. The ratios between a phaeomelanin‐derived compound, thiazole‐4,5‐dicarboxylic acid (TDCA), and a compound derived from eumelanin, pyrrole‐2,3,5‐tricarboxylic acid (PTCA), reflected the composition of the model melanins. The neuromelanin of the human substantia nigra was isolated, and the pigment, as well as intact brain tissue from human substantia nigra was oxidized with KMnO 4 and the TDCA/PTCA ratios were determined. Analysis of the isolated neuromelanin showed it to contain 2.3% sulfur and 8.1% nitrogen. The sulfur content indicates the pigment is a mixed‐type melanin, and the TDCA/PTCA ratio indicates that it consists of units derived from benzothiazines and from indoles in about equal amounts.