Presence of methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolines, derivatives of the neurotoxin isoquinoline, in parkinsonian lumbar CSF.

The TIQ derivatives 2-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (2-MDTIQ) and 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (1-MDTIQ, salsolinol) were identified the first time as possible endogenous neurotoxins in parkinsonian but not in normal human lumbar cerebrospinal fluid by high performance liquid chromatography with electrochemical detection. Additionally, MDTIQ analogues were incubated with a monoamine oxidase (MAO) assay. MAO was able to metabolize dose-dependently 2-MDTIQ, whereas 1-MDTIQ was not modified by the enzyme.