Detection of 5-S-cysteinyldopamine in human brain.

5-S-Cysteinyldopamine was synthesized and used as reference compound in HPLC analyses of extracts from various regions of human brain. The compound could be detected in brain regions rich in dopamine (caudate nucleus, putamen, globus pallidus and substantia nigra) but not in other regions (cerebellum, occipital cortex). The occurrence of 5-S-cysteinyldopamine in dopaminergic brain regions supports the hypothesis that dopamine in part undergoes autoxidation, leading to formation of highly reactive quinones. The newly discovered metabolite may prove useful in future studies of dopamine autoxidation and the possibly resultant cytotoxicity in aging and degenerative brain disorders.