Neuromelanins in various regions of human brain are associated with native and oxidized isoprenoid lipids

Neuromelanin (NM) isolated from seven regions of the human brain is found to contain series of natural and oxidized isoprenoid lipids. Specifically, dolichols (dol) and dolichoic acids (dol-CA) with 14-22 and 14-21 isoprene units are identified. Standards of nor-dolichol and nor-dolichoic acid were used to determine the relative amounts of dol and dol-CA compared to the total lipids present in NM for each region. The cerebellum, putamen, globus pallidus, and premotor cortex contained similar amounts of dol, comprising approximately 8–9.5% of the total lipid weight. Interestingly, the corpus callosum contains substantially lower quantities of both dol and dol-CA compared to the other regions—less than 4% dol relative to the total lipid weight. Oxidized and reduced dolichol-related species were identified and determined to be region-dependent.