Possible participation of catecholic metabolites known to be present in various regions of the brain that may be incorporated into neuromelanin [7,8]. In addition to dopamine (DA) and norepinephrine (NE) and the corresponding Cys-derivatives, these other metabolites are also thought to be incorporated into neuromelanin [9,10]. substantia nigra, SN; locus coeruleus, LC; 3,4-dihydroxyphenylethanol, DOPE; 3,4-dihydroxyphenylethylene glycol, DOPEG; 3,4-dihydroxyphenylacetic acid, DOPAC; 3,4-dihydroxyphenylmandelic acid, DOMA; 3,4-dihydroxyphenylalanine, DOPA; cysteine, cys. The (O) represents the oxidants. Adapted from [10] with minor modifications.