Table 1.

Products of chemical degradation and free and protein-bound catechols from pigments isolated from different brain regions

MethodProductPutamenCortexCerebellumSubstantia nigra
H2O2 oxidationPTCA16 ± 324 ± 132 ± 562 ± 13
PDCA<5<5<5106 ± 21
TTCA248 ± 48100 ± 15216 ± 82717 ± 177
TDCA76 ± 339 ± 1278 ± 41449 ± 191
HI hydrolysis4-AHP30 ± 116 ± 438 ± 718 ± 3
4-AHPEA3.6 ± 1.43.9 ± 1.62.8 ± 0.6454 ± 29
Free catecholDOPA2.2 ± 0.62.4 ± 0.62.4 ± 0.45.5 ± 1.2
DA<0.2<0.2<0.26.4 ± 2.7
Cys-DOPA1.5 ± 0.81.3 ± 0.61.3 ± 0.72.8 ± 1.3
Cys-DA<0.5<0.5<0.53.7 ± 1.3
Protein-bound catecholDOPA19 ± 653 ± 1163 ± 9265 ± 20
DA3.4 ± 0.41.2 ± 0.61.2 ± 0.4948 ± 382
Cys-DOPA48 ± 121 ± 228 ± 960 ± 25
Cys-DA<1.0<1.0<1.047 ± 12
  • PTCA and PDCA are typical degradation products from DOPA–melanin and DA–melanin, respectively (13). Both TTCA and TDCA are degradation products from Cys-DOPA–melanin or Cys-DA–melanin. 4-AHP and 4-AHPEA are degradation products from Cys-DOPA–melanin and Cys-DA–melanin, respectively. Values are mean ± SEM (n = 2), each value being obtained in duplicate, and are shown in nanograms per milligram pigment.