Pyrolysis-gas chromatography-mass spectrometry of synthetic neuromelanins

Synthetic neuromelanins obtained from dopamine and/or 5-S-cysteinyldopamine were pyrolyzed at 770 degreesC. The thermal degradation products were separated by gas chromatography and identified by mass spectrometry. Pyrolytic patterns of melanins containing 5-S-cysteinyldopamine-derived component were different from that of dopamine-melanin. Major pyrolytic products of 5-S-cysteinyldopamine-originated units were indentified as 2H-1,4-benzothiazin-5-one, 4-hydroxybenzothiazole and thiazoloisoquinoline and their alkyl derivatives. The results obtained indicate that pyrolysis-gas chromatography-mass spectrometry method is suitable for identification of 5-S-cysteinyldopamine-derived units in synthetic melanin copolymers and it could be applied for structural analysis of natural neuromelanin. (C) 2002 Elsevier Science B.V. All rights reserved.