Eumelanin (precursor) metabolites as markers for pigmented malignant melanoma: a preliminary report

The pigmented form of malignant melanoma is a tumor with an exceptionally high production of melanin. It is therefore comprehensible that the precursors of melanin and/or their metabolites are excreted in elevated amounts during the course of this disease. Using gas chromatography--mass spectrometry we were able to identify five indolic compounds in the urine of melanoma patients: 5,6-dihydroxyindole (5,6DHI), 5-hydroxy-6-methoxyindole (5H6MI), 6-hydroxy-5-methoxyindole (6H5MI), and 5-hydroxy-6-methoxyindolyl-2-carboxylic (5H6MI2C) and 6-hydroxy-5-methoxyindolyl-2-carboxylic acids (6H5MI2C). For their quantitative mass fragmentographic analyses, deuterium-labeled analogs have been synthesized. The first experience with these measurements is presented.