Urinary excretion of 5-S-cysteinyldopa and 6-hydroxy-5-methoxyindole-2-carboxylic acid: differences between pigmented and albino mice.

Urinary excretion of the phaeomelanin precursor 5-S-cysteinyldopa (5-S-CD) and the eumelanin metabolite 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI-2-C) was studied in black and albino mice. The urinary concentration of 5-S-CD was 31.7 ng/ml in black and 16.1 ng/ml in albino mice. The concentration of 6H5MI-2-C was 21.0 ng/ml in the urine of black mice. The compound could not be demonstrated in the urine of albino mice.