On the Chemical Nature of Urinary Melanogens

Abstract

Malignant melanomas are tumours in which one metabolic pathway — such as that used for the formation of a pigment — is conspicuously accentuated in comparison with normal homologous tissues. This accentuation has been investigated by many authors who studied mainly the relation to the final product — melanin — and to the main catalyst of its formation — tyrosinase. However, it is surprising that little attention has been devoted to the actual course of the reaction and to the formation of the intermediates in vivo. Almost all the existing conclusions in this direction were in fact based only on analogies with model reactions in vitro. Nevertheless, already in the past century the socalled melanogens — precursors of melanin — or their metabolites were described in the malignant melanoma in urine ¹). There is no doubt that the elucidation of the chemical structure, biogenesis and metabolism of these compounds can contribute substantially to the more detailed knowledge of melanogenesis in vivo and thus to a better knowledge of the biochemistry of malignant melanoma in general.