Olander K, Larsson B, Dencker L
Acta Pharmacol Toxicol (Copenh). 1983 Feb;52(2):135-42. doi: 10.1111/j.1600-0773.1983.tb03415.x.
Melanotic melanomas show a high rate of melanin synthesis. Foreign substances that are accepted as precursors in the formation of melanin may therefore be useful in the diagnosis and therapy of malignant melanotic melanomas, if labelled with suitable radionuclides. We have earlier reported that 2-thiouracil is incorporated in melanotic melanomas, apparently as a false melanin precursor. In the present study it is shown that methimazole and 5-iodo-2-thiouracil are as well accepted as melanin precursors. 5-Iodo-2-thiouracil is of special interest, since iodine has many clinically useful radioisotopes. The chemical properties that characterize substances which are incorporated as false precursors into melanin are discussed. A free sulfur ligand of the thioamides (2-thiouracil, 5-iodo-2-thiouracil, methimazole and thiourea are all incorporated into melanin) seems to be essential and the link between these substances and the melanin. Uracil (which lacks sulfur) and 2-benzylthiouracil (where the sulfur is blocked with a benzyl group) do not attach to melanin. Our conclusion therefore is that the thioureylene structure is the smallest common molecular fragment of the false melanin precursors.
黑色素性黑色素瘤显示出较高的黑色素合成率。因此，如果用合适的放射性核素标记，那些被认为是黑色素形成前体的外来物质可能对恶性黑色素性黑色素瘤的诊断和治疗有用。我们之前报道过，2-硫尿嘧啶可被黑色素性黑色素瘤摄取，显然是作为一种假黑色素前体。在本研究中表明，甲巯咪唑和5-碘-2-硫尿嘧啶也同样被作为黑色素前体所接受。5-碘-2-硫尿嘧啶特别受关注，因为碘有许多临床上有用的放射性同位素。讨论了作为假前体掺入黑色素的物质所具有的化学特性。硫代酰胺（2-硫尿嘧啶、5-碘-2-硫尿嘧啶、甲巯咪唑和硫脲都能掺入黑色素）的游离硫配体似乎是必不可少的，以及这些物质与黑色素之间的联系。尿嘧啶（不含硫）和2-苄基硫尿嘧啶（其中硫被苄基阻断）不与黑色素结合。因此我们的结论是，硫脲烯结构是假黑色素前体的最小共同分子片段。
