Odh G, Hindemith A, Carstam R, Paulson J, Rosengren E, Rorsman H
Department of Pharmacology, University of Lund, Sweden.
Pigment Cell Res. 1994 Dec;7(6):419-27. doi: 10.1111/j.1600-0749.1994.tb00071.x.
Information on the composition of melanins is obtained by analysis both of 4-amino-3-hydroxyphenylalanine (AHP) after hydriodic acid degradation and of pyrrole-2,3,5-tricarboxylic acid (PTCA) after potassium permanganate oxidation. Analysis of thiazole-4,5-dicarboxylic acid (TDCA) and pyrrole-2,3-dicarboxylic acid (PDCA) after permanganate oxidation, provides additional information on the composition, TDCA on pheomelanin residues, and PDCA on indolic residues without carboxy groups. Using model melanins formed from dopa and cysteinyldopa in different proportions, we found the TDCA/(PTCA+PDCA) ratio to yield a reliable estimate of the relative proportions of pheomelanin and eumelanin. The PDCA/PTCA ratio reflects the relationship between indole residues with and without carboxy groups. We have analyzed degradation products from cultures of IGR 1, an extensively studied melanoma cell line. Cell cultures were harvested after 2, 4, and 7 days. Culture media were changed after 2 days in all series, and also after 4 days in one series harvested at 7 days. Cells without medium change had seven times the amount of melanin found in cultures with medium change. The PDCA/PTCA ratio decreased with increasing amounts of melanin. With increased melanization, eumelanin is increased relatively more than pheomelanin. The cell content of 5-S-cysteinyldopa (5-S-CD) was similar in all cultures, while 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MICA), a eumelanin precursor metabolite, was found in increased amounts of media of heavily pigmented cultures.
通过对氢碘酸降解后的4-氨基-3-羟基苯丙氨酸（AHP）以及高锰酸钾氧化后的吡咯-2,3,5-三羧酸（PTCA）进行分析，可获取黑色素的组成信息。对高锰酸钾氧化后的噻唑-4,5-二羧酸（TDCA）和吡咯-2,3-二羧酸（PDCA）进行分析，可提供有关组成的更多信息，TDCA用于分析褐黑素残基，PDCA用于分析无羧基的吲哚残基。使用由不同比例的多巴和半胱氨酰多巴形成的模型黑色素，我们发现TDCA/（PTCA + PDCA）比率能够可靠地估计褐黑素和真黑素的相对比例。PDCA/PTCA比率反映了有羧基和无羧基吲哚残基之间的关系。我们分析了广泛研究的黑色素瘤细胞系IGR 1培养物的降解产物。在2天、4天和7天后收获细胞培养物。所有系列在2天后更换培养基，在7天收获的一个系列中4天后也更换培养基。未更换培养基的细胞中的黑色素含量是更换培养基的培养物中的7倍。PDCA/PTCA比率随着黑色素含量的增加而降低。随着黑色素化程度的增加，真黑素的增加相对多于褐黑素。所有培养物中5-S-半胱氨酰多巴（5-S-CD）的细胞含量相似，而在色素沉着严重的培养物的培养基中发现了真黑素前体代谢物6-羟基-5-甲氧基吲哚-2-羧酸（6H5MICA）的含量增加。
