Determination of eumelanin in human urine.
Normal and malignant melanocytes produce melanins and melanin-related metabolites, most of which are retained in the cells but some are secreted into the blood and then excreted in the urine. In this study, we developed a method to measure levels of eumelanin in urine samples and evaluated its clinical significance in comparison with the melanin-related metabolites 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI2C) and 5-S-cysteinyldopa (5-S-CD), and with pheomelanin, measured after degradation as 4-amino-3-hydroxyphenylalanine (4-AHP). The method is based on the production of pyrrole-2,3,5-tricarboxylic acid (PTCA) on permanganate oxidation of eumelanin, followed by quantification by liquid chromatography. For 118 urine samples from 10 control subjects, mean urinary excretions of PTCA, 6H5MI2C, 5-S-CD and 4-AHP were 19, 67, 37 and 59 micromol/mol creatinine respectively. In melanoma patients (n = 45), the mean urinary excretions of PTCA, 6H5MI2C, 5-S-CD, and 4-AHP were 91, 926, 4070 and 3530 micromol/mol creatinine respectively. Median level of PTCA in melanoma patients was elevated 2.1-fold compared with control subjects. The degrees of elevation for 6H5MI2C, 5-S-CD, and 4-AHP were 1.8-, 22- and 6.2-fold respectively. Thus, although urinary PTCA is of little clinical value in following the progression of melanoma, urinary 4-AHP appears to be of considerable value in this respect.
Wakamatsu
Kazumasa
K
Department of Chemistry, Fujita Health University School of Health Sciences, Toyoake, Aichi, Japan. kwaka@fujita-hu.ac.jp
Takasaki
Akihiko
A
Kågedal
Bertil
B
Kageshita
Toshiro
T
Ito
Shosuke
S
D000328:Adult; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008297:Male; D008543:Melanins / Q000652:urine*; D008545:Melanoma / Q000473:pathology / Q000652:urine*; D008875:Middle Aged; D011237:Predictive Value of Tests; D012878:Skin Neoplasms / Q000473:pathology / Q000652:urine*
D008543:Melanins; C018362:pheomelanin; C041877:eumelanin