Spectrophotometric characterization of eumelanin and pheomelanin in hair.
Mammalian melanins exist in two chemically distinct forms: the brown to black eumelanins and the yellow to reddish-brown pheomelanins. They can be quantified by HPLC analysis of pyrrole-2,3,5-tricarboxylic acid (PTCA) and aminohydroxyphenylalanine (AHP). We recently developed a spectrophotometric method for assaying the total amount of eu- and pheomelanins by dissolving melanins in Soluene-350 plus water. In this study, we examined whether absorbance at 500 nm (A500) of the Soluene-350 solution reflects the total amount of melanins obtained by the HPLC methods, and whether the ratio of absorbances between 650 and 500 nm reflects the eumelanin/total melanin ratio in mouse hair, sheep wool, and human hair. Our findings were as follows: (1) Total melanin levels calculated from A500 values correlate well with those obtained from PTCA and AHP values by multiplying with the following factors: for mice, PTCA x 45 + AHP x 2.5; for sheep, PTCA x 40 + AHP x 15; and for humans, PTCA x 160 + AHP x 10. (2) The A650/ A500 ratios were higher (0.25-0.33) in black to brown hair while they were significantly lower (0.10-0.14) in yellow to red hair. These results indicate that (1) the A500 value can be used to quantify the total combined amount of eu- and pheomelanins, and (2) the A650/A500 ratio can serve as a parameter to estimate the eumelanin/total melanin ratio. The present method provides a convenient way to qualitatively characterize eu- and pheomelanins in melanins produced in follicular melanocytes.
Ozeki
H
H
Fujita Health University School of Health Sciences, Aichi, Japan.
Ito
S
S
Wakamatsu
K
K
Thody
A J
AJ
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006197:Hair / Q000737:chemistry*; D006801:Humans; D008543:Melanins / Q000032:analysis*; D051379:Mice; D011758:Pyrroles; D012756:Sheep; D013053:Spectrophotometry / Q000379:methods*; D014443:Tyrosine / Q000031:analogs & derivatives
D008543:Melanins; D011758:Pyrroles; C018362:pheomelanin; C041877:eumelanin; D014443:Tyrosine; C071227:4-amino-3-hydroxyphenylalanine; C071226:pyrrole-2,3,5-tricarboxylic acid