Recently, an improved analytical procedure for pheomelanin analysis in pigmented tissues based on alkaline H2O2 degradation has led to the identification, besides BTCA, of a new product, 7-(2-amino-2-carboxy ethyl)-2-carboxy-4-hydroxybenzothiazole (BTCA-2), generated from 2-S-cysteinyldopa (2SCD) derived units. Simultaneous determination of BTCA and BTCA-2 in segments of red hair locks taken at variable distances from the scalp in a group of 19 individuals indicated an abrupt drop of BTCA yields on passing from the root to the tip, whereas BTCA-2 values remained constant throughout hair length. Analysis of 4-amino-3-hydroxyphenylalanine (AHP) and 3-aminotyrosine (AT) showed a closely similar trend, whereas yields of thiazole-2,4,5-tricarboxylic acid (TTCA) increased with increasing distance from the scalp. Prolonged exposure of hair locks to sun light caused a significant decrease in BTCA- but not BTCA-2-yielding elements. Model studies showed a substantial degradation of 5SCD-, but not 2SCD-derived units during pheomelanin synthesis in vitro. It is concluded that red hair pheomelanin consists of a degradable 5SCD-derived bulk component associated to stable 2SCD-derived units. Structural degradation occurs during hair growth probably as a result of oxidative processes related at least in part to sun exposure.
Red Hair Photochemistry: Differential Behaviour of Structural Components to (Photo)degradation / Napolitano, Alessandra; Panzella, Lucia; G., Greco; K., Wakamatsu; S., Ito; D'Ischia, Marco. - STAMPA. - 22:(2009), pp. 661-661. (Intervento presentato al convegno XV Meeting of the European Society for Pigment Cell Research tenutosi a Munster (Germany) nel 20-23/9 2009).
Red Hair Photochemistry: Differential Behaviour of Structural Components to (Photo)degradation.
NAPOLITANO, ALESSANDRA;PANZELLA, LUCIA;D'ISCHIA, MARCO
2009
Abstract
Recently, an improved analytical procedure for pheomelanin analysis in pigmented tissues based on alkaline H2O2 degradation has led to the identification, besides BTCA, of a new product, 7-(2-amino-2-carboxy ethyl)-2-carboxy-4-hydroxybenzothiazole (BTCA-2), generated from 2-S-cysteinyldopa (2SCD) derived units. Simultaneous determination of BTCA and BTCA-2 in segments of red hair locks taken at variable distances from the scalp in a group of 19 individuals indicated an abrupt drop of BTCA yields on passing from the root to the tip, whereas BTCA-2 values remained constant throughout hair length. Analysis of 4-amino-3-hydroxyphenylalanine (AHP) and 3-aminotyrosine (AT) showed a closely similar trend, whereas yields of thiazole-2,4,5-tricarboxylic acid (TTCA) increased with increasing distance from the scalp. Prolonged exposure of hair locks to sun light caused a significant decrease in BTCA- but not BTCA-2-yielding elements. Model studies showed a substantial degradation of 5SCD-, but not 2SCD-derived units during pheomelanin synthesis in vitro. It is concluded that red hair pheomelanin consists of a degradable 5SCD-derived bulk component associated to stable 2SCD-derived units. Structural degradation occurs during hair growth probably as a result of oxidative processes related at least in part to sun exposure.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
