Biomimetic oxidation of the pheomelanin precursor-5-S-cysteinyldopa in the presence of Zn(2+); ions led to the, isolation of two isomeric products, one of which could be identified as the benzothiazolythiazinodihydroisoquinoline 5, while the other proved too unstable for a complete characterization. Both these products were converted into more stable oxidized forms, which after ethylchloroformate derivatization, were characterized as the ethyl ester/ethoxycarbonyl isoquino. lines 8 and 9. Compound. 5 exhibited,absorption characteristics,similar to those of red hair pheomelanin, including a main band around 400 tun in acids Similarly to red hair pheomelanin and synthetic pigments, 5 afforded on chemical degradation a thiazolylpridinecarboxylic add fragment Model chemical studies allowed the proposal of a formation mechanisin for the benzothiazole and dihydroisoquinoline systems in compound 5.
Uncovering the structure of human red hair pheomelanin: benzothiazolylthiazinodihydroisoquinolines as key building blocks / G. Greco, L. Panzella, L. Verotta, M. d'Ischia, A. Napolitano. - In: JOURNAL OF NATURAL PRODUCTS. - ISSN 0163-3864. - 74:4(2011), pp. 675-682.
Uncovering the structure of human red hair pheomelanin: benzothiazolylthiazinodihydroisoquinolines as key building blocks
L. Verotta;
2011
Abstract
Biomimetic oxidation of the pheomelanin precursor-5-S-cysteinyldopa in the presence of Zn(2+); ions led to the, isolation of two isomeric products, one of which could be identified as the benzothiazolythiazinodihydroisoquinoline 5, while the other proved too unstable for a complete characterization. Both these products were converted into more stable oxidized forms, which after ethylchloroformate derivatization, were characterized as the ethyl ester/ethoxycarbonyl isoquino. lines 8 and 9. Compound. 5 exhibited,absorption characteristics,similar to those of red hair pheomelanin, including a main band around 400 tun in acids Similarly to red hair pheomelanin and synthetic pigments, 5 afforded on chemical degradation a thiazolylpridinecarboxylic add fragment Model chemical studies allowed the proposal of a formation mechanisin for the benzothiazole and dihydroisoquinoline systems in compound 5.File | Dimensione | Formato | |
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