Results 181 to 190 of about 5,719 (219)

PHOTOCHEMISTRY OF BENZOTHIAZOLE MODELS OF PHEOMELANIN

Photochemistry and Photobiology, 1984
Abstract— The photochemistry of several 4‐hydroxy‐ and 4‐methoxybenzothiazoles has been investigated by laser flash photolysis. In aqueous solutions of pH3–12, the 4‐hydroxybenzothiazole chromophore undergoes monophotonic photoionization to afford e‐aq with quantum yields on the order of 0.06; no evidence for triplet species was obtained.
CHRIS LAMBERT, ROY S. SINCLAIR, T. GEORGE TRUSCOTT, EDWARD J. LAND, R. MILES, CHUNG‐TSING LIU   +5 more
openaire   +1 more source

The “Benzothiazine” Chromophore of Pheomelanins: A Reassessment^†

Photochemistry and Photobiology, 2007
AbstractThe characteristic absorption and photochemical properties of pheomelanins are generally attributed to “benzothiazine” structural units derived biogenetically from 5‐S‐cysteinyldopa. This notion, however, conveys little or no information about the structural chromophores responsible for the photoreactivity of pheomelanins.
NAPOLITANO, ALESSANDRA, DE LUCIA, MARIA, PANZELLA, LUCIA, D'ISCHIA, MARCO   +3 more
openaire   +4 more sources

Pyrolysis-gas chromatography of pheomelanins

Journal of Analytical and Applied Pyrolysis, 1985
Abstract Pheomelanins are the red-brown polymeric pigments found in the skin and hair of red-headed humans and are also responsible for the colour of red feathers and the fur of many animals. Natural pigments were isolated from red hen feathers and red human hair.
Jacek P. Dworzański, Maciej Debowski
openaire   +1 more source

Analysis and Quantification of Pheomelanins by Radioimmunoassay

Pigment Cell Research, 1988
An antiserum against α‐amino‐(4‐hydroxy‐6‐benzothiazolyl)propionic acid (AHBP), a major product obtained after hydriodic acid hydrolysis of pheomelanin, was raised in rabbits immunized with AHBP coupled to bovine serum albumin (BSA). The antiserum was used to develop a radioimmunoassay (RIA) to AHBP. The limit of detection of the RIA is 0.1 ng of AHBP.
A B, Ahene, M R, Chedekel, W H, Koch, W, Maldonado   +3 more
openaire   +2 more sources

Gas chromatography–mass spectrometry analysis of pheomelanin degradation products

Journal of Chromatography A, 2009
Melanoma is most rapidly increasing in the white population and people with pheomelanin skin type are at high risk to develop melanoma. However, little is known about the pheomelanin structure and function, and further elucidation of this melanin is therefore an important task.
Dzeneta, Nezirević Dernroth, Annica, Rundström, Bertil, Kågedal   +2 more
openaire   +2 more sources

UVA, Pheomelanin and the Carcinogenesis of Melanoma

Pigment Cell Research, 2000
Cloudman S91 mouse melanoma cells vary in constitutive and inducible melanin levels. Survival, mutation induction and DNA damage were quantitated after exposure to UVB, UVA and FS20 lamps. Assuming that the observed differences are related to melanin, induced pigment is photo‐protective for survival and mutation after UVB and FS20 exposure, and is ...
HELENE Z. HILL, GEORGE J. HILL
openaire   +1 more source

Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy

Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 2013
We characterize for the first time the vibrational state of natural pheomelanin using Raman spectroscopy and model pigment synthesized from 5-S-cysteinyldopa. The shape of the Raman spectrum was very different from that of eumelanin. Four Raman bands were visible in the 500-2000 cm(-1) wavenumber region about 500, 1150, 1490 and 2000 cm(-1), which we ...
Ismael Galván, Alberto Jorge, Kazumasa Wakamatsu   +2 more
exaly   +3 more sources

Spectroscopy and Photoreactivity of Trichochromes: Molecular Components of Pheomelanins†

Photochemistry and Photobiology, 2006
The trichochromes are a class of small molecules present in pheomelanin (the red melanin) and absent in eumelanin (the black melanin). Herein trichochrome F (TF) and decarboxytrichochrome C (dTC) are examined. Both trichochromes are characterized by a visible absorption band, which is shown to be the result of overlapping transitions of the cis and ...
John D, Simon, Michael R, Goldsmith, Lian, Hong, Valerie R, Kempf, Laura E L, McGuckin, Tong, Ye, Gerard, Zuber   +6 more
openaire   +2 more sources

Artificial pheomelanin nanoparticles and their photo-sensitization properties

Journal of Photochemistry and Photobiology B: Biology, 2016
Pheomelanin-type nanoparticles (PMNPs) were synthesized through a simple oxidative polymerization of 3,4-dihydroxyphenylalanine (DOPA) in the presence of cysteine by KMnO4. The synthesized PMNPs had a diameter of approximately 100nm, exhibited high dispersion stability in neutral water and various culture media and possessed similar morphology to ...
Jung, Pyo, Kuk-Youn, Ju, Jin-Kyu, Lee
exaly   +3 more sources

Ultrathin and Smooth Pheomelanin-like Photoconductive Film

ACS Applied Materials & Interfaces
This study introduces a facile method for the substrate-independent deposition of pheomelanin-like films, revealing unique and promising electrical characteristics. The conventional darkening of a dopamine solution at a basic pH was significantly delayed by the addition of l-cysteine, resulting in a distinctive temporal pattern: an initial quiescent ...
Jeong Sun Lee, Jae Ryeol Jeong, Min Hyung Lee, Kyungtae Kang   +3 more
openaire   +2 more sources