Results 181 to 190 of about 3,468 (208)

Brain size and the expression of pheomelanin‐based colour in birds

Journal of Evolutionary Biology, 2011
AbstractEumelanin and pheomelanin are the most common vertebrate pigments. They generate different colours and are synthesized under different physiological conditions. While pheomelanogenesis requires high levels of a key intracellular antioxidant (glutathione, GSH), eumelanogenesis is inhibited by GSH.
Ismael Galvan, Anders Pape Møller
exaly   +3 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
openaire   +2 more sources

Evidence for Eumelanin and Pheomelanin Producing Genotypes in the Arabian Horse

Journal of Heredity, 1988
The ultrastructural imaging of melanocytes coupled with analyses to detect sulfur-containing melanosomes by energy-dispersive X-ray spectroscopy were used to test the hypothesis that the yellowish-red and black pigments found in Arabian horses result from pheomelanogenesis and eumelanogenesis, respectively.
C M, Woolf, J R, Swafford
openaire   +2 more sources

HPLC Analysis of Pheomelanin Degradation Products in Human Urine

Pigment Cell Research, 2003
A sensitive and specific high performance liquid chromatography (HPLC) method was developed to quantify 4‐amino‐3‐hydroxyphenylalanine (4‐AHP) and 3‐amino‐4‐hydroxyphenylalanine (3‐AHP) in urine. In degradation studies of melanin pigment, 4‐AHP and 3‐AHP are derived from benzothiazine units of pheomelanin and pheomelanin‐related metabolites such as ...
Akihiko, Takasaki, Dzeneta, Nezirević, Kerstin, Arstrand, Kazumasa, Wakamatsu, Shosuke, Ito, Bertil, Kågedal   +5 more
openaire   +2 more sources

Origins of Photodamage in Pheomelanin Constituents: Photochemistry of 4-Hydroxybenzothiazole

The Journal of Physical Chemistry A, 2018
4-Hydroxybenzothiazole (4-HBT) is a molecular constituent of pheomelanin-a polymeric skin centered pigment which acts as a natural photoprotector against harmful solar-UV radiation. Its molecular structure is therefore required to sustain a degree of photostability upon electronic excitation with UV irradiation.
Tolga N. V. Karsili, Barbara Marchetti, Spiridoula Matsika   +2 more
openaire   +2 more sources

PHOTOLYSIS OF PHEOMELANIN PRECURSORS: AN ESR‐SPIN TRAPPING STUDY

Photochemistry and Photobiology, 1986
AbstractThe photolysis of 5‐S‐cysteinyldopa, 2,5‐S,S‐dicysteinyldopa, 4‐hydroxybenzothiazole and cysteinyldopa melanins has been studied by ESR‐spin trapping methods using 5.5‐dimethyl‐1‐pyrroline‐1‐oxide and 2‐methyl‐2‐nitrosopropane as spin traps for hydrated electrons, hydrogen atoms, and carbon‐centered alanyl radicals.
B, Pilas, C C, Felix, T, Sarna, B, Kalyanaraman   +3 more
openaire   +2 more sources

Synthesis and analysis of pheomelanin degradation products. 2

The Journal of Organic Chemistry, 1984
Synthese de 2 des produits de degradation par HI: hydroxy-4 benzothiazolyl-7alanine (A) et hydroxy-3 amino-4 phenylalanine (B). Analyse HPLC des produits de degradation: hydroxy-4 benzothiazolyl-6alanine et son derive methyl-2, amino-3 tyrosine, dihydro-3,4 hydroxy-5 oxo-3 benzothiazine-1,4yl-7alanine, acide amino-7 hydroxy-6 isoquinoleinecarboxylique ...
Dilip G. Patil, Miles R. Chedekel
openaire   +1 more source

High prevalence of cataracts in birds with pheomelanin-based colouration

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2012
The crystalline lens of the eyes of vertebrates focuses light on the retina. Therefore, maintaining the lens clear is necessary for proper visual function. However, oxidative damage to proteins of the lens leads to opacification and lens dysfunction, termed cataract.
Ismael, Galván, Johannes, Erritzøe, Kazumasa, Wakamatsu, Anders P, Møller   +3 more
openaire   +2 more sources

Eumelanins and Pheomelanins: Characterization by Electron Spin Resonance Spectroscopy

Science, 1982
Synthetic dopa melanin and cysteinyldopa melanin have different electron spin resonance spectra. Data are reported for mixtures of these melanins and for dopa-cysteinyldopa copolymers, which are spectroscopically similar. A simple parameterization of the spectra allows estimation of the relative amounts of (i) dopa melanin and cysteinyldopa melanin in ...
R C, Sealy, J S, Hyde, C C, Felix, I A, Menon, G, Prota   +4 more
openaire   +2 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