Results 191 to 200 of about 5,719 (219)
Some of the next articles are maybe not open access.
Pheomelanin-Based Plumage Coloration Predicts Survival Rates in Birds
Physiological and Biochemical Zoology, 2013Higher vertebrates synthesize two forms of melanin: eumelanin and pheomelanin. While the adaptive functions of eumelanin are diverse, those of pheomelanin, which is phototoxic and whose production consumes a key intracellular antioxidant (glutathione), are not clear apart from being involved in color patterns that confer concealment.
Ismael, Galván, Anders P, Møller
openaire +2 more sources
HPLC Analysis of Pheomelanin Degradation Products in Human Urine
Pigment Cell Research, 2003A 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 +5 more
openaire +2 more sources
PHOTOLYSIS OF PHEOMELANIN PRECURSORS: AN ESR‐SPIN TRAPPING STUDY
Photochemistry and Photobiology, 1986AbstractThe 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 +3 more
openaire +2 more sources
Eumelanins and Pheomelanins: Characterization by Electron Spin Resonance Spectroscopy
Science, 1982Synthetic 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 +4 more
openaire +2 more sources
The pheomelanin chromophore revisited.
2007Pheomelanin photochemistry is commonly regarded as reflecting the behavior of benzothiazine chromophores biogenetically derived from 5-S-cysteinyldopa. This notion, which has become a central dogma in pheomelanin research despite the lack of direct experimental support, has in part been built upon the identification many decades ago in pheomelanin ...
NAPOLITANO, ALESSANDRA +4 more
openaire +2 more sources
Pheomelanin as a Binding Site for Drugs and Chemicals
Pigment Cell Research, 1999Certain drugs and chemicals, such as chloroquine, chlorpromazine, and 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP), are bound to melanin and retained in pigment cells for long periods. This specific retention in pigmented tissues can cause adverse effects in the skin, eye, inner ear, and pigmented nerve cells of the substantia nigra of the brain.
U, Mårs, B S, Larsson
openaire +2 more sources
Synthesis and analysis of pheomelanin degradation products. 2
The Journal of Organic Chemistry, 1984Synthese 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
PHOTOCHEMISTRY OF PHEOMELANIN: ACTION SPECTRUM FOR SUPEROXIDE PRODUCTION
Photochemistry and Photobiology, 1980Abstract— The action spectrum for superoxide production from aerated aqueous solutions of pheomela‐nin was determined by utilizing the nitroblue tetrazolium‐superoxide dismutase assay for superoxide. Superoxide production was greatest in the UVC regions, but continued well into the visible wavelengths. The marked increase in superoxide production noted
Miles R. Chedekel +2 more
openaire +1 more source
Quantitative fluorescence spectra and quantum yield map of synthetic pheomelanin
Biopolymers, 2006AbstractSpectroscopic studies of pheomelanin and its constituents have been sparse. These data present what is by far the most complete description of the fluorescence characteristics of synthetic pheomelanin. Emission spectra between 260 and 600 nm were acquired for excitation wavelengths between 250 and 500 nm at 1‐nm intervals.
openaire +3 more sources
Biosynthetic and structural studies on pheomelanin
Journal of the American Chemical Society, 1982RoseMarie B. Deibel, Miles R. Chedekel
openaire +1 more source