Results 171 to 180 of about 3,468 (208)
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Analysis and Quantification of Pheomelanins by Radioimmunoassay
Pigment Cell Research, 1988An 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 +3 more
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The “Benzothiazine” Chromophore of Pheomelanins: A Reassessment†
Photochemistry and Photobiology, 2007AbstractThe 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 +3 more
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PHOTOCHEMISTRY OF BENZOTHIAZOLE MODELS OF PHEOMELANIN
Photochemistry and Photobiology, 1984Abstract— 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 +5 more
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PHEOMELANIN PHOTOCHEMISTRY. PHOTOLYSIS OF MODEL COMPOUNDS
Photochemistry and Photobiology, 1982Abstract Two pheomelanin model compounds were prepared and their photochemistries examined. Upon irradiation, an oxygen‐mediated photopolymerization reaction was observed. The photopolymers obtained were characterized by their apparent molecular weights, UV and fluorescence spectra.
C T, Liu, M R, Chedekel
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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
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Pigment Cell and Melanoma Research, 2014 The highest incidence of melanoma in red haired individuals is attributed to the synthesis and phototoxic properties of pheomelanin pigments. Recently, pheomelanin has also been implicated in UV-???independent pathways of oxidative stress; however, the ...
Lucia Panzella +2 more
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UVA, Pheomelanin and the Carcinogenesis of Melanoma
Pigment Cell Research, 2000Cloudman 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
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Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 2013We 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 Galvan +2 more
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Spectroscopy and Photoreactivity of Trichochromes: Molecular Components of Pheomelanins†
Photochemistry and Photobiology, 2006The 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 +6 more
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Pyrolysis-gas chromatography of pheomelanins
Journal of Analytical and Applied Pyrolysis, 1985Abstract 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
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