melanin

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melanin

 [mel´ah-nin]
any of several closely related dark, sulfur-containing pigments normally found in the hair, skin, ciliary body, choroid of the eye, pigment layer of the retina, and certain nerve cells. They occur abnormally in the tumors known as melanomas and may be excreted in the urine when such tumors are present (melanuria).

mel·a·nin

(mel'ă-nin),
Any of the dark brown to black polymers of indole-5,6-quinone and/or 5,6-dihydroxyindole 2-carboxylic acid that normally occur in the skin, hair, pigmented coat of the retina, and inconstantly in the medulla and zona reticularis of the adrenal gland. Melanin may be formed in vitro or biologically by oxidation of l-tyrosine or l-tryptophan, the usual mechanism being the enzymatic oxidation of l-tyrosine to 3,4-dihydroxy-l-phenylalanine (dopa) and dopaquinone by monophenol monooxygenase, and the further oxidation (probably spontaneous) of this intermediate to melanin. Compare: eumelanin, pheomelanin.
Synonym(s): melanotic pigment
[G. melas (melan-), black]

melanin

/mel·a·nin/ (mel´ah-nin) any of several closely related dark pigments of the skin, hair, choroid coat of the eye, substantia nigra, and various tumors, produced by polymerization of oxidation products of tyrosine and dihydroxyphenol compounds.

melanin

(mĕl′ə-nĭn)
n.
Any of a group of naturally occurring dark pigments, especially the pigment found in skin, hair, fur, and feathers.

melanin

[mel′ənin]
Etymology: Gk, melas, black
a black or dark brown pigment that occurs naturally in the hair, skin, and iris and choroid of the eye. See also melanocyte.

melanin

A dark natural pigment found in the epidermis or skin adnexal structures. It is a complex polymer of oxidised tyrosine synthesised from DOPA and dopaquinone in response to actinic stimulation and bound to a carrier protein by melanocytes—in the skin, mucous membrane, pia arachnoid, retina, inner ear and mesentery. Melanin is detected in tissue sections by the Fontana-Masson stain.

melanin

 Physiology A dark natural body pigment found in the epidermis or skin adnexal structures. See Albinism, DOPA, Melanoma.

mel·a·nin

(mel'ă-nin)
Any of the dark brown to black pigments that occur in the skin, hair, pigmented coat of the retina, and medulla and zona reticularis of the suprarenal gland.
[G. melas (melan-), black]

melanin

The body's natural colouring (pigment) found in the skin, hair, eyes, inner ears and other parts. In body cells, melanin is bound to protein. It is a complex POLYMER formed from the amino acid TYROSINE (4-hydroxphenylalanine) by oxidation via dopa and dopaquinone.

melanin

a dark brown or black pigment found in skin or hair and in the iris and choroid layer of the EYE. Melanin is found in special cells called MELANOPHORES. See ALBINISM, DOPA.

Melanin

A dark insoluble pigment found in humans in the skin, hair, choroid layer of the eye, and a part of the brain called the substantia nigra.

melanin

dark brown/black pigment within melanosomes of epidermal melanocytes (see melanosome)

melanin (meˑ·l·nin),

n a substance produced by melanocytes found in the deepest layer of the epidermis; protects the skin from the effects of the sun's harmful rays. Variations in skin color are a result of the level of melanin produced by each individual.

melanin

Dark brown to black pigment normally present in the skin, the hair, the choroid, the iris, the retina, the ciliary body, the cardiac tissue, the pia mater and the substantia nigra of the brain. It is absent in albinos. See albinism; fuscin; melanocyte; melanosis; choroidal naevus; retinal pigment epithelium.

mel·a·nin

(mel'ă-nin)
Any of the dark brown to black pigments that occur in the skin, hair, pigmented coat of the retina, and medulla and zona reticularis of the suprarenal gland.
[G. melas (melan-), black]

melanin (mel´ənin),

n the dark amorphous pigment of melanotic tumors, skin, oral mucosa, hair, choroid coat of the eye, and substantia nigra of the brain.

melanin

a dark, sulfur-containing pigment normally found in the hair, skin, ciliary body, choroid of the eye, pigment layer of the retina, and certain nerve cells. It occurs abnormally in certain tumors, known as melanomas, and is sometimes excreted in the urine when such tumors are present (melanuria).

melanin deficiency
hypopigmentation, leukoderma, hypomelanosis.
excess melanin
hyperpigmentation, hypermelanosis, melanism, melanoderma, melanotrichia.
melanin-stimulating hormone
see melanocyte-stimulating hormone.
References in periodicals archive ?
According to the researchers, 32% of the species studied have complex plumage patterns, with the vast majority of these complex patterns produced by melanins rather than carotenoids.
The exact numbers depend on the configuration, but as an example, we can power a 5 milliWatt device for up to 18 hours using 600 milligrams of active melanin material as a cathode.
In the pronota the patterns are made up entirely of melanin laid over a white background.
Therefore, in this study, the direct influence of salidroside on tyrosinase activity and melanin synthesis was investigated to testify if this compound has the skin lightening effect to be developed as a product for cosmetic industry and skin pigmentation disorder treatment.
Samples were prepared by dissolving the different melanins in a 0,1 M sodium carbonate buffer (pH 10,3) obtaining a concentration of 0,03 g/L.
2004) found that no melanocytes can also cause the whitening of human hair due to the lack of melanins in the hair shaft.
Researchers could now look for melanin, ubiquitous in the animal kingdom, in a wide range of fossils, including ichthyosaurs, dinosaurs, insects, mollusk shells and mammals.
According to Alban Muller, the sun oxidizes the tyrosine furnished by the product to form melanin on the skin.
The binding of certain drugs and inorganic cations to melanin has been studied extensively both in vitro and in vivo by Larsson and co-workers (7-9).
In a previous study, it has been shown that naringenin increases the melanin content and tyrosinase activity by increasing the expression of melanogenic enzymes (Ohguchi et al.
Chemists are now trying to determine what melanin actually does in the skin.
Remarkably melanins that have been extensively alkali/acid-treated or extracted by acid hydrolysis still maintain their immunogenic properties (Zeise, 1995; Sava et al.