Saturday, June 21, 2008

What is Melanin Pigment?

Melanin pigment is important in other areas of the body, such as the eye and the brain, but it is not known what the melanin pigment does in these areas. Melanin pigment is present in the retina (RET-n-ah), and the area of the retina called the fovea (FOE-vee-ah) does not develop correctly if melanin pigment in not present in the retina during development (see below). The other areas of the retina develop normally whether or not melanin pigment is present. The nerve connections between the retina and the brain are also altered if melanin pigment is not present in the retina during development. The iris has melanin pigment and this makes the iris opaque to light (no light goes through an opaque iris).

A composite melanin pigment in the form of particles comprising a spherical core less than 1 μm in diameter, which comprises at least one wax and at least one surfactant, and an outer layer which envelops the core, which comprises at least one compound resulting from the oxidative polymerization of a melanin pigment precursor; and uses of the pigment in powder form or in the form of an aqueous dispersion, in cosmetic compositions, in particular in dye products and/or make-up products and/or care products for keratin substances such as the skin, the hair and the nails.

Melanins are pigments of high molecular weight formed by oxidative polymerization of phenolic or indolic compounds. A number of fungi, including Aspergillus nidulans, produce pigments related or identical to melanin, which are located on cell walls or exist as extracellular polymers. The aim of the present study was to assess the antioxidant activity of synthetic melanin and of the pigment extracted from the mycelium and culture medium after growth of the highly melanized strain (MEL1) from A. nidulans. The ability of the melanin pigment to scavenge the oxidants HOCI and H_2O_2 was evaluated by inhibition of the oxidation of 5-thio-2-nitrobenzoic acid (TNB) using several melanin concentrations.

Melanins have very diverse roles and functions in various organisms. A form of eumelanin makes up the ink used by Cuttlefish as a defence mechanism against predators. Melanins also protect microorganisms, such as bacteria and fungi, against stresses that involve cell damage by solar UV radiation or generation of reactive oxygen species. These include high temperature as well as chemical (e.g. heavy metals and oxidizing agents), and biochemical (e.g., host defenses against invading microbes) stresses. Therefore, in many pathogenic microbes (for example, in Cryptococcus neoformans, a fungus) melanins appear to play important roles in virulence and pathogenicity by protecting the microbe against immune responses of its host.

Melanin Pigment a spreading and frequently recurring cancer of specialized skin cells (melanocytes) that produce the protective skin-darkening pigment melanin. In the United States melanoma represents less than 5 percent of all cases of skin cancer, yet it is responsible for nearly three-quarters of all skin cancer deaths and is increasing in frequency. Unlike other skin growths, melanoma is always malignant.

A composite melanin pigment according to claim 18, wherein said at least one nonionic amphiphilic compound with a long polar head is selected from: polyalkoxylated and polyglycerolated fatty acids and amides, polyalkoxylated and polyglycerolated fatty acid esters of polyols, polyalkoxylated and polyglycerolated alkylphenols and fatty alcohols, polyalkoxylated and polyglycerolated 1,2- and 1,3-alkanediols and -alkenediols, dodecyl thioethers of polyacrylamide, alkoxylated of fatty acids, and fatty alcohols of lanolin, said at least one nonionic amphiphilic compound containing at least 50 polar or hydrophilic units constituting the polar head.

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