Red hair pigments

Proopiomelanocortin (POMC) is the precursor peptide of hormones and neuropeptides expressed in the pituitary and the hypothalamus (adrenocorticotropic hormone (ACTH), lipotropin, a-melanocyte-stimulating hormone (aMSH), yMSH, 3-endorphin, and others). The main clinical consequences of POMC deficiency are adrenal insufficiency (due to absence of ACTH), red hair pigmentation (due to absence of MSH) and severe early-onset obesity (due to the lack of aMSH). 

H. Krude, H. Beiebermann, W. Luck, et al. Severe early-onset obesity, adrenal insufficiency and red hair pigmentation caused by POMC mutations in humans. Nature Genetics 19,155 (1998). 

Pheomelanins are the yellow-red pigments and are lighter in color than the brown-black pigments of human hair. Both pheomelanins and eumelanins occur as granules in melanocytes. Prota and co-workers [14,62] have proposed that red hair pigments are formed by a modihcation of the eume-lanin pathway described earlier. The pheomelanin pathway, however, involves the interaction of cysteine with dopaquinone. Figure 4-28 summarizes Prota s [62] description of a common metabolic pathway for formation of all melanins and shows how pheomelanin formation relates to eumelanin biosynthesis. 

Riley, P.A., Melanogenesis and melanoma, Pigment Cell Res., 16, 548, 2003. Rorsman, H., The pigmented life of a red hair bibliographic review, Pigment Cell Res., 17, 191, 2004. 

Melanin from natural sources falls into two general classes. The first component is pheomelanin (I), which has a yellow-to-reddish brown colour, and is found in red feathers and red hair. The other component is eumelanin (which has two principal components, II and III). Eumelanin is a dark brown-black compound, and is found in skin, hair, eyes, and some internal membranes, and in the feathers of birds and scales of fish. Melanin is particularly conspicuous in the black dermal melanocytes (pigment cells) of dark-skinned peoples and in dark hair and is conspicuous in the freckles, and moles of people with lighter skins. 

Napolitano, A. Di Donato, R Prota, G. Zinc-Catalyzed Oxidation of 5-S-Cystei-nyldopa to 2,2 -Bi(2H-l,4-benzothiazine) Tracking the Biosynthetic Pathway of Trichochromes, the Characteristic Pigments of Red Hair. J. Org. Chem. 2001, 66, 6958-6966. 

H- 1,4-Thiazines and benzothiazines undergo oxidation to dehydro dimers (83) and (84) which are of considerable interest as they are the parent chromophores of the trichosiderin (trichochrome) pigments which occur in mammalian red hair and in the feathers of some birds (74T2781). In the case of monocyclic thiazines, reagents such as nitrobenzene or picric acid are required, but air oxidation is sufficient in the bicyclic series. It is curious that whereas aerial oxidation of the ester (85) gives both the dehydro dimers (86) and (87), ethyl azodicarboxylate only yields the tautomer (87) <70AC(R)35l). 

The natural colour of animal fibre is closely related to the character of environment in which the animal lives [19]. Wool lots completely free of dark fibres do not exist [20]. In animal (and human) hair two kinds of pigments occur, namely eumelanin (responsible for black, dark brown and grey colours and commonly referred to as melanin) and pheomelanin (present in yellow, reddish-brown and red hair). Both are thought to be formed by different mechanisms and chemically differed [21]. Eumelanin is formed by enzymatic (tyrosinase) oxidation of tyrosine and polymerisation of several oxidation product [22]. Pheomelanin occurs in form of discrete grannules. Melanin grannules can occur in the cortex or in the cuticle. 

The 1,4-benzothiazine ring is the basic unit for the phaeomelanins and trichochrome melanin pigments found in mammals, particularly in red hair... 

Both eumelanins and pheomelanins are polymeric and are believed to be formed from a common metabohe pathway. Both of these polymeric pigments contain polypeptide chains with similar amino acids [66]. The red hair melanin contains more sulfur (as 1,4-benzothiazine units) than the brown-black melanins. 

The natural color of hair depends primarily on two pigments melanin, a dark pigment, and phaeomelanin, a red-orange pigment. Light blonde or white hair... 

Standards for the mineral content of hair should take into consideration the color of the hair because certain minerals are constituents of hair pigments. For example, blonde hair has lower ratios of zinc to copper than dark shades of hair. Also, red hair contains more iron than other colors, because Iron Is present in the red pigment. Also, age and sex can affect hair analyses. 

Generally, the phenotype that predisposes an individual to an increased risk of skin cancer is red or blond hair, blue eyes, and fair skin. These characteristics are surrogate measure of the sensitivity of the skin to sun exposure and the tendency to develop nevi, freckles, and sunburns based on the skin type. Freckles, which may appear abruptly after the first high dose of UV radiation sun exposure, represent clones of mutated melanocytes, and their presence is associated with an increased risk of melanoma.12 The Fitzpatrick classification of skin type is used to determine the response pattern of the skin to UV radiation and assess the risk for melanoma. There are six Fitzpatrick skin types Type I skin always burns and never tans, type II skin burns easily and tans rarely, type III skin burns sometimes and tans usually, type IV skin burns rarely and always tans, type V skin always tans and is moderately pigmented (brown), and type VI skin always tans and is darkly pigmented (black). Fitzpatrick I and II skin types are commonly affected by NMSC and MM. The susceptibility to skin cancer, both NMSC and MM, is related to the melanin content of the skin and the skin s response to UV radiation. 

Cobaltous nitrate [ColNO l bH O], also known as cobalt nitrate, is a red crystal that absorbs moisture. It is used in inks, pigments, animal feed, soil enhancers, and hair dyes. 

Copper helps form red blood cells and connective tissues. Copper is a cofactor enzyme that initiates metabolic reactions in the body. Copper is necessary to produce norepinephrine and dopamine (neurotransmitters). Copper is absorbed in the intestine. Foods rich in copper are shellfish (crabs and oysters), liver, nuts, seeds (sunflower, sesame), legumes, and cocoa. Copper deficiency results in anemia, causes decreased hair and skin pigmentation, decreased white blood count, intolerance to glucose, and mental retardation in young patients. Excess serum levels of copper indicate Wilson s disease, which results in the accumulation of copper in the liver, brain, cornea, and kidney. 

Although the link between skin cancer and exposure to sunlight is very strong, the susceptibility of individuals to the carcinogenic effect of UV radiation varies depending on several factors including skin pigmentation, age, sex, and phenotype. Particularly, factors such as fair skin, blue eyes, red or fair hair, and inability to tan have been linked to increased risk of NMSC in several studies (270-276). 

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