Neuromelanin is similar to
eumelanin, but its function in the brain is only partially understood.
That analysis not only reported one of the first demonstrations of pheomelanin (the brown version of melanin) in non-vertebrates, but it also found that the grasshoppers kept on brown soil were rich in pheomelanin, while the grasshoppers kept on gray stones were rich in
eumelanin (the black version of melanin) (see Galvan et al.
SOURCE: Q.LI ET AL/SCIENCE 2012 Pigment
Eumelanin Pheomelanin Mixed Mixed Melanosome shape Found in Red- Tufted Double- Microraptor winged titmouse crested blackbird cormorant
In the reaction, tyrosine is first oxidized to dopaquinone, which either cyclises to give a dihydroxyindole precursor of black or brownish
eumelanins or reacts with cysteine to give a precursor of reddish brown pheomelanin [81].
Maresca et al., "The
eumelanin intermediate 5, 6-dihydroxyindole-2-carboxylic acid is a messenger in the cross-talk among epidermal cells," Journal of Investigative Dermatology, vol.
The most common form of biological melanin is
eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids.
Aromatic amino acids are essential to synthesis of melanins responsible for hair pigmentation-pheomelanin (red, brown) and
eumelanin (black).
Since all melanin-based color is formed by a combination of two melanin pigments,
eumelanin (which makes dark colors) and pheomelanin (which makes yellow to red colors), they speculated that
eumelanin may be more susceptible to degradation than pheomelanin pigments, which overtime could lead to reduced proportion soft his pigment in the feathers, ultimately resulting in higher reflectance at longer wavelengths (i.e., giving the feathers a slightly reddish color).
Light-skinned redheads with freckles and an inability to tan have trouble producing the black-grown pigment
eumelanin, which absorbs harmful UV rays - instead producing the red-yellow pigment pheomelanin which provides a weak UV shield.
It is true that darker skin offers some protection against ultraviolet radiation because it contains higher melanin and
eumelanin (brown-black pigment) content, which reduces the risk of cancer caused by sun exposure, or ultraviolet radiation.
Melanin is the substance that gives skin, hair and eyes their colour, dependent on the relative amounts of the two forms of melanin,
eumelanin and pheomelanin.