Pheomelanins

Pheomelanins are a type of melanin pigment found in humans and other animals. They are responsible for red and yellow colors in hair, skin, and feathers. Unlike eumelanins, which are black and brown, pheomelanins are characterized by their sulfur content. This sulfur is incorporated into the pigment's structure during its synthesis, leading to its distinct spectral properties.

The production of pheomelanin is controlled by genetic factors, particularly variations in the melanocortin-1 receptor (MC1R) gene. Individuals with certain MC1R variants are more likely to produce pheomelanin, resulting in lighter hair colors like red and blonde, as well as fair skin that tends to freckle and burn easily in the sun. Conversely, individuals with MC1R variants that favor eumelanin production will have darker hair and skin tones.

Pheomelanins play a role in photoprotection, though generally to a lesser extent than eumelanins. While both types of melanin absorb ultraviolet (UV) radiation, eumelanins are more effective at scattering and dissipating this energy. The presence of pheomelanin can, under certain conditions, contribute to the formation of reactive oxygen species when exposed to UV light, potentially increasing the risk of skin damage. Therefore, individuals with a higher proportion of pheomelanin in their skin may be more susceptible to sun damage and skin cancers. The study of pheomelanins is important for understanding skin pigmentation, hair color variation, and the biological basis of sun sensitivity.