polypyrrole, polyaniline and their copolymers. The type of melanin differs according to the proportion and banding pattern of these smaller molecular components. Melanin is a conductive biopolymer and a neuropeptide that generates an influence on the neural activity and permits the conduction of light, heat, radiation and kinetic energy.

There are three common types of melanin. Pheomelanin is found in abundance in fair- skinned individuals. This type of melanin generates a pinkish- red color and is generously present in people with red hair. Eumelanin polymers are found in the hair and skin of dark-skinned people and are further categorized as brown and black eumelanin. Decreased quantity of the black eumelanin polymers leads to the graying of the hair, while a decrease in the brown eumelanin results in blond or yellow- colored hair. Eumelanin polymers are the most common type of melanins present in humans and a reduction in these pigments result in a condition called Albinism. Neuromelanin is a dark pigment present in the neurons of the brain nuclei such as the Substantia Nigra, Locus Ceruleus, the nucleus associated with the Vagus nerve and the Raphe nucleus of the Pons Medulla. The neuromelanins are usually not found at birth, but evolve gradually during maturation to adulthood. The decrease or loss of these pigmented neurons are indicative of degenerative diseases, like the Alzheimer’s.

Besides deficiency, the molecular weight of melanin can be decreased due to various factors, like oxidative stress or exposure to light. A decrease in the molecular weight or an impairment in the polymerization of the melanin molecule results in the conversion of the normally anti-oxidant polymer, into a pro-oxidant one. These pro- oxidant melanin molecules are implicated in macular degeneration, affecting the eye and melanoma, a type of skin cancer.


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