Abstract

IDENTIFICATION OF MELANIN

Adila Salih Elobeid*, Afaf Kamal-Eldin and Adil M. Haseeb

Abstract

Melanin is a ubiquitous natural pigment that is present in many organs in different species. It is well recognized as a UV absorber and as a protective molecule. It harbors stable intrinsic free radicals and binds metals, and molecules. It shows a broad band optical spectrum and a single- x-ray line in addition to a paramagnetic behavior. It is water and organic-solvent insoluble and is highly resistant to chemical attack; thus it has survived through millennia as an intact chemical entity. Electrically and optically responsive electron spins and protonic conductors exit in melanin and it is normally conductive as well as photo responsive. Currently melanin is described as an oligmeric polymer made of various combinations of indolic monomers. Active and protective physiological roles have been identified, and assigned to biologically constituted melanin as well as to internally or externally administered melanin. It has often been suggested as possible pharmacological agent in certain physiological and disease situations. Many diseases are accompanied by an increase or decrease of melanin production by the living organism. It has increasingly been suggested as a component in bio-inspired electronics and as a biological interface. This review brings together data on the biosynthesis, physicochemical characteristics, structure and morphological properties of melanin. Contrary to most of the well-known biological molecules melanin is not clearly definable as a single chemical structure with a recognizable molecular weight. General characteristics of the molecule that makes melanin identifiable as a specific chemical entity are discussed here.

Keywords: Biosynthesis, morphological, physicochemical properties, spectroscopy, melanin.