Binding Complexation and Medicinal Aspects of Melanin

Binding studies combined with ESR spectroscopy have revealed the mechanism of the interaction of metal ions with melanins which indicates the formation of a chelate complex between di- and trivalent diamagnetic metal ions and o-semiquinone radical centers on the pigment polymer (85, 124). This interaction often results in an increase of total free radical concentration. Furthermore, the binding capacity varies for melanins of different origins with the number of reactive sites (230). 

The melanin of sepia is found in the ink sac of cuttlefish. Aristotle in his book Historia Animalia mentioned that instead of intestines molluscs have an organ known as the mytin where a black substance is found which is especially abundant in cutdefish they put forth this black substance when frightened, particularly the cuttlefish . The ink has considerable staining power, and is alkaline and odorless. When fresh it disperses readily in water and is partly soluble in alkali, but insoluble in acid. This biological function of melanin appears to be defensive but the mechanism is uncertain (270). However, like other pigments, melanin can be utilized for camouflage purposes in insects and fishes. 

Epidermal melanin synthesis is a multistage process involving fast or slow reactions, some of which are enzyme catalyzed, others requiring only oxygen. The process is controlled by pH, temperature, redox 

Melanocjdes are dendritic cells which are wedged between the basal cells of the epidermis. They derive from neural crest (i.e. at a high point of action of the nervous system) and have complex structures mainly made up of protein and various oxydase systems, including tyrosinase (160). 

Although the melanosome theory has been accepted in general, some authors support a mitochondrial origin of the melanin granules (282). 

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