CHEMICAL CHARACTERIZATION OF MELANINS IN SHEEP WOOL AND HUMAN HAIR

The color of hair and wool in mammals and feathers in birds is mostly determined by the quantity and quality of melanins that are synthesize d in follicular melanocytes and transferred to keratinocytes. There ar e two chemically distinct types of melanin pigments: the black to brow n eumelanins and the yellow to reddish pheomelanins. Melanins in sheep wool and human hair of various colors were characterized by HPLC meth ods to estimate 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-derived units in eumelanins and benzothiazine units in pheomelanins. Melanins were also characterized by spectrophotometric methods after differenti al solubilization in alkalies. It was demonstrated that 1) black wool iri Asiatic sheep contains eumelanin with the DHICA content similar to black mouse melanin, while black to brown melanins from human hair co ntain much lower ratios of DHICA-derived units, comparable to the slat y mutation in mice, 2) dark brown to brown hair in human contains eume lanin whose chemical properties are indistinguishable from those of bl ack hair, 3) dark red wool and red human hair contain pheomelanic pigm ents whose chemical properties are rather different from those of yell ow pheomelanins in mice, and 4) light brown, blonde, and red hairs in human can be differentiated from each other with this methodology.