Content of Tryptophan in Human Hair

Previous papers have shown that tryptophan is involved in the process of melanogenesis (Musajo et al., 1966; Musajo et al., 1969; De Antoni et al., 1970; Allegri et al., 1972; De Antoni et al., 1974; Costa et al., 1975). In fact, tryptophan and also kynurenines and indolic hydroxylated metabolites form melanins by the action of tyrosinase from Sepia officinalis and of poly-phenoloxydase from potato and from Psalliota campestris mushroom (Musajo et al., 1966; Musajo et al., 1969; De Antoni et al., 1970). The study of the precursors which form during the process of melanization of tryptophan revealed that one of the substances which give rise to the formation of black pigments is 3-hydroxykynurenine (Musajo et al., 1966; Musajo et al., 1969).