J. Soc. Cosmetic Chemists, 19• 675-681 (Sept. 16, 1968) Chemical Studies of the Iron Pigments of Red Hair and Feathers PETER FLESCH, M.D., Ph.D. t Synopsis--The iron pigments of red hair and feathers consist of a protein linked to a non- protein chromophore. The chromophore is responsible for the characteristic properties of the siderins, i.e., the iron pigments obtained by extraction with hot acids their indicator-like properties and characteristic absorption bands are due to this grouping. This work does not support the theory of the participation of tyrosinase in the synthesis of the red hair pigments. Earlier evidence advanced in support of this view is subjected to a critical re-evaluation. INTRODUCTION In previous publications (1-3), attention has been called to iron pigments in human red hair and red chicken feathers. These substances are different from all other known epidermal pigments. It is believed that they are the major pigments in red hair and feathers and that their synthesis differs from that of the black melanins. Although data in this field are scant, it already has been shown that the appearance of the particles elaborating the red hair pigment, the melanosomes in the red hair matrix, differs from that of their black counterparts (4). This paper presents some recent findings on the chemical composition of the iron pigments, extending and reinterpreting some previous data. As the suggestion that red pigments are the products of tyrosinase activity is not accepted, some of the evidence adduced in support of this theory (5) will be subjected to critical evaluation. * Investigation supported by Public Health Service Research Grant AM 10046 from the Division of Research Grants, National Institutes of Health, Bethesda, Md. • Department of Dermatology, School of Medicine, University of Pennsylvania, Phila- delphia, Pa. 19104. 675

676 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 0.5 0.4 0.3 Absorbance 0.2 0.1 540 '80 mp. 1 3 5 7 9 11 13 15 17 Tube number Figure 1. Elution of dialyzed trichosiderin derivative with 0.1 N NaOH from a Sephadex G-50 column EXTRACTION OF SIDERINS The preparation of the iron pigments has been described in previous publications (2, 3) only a brief summary will be presented. Red hair or feathers are washed with chloroform and acetone, dried, and extracted with boiling 0.1 N HC1. The length of extraction is 1-3 hours for hair, 10-15 minutes for feathers. The extract is filtered and neutralized to pH 7, and the precipitated pigment is centrifuged and washed with water. With this procedure one obtains the so-called siderins, i.e., the indi- cator-type pigments (red below pH 2, yellow at all higher pH's) with a neutral isoelectric point. The siderins are derivatives of the "protopiõ- ments," the large nonindicator yellow-brown compounds with nonspecific absorption spectra, obtained with milder methods of extraction (3). Boiling in acids is not essential to convert the protopigments to the