346 .JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS SUMMARY A review of hair bleaching describing reactions of bleach agents with the proteins of human hair and with hair pigments is presented. Support for diffusion-controlled oxidative cleavage of the disulfide bond during bleaching is described. Evidence for oxidation of cystyl residues in hair through S--S fission instead of C--S fission is presented and possible end products of the oxidation reaction are described. The low yields of prod- ucts (pyrolie acids) isolated from the oxidation of melanins suggest that these species are themselves sensitive to oxidation, and/or that several different functional groups in the pigment macromolecule may be suscep- tible to attack by oxidizing agent. ACKNOWLEDGMENT The author would like to acknowledge Dr. M. L. Douglass for care- fully reading this manuscript and for helpful suggestions. (Received December 21, 1970) REFERENCES (1) Maclaren, J. A., Leach, S. J., and Swan, J. M., A study of some problems in protein chemistry using new (non-hydrolytic) methods for the determination of thiol and disul- fide, J. Text. Inst., 51, T 665-7 (1960). (2) Maclaren, J. A., Savige, W. E., and Sweetman, B. J., Disulfide monoxide groups in oxi- dized proteins, Aust. J. Chem., 18, 1655-65 (1965). (3) Robbins, C., Infrared analysis of oxidized keratins, Text. Res. J., 37, 811-3 (1967). (4) Alter, H., and Bit-Alkhas, M., Infrared analysis of oxidized keratin, Ibid., 39, 479-81 (1969). (5) Nachtigal, J., and Robbins, C., Intermediate oxidation products of cystine in oxidized hair, Ibid., 40, 454-7 (1970). (6) Zahn, H., Chemical processes in the bleaching of wool and human hair with hydrogen peroxide and peroxy acids, ]. Soc. Cosmet. Chem., 17, 687-701 (1966). (7) Robbins, C., and Kelly, C., Amino acid analysis of cosmetically altered hair, Ibid., 20, 555-64 (1969). (8) Nicolaus, R. A., Comments on Howard S. Mason's Paper "The Structure of Melanin," in Montagna, W., and Hu, F., Advances in Biology of Shin, The Pigmentary Sy,•tem, Vol. 8, Perga•non Press, New York, 1966, pp. 313-4. (9) Mason, H. S., The Structure of Melanin, in Montagna, W., and Hu, F., Advances in Biology o/Shin, The Pigmentary System, Vol. 8, Pergamon Press, 1966, pp. 293-312, and references therein. (10) Wolfram, L., Hall, K., and Hui, I., The mechanism of hair bleaching. J. Soc. Cosmet. Chem., 21,875-900 (1970). (11) Flesch, P., Chemical studies of the iron pigments of red hair and feathers, Ibid., 19, 675-81 (1968). (12) Prota, G., Schevillo, G., and Nicolaus, R. A., On the structure of trichosi(lerins, Rend. Accad. Sci. Fis. Mat., Naples. 35, 1-4 (May, 1968).

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