JOURNAL OF COSMETIC SCIENCE 508 (14) Kukizo Miyamoto, Hirotsugu Takiwaki, Greg G. Hillebrand, and Seiji Arase, Development of a digital imaging system for objective measurement of hyperpigmented spots on the face, Skin Res. Tech., 8(4), 227–235 (2002). (15) S. Parvez, M. Kang, H. S. Chung, C. Cho, M. C. Hong, M. K. Shin, and H. Bae, Survey and mechanism of skin depigmenting and lightening agents, Phytother. Res., 20(11), 921–934 (2006). (16) Nippon Hifuka Gakkai Zasshi, Inhibitory effect of arbutin on melanogenesis—Biochemical study us- ing cultured B16 melanoma cells, 101(6), 609–613 (1991). (17) J. Lee, E. Jung, J. Lee, S. Huh, Y. C. Boo, C. G. Hyun, Y. S. Kim, and D. Park, Mechanisms of melano- genesis inhibition by 2,5-dimethyl-4-hydroxy-3(2H)-furanone, Br. J. Dermatol.157(2), 242–248 (2007). (18) D. S. Kim, S. H. Park, S. B. Kwon, Y. H. Joo, S. W. Youn, U. D. Sohn, and K. C. Park, Temperature regulates melanin synthesis in melanocytes, Arch. Pharm. Res., 26(10), 840–845 (2003). (19) P. Donsing, N. Limpeanchob, and J. Viyoch, Evaluation of the effect of Thai breadfruit’s heartwood extract on melanogenesis-inhibitory and antioxidation activities, J. Cosmet. Sci., 59(1), 41–58 (2008). (20) H. C. Lin, B. H. Shieh, M. H. Lu, J. Y. Chen, L. T. Chang, and C. F. Chao, A method for quantifying melanosome transfer effi cacy from melanocytes to keratinocytes in vitro, Pigment Cell Melanoma Res., 21(5), 559–564 (2008). (21) A. S. Breathnach, Melanin hyperpigmentation of skin: Melasma, topical treatment with azelaic acid, and other therapies, Cutis, 57(Suppl 1), 36–45 (1996). (22) S. M. Bulengo-Ransby, C. E. Griffi ths, C. K. Kimbrough-Green, L. J. Finkel, T. A. Hamilton, C. N. Ellis, and J. J. Voorhees, Topical tretinoin (retinoic acid) therapy for hyperpigmented lesions caused by infl ammation of the skin in black patients, N. Engl. J. Med., 328(20), 1438–1443 (1993). (23) N. Kollias, R. Gillies, C. Cohén-Goihman, S. B. Phillips, J. A. Muccini, M. J. Stiller, and L. A. Drake, Fluorescence photography in the evaluation of hyperpigmentation in photodamaged skin, J. Am. Acad. Dermatol., 36(2 Pt 1), 226–230 (1997). (24) T. Bishop, A. Ballard, H. Holmes, A. R. Young, and S. B. McMahon, Ultraviolet-B induced infl amma- tion of human skin: Characterisation and comparison with traditional models of hyperlagesia, Eur. J. Pain, 13(5), 524–532 (2009). (25) S. A. Miller, S. G. Coelho, B. Z. Zmudzka, H. F. Bushar, Y. Yamaguchi, V. J. Hearing, and J. Z. Beer, Dynamics of pigmentation induction by repeated ultraviolet exposures: Dose, dose interval and ultra- violet spectrum dependence, Br. J. Dermatol., 159(4), 921–930 (2008). (26) M. A. Pathak and D. L. Fanselow, Photobiology of melanin pigmentation: Dose/response of skin to sunlight and its contents, J. Am. Acad. Dermatol., 9(5), 724–733 (1983).

J. Cosmet. Sci., 60, 509–518 (September/October 2009) 509 A role of the anteiso branch of 18-MEA in 18-MEA/SPDA to form a persistent hydrophobicity to alkaline-color-treated weathered hair HIROTO TANAMACHI, SHIGETO INOUE, SHINICHI TOKUNAGA, HISASHI TSUJIMURA, NORIYUKI TANJI, MASASHI OGURI, and TAICHI HABE, Beauty Research Center, Kao Corporation, 2-1-3, Bunka, Sumida-ku, Tokyo 131-8501, Japan (H.T., S.T.) Analytical Science Research Laboratories, Kao Corporation, 1334 Minato, Wakayama-shi, Wakayama, 640-0112, Japan (S.I., N.T, T.H.) and Analytical Science Research Laboratories, Kao Corporation, 2606 Akabane, Ichikai, Haga, Tochigi 321-3497, Japan (H.T., M.O.). Accepted for publication May 18, 2009. Synopsis The effect of the anteiso-branch moiety of 18-MEA (18-methyleicosanic acid) to create a persistent hydro- phobicity of alkaline-color-treated weathered hair treated with 18-MEA/SPDA (stearoxypropyldimethyl- amine) was investigated by comparing a straight-chain fatty acid (n-heneicosanoic acid, n-HEA) and an iso-branch fatty acid (19-methyleicosanic acid, 19-MEA) with the anteiso-branch fatty acid (18-MEA), using dynamic contact angle measurements, quantifi cation of 18-MEA by LC/MS, and temperature controlled atomic force microscopy (AFM). The dynamic contact angle measurements indicated that the anteiso-branch moiety of 18-MEA is critical for the creation of a persistent hydrophobicity to alkaline-color-treated weath- ered hair. The temperature-controlled AFM investigations revealed that the anteiso-branch moiety of 18-MEA in the 18-MEA/SPDA system produces a persistent hydrophobicity to alkaline-color-treated weathered hair by providing higher fl uidity to the upper region of the 18-MEA/SPDA layer. INTRODUCTION Since healthy and beautiful hair is of interest to many females who have had their hair damaged by chemical treatments, heat styling, and environmental factors, various hair care products have been developed for improving the beauty of hair. Detailed knowledge of the surface structure and properties of hair is essential for developing unique hair care technologies. The cuticle is the outer surface of the hair fi ber, protecting the cortex. The outermost surface of the cuticle cells has been suggested to be covered by a monolayer of covalently bound fatty acids, a major component of which is 18-MEA (18-methyleico- sanic acid). 18-MEA has been subjected to study for years in hair research science, since the discovery of its presence on keratinous fi bers (1–3). 18-MEA is thought to be covalently