JOURNAL OF COSMETIC SCIENCE 12 Generally, most of the lipophilic agents pass the stratum corneum through an intercellular lipid bilayer pathway (24). The destabilization of such a lipid bilayer will enhance the lipid pathway’s permeability to lipophilic agents such as artocarpin, the major component of the extract. Moreover, the small droplet size and low viscosity of the nanoemulsion make it an excellent carrier for enhancing percutaneous uptake of lipophilic compounds through the stratum corneum and/or hair follicles. This is because the number of internal droplets that can interact on a fi xed area of the targeted sites will increase when the drop- let size and viscosity decrease (25). Therefore, the higher effi cacy of the nanoemulsion formulation could be the result of the combined effects of the enhancers of skin perme- ation as well as the small droplet size of the nanoemulsions. As mentioned previously, artocarpin has depigmenting effects on UVB-induced hyper- pigmentation on the dorsal skin of brownish guinea pigs (7). In the present study, there- fore, it is possible to conclude that the melanogenesis-inhibitory activity of A. incisus extract is also involved with artocarpin. Generally, the ideal of depigmenting agents should have a potent, rapid, and selective bleaching effect on hyperactivated melanocyte cells and carry no short- or long-term side effects. The present in vivo study showed that reduced hyperpigmentation was observed following topical applications of the extract for four weeks and that the treated areas (UVB-induced hypigmentation) could return to close to their original color after stopping treatment for four weeks (Figure 7E). This fi nding implies that no permanent dysfunction of skin cells is caused by the extract of A. incisus when the optimal concentration is used. Furthermore, visible edema or scaling was Figure 8. (A) Averaged melanin values measured by a Mexameter MX® 18 at the UV-induced hyperpig- mented dorsal skin areas from the day after tanning (week 0) through six weeks of application. (B) The degree of depigmentation (ΔM-value) after application of the prepared nanoemulsion containing 0.02% w/w extract or the solution containing 0.02% w/w extract for six weeks. Each point or bar represents mean ± S.D. (n = 3). Student’s t-test showed a signifi cant difference between the two formulations, ** p0.01.

REDUCTION OF HYPERPIGMENTATION BY A. INCISUS EXTRACT 13 not observed at any dorsal skin sites treated with either the nanoemulsion containing the extract or the extract solution during any of the experimental days. CONCLUSIONS Nowadays, botanical extracts are playing an increasingly important role in cosmetics. Together with being used in suitable formulations, the effi cacy of such extracts indicates their role as enhancers. Nanoemulsions are one of the attractive formula options for appli- cation in cosmetics, as their small droplet size can promote penetration of active ingredi- ents into the skin. Our study indicates that a formulated nanoemulsion containing A. incisus extract has the potential for application in skin depigmentation. It could act as a remedy for hyperpig- mentation in UVB-induced hyperpigmentation. Side effects such as permanent depig- mentation and edema were not found during application for six weeks. However, further clinical studies of the formulated product should be performed to ensure its effi cacy and safety before marketing in the future. ACKNOWLEDGMENT Financial and facility support from Thailand Research Fund–Master Research Grants (TRF-MAG) and the Center of Excellence for Innovation in Chemistry (PERCH-CIC), Commission on Higher Education, Ministry of Education, is gratefully acknowledged. REFERENCES (1) A. G. Pandya and I. L. Guevara, Disorders of hyperpigmentation, Dermatol. Clin., 18, 91–98 (2000). (2) N. Lawrence, S. E. Cox, and H. J. Brody, Treatment of melasma with Jessner’s solution versus glycolic acid: A comparison of clinical effi cacy and evaluation of the predictive ability of Wood’s light examina- tion, J. Am. Acad. Dermatol., 36, 589–593 (1997). (3) P. E. Grimes, Melasma: Etiologic and therapeutic considerations, Arch. Dermatol., 131, 1453–1457 (1995). (4) N. P. Sanchez, M. A. Pathak, S. Sato, T. B. Fitzpatrick, J. L. Sanchez, and M. C. Mihm, Jr., Melasma: A clinical, light microscopic, ultrastructural, and immunofl uorescence study, J. Am. Acad. Dermatol., 4, 698–710 (1981). (5) P. Donsing, N. Limpeanchob, and J. Viyoch, Effect of Thai breadfruit’s heartwood extract on melano- genesis-inhibitory and antioxidation activities, J. Cosmet. Sci., 59, 41–58 (2008). (6) K. Shimizu, R. Kondo, K. Sakai, S. H. Lee, and H. Sato, The inhibitory components from Artocarpus incisus on melanin biosynthesis, Planta Med., 64, 408–412 (1998). (7) K. Shimizu, R. Kondo, and K. Sakai, The skin-lightening effects of artocarpin on UVB-induced pigmentation, Planta Med., 68, 79–81 (2002). (8) E. J. Windhab, M. Dressler, K. Feigl, P. Fischer, and D. Megias-Alguacil, Emulsion processing: From single drop deformation to design of complex processes and products, Chem. Eng. Sci., 60, 2101–2113 (2005). (9) P. Izquierdo, J. Esquena, T. F. Tadros, C. Dederen, M. J. Garcia, N. Azemar, and C. Solans, Formation and stability of nano-emulsions prepared using the phase inversion temperature method, Langmuir, 18, 26–30 (2002). (10) T. Tadros, R. Izquierdo, J. Esquena, and C. Solans, Formation and stability of nano-emulsions, Adv. Colloid Interface Sci., 108–109, 303–318 (2004). (11) T. Pitaksuteepong, A. Somsiri, and N. Waranuch, Targeted transfollicular delivery of artocarpin extract from Artocarpus incisus by means of microparticles, Eur. J. Pharm. Biopharm., 67, 639–645 (2007).