J. Cosmet. Sci., 63, 43–54 ( January/February 2012) 43 Fairness via formulations: A review of cosmetic skin-lightening ingredients R. KAMAKSHI, Cavinkare Research Centre, Ekkatuthangal, Chennai 600 032, India. Accepted for publication August 31, 2011. Synopsis Skin-lightening cosmetics are in big demand across Asia, and the quest for fairness has led to identifi cation of many new ingredients. The mechanisms underlying pigmentation have been researched extensively and the knowledge is being updated regularly. This review serves to list the ingredients that are commercially available for that purpose and the modes of action through which the lightening is effected. Skin-lightening ingredients are also classifi ed based on their sources it is signifi cant that far more botanicals have made the list than have synthesized compounds. Tyrosinase inhibition as a means of skin lightening is still the most reported method, followed by other methods such as Mitf inhibition, down regulation of MC1R activity, interference with melanosomal transfer, and melanocyte loss. INTRODUCTION The defi nition of fair skin is given as “not dark and free from spots, specks, dirt or imper- fection unblemished clean pure.” The booming cosmetics industry in recent decades can be partly attributed to the elusive search for fair and fl awless skin (1,2). With the vast information that is accessible in the 21st century, one has an option to choose methods ranging from that of Cleopatra (soaking in donkey milk that is rich in AHA) to recent advances in skin-lightening procedures such as dermabrasion, ultrasound, and laser ther- apies, to name a few (3–9). Skin-lightening agents are any ingredient or combination of ingredients that interfere in any step of the melanogenesis pathway, melanin transfer, or desquamation that results in lowering pigmentation on the surface of the skin (10). Skin-lightening cosmetics are in big demand across the world, and this review serves to list the ingredients that are com- mercially available for that purpose and the modes of action through which the lighten- ing is effected. There are many reports of skin-lightening agents obtained from both natural and synthetic sources. However, many ingredients in their original form may not be compatible in cosmetic formulations for application to the skin due to various factors such as cytotoxicity, insolubility, instability, and their sensitive nature to external condi- tions. However, consistent efforts are being made by industry to arrive at compatible, minimally toxic, and highly effi cacious ingredients that serve the purpose.

JOURNAL OF COSMETIC SCIENCE 44 PIGMENTATION IN SKIN The color of our skin is due to the polymeric, amorphous, non-proteinaceous pigment called melanin. Melanin is produced in the skin through a biochemical process called melanogenesis. Dermal melanin is produced by melanocytes, which are found in the stra- tum basale of the epidermis. The pathway of melanogenesis as elucidated by Raper (18) and Mason (19) is shown below (Figure 1). The difference in skin color between fair people and dark people is due not to the number (quantity) of melanocytes in their skin, but to the melanocytes’ level of activity (quantity and relative amounts of eumelanin and pheomelanin). In skin that exhibits a dark color the melanosomes are well distributed in the keratinocytes, which absorb radiation (11). Pigmentation in skin is determined by various physiological processes occurring at different stages (12): (a) Development of melanocytes (b) Density of melanocytes (c) Expression of the enzymatic and structural constituents of melanosomes (d) Synthesis of melanin (e) Transport of melanosomes to dendrites (f) Transfer of melanosomes to keratinocytes (g) Distribution of melanin in the supra basal layers of the skin Figure 1. Raper-Mason pathway of melanogenesis.