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By: Zoe Diana Draelos, MD
Posted: January 7, 2009, from the January 2009 issue of Skin Inc. magazine.
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Aleosin. Aleosin is a botanical low-molecular-weight glycoprotein obtained from the aloe vera plant. It is a natural hydroxymethylchromone that functions by inhibiting tyrosinase.9,10 In contrast to hydroquinone, it shows no cell cytotoxicity; however, it has a limited ability to penetrate the skin due to its hydrophilic nature. It is sometimes mixed with arbutin, described below, to enhance its skin-lightening abilities.
Arbutin. Arbutin is obtained from the leaves of the Vaccinium vitis-idaea (lingonberry) and other related plants. It is a naturally occurring gluconopyranoside that causes decreased tyrosinase activity without affecting messenger RNA expression.11 It also inhibits melanosome maturation. Arbutin is not toxic to melanocytes and is used in a variety of pigment-lightening preparations in Japan at concentrations of 3%. Higher concentrations are more efficacious than lower concentrations, but a paradoxical pigment-darkening may occur due to skin irritation. Synthetic versions of arbutin, such as deoxyarbutin, may offer enhanced efficacy.
A client need
Skin-lightening is a definite challenge. Many substances have been reported to inhibit melanin production in vitro but these same results are not seen in vivo. Melanocytes are extremely difficult cells to grow in culture, and it is possible that many skin-lightening ingredients that did not produce clinical results were toxic to the cultured melanocytes. It is important that skin-lightening ingredients only suppress pigment production and do not destroy the melanocytes. Melanocyte destruction results in permanent skin-lightening, which must be avoided at all costs. Melanocytes are present at birth, and do not divide or reproduce during an individual’s lifespan, making cell-preservation extremely important. Furthermore, cell cultures do not have the stratum corneum barrier to prevent penetration of skin-lightening ingredients. For a pigment-lightening preparation to be effective, it must reach the melanocyte deep within the skin. This is the limiting factor in most skin-lighteners.
There is no doubt that pigment-lightening will be a client need that continues to grow during the next decade. Attractive, youthful skin is even in color without discrete areas of darkening. Sun avoidance is the best preventive measure, but the human desire to seek the sun, especially during youth, will make skin-lightening a challenge that must be overcome.
1. RM Halder and GM Richards, Management of dischromias in ethnic skin, Dermatol Ther 17 151–157 (2004)