SAN DIEGO – Expect botanicals to play an increasing role in the development of cosmeceuticals to treat melasma, Dr. Zoe D. Draelos said at the annual meeting of the American Academy of Dermatology.
"Combinations of kojic acid, emblica, and glycolic acid are now available in the cosmeceutical market," said Dr. Draelos, a clinical dermatologist and researcher in High Point, N.C. "This combination uses several mechanisms of pigment lightening, and clinical results are pretty much on par with hydroquinone."
Perhaps the most effective pigment-lightening agent in the over-the-counter market, she said, is kojic acid, a hydrophilic fungal derivative evolved from Acetobacter, Aspergillus, and Penicillium. Obtained from mushrooms, it inhibits tyrosinase by binding to copper. "Kojic acid is thought to be the most effective active [agent] behind hydroquinone," said Dr. Draelos, who is also a consulting professor of dermatology at Duke University in Durham, N.C.
Licorice extracts are also widely used for the treatment of melasma, particularly the licorice-derived flavonoids liquiritin and isoquercetin. "Glabridin is the most commonly used substance," Dr. Draelos said. "It is commonly combined with kojic acid and other active agents in order to create a sort of cocktail to multidimensionally inhibit pigment production."
Sometimes kojic acid and licorice extracts are combined with arbutin, which is obtained from the bearberry plant. "Interestingly enough, arbutin is very similar to glycosylated hydroquinone, and it has been used in Indian tribal medicine," she said. The most active form is deoxyarbutin, which is synthetic, inhibits tyrosinase, and has no cytotoxicity.
Soy, which interferes with melanosome transfer, is another natural substance that is being used to treat melasma. Fresh soy milk contains soybean trypsin inhibitor (STI), a polypeptide that decreases protease-activated receptor-2, a protein that is important in the regulation of pigmentation. STI reduces keratinocytes and decreases pigmentation.
The newcomer for the treatment of melasma is emblica, also known as Indian gooseberry. This substance is high in vitamin C and tannins, but also contains flavonoids, kaempferol, ellagic acid, and gallic acid. "It is thought that the tannins contained within emblica inhibit melanogenesis in human melanocyte cultures," Dr. Draelos said. "It is also a potent antioxidant."
She concluded her presentation by noting that although melasma is an important dermatologic need, "the depth of pigment is key to treatment success. Sunscreens, pharmaceuticals, cosmeceuticals, and surgical treatments may be used individually or in combination to treat melasma."
Dr. Draelos disclosed that she has received research consulting funds from Beiersdorf, L’Oréal, Neocutis, Neutrogena, Nu Skin, Procter & Gamble, and Syneron.