MELVILLE, N.Y.—Researchers from Clinique, Estee Lauder and Kobe Skin found a cosmetic formula containing Dianella ensifolia, a grass-like plant, produced an increase in the rate of fading compared to the two pharmaceutical treatments containing hydroquinone (J Cosm Dermatol. 2010;9(2)89-95). Skin hyperpigmentation, and the reactions that precipitate it, have been linked to free radicals, as free radical scavengers can slow that hyperpigmentation. Researchers have screened several hundred plant extracts for antioxidants and discovered one that is both a strong antioxidant and can reduce skin hyperpigmentation.
Extracts of Dianella ensifolia contain 1-(2,4-dihydrophenyl)-3-(2,4-dimethoxy-3-methylphenyl) propane (DP), which was found to inhibit the free radical 1-1-diphenyl-2-picryl-hydrazyl (DPPH) with an EC50 value of 78 μm. DP was also found to inhibit UVC-induced lipid oxidation with an EC50 of about 30 μm. Next, researchers investigated the effects of this antioxidant on skin hyperpigmentation. The reduction of discoloration by different topical treatments has been assessed in human volunteers using an in vivo assay for the rate of fading of UVB-induced tan. Two pharmaceutical formulas containing 4 percent hydroquinone (HQ) were used as positive controls, and the ability of DP—a plant-derived amphoteric antioxidant—to increase performance of non-HQ cosmetic formulations was tested.