Technically Speaking: Solid Lipid Nanoparticles in Sunscreens and Other Topics

Skin and Skin Care
Carrageenan and carbonate diesters: Pola Chemical Industries discloses skin cleansing compositions containing carrageenan and carbonate diesters. The described invention relates to a skin emulsion composition, especially a keratotic plug-removing and skin-cleansing composition, containing 0.5–2.0% carrageenan and 0.1–50% of a carbonate diester such as dicapryl carbonate. The composition disclosed has a high viscosity with improved storage stability of the carbonate diester and may further contain 0.1–20% sodium chloride.

Heat-generating salts: Kosei Co. Ltd. discloses skin-warming massage compositions containing glycerin, glycerin-modified silicones and heat-generating salts. The skin-warming massage compositions consist of a first component containing glycerin and a glycerin-modified silicone and a second component containing a cosmetically applicable salt that generates heat by dissolving in water. The first and second compositions are mixed before application and either may further contain spherical powders. The massaging composition is reported to spread smoothly on the skin and exhibit excellent storage stability. Disclosed is an example formulation of a first composition containing 50% glycerin, polyglycerin-modified silicone, a fragrance, a preservative, a colorant and water; and a second composition containing calcium chloride, a colorant and a preservative.

Hydroxystilbene derivatives for tyrosinase inhibition: Vielhaber et al. report on 4-(1-phenylethyl)1,3-benzenediol, a highly efficient lightening agent. An increasing worldwide demand for lightening products has spurred the development of new skin lightening actives; however, many common lightening ingredients on the market are either unsafe or ineffective at low concentrations. The investigators in this study therefore screened a series of hydroxystilbene derivatives for tyrosinase inhibitory activity. By chemical synthesis, the structures were optimized for efficacy and stability. The final candidate, 4-(1-phenylethyl)1,3-benzenediol, was found to be stable and to inhibit mushroom tyrosinase 22 times more effectively than kojic acid.

In an assay with B16V melanoma cells, 4-(1-phenylethyl)1,3-benzenediol was the most potent inhibitor of melanin synthesis. The lightening effect of 4-(1-phenylethyl)1,3-benzenediol was not due to cytotoxicity. On pigmented 3-D epidermis models, 0.1% of 4-(1-phenylethyl)1,3-benzenediol led to an almost complete suppression of melanin synthesis after 14 days of incubation.

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