Water-soluble UV Filters and Other Topics

By: Charles Fox, Independent Consultant

Posted: January 30, 2009, from the February 2009 issue of Cosmetics & Toiletries.

Skin and Skin Care
Skin smoothing: Beiersdorf AG discloses a method for reducing the signs of skin aging, particularly for mitigating and preventing wrinkles and expression lines, by using a rotating or oscillating brush for the application of skin-smoothing active ingredients^.1 It also relates to methods for smoothing the skin and improving surface structure. Accordingly, a cosmetic preparation is applied either to the skin requiring treatment or to a brush and subsequently worked into the skin by means of rotating or oscillating the brush. The cosmetic preparation in both approaches comprises at least one skin-smoothing active ingredient, such as coenzyme Q10. A skin-smoothing composition is shown in Formula 1.

Skin cleansing: Amorepacific Corp. discloses skin-cleansing compositions containing microcapsules including stabilized enzymes.² These microcapsules have a central core composed of white sugar or microcrystalline cellulose. Surrounding the core is a layer of stabilized enzymes, and surrounding this layer are seven coating layers composed successively of shellac, polymer, wax, cationic surfactant, polymer, anionic surfactant and polymer, from innermost to outermost layer. The microcapsules with stabilized enzymes in the enzyme layer have a triple-layer structure: an enzyme core is surrounded by a coating layer of hydrophobic macromolecular (> 1000 g/mol) polyol, and an outer layer of macromolecular wall material. The enzymes are selected from more than one of: hydrolase of lipase, amylase, pepsin, trypsin, urease, asparaginase and papain. The macromolecular polyol is selected from more than one of: polyethylene glycol, polypropylene glycol, and their copolymers. The macromolecular wall material is selected from more than one of numerous polymers made from various acids, esters, styrene, methacrylates and other monomers cited in the patent.

Even in a skin-cleansing composition having a high concentration (> 15%) surfactant system, the enzymes contained in these microcapsules are not degraded and maintain the enzyme activity enabling excellent skin cleansing.

Preservability: Kuraray Co., Ltd., and Pola Chemical Industries Inc. disclose skin preparations containing phospholipids and 4-alkylresorcinols with good transdermal absorption and storage stability.³ The 4-alkylresorcinols and/or their salts inhibit a decrease in preservability due to the phospholipids. The preparations may also contain antimicrobial polyols, N-acyl amino acids and/or phenoxyethanol as optional ingredients. Thus, hydrogenated soya lecithin liposomes were mixed with water, ultrasonicated, mixed with 1,3-butanediol, and 4-butylresorcinol, and emulsified upon gradual addition to a mixture of glyceryl triisooctanoate, sorbitan sesquistearate, and polyoxy ethylene sorbitan monostearate to give an emulsion containing liposomes dispersed in the inner aqueous phase. The emulsion showed good antifungal activity against Aspergillus niger.

Free radical scavenger: Faming Zhuanli Shenqing Gongkai Shuomingshu discloses a free radical scavenger used in cosmetics for resisting aging, preventing sunburn and repairing skin after sunburn.⁴ The free radical scavenger is prepared from Sophora japonica flower bud, Canarium album fruit and Chaenomeles speciosa fruit at 5.6–51.2, 2.9–38.3 and 10.7–43.1 parts by weight, respectively. Optional ingredients include Eugenia caryophyllata, Scutellaria baicalensis and Sophora japonica flower at 0.9–33.3, 1.9–17.5 and 3.2–41.4 parts by weight, respectively. These botanicals are extracted with a solvent such as methanol, 70% ethanol or absolute ethanol. The mixture is effective against such free radicals as 1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, superoxide anion radicals, hydroxyl radicals, or mixtures thereof.