500 JOURNAL OF COSMETIC SCIENCE Fonnation of Lipid Emulsions and Clear Gels by Liquid Crystal Emulsification Toshiyuki Suzuki, Hidetaka Jwai Kao Corporation, Global R&D, 2-1-3 Bunka, Sumid.a-ku, Tokyo 131, Japan Recentlv developed emulsion technolo�es for the formation of fine emulsions, lipid emulsions and clear gels by liquid crvstal emulsification were reviewed. As a basic information o liquid crystal emulsification, the structures and characteristic behaviors of lyotropic liquid crystals were summarized. Fonnation of a liquid crystalline phase was often seen in emulsions and biologic.a I systems. The si gn ificance of liquid crystal fonnation during emulsification was analyzed by comparing the states and stabilities of emulsions prepared by different processes. Then uses of liquid crystals for fonnation of the characteristic emulsion and gels were also discussed. In liquid crystal emulsification, an oil phase is dispersed directly into the lamellar liquid­ crysta Hine phase composed of surfactant, glycerol and water to prepare a gel-like oil-in-liquid crystal emulsion. This is followed by dilution with the remaining water lo produce an emulsion. From the phase behavior during emulsification and analysis of the local motion of the liquid crystal membrane by fluorometry, it was confirmed that the interaction between surfactant and a polyol molecule such as glycerol promotes hydrogen bonding and enhances the strength of the lamellar liquid crystal membranes, which results in the formation of oil-in-liquid crystal emulsions. The interaction between the liquid crystal and oil was analyz.ed from the changes in molecular motion of the membrane at the oil-liquid crystal interface using the spin label technique of electron spin resonance (ESR). The fluidity of the liquid crystal membrane did not change when oil was added, and therefore oil-in-liquid crystal emulsions of various oils were prepared by the identical process. This lack of dependence of the liquid crystal membrane on oil results in the unique properties of liquid crystal emulsification, which can be used for oil of various polarity and different molecular corn,tituents. When a self-organizjng artificial stratum comeum lipid containing pseud�amide was used as a principal component of the oil, a multilamellar emulsion of concentric lamellar structure was fonned. The multilamellar emulsion supplement the physiological function of stratum comeum by the identical mechanism as natural intercellular lipid'i. High pressure treatment of the lipid emulsion produced a gel-like emulsion crystal, in which the homogeneous nanoemulsion droplets were arranged in a hexagonal array. Hydroxy Dimethoxybenzyl Malonate: A Novel Anti­ (Photo )aging Concept Thomas Rudolph, Philipp Biihle, Jorn Beck, Frank Pflocker, Karl-August Reiffen, and Herwig Buchholz Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany Ideally, anti-(photo)aging concepts should provide maximum efficacy, perfect stability and cosmetic (formulation) elegance. The need for high efficacy paired with excellent stability appeared contradictive but was resolved by designing complete redox systems rather than antioxidants alone. We here introduce a new class of cosmetic redox pairs, each comprising the initial antioxidant plus its oxidation product. The chemical properties of the oxidation product are the key to enabling the system to maintain or even increase its initial efficacy. A series of antioxidant tests were used to carefully characterize single redox pair components for comparison with traditional antioxidants such as vitamin C and E derivatives (DPPH, lipid and TEAC assays). Kinetic studies on the photobehavior of a selected redox pair were carried out in cosmetic emulsions with solar simulation and monitored by UV spectroscopy and high performance liquid chromatography. Hydroxy dimethoxybenzyl malonate (HDBM) is a pure transparent cosmetic oil. It shows excellent cosmetic stability coupled with extraordinary antioxidant properties. This controlled activity can be explained well by the presence of its oxidation product hydroxy dimethoxybenzylidene malonate (HDBMox), which provides ongoing antioxidant activity plus excellent UV A absorbing properties. The redox pair described here provides the advanced on-demand benefit of a non-UV-absorbing photoprotector that is converted into its UV-absorbing equivalent upon light exposure. Prebiotic Cosmetics: An Alternative to Antibacterial Product' Dirk Bockmuhl, Claudia Jassoy, Silke Nieveler, Regine Scholtyssek, Armin Wadle, and :Marianne Waldmann-Laue Henkel KGaA, 40191 Diisseldorf: Germany The concept of prebiotics is well known from food product'!, where several ingredients are used to stimulate the beneficial gut microflora. However, prebiotic substances can in principle be applied to balance almost any microbial community to achieve advantageous effects. Since many cosmetic products target skin bacteria as a cause for undesirable conditions like inflammation or body odor, prebiotic actives can help to cope with these problems in a very effective way. To ensure a focused and successful mode of action we demonstrated that it is essential to analyze the microflora and the interactions between different bacterial species carefully. These analyzes were made using a molecular method, fluorescence in situ hybridization (FISH), allowing a precise determination of a bacterial community without the drawbacks of classical culture methods. In a further step it was then possible to identify new actives tha1 inhibit harmful or unwanted bacterial species while protecting the beneficial flora. Using a quick and reliable in vitro screening method we found several plant extracts (e.g. Ginseng or Black currant) which inhibit the inflammation­ causing bacterium Propionibacterium acnes, but do not affec1 beneficial species like coagulase-negative staphylococci. In addition, it could also be demonstrated that a prebiotic product line for treatment of inflamed (or acne prone) skin showed the predicted effects on the microflora composition in a first in vivo trial, i.e. decrease of Propionibacterium acnes a1 a constant level of total bacteria. After three weeks, th� microtlora of 91 % of the volunteers had been rebalanced in this way. Furthermore, these formulations have been shown to exhibit excellent skin compatibility compared to an antibacterial product. Thus, prebiotic substances have thf potential to provide a gentle and sustainable alternative tc undirected antibacterial ingredients which can causf irritation, and frequently only show short time effects.

ABSTRACTS 501 Hydroxy Dimethoxybenzyl Malonate: A Novel Anti­ (Photo)aging Concept Thomas Rudolph, Philipp Biihle, Jorn Beck, Frank Pflilcker, Karl-August Reiffen, and Heiwig Buchholz Merck KGaA, Frankfurter Strasse 250, 64293 Darmstadt, Germany Ideally, anti-(photo)aging concepts should provide maximum efficacy, perfect stability and cosmetic (formulation) elegance. The need for high efficacy paired with excellent stability appeared contradictive but was resolved by designing complete redox systems rather than antioxidants alone. We here introduce a new class of cosmetic redox pairs, each comprising the initial antioxidant plus its oxidation product The chemical properties of the oxidation product are the key to enabling the system to maintain or even increase its initial efficacy. A series of antioxidant tests were used to 'carefully characterize single redox pair components for 'comparison with traditional antioxidants such as vitamin C and E derivatives (DPPH, lipid and TEAC assays). Kinetic :studies on the photobehavior of a selected redox pair were 'carried out in cosmetic emulsions with solar simulation and monitored by UV spectroscopy and high performance liquid 1 chromatography. Hydroxy dimethoxybenzyl malonate 1 (HDBM) is a pure transparent cosmetic oil. It shows excellent 'cosmetic stability coupled with extraordinary antioxidant properties. This controlled activity can be explained well by the presence of its oxidation product hydroxy 'dimethoxybenzylidene malonate (HDBMox), which provides 'ongoing antioxidant activity plus excellent UV A absorbing properties. The redox pair described here provides the ,advanced on-demand benefit of a non-UV-absorbing photoprotector that is converted into its UV-absorbing 'equivalent upon light exposure. 4-(l-Phenylethyl)l,3-Benzenediol: A New, Highly Efficient Lightening Agent Gabriele Vielhaber, Gerhard Schmaus, Karin Jacobs, Helge Franke, Sabine Lange, Martina Herrmann, Holger Joppe, and Oskar Koch Research Cosmetic lngredients, Symrise GmbH & C',o KG, Miihlenfeld1tr. 1, 37603 Holzminden, Gennany There is an increasing world-wide demand for skin lightening active ingredients. Many common lightening ingredient'! on the market are either unsafe or ineffective at low concentrations. We therefore screened a series of hydroxy­ stilbene derivatives for tyrosinase inhibitory activity. By chemical synthesis, the structures were optimized for efficacy and stability. The final candidate, 4-( 1-phenylethyl)l,3- benzenedioL was found to be stable and to inhibit mushroom tyrosinase 22 times more effectively than kojic acid. In an assay with B 16V melanoma cells, 4-( 1-pheny!ethyl) 1,3- benzenediol was the most potent inhibitor of melanin synthesis with an IC,0 of 2µM among the compounds investigated. The lightening effect of 4-( 1-phenylethyl) 1,3- benzenediol was not due to cytotoxicity as proved by an MTT assay on B16V cells. On pigmented 3D epidermis models, 0.1% of 4-(1-phenylethyl)l,3-benzenediol led to an almost complete suppression of melanin synthesis after 14 da ys of incubation. Finally, an in vivo test on Aiian subject proved that 4-( 1-phenylethyl) 1,3-benzenediol efficiently lightens human skin at 0.5% dosage. Optimal results are achieved when 4-( 1-phenylethyl) 1,3-ben?.enediol is applied in formulations with low oil content In summary, we have demonstrated that 4-(1-phenylethyl)l,3-bemenediol 1s a potent, stable and safe skin lightener.