C¾CLODEXTRINS 189 cyclodextrin complexes are used in the following products: Eucerin Vital Retinol © (Beiersdort), Nutrients & Anti-aging Agents © (Efal), and Dexol A © (Collaborative Labo- ratories). Cyclodextrins are also used to increase the solubility of substances secreted by the skin, and thus they are used in products for skin cleaning. They are able to complex and to dissolve skin fat. The formed fat complex with cyclodextrins can be easily removed from the skin. Therefore cyclodextrins, together with other ingredients, are in a product named Gesichtstonic © (Annemarie B6rlind). ELIMINATION OF UNDESIRED ODORS Dihydroxyacetone is used as tanning agent. It is not stable in aqueous solution. More important is the unpleasant odor of dihydroxyacetone, which is difficult to mask by perfumes. This odor vanishes using the cyclodextrin complex. The slow release of di- hydroxyacetone from the complex results in a more uniform tanning of the skin. This cyclodextrin complex is used in Ultrasun Selftan © (Ultrasun) and in Self-Action Super Tan For Face © (Est6e Lauder). Glutathione shows various physiological activities. For example, it inhibits melanin pigment formation. Thus it may be used for skin whitening and skin-improving effects. Unfortunately, glutathione generates an offensive odor upon use in cosmetic formula- tions. The glutathione complex with cyclodextrin is free of the odor of glutathione and has the same effect on the skin as glutathione (32). Mercapto compounds are often used in waving lotions. Due to the presence of mercapto derivatives, an extremely unpleasant odor is generated during application. This odor is often masked in part by the addition of perfumes to the lotion. A more efficient possibility is the use of cyclodextrins. Due to complex formation with the mercapto compounds, the unpleasant odor is eliminated (33). Chamomile extracts or oil have an antiphlogistic, bacteriostatic, and wound-healing effect. These formulations often have an intense and unpleasant odor. This odor is reduced by complexation with cyclodextrins. The antifiammatory activity of chamomile extracts remains unaffected (34). Deodorants are used to control malodors formed by microbial degradation of sweat. Cyclodextrins and mixtures of cyclodextrins can be used in deodorant sticks. The cy- clodextrins are able to complex perspiration malodors (35). IMPROVEMENT OF HANDLING Liquid or oily substances as powders. The oily o•-tocopherol acts as an antioxidant. It is used in many personal care products to protect the surface of the stratum corneum from damage caused by free radicals. As a cyclodextrin complex it is not soluble in water or oil. It should be used as a powder or suspended in lotions and creams (Lipo Chemicals Inc.). The formation of complexes with cyclodextrins serves to enhance the stability of tocopherol (36,37). Octyl methoxycinnamate is used as an oil-soluble sunscreen. As a cyclodextrin complex it is also not soluble in water or oil. The complex can be used in formulations as a powder

190 JOURNAL OF COSMETIC SCIENCE or suspended in appropriate cream and lotion vehicles. In these formulations a slow release of octyl methoxycinnamate from the complex takes place, resulting in a long- lasting protection of the skin (Lipo Chemicals Inc.). Stability of emulsions. In a simple three-component system of paraffin oil, water, and [3-cyclodextrin, stable emulsions are formed. The formed emulsions are stable under various storage conditions. However, the origin of this stabilization effect can not be given at present (38). The apparent viscosity of these emulsions strongly depends on the cyclodextrin concentration. The stabilization effect of [3-cyclodextrin on emulsions formed from triglyceride and water has also been reported (39). CONCLUSION Cyclodextrins are already used in cosmetic products. They offer many advantages. For example, the discussed effects of the stabilization of substances, reducing their vapor pressure, and increasing their solubility cannot be easily achieved with other formulation techniques. Due to further decreases in their prices, more applications will become possible in the near future. The use of textiles with permanently fixed cyclodextrins offers new applications for cosmetic formulations (14). These textiles may act as depots for cosmetic compounds. They will be released from the cyclodextrins only in contact with the skin. ACKNOWLEDGMENT Financial support within the scope of the project "Textile" from the Ministerium ftir Schule, Wissenschaft und Forschung of Nordrhein-Westfalen is gratefully acknowl- edged. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) A. Villiers, Sur la transformation de la fdcule en dextrine par le ferment butyrique, Cornpt. Rend. Acad. Sd. Paris, 112, 435--437 (189l). F. Schardinger, Ober thermophile Bakterien aus verschiedenen Speisen und Milch, sowie tiber einige Umsetzungsprodukte derselben in kohlehydrathaltigen Niihrl/3sungen, darunter krystallisierte Poly- saccharide (Dextrine) aus Stiirke, Z, Untermch. Nahrungsm. Genussm., 6, 865-880 (1903). K. Freudenberg, G. Blomqvist, and L. Ewald, Hydrolyse und Acetolyse der Stiirke und der Schard- inger-Dextrine, Chem. Ber., 69, 1258-1266 (1936). K. Freudenberg and F. Cramer, Die Konstitution der Schardinger-Dextrine ix, [3 and •, Z. Naturfor- schg., B3, 464 (1948). W. Borchert, R/3ntgenographische Untersuchungen an Schardinger-Dextrinen, Z. Naturforschg., B3, 464-465 (1948). .. F. Cramer, Uber EinschluBverbindungen, I. Mitteil: Additionsverbindungen der Cycloamylosen, Chem. Ber. 84, 851-854 (1951). W. Saenger, Cyclodextrin inclusion compounds in science and industry, Angew. Chem. Int. Ed., 19, 334-352 (1980). J. Szejtli (Ed.), Proceedings of the First International Symposium on Cyclodextrins (D. Reidel, Dordrecht, 1982). J. Szejtli, Cyclodextrins and Their Inclusion Complexes (Akademiai Kiado, Budapest, 1982). K.-H. Fr/3mming and J. Szejtli, Cyclodextrins in Pharmacy (Kluwer, Dordrecht, 1994).