Planta Med 2011; 77 - PA14
DOI: 10.1055/s-0031-1282210

Isothermal Titration Calorimetry as a tool for selection of new natural astringents for cosmetic applications

F Rosini 1, SD Junior 2, MS Nakamura 2, C Montanari 1
  • 1Department of Chemistry and Molecular Physics, Institute of Chemistry of São Carlos, University of São Paulo, Brazil
  • 2Natura Cosmetics, São Paulo, Brazil

The use of astringents in the cosmetic industry is widespread as tonic lotions, cleansers, deodorants and antiperspirants. Aluminium chlorohydrate, among others aluminium salts, is highly used as an astringent. Recently, the use of aluminum in cosmetics raised the concern about its safety to humans. Although the regulatory agencies worldwide assure the safety of this raw material, this issue has led the search for substitutes of aluminium salts to serve consumer needs. In the deveolpment of new raw materials it is wise to evaluate a priori the in vitro efficacy to address the extremely complex functional systems of living organisms. Colorimetric titration methods for evaluating tannins based on precipitation of hide powder (1) are very laborious and not specific to tannins (2). The objective of this study was to apply the isothermal titration calorimetry (ITC) method, as described elsewhere by others (3,4,5), to evaluate the interaction of bovine gelatin with 8 commercially available natural and semi-synthetic tannin containing extracts. The bovine gelatin is an especially good source of proline binding sites found in human skin. The tannins belong to the hydrolysable and condensed types present in 5 different plant species. ITC is a reliable and fast technique to evaluate important parameters like enthalpy, entropy, stoichiometry and association binding constant in an unique experiment for further decision support. All raw materials had the efficacy compared to aluminium chlorohydrate. The developed methodology has provided an useful tool for astringency evaluation of tannins and will illuminate the road toward better cosmetics.

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