The determination of the radical power - an in vitro test for the evaluation of cosmetic products.

OBJECTIVE Cosmetic formulations are influenced by environmental impacts and ageing, resulting in rancidity and change of colour and structure. These changes are caused by free radicals (FRs). The sensitivity of cosmetics generating FRs is a metric for its quality and should be determined. METHODS Electron spin resonance spectroscopy in combination with UV irradiation tested cosmetics such as creams, milks, lotions and fragrances. The probes were directly measured without expensive preparation. RESULTS Nine formulations are tested for its radical generation and ranked corresponding to the radical power. The transformation of the FR properties of three formulations to skin is measured by the radical skin status factor (RSF) method. It shows that the higher the radical power (RP) is, the lower the radical status RSF of skin will be. CONCLUSION The knowledge of the sensitivity of cosmetics to generate FRs is necessary for its stabilization and prevention of potential damages to skin. It is a new way in development of cosmetics which has to be considered.