Dr Jan Knight reports on a pilot study on quantifying antioxidant activity, key to the development of long lasting cosmetic formulations
Antioxidants play an important role in protective and repair mechanisms within the skin and their incorporation into cosmetics preparations has become very popular. However, just adding an ingredient with known antioxidant properties to a formulation does not necessarily confer antioxidant properties on the finished product. More is not necessarily better, especially as some antioxidants can actually become pro-oxidant under certain circumstances.[1] Quantifying antioxidant activity accurately in the ingredients and finished product is necessary in order to optimise formulations, define frequency of application and in addition, provide a quantitative method to confirm shelf life. However, the reproducibility of the methods used to measure this activity must be significantly greater than what a manufacturer might tolerate in normal deterioration over 6-12 months. If 5-10% deterioration over six months is acceptable, then the methods to measure activity must be highly reproducible with variations no more than 3%.