ABSTRACT
In nature, there are a plethora of different antioxidants in plants and other biological species. Extracts from these species are often used in cosmetic preparations. To determine the antioxidant potential of such extracts and other antioxidants in cosmetics, foods, and biological systems, antioxidant assays are commonly employed to determine the reaction efficiency between a selected antioxidant and a chemical probe. As a result of such high demand, a number of assays to measure antioxidant efficacy have become available in the last twenty years. These assays differ from the lipid peroxidation assays discussed in Chapter 5 in so far as antioxidant assays measure reaction kinetics and do not investigate degradation products of lipids. In general, the assays are easy to employ and provide useful information about antioxidant systems, especially when comparing a series of antioxidants. There are, of course, criticisms of the assays. For example, it can be argued that the reaction kinetics observed with an assay probe will be intrinsically different than the actual in vivo situation. Moreover, molecular mobility will not be the same in vivo as in a solution containing only a few reagents. A similar argument could be proposed for complex formulations, such as those found in cosmetics. Regardless, these tools (the assays) provide an insight concerning the feasibility of antioxidant species with prospective use in skin care applications.
