Free radicals are involved in natural physiological processes in the skin but also are responsible for oxidative stress resulting in damage to cellular components—ultimately leading to premature aging and diseases. Oxidative stress can occur when the number of free radicals surpasses the capacity of the body’s natural defense mechanisms. This can be due to environmental factors such as exposure to UV radiation and pollutants.
Several in vitro tests exist1,2 to assess the free radical scavenging ability of ingredients in cosmetics and personal care, and there are even in vivo tests available to assess the efficacy of products to prevent lipid oxidation. This paper discusses the application of two-photon fluorescence microscopy to determine the effects of cosmetic formulations on the amount of reactive oxygen species (ROS) formed in skin models.