Prevention of oxidative damage that contributes to the loss of bioenergetic capacity in ageing skin.

Skin ageing is a complex biological process related to a decline in physiological and biochemical performance. A decline in the mitochondrial energy production is a feature of ageing at the cellular level. This is partially attributed to excessive production of reactive oxygen species such as superoxide and hydrogen peroxide in aged individuals. We have investigated the effect of (glyc)oxidative stress on two biochemical targets relevant for the energy metabolism of the skin. First, we showed an age dependent decline in the activity of the hydrogen peroxide detoxifying antioxidant catalase in stratum corneum on a chronically sun-exposed site. Furthermore catalase was sensitive to peroxynitrite-induced in vitro inactivation. Catalase mimetics as well as peroxynitrite scavengers are proposed to maintain hydrogen peroxide detoxification pathways. The second target was creatine kinase, an enzyme that controls the creatine-creatine phosphate shuttle. Creatine kinase lost activity after in vitro glycation by methylglyoxal. This activity loss could be prevented by antiglycation actives. These data suggest that biomolecules involved in energy homeostasis become damaged by different sources of stress. Actives specifically selected for optimal protection against these stress situations will decrease skin vulnerability and prevent the premature loss of skin function.