Cutaneous radical scavenging effects of orally administered antioxidants measured by electron paramagnetic resonance spectroscopy

SummaryBackground and aimsThe intake of nutritional supplements such as vitamins and antioxidants is popular but still controversially discussed. For effective prevention in premature skin ageing and skin cancer, cutaneous radical scavenging activity should increase after the intake of antioxidants. So far, a non-invasive evaluation procedure for the radical scavenging capacity was not at our disposal. Therefore, electron paramagnetic resonance (EPR) spectroscopy was utilized in vivo to determine the radical scavenging capacity of the skin.Methods33 volunteers were investigated, before and after the intake of placebo, vitamin C or a chokeberry peel extract (Aronia) for 28 days. Both experimental products were provided with the same radical scavenging activity. The amount of product corresponded to 125 mg (0.29 mmol) calcium ascorbate per day or 800 mg Aronia combined with 40 mg calcium ascorbate.ResultsOral supplementation with vitamin C and Aronia significantly increase the radical scavenging capacity of the skin by 22% and 23%, respectively using the test radical TEMPO. No uptake was observed within the placebo group.ConclusionIn vivo EPR technique offers a medical evaluation of orally consumed antioxidants regarding the radical scavenging capacity and could demonstrate that a natural product including phenolic compounds has the same effect as vitamin C in the skin if TEMPO is used as a test radical.