MedicalResearch.com interview with: J. Kühnl, D. Roggenkamp, G. Neufang. Research & Development, Beiersdorf AG, Hamburg MedicalResearch:What is the background for this study? What are the main findings? Response: The skin is constantly challenged by environmental stressors that induce inflammatory processes, resulting in skin damage and –in the long term- consequently aging processes. UV-irradiation is an important exogeneous stressor. Even the best filter systems do not completely abolish the impact of UV radiation. For example, after application of a SPF50+ sun lotion, about 2% of UV-rays still reach the skin. However, the skin developed strategies to cope with exogenous stressors: Intracellular thiols quench harmful UV-derived free radicals and a multitude of detoxifying enzymes convert noxious compounds and metabolites into harmless species. We strived to specifically stimulate these cytoprotective cellular systems in order to tip the balance in favor of more robust skin cells. Previous studies showed that the root extract of the plant Glycyrrhiza inflata (Chinese Licorice) exhibits anti-inflammatory and anti-microbial effects. The major phenolic constituent of the licorice extract is Licochalcone A (LicA) and this compound is largely responsible for the beneficial effects. This was explained by LicA´s inhibitory effect on the pro-inflammatory transcription factor NFkB and its antioxidant properties. However, in this study, we could add another facet of LicA´s efficacy: by activating the transcription factor Nrf2, LicA stimulates the expression of cytoprotective enzymes such as heme oxygenase I and the key enzyme of glutathione synthesis, resulting in increased intracellular thiols concentrations. Consequently, when pre-incubated with LicA, isolated human skin cells were more robust against solar simulated light-induced cellular damage, indicated by a significantly decrease in the generation of free radicals in vitro. In a translational approach, we conducted a study with healthy volunteers demonstrating that the application of a lotion containing LicA-rich root extract on the inner forearms for two weeks protected the skin from UV-provoked oxidative stress. Thus the cellular effects of licorice are able to provide a protective shield from sun exposure, supporting and going beyond the action of sunscreens regarding sun protection. (more…)